Cable to U-Verse and back again

Executive summary: AT&T U-Verse out, Comcast cable in.

I've been living as an Amateur Radio operator with AT&T's U-Verse service for about 18 months.  It was a great experiment, to see whether ham HF operation could be compatible with U-Verse's VDSL2 signalling.

VDSL2 delivers a bit stream over channels stretching from a low frequency to over 8 MHz, so it was a challenge to work at power levels over 50 W or so in the 160, 80, or 40 M bands.  We tried lots of things -- ferrites everywhere, shielding, etc.  At the same time, AT&T's technology improved, with higher bit rates and more tolerant modems.  We weren't too unhappy as U-Verse customers -- but that was only because I don't spend a lot of time on the air (especially QRO) during TV viewing hours.

Still, I have grown tired of having to think too much about my TV, Internet and phone service.  They should just work!  Even for radio amateurs.  Back to the cable world -- Comcast.

The problems with Comcast will undoubtedly come.  Maybe they'll throttle me if I don't watch enough NBC shows. But in 2 years, maybe we'll see Google or Verizon or somebody offering something more attractive?  Stand by.

U-verse Downs & Ups

Image via WikipediaThe AT&T U-verse saga continues.  I was sad to find that, after my initial tests that showed I could run 80 M CW at 800 W, my latest round of tests showed really bad sensitivity.  I couldn't run over 20 or 30 W without causing the U-verse Residential Gateway (RG) to lose sync.  (That can mean a 1- or 2-minute TV and phone outage.)

After a bit of probing, it became clear that the RFI was entering on the internal home phone wiring.  Disconnecting it from the RG quieted the problem, but alas we are now very dependent on the U-verse VOIP service.  Disconnection is not an option, normally.  (Cell coverage is poor here - a story for another day.)

The AT&T installer had not fully appreciated my phone entrance system, which uses a special DSL surge suppressor that is bolted onto my Single-Point Ground system.  He ran his CAT5 cable from the wall plate straight into the RG. (That's OK for RFI, but not great for lightning surges.)  The house phones were fed via a circuitous route passing (backwards!) through the surge supressor, and generally making a nice RF pickup loop.

This afternoon, I pulled out half my station (the heavy part!) so I could get access, and rewired the phone system, adding ferrite chokes, etc.  Result: no trouble now with 800 W at 3600 kHz.  I'll do more tests later, when the contest goes away.

U-verse RFI tip:  You can use the ubiquitous DSL telephone line filters as an RFI choke.  These are transparent to telephone audio, but block the DSL frequencies.  (It's not clear whether they are effective at up to ~8 MHz that VDSL = U-verse uses, but it seems likely they are.)

More complete info will be at http://aa6e.net/wiki/RF_Compatibility.

More U-verse work

I did some more testing on U-verse vs HF QRO operation today.  The main results are reported at http://aa6e.net/wiki/Uverse, which is going to be where the data from this work is accumulated.  We only give the late breaking news here.

As expected, winding the incoming DSL line on a ferrite core (8 turns, type 77) has helped a fair bit -- allowing a doubling of amplifier power on a good range of frequencies.  We also see that the U-verse DSL does not show any problems for QRO at 20 meters and up.  80 and 40 (and 160) are going the be the troublesome bands.

But we have more countermeasures we can try.  That will be for another day.

I also have trouble with my carbon monoxide detector going off.  (It's very loud!)  And pickup in my computer loudspeakers is annoying on 40 M.  All this will yield to filtering.

Uverse vs 80 meters

So, we've finally got to the point of some stability with Uverse in the house for TV, Internet, and telephone service.  That is, without doing much ham radio.

I discovered a nice tool, U-Verse Realtime, which lets you show many parameters of your Uverse operation. It's free software for Windows machines, and it seems to work in my virtual Windows XP machine.  (VMware under Ubuntu Linux.)

The first bit of science is to measure my "bitloading".  That shows what parts of the frequency spectrum are being used for the underlying DSL connection.  The results:

The chart shows that frequencies between about 100 kHz and 3.7 MHz are used for download (yellow), while 3.7 - 5.0 MHz are used for upload (green).  There is a small higher region, about 5.3 - 5.5 MHz also allocated to download.

The increasing line attenuation with frequency is apparent.  (At least, if you believe that "bitload" has something to do with signal power.  I don't really know that.)  The electrically measured line length from the Uverse node is 2554 feet, which puts me in the lowest of 3 service tiers.

OK, second science test.  The active DSL spectrum includes the 80 and 160 M ham bands.  What's the interference potential?  This is not a simple question.  The interference from Uverse's DSL connection might not be much of a problem.  Why?  The received signal is going to be weak (indicated line attenuation is 21.6 dB.) The locally stronger transmitted signal, 3.7 - 5.0 MHz, is mostly outside the 80 M band, although there could be problems between 3.7 and 4.0 MHz, in the SSB band.  Fortunately (?), the 80 M band is naturally so noisy that the interference might not be noticeable.

