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

Oliver Endriss o.endriss at gmx.de
Sun Dec 4 13:27:04 CET 2005


Klaus Schmidinger wrote:
> Oliver Endriss wrote:
> > 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
> 
> Yes, it's a Rev 1.3 FuSi card (sorry, I forgot to mention that).
> Note that I'm using the DVB driver on kernel 2.4. However, I
> didn't see anything in the dvb-kernel source that would indicate
> that something has been fixed in that area since the old driver.
> 
> > 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?
> 
> I didn't find one on either of these positions, but there is one
> on S28.5E:
> 
> ManToVa Puntosat:12546:vC34:S28.5E:2893:512:513:0:0:1:0:0:0
> 
> I just tried tuning to this one with my FF card and got no picture
> or sound. With my budget card I can receive it.

Sorry, I can only receive 13E and 19.2E here.
Thanks to Wolfgang I found some FTA radio stations on Hotbird 6.

I did some tests using
BBC WS English;BBC WS:11131:vC34:S13.0E:5630:0:457=eng:0:0:5003:318:3801:0

Test results:
ALPS BSRU6 (old Nova-S)				ok
ALPS BSRU6 (FF rev. 2.1):			ok
Grundig 29504-451 (Activy budget GR)		failed [1]
ALPS BSRV2 (FF rev. 1.3)			failed [2]

[1] as expected, tuner supports 12..30 Msymbols/s only
[2] tuner supports 1..45 Msymbols/s

Imho there is a bug in the ves1x93 driver for low symbol rates.
Unfortunately there is no information about 1893 register programming.

Oliver

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