[linux-dvb] Switching Modulation type

Johannes Stezenbach js at linuxtv.org
Thu Feb 17 20:15:50 CET 2005

Holger Waechtler wrote:
> Rusty Scott wrote:
> > I'm looking at supporting VSB and QAM on the same card, however it appears that
> > modulation type is munged into a union dependant on what type of modulation you
> > already expect.  Am I missing something? (granted I am fairly new to the DVB
> > driver world)  Is there some other mechanism I haven't found yet that is used
> > for changing modulation types other than the struct dvb_frontend_parameters
> > stuff?

(repaired broken quoting)

> The union type does not specifies the modulation but rather the network 
> type (DVB-S, DVB-T or DVB-C style). Your way out is probably to add a 
> new ATSC union member containing the parameter set you need. Please send 
> us a patch.

The struct dvb_{qpsk,qam,ofdm,vsb}_parameters are simply misnamed.
If your frontend is of type FE_ATSC you always need to pass the
modulation type in struct dvb_frontend_parameters.vsb.modulation,
and you can put any enum fe_modulation value there.

The naming scheme has been cleaned up in the V4 API.


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