FE_GET_PROPERTY/FE_SET_PROPERTY

DTV property type
DTV properties type
FE_GET_PROPERTY
FE_SET_PROPERTY
Property types
Digital TV property parameters
Properties used on terrestrial delivery systems
Properties used on cable delivery systems
Properties used on satellital delivery systems

This section describes the DVB version 5 extention of the DVB-API, also called "S2API", as this API were added to provide support for DVB-S2. It was designed to be able to replace the old frontend API. Yet, the DISEQC and the capability ioctls weren't implemented yet via the new way.

The typical usage for the FE_GET_PROPERTY/FE_SET_PROPERTY API is to replace the ioctl's were the struct dvb_frontend_parameters were used.

DTV property type

/* Reserved fields should be set to 0 */
struct dtv_property {
	__u32 cmd;
	union {
		__u32 data;
		struct {
			__u8 data[32];
			__u32 len;
			__u32 reserved1[3];
			void *reserved2;
		} buffer;
	} u;
	int result;
} __attribute__ ((packed));

/* num of properties cannot exceed DTV_IOCTL_MAX_MSGS per ioctl */
#define DTV_IOCTL_MAX_MSGS 64

DTV properties type

struct dtv_properties {
	__u32 num;
	struct dtv_property *props;
};

FE_GET_PROPERTY

DESCRIPTION

This ioctl call returns one or more frontend properties. This call only requires read-only access to the device.

SYNOPSIS

int ioctl(int fd, int request = FE_GET_PROPERTY, dtv_properties ⋆props);

PARAMETERS

int fd

File descriptor returned by a previous call to open().

int num

Equals FE_GET_PROPERTY for this command.

struct dtv_property *props

Points to the location where the front-end property commands are stored.

RETURN VALUE

On success 0 is returned, on error -1 and the errno variable is set appropriately. The generic error codes are described at the Generic Error Codes chapter.

EOPNOTSUPP

Property type not supported.

FE_SET_PROPERTY

DESCRIPTION

This ioctl call sets one or more frontend properties. This call only requires read-only access to the device.

SYNOPSIS

int ioctl(int fd, int request = FE_SET_PROPERTY, dtv_properties ⋆props);

PARAMETERS

int fd

File descriptor returned by a previous call to open().

int num

Equals FE_SET_PROPERTY for this command.

struct dtv_property *props

Points to the location where the front-end property commands are stored.

RETURN VALUE

On success 0 is returned, on error -1 and the errno variable is set appropriately. The generic error codes are described at the Generic Error Codes chapter.

EOPNOTSUPP

Property type not supported.

Property types

On FE_GET_PROPERTY/FE_SET_PROPERTY, the actual action is determined by the dtv_property cmd/data pairs. With one single ioctl, is possible to get/set up to 64 properties. The actual meaning of each property is described on the next sections.

The available frontend property types are shown on the next section.

Digital TV property parameters

DTV_UNDEFINED

Used internally. A GET/SET operation for it won't change or return anything.

DTV_TUNE

Interpret the cache of data, build either a traditional frontend tunerequest so we can pass validation in the FE_SET_FRONTEND ioctl.

DTV_CLEAR

Reset a cache of data specific to the frontend here. This does not effect hardware.

DTV_FREQUENCY

Central frequency of the channel.

Notes:

1)For satellital delivery systems, it is measured in kHz. For the other ones, it is measured in Hz.

2)For ISDB-T, the channels are usually transmitted with an offset of 143kHz. E.g. a valid frequncy could be 474143 kHz. The stepping is bound to the bandwidth of the channel which is 6MHz.

3)As in ISDB-Tsb the channel consists of only one or three segments the frequency step is 429kHz, 3*429 respectively. As for ISDB-T the central frequency of the channel is expected.

DTV_MODULATION

Specifies the frontend modulation type for cable and satellite types. The modulation can be one of the types bellow:

 typedef enum fe_modulation {
	QPSK,
	QAM_16,
	QAM_32,
	QAM_64,
	QAM_128,
	QAM_256,
	QAM_AUTO,
	VSB_8,
	VSB_16,
	PSK_8,
	APSK_16,
	APSK_32,
	DQPSK,
 } fe_modulation_t;

DTV_BANDWIDTH_HZ

Bandwidth for the channel, in HZ.

