[linux-dvb] ves1820 FEC off? EN 300 468 -> cable:has inner fec,
t.schorpp at gmx.de
Mon Jul 25 15:00:59 CEST 2005
Robert Schlabbach wrote:
> From: "thomas schorpp" <t.schorpp at gmx.de>
>>in 429 the framing shows only outer r-s fec.
>>the latest 468 standard says we HAVE inner fec(!)
> No, it just defines a way to indicate an inner FEC method through the DVB
> Service Information. But since there is no inner FEC method defined for the
> DVB-C transmission standard, the only possible value you can use is:
>>Table 35: Inner FEC scheme
>>1111 no conv. coding
>>i'll implement this in the driver until weekend
> What do you want to implement? I suggest you start by examining the DVB
> Service Information you receive (try e.g. dvbsnoop). I'm 99.99% sure you'll
> find "no conv. coding" indicated in your cable delivery system descriptors.
will do, thx.
>>-if- someone gets me programming registers and values or a full
>>datasheet, theres no on the web, or i try using the ves1x93 data...
> The VES1820 is a demodulator for the DVB-C standard and thus has no inner
> FEC (Viterbi) decoder. The circuits for this are simply not there, period.
> Stop thinking about inner FEC, it is definitely _not_ the problem you are
thx for clarifying that.
i was wondering about this in ves1820.c:
static int ves1820_read_status(struct dvb_frontend* fe, fe_status_t* status)
struct ves1820_state* state = fe->demodulator_priv;
*status = 0;
sync = ves1820_readreg(state, 0x11);
if (sync & 1)
*status |= FE_HAS_SIGNAL;
if (sync & 2)
*status |= FE_HAS_CARRIER;
if (sync & 2) /* XXX FIXME! */ <----???
*status |= FE_HAS_VITERBI;
many thx to all.
> Robert Schlabbach
> e-mail: robert_s at gmx.net
> Berlin, Germany
More information about the linux-dvb