[mythtv-users] DiSeq problems

Rudy Zijlstra mythtv at edsons.demon.nl
Fri Dec 22 11:48:53 UTC 2006

Rudy Zijlstra wrote:

> Hello,
> I've run out of ideas on this one. My setup: tuner card connected to 
> DiSeq 2.0 switch, with the Diseq switch connected to two satelites, 
> each connected with 4 LNB to the switch (its a 9/16 switch, which 
> supports 2 SAT, and internally generates the tones needed to keep each 
> LNB fixed).
> The STB i have connected in parrallel (setup: DiSeq 1.0 switch with 2 
> LNB) works without problem and receives both Astra 19.2 and Astra 28.2 
> without problem.
> I'm running MythTv 0.20-fixes (on my test system the latest SVN) and 
> am noting that after installing the diseq switch i cannot tune anymore 
> to the channels. I've deleted the DVB tuner and re-installed it. The 
> DVB-S setting now tells the system its connected to a 2-port switch, 
> and the switch it connected to 2 LNB's (universal LNB, tone and 
> voltage). Mythtv-setup seems able to scan astra 19.2, but not able to 
> tune most of astra 28.2. And even this is not always working, as can 
> be seen in the attached log.
> Attached a log from mythtv-setup, and from mythbackend trying to tune 
> (this from operational system, temporarily re-configured to support 
> DiSeq switch in order to test difference between budget and full 
> feature card -> same behaviour).
> Anyone have an idea how to solve this?
> Cheers,
> Rudy
OK, to store for others runing into this problem.

a/ the STB was also not receiving all channels, with > 600 FTA channels 
received, it took some time before i realised the STB was also missing 

b/ Cause of the problems:

When using a Diseqc switch before an LNB, and using a LNB with 4 
outputs, you have to be very carefull with which LNB you use.
There exist both QUAD LNB, and QUATTRO LNB. They are NOT the same.

I was using a QUAD LNB, where i needed to use a QUATTRO LNB.

QUAD LNB has 4 independent LNB into 1 device. Each output can be 
indenpendently controlled by a tuner. Essentially 4 LNB into 1.

QUATTRO LNB has 4 outputs, and each is fixed on a particular setting, so 
you have low-horizontal, low-vertical, high-horizontal and 
high-vertical. These are intended to be used with DiseQc switches.  Each 
output to be connected to the correct input on the switch.

There are very few diseqc switches that can handle a QUAD LNB. There 
seem to be some, but they are rare.

After exhanging the QUAD to an QUATTRO, and connecting the cables 
correctly, all started working.



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