tag:blogger.com,1999:blog-112829592024-03-08T03:33:15.711-05:00AA6E Station LogNotes from an Amateur Radio operator.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.comBlogger247125tag:blogger.com,1999:blog-11282959.post-70531938828255925772023-04-24T10:28:00.000-04:002023-04-24T10:28:42.823-04:00Plus ça change... Time to check in once more.<p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://unicode.org/emoji/charts/full-emoji-list.html" rel="nofollow" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;" target="_blank"><img data-original-height="324" data-original-width="535" height="194" src="https://blogger.googleusercontent.com/img/a/AVvXsEhvRt5HKBj4Q8_lJQlSpoIkRa4Mt4dlxQWYqsoSbeebFZ3d_c0hLM-uPfhxJ4GJGfn83i6MHjAerI9CW5dPdVb8qH3w3kOggJSDk1nqDj5km-ZM8Kap_1JJRLIG1MTx3MVEzC943bv6Q8YVG-gYHRzfyuu8BuyC7gPcbHPhsM2EPaKZzhk9dsM=w320-h194" width="320" /></a></div>This blog needs some attention! It has been over a year now. The Blogger service is changing, and the world of social media is evolving drastically. I've just cancelled my Twitter account, which draws a close to that small chapter in my life. Elon is now free to drive things into the ground without my help.<p></p><p>I've dumped Instagram and Facebook, also. The idea is to reclaim as much of my time as I can, free of the morbid stuff on the Internet. That should allow me to concentrate on more important things. That, or I can just enjoy a bit of peace as I enter deeper into codger-hood.</p><p>This old-fashioned blog is an interesting case. I can write what needs to be written, at whatever length. Comments are welcome. It should remain mainly technical with an amateur radio focus, but there will be tangents.</p><p>Let's see how it evolves.</p>Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-73825095564880326062021-12-14T16:37:00.010-05:002021-12-24T16:54:15.511-05:00A Death Foretold (Toshiba)<p>Eleven years is nearly an eternity for computing hardware. In my IT glory days, we said that a 3 year old PC was effectively at its end of life. We tried to budget for a 3-year replacement cycle, but it often stretched to 4 years. The technology zoomed ahead so fast that an older computer would barely run the latest operating system and fancier software applications.</p><p>That's easy to say when we're talking about other people's money, but for myself, I try to stretch my investments when I can.</p><p></p><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgqqVtSZWSNv3uV8gLRLDmlsyD7WI8gmSxZ9JthS67hsQrglHy-AB4DOBPgEfbTHvuFXHY-N-ScMiE85BSfOAEEIpebpnXA6C057mHouET3dh4_YDeWmNrrpZyXJQvKnhU9sbymvdTN4PoMKP_2XX4eg1T_cQ78dwbTuEQ3UhlW2mTKKIg7toc=s465" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="349" data-original-width="465" height="240" src="https://blogger.googleusercontent.com/img/a/AVvXsEgqqVtSZWSNv3uV8gLRLDmlsyD7WI8gmSxZ9JthS67hsQrglHy-AB4DOBPgEfbTHvuFXHY-N-ScMiE85BSfOAEEIpebpnXA6C057mHouET3dh4_YDeWmNrrpZyXJQvKnhU9sbymvdTN4PoMKP_2XX4eg1T_cQ78dwbTuEQ3UhlW2mTKKIg7toc=s320" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Toshiba L645D</span><br /></td></tr></tbody></table>The last laptop computer I acquired was this <a href="https://content.abt.com/documents/29646/L645DS4058_specs.pdf" target="_blank">Toshiba L645D</a>. In 2010, it was already an economy model selling at a hair under $500. With its "triple core" AMD processor, you got Windows 7. Upgraded to dual boot Ubuntu Linux, it served for presentations and other uses for a good 10 years.<p></p><p>Not forever, though. Recently I brought it out for some reason and found that its battery would not take a charge. (I was on my second battery.) OK, new batteries are available for about $25. I got one, and verified that it would charge up normally, according to the LED indicators. So I pushed the power button, but apart from a few LED flashes nothing more happened. No display, no boot.</p><p>OK, there's another battery to check. The "CMOS" battery is a 3-volt lithium cell, like the one that probably lives in your PC. You have to unbutton your machine and dig for it. I dug for mine, but it popped up and out and into the internals of the laptop. Oops. That means I have to disassemble the machine -- not a simple task. Fortunately, there are good instructions at <a href="http://ifixit.com">ifixit.com</a> for just this system.</p><p>I got it apart and found the battery OK, and I was set to put in a new one. But the battery holder was a flimsy plastic item that I had broken when I removed the old battery. Yikes! Amazon had a replacement that seemed compatible, so I ordered it and waited a couple of days. (10 of them for ~$7.) Removing the old holder and putting in the new one required some semi-precision soldering, but it seemed to go alright.</p><p>Reintegrating the laptop parts (a 20+ step process) went not quite as smoothly as the disassembly, but well enough. I only had one small screw left over.</p><p>Alas, the Toshiba did not come to life! I am now reflecting on why I would put so much time into a system that at best would still be obsolete.</p><p>At least I do have a new battery pack and an 11 year old 320 GB SATA hard drive for the junk box.<br /></p>Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-91471228499785486142019-11-17T22:19:00.000-05:002019-11-18T00:37:08.192-05:00On the air with new antenna!<div class="separator" style="clear: both; text-align: center;">
<a href="https://aa6e.net/nw/images/whitfield_ants.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="381" data-original-width="800" height="304" src="https://aa6e.net/nw/images/whitfield_ants.png" width="640" /></a></div>
<br />
You can see our new 86 ft inverted-V-non-resonant dipole on top the "Whitfield" building at <a href="https://evergreen-woods.com/" target="_blank">Evergreen Woods</a>, our new QTH. Fed by 400 ohm ladderline to our 2nd floor apartment at the right, it was a long slog to get installed. Lots of help from friendly facilities staff, however. A 4:1 balun connects our ladderline to either the Flex-6500 directly or through a Heathkit SA-2060A Antenna Tuner.<br />
<br />
First test shows it's a good 40 M antenna, easily matched with the built-in ATU of the Flex-6500. Other bands can be a challenge, but the SA-2060A will tune this system over 160 - 6 M -- at least if you're willing to crank those knobs!<br />
<br />
My first on-air test was on 80 M with the SA-2060A. This is a difficult match, because the 86 ft dipole is close to a quarter-wave at 3.6 MHz. Does it work? I set it up with WSPR at 5 W transmit power to see what came back. Partial results of the first few minutes:<br />
<br />
<table cellpadding="2" cellspacing="0" style="width: 468px;">
<colgroup><col width="110"></col>
<col width="52"></col>
<col width="71"></col>
<col width="27"></col>
<col width="62"></col>
<col width="56"></col>
<col width="32"></col>
<col width="26"></col>
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<tr>
<th style="border: none; padding: 0in;" width="110"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">Timestamp</span></span></th>
<th style="border: none; padding: 0in;" width="52"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">Call</span></span></th>
<th style="border: none; padding: 0in;" width="71"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">MHz</span></span></th>
<th style="border: none; padding: 0in;" width="27"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">SNR</span></span></th>
<th style="border: none; padding: 0in;" width="62"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">Reporter</span></span></th>
<th style="border: none; padding: 0in;" width="56"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">RGrid</span></span></th>
<th style="border: none; padding: 0in;" width="32"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">km</span></span></th>
<th style="border: none; padding: 0in;" width="26"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">az</span></span></th>
</tr>
<tr>
<td style="border: none; padding: 0in;" width="110"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2019-11-18
02:36</span></span></td>
<td style="border: none; padding: 0in;" width="52"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">AA6E</span></span></td>
<td style="border: none; padding: 0in;" width="71"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3.570022</span></span></td>
<td style="border: none; padding: 0in;" width="27"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">-24</span></span></td>
<td style="border: none; padding: 0in;" width="62"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">HB9TMC</span></span></td>
<td style="border: none; padding: 0in;" width="56"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">JN46lj</span></span></td>
<td style="border: none; padding: 0in;" width="32"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">6279</span></span></td>
<td style="border: none; padding: 0in;" width="26"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">55</span></span></td>
</tr>
<tr>
<td style="border: none; padding: 0in;" width="110"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2019-11-18
02:38</span></span></td>
<td style="border: none; padding: 0in;" width="52"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">AA6E</span></span></td>
<td style="border: none; padding: 0in;" width="71"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3.570021</span></span></td>
<td style="border: none; padding: 0in;" width="27"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">-24</span></span></td>
<td style="border: none; padding: 0in;" width="62"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">PA0O</span></span></td>
<td style="border: none; padding: 0in;" width="56"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">JO33hg</span></span></td>
<td style="border: none; padding: 0in;" width="32"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">5815</span></span></td>
<td style="border: none; padding: 0in;" width="26"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">48</span></span></td>
</tr>
<tr>
<td style="border: none; padding: 0in;" width="110"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2019-11-18
02:36</span></span></td>
<td style="border: none; padding: 0in;" width="52"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">AA6E</span></span></td>
<td style="border: none; padding: 0in;" width="71"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3.570022</span></span></td>
<td style="border: none; padding: 0in;" width="27"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">-24</span></span></td>
<td style="border: none; padding: 0in;" width="62"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">TF1VHF</span></span></td>
<td style="border: none; padding: 0in;" width="56"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">HP84wl</span></span></td>
