[linux-dvb] [PATCH] cx24116 DVB-S modulation fix
obi at linuxtv.org
Tue Oct 14 23:05:45 CEST 2008
Christophe Thommeret wrote:
> dvbscan initial tuning data files for DVB-S don't have an entry for
> modulation. So an app like kaffeine simply set modulation to QAM_AUTO.
> Why not QPSK, you ask? Simply because DVB-S standard allows QPSK and 16QAM.
> Maybe there is not a single 16QAM TP all over the world, but it's still a
> valid modulation for DVB-S.
> So, we set modulation to QAM_AUTO when it's unknown/unspecified, like in
> dvbscan files (those being also used by kaffeine). And it works pretty well,
> just because most dvb-s can only do QPSK and so force modulation to QPSK
> instead of returning a notsup.
> See this as software QAM_AUTO :)
It simply doesn't make sense to specify QAM_AUTO if dvb_frontend_info.caps
doesn't contain FE_CAN_QAM_AUTO (or FE_CAN_QAM_16 for that matter).
More information about the linux-dvb