Possible values: 1712000, 5000000, 6000000, 7000000, 8000000, 10000000.

Notes:

1) For ISDB-T it should be always 6000000Hz (6MHz)

2) For ISDB-Tsb it can vary depending on the number of connected segments

3) Bandwidth doesn't apply for DVB-C transmissions, as the bandwidth for DVB-C depends on the symbol rate

4) Bandwidth in ISDB-T is fixed (6MHz) or can be easily derived from other parameters (DTV_ISDBT_SB_SEGMENT_IDX, DTV_ISDBT_SB_SEGMENT_COUNT).

5) DVB-T supports 6, 7 and 8MHz.

6) In addition, DVB-T2 supports 1.172, 5 and 10MHz.

DTV_INVERSION

The Inversion field can take one of these values:

	typedef enum fe_spectral_inversion {
		INVERSION_OFF,
		INVERSION_ON,
		INVERSION_AUTO
	} fe_spectral_inversion_t;
	

It indicates if spectral inversion should be presumed or not. In the automatic setting (INVERSION_AUTO) the hardware will try to figure out the correct setting by itself.

DTV_DISEQC_MASTER

Currently not implemented.

DTV_SYMBOL_RATE

Digital TV symbol rate, in bauds (symbols/second). Used on cable standards.

DTV_INNER_FEC

Used cable/satellite transmissions. The acceptable values are:

typedef enum fe_code_rate {
	FEC_NONE = 0,
	FEC_1_2,
	FEC_2_3,
	FEC_3_4,
	FEC_4_5,
	FEC_5_6,
	FEC_6_7,
	FEC_7_8,
	FEC_8_9,
	FEC_AUTO,
	FEC_3_5,
	FEC_9_10,
} fe_code_rate_t;
	

which correspond to error correction rates of 1/2, 2/3, etc., no error correction or auto detection.

DTV_VOLTAGE

The voltage is usually used with non-DiSEqC capable LNBs to switch the polarzation (horizontal/vertical). When using DiSEqC epuipment this voltage has to be switched consistently to the DiSEqC commands as described in the DiSEqC spec.

		typedef enum fe_sec_voltage {
		SEC_VOLTAGE_13,
		SEC_VOLTAGE_18
		} fe_sec_voltage_t;
	

DTV_TONE

Currently not used.

DTV_PILOT

Sets DVB-S2 pilot

fe_pilot type
typedef enum fe_pilot {
	PILOT_ON,
	PILOT_OFF,
	PILOT_AUTO,
} fe_pilot_t;
		

DTV_ROLLOFF

Sets DVB-S2 rolloff

fe_rolloff type
typedef enum fe_rolloff {
	ROLLOFF_35, /* Implied value in DVB-S, default for DVB-S2 */
	ROLLOFF_20,
	ROLLOFF_25,
	ROLLOFF_AUTO,
} fe_rolloff_t;
		

DTV_DISEQC_SLAVE_REPLY

Currently not implemented.

DTV_FE_CAPABILITY_COUNT

Currently not implemented.

DTV_FE_CAPABILITY

Currently not implemented.

DTV_DELIVERY_SYSTEM

Specifies the type of Delivery system

fe_delivery_system type

Possible values:


typedef enum fe_delivery_system {
	SYS_UNDEFINED,
	SYS_DVBC_ANNEX_A,
	SYS_DVBC_ANNEX_B,
	SYS_DVBT,
	SYS_DSS,
	SYS_DVBS,
	SYS_DVBS2,
	SYS_DVBH,
	SYS_ISDBT,
	SYS_ISDBS,
	SYS_ISDBC,
	SYS_ATSC,
	SYS_ATSCMH,
	SYS_DMBTH,
	SYS_CMMB,
	SYS_DAB,
	SYS_DVBT2,
	SYS_TURBO,
	SYS_DVBC_ANNEX_C,
} fe_delivery_system_t;

DTV_ISDBT_PARTIAL_RECEPTION

If DTV_ISDBT_SOUND_BROADCASTING is '0' this bit-field represents whether the channel is in partial reception mode or not.