<td style="border: none; padding: 0in;" width="32"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">4091</span></span></td>
<td style="border: none; padding: 0in;" width="26"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">34</span></span></td>
</tr>
<tr>
<td style="border: none; padding: 0in;" width="110"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2019-11-18
02:34</span></span></td>
<td style="border: none; padding: 0in;" width="52"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">AA6E</span></span></td>
<td style="border: none; padding: 0in;" width="71"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3.570025</span></span></td>
<td style="border: none; padding: 0in;" width="27"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">-27</span></span></td>
<td style="border: none; padding: 0in;" width="62"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">KA7OEI-1</span></span></td>
<td style="border: none; padding: 0in;" width="56"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">DN31uo</span></span></td>
<td style="border: none; padding: 0in;" width="32"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3263</span></span></td>
<td style="border: none; padding: 0in;" width="26"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">284</span></span></td>
</tr>
<tr>
<td style="border: none; padding: 0in;" width="110"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2019-11-18
02:34</span></span></td>
<td style="border: none; padding: 0in;" width="52"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">AA6E</span></span></td>
<td style="border: none; padding: 0in;" width="71"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3.570023</span></span></td>
<td style="border: none; padding: 0in;" width="27"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">-18</span></span></td>
<td style="border: none; padding: 0in;" width="62"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">VE6JY</span></span></td>
<td style="border: none; padding: 0in;" width="56"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">DO33or</span></span></td>
<td style="border: none; padding: 0in;" width="32"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3250</span></span></td>
<td style="border: none; padding: 0in;" width="26"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">309</span></span></td>
</tr>
<tr>
<td style="border: none; padding: 0in;" width="110"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2019-11-18
02:38</span></span></td>
<td style="border: none; padding: 0in;" width="52"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">AA6E</span></span></td>
<td style="border: none; padding: 0in;" width="71"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3.570022</span></span></td>
<td style="border: none; padding: 0in;" width="27"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">-27</span></span></td>
<td style="border: none; padding: 0in;" width="62"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">KX3DX</span></span></td>
<td style="border: none; padding: 0in;" width="56"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">DM79</span></span></td>
<td style="border: none; padding: 0in;" width="32"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2723</span></span></td>
<td style="border: none; padding: 0in;" width="26"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">276</span></span></td>
</tr>
<tr>
<td style="border: none; padding: 0in;" width="110"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2019-11-18
02:34</span></span></td>
<td style="border: none; padding: 0in;" width="52"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">AA6E</span></span></td>
<td style="border: none; padding: 0in;" width="71"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3.570022</span></span></td>
<td style="border: none; padding: 0in;" width="27"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">-25</span></span></td>
<td style="border: none; padding: 0in;" width="62"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">N6GN/K</span></span></td>
<td style="border: none; padding: 0in;" width="56"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">DN70ll</span></span></td>
<td style="border: none; padding: 0in;" width="32"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2697</span></span></td>
<td style="border: none; padding: 0in;" width="26"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">279</span></span></td>
</tr>
<tr>
<td style="border: none; padding: 0in;" width="110"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2019-11-18
02:34</span></span></td>
<td style="border: none; padding: 0in;" width="52"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">AA6E</span></span></td>
<td style="border: none; padding: 0in;" width="71"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3.570022</span></span></td>
<td style="border: none; padding: 0in;" width="27"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">-26</span></span></td>
<td style="border: none; padding: 0in;" width="62"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">N5SNT</span></span></td>
<td style="border: none; padding: 0in;" width="56"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">EL09wq</span></span></td>
<td style="border: none; padding: 0in;" width="32"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2618</span></span></td>
<td style="border: none; padding: 0in;" width="26"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">249</span></span></td>
</tr>
<tr>
<td style="border: none; padding: 0in;" width="110"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2019-11-18
02:38</span></span></td>
<td style="border: none; padding: 0in;" width="52"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">AA6E</span></span></td>
<td style="border: none; padding: 0in;" width="71"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">3.570018</span></span></td>
<td style="border: none; padding: 0in;" width="27"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">-25</span></span></td>
<td style="border: none; padding: 0in;" width="62"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">KI5WA</span></span></td>
<td style="border: none; padding: 0in;" width="56"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">EM11jk</span></span></td>
<td style="border: none; padding: 0in;" width="32"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">2435</span></span></td>
<td style="border: none; padding: 0in;" width="26"><span style="font-family: "liberation sans" , sans-serif;"><span style="font-size: x-small;">251</span></span></td>
</tr>
</tbody></table>
<br />
So I think we pass. Best DX is HB9TMC in Switzerland, 2279 km = 3901 miles, with a Kp index of zero suggesting OK propagation..<br />
<br />
I had been worried about interference from our building HVAC and other systems. It's there, but so far it's no show-stopper. My first tests, inside the apartment, were a total disaster, but being 20-25 feet above the roof gets rid of most of it.<br />
<br />Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-77033379561728199742019-08-15T16:34:00.000-04:002019-08-15T16:34:55.468-04:00Casing the Environment<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-HJHdEqNWs5Q/XVW1TDnHBCI/AAAAAAAAsow/ypSVVIvYh0cj8g_tA8-sDUWUiqNPYOU_gCLcBGAs/s1600/Annotation%2B2019-08-15%2B150825_delta106k.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="836" data-original-width="1362" height="245" src="https://1.bp.blogspot.com/-HJHdEqNWs5Q/XVW1TDnHBCI/AAAAAAAAsow/ypSVVIvYh0cj8g_tA8-sDUWUiqNPYOU_gCLcBGAs/s400/Annotation%2B2019-08-15%2B150825_delta106k.png" width="400" /></a></div>
<br />
We have completed our move to Evergreen Woods, at least to the point of unpacking many of our boxes of "stuff". Time to check out the Electromagnetic Environment. <br />
<br />
It's not all good or all bad. The fact is that we're inside a fairly large complex of 249 apartments and commons buildings. We are in a rural/suburban setting, but the buildings have complex systems for HVAC, data networks, and power distribution. So we expect a somewhat challenging RFI situation for HF. You see one example above. All the peaks (separation ~106 kHz) seem to come from one source that probably gets here via the AC power line.<br />
<br />
I am using a Flex 6500 SDR as an RFI receiver with an EMCO 6502 active loop antenna. The antenna sits at my new second-floor operating position, not far from some metal objects that probably affect the measurements. The proposed antenna site is on the roof above the third floor, which is probably (hopefully) a somewhat better location!<br />
<br />
Zooming in to get some finer detail, we see three of these peaks in the 40 M band:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-JjiHWsSpyy8/XVW8w8U3ZjI/AAAAAAAAso8/0Y_ty-dwnugMSy8jeKgQs6ngPwZjRtbggCLcBGAs/s1600/Annotation%2B2019-08-15%2B161123.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="836" data-original-width="1363" height="245" src="https://1.bp.blogspot.com/-JjiHWsSpyy8/XVW8w8U3ZjI/AAAAAAAAso8/0Y_ty-dwnugMSy8jeKgQs6ngPwZjRtbggCLcBGAs/s400/Annotation%2B2019-08-15%2B161123.png" width="400" /></a></div>
<br />
A working hypothesis is that these may come from the building elevator system, with the glitches occurring during elevator motion.<br />
<br />
This 106 kHz frequency comb is not quite fatal for ham radio, because in most cases you can choose an operating frequency away from the RFI.<br />
<br />
There seem to be several sorts of RFI that become visible at various operating frequencies and various times of day. Some of them are quite broad (no narrow spectral peaks), and some are impulsive, like ignition interference or PLC-type digital signaling. The Flex 6500 has several noise blanking options that are at least partially effective.<br />
<br />
The antenna is probably going to be placed above the flat roof shown below:<br />
<br />
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<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-t5A0lZFd6Bo/XVW-0LVpF6I/AAAAAAAAspM/5f1F0cxWmKAYUZgKQuBWRAHuYgGiUP18ACLcBGAs/s1600/20190815_141124.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="763" data-original-width="1600" height="152" src="https://1.bp.blogspot.com/-t5A0lZFd6Bo/XVW-0LVpF6I/AAAAAAAAspM/5f1F0cxWmKAYUZgKQuBWRAHuYgGiUP18ACLcBGAs/s320/20190815_141124.jpg" width="320" /></a></div>
<br />
A diagonal run of about 100 ft looks possible, using 20 ft masts.<br />
<br />
Stay tuned for further developments!Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-54433014098286081052019-07-03T08:35:00.001-04:002019-07-03T08:35:46.968-04:00Migrating from Branford to North Branford CTAA6E moving on, see my web site: <a href="https://aa6e.net/nw/index.php/13-senior/25-aa6e-in-transition">https://aa6e.net/nw/index.php/13-senior/25-aa6e-in-transition</a>. The big shack picture is fading into history.<br />
