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

Oliver Endriss o.endriss at gmx.de
Sat Dec 3 16:27:26 CET 2005


Klaus Schmidinger wrote:
> Full featured DVB cards (Siemens/Technotrend AV7110 design)
> apparently have trouble with receiving channels at very low
> symbol rates.

Rev 1.6 cards (Grundig tuner) are known to have trouble with low symbol
rates. Never heard about problems with other revisions.

> 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)?

Either symbol_rate_min is wrong for your FF card (Rev 1.3?) or the
driver is broken for low-symbol rates.
Anyway, we have to fix the driver.

Is there any low-symbol-rate FTA channel on 19.2E or 13E?

Oliver

-- 
--------------------------------------------------------
VDR Remote Plugin available at
http://www.escape-edv.de/endriss/vdr/
--------------------------------------------------------



More information about the linux-dvb mailing list