[mythtv-users] Fwd: Unicable problems

Mike Perkins mikep at randomtraveller.org.uk
Mon May 23 21:58:52 UTC 2022

> -------- Weitergeleitete Nachricht --------
> Betreff:     Unicable problems
> Datum:     Wed, 18 May 2022 23:14:27 +0200
> Von:     Matthias Thyroff <matthias at thyroff.net>
> An:     mythtv-users at mythtv.org
> Hi everybody,
> after years using my mythbox with great success and relatively little suffering, I had to move my 
> server to a location a bit further away from the sat dish and there is only one cable available so I 
> decided to switch to unicable and this is quite a headache... I think I have several problems, I am 
> not even sure where to start. Maybe I first describe what I have:
> I have a Selfsat H50DCSS antenna - a flat satellite antenna with incorporated 2x legacy and 1x 
> unicable connections.
> I have the unicable connection fed through the window and there connected to the inhose coax cable 
> that originally was laid for cable tv. At the location of the receiver at the other end of that 
> cable, I have a 1-to-4 splitter (alternatively 1-to-2), connected to my SAT inputs - a digital 
> devices cine S2 V6.5 card plus one DuoFlex S2 extension card (which does not seem to work, I keep 
> that pending for later).
> I am also running four loopback devices (link 0:4, 1:5, 2:6, 3:7, this is working) .
> Then I have four input cards defined, one for each loopback device, from adapter 4 to 7.
> Card 1: /dev/dvb/adapter4/frontent0; type DVB-S, delivery system dvb-s2, DiSEqC Unicable (Userband 
> 0, 1210MHz, Pin -1, repetitions I tried 1, or 9, or 15, works all the same), type LNB (Universal-LNB 
> (Europe))
> Card 2: same for adapter 5, except Userband 1, 1420.
> Card 3: same for adapter 6, except Userband 2, 1680,
> Card 4: same for adapter 7, except Userband 3, 2040.
> Video Source, one defined. Name "Unicable". Only EIT, frequencies europe-west, etc. etc.
> Input connections: Card 1 and 2 connected to unicable, card 3 and 4 for now to "nothing", for later 
> trouble shooting (these to cards error out, the other two cards show as available in the frontend).
> Input connections are configured fast tuning "never".
> I think that is a relatively complete description of the setup.
> Scanning for channels was quite difficult - I could never do a complete scan (tuned), so I switched 
> to a legacy input on the antenna, then I scanned, and once I had the transponders, I could switch 
> back to unicable and do a full scan of all known transponders. I would get about 600 channels less 
> and many transponders which would have signal on the legacy output of the antenna do not have signal 
> on the Unicable output, but nothing important seems to be missing, so that is OK for now. I also 
> have optimized the antenna orientation with a sat finder, I think that made it much better. With the 
> 4x Splitter while scanning, I get about 64% Signal and S/N of about 25%, if that means anything. 
> Reception seems to be stable for now.
> Several things seem to not work very well, but right now only one problem is consistant and 
> (finally, thanks for reading up to here) I dare to ask for help:
> It seems I can only watch or record one channel even though I have two working cards. Once a program 
> is recording, I can still enter live tv, I see the same channel as is recording, I can switch 
> between the two sources (Called SAT#1 and SAT#2), but I cannot change channel, neither on the card 
> busy with the recording (I have configured the input to allow for 2 concurrent recordings, so I 
> should be able to switch to another channel on the multiplex). nor can I change the channel on the 
> second card, it will also only tune to the channel that is currently recorded on the other card.
> One solution that occurs to me is to create another video source for the second card - I have not 
> tried, I do not know whether that would work but that was not necessary in the past, one video 
> source would work for several tuner cards. So I hope to get a better suggestion from you.
> Thanks a lot in advance!
On 23/05/2022 20:55, Matthias Thyroff wrote:
> Hello everybody,
> let's see, I am still having problems with Unicable/SCR on my mythbox.
> I don't find anything almost on the internet regarding mythtv and unicable, nothing very recent, is 
> anybody using this?
> My problem is that even if I have several receiver cards, I can only tune in to one channel.
> I have tried my own suggestion from below and created a second videosource... the same, if I record 
> one channel, I also can watch only this channel even though I have more than one receiver card.
> In my original mail I forgot to mention: I am on myth version 0.31, on ubuntu focal.
> Is Karl Egly here? I saw that the original unicable patches came from him, I wonder if this part of 
> the code is alive...
> Thanks for all suggestions in advance,
I don't use satellite myself but, seeing your original message, I had a quick look at the 
specification for Unicable on Wikipedia.

It seems to me that Unicable uses a head end which combines the output from the original LNBs on the 
dish(es), assigning each a separate intermediate frequency which is then fed down the same cable.

I think the problem you are facing is that mythtv is scanning the /original/ satellite frequencies 
and not the ones presented by unicable. I assume that the patches you mention above correct this 
problem and supply the correct frequencies.

The selection of channels, etc should be handled as normal by the DISEQC code but someone else will 
need to look at that and tell you if that is enough for Unicable.

I had never heard of Unicable before but, to me, it looks like a clever way of solving the problem 
of multiple satellite feeds. If your problems can be solved for mythtv then I might investigate 
using it myself.


Mike Perkins

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