<br />
We are thinking about quality instead of quantity here, as far as the ham activity goes.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-73310302983605951262019-06-15T09:39:00.002-04:002019-06-15T10:01:36.465-04:00Beginning of the End for FB<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-n6zd0UYsy7I/XQTsMW5YAGI/AAAAAAAAsWI/0nFoxDVbYtMFjqYn1js_OVgGzBY1KLfkgCLcBGAs/s1600/fbshot.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="38" data-original-width="144" src="https://1.bp.blogspot.com/-n6zd0UYsy7I/XQTsMW5YAGI/AAAAAAAAsWI/0nFoxDVbYtMFjqYn1js_OVgGzBY1KLfkgCLcBGAs/s1600/fbshot.png" /></a></div>
<br />
I killed off Google+ last year and started a little tradition. Today, I've killed off Facebook. At least, I'm deleting my personal account at FB.<br />
<br />
Why would I do that? Glad you asked!<br />
<br />
<ul>
<li>Facebook has a near monopoly position in social media. Benefiting from the "network effect" ("value" increases as the square of the number of users increases), FB has triumphed over all its competitors in the medium-long-form sharing segment.</li>
<li>Monopolies are generally bad. Anti-trust law evolves much more slowly than technology.</li>
<li>Facebook governance is effectively in the hands of one individual, who shows little appreciation for the public interest or the social impact of his company.</li>
<li>As a "free" service, users are persuaded to share way too much data with the service, often thinking it's just a matter of keeping up with friends or touting our lifestyles to the world.</li>
<li>Facebook makes lots of money by packaging and reselling our data to commercial or political interests.</li>
<li>For many users, Facebook is addictive.</li>
<li>The Facebook model especially encourages evil forces (read Russia or US ultrapartisans) to influence our political system, spreading rumors and all kinds of divisive false information.</li>
<li>Facebook has very little "quality control". There are weak attempts to suppress pornography, political abuse, and illegal conduct, but these are not very effective. For FB, quality control means reduced profits.</li>
<li>Apart from the shady business model, Facebook has a serious "signal to noise" problem. Over time, your friends (and friends of friends) can easily overwhelm your news feed with irrelevant and distracting (to you) material. As a reader, you have little control over what you see in your news feed.</li>
<li>The selection algorithms are obscure to users. They are meant to keep you engaged and clicking, but not to be useful. It can be really hard to return to a particular item you remember seeing a few hours ago.</li>
</ul>
None of these points are particularly original, I know. But you did ask!<br />
<br />
I'm still here on Blogger (another "free" service). It's part of Google, and Google is another collector and reseller of my data, I know. Especially when I use Android, Drive, or Maps, or many other services. I use Twitter, too. Twitter is short form (mostly), and I seem to be better able to filter what I read. And there's Amazon, and there's even Reddit, and more.<br />
<br />
<br />Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-66139505220527033102019-04-06T16:37:00.000-04:002019-04-06T16:40:29.275-04:00Antennas, cheap<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-ZfhLi8XmacE/XKkNDHjCLXI/AAAAAAAArSI/8pnrzHHXt502XfprAjekJ9-HDQcVb9drgCLcBGAs/s1600/DSC_0014.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1000" data-original-width="1504" height="425" src="https://3.bp.blogspot.com/-ZfhLi8XmacE/XKkNDHjCLXI/AAAAAAAArSI/8pnrzHHXt502XfprAjekJ9-HDQcVb9drgCLcBGAs/s640/DSC_0014.JPG" width="600" /></a></div>
<br />
We are going to be taking down the ham antennas, because we're moving to a retirement community. This happens.<br />
<br />
On the positive side, our new community is interested in supporting amateur radio (to some extent?), and we may have a chance to develop a new "farm". See my article on <a href="https://aa6e.net/senior-living-for-hams" target="_blank">ham radio in retirement communities</a>.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-33997452942239939302018-08-12T16:53:00.001-04:002018-08-12T17:03:05.438-04:00Some AREDN progress<div class="separator" style="clear: both; text-align: center;">
<a href="https://arednmesh.org/" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;" target="_blank"><img border="0" data-original-height="144" data-original-width="295" height="97" src="https://1.bp.blogspot.com/-BiJVViJ49Qw/W3BdoaKQyhI/AAAAAAAAm2U/HN-qHRAgewMp7zgQJ_Oe85qL1wiL3DIkgCLcBGAs/s200/AREDN-Final-Logo_0.jpg" width="200" /></a></div>
We have been working on bringing up an AREDN mesh network at ARRL HQ and here at AA6E. AREDN, the <a href="https://www.arednmesh.org/" target="_blank">Amateur Radio Emergency Data Network</a>, has developed from the HSMM project (High Speed Multimedia, see web sites <a href="http://www.hsmm-mesh.org/" target="_blank">here</a> and <a href="https://en.wikipedia.org/wiki/High-speed_multimedia_radio" target="_blank">here</a>.) AREDN supports a "<a href="https://en.wikipedia.org/wiki/Mesh_networking" target="_blank">mesh network</a>" running under FCC Part 97 (Amateur Radio) rules on allocated frequencies some of which are close to standard "WiFi" (2.4 and 5 GHz).<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-KUUyTY1a-cA/W3CUUbASM8I/AAAAAAAAm2k/MpyUlOeHNO8g1AAnorEHJJYNVZ762ULzQCLcBGAs/s1600/IMG_20180812_113111.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1200" height="200" src="https://4.bp.blogspot.com/-KUUyTY1a-cA/W3CUUbASM8I/AAAAAAAAm2k/MpyUlOeHNO8g1AAnorEHJJYNVZ762ULzQCLcBGAs/s200/IMG_20180812_113111.jpg" width="150" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ubiquity Nanostation Loco M5 AREDN node</td></tr>
</tbody></table>
<b>What is mesh networking?</b> Simplified, it is a way to interconnect more or less randomly located network nodes that may come and go, such as in response to emergency requirements. Each node may originate data or may relay data to adjacent nodes. Networking software automatically routes packets by the best paths through the mesh, from source to destination. Certain mesh nodes may have gateways to other networks, such as the commercial Internet. Certain nodes may have special servers (web, email, file, etc.) that are made available to the network. In general, AREDN mesh networks are set up to be independent of commercial communications services as much as practical.<br />
<br />
At AA6E and ARRL, we have implemented a test network to learn about AREDN technology and to try out configurations that might support a variety of routine and emergency communications needs. The first setup uses up to 4 Ubiquiti NanoStation Loco M5 devices with custom AREDN software. These form a small-scale mesh, currently all within the ARRL Laboratory.<br />
<br />
A test bed setup at AA6E uses two of these nodes to demonstrate network capabilities. Below is a block diagram of the tested network.<br />
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<a href="https://1.bp.blogspot.com/-VZ15kurYxqU/W3CU_Xe0ayI/AAAAAAAAm2s/5PD372NCzEUb2aBl7IlDrk9jCI8OBVHDgCLcBGAs/s1600/aredn-testbed.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="324" data-original-width="576" src="https://1.bp.blogspot.com/-VZ15kurYxqU/W3CU_Xe0ayI/AAAAAAAAm2s/5PD372NCzEUb2aBl7IlDrk9jCI8OBVHDgCLcBGAs/s1600/aredn-testbed.png" /></a></div>
The AREDN network is at the right. One Loco M5 device supports a laptop computer (where I am writing this article). Through the radio link at 5.9 GHz, the two Locos support a bit stream of up to about 30 Mb/s using a 10 MHz RF channel. As seen by the laptop, the Loco provides an IP address through its own DHCP server. Traffic is routed to the second Loco, which in turn supports two VLANs (partitions of a single Ethernet connection). One is a generic "LAN" connection that will support Ethernet devices like the Raspberry Pi which is acting as a small webserver for our test. The Pi will also support SSH, VNC, and many other services as needed.<br />
<br />
The second switch port supports another VLAN for "WAN" connections, e.g., to the Internet. Through the Internet router it obtains an address on the household LAN.<br />
<br />
<br />
<table>
<tbody>
<tr><td><a href="https://3.bp.blogspot.com/-hFsIl71ZsJE/W3CXo4BeS2I/AAAAAAAAm24/ptBAFBX9NKsbPEJIyXwFeMBTb6K8EM2GwCLcBGAs/s1600/IMG_20180812_113150.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="200" src="https://3.bp.blogspot.com/-hFsIl71ZsJE/W3CXo4BeS2I/AAAAAAAAm24/ptBAFBX9NKsbPEJIyXwFeMBTb6K8EM2GwCLcBGAs/s200/IMG_20180812_113150.jpg" width="150" /></a><a href="https://2.bp.blogspot.com/-N_jK-hHgZB8/W3CXsbMSHKI/AAAAAAAAm28/fLnEnT4bPnI-oTkcepJBGQeG850AJSu3QCLcBGAs/s1600/IMG_20180812_113125.jpg" imageanchor="1" style="margin-bottom: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="1600" data-original-width="1200" height="200" src="https://2.bp.blogspot.com/-N_jK-hHgZB8/W3CXsbMSHKI/AAAAAAAAm28/fLnEnT4bPnI-oTkcepJBGQeG850AJSu3QCLcBGAs/s200/IMG_20180812_113125.jpg" width="150" /></a></td><td><a href="https://1.bp.blogspot.com/-cB5JNADiQq8/W3CXylHLLJI/AAAAAAAAm3A/H5DjWA4S3dw5XXQ7qrpdvEqnA8B0pAa1QCLcBGAs/s1600/IMG_20180812_113303.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="1600" data-original-width="1200" height="200" src="https://1.bp.blogspot.com/-cB5JNADiQq8/W3CXylHLLJI/AAAAAAAAm3A/H5DjWA4S3dw5XXQ7qrpdvEqnA8B0pAa1QCLcBGAs/s200/IMG_20180812_113303.jpg" width="150" /></a></td></tr>
</tbody></table>
<br />
L to R: Raspberry Pi 3; Netgear GS105E VLAN-aware switch; Toshiba Laptop<br />
<br />
This setup demonstrates many of the functions we would need in an operational network. We still need to set up facilities for node to node bridging that we would need to build up a larger network, supporting multiple operating bands, etc.<br />
<br />
There is nothing "new" here. It's all been done elsewhere, but we are climbing our learning curve.<br />
<br />Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-2101500302544238662018-04-28T23:19:00.000-04:002018-04-29T11:53:18.789-04:00Gone Streaming. Sorry, Comcast.<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-U9J0_G3JKyI/WuU2jFxVy4I/AAAAAAAAmTk/g9p8dl1lahMMPCrPO_WkShaJn6U8yb30wCLcBGAs/s1600/chart.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="572" data-original-width="711" height="160" src="https://4.bp.blogspot.com/-U9J0_G3JKyI/WuU2jFxVy4I/AAAAAAAAmTk/g9p8dl1lahMMPCrPO_WkShaJn6U8yb30wCLcBGAs/s200/chart.png" width="200" /></a></div>
