no tv signal - apparently

[JohnyMedia]

I have been getting more and more problems with the tv signal - apparently. Started with programs breaking up then halting altogether, say 20-30 mins into a recording. Also, time remaining getting very confused (like showing 16 hours or something). Then, a reluctance to even tune to certain channels. In the end, I phoned freeview who said that work was being carried out on the crystal palace transmitter - you may remember my previous post a few weeks back.

Anyway, the situation is now that I get no tv signal, and BDA scanner confirms this - it simpy says "nothing found" for all frequencies.

So, I went fault finding today, fully expecting this to be a hard ware fault ie aerial, distro amp etc. But I hooked the laptop up with its usb tuner, and low and behold it found everything with 100% signal and 100% quality (save on an upper frequency band mux, that I don't think I'm using, just copies of the same channels). So now I am puzzled. Presumably a software fault with drivers or something, in the media centre (runs xbmc with two Avermedia tuners).

I'm guessing that originally, there was some trouble due to the Crystal Palace works, but now it must have morphed into an entirely different fault?

If anyone can suggest what to try next, that would be great!

PS: Win XP, and device manager reports that both devices (tv cards) are working properly.

Hmmm... I just gave up for today, plugged everything back in and I got bbc1 so tried a bda scan, it stops to look at certain frequencies, but sais "scan timed out" so I'm guessing the signal is there but bad? Maybe the usb tuner on the laptop is just loads better?

[johnsonx42]

try the usb tuner on the HTPC, using the same cable connection as the avermedia tuner.

post logs of your scan.

[jcjefferies]

You mention the words "Windows XP" and "Both TV cards" so the obvious question is have you installed the "dvbfix" as XP has problems using more than one TV tuner. However when I used XP on my server with dvbfix it would make two recordings ok but only did a partial scan for channels. So I would remove dvbfix to do a scan and add it for normal use so gave up after a while and installed Vista!

Chris

[JohnyMedia]

Thanks for the replies. Yes I did install dvbfix a while back, I think when I was first getting some eratic recordings, though everything had been ok before that. I have not had to try rescanning since, and was hoping to avoid it - at least for the foreseable.
I'll investigate further tomorrow - I was sure it was hardware, then not so sure (hence my post) , now I'm leaning towards hardware again - I'll open up the distro amp (its running the tv fine btw) and see if there's any dry joints etc.
I'm afraid my system is far from ideal - I'm in a dip in North West London, and its down on the map as a bit of a freeview blackspot anyway. I put an aerial up on the chimney stack a few years ago - a good high gain anti ghosting dvb one. That feeds into a very high gain booster (maybe 24db?) in the attic, which sends the signal to several places - even down the garden The branch that goes to the living room has another active distro/booster (only 6db I think so not much) to feed the tv / pc tuner 1 / pc tuner 2.
So, when I get trouble like this - and the pc-tv has been a constant problem, though usually due to software issues - I have a lot of scope to find the solution.
I'll try the usb stick in the media centre - if it doesn't look like its going to screw something up adding that just for a test.
I've got an oscilloscope too - might hook that up and see if it sheds any light, but I felt the DBA signal thing was doing the job.

[Lao Pan]

I'm afraid my system is far from ideal - I'm in a dip in North West London, and its down on the map as a bit of a freeview blackspot anyway. I put an aerial up on the chimney stack a few years ago - a good high gain anti ghosting dvb one. That feeds into a very high gain booster (maybe 24db?) in the attic, which sends the signal to several places - even down the garden The branch that goes to the living room has another active distro/booster (only 6db I think so not much) to feed the tv / pc tuner 1 / pc tuner 2.

I've got an oscilloscope too - might hook that up and see if it sheds any light, but I felt the DBA signal thing was doing the job.

One thing that perhaps you should investigate is 4G 800MHz interference - there is more chance that it will effect you if you have a booster.

From the at800.tv website

The highest frequency at which Freeview signals are transmitted from Crystal Palace is 540 MHz, while the new 4G at 800 MHz signals begin at 791 MHz. In addition, the high signal strength from Crystal Palace makes aerial amplifiers less likely to be needed. Amplifiers can cause problems by boosting 4G at 800 MHz and causing signal overload in television equipment. In Brighton, Freeview is carried on frequencies up to 790 MHz.

Having said that - I have been having similar problems for the last week and am wondering if the new HD mux on an adjacent transmitter (Wenvoe) is causing interference.

[JohnyMedia]

Yeh... when I first had trouble a few weeks back, I contacted the 800 people as well as freeview, that 800 people were not that helpful - I was hoping to get some free filters to try.

Today, I hooked up the laptop again, but got inconsistent results - ie yesterday it picked everything up, today only some channels. That is, NextPVR tuner only found some stations, but the BDA Scanner found everything ok. Could be the 800 thing (as I think it will vary depending on weather and time of day) or could be anything else such as water in the aerial cable, dodgy leads, boosters etc. If only it was analogue - you can see straight away what's up, ie grainy=low signal etc...
I opened up the distribution amp near the equipment, no dry joints or anything.
Ive been experiencing breakup on my DAB tuner recently, too...
Anyway, just been onto at800 and they are sending someone out on Monday - they should be able to advise me what is at fault, and supply a filter if necessary. At least then if the aerial is ok I can focus on software issues.
thanks for all the help thus far

[jcjefferies]

It sounds as if you may have several problems however when I had dvbfix installed it would scan the first mux and occasionally the second then stop.

Chris

[JohnyMedia]

The BDA Scanner scans everything still. The Nextpvr seemed to as well, (when tyrying on my laptop running Vista) but a lot of the stations within muxes were there but greyed out instead of strong black type.
Hopefully on Monday, I can at least establish if the aerial sytem is ok and if interference is playing a part in it.
I think you might be right though... could be more than one issue

[bgowland]

I smell a rat...

A couple of weeks ago I noticed all my recordings were failing - I didn't spot it straight away as mostly they were just re-runs I'd seen 10x over. The feed to my npvr box is from a loft aerial via a powered splitter / amplifier to my 4x DVB-T cards.

Originally I suspected the splitter so put the aerial connector into each capture card in turn and scanned - absolutely nothing showed so I suspected the loft aerial but it's a PITA to get up there and hadn't got around to it. A couple of days ago I tried a powered set-top type aerial (which has worked for me before) and still got nothing.

Having just spotted this thread I plugged the loft aerial directly into one card, scanned and got every channel on every MUX. OK, suspecting it might be the 4G issue, I plugged the aerial into the splitter / amplifier and still got all channels. Huh? Can't help feeling somebody somewhere has been screwing with something.

Cheers,
Brian

[martint123]

[QUOTE=JohnyMedia;468644 but a lot of the stations within muxes were there but greyed out instead of strong black type.([/QUOTE]

Greyed out only means that they already have been scanned and exist in the database. Black means new or moved I think.