Tag Archives: dvb-t

usb tv tuner problems (dvb-t) part 4: narrowing down the problem.

Computer Aid Posted on by

I run both intel mobos side-by-side, (running pclinuxos and mepis), and I get no fault after 12 hours…

OK, lets try windows… the customers PC (after the repair install) works flawlessly

Mine: it still locks up, but less frequently than the first time (could the jumper that enabled the sound have had any effect?).

At this stage, I wonder what could be causing the lockups… I suspect everything… AGP video card (geforce 6200)… but the onboard video card also causes lockups.

After a lot of testing, I find I can record ABC (the worst station, with reception of 5 out of 6 bars) for over 8 hours without a problem (overnight), but as soon as I start using the PC, it can lockup within a few minutes.

I install a great tool called process master, so it will automatically increase the priority of the totalmedia process (and virtually eliminate any jerky TV playback… even using HDTV).

I still don’t like that the TV tuner gets very warm, but it seems to keep working despite the heat.

I also notice I get zapped if I unplug the TV tuner from the usb port, and touch the antenna shield, and the PC case. I whip out my volt meter, and I see the shield has about 110V AC, and about 90V DC :-()

But a bit of research shows that this can be normal if the antenna is plugged into something else (like a TV or VCR).

After a few more weeks of careful observation, I start to see a pattern:

The PC is much more likely to lock up if I happen to be moving the mouse pointer at the same time as recording (or watching) TV… the mouse is a USB mouse… the TV tuner is also USB…

I get the feeling USB is just not as reliable as I would have thought… particularly at high data rates.

I also notice the chance of a lockup are much much higher if I’m recording/watching HDTV.

So what I’ve done is plug the mouse (trackball actually), into one of those usb to din adapters, so that the trackball uses the din plug instead of the usb.

After that, the only lockups every day or so… but much more frequently if I’m watching HDTV. I still reckon there is a problem with the mobo, but it could even be a design flaw, so taking it back to BXXXXXXX] would be useless.

I keep wondering if a PCI TV tuner would have been a better option…

Anyway, the moral of the story is:

If you are going to get a TV tuner, make sure:

  1. You have a fast, modern PC.
  2. you have excellent antenna reception.
  3. the software for the tuner has a reputation for good quality (it should work without changing process priorities manually)

usb tv tuner problems (dvb-t) part 1: you need a good antenna

Computer Aid Posted on by

After my VCR died a few months back, I decided to go “digital”, and I purchased a swann dvb-t (SW112-DVB) usb tuner for my main PC.

Once I plugged it in (and installed the totalmedia software), I noticed a few problems:

  • the picture/sound would sometimes stutter and jerk… sometimes it would pause for a second or two. It wasn’t too bad. I would often get a few minutes of continuous, uninterrupted TV
  • My PC would occasionally freeze, so that I would need to give it a hard-reset.

After a lot of research, I discovered a few things:

  1. If a digital tuner has poor antenna signal quality, then the image/sound don’t develop “snow” like the analogue equivalent. What happens instead, is you get the stuttering and jerking I mentioned above.
  2. If the PC isn’t powerful enough, then it could freeze while trying to handle the huge amount of data arriving via a usb port (or the picture could stutter and freeze).
  3. What you do on the PC (even just scrolling within a browser), can affect the TV.

Since the tuner was connected to my fastest PC (a sempron 2800+ with 1.5Gb of 400Mhz RAM), then it should work fine (assuming there is no AMD/mobo compatibility issue).

I also tried it on a 800Mhz PIII with a fast video card, but the PIII struggled to maintain 1 second of continuous TV.

I then tried a 1.5Ghz celeron M laptop. It did better than the PIII, but still struggled, with many stutters per minute.

I was thinking the DVB-T tuner might be faulty, but I wanted to eliminate the signal quality as a cause (since the normal TV was quite snowy).

While waiting for the antenna guy, I noticed that the DVB-T tuner got quite warm when it was operating. Could it be overheating? I took the cover off, and was contemplating a cooling fan for the warm chip.

I eventually got the someone from MrAntenna to take a look, and he fixed a few things (replaced an analogue splitter with a digital one (to me, both splitters looked identical), and put a better quality antenna cable to the PC.

After that, the stuttering stopped, but the PC lockups started happening every few minutes…

The antenna guy recommends sending the TV turner back under warranty.

I decide to try it on one more PC: I take my workshop test PC (P4 1.7Ghz), and carry it upstairs to the “office”. And it works flawlessly over a 10 hour TV recording.

to be continued…