So sorry to hear that the cable TV industry is suffering because of the growing defection to streaming media services. See this recent <a href="https://www.fiercecable.com/cable/pay-tv-bills-up-74-since-2000-leading-cause-cord-cutting-kagan-says" target="_blank">Fierce Cable article</a>. We seem to be entering a meltdown, where increasing cable prices encourage more of us to "cut the cable" and go to streaming solutions. That means that cable companies have to increase their rates, which leads to more defections.<br />
<br />
You don't want to be the last one to switch over in a game like this.<br />
<br />
We aren't the first by any means, but our sky-high bill finally got to be too much when the last of our introductory discounts disappeared.<br />
<br />
Technically, the Comcast service in our area is very good. Internet performance has inched up over 250 Mb/s. Unfortunately, the monthly charge is running around $1 per Mb/s.<br />
<br />
So we had an abundance of bandwidth and a similar abundance of channels -- most of which we never used. The Internet bandwidth is sweet when I want to download a new Linux DVD every 6 months, but how much is that really worth?<br />
<br />
<b>TL;DR.</b> We have just dropped cable video and phone service and cut back our Internet speed to 60 Mb/s -- quite enough for our small household. These changes cut our Comcast payment by 70%!<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-nAz77Y7TYkM/WuU1z1vbj2I/AAAAAAAAmTc/tVsQFPmOSJ8w0Sm0QQNLfF6N0kXGnGftgCLcBGAs/s1600/Smart-tv-online-streaming-movie-video.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="336" data-original-width="540" height="199" src="https://4.bp.blogspot.com/-nAz77Y7TYkM/WuU1z1vbj2I/AAAAAAAAmTc/tVsQFPmOSJ8w0Sm0QQNLfF6N0kXGnGftgCLcBGAs/s320/Smart-tv-online-streaming-movie-video.jpg" width="320" /></a></div>
The new system is built on a Netgear CM600 modem, an Asus RT-N66U WiFi router, an Ooma Telo VOIP box, and a Roku streaming device. (Our nice Sony HDTV predates "smart TV".*) In addition, we're watching more over-the-air TV, mainly to get the PBS Newshour live. (PBS hasn't figured out how to live stream, it appears.) In this location, we need an amplified antenna that mostly works for us indoors, but it will need to be installed outdoors for solid performance.<br />
<br />
The thorny issue now is how to make sense of the many streaming services. People worry about what will be happening without "net neutrality". The Internet is likely to fragment into walled gardens. As others have pointed out, this already is happening in the streaming market. Do I want Amazon Prime, Netflix, Hulu, CBS Now, etc.? There are several providers for live streaming TV channels, too. Each of these has some interesting content. Even if I didn't mind paying for all of them, the data management gets to be overwhelming. There is no simple navigation or program guide I know of that crosses those boundaries.<br />
<br />
Brave new world? Chaos? All of that. Glad to help the cable industry find its destiny.<br />
<br />
<b>* Smart TV:</b> I worry that the "smarts" get obsolete well before the "TV" does. Integrating them should help simplify the user experience, but the quick obsolescence is a worry.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-44569611288142258452018-04-09T00:26:00.000-04:002018-04-09T00:26:41.823-04:00Frequency Measurement Test<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/--O_j-yGFaAk/Wsp8Vg31cnI/AAAAAAAAmKc/_72nSa8DX1wi5c1deWnqdz35kTqJBVk5QCLcBGAs/s1600/bc221detail.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="171" data-original-width="187" src="https://4.bp.blogspot.com/--O_j-yGFaAk/Wsp8Vg31cnI/AAAAAAAAmKc/_72nSa8DX1wi5c1deWnqdz35kTqJBVk5QCLcBGAs/s1600/bc221detail.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The old way: BC-221 meter</td></tr>
</tbody></table>
April 6, 2018 was my second attempt at the <a href="http://www.arrl.org/frequency-measuring-test" target="_blank">ARRL Frequency Measurement Test</a> in which amateurs are invited to measure the exact frequency of a test signal transmitted from a central site. The first time, years ago, I came out OK with a manual procedure using my old TenTec Orion radio, carefully calibrated against the US <a href="https://en.wikipedia.org/wiki/WWV_(radio_station)" target="_blank">NIST Time and Frequency Station WWV</a>. Measurement accuracy depended on an imprecise estimate of the WWV calibration compounded by an imprecise measurement of the W1AW test signal.<br />
<br />
This time, we've upped the ante, using the <a href="http://www.flexradio.com/amateur-products/flex-6000-signature-series/flex-6500/" target="_blank">FlexRadio Systems 6500</a> transceiver (an <a href="https://en.wikipedia.org/wiki/Software-defined_radio" target="_blank">SDR radio</a>) with its <a href="https://en.wikipedia.org/wiki/GPS_disciplined_oscillator" target="_blank">GPS Disciplined Oscillator</a> as a master frequency reference. The reference is said to be accurate to some parts in 10<sup>12</sup>, though we have no way to verify that number at this time. If the receiver is tuned to a known frequency just below the test signal in upper sideband mode, so that the received signal shows up as an "audio" tone. (In this SDR receiver, there is no "audio", since everything is digital. That bypasses various audio measurement problems that might otherwise have cropped up.) The <a href="https://en.wikipedia.org/wiki/Fldigi" target="_blank">fldigi software package</a> is used in its "spectral analysis" mode to accurately measure the offset, combined with the known local oscillator tuning, to yield a good measurement of the unknown RF frequency. The software outputs an Excel CSV file that records time and best-fit frequency each second.<br />
<br />
Here in Branford, CT the antenna for 20 M is a 3-element SteppIR at 40 ft pointed west. For 40 M and 80 M the antennas were dipoles oriented NW-SE, more or less.<br />
<br />
This exercise involved transmissions on the 20, 40, and 80 Meter amateur bands from K5CM in eastern Oklahoma.<br />
<br />
<b>RESULTS</b><br />
<br />
The actual numbers as transmitted are reported on the <a href="http://www.b4h.net/fmt/fmtresults201804.php" target="_blank">FMT results page for 2018</a>.<br />
<br />
<table>
<tbody>
<tr><td><span style="font-family: "courier new" , "courier" , monospace;">B<b>and</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> F Measured (Hz)</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> F Actual (Hz)</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> Error (Hz)</b></span></td></tr>
<tr><td><span style="font-family: "courier new" , "courier" , monospace;"><b>20M</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> 14,121,963.42 +/- .08*</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> 14,121,963.34</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> +0.08</b></span></td> </tr>
<tr><td><span style="font-family: "courier new" , "courier" , monospace;"><b>40M</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> 7,064,257.09 +/- .20*</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> 7,064,257.06</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> +0.03</b></span></td></tr>
<tr><td><span style="font-family: "courier new" , "courier" , monospace;"><b>80M</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> 3,598,169.5**</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> 3,598,169.73</b></span></td> <td><span style="font-family: "courier new" , "courier" , monospace;"><b> -0.23</b></span></td></tr>
</tbody></table>
<br />
* Error bar quoted is 1/2 the total peak-to-peak frequency excursion in the 2 minute test transmission.<br />
<div>
** 80M results were compromised by a data handling problem. Precision is reduced, and an error bar could not be estimated.</div>
<div>
<br /></div>
<div>
WWV reported geomagnetic conditions Kp=2 and Ap=9 during the test.</div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<a href="https://2.bp.blogspot.com/-2t01Bc6iiqE/WsqDKMaQABI/AAAAAAAAmKw/N49qPXMf3tcPnqQ5skrfnrzkDUMniIgZQCLcBGAs/s1600/evens20.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="419" data-original-width="604" height="221" src="https://2.bp.blogspot.com/-2t01Bc6iiqE/WsqDKMaQABI/AAAAAAAAmKw/N49qPXMf3tcPnqQ5skrfnrzkDUMniIgZQCLcBGAs/s320/evens20.png" width="320" /></a>The graphs at the right show the (almost) raw data measured on the 20 and 40 M bands. The 20 M signal strength was quite good, touching S9+10 dB, and the measurements appear largely free of statistical noise. The major feature is an sine-like variation that presumably reflects true changes in the signal data path. I believe that the "glitch" at the left is an artifact of an initial mis-adjustment of the radio. It was left out of the average calculation. (Ignore the "even samples" tag.)<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-W9xdUwUJt0A/WsqDKMv-_jI/AAAAAAAAmK0/GhFMXDaAeIMOonpTt_NkRSMr_y1yREboACLcBGAs/s1600/40m-chart.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="340" data-original-width="605" height="179" src="https://2.bp.blogspot.com/-W9xdUwUJt0A/WsqDKMv-_jI/AAAAAAAAmK0/GhFMXDaAeIMOonpTt_NkRSMr_y1yREboACLcBGAs/s320/40m-chart.png" width="320" /></a></div>
The 40 M signal was about S8, i.e. up to 16 dB weaker than on 20 M. This probably produced much of the short-period noise on the graph. However, we might also expect the ionosphere to produce more variability on the lower frequency.<br />
<br />
For 20 and 40, we calculate a simple average frequency, after eliminating the initial points on 20 M. Note that we might have done better of we could weight the samples according to instantaneous signal strength. There are two sharp dips in the 40 M data that may well have arisen from deep signal fades. If they were eliminated, we would have a slightly higher frequency estimate, which would have <u>increased</u> our final error value.<br />
<div>
<br /></div>
<div>
Because of the problems with the 80 M data, there is no meaningful graph to plot for that band.</div>
<div>
<br /></div>
<div>
<b>DISCUSSION</b></div>
<div>
<br />
The final error (Measured - Actual) is under 0.1 Hz for the two fully analyzed bands, while the 80 M error is -0.23 Hz based on fewer data points. These are surprisingly good, leaving relatively little room for improvement given the "noisiness" of ionospheric propagation conditions. Presumably, we might get a somewhat better measurement if we had a longer test run, perhaps 5 or 10 minutes or more, or if we got lucky and had a period of super-stability in the ionosphere.</div>
Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-22319893556119735712018-03-04T18:44:00.000-05:002018-03-04T18:44:53.555-05:00Annals of Provisional Engineering (GPS)<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-rAtlO-C-unM/WpyBgDY8KmI/AAAAAAAAloI/8qbO77PnOj8kx9FXrNS4AqCchx1HZ-2lgCLcBGAs/s1600/GPS_ant.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1600" data-original-width="1091" height="320" src="https://1.bp.blogspot.com/-rAtlO-C-unM/WpyBgDY8KmI/AAAAAAAAloI/8qbO77PnOj8kx9FXrNS4AqCchx1HZ-2lgCLcBGAs/s320/GPS_ant.jpg" width="218" /></a></div>
