Re: [linux-dvb] Help needed...

[Andrea Giuliano <sarkiaponius@alice.it>]

Dear Morgan,

first of all I thank you for your kind answer, and I also thank Octavio 
  Ascanio and Hermann.

Actually, before you answer I solved my problem in a way that seems to 
me very close to your suggestion.

Looking a lyngsat and kingofsat I found that every single channel found 
by dvbscan is on a frequency which is just 19 or 20 units less than the 
one listed on those sites. For example, 11804 on lyngsat corresponds to 
11785=11804-19 on the dvbscan output.

So I started trying different values of frequency, but without results. 
Finally, I really can't say why, I tried to change "V" to "H" ... et 
voilà: I could be able to see RaiNews24!

Then I tried exactly what you suggested: the -c option. This way I got, 
with some minor problems, a list of RAI channels on 11804 and 11766, but 
still with the wrong frequencies.

To be precise, here is a working channels.conf file which I can now use 
to watch and record RAI channels perfectly fine:

nettuno1:11785:h:0:27500:519:657:3410
nettuno2:11785:h:0:27500:513:651:3410
rai1:11747:h:0:27500:512:650:3401
rai2:11747:h:0:27500:513:651:3402
rai3:11747:h:0:27500:514:652:3403
raiedu1:11785:h:0:27500:514:652:3527
raiedu2:11747:h:0:27500:518:656:3406
raigulp:11785:h:0:27500:522:663:3410
raimed:11747:h:0:27500:515:653:3404
rainews24:11785:h:0:27500:516:654:3521
senato:11747:h:0:27500:8190:92:3408

You will notice the "h" polarity. According to lyngsat, there are no 
channels on "11785 H", or, if any, they definitely are not RAI channels. 
The same, if I remember correctly, applies for "11747 H".

My practical conclusion is: "11804 V" stands for "11875 H" and "11766 V" 
stands for "11747 H". No other way to get things working.

To some extents, my results are in some accord with your suggestions. 
Actually, the cable should be about 30 meters long. I can't say anything 
about the point 1) of your answer, but I also have many foreign channels 
tuned with the wrong frequency, but the right polarity. At present it 
would take a bit of time to show you some example of this, I'll dot my 
best about this.

Anyway, now I got a practical result, and that's a start.

Many thanks and best regards.

Morgan Tørvolt wrote:
> On 22/03/2008, Andrea Giuliano <sarkiaponius@alice.it> wrote:
>> Hi,
>>
>>  I can szap many free channels from Hotbird 13E, but none on some
>>  frequencies. For example, if the "test" file just contains the line:
>>
>>     S 11766000 V 27500000 2/3
>>
>>  that I took from http://www.lyngsat.com/hotbird.html as many other which
>>  instead work percectly, the command:
>>
>>     scan test > channels.conf
>>
>>  alway gives the following output:
>>
>>  scanning prova
>>  using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
>>  initial transponder 11766000 V 27500000 2
>>   >>> tune to: 11766:v:0:27500
>>  WARNING: >>> tuning failed!!!
>>   >>> tune to: 11766:v:0:27500 (tuning failed)
>>  WARNING: >>> tuning failed!!!
>>  ERROR: initial tuning failed
>>  dumping lists (0 services)
>>  Done.
>>
>>  On the other hand, if I put manually some lines in channels.conf for
>>  such a frequency, I can zap to those channels, but in most cases I watch
>>  a different channel, not the one I expected to see.
>>
>>  This doesn't happen on other frequencies.
>>
>>  May be of some help the fact that I'm writing from Italy, and I cannot
>>  get channels from the scan for the most important italian channels: in
>>  particular, none of RAI network, nor Mediaset network, the biggest
>>  network in Italy.
>>
>>  Also, the signal became rather good after I bought an amplifier.
>>  Actually, I can see and record perfectly fine many channels. I don't
>>  think I have signal strength problems.
>>
>>  Any hint will be very much appreciated.
>>
>>  Best regards.
>>
>>  --
>>  Andrea
>>
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> 
> Getting a different mux is only possible int a few very special cases.
> 1. Your LNB is 90 degrees off, giving vertical where you should have
> horizontal and vice verca.
> 2. You get the wrong polarization or frequency, possibly because of a
> too long cable dampening the 18V or something like that so that the
> LNB does not switch.
> 
> This is easy to check actually. Use zap to go to the "wrong" mux, and
> then use dvbscan -c (scan current mux) to get a listing of the
> channels on the mux. Then locate the mux using lyngsat. You will then
> see if there is a difference in polarization or frequency that can be
> explained by a error in lo frequency (if the frequency is off by
> 10600-9750=850MHz) or polarization. I am quite confident that you will
> find one of these to be the case. The frequency can be a bit away from
> 850MHz since the tuner is usually able to achieve sync with a lot of
> offset (I have seen a tuner sync with more than 15MHz offset).
> 
> The error can as mentioned be caused by a long cable, but a faulty LNB
> or tuner-card is of course also a possible explaination. Check if an
> ordinary stb works.
> 
> -Morgan-


-- 
Andrea


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