[linux-dvb] Re: [dvbtools-devel] dvbtune-0.5 inverts diseqc pol and band bits

Nico Sabbi nicola_sabbi at fastwebnet.it
Mon Apr 30 20:31:56 CEST 2007

Zoilo Gomez wrote:

>dvbtune-0.5 source apparently contains a bug where it inverts both the 
>polarization and high/low band bits in the diseqc command ... as I 
>cannot find any info on this anywhere, I am posting my results here.
>I discovered this while using a KNC1 DVB-S card to compare diseqc 
>handling with VP1034 (because diseqc is not (yet) working on my VP1034). 
>I am using a Spaun 17089-NF 16-input switch (4 sats) + 8 outputs, which 
>supports up to Diseqc 2.0.
>First I got confused, because the Mantis driver simultaneously uses the 
>old 18/13V+22kHz method to control polarization and band, as well as the 
>Diseqc method. So for a while I believed that Diseqc was (partially) 
>working, until I found out that in fact 18/13V+22kHz seems to be 
>responsible for the (partial) job!
>As a result of no Diseqc-functionality on VP1034, it seems that with 
>VP1034 on my switch, sat-selection is always fixed to sat=1 (makes 
>sense, = the first 4 inputs, which happens to be Hotbird 13.0E in my 
>setup), however input selection from the 4 feeds V/H and H/L works fine 
>and correctly, although based on 18/13V+22kHz.
>When I compared this with my KNC-1 DVB-S card (to find out why 
>Sat-selection is not working with VP1034), I found that with KNC1, 
>Sat-selection does switch to Sat=2 (so it must be using diseqc), but 
>polarization and band-selection were inverted ... So when I issued the 
>following command:
>"dvbtune -D 2 -f 10832000 -p H -s 22000"
>I found that it was actually selecting sat=2 pol=V band=H ("e0 10 38 
>f5"= switch input 7), instead of sat=2 pol=H band=L (= switch input 6 / 
>"e0 10 38 f6").
>The Diseqc-specs at 
>(table on page 13) confirm that dvbtune is in fact sending the wrong 
>With a patched dvbtune (pol-bit and band-bit both inverted) it works OK, 
>and is also according to the Eutelsat specs.
>Hope someone benefits from this.
nice, but i don't see the patch, but I wonder how I can have been using 
my sat switch
for years

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