The GPS antenna provided by Flex Radio Systems for their <a href="http://blog.aa6e.net/2018/02/gps-is-looking-up.html" target="_blank">GPSDO add-on module</a> is an indoor-style "biscuit" measuring about 1 x 2 inches. It comes with an adhesive patch that is meant to secure it to an indoor window.<br />
<br />
My available window had a rather marginal sky view, and the GPS was not locking up very well. So before going out for a "professional" outdoor antenna, it seemed a good idea to try the one on hand.<br />
<br />
Having achieved a certain age, I have a lot of containers for medical prescriptions that I've been saving for some reason. One of the larger ones nicely fits the biscuit, along with some bubble wrap as a filler. The cap used to seal the contents quite well, and it does so even after being sliced to allow the RG-174/U style coax to pass through. (The coax is permanently attached to the antenna.)<br />
<br />
Long story short -- the antenna and "radome" attaches to a convenient metal mast about 5 feet off the ground, facing upward. The duct tape system won't last forever, but it's fine for a temporary setup. GPS reception is now quite solid.<br />
<br />
It has survived a recent "bomb cyclone" wind and rain event that downed a fair number of trees in our area.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-790646399256867032018-02-23T13:30:00.000-05:002018-02-28T23:04:48.535-05:00GPS is Looking Up<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-0HDWIr4btoE/WpBGGPC4XcI/AAAAAAAAlj4/l0J2BXOjHIk1jhTY8EARpiip5ENbOcedACLcBGAs/s1600/Flex_GPSDO.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1200" height="400" src="https://4.bp.blogspot.com/-0HDWIr4btoE/WpBGGPC4XcI/AAAAAAAAlj4/l0J2BXOjHIk1jhTY8EARpiip5ENbOcedACLcBGAs/s400/Flex_GPSDO.jpg" width="300" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">GPSDO unit in Flex 6500, cover removed</td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-5LfcCrNEi1I/WpBGFmfhhtI/AAAAAAAAlj0/ztw0-NDIrI4fj9D0VMA9QW8s8t4aT3CjwCLcBGAs/s1600/Flex_GPSDO_socket.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1200" height="200" src="https://1.bp.blogspot.com/-5LfcCrNEi1I/WpBGFmfhhtI/AAAAAAAAlj0/ztw0-NDIrI4fj9D0VMA9QW8s8t4aT3CjwCLcBGAs/s200/Flex_GPSDO_socket.jpg" width="150" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Flex 6500 GPSDO attachment area</td></tr>
</tbody></table>
This is a bad news, good news story. Last year, I purchased the GPS Disciplined Oscillator (GPSDO) option for my Flex 6500 transceiver. This is meant to be a user-installable device that receives the <a href="https://en.wikipedia.org/wiki/Global_Positioning_System" target="_blank">GPS</a> signal (1.2 - 1.5 GHz), derives very accurate time (UTC) and frequency (10 MHz) for use by the transceiver. And, of course, it reports your geographical position (latitude, longitude, and height above sea level) and speed.<br />
<br />
As you can see from the photo, the GPSDO appears to be based on custom version of a Jackson Labs GPSOCXO (Oven Stabilized Crystal Oscillator) module. It's the green board that attaches to a blue Flex-produced interface board. The <a href="http://www.jackson-labs.com/assets/downloads/GPSOCXO_Specsheet.pdf" target="_blank">GPSOCXO specifications</a> are available as a PDF, while <a href="http://www.jackson-labs.com/index.php/products/gps_ocxo" target="_blank">general information is here</a>.<br />
<br />
I am now on my third GPS unit. The first was a "reconditioned" unit, because new units were then in short supply. It never worked for me -- it would not detect satellites. Flex then supplied another unit, which worked well. It detected satellites, locked up, and appeared to deliver good frequency stability. But, over time, it grew hard of hearing. It dropped out of lock more and more and finally would not lock at all, though it continued to supply 10 MHz in "holdover" mode.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-UmcROJBf0Bk/WpBZB_P7ttI/AAAAAAAAlkM/yRm6g7wxyEYwauOXaYRMIYFURddLu6-QACLcBGAs/s1600/ssdr_gps.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="369" data-original-width="450" height="327" src="https://4.bp.blogspot.com/-UmcROJBf0Bk/WpBZB_P7ttI/AAAAAAAAlkM/yRm6g7wxyEYwauOXaYRMIYFURddLu6-QACLcBGAs/s400/ssdr_gps.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">GPS Status, SSDR software</td></tr>
</tbody></table>
Fortunately, my unit failed just before the warranty period expired, so I was able to get a replacement without (financial) trouble. Now my third (and hopefully last) unit is perking along. The good news!<br />
<br />
Currently, I use the Flex-supplied simple "patch" active antenna attached to a nearby west-facing window. Typically, I track 7-8 satellites out of 10-11 "visible". We might be able to squeeze out more performance by installing a larger outdoor antenna.<br />
<br />
<br style="clear: both;" />
<b>Why use GPS?
</b><br />
<br />
The standard Flex TCXO is fine for nearly any application in the HF/6 bands. So why go for GPS? Because it's there. Because, as an erstwhile <a href="https://en.wikipedia.org/wiki/Very-long-baseline_interferometry" target="_blank">VLBI</a> radio astronomer, I am interested in time and frequency standards. (See <a href="http://www.leapsecond.com/time-nuts.htm" target="_blank">time-nuts</a>.)<br />
<br />
There's a good case to use GPS stabilization for VHF/UHF/microwave work, where oscillators are typically locked to a high harmonic of a 10 MHz standard. A portable GPS time standard is also useful for operating modes like JT65 or FT8 that require it. (Although, with care, WWV's HF time signals are also good enough.) Unfortunately, Flex does not yet offer time synchronization services for the radio shack. Maybe in the future.<br />
<br />
<b><span style="font-size: large;">Note added:</span></b> So after 24 hours of operation, we lose lock. Of course there's a light cold rain and heavy overcast. Hoping it's the weather. (But my cell phone GPS is working fine...)<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-xtBIC_Swegs/WpLjIOY0ksI/AAAAAAAAlk0/4fkHIF-CIhcekP1vMlCBg0v2Fa0KxFwqQCLcBGAs/s1600/gpsdo_connector.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="153" data-original-width="364" height="134" src="https://4.bp.blogspot.com/-xtBIC_Swegs/WpLjIOY0ksI/AAAAAAAAlk0/4fkHIF-CIhcekP1vMlCBg0v2Fa0KxFwqQCLcBGAs/s320/gpsdo_connector.png" width="320" /></a></div>
<b><span style="font-size: large;">More:</span></b> It's looking like this was a connector problem. (Electronics troubles often are.) If you look at the attachment area photo (here enlarged), you will notice the 10 golden spring terminals. These touch gold-plated tabs on the GPSDO PC board. They provide all the power and computer signalling. It's not apparent in this photo, but if you look edge-on with a magnifier, you might notice that the tiny springs are not all in perfect alignment vertically. It seems that one or more of them were not making good contact. (The PC board screws down on the alignment posts, and the contact pressure has to be "sufficient" -- whatever that may be.) After a little fiddling with a tiny screwdriver, along with an alcohol cleaning, the GPSDO seems to be back in operation. For good measure, I also replaced the RF input cable.<br />
<br />
We will see if things are now stable. It has been OK for 12 hours! I have to say that the GPSDO-to-mainboard connection system is not the most robust. It looks like we had a marginally OK connection at first, which degraded after some temperature cycling or minor vibration. A traditional connector (with pins and sockets) would have been much more reliable, though a bit more expensive and less elegant.<br />
<br />
It's possible that all this last year's GPS travails came down to that connector, but I can't be sure.<br />
<br />
<b><span style="font-size: large;">Yet more: </span></b>After the connector fix, the GPSDO seems to be much healthier, but we were still experiencing occasional drop-outs (loss of sync). Moving the antenna outdoors seems to make a big improvement. The view is much less obstructed. I've made a stab at a weather-tight case for the little biscuit antenna using a large size prescription container and taped the whole thing to a nearby mast at about 5 ft elevation. We seem to be getting good sync about 10 minutes after a warm start, which is a lot better than before. <br />
<br />
Sadly, the Flex module does not give any direct indication of GPS signal strength. There is also no way to log loss of sync events. Maybe this is a good time to start writing Python code to access GPS status from the radio via TCP/IP. I would like to log performance for a few days as a final system check.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-84445958858058602362017-10-31T15:40:00.001-04:002017-11-01T09:18:48.957-04:00A Little Audio<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-Ij_m-U21jNw/WfjIA_3ZynI/AAAAAAAAkvE/Fgn9_0zYdcohGDtzFVf0Kz72MxkvEhVhQCLcBGAs/s1600/new_audio.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="179" data-original-width="600" height="118" src="https://4.bp.blogspot.com/-Ij_m-U21jNw/WfjIA_3ZynI/AAAAAAAAkvE/Fgn9_0zYdcohGDtzFVf0Kz72MxkvEhVhQCLcBGAs/s400/new_audio.png" width="400" /></a></div>
This is not "high" tech, but finding a solution took a little while. The AA6E station, for today's purpose, consists of a Windows 10 PC (the Intel NUC), a FlexRadio Flex-6500, and two compact bookshelf loudspeakers.<br />
<br />
The usual solution these days for audio setups is to use "powered speakers" for computer audio and possibly for transceiver audio. But these have problems for me:<br />
<ol>
<li>For HF Amateur Radio, powered speakers generally are too sensitive to the RF environment and require ferrite suppression.</li>
<li>Powered speakers generally only offer a few feet of cabling between speakers, which is fine for your desktop but not so good if you want to fill a room with audio.</li>
<li>It's awkward to support independent speaker systems for the radio and for the computer. They take up space, and they make for lots of cabling.</li>
<li>Higher end powered speakers do a fair job with audio fidelity, but not as good as good conventional speaker components.</li>
</ol>
In my case, I'm starting with these nice inherited speakers (thanks to son Eric!) and I'm working backward. You need a basic audio amplifier. These aren't as common as they once were. There are some interesting very cheap "Class D" switching amplifiers. I tried one (the Lepy LP-2020A). It did OK with the audio, but it lacked multiple inputs, and, worse, it produced very strong VHF emissions that wiped out 2 meters for me, even after adding chokes.<br />
<br />
