[linux-dvb] [PATCH] 8PSK/BPSK DVB-S/S2 support

Johannes Stezenbach js at linuxtv.org
Sat Feb 18 23:50:48 CET 2006

On Sat, Feb 18, 2006, Alan Nisota wrote:
> This is a trivial patch which adds capabilities for 8PSK (QPSK_8) and
> BPSK (QPSK_B) modes to frontend .h
> The change does not affect the size of the dvb_frontend_parameters, so
> it is backwards compatible with all software (for cards that don't
> utilize the 'modulation' value.
> I am not sure what to do about mixing software that does not support
> 8PSK modulation with hardware that does.  In this case, there is the
> small chance that a program does not initialize the
> dvb_frontend_parameters, structure and that the value in the
> 'modulation' variable equals QPSK_8 or QPSK_B in which case any card
> looking for these will be switched to the wrong mode.

Hm, breaking source compatibility is not nice :-(

> Perhaps an additional 'union' is necessary to prevent that, however,
> these cards obey  qpsk commands as well, and software I've looked at
> seems to assume a card uses only one of the available modes
> (qpsk/qam/vsb/ofdm) so it would mean a lot more coding to applications
> to treat 8PSK/BPSK as different from QPSK.

I'm undecided. Does anyone have an opinion?

Is these change sufficient to add full DVB-S2 support, or are
further changes necessary? If so, I'd prefer them to be added
in one go.


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