SAT>IP tuner LNB offset settings

[fe31nz]

I have just installed DVBViewer Pro, intending to use it with tuners on other PCs on my network via SAT>IP. For testing, I have a spare PC set up as a Ubuntu 16.04 box with a DVB-T tuner on it. When I run minisatip on that box, DVBViewer has no problems using that DVB-T tuner to play all the channels available from the four DVB-T transmitters I receive.

 

So I next wanted to test using my two DVB-S/S2 tuners on my main MythTV box. These are normally used by MythTV, but it is set in the mode where it makes the tuners available for other use when it does not need them. So I can run minisatip on that box (Mythbuntu 14.04) to make the DVB-S/S2 tuners available to DVBViewer. Initially I am trying to use one of the DVB-S/S2 tuners to tune to the free-to-air Freeview DVB-S channels, which are available on two transponders of the Optus D1 satellite (see the attached DVB-S_1600_Freeview.ini file). The Lyngsat page for Optus D1 is here:

 

http://www.lyngsat.com/Optus-D1.html

 

I am loading the ini file in TransEdit v4.1.2 and telling it to scan the first frequency specified in the ini file, 12456 kHz. The results are not as expected. When minisatip is running on my TeVii S470 card, I get a set of channels that correspond to the Sky New Zealand 12608 kHz tranponder (all encrypted). On my TBS 5922 tuner, I do not get a signal lock. When I look at the minisatip log and the Wireshark capture of the RTSP packet traffic, I can see that TransEdit is sending tuning requests in the RTSP SETUP packets like this:

 

SETUP rtsp://10.0.2.4:554/?src=1&freq=12456&msys=dvbs&plts=off&fec=34&pol=h&ro=0.35&sr=22500&mtype=qpsk RTSP/1.0\r\n

 

The value of the freq field is set to 12456 kHz. Since the SETUP packets do not allow for any options to set the LNB offset frequency, I am guessing that the freq= value needs to have the LNB offset (10750 kHz for my dish) subtracted from it to get the right frequency. So I also tried setting 1706 = 12456 - 10750 as the frequency for TransEdit to scan, but that did not work either. So I clearly am missing something about how SAT>IP or DVBViewer handles the LNB offset. The DVB-S_1600_Freeview.ini file has the LNB settings for my LNB type - just a simple offset and nothing else (only LOF1 set to 10750). Changing that value does not seem to affect the freq= value sent by TransEdit.

 

So does anyone see what I am getting wrong here?

support.zip

DVB-S_1600_Freeview.ini

[Griga]

So I clearly am missing something about how SAT>IP or DVBViewer handles the LNB offset.

 

They don't handle it at all. In a Sat>IP setup it is up to the server / physical tuner to calculate the intermediate frequency from the satellite frequency and the local oscillator frequency (LOF) of the LNB.

 

With other words: The server / tuner must be set up for the LNB type / LOF, not the client. The client sends the satellite frequency, the server / tuner subtracts the LOF (exactly what you did: 12456 - 10750 = 1706 MHz) and tunes the resulting intermediate frequency.

[fe31nz]

Thanks, I will delve into minisatip and see what it is doing for LNB setup.

[fe31nz]

I found the problem in minisatip - it only allowed use of standard LNBs on a default LOF of 10600 MHz, without any way to configure that frequency. So I have done a patch to add a command line option to set the LOF and it now works fine with DVBViewer Pro and TransEdit using my TBS 5922 DVB-S2 card. I have submitted that patch and hope a new version of minisatip will incorporate it.