[solved] Cannot find TV DVB-T2 channels (TBS-6281SE) (2 Viewers)

[SimonP]

Thanks for getting back to me so quickly, I'm out of my depth here so I appreciate the help.

1) That's what I thought.

2 & 3) According to Wikipedia, T2 currently operates at 586.000MHz, I did another scan of Mendip and the entry saying '3p - freq:586.000/167:8' comes back with '3p - 586167 8:Nothing found'. Signal level is a bit lower than the others but still about 75% (Mendip transmitting station - Wikipedia)

4) I've done that, the relevant entry looks to be:

[2023-10-27 09:55:51,298] [Log ] [10 ] [INFO ] - dvbt: ScanVBT:tv: Freq:586000 ONID:-1 TSID:-1 SID:-1 PMT:0xFFFFFFFF FTA:False LCN:10000 BandWidth:8
[2023-10-27 09:55:51,298] [Log ] [10 ] [INFO ] - dvbubmiting tunerequest Channel: subChannel:0
[2023-10-27 09:55:51,298] [Log ] [10 ] [INFO ] - dvb:using existing subchannel:0
[2023-10-27 09:55:51,299] [Log ] [10 ] [INFO ] - dvbubmit tunerequest size:1 new:0
[2023-10-27 09:55:51,299] [Log ] [10 ] [INFO ] - subch:0 OnBeforeTune
[2023-10-27 09:55:51,299] [Log ] [10 ] [INFO ] - dvbubmit tunerequest calling put_TuneRequest
[2023-10-27 09:55:52,962] [Log ] [10 ] [INFO ] - dvbubmit tunerequest done calling put_TuneRequest
[2023-10-27 09:55:52,962] [Log ] [10 ] [INFO ] - subch:0 OnAfterTune
[2023-10-27 09:55:52,963] [Log ] [10 ] [INFO ] - RunGraph
[2023-10-27 09:55:52,963] [Log ] [10 ] [INFO ] - dvb: LockInOnSignal ok
[2023-10-27 09:55:52,963] [Log ] [10 ] [INFO ] - subch:0 OnGraphStart
[2023-10-27 09:55:52,963] [Log ] [10 ] [INFO ] - subch:0 Graph already running - WaitForPMT
[2023-10-27 09:55:52,964] [Log ] [10 ] [INFO ] - subch:0 SetupPmtGrabberid FFFFFFFF sid:FFFFFFFF
[2023-10-27 09:55:52,964] [Log ] [10 ] [INFO ] - subch:0 SetupPmtGrabberid FFFFFFFF sid:FFFFFFFF
[2023-10-27 09:55:52,964] [Log ] [10 ] [INFO ] - dvbt: tune: Graph running. Returning TvLibrary.Implementations.DVB.TvDvbChannel
[2023-10-27 09:55:53,000] [Log ] [10 ] [INFO ] - Scan: tuner locked:True signal:75 quality:0
[2023-10-27 09:56:13,025] [Log ] [10 ] [INFO ] - Scan Got 0 from 0 channels

5) I tried adding 3 to each of the settings under General/Scan but it was the same.

6 & 7) The TV signal strength is high, we're on top of a hill and can almost see the transmitter so no problem there.

8) I tried deleting the channels as suggested above (Mark top then bottom entries, right click and select delete) but it didn't help. I don't have anything special set up so I could uninstall and reinstall if you think it might help.

 

[CyberSimian]

[2023-10-27 09:55:53,000] [Log ] [10 ] [INFO ] - Scan: tuner locked:True signal:75 quality:0

This line from the log file shows that TV Server detected something at that frequency (signal strength=75), but was unable to extract anything meaningful from it (quality=0).

A signal strength of 75 does not seem unreasonable to me. However, I have just checked my HTPC receiving "BBC2 HD", and MP shows strength=98 and quality=69 using a TBS 6284 tuner card. My Sony TV shows strength=97 and quality=100 (but measures of strength and quality between different manufacturers products are not directly comparable). For DVB-T MUXes, I have on occasion seen lower values for strength using the TBS tuner (50-60), whilst still receiving a watchable picture in MP.

I am sorry, but I do not have an explanation for your problem. My guess is that it is related to the maintenance that the Mendip transmitter is undergoing at the moment. If true, your system should return to normal in a few days. If the problem persists... well, I don't know. It is possible that your tuner card has developed a fault in the DVB-T2 circuitry, but the only way to check that would be to replace it (and the replacement might suffer the same problem if it is a signal problem and not a tuner problem).

I don't think that re-installing MP would help. And since it seems to be a signal or tuner problem of some sort, I don't think that trying other software would help.

-- from CyberSimian in the UK

 

[SimonP]

I had the card and MP working in another computer some time ago and the HD channels were working but I didn't use it much, then I set it up again a couple of weeks ago in a different computer and noticed that there were no HD channels. Hopefully it is just transmitter maintenance but I'll check the connections, try a re-install, another PCIe slot and computer just to be sure. Thanks for your thoughts on this, I appreciate it.

 

[SimonP]

Now that IS weird. I tried everything, it was the same every time, until I left the outgoing cable off (it isn't plugged into anything at the other end) and the HD channels appeared! I can only assume the slightly low signal along with the open cable was enough to confuse it and kill them. Oh well, another lesson learned. Thanks again for taking the time to assist.

 

[CyberSimian]

it was the same every time, until I left the outgoing cable off (it isn't plugged into anything at the other end) and the HD channels appeared!

That is weird . I must remember that as a possible cause if others have a similar problem in the future.

One possible explanation is that the outgoing cable was acting as a notch filter. It is possible to create a simple notch filter for RF frequencies by connecting a piece of co-axial cable via a "T" junction. The length of the T piece determines which frequencies are cancelled out. Perhaps the circuit layout on the TBS card made the outgoing cable appear electrically as a T piece, and it was exactly the right length to cancel out the DVB-T2 MUX. See this page for more details about notch filters.

Anyway, I am glad that the problem is now fixed.

-- from CyberSimian in the UK

 

[SimonP]

I thought it worth mentioning in case someone else with the same problem finds this thread. Not even a long cable either, only 3-4m. Very weird.