Unreliable Freeview... have I located the problem?

[Steve]

Now most of you will shout at me "YES", but I just want to be sure.

I've built a media center PC and have some trouble with the DVB-T signal. Here's the lowdown:

Compro U3 USB tuner works OK, stutterring maybe once every 15 minutes, barely noticeable.
Terratec Hybrid USB stutters frequently, more noticeable on certain channels.
Compro T200 PCI tuner stutters a lot, seems worst on the ITV/C4 mux.

The ITV/C4 mux [C55 (746MHz)] is the weakest in my area, so I'm thinking signal strength. The funny thing is the standalone Freeview box has no issues, but I guess maybe it's just more robust?

And now for the clincher: The aerial is pointing in the right direction, but about 30º above horizontal. It's not a special high gain aerial or anything, by the looks, but it must be able to receive wideband seeing as we get Freeview.

In the attic there's a triple output signal booster, so my guess is that's what has enabled us to get a signal despite the dodgy aerial alignment.

So, before I get somebody to sort out the aerial, I just want to make sure I've not missed something silly!

I'm using Nvidia PureVideo decoder on MCE2005.

Thanks guys, as always

[Steve]

Nobody?

[BigBry]

It may be worth checking the signal strength via the software that comes with each card. For example the Compro DTV software shows you a signal strength for each channel you tune to. There are other methods for doing this but it varies in reliability. This will give you an idea if it's the signal quality/strength.

Stuttering in MCE can be many other things but check your signal first.

[Steve]

Signal strength on some of the more reliable channels is ~100%, while others on the lower power multiplexes is 60-70%.

I replaced one of the 2 metre coaxial cables connecting to the tuners and this helped. Seems they're quite susceptible to interference. Unfortunately there's no a lot I can do about the aerial wiring in the house as it's rented.

Reckon getting the wonky aerial fixed will improve the SNR enough that other interference will be less of an issue?

[BigBry]

Well it's certainly not going to hurt. 60% is a bit on the low side so the aerial alignment may be enough. However as I mentioned before there are plenty of other things that could be causing the stuttering, for example;

• With Purevideo set the pulldown menu on the first screen from 'smart' to 'automatic'. (Sorry I can't remember what the exact heading is).
  
• You can also have the 50/60 hz issue with certain displays that causes jerkiness.
  
• I recently had an issue with a Core 2 Duo getting messed about by a motherboard CPU load program (i-cool from Gigabyte). This caused stuttering in anything TV or DVD related.

[Steve]

The stuttering is definitely related only to the television feed. It's the same with different codecs, not just PureVideo. DVDs are fine.

I don't have any programs messing up the system load.

Thanks for your help.

[Clingy]

Not sure whether my experiences are relevant but I am having a nightmare with my Freeview so have done quite a bit of research. My unboosted signal strength is around 70%. We are in a poor signal strength area and I have just installed a Ultra high gain aerial. With a non masthead booster I am getting 85% signal but still wth loads of problems on my two DVB-T devices.

It would appear that interference can play a big part in Freeview and this interference can come from one of many sources. My list of things to try include:

1) Recabling with digital/satelite quality cable (CT100?). At the same time re-routing cable to avoid running alongside mains cable.
2) Fitting a TVI Filter.
3) 5% elevation of my aerial.
4) Purchasing a better quality Freeview box.
5) Fitting a low noise masthead amp.

Amplifiers in themselves are non always a good thing. They amplify noise and interference as well. This is particularly the case with the plug in types.

Some sites I found useful are

here

and also this one to determine best signal

Wolfbane

[Bluecube]

I've got a Freeview box that plays back TV with no problems on a 50% signal. However, it does also say that the signal quality is 70% so there's two different factors there.

One thing I don't quite get is how your Freeview box can pick up and play channels with no problem but your PC linked tuners can't. I was about to say just what BigBry said but you've got them covered. Bit of a puzzler there. Maybe a memory issue?

[Steve]

We got a new aerial installed yesterday. Now one of the tuners on which TV was dodgy works near flawlessly when I'm not faffing about with the wiring

Trouble is the tuner that DID work is now b0rked. It'll sometimes work, then break until I unplug it from the USB and plug it back in. A channel scan also seems to break after a short while on it. The third tuner will detect some muxes, then not others, or visa-versa if I play with the adjustable attenuator I have.

Now I'm just confused

[Trippledence]

My freeview tuner jumps like hell if I use a substandard cable with it, what with all the wires hanging arond the back of my PC, use a shilded on and its fine, again I found the USB Leadtek tuner to be more sensitive, also juttering seems to be caused by the whole vidio overlay things, if you agrivate it somehow.

[autopilot]

We got a new Digital Arial fitted to our roof today, and i learned a few things and digital TV of the guy i did not know...

It's not about the signal strengh much now, most areas are covered now - analogue ariels just can't get certian frequency bands at all. We had about 90% of channels perfectly and the other 10% not at all. We now have them all.

Secondly, digital TV signal strengh becomes far more weaker the more you split it off to different devices than i thought. About 10db per device, much more than analouge. So try having just one device plugged in and test that before adding others.

[BCFCRULE69]

try a booster it worked for me

[Sinizter]

The Nova-T PCI I had in my PC worked OK, missing some channels and stuttering and blocking on others.

The Compro T200 card does not work.

Finally got myself a freeview box and that works, with occasional stuttering and blocking of channels.

All this is due to me having to use a boosted indoor antenna as I dont have an aerial in my uni accomodation.

The cards tested on my system all work flawlessly without any problems when installed on other systems and connected to a rooftop aerial using a wall socket.

[Rack]

I've asked this on AVForums, and everyone on there said that DVB-T Cards have poorer performance than Freeview boxes when it comes to signal strength. I have the same issue, and bought a booster from Argos for £4 today. They also told me the boosters are typically the same, so don't blast a c-note on them.

Autopilot, I thought that digital signal is still modulated in the UHF frequency band like the analogue signals are. 'Digital' antennas sounds like someone cashing in on the change over from analog, except that they could be higher gain (more dipoles) for fringe areas...