[linux-dvb] Low symbol rates on FF DVB cards

Klaus Schmidinger Klaus.Schmidinger at cadsoft.de
Sat Dec 3 14:30:30 CET 2005


Full featured DVB cards (Siemens/Technotrend AV7110 design)
apparently have trouble with receiving channels at very low
symbol rates. An example is

   TVS Teleport Bonn;DMV:11535:vC34:S1.0W:5632:308+8190:256=eng,257=eng:0:2:1:65535:1:0

with a symbol rate of 5632 (that transponder isn't always on, though).
My FF DVB card can't receive this channel, so I have to receive it
with a budget card, which is able to handle this symbol rate.

In order to automate this I tried getting the dvb_frontend_info
and checked its symbol_rate_min, hoping that I could use this
to find out whether a given device could receive a channel with
a given symbol rate.

Unfortunately both my FF card and my budget card report the same
minimum symbol rate:

  name Alps BSRV2
   type 0
   frequency_min 950000
   frequency_max 2150000
   frequency_stepsize 250
   frequency_tolerance 29500
   symbol_rate_min 1000000
   symbol_rate_max 45000000
   symbol_rate_tolerance 0
   notifier_delay 50
   caps 0x000006AF

  name STV0299/TSA5059/SL1935 based
   type 0
   frequency_min 950000
   frequency_max 2150000
   frequency_stepsize 125
   frequency_tolerance 44000
   symbol_rate_min 1000000
   symbol_rate_max 45000000
   symbol_rate_tolerance 500
   notifier_delay 0
   caps 0x400006AF

So I'm afraid I can't use this to make that decision.

Is there anything else I could use, or do I just have to
check for the existence of a video and audio device (which
indicates that there is an MPEG decoder) and in that case
refuse to switch to a channel with a symbol rate of, say,
less than 10000 (in VDR's channels.conf notation)?

Klaus



More information about the linux-dvb mailing list