UK HD signal corruption - gooman

Help and support for HDHomeRun DVR and HDHomeRun software for Windows 10, Mac, Android, XBox, etc.
gooman
Posts: 160
Joined: Tue Dec 27, 2016 4:03 am

Re: UK HD signal corruption - gooman

Postby gooman » Thu Mar 15, 2018 3:28 am

What are your numbers for Signal Quality and Symbol Quality and are they constant or bounce around a lot (more than 5%-10%)?
Signal Quality is constant over a short time frame, but varies slowly between 94% and 100% over the course of a day. Symbol Quality is consistently 100%.

That's all until a signal outage incident. Then, Signal Quality drops to below 50% and bounces, or even to 0%, and Symbol Quality drops to 0%. Screen is corrupted, or freezes for duration of outage. This happens for 1-10s and then all is fine again. These outages can occur every few minutes, or be single isolated incidents and not occur again for at least an hour. They *only* happen on HD channels (all on the same multiplex on ch21).

They don't occur at all on any other device on the same antenna (TV or PVR) with a built-in tuner, nor do they occur for my neighbours.

wurensh
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Joined: Thu Mar 01, 2018 3:53 pm

Re: UK HD signal corruption - gooman

Postby wurensh » Thu Mar 15, 2018 6:35 am

Your symptoms sound *exactly* the same as mine.

To stop the drop outs on HD channels (channel 33 typically) I have to attenuate my signal strength (as measured/shown in the debug gui app) down to about 50%. The signal quality then stays steady around 60% and symbol quality stays constant at 100%.

Ultimately it's a constant signal quality and symbol quality you want -- it doesn't really matter if your signal strength is at 90% or 60% to achieve it.

For the unattenuated signal I generally get signal strength of 93%+ The signal quality will also be in the high 80s/low 90s however in this mode the signal quality tends to 'flap' and drops out as you've noticed.

I also take back what I said about the HDHR5 coping better with the unattenuated signal -- I'd only had it a few days when I wrote the original post. I now have to use the attenuator on it too to stop the drop outs on the HD channels. The HDHR5 unit I'm using is also a replacement - the original one had to be returned for an unrelated issue.

gooman
Posts: 160
Joined: Tue Dec 27, 2016 4:03 am

Re: UK HD signal corruption - gooman

Postby gooman » Thu Mar 15, 2018 8:14 am

Interesting. A capture file is with Support at present as they want to check that "the HDHomeRun is correctly handling any frequency offset on the channel based on the tuning information in the broadcast".

If that comes back positive, then I'll definitely try an attenuator - though if I need one on the edge of a transmitter footprint, I'd suggest that almost everyone will need one and it should come in the box!

elabra
Posts: 179
Joined: Wed May 27, 2015 2:32 pm

Re: UK HD signal corruption - gooman

Postby elabra » Thu Mar 15, 2018 3:04 pm

Interesting. A capture file is with Support at present as they want to check that "the HDHomeRun is correctly handling any frequency offset on the channel based on the tuning information in the broadcast".

If that comes back positive, then I'll definitely try an attenuator - though if I need one on the edge of a transmitter footprint, I'd suggest that almost everyone will need one and it should come in the box!
If you want a quick test and have a spare coax splitter laying around you may want to add that to the existing cable run - a splitter will also bring down the signal a few Db's and might help if your signal is too strong.

andrewpmoore2
Posts: 17
Joined: Mon Apr 30, 2018 3:04 am

Re: UK HD signal corruption - gooman

Postby andrewpmoore2 » Mon Apr 30, 2018 3:08 am

Did you ever resolve this. I'm having exactly the same issue.

Aerial gets pretty much 100% quality and signal (I'm about 18 miles for the transmitter) and can watch tv perfectly when the aerial is straight into the TV, but on the HDHomerun get frequent breakup/corruption of the picture and the hdhomerun signal meter app will show the quality dropping to 0 for a few seconds.

gooman
Posts: 160
Joined: Tue Dec 27, 2016 4:03 am

Re: UK HD signal corruption - gooman

Postby gooman » Mon Apr 30, 2018 3:36 am

No, I'm still getting the problem.

Nick is looking into it. The latest theory is that the signal might be too strong. The diagnostic logs don't yet note when the signal is too strong, so Nick is planning to issue a new firmware image that notes this.

