[linux-dvb] Poorly Siemens DVB-C

Johannes Stezenbach js at linuxtv.org
Mon Aug 8 22:27:02 CEST 2005


On Sun, Aug 07, 2005 Gavin Hamill wrote:
> I have one of these classic cards (yay! RGB output! :) and the tuning has 
> suddenly got VERY slow - it'll take easily a minute to lock onto most 
> signals, and often up to four minutes. (!)
> 
> I've already been through the PWM adjustment and will usually end up with 
> "ves1820: AFC (0) 0Hz" or "ves1820: AFC (-1) 6789Hz" so I know the PWM value 
> is set as accurately as it can be... unfortunately I am having to load 
> dvb-core with dvb_override_tune_delay=20000 
> 
> czap testy
> using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
>   6 testy:595000000:INVERSION_AUTO:6952000:FEC_AUTO:QAM_64:640:641
>   6 testy: f 595000000, s 6952000, i 2, fec 9, qam 3, v 0x280, a 0x281
> status 00 | signal 8080 | snr b6b6 | ber 00029220 | unc 0000001f |
> status 00 | signal ffff | snr b6b6 | ber 00029220 | unc ffffffff |
..
> status 1f | signal ffff | snr e8e8 | ber 00023744 | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr d9d9 | ber 00023744 | unc 00000000 | FE_HAS_LOCK

signal ffff looks suspicous. Could it be that your cable company
increased the signal level too much? Does a different card or
a set-top-box work with the signal?

I've not much knowledge about the tuner on the Siemens card, but you could try
to play with the AGC settings, reg0x01 in ves1820.c, where the data sheet
differs from the code, BTW:

AGCR[7:0] Modulation
   140     16-QAM
   106     32-QAM
   106     64-QAM
   120    128-QAM
    92    256-QAM

Johannes




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