TVH 4.2.8-36 using PCTV 461e satellite decoder has started producing continuity errors and reporting 0% signal quality

Martin Underwood

I've got TVH 4.2.8-36 set up on a Raspberry Pi4 with Raspberry Pi OS from NOOBS 3.5.0 (uname -a reports "5.10.17-v7l+ #1403 SMP Mon Feb 22 11:33:35 GMT 2021 armv7l GNU/Linux").

I've got three tuners: PCTV 461e (sat, DVD-S2), PCTV 292e (terrestrial, DVB-T2) and Hauppauge WinTV Nova (terr, DVB-T).

The configuration has been working for about a year. I'm not aware of any recent change.

But as of a couple of days ago, recordings on satellite (Sky 28.2) are getting an average of about 200 data errors (on Digital Video Recorder | Finished Recordings for a recording) and recordings sometimes finish early: the post-processor event still runs at the expected end time but the recording file was last written some time (eg 20 minutes) before.

The Status page is showing something new: when a satellite recording is in progress, it used to report approx SNR = 15 dB and Signal Strength = -20 as digits. Now it is showing percentage "progress bars": SNR is 0% (ouch!) and Signal Strength is around 94%. The terrestrial devices, when I record using them, still report numerical SNR/Signal.

I've tried powering off/on the Pi and the external PSU for the PCTV 461e. I've checked with another satellite cable attached to the other LNB on my dish. Still the same.

Now here's the weird thing. I also have a Raspberry Pi3 with Raspian Stretch and TVH 4.2.8-36 - I used to use this device before I got the Pi4. And that seems to work fine: negligible data errors and Status page reporting as figures rather than %. That seems to suggest that the PCTV 491e and the satellite signal are OK.

Any thoughts as to what could have suddenly gone wrong to the Pi4 system that (AFAIK) hasn't changed.

Ron L

The change is Stats reporting would tend to indicate a driver has changed as a result of a kernel update perhaps. Has this occurred? A kernel update to the system? If the device is no longer operating correctly after such kernel update I would investigate any commit changes to the driver module for that device to determine if perhaps a bug has been introduced.

Martin Underwood

After a bit more testing, I can see that after the Pi is rebooted (which obviously restarts TVH) the stats are initially quoted as numbers if I perform a recording or live-view a TV channel in VLC. But after a few minutes the Stats display changes to % bars.

Martin Underwood

I realised that Ihad changed something: I'd done a "sudo apt update" and "sudo apt full-upgrade". Amongst many package updates, there was also an update of the kernel, from 5.4 to 5.10. If a driver for the PCTV 461e DVB-S2 tuner had been updated in this new kernel, that could explain the symptom.

I've reinstalled RaspiOS from scratch. I'd installed from NOOBS last time which creates several little partitions that prevent the system partition being resized and I'd installed to a 16 GB card which gave a rather small system partition, so I'd been thinking about reinstalling before I had the problem discussed here.

And now, with 5.4.83, everything is working fine. I'll be a bit cautious about upgrading to the latest packages. Or at least, I'll make sure I make an image of the SD card before I do an upgrade. I'd been doing that religiously, but then I got out of the habit...

I've kept the old SD card with 5.10, and I might experiment with downgrading to 5.4 kernel: apparently "rpi-update 453e49bdd87325369b462b40e809d5f3187df21d" will revert the kernel.

If it is a kernel problem, I wonder how we report it to PCTV in case they have supplied a duff driver to the organisations that build kernels for various flavours of UNIX.

One thing that I have noticed with TVH is that after a reboot I initially get recordings with no (or very few) continuuity errors reported. But after a few days,all the tuners (DVB-S2, DVB-T2 and DVB-T) start to report continuity errors at an every-increasing rate. I've got into the habit of rebooting the Pi every couple of days. That shouldn't be necessary. Am I right in deducing that because it affects all tuners and not just one, it coudl be a TVH problem rather than an individual driver/tuner problem?