I sat on this project for a while, until I ran across a family of simple audio amplifiers by AudioSource. They offer the <a href="http://www.audiosource.net/product/amp100vs/" target="_blank">AMP100VS</a>, which gives 50 W per stereo channel. That's more than I need, but you only live once. Amazon has it for $110.<br />
<br />
The system (diagrammed above) provides several unexpected features:<br />
<ul>
<li><b>Auto On-Off.</b> The amp can be set to power on whenever an audio input signal appears. There's about a 3 second delay for turn-on. Power shuts down after 5 minutes with no input. This feature saves us having to provide switched AC power. In the standby mode, the amp draws 8 W from the line, compared to about 17 W for power on idling. You can argue whether that's a worthwhile saving! (Power can alternatively be controlled by a 12 V DC signal.)</li>
<li><b>Audio Interrupt.</b> This amp is apparently designed for the commercial public address market, where you might have background music that is occasionally interrupted by "Attention K-Mart Shoppers". In my case, it is convenient to allow the radio's output to interrupt the computer's output, so I don't need an audio switch or mixer.</li>
</ul>
This is low tech, as promised, but it sounds fine and solves a knotty little problem.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-34741909285477136512017-10-02T21:49:00.000-04:002017-10-03T21:03:19.897-04:00A little NUC on my desk<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-uGh31RmJkyg/WdKO6sMmfVI/AAAAAAAAkoY/si1rsXUszR4iphiq9vmTURsUG8NK8H-lQCLcBGAs/s1600/nuc-ssdr.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="480" data-original-width="640" height="300" src="https://3.bp.blogspot.com/-uGh31RmJkyg/WdKO6sMmfVI/AAAAAAAAkoY/si1rsXUszR4iphiq9vmTURsUG8NK8H-lQCLcBGAs/s400/nuc-ssdr.png" width="400" /></a></div>
<br />
When my 8 year old computer, home built with a Core i7-920 processor, began freezing up randomly, a new generation computer was in order. The only application I normally use that takes significant computing power is <a href="http://www.flexradio.com/amateur-products/flex-6000-signature-series/smartsdr/" target="_blank">FlexRadio's Smart SDR for Windows</a> that needs to control the <a href="http://www.flexradio.com/amateur-products/flex-6000-signature-series/flex-6500/" target="_blank">Flex 6500 SDR transceiver</a>.<br />
<br />
Recent SSDR versions are much less demanding than they used to be, so maybe I could make do with a "downgrade" to a Core i5 system. Intel processors divide broadly between "i3" (dual core), "i5 (dual core, with hypterthreading yielding 4 threads), and "i7" (quad core, 8 threads). Of course, the later chips ("generations") in each category will be a lot more powerful than the earlier ones.<br />
<br />
After some debate, I selected a Intel NUC (next unit of computing) tiny computer configuration in "kit" form. You need to supply your own SSD (solid state disk) or hard drive and your own DDR4 RAM. The NUC is available in quite a few versions, but I ended up with the <a href="https://www.intel.com/content/www/us/en/products/boards-kits/nuc/kits/nuc7i5bnh.html" target="_blank">Intel BOXNUC7I5BNH</a> kit, which is a "7th generation" i5 box with room to add a 2.5 in. SSD or HD.<br />
<br />
I installed a Samsung 960 EVO Series - 250GB PCIe NVMe internal SSD, which uses the (relatively) new <a href="https://en.wikipedia.org/wiki/M.2" target="_blank">M.2 interface</a> and leaves the 2.5 in. bay free for the future. Two 4GB DDR4 RAM chips complete the kit. Assembly is trivial, if you're at all familiar with computer innards. Installing Windows 10 Home from a USB memory stick was quick. Transferring data and software from the old system was simplified by staging files onto an external USB hard drive.<br />
<br />
After all that, we have a very fast little computer. The Passmark benchmark comes out at 3,644, which is roughly 60% of the score of the old i7-920 with GT640 graphics -- but with half the cores and only on-chip graphics. The NUC is happy to drive my two HDMI displays, although the second display requires a Thunderbolt/USB-C to HDMI adapter cable. SSD I/O performance is blazing!<br />
<br />
But what about Flex SSDR? That's the primary app for this computer -- when I'm not using the Flex Maestro controller. Here are some results:<br />
<br />
<center>
<table style="text-align: center;">
<tbody>
<tr><td><div style="text-align: center;">
<b>Panadaptors</b> | </div>
</td><td><div style="text-align: center;">
<b>window size</b> | </div>
</td><td><div style="text-align: center;">
<b>CPU utilization</b> | </div>
</td><td><div style="text-align: center;">
<b>Network Mb/s</b></div>
</td></tr>
<tr align="center"><td><div style="text-align: center;">
1</div>
</td> <td><div style="text-align: center;">
1/4</div>
</td> <td><div style="text-align: center;">
15%</div>
</td> <td><div style="text-align: center;">
2.4</div>
</td> </tr>
<tr align="center"><td><div style="text-align: center;">
1</div>
</td> <td><div style="text-align: center;">
full</div>
</td> <td><div style="text-align: center;">
20%</div>
</td> <td><div style="text-align: center;">
2.7</div>
</td> </tr>
<tr align="center"><td><div style="text-align: center;">
4</div>
</td> <td><div style="text-align: center;">
full</div>
</td> <td><div style="text-align: center;">
33%</div>
</td> <td><div style="text-align: center;">
6.0</div>
</td> </tr>
<tr align="center"><td><div style="text-align: center;">
4*</div>
</td> <td><div style="text-align: center;">
full</div>
</td> <td><div style="text-align: center;">
44%</div>
</td> <td><div style="text-align: center;">
9.4</div>
</td> </tr>
<tr align="center"><td><div style="text-align: center;">
4*</div>
</td> <td><div style="text-align: center;">
1/4</div>
</td> <td><div style="text-align: center;">
36%</div>
</td> <td><div style="text-align: center;">
7.2</div>
</td> </tr>
</tbody></table>
</center>
<div style="text-align: left;">
<div style="text-align: center;">
(* maximize spectrum frames per second and waterfall rate)</div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
The worst case CPU load (44% across the 4 i5 threads) seems to be a comfortable number. The Flex 6700, on the other hand, with its maximum 8 panadapters might have trouble, if that's your operating style.</div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
The NUC handles the required load with capacity to spare. It uses much less power to run and has only about 1/60 the volume of the old system, fitting easily on the desk.</div>
<div style="text-align: left;">
<br /></div>
</div>
Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-5131408047583823392017-09-08T10:57:00.001-04:002017-09-08T10:58:16.940-04:00Don't believe everything you read (Kp=5)<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-sDcJi4CsIoQ/WbKsyNSKqSI/AAAAAAAAkTU/UDVCsn2siz0wdxHMOnXA7CLmPO1tvgvyACLcBGAs/s1600/k5.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="222" data-original-width="281" src="https://2.bp.blogspot.com/-sDcJi4CsIoQ/WbKsyNSKqSI/AAAAAAAAkTU/UDVCsn2siz0wdxHMOnXA7CLmPO1tvgvyACLcBGAs/s1600/k5.png" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
(tnx N3KL, NASA)</div>
<div class="separator" style="clear: both; text-align: left;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
The news is all about the "Major Solar (Geomagnetic) Storm" we are having. Points:</div>
<ul>
<li>No aurora visible last night (lat 41 deg), but Moon was very bright.</li>
<li>Kp (Planetary K index) is supposed to be 5 now (quite high), and it was up to 8 last night. But the 20 meter ham band is hopping. I just bagged my first digital T77 (San Marino).</li>
<li>If it weren't for the news, I'd say 20 meter (14 MHz) conditions are fairly normal, but 15 and 17 meters (21 and 18 MHz) are largely dead.</li>
</ul>
<div>
Sometimes it's better not to know too much.</div>
Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-61717582495766081682017-09-06T09:26:00.000-04:002017-09-06T09:28:30.729-04:00End of the world, coming into view?<div class="separator" style="clear: both; text-align: left;">
Solar cataclysm (for shortwave radio folks) is happening right now.</div>
<div class="separator" style="clear: both; text-align: left;">
<br /></div>
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<a href="https://3.bp.blogspot.com/-bufaaEV8TdE/Wa_02mTKo5I/AAAAAAAAkRo/wj1X7LPtH4c_pTyE1-ovzXUScQwBPVlFACLcBGAs/s1600/dregion.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="442" data-original-width="728" height="242" src="https://3.bp.blogspot.com/-bufaaEV8TdE/Wa_02mTKo5I/AAAAAAAAkRo/wj1X7LPtH4c_pTyE1-ovzXUScQwBPVlFACLcBGAs/s400/dregion.png" width="400" /></a></div>
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The red shows the absorption of radio waves around the globe, with the center in the current sub-solar point (where it is noon).</div>
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<a href="https://2.bp.blogspot.com/-_W_HLfjBJ-M/Wa_06HoqRSI/AAAAAAAAkRs/S4JheT_i1Y8gJ4UVI7afGYGqyr9FR1WOwCLcBGAs/s1600/r3.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="224" data-original-width="694" height="128" src="https://2.bp.blogspot.com/-_W_HLfjBJ-M/Wa_06HoqRSI/AAAAAAAAkRs/S4JheT_i1Y8gJ4UVI7afGYGqyr9FR1WOwCLcBGAs/s400/r3.png" width="400" /></a></div>
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We have "R3" radio blackout conditions. (All from <a href="http://www.swpc.noaa.gov/">http://www.swpc.noaa.gov</a>)</div>
<br />
In addition to this, we have a "CME" (coronal mass ejection) of high-speed charged particles generated by a <b>previous</b> flare event that is supposed to hit us today, causing a geomagnetic storm that should further screw up the HF airwaves. You probably won't lose your electric power, however, but you might get to see the aurora borealis tonight -- if it's not raining cats and dogs.<br />
<br />
And, there are big thunderstorms outside.<br />
<br />
And, there are two big hurricanes out there somewhere -- not in New England (yet) fortunately for us.<br />
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And lots of trouble coming from DC and some other world capitals.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-40918820425480793372017-08-24T12:27:00.000-04:002017-08-24T12:27:56.733-04:00Flex Remote @ ARRL HQ<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-3Td7dVZdrnY/WZ77uKLdlsI/AAAAAAAAjm4/8x4xe1U_L3UPwAsAY6F6kRO-tvUGu2_XwCLcBGAs/s1600/AA6E-remote-hq.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="768" data-original-width="1024" height="300" src="https://4.bp.blogspot.com/-3Td7dVZdrnY/WZ77uKLdlsI/AAAAAAAAjm4/8x4xe1U_L3UPwAsAY6F6kRO-tvUGu2_XwCLcBGAs/s400/AA6E-remote-hq.jpg" width="400" /></a></div>
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After a false start or two, we finally have Flex Radio's Version 2 SSDR software running. It enables easy internet remote operation from wherever, using my Flex 6500 radio installation at home and the Maestro controller.</div>