The thing to worry about, I think, is interference to Uverse service.  I ran a very short test at ~3536 kHz CW.  I was downloading a large file over the Internet and listening to an HDTV program in the other room.  Transmitting with ~90 W output caused no apparent problems.  Transmitting at ~850 W killed the DSL connection pretty quickly.  Download stopped, and the TV image froze. It took about 70 seconds to reacquire the signal after transmission stopped.  (At least nothing was destroyed!)

This is all very preliminary.  We will need to improve the wiring and experiment with ferrite chokes -- probably on the incoming DSL connection.  There is no guarantee that kilowatt 80/160 M operation will ever work, but it might...

Uverse - First Impressions

Image by doegox via Flickr
As noted in the prior post, we are switching to AT&T Uverse.  Formerly, we had Comcast cable for TV, AT&T DSL (6 Mb/s) for Internet, and plain old telephone service (POTS) from AT&T.  Now we get all 3 services from Uverse - the so-called triple play.  Voice is now VOIP carried over the underlying DSL technology.

The installation went very smoothly, and the technician was not too fazed by my 1 KW ham transmitter or my Linux-based household network. (Of course, he didn't guarantee how well things would work in an intense RF environment.)

It turns out our distance from the neighborhood node is 2,554 feet. (This is FTTN service - fiber to the node.) By phone, AT&T had quoted ~750 feet from their not-too-accurate database estimate.  The service limit is 3,500 feet, according to our tech.  Our airline distance may be 750 ft, but our lines don't go direct.  This matters, because the ultimate data rate declines with increasing cable length.  We have ended up in the bottom tier of service, sigh.  This limits the number of TV channels that can be recorded or viewed simultaneously.  That's probably OK for us, but Internet service will be capped at 12 Mb/s for the foreseeable future.  Having double our previous speed is good, but eventually 12 Mb/s may feel too slow.  (Meanwhile, Comcast is saying 100 Mb/s service is coming.  No mention of cost.)

Preliminary observations: Everything works.  That's very good - much better than our early struggle with DSL.  We get a real 11+ Mb/s of data download.  TV works, but somehow the order was bungled and we do not have HD service yet.  A little worrying, the picture on SD TV is rather softer than we had with Comcast.  That probably reflects excessive compression by AT&T.  I wonder how much better HD will be.

Phone service by VOIP works nominally, but now we rely on a UPS to keep service up in a power failure.  POTS emergency service was much superior!
The level of system integration and the TV user interface is much better than what we had before.  Of course, Comcast also offers the triple play, but their HD video recorder system (and its control options) was inferior.  AT&T's services available through the TV are very interesting - receiving your phone voicemail?  I haven't tried that yet.

The industry has still not solved the command and control problem for home entertainment systems.  Even with the new system, we are in remote control hell if we ever want to use our DVD or other add-ons.  This is particularly frustrating for the less technical members of the household!  Why this could not have been resolved by now with some kind of standardized control bus among "home theatre" devices is not clear to me.  No one seems to take this major consumer interest very seriously.

Stand by for occasional further reports.

Update:  A few worrisome but non-fatal issues emerging.  Uverse VOIP service gives too many "fast busy" signals when calling some "well known" local numbers -- and even when calling Uverse support!  You would think "the phone company" would understand phone technology, even if it's VOIP.  This is a problem that almost never happened with the POTS network.

On the TV side, accessing some Uverse help files (apparently a TCP/IP web transaction?) return a 404 Page Not Found screen, which should never happen.  A while later, the request worked correctly.

It Begins Again... (AT&T)

I've been enjoying stable "Elite" DSL service (6 Mb/s download) for about 5 years now.  Time to update to AT&T's "Uverse" service?  It just arrived in my neighborhood.


Image via WikipediaMy initial DSL service was a pretty grim story. SBC took over the Connecticut territory from SNET not long before.  (SNET, of blessed memory, was a member of the original Bell network, having been Connecticut's own phone company for a very long time.  Sigh!)


Surely, AT&T would have figured out their new Uverse TV/Internet/Voice technology by now. Nothing can go wrong, go wrong, go wrong.

Actually, they've made 3 errors so far just scheduling the installation, and I've had to talk to 4 or 5 people on the phone.

The interesting technical issue is that their internal database shows that I am supposed to be 733 feet from the "node" (VRAD) in my neighborhood.  But, tracking real phone cables, I come up with some long zigs and zags that may add up to triple that number.  So there's a chance the tech will show up (at the newly appointed hour, we hope) and declare that my connection would be substandard.  And the whole thing is off.

I'm not canceling my Comcast TV just yet.