If '1' DTV_ISDBT_LAYERA_* values are assigned to the center segment and DTV_ISDBT_LAYERA_SEGMENT_COUNT has to be '1'.

If in addition DTV_ISDBT_SOUND_BROADCASTING is '1' DTV_ISDBT_PARTIAL_RECEPTION represents whether this ISDB-Tsb channel is consisting of one segment and layer or three segments and two layers.

Possible values: 0, 1, -1 (AUTO)

DTV_ISDBT_SOUND_BROADCASTING

This field represents whether the other DTV_ISDBT_*-parameters are referring to an ISDB-T and an ISDB-Tsb channel. (See also DTV_ISDBT_PARTIAL_RECEPTION).

Possible values: 0, 1, -1 (AUTO)

DTV_ISDBT_SB_SUBCHANNEL_ID

This field only applies if DTV_ISDBT_SOUND_BROADCASTING is '1'.

(Note of the author: This might not be the correct description of the SUBCHANNEL-ID in all details, but it is my understanding of the technical background needed to program a device)

An ISDB-Tsb channel (1 or 3 segments) can be broadcasted alone or in a set of connected ISDB-Tsb channels. In this set of channels every channel can be received independently. The number of connected ISDB-Tsb segment can vary, e.g. depending on the frequency spectrum bandwidth available.

Example: Assume 8 ISDB-Tsb connected segments are broadcasted. The broadcaster has several possibilities to put those channels in the air: Assuming a normal 13-segment ISDB-T spectrum he can align the 8 segments from position 1-8 to 5-13 or anything in between.

The underlying layer of segments are subchannels: each segment is consisting of several subchannels with a predefined IDs. A sub-channel is used to help the demodulator to synchronize on the channel.

An ISDB-T channel is always centered over all sub-channels. As for the example above, in ISDB-Tsb it is no longer as simple as that.

The DTV_ISDBT_SB_SUBCHANNEL_ID parameter is used to give the sub-channel ID of the segment to be demodulated.

Possible values: 0 .. 41, -1 (AUTO)

DTV_ISDBT_SB_SEGMENT_IDX

This field only applies if DTV_ISDBT_SOUND_BROADCASTING is '1'.

DTV_ISDBT_SB_SEGMENT_IDX gives the index of the segment to be demodulated for an ISDB-Tsb channel where several of them are transmitted in the connected manner.

Possible values: 0 .. DTV_ISDBT_SB_SEGMENT_COUNT - 1

Note: This value cannot be determined by an automatic channel search.

DTV_ISDBT_SB_SEGMENT_COUNT

This field only applies if DTV_ISDBT_SOUND_BROADCASTING is '1'.

DTV_ISDBT_SB_SEGMENT_COUNT gives the total count of connected ISDB-Tsb channels.

Possible values: 1 .. 13

Note: This value cannot be determined by an automatic channel search.

DTV-ISDBT-LAYER* parameters

ISDB-T channels can be coded hierarchically. As opposed to DVB-T in ISDB-T hierarchical layers can be decoded simultaneously. For that reason a ISDB-T demodulator has 3 viterbi and 3 reed-solomon-decoders.

ISDB-T has 3 hierarchical layers which each can use a part of the available segments. The total number of segments over all layers has to 13 in ISDB-T.

There are 3 parameter sets, for Layers A, B and C.

DTV_ISDBT_LAYER_ENABLED

Hierarchical reception in ISDB-T is achieved by enabling or disabling layers in the decoding process. Setting all bits of DTV_ISDBT_LAYER_ENABLED to '1' forces all layers (if applicable) to be demodulated. This is the default.

If the channel is in the partial reception mode (DTV_ISDBT_PARTIAL_RECEPTION = 1) the central segment can be decoded independently of the other 12 segments. In that mode layer A has to have a SEGMENT_COUNT of 1.