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My first successful test was using an "outside" test internet connection via my Nexus 5X cell phone in "tethering" mode, while I was still at home. It was convenient to have both local and remote sides of the connection on my operating desk. (With my data plan, I estimate the hourly running cost for remote service is about $6/hour with standard settings and not minimizing bandwidth.)</div>
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Today, we are set up in the ARRL headquarters site in Newington CT, about 40 miles from home as the crow flies. Everything seems to be working well. "59" reports from Switzerland and Spain.</div>
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At home, I have the Flex 6500 controlling the tuning of my SteppIR 3-element beam (fixed on Europe), so I can remotely operate from 20 meters down to 6 meters. Unfortunately, there is no remote pointing control -- yet. Also, no integration with digital modes or my logging system. One step at a time.</div>
Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-80186638326569171542017-08-09T16:10:00.002-04:002017-09-25T09:54:16.894-04:00What we were doing in the 80's (VLBI)<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-GDTWauBYqpE/WYtnzpQIxSI/AAAAAAAAjU8/oeyaa2s83ZEydS2H1KmsnAUIN25uGY5xgCLcBGAs/s1600/aen-mhc-dhr-mse.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1122" data-original-width="1429" height="313" src="https://1.bp.blogspot.com/-GDTWauBYqpE/WYtnzpQIxSI/AAAAAAAAjU8/oeyaa2s83ZEydS2H1KmsnAUIN25uGY5xgCLcBGAs/s400/aen-mhc-dhr-mse.png" width="400" /></a></div>
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Arthur Niell, Marshall Cohen, David Rogstad, and Martin Ewing, ca 1982</div>
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<a href="https://goo.gl/photos/mvoVCiuWwWZ4kp9g6" target="_blank">See full photo album.</a><br />
<br />
PDP-11s were hot. Helical scan video recording was just the thing for recording high-speed radio interferometer (VLBI) data. In a Caltech-JPL collaboration, we built what was then the largest correlator to process data streams from up to 5 telescopes at once -- providing correlations (fringes) between all 10 pairs. Getting any fringes at all required delicate synchronization of the telescopes (Loran C timing and Hydrogen maser frequency standards). Geometric corrections were tricky, too. You had to know the baselines between telescopes accurately, giving the delay and doppler frequency offsets. To manage all this, we had MSI-TTL logic, core memories, a PDP-11/40, and Forth software. The hardest part -- keeping those tape machines running! They were modified IVC and Ampex helical scan recorders, semi-professional. A later version of the system used standard consumer VHS recorders, which were just becoming available.<br />
<br />
One bit sampling was the choice for best signal-to-noise ratio on a broadband "continuum" radio source.<br />
<br />
<i>All this came to light again when I started digging into some old files.</i>Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-8091448046338272312017-08-09T11:00:00.000-04:002017-08-09T11:00:11.274-04:00When all else fails...<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-MxNMoBmlTLY/WYshMaNDwnI/AAAAAAAAjRI/dDcHP6bo1iUy9KqWusxJsa5KJh_W8Ib3QCLcBGAs/s1600/ke_sliderule.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="320" data-original-width="1600" height="128" src="https://4.bp.blogspot.com/-MxNMoBmlTLY/WYshMaNDwnI/AAAAAAAAjRI/dDcHP6bo1iUy9KqWusxJsa5KJh_W8Ib3QCLcBGAs/s640/ke_sliderule.jpg" width="640" /></a></div>
<br />
My Keuffel & Esser Decilon 10, model 68-1100 slide rule. There are lots of K&E sites. For example, <a href="http://www.sphere.bc.ca/test/ke-sliderule.html" target="_blank">this one</a>.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-56248907197285832862017-07-08T15:39:00.000-04:002017-07-08T15:39:19.633-04:00Things that can't be understood<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-558V9rqGMUM/WWEwJHLk7QI/AAAAAAAAjKk/WkPKqp-41y4fkzoaG0w3QGm9NUwKBw-GACLcBGAs/s1600/Altair_8800_Computer.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1349" data-original-width="1495" height="288" src="https://2.bp.blogspot.com/-558V9rqGMUM/WWEwJHLk7QI/AAAAAAAAjKk/WkPKqp-41y4fkzoaG0w3QGm9NUwKBw-GACLcBGAs/s320/Altair_8800_Computer.jpg" width="320" /></a></div>
My "fancy" homebrew computer (not pictured here) has been running nicely for about 8 years. It was big and powerful in 2009, using the new Intel Core i7-920 chip, with lots of RAM and lots of cooling. Nowadays, Gimli (as I call it) runs mostly Windows 10, with a touch of Linux.<br />
<br />
It runs up to 8 background threads simultaneously, running up some nice statistics with <a href="https://boinc.berkeley.edu/" target="_blank">BOINC</a> -- the science "@home" brokering site. Maybe we've discovered a pulsar or two, who knows?<br />
<br />
This was alongside my "real" work which has been operating my ham radio station -- running SDR radios, logging, digital mode operation, etc.<br />
<br />
That was until a few weeks ago, when Gimli started failing -- stopping suddenly with no blue screen of death or software logging, just a blank screen. I thought maybe my checkered past as an overclocking experimenter was catching up with me. I tried going back to the absolute minimal BIOS settings just in case.<br />
<br />
I starting checking out what I might need to buy to upgrade this "ancient" machine through Newegg or Amazon -- and the discussions I'd need to have with the XYL. Yes, there are many new options on the market. The biggest one might be the advent of SSD technology (Solid State Disk).<br />
<br />
As a last stand, I thought I'd check out the computer as best I could. It's practically impossible to find a fault of the kind I was having. You'd just have to replace key components one by one until it started working again.<br />
<br />
Opening the box and blowing out the dust, I started wiggling the cables and re-seating the connectors. I pulled out the two RAM modules and "cleaned" the contacts (wiping with fingers), and I plugged them back swapping their positions.<br />
<br />
Naturally when I put things all back together, Gimli came to life and hasn't crashed for a week or so now. Maybe we're go for another 7 years?<br />
<br />
Or maybe we're running on fumes.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-82676241074097702702017-07-02T18:35:00.000-04:002017-07-09T17:50:59.550-04:00Sad day at AA6E<div class="separator" style="clear: both; text-align: left;">
My FlexRadio Systems model 6500 transceiver has gotten a serious bug, dropping frequency lock periodically. It may arise from operating with the GPS Disciplined Oscillator -- and summertime high ambient operating temperatures. Back to factory it will go.</div>
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The following crude video shows how this looks when listening to WWV (15 MHz). Problem tends to develop after high duty-cycle transmission (JT65 - 50 W) for a few minutes. It sometimes goes away if the radio is left in receive for a long while (10+ minutes).</div>
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<iframe allowfullscreen="" class="YOUTUBE-iframe-video" data-thumbnail-src="https://i.ytimg.com/vi/UzhlkAokKAQ/0.jpg" frameborder="0" height="266" src="https://www.youtube.com/embed/UzhlkAokKAQ?feature=player_embedded" width="320"></iframe></div>
<br />Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-35886598742211850762017-02-25T11:40:00.000-05:002017-02-26T17:57:47.613-05:00Whatever became of Eimac?<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-UPTvyhG_jyw/WLGg27G9NJI/AAAAAAAAhFs/GqURvLKvKH0NXg_aTFtaANV3OrEVPN0zQCLcB/s1600/eimac_tubes_wikimedia.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="510" src="https://3.bp.blogspot.com/-UPTvyhG_jyw/WLGg27G9NJI/AAAAAAAAhFs/GqURvLKvKH0NXg_aTFtaANV3OrEVPN0zQCLcB/s640/eimac_tubes_wikimedia.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">(Wikimedia)</td></tr>
</tbody></table>
In my <a href="http://blog.aa6e.net/2017/02/sb-220-amp-need-new-tubes.html" target="_blank">recent post</a>, I reported some measurements on the power tubes (Eimac 3-500Zs) in my SB-220 amplifier to see if they still were serviceable after ~45 years. (Mostly, yes.) But this started me to wonder about the "Eimac" name, which, though once the gold standard, has largely disappeared in the Amateur Radio market.<br />
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With the help of <a href="https://duckduckgo.com/" target="_blank">DuckDuckGo</a>, I was able to trace a <a href="http://ethw.org/Eimac" target="_blank">long corporate history</a>, starting with the original Eitel-McCullough company (1934), which became Eimac. Then, a merger with <a href="https://en.wikipedia.org/wiki/Varian_Associates" target="_blank">Varian Associates</a>, ending up as a part of <a href="http://www.cpii.com/" target="_blank">Communications and Power Industries (CPI)</a>.<br />
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The good news is that, within CPI, the Eimac name still exists, and they still market power transmitting tubes. Alas, the classic glass envelope / internal anode tubes (as shown above), including the 3-500Z, are no longer offered by Eimac. (Some are still widely available as imports and marketed by firms such as <a href="http://www.rfparts.com/" target="_blank">RF Parts</a>.)<br />
<br />
Eimac is found in high-end markets for commercial, industrial, and military transmitters. Glass has given way to ceramic for insulating seals, while external directly cooled anodes are the choice for efficiency and performance. "Low end" Eimac tubes (triodes and tetrodes that are effective for our 1.5 kW power levels) may still be produced in low volumes, but they will be very expensive compared with glass envelope imports for our <a href="http://www.ab4oj.com/quadra/icas.html" target="_blank">ICAS</a> operations.<br />
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Over recent years, the old vacuum tube technology has been replaced by solid state designs, especially for commercial service. So there is little demand for the kW size tubes. Still, it's much cheaper to keep an SB-220 going with new imported tubes if needed, than to upgrade to the latest transistor amps.<br />
<h3>
<b>Your reward for reading this far!</b></h3>
CPI provides a <a href="http://www.cpii.com/library.cfm/9" target="_blank">library</a> of some of the older Eimac applications support documents. I found "Care and Feeding of Power Grid Tubes" especially interesting. So here are some links to the PDF files. The basics will be interesting to ham operators, especially those of a certain age. The advanced sections cover some fascinating large and exotic transmitting tubes that most of us will never see.<br />