If it is the source of the problem, then I'm amazed. I'm 21 miles from the Sandy Heath transmitter, in which case *anyone* closer to this transmitter would have the same problem using an HDHR.

andrewpmoore2
Posts: 17
Joined: Mon Apr 30, 2018 3:04 am

Re: UK HD signal corruption - gooman

Postby andrewpmoore2 » Mon Apr 30, 2018 3:45 am

Yes it'd surprise me too as again I'm at a similar distance to Emley Moor. I had my aerial moved onto the roof to try and improve things as it had been in the loft and I'd assumed the issue was because the signal wasn't strong enough (it used to be between 50% and 80%).

So far support have suggested a highpass filter. I've gone one ordered to see if it helps, but don't really see why I should be paying for that given that other devices work perfectly fine with the signal without one.

gooman
Posts: 160
Joined: Tue Dec 27, 2016 4:03 am

Re: UK HD signal corruption - gooman

Postby gooman » Mon Apr 30, 2018 5:49 am

You mean a 4G 800MHz filter? That was suggested to me too. I managed to get one to try for free, and it made no difference ...

No surprise really, since the major problem I'm getting is on HD channels which are at the low end of the Freeview spectrum at aroun 474MHz, rather than the high end.

andrewpmoore2
Posts: 17
Joined: Mon Apr 30, 2018 3:04 am

Re: UK HD signal corruption - gooman

Postby andrewpmoore2 » Mon Apr 30, 2018 5:53 am

No it wasn't an LTE filter (which I think is a 4g filter).

They suggested the first item on this page:
http://www.kcb.co.uk/shop2/contents/en-uk/d70.html

Which says it's designed mainly to reject all signals below 30MHz, so sounds like it's the opposite end of the spectrum from the 4g one if I've read that correctly.

gooman
Posts: 160
Joined: Tue Dec 27, 2016 4:03 am

Re: UK HD signal corruption - gooman

Postby gooman » Mon Apr 30, 2018 9:34 am

I think the main benefit of that filter would be the braid breaker. The lower end of the Freeview spectrum is at 474MHz, so I can't see what good it would do to reject signals below 30MHz.

The braid breaker circuit stops spurious signals being picked up in the shielding of the downlead from a roof-mounted antenna. I have one, and it certainly made the signal better, but doesn't resolve the problem entirely.

Personally, I wouldn't go spending any more money on trying to resolve something that hasn't yet been accurately diagnosed.

I'm waiting on Nick's firmware update.

andrewpmoore2
Posts: 17
Joined: Mon Apr 30, 2018 3:04 am

Re: UK HD signal corruption - gooman

Postby andrewpmoore2 » Tue May 01, 2018 6:57 am

Totally agree, I don't really feel like I should have to be spending any extra anyway to get it working when other devices work perfectly fine without needing extra hardware attached.

If you get an update, can you let me know and I'll do the same if I find anything out.
I'm using the new 4 tuner hdhomerun, which one are you using?

gooman
Posts: 160
Joined: Tue Dec 27, 2016 4:03 am

Re: UK HD signal corruption - gooman

Postby gooman » Tue May 01, 2018 7:14 am

I'm using the new HDHR5 Connect Duo.

I now have a test version of the firmware that flags over-strength signals, and I'll be getting back to Nick with times of signal corruption failures when they occur so he can match them against the logs.

andrewpmoore2
Posts: 17
Joined: Mon Apr 30, 2018 3:04 am

Re: UK HD signal corruption - gooman

Postby andrewpmoore2 » Tue May 01, 2018 7:20 am

Ah good.
Mine's the same but the quad version.
Let's hope he finds something useful from it.

gooman
Posts: 160
Joined: Tue Dec 27, 2016 4:03 am

Re: UK HD signal corruption - gooman

Postby gooman » Wed May 02, 2018 9:09 am

Submitted info back to Nick - awaiting results.

andrewpmoore2
Posts: 17
Joined: Mon Apr 30, 2018 3:04 am

Re: UK HD signal corruption - gooman

Postby andrewpmoore2 » Wed May 02, 2018 9:14 am

I got my high pass filter today so I'll report if it does bring any improvements once I've tested it.


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