[linux-dvb] Q2: dvb api 3 - FE_ATSC

Patrick Boettcher patrick.boettcher at desy.de
Mon Aug 22 22:51:33 CEST 2005

On Mon, 22 Aug 2005, Rainer.scherg wrote:

> Patrick Boettcher schrieb:
>> On Mon, 22 Aug 2005, Rainer.scherg wrote:
>>> typedef enum fe_type {
>>>     FE_QPSK,
>>>     FE_QAM,
>>>     FE_OFDM,
>>>     FE_ATSC
> [...]
>>> ATSC supports several modulations...
>>> Shouldn't there be the modulation named  (e.g. VSB)?
>>  No, because an ATSC demodulator is capable of decoding VSB and QAM 
>> signals.
> OK, but querying  GET_INFO from frontend.
> I cannot decide directly whether to use
>   struct dvb_frontend_parameters {
> 		struct dvb_qam_parameters  qam;
> 		struct dvb_vsb_parameters  vsb;
> In this case I have to crosscheck capabilities,
> (which would make fe_type obsolete, because I
> always could check for capabilities only).

Aah, now I see your problem:

So, no you must not fill or read dvb_qam_parameters when passing it to a 
FE_ATSC frontend. If you want to tune to a QAM signal with an FE_ATSC you 
have to set vsb.modulation to QAM_256. Just like when you would tune to 
QPSK when setting up a COFDM-frontend.

Only the vsb-field is handled by FE_ATSC.


   Mail: patrick.boettcher at desy.de
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