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<div>
<a href="http://www.cpii.com/docs/related/22/C&F1Web.pdf" target="_blank">Care and Feeding of Power Grid Tubes: Introduction</a></div>
<div>
<a href="http://www.cpii.com/docs/related/22/C&F2Web.pdf" target="_blank">Care and Feeding of Power Grid Tubes: Section 1 & 2 - "What is a Power Grid Tube?"</a></div>
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<a href="http://www.cpii.com/docs/related/22/C&F3Web.pdf" target="_blank">Care and Feeding of Power Grid Tubes: Section 3 - "Electrical Design Considerations"</a></div>
<div>
<a href="http://www.cpii.com/docs/related/22/C&F4Web.pdf" target="_blank">Care and Feeding of Power Grid Tubes: Section 4 - "Linear Amplifier and Single Sideband Service"</a></div>
<div>
<a href="http://www.cpii.com/docs/related/22/C&F5Web.pdf" target="_blank">Care and Feeding of Power Grid Tubes: Section 5 - "Neutralization"</a></div>
<div>
<a href="http://www.cpii.com/docs/related/22/C&F6Web.pdf" target="_blank">Care and Feeding of Power Grid Tubes: Section 6 - "Operating Conditions for Various Applications"</a></div>
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<a href="http://www.cpii.com/docs/related/22/AB21.pdf" target="_blank">Conditioning of Large Radio Frequency Power Tubes </a></div>
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<a href="http://www.cpii.com/docs/related/22/AB18.pdf" target="_blank">Extending Transmitter Tube Life</a></div>
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<a href="http://www.cpii.com/docs/related/22/AB20%20-%20Measuring%20Temp%20of%20PG%20Tubes.pdf" target="_blank">Measuring Temperatures of Power Grid Tubes #AB20</a></div>
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Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-68098092062683337282017-02-14T23:53:00.005-05:002017-03-13T11:27:09.843-04:00SB-220 Amp, need new tubes?<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-7VLx1Hnyck4/WKPWbezwnKI/AAAAAAAAhAs/r-qDzm5kvbIvND99PufktE1S1q4NWeHHwCLcB/s1600/HiPowerTube3-500_C.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="200" src="https://4.bp.blogspot.com/-7VLx1Hnyck4/WKPWbezwnKI/AAAAAAAAhAs/r-qDzm5kvbIvND99PufktE1S1q4NWeHHwCLcB/s200/HiPowerTube3-500_C.jpg" width="117" /></a></div>
My station has a trusty <a href="http://www.rigpix.com/linears/sb220.htm" target="_blank">Heathkit SB-220 amplifier</a> for those times when 100W is not quite enough. I don't use it a lot, but I am considering whether it's time to get a new pair of 3-500Z tubes.<br />
<br />
The amp was built by Paul Gallier (WQ1C, now SK) in 1972. Paul upgraded the amplifier with many of the recommended mods, including new power caps, QSK switching, bias cutoff, etc. But so far as I know, I still have the original <a href="https://en.wikipedia.org/wiki/Eimac" target="_blank">Eimac </a>3-500Z tubes.<br />
<br />
The amplifier seems to work well, except that it's hard to get full power output on the 10 and 15 M bands. I had data from WQ1C that suggested that he was getting fairly constant power output across 80 through 10 M at the time I bought the amp, some 10 years ago.<br />
<br />
Time to make some measurements of my own. Since there are a number of settings that can be twiddled, it is hard to know exactly how to make a comparison. You can adjust drive level (Flex 6500 output), amp tuning and loading. I settled on CW mode, with the amp switched to its low voltage "CW/Tune" setting. I looked for maximum output power (Po) with various drive and loading settings, at the maximum allowed grid current (Ig) of 200 mA. Po is measured with an <a href="http://www.telepostinc.com/lp100.html" target="_blank">LP-100 RF Wattmeter</a> feeding a Drake DL1000 dummy load.<br />
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<a href="https://2.bp.blogspot.com/-3-HtQ22V02c/WKPYQKlComI/AAAAAAAAhA4/5NZKiely4V04j1lKxcyAPH19SxcKTLfhwCLcB/s1600/sb220-1.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="223" src="https://2.bp.blogspot.com/-3-HtQ22V02c/WKPYQKlComI/AAAAAAAAhA4/5NZKiely4V04j1lKxcyAPH19SxcKTLfhwCLcB/s400/sb220-1.png" width="400" /></a></div>
The results are shown in the figure. I plot the DC input power (Pdc = Ip x Ep), output power (Po) and efficiency (Po/Pdc). Clearly, there is a problem with 10 and 15 M, which show low output power and efficiency. At 10 M, the output power has fallen by 3.3 dB -- about 1/2 S-unit.<br />
<br />
High frequency fall-off like this is said to be a typical problem in power tubes as they age. (See <a href="http://w8ji.com/Amplifiers.htm" target="_blank">W8JI's amplifier site</a> for example.) Presumably the gas ions, being much heavier than electrons, move relatively slowly and "gum things up" with their long transit times at higher frequencies. (I would like to find a more technical treatment of the problem.)<br />
<br />
It's good to have data. Now the question is whether getting back that 1/2 S unit on one band is worth the cost of new tubes. Short of that, there is the possibility of reducing gas by "<a href="https://en.wikipedia.org/wiki/Getter" target="_blank">gettering</a>" the tube -- running with high dissipation (plates glowing red!) -- which activates a special gas-absorbing getter material covering the plates.<br />
<br />
<b>Note added:</b> Running with bright glowing anodes is dramatic, but I have to wonder if it is safe for the SB-220. The cooling "system" (fan) is rather primitive. It seems to be OK for normal ICAS operations (plates dim if red at all), but when dissipating power at the maximum spec. (500 W) for any length of time, you have to worry. I understand that a particular issue is cooling of the anode and base connection pins, where a sustained overheating will compromise the glass seal, letting the vacuum out. So aggressive gettering is probably not a good idea with the stock Heathkit. It would be handy if we had a way to measure those critical seal temperatures.Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-75382473013231248572017-01-15T11:19:00.000-05:002017-01-15T11:45:45.514-05:00First Meteor Scatter Contact<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-93CfXhoYmvw/WHudCR9y1zI/AAAAAAAAg8A/Em_vjryybOIx_QNZoda0z5whkSMEmhiHgCLcB/s1600/Perseid_meteor_shower.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="213" src="https://1.bp.blogspot.com/-93CfXhoYmvw/WHudCR9y1zI/AAAAAAAAg8A/Em_vjryybOIx_QNZoda0z5whkSMEmhiHgCLcB/s320/Perseid_meteor_shower.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Meteor in a Perseids shower, Wikipedia</td></tr>
</tbody></table>
It's not exactly ground-breaking in the Amateur Radio world, but I'm pleased to have made my first "meteor scatter" contact with another radio amateur. Thanks to W4IMD, Peter in Georgia, who exchanged information with me over a path of about 1,100 miles on 50.28 MHz with about 50 Watts of power. We used the software mode called "<a href="https://docs.google.com/viewer?url=http%3A%2F%2Fphysics.princeton.edu%2Fpulsar%2FK1JT%2FK1JT_EME_2016_Venice.pdf" target="_blank">MSK144</a>", developed by friend and colleague Joe Taylor (K1JT).<br />
<br />
Meteors strike the Earth's atmosphere frequently, even in the absence of a big meteor "shower". They generate a trail of ionization that lasts up to a minute or so (at 50 MHz), which is sufficient to exchange a bit of information between ground stations that have mutual visibility -- up to about 1,300 miles.<br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-eR3wJq8L-2A/WHul109q6wI/AAAAAAAAg8M/W1Yq6ZN_PiQGWcZSY9JNj0C2QEP0laLPACLcB/s1600/msk144_flex.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://2.bp.blogspot.com/-eR3wJq8L-2A/WHul109q6wI/AAAAAAAAg8M/W1Yq6ZN_PiQGWcZSY9JNj0C2QEP0laLPACLcB/s1600/msk144_flex.png" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Strong meteor burst from N0TB in Minnesota displayed<br />
on FlexRadio FLEX-6500 SDR transceiver</td></tr>
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There are other worlds to conquer: working through Amateur Radio satellites or the ultimate in weak signals -- moon-bounce communication. All these have been done one way or another for decades, but they keep me learning new tricks!Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0tag:blogger.com,1999:blog-11282959.post-57381162583144689052016-12-26T10:46:00.001-05:002016-12-26T10:50:16.546-05:00A network benchmark updatePreviously, I've posted several Comcast / Xfinity's benchmarks for our CATV Internet service. (Click on "Benchmark" topic at right.)<br />
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Lately, the IPv6 service seems pretty reliable with my system. That <a href="http://blog.aa6e.net/2016/06/ipv6-things-that-fix-themselves.html" target="_blank">was a problem</a> for some time. It may have been a bad interaction between the Comcast plant and my local routers, but it just went away. It may have been a Comcast reconfiguration that helped us, but it also could have been an Asus firmware update. I am now running <a href="http://asuswrt.lostrealm.ca/" target="_blank">ASUSWRT-MERLIN firmware</a> on the Asus RT-N66U router, which I can highly recommend as an expanded and improved version of the Asus distribution.(It cured a long-standing issue with JFFS2 overflow.)<br />
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Again, I highlight the <a href="https://www.dslreports.com/speedtest" target="_blank">DSL Reports speed test</a>, which checks your "real world" network performance, including the dread "buffer bloat". Today is Boxing Day (Dec. 26), and DSL-Reports is giving me a so-so report and a good report. Here they are, separated by half an hour:<br />
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<span id="goog_301079264"></span><span id="goog_301079265"></span>The variability may be partly due to the speed test's different selection of test hosts. But it may be something real about Comcast or the Internet "weather". These tests use IPv6, it appears.<br />
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For comparison, between these two tests, <a href="http://speedtest.xfinity.com/" target="_blank">Comcast's own speed test</a> shows this:<br />
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This is the available speed within the Comcast network, which seems to be the best possible result -- not fully representative of what you experience with a random Internet connection -- even if the server is fast and well-connected. (Note that the driving distance from Branford CT to Boston is really about 144 miles, not under 50. Go figure.)Martin AA6Ehttp://www.blogger.com/profile/14329680325036851280noreply@blogger.com0