In ISDB-Tsb only layer A is used, it can be 1 or 3 in ISDB-Tsb according to DTV_ISDBT_PARTIAL_RECEPTION. SEGMENT_COUNT must be filled accordingly.

Possible values: 0x1, 0x2, 0x4 (|-able)

DTV_ISDBT_LAYER_ENABLED[0:0] - layer A

DTV_ISDBT_LAYER_ENABLED[1:1] - layer B

DTV_ISDBT_LAYER_ENABLED[2:2] - layer C

DTV_ISDBT_LAYER_ENABLED[31:3] unused

DTV_ISDBT_LAYER*_FEC

Possible values: FEC_AUTO, FEC_1_2, FEC_2_3, FEC_3_4, FEC_5_6, FEC_7_8

DTV_ISDBT_LAYER*_MODULATION

Possible values: QAM_AUTO, QPSK, QAM_16, QAM_64, DQPSK

Note: If layer C is DQPSK layer B has to be DQPSK. If layer B is DQPSK and DTV_ISDBT_PARTIAL_RECEPTION=0 layer has to be DQPSK.

DTV_ISDBT_LAYER*_SEGMENT_COUNT

Possible values: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, -1 (AUTO)

Note: Truth table for DTV_ISDBT_SOUND_BROADCASTING and DTV_ISDBT_PARTIAL_RECEPTION and LAYER*_SEGMENT_COUNT

PRSBLayer A widthLayer B widthLayer C widthtotal width
001 .. 131 .. 131 .. 1313
1011 .. 131 .. 1313
011001
1112013
DTV_ISDBT_LAYER*_TIME_INTERLEAVING

Possible values: 0, 1, 2, 3, -1 (AUTO)

Note: The real inter-leaver depth-names depend on the mode (fft-size); the values here are referring to what can be found in the TMCC-structure - independent of the mode.

DTV_API_VERSION

Returns the major/minor version of the DVB API

DTV_CODE_RATE_HP

Used on terrestrial transmissions. The acceptable values are:

typedef enum fe_code_rate {
	FEC_NONE = 0,
	FEC_1_2,
	FEC_2_3,
	FEC_3_4,
	FEC_4_5,
	FEC_5_6,
	FEC_6_7,
	FEC_7_8,
	FEC_8_9,
	FEC_AUTO,
	FEC_3_5,
	FEC_9_10,
} fe_code_rate_t;
	

DTV_CODE_RATE_LP

Used on terrestrial transmissions. The acceptable values are:

typedef enum fe_code_rate {
	FEC_NONE = 0,
	FEC_1_2,
	FEC_2_3,
	FEC_3_4,
	FEC_4_5,
	FEC_5_6,
	FEC_6_7,
	FEC_7_8,
	FEC_8_9,
	FEC_AUTO,
	FEC_3_5,
	FEC_9_10,
} fe_code_rate_t;
	

DTV_GUARD_INTERVAL

Possible values are:

typedef enum fe_guard_interval {
	GUARD_INTERVAL_1_32,
	GUARD_INTERVAL_1_16,
	GUARD_INTERVAL_1_8,
	GUARD_INTERVAL_1_4,
	GUARD_INTERVAL_AUTO,
	GUARD_INTERVAL_1_128,
	GUARD_INTERVAL_19_128,
	GUARD_INTERVAL_19_256,
} fe_guard_interval_t;

Notes:

1) If DTV_GUARD_INTERVAL is set the GUARD_INTERVAL_AUTO the hardware will try to find the correct guard interval (if capable) and will use TMCC to fill in the missing parameters.

