Documentation/userspace-api/media/dvb/dvb-frontend-parameters.rst

Source file repositories/reference/linux-study-clean/Documentation/userspace-api/media/dvb/dvb-frontend-parameters.rst

File Facts

System
Linux kernel
Corpus path
Documentation/userspace-api/media/dvb/dvb-frontend-parameters.rst
Extension
.rst
Size
3396 bytes
Lines
120
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

struct dvb_frontend_parameters {
	uint32_t frequency;     /* (absolute) frequency in Hz for QAM/OFDM */
		    /* intermediate frequency in kHz for QPSK */
	fe_spectral_inversion_t inversion;
	union {
	    struct dvb_qpsk_parameters qpsk;
	    struct dvb_qam_parameters  qam;
	    struct dvb_ofdm_parameters ofdm;
	    struct dvb_vsb_parameters  vsb;
	} u;
    };

In the case of QPSK frontends the ``frequency`` field specifies the
intermediate frequency, i.e. the offset which is effectively added to
the local oscillator frequency (LOF) of the LNB. The intermediate
frequency has to be specified in units of kHz. For QAM and OFDM
frontends the ``frequency`` specifies the absolute frequency and is
given in Hz.


.. c:type:: dvb_qpsk_parameters

QPSK parameters
===============

For satellite QPSK frontends you have to use the ``dvb_qpsk_parameters``
structure:


.. code-block:: c

     struct dvb_qpsk_parameters {
	 uint32_t        symbol_rate;  /* symbol rate in Symbols per second */
	 fe_code_rate_t  fec_inner;    /* forward error correction (see above) */
     };


.. c:type:: dvb_qam_parameters

QAM parameters
==============

for cable QAM frontend you use the ``dvb_qam_parameters`` structure:


.. code-block:: c

     struct dvb_qam_parameters {
	 uint32_t         symbol_rate; /* symbol rate in Symbols per second */
	 fe_code_rate_t   fec_inner;   /* forward error correction (see above) */
	 fe_modulation_t  modulation;  /* modulation type (see above) */
     };


.. c:type:: dvb_vsb_parameters

VSB parameters
==============

ATSC frontends are supported by the ``dvb_vsb_parameters`` structure:


.. code-block:: c

    struct dvb_vsb_parameters {
	fe_modulation_t modulation; /* modulation type (see above) */
    };


.. c:type:: dvb_ofdm_parameters

Annotation

Implementation Notes