2) Intervals 1/128, 19/128 and 19/256 are used only for DVB-T2 at present

DTV_TRANSMISSION_MODE

Specifies the number of carriers used by the standard

Possible values are:

typedef enum fe_transmit_mode {
	TRANSMISSION_MODE_2K,
	TRANSMISSION_MODE_8K,
	TRANSMISSION_MODE_AUTO,
	TRANSMISSION_MODE_4K,
	TRANSMISSION_MODE_1K,
	TRANSMISSION_MODE_16K,
	TRANSMISSION_MODE_32K,
} fe_transmit_mode_t;

Notes:

1) ISDB-T supports three carrier/symbol-size: 8K, 4K, 2K. It is called 'mode' in the standard: Mode 1 is 2K, mode 2 is 4K, mode 3 is 8K

2) If DTV_TRANSMISSION_MODE is set the TRANSMISSION_MODE_AUTO the hardware will try to find the correct FFT-size (if capable) and will use TMCC to fill in the missing parameters.

3) DVB-T specifies 2K and 8K as valid sizes.

4) DVB-T2 specifies 1K, 2K, 4K, 8K, 16K and 32K.

DTV_HIERARCHY

Frontend hierarchy

typedef enum fe_hierarchy {
	 HIERARCHY_NONE,
	 HIERARCHY_1,
	 HIERARCHY_2,
	 HIERARCHY_4,
	 HIERARCHY_AUTO
 } fe_hierarchy_t;
	

DTV_ISDBS_TS_ID

Currently unused.

DTV_DVBT2_PLP_ID

DVB-T2 supports Physical Layer Pipes (PLP) to allow transmission of many data types via a single multiplex. The API will soon support this at which point this section will be expanded.

DTV_ENUM_DELSYS

A Multi standard frontend needs to advertise the delivery systems provided. Applications need to enumerate the provided delivery systems, before using any other operation with the frontend. Prior to it's introduction, FE_GET_INFO was used to determine a frontend type. A frontend which provides more than a single delivery system, FE_GET_INFO doesn't help much. Applications which intends to use a multistandard frontend must enumerate the delivery systems associated with it, rather than trying to use FE_GET_INFO. In the case of a legacy frontend, the result is just the same as with FE_GET_INFO, but in a more structured format

Properties used on terrestrial delivery systems

DVB-T2 delivery system

DVB-T2 support is currently in the early stages of development, so expect that this section maygrow and become more detailed with time.

The following parameters are valid for DVB-T2:

ISDB-T delivery system

This ISDB-T/ISDB-Tsb API extension should reflect all information needed to tune any ISDB-T/ISDB-Tsb hardware. Of course it is possible that some very sophisticated devices won't need certain parameters to tune.

The information given here should help application writers to know how to handle ISDB-T and ISDB-Tsb hardware using the Linux DVB-API.

The details given here about ISDB-T and ISDB-Tsb are just enough to basically show the dependencies between the needed parameter values, but surely some information is left out. For more detailed information see the following documents:

ARIB STD-B31 - "Transmission System for Digital Terrestrial Television Broadcasting" and

ARIB TR-B14 - "Operational Guidelines for Digital Terrestrial Television Broadcasting".

In order to understand the ISDB specific parameters, one has to have some knowledge the channel structure in ISDB-T and ISDB-Tsb. I.e. it has to be known to the reader that an ISDB-T channel consists of 13 segments, that it can have up to 3 layer sharing those segments, and things like that.

The following parameters are valid for ISDB-T:

ATSC delivery system

The following parameters are valid for ATSC:

Properties used on cable delivery systems

DVB-C delivery system

The DVB-C Annex-A is the widely used cable standard. Transmission uses QAM modulation.

The DVB-C Annex-C is optimized for 6MHz, and is used in Japan. It supports a subset of the Annex A modulation types, and a roll-off of 0.13, instead of 0.15

The following parameters are valid for DVB-C Annex A/C:

DVB-C Annex B delivery system

The DVB-C Annex-B is only used on a few Countries like the United States.

The following parameters are valid for DVB-C Annex B:

Properties used on satellital delivery systems

DVB-S delivery system

The following parameters are valid for DVB-S:

Future implementations might add those two missing parameters:

DVB-S2 delivery system

In addition to all parameters valid for DVB-S, DVB-S2 supports the following parameters:

Turbo code delivery system

In addition to all parameters valid for DVB-S, turbo code supports the following parameters: