# `FE_GET_PROPERTY/FE_SET_PROPERTY`

This section describes the DVB version 5 extension 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 stats type

    struct dtv_stats {
    	__u8 scale;	/* enum fecap_scale_params type */
    	union {
    		__u64 uvalue;	/* for counters and relative scales */
    		__s64 svalue;	/* for 1/1000 dB measures */
    	};
    } __packed;

## DTV stats type

    #define MAX_DTV_STATS   4

    struct dtv_fe_stats {
    	__u8 len;
    	struct dtv_stats stat[MAX_DTV_STATS];
    } __packed;

## DTV property type

    /* Reserved fields should be set to 0 */

    struct dtv_property {
    	__u32 cmd;
    	__u32 reserved[3];
    	union {
    		__u32 data;
    		struct dtv_fe_stats st;
    		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-dvb;

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-dvb;

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 frequency 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,
    	QAM_4_NR,
     } 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,
    	FEC_2_5,
    } 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_DTMB,
    	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`, QP`SK, 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

PR | SB | Layer A width | Layer B width | Layer C width | total width
0 | 0 | 1 .. 13 | 1 .. 13 | 1 .. 13 | 13
1 | 0 | 1 | 1 .. 13 | 1 .. 13 | 13
0 | 1 | 1 | 0 | 0 | 1
1 | 1 | 1 | 2 | 0 | 13

#### `DTV_ISDBT_LAYER*_TIME_INTERLEAVING`

Valid values: 0, 1, 2, 4, -1 (AUTO)

when DTV_ISDBT_SOUND_BROADCASTING is active, value 8 is also valid.

Note: The real time interleaving length depends on the mode (fft-size). The values here are referring to what can be found in the TMCC-structure, as shown in the table below.

DTV_ISDBT_LAYER*_TIME_INTERLEAVING | Mode 1 (2K FFT) | Mode 2 (4K FFT) | Mode 3 (8K FFT)
0 | 0 | 0 | 0
1 | 4 | 2 | 1
2 | 8 | 4 | 2
4 | 16 | 8 | 4

#### `DTV_ATSCMH_FIC_VER`

Version number of the FIC (Fast Information Channel) signaling data.

FIC is used for relaying information to allow rapid service acquisition by the receiver.

Possible values: 0, 1, 2, 3, ..., 30, 31

#### `DTV_ATSCMH_PARADE_ID`

Parade identification number

A parade is a collection of up to eight MH groups, conveying one or two ensembles.

Possible values: 0, 1, 2, 3, ..., 126, 127

#### `DTV_ATSCMH_NOG`

Number of MH groups per MH subframe for a designated parade.

Possible values: 1, 2, 3, 4, 5, 6, 7, 8

#### `DTV_ATSCMH_TNOG`

Total number of MH groups including all MH groups belonging to all MH parades in one MH subframe.

Possible values: 0, 1, 2, 3, ..., 30, 31

#### `DTV_ATSCMH_SGN`

Start group number.

Possible values: 0, 1, 2, 3, ..., 14, 15

#### `DTV_ATSCMH_PRC`

Parade repetition cycle.

Possible values: 1, 2, 3, 4, 5, 6, 7, 8

#### `DTV_ATSCMH_RS_FRAME_MODE`

RS frame mode.

Possible values are:

    typedef enum atscmh_rs_frame_mode {
    	ATSCMH_RSFRAME_PRI_ONLY  = 0,
    	ATSCMH_RSFRAME_PRI_SEC   = 1,
    } atscmh_rs_frame_mode_t;

#### `DTV_ATSCMH_RS_FRAME_ENSEMBLE`

RS frame ensemble.

Possible values are:

    typedef enum atscmh_rs_frame_ensemble {
    	ATSCMH_RSFRAME_ENS_PRI   = 0,
    	ATSCMH_RSFRAME_ENS_SEC   = 1,
    } atscmh_rs_frame_ensemble_t;

#### `DTV_ATSCMH_RS_CODE_MODE_PRI`

RS code mode (primary).

Possible values are:

    typedef enum atscmh_rs_code_mode {
    	ATSCMH_RSCODE_211_187    = 0,
    	ATSCMH_RSCODE_223_187    = 1,
    	ATSCMH_RSCODE_235_187    = 2,
    } atscmh_rs_code_mode_t;

#### `DTV_ATSCMH_RS_CODE_MODE_SEC`

RS code mode (secondary).

Possible values are:

    typedef enum atscmh_rs_code_mode {
    	ATSCMH_RSCODE_211_187    = 0,
    	ATSCMH_RSCODE_223_187    = 1,
    	ATSCMH_RSCODE_235_187    = 2,
    } atscmh_rs_code_mode_t;

#### `DTV_ATSCMH_SCCC_BLOCK_MODE`

Series Concatenated Convolutional Code Block Mode.

Possible values are:

    typedef enum atscmh_sccc_block_mode {
    	ATSCMH_SCCC_BLK_SEP      = 0,
    	ATSCMH_SCCC_BLK_COMB     = 1,
    } atscmh_sccc_block_mode_t;

#### `DTV_ATSCMH_SCCC_CODE_MODE_A`

Series Concatenated Convolutional Code Rate.

Possible values are:

    typedef enum atscmh_sccc_code_mode {
    	ATSCMH_SCCC_CODE_HLF     = 0,
    	ATSCMH_SCCC_CODE_QTR     = 1,
    } atscmh_sccc_code_mode_t;

#### `DTV_ATSCMH_SCCC_CODE_MODE_B`

Series Concatenated Convolutional Code Rate.

Possible values are:

    typedef enum atscmh_sccc_code_mode {
    	ATSCMH_SCCC_CODE_HLF     = 0,
    	ATSCMH_SCCC_CODE_QTR     = 1,
    } atscmh_sccc_code_mode_t;

#### `DTV_ATSCMH_SCCC_CODE_MODE_C`

Series Concatenated Convolutional Code Rate.

Possible values are:

    typedef enum atscmh_sccc_code_mode {
    	ATSCMH_SCCC_CODE_HLF     = 0,
    	ATSCMH_SCCC_CODE_QTR     = 1,
    } atscmh_sccc_code_mode_t;

#### `DTV_ATSCMH_SCCC_CODE_MODE_D`

Series Concatenated Convolutional Code Rate.

Possible values are:

    typedef enum atscmh_sccc_code_mode {
    	ATSCMH_SCCC_CODE_HLF     = 0,
    	ATSCMH_SCCC_CODE_QTR     = 1,
    } atscmh_sccc_code_mode_t;

### `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,
    	GUARD_INTERVAL_PN420,
    	GUARD_INTERVAL_PN595,
    	GUARD_INTERVAL_PN945,
    } 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

3) DTMB specifies PN420, PN595 and PN945.

### `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,
    	TRANSMISSION_MODE_C1,
    	TRANSMISSION_MODE_C3780,
    } 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.

5) DTMB specifies C1 and C3780.

### `DTV_HIERARCHY`

Frontend hierarchy

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

### `DTV_STREAM_ID`

DVB-S2, DVB-T2 and ISDB-S support the transmission of several streams on a single transport stream. This property enables the DVB driver to handle substream filtering, when supported by the hardware. By default, substream filtering is disabled.

For DVB-S2 and DVB-T2, the valid substream id range is from 0 to 255.

For ISDB, the valid substream id range is from 1 to 65535.

To disable it, you should use the special macro NO_STREAM_ID_FILTER.

Note: any value outside the id range also disables filtering.

### `DTV_DVBT2_PLP_ID_LEGACY`

Obsolete, replaced with DTV_STREAM_ID.

### `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

### `DTV_INTERLEAVING`

Interleaving mode

    enum fe_interleaving {
    	INTERLEAVING_NONE,
    	INTERLEAVING_AUTO,
    	INTERLEAVING_240,
    	INTERLEAVING_720,
    };

### `DTV_LNA`

Low-noise amplifier.

Hardware might offer controllable LNA which can be set manually using that parameter. Usually LNA could be found only from terrestrial devices if at all.

Possible values: 0, 1, LNA_AUTO

0, LNA off

1, LNA on

use the special macro LNA_AUTO to set LNA auto

## Frontend statistics indicators

The values are returned via `dtv_property.stat`. If the property is supported, `dtv_property.stat.len` is bigger than zero.

For most delivery systems, `dtv_property.stat.len` will be 1 if the stats is supported, and the properties will return a single value for each parameter.

It should be noticed, however, that new OFDM delivery systems like ISDB can use different modulation types for each group of carriers. On such standards, up to 3 groups of statistics can be provided, and `dtv_property.stat.len` is updated to reflect the "global" metrics, plus one metric per each carrier group (called "layer" on ISDB).

So, in order to be consistent with other delivery systems, the first value at `dtv_property.stat.dtv_stats` array refers to the global metric. The other elements of the array represent each layer, starting from layer A(index 1), layer B (index 2) and so on.

The number of filled elements are stored at `dtv_property.stat.len`.

Each element of the `dtv_property.stat.dtv_stats` array consists on two elements:

- `svalue` or `uvalue`, where `svalue` is for signed values of the measure (dB measures) and `uvalue` is for unsigned values (counters, relative scale)

- `scale` - Scale for the value. It can be:

  - `FE_SCALE_NOT_AVAILABLE` - The parameter is supported by the frontend, but it was not possible to collect it (could be a transitory or permanent condition)

  - `FE_SCALE_DECIBEL` - parameter is a signed value, measured in 1/1000 dB

  - `FE_SCALE_RELATIVE` - parameter is a unsigned value, where 0 means 0% and 65535 means 100%.

  - `FE_SCALE_COUNTER` - parameter is a unsigned value that counts the occurrence of an event, like bit error, block error, or lapsed time.

### `DTV_STAT_SIGNAL_STRENGTH`

Indicates the signal strength level at the analog part of the tuner or of the demod.

Possible scales for this metric are:

- `FE_SCALE_NOT_AVAILABLE` - it failed to measure it, or the measurement was not complete yet.

- `FE_SCALE_DECIBEL` - signal strength is in 0.0001 dBm units, power measured in miliwatts. This value is generally negative.

- `FE_SCALE_RELATIVE` - The frontend provides a 0% to 100% measurement for power (actually, 0 to 65535).

### `DTV_STAT_CNR`

Indicates the Signal to Noise ratio for the main carrier.

Possible scales for this metric are:

- `FE_SCALE_NOT_AVAILABLE` - it failed to measure it, or the measurement was not complete yet.

- `FE_SCALE_DECIBEL` - Signal/Noise ratio is in 0.0001 dB units.

- `FE_SCALE_RELATIVE` - The frontend provides a 0% to 100% measurement for Signal/Noise (actually, 0 to 65535).

### `DTV_STAT_PRE_ERROR_BIT_COUNT`

Measures the number of bit errors before the forward error correction (FEC) on the inner coding block (before Viterbi, LDPC or other inner code).

This measure is taken during the same interval as `DTV_STAT_PRE_TOTAL_BIT_COUNT`.

In order to get the BER (Bit Error Rate) measurement, it should be divided by `DTV_STAT_PRE_TOTAL_BIT_COUNT`.

This measurement is monotonically increased, as the frontend gets more bit count measurements. The frontend may reset it when a channel/transponder is tuned.

Possible scales for this metric are:

- `FE_SCALE_NOT_AVAILABLE` - it failed to measure it, or the measurement was not complete yet.

- `FE_SCALE_COUNTER` - Number of error bits counted before the inner coding.

### `DTV_STAT_PRE_TOTAL_BIT_COUNT`

Measures the amount of bits received before the inner code block, during the same period as `DTV_STAT_PRE_ERROR_BIT_COUNT` measurement was taken.

It should be noticed that this measurement can be smaller than the total amount of bits on the transport stream, as the frontend may need to manually restart the measurement, losing some data between each measurement interval.

This measurement is monotonically increased, as the frontend gets more bit count measurements. The frontend may reset it when a channel/transponder is tuned.

Possible scales for this metric are:

- `FE_SCALE_NOT_AVAILABLE` - it failed to measure it, or the measurement was not complete yet.

- `FE_SCALE_COUNTER` - Number of bits counted while measuring `DTV_STAT_PRE_ERROR_BIT_COUNT`.

### `DTV_STAT_POST_ERROR_BIT_COUNT`

Measures the number of bit errors after the forward error correction (FEC) done by inner code block (after Viterbi, LDPC or other inner code).

This measure is taken during the same interval as `DTV_STAT_POST_TOTAL_BIT_COUNT`.

In order to get the BER (Bit Error Rate) measurement, it should be divided by `DTV_STAT_POST_TOTAL_BIT_COUNT`.

This measurement is monotonically increased, as the frontend gets more bit count measurements. The frontend may reset it when a channel/transponder is tuned.

Possible scales for this metric are:

- `FE_SCALE_NOT_AVAILABLE` - it failed to measure it, or the measurement was not complete yet.

- `FE_SCALE_COUNTER` - Number of error bits counted after the inner coding.

### `DTV_STAT_POST_TOTAL_BIT_COUNT`

Measures the amount of bits received after the inner coding, during the same period as `DTV_STAT_POST_ERROR_BIT_COUNT` measurement was taken.

It should be noticed that this measurement can be smaller than the total amount of bits on the transport stream, as the frontend may need to manually restart the measurement, losing some data between each measurement interval.

This measurement is monotonically increased, as the frontend gets more bit count measurements. The frontend may reset it when a channel/transponder is tuned.

Possible scales for this metric are:

- `FE_SCALE_NOT_AVAILABLE` - it failed to measure it, or the measurement was not complete yet.

- `FE_SCALE_COUNTER` - Number of bits counted while measuring `DTV_STAT_POST_ERROR_BIT_COUNT`.

### `DTV_STAT_ERROR_BLOCK_COUNT`

Measures the number of block errors after the outer forward error correction coding (after Reed-Solomon or other outer code).

This measurement is monotonically increased, as the frontend gets more bit count measurements. The frontend may reset it when a channel/transponder is tuned.

Possible scales for this metric are:

- `FE_SCALE_NOT_AVAILABLE` - it failed to measure it, or the measurement was not complete yet.

- `FE_SCALE_COUNTER` - Number of error blocks counted after the outer coding.

### `DTV-STAT_TOTAL_BLOCK_COUNT`

Measures the total number of blocks received during the same period as `DTV_STAT_ERROR_BLOCK_COUNT` measurement was taken.

It can be used to calculate the PER indicator, by dividing `DTV_STAT_ERROR_BLOCK_COUNT` by `DTV-STAT-TOTAL-BLOCK-COUNT`.

Possible scales for this metric are:

- `FE_SCALE_NOT_AVAILABLE` - it failed to measure it, or the measurement was not complete yet.

- `FE_SCALE_COUNTER` - Number of blocks counted while measuring `DTV_STAT_ERROR_BLOCK_COUNT`.

## Properties used on terrestrial delivery systems

### DVB-T delivery system

The following parameters are valid for DVB-T:

- `DTV_API_VERSION`

- `DTV_DELIVERY_SYSTEM`

- `DTV_TUNE`

- `DTV_CLEAR`

- `DTV_FREQUENCY`

- `DTV_MODULATION`

- `DTV_BANDWIDTH_HZ`

- `DTV_INVERSION`

- `DTV_CODE_RATE_HP`

- `DTV_CODE_RATE_LP`

- `DTV_GUARD_INTERVAL`

- `DTV_TRANSMISSION_MODE`

- `DTV_HIERARCHY`

- `DTV_LNA`

In addition, the DTV QoS statistics are also valid.

### 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:

- `DTV_API_VERSION`

- `DTV_DELIVERY_SYSTEM`

- `DTV_TUNE`

- `DTV_CLEAR`

- `DTV_FREQUENCY`

- `DTV_MODULATION`

- `DTV_BANDWIDTH_HZ`

- `DTV_INVERSION`

- `DTV_CODE_RATE_HP`

- `DTV_CODE_RATE_LP`

- `DTV_GUARD_INTERVAL`

- `DTV_TRANSMISSION_MODE`

- `DTV_HIERARCHY`

- `DTV_STREAM_ID`

- `DTV_LNA`

In addition, the DTV QoS statistics are also valid.

### 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:

- `DTV_API_VERSION`

- `DTV_DELIVERY_SYSTEM`

- `DTV_TUNE`

- `DTV_CLEAR`

- `DTV_FREQUENCY`

- `DTV_BANDWIDTH_HZ`

- `DTV_INVERSION`

- `DTV_GUARD_INTERVAL`

- `DTV_TRANSMISSION_MODE`

- `DTV_ISDBT_LAYER_ENABLED`

- `DTV_ISDBT_PARTIAL_RECEPTION`

- `DTV_ISDBT_SOUND_BROADCASTING`

- `DTV_ISDBT_SB_SUBCHANNEL_ID`

- `DTV_ISDBT_SB_SEGMENT_IDX`

- `DTV_ISDBT_SB_SEGMENT_COUNT`

- `DTV_ISDBT_LAYERA_FEC`

- `DTV_ISDBT_LAYERA_MODULATION`

- `DTV_ISDBT_LAYERA_SEGMENT_COUNT`

- `DTV_ISDBT_LAYERA_TIME_INTERLEAVING`

- `DTV_ISDBT_LAYERB_FEC`

- `DTV_ISDBT_LAYERB_MODULATION`

- `DTV_ISDBT_LAYERB_SEGMENT_COUNT`

- `DTV_ISDBT_LAYERB_TIME_INTERLEAVING`

- `DTV_ISDBT_LAYERC_FEC`

- `DTV_ISDBT_LAYERC_MODULATION`

- `DTV_ISDBT_LAYERC_SEGMENT_COUNT`

- `DTV_ISDBT_LAYERC_TIME_INTERLEAVING`

In addition, the DTV QoS statistics are also valid.

### ATSC delivery system

The following parameters are valid for ATSC:

- `DTV_API_VERSION`

- `DTV_DELIVERY_SYSTEM`

- `DTV_TUNE`

- `DTV_CLEAR`

- `DTV_FREQUENCY`

- `DTV_MODULATION`

- `DTV_BANDWIDTH_HZ`

In addition, the DTV QoS statistics are also valid.

### ATSC-MH delivery system

The following parameters are valid for ATSC-MH:

- `DTV_API_VERSION`

- `DTV_DELIVERY_SYSTEM`

- `DTV_TUNE`

- `DTV_CLEAR`

- `DTV_FREQUENCY`

- `DTV_BANDWIDTH_HZ`

- `DTV_ATSCMH_FIC_VER`

- `DTV_ATSCMH_PARADE_ID`

- `DTV_ATSCMH_NOG`

- `DTV_ATSCMH_TNOG`

- `DTV_ATSCMH_SGN`

- `DTV_ATSCMH_PRC`

- `DTV_ATSCMH_RS_FRAME_MODE`

- `DTV_ATSCMH_RS_FRAME_ENSEMBLE`

- `DTV_ATSCMH_RS_CODE_MODE_PRI`

- `DTV_ATSCMH_RS_CODE_MODE_SEC`

- `DTV_ATSCMH_SCCC_BLOCK_MODE`

- `DTV_ATSCMH_SCCC_CODE_MODE_A`

- `DTV_ATSCMH_SCCC_CODE_MODE_B`

- `DTV_ATSCMH_SCCC_CODE_MODE_C`

- `DTV_ATSCMH_SCCC_CODE_MODE_D`

In addition, the DTV QoS statistics are also valid.

### DTMB delivery system

The following parameters are valid for DTMB:

- `DTV_API_VERSION`

- `DTV_DELIVERY_SYSTEM`

- `DTV_TUNE`

- `DTV_CLEAR`

- `DTV_FREQUENCY`

- `DTV_MODULATION`

- `DTV_BANDWIDTH_HZ`

- `DTV_INVERSION`

- `DTV_INNER_FEC`

- `DTV_GUARD_INTERVAL`

- `DTV_TRANSMISSION_MODE`

- `DTV_INTERLEAVING`

- `DTV_LNA`

In addition, the DTV QoS statistics are also valid.

## 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:

- `DTV_API_VERSION`

- `DTV_DELIVERY_SYSTEM`

- `DTV_TUNE`

- `DTV_CLEAR`

- `DTV_FREQUENCY`

- `DTV_MODULATION`

- `DTV_INVERSION`

- `DTV_SYMBOL_RATE`

- `DTV_INNER_FEC`

- `DTV_LNA`

In addition, the DTV QoS statistics are also valid.

### 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:

- `DTV_API_VERSION`

- `DTV_DELIVERY_SYSTEM`

- `DTV_TUNE`

- `DTV_CLEAR`

- `DTV_FREQUENCY`

- `DTV_MODULATION`

- `DTV_INVERSION`

- `DTV_LNA`

In addition, the DTV QoS statistics are also valid.

## Properties used on satellital delivery systems

### DVB-S delivery system

The following parameters are valid for DVB-S:

- `DTV_API_VERSION`

- `DTV_DELIVERY_SYSTEM`

- `DTV_TUNE`

- `DTV_CLEAR`

- `DTV_FREQUENCY`

- `DTV_INVERSION`

- `DTV_SYMBOL_RATE`

- `DTV_INNER_FEC`

- `DTV_VOLTAGE`

- `DTV_TONE`

In addition, the DTV QoS statistics are also valid.

Future implementations might add those two missing parameters:

- `DTV_DISEQC_MASTER`

- `DTV_DISEQC_SLAVE_REPLY`

### DVB-S2 delivery system

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

- `DTV_MODULATION`

- `DTV_PILOT`

- `DTV_ROLLOFF`

- `DTV_STREAM_ID`

In addition, the DTV QoS statistics are also valid.

### Turbo code delivery system

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

- `DTV_MODULATION`

### ISDB-S delivery system

The following parameters are valid for ISDB-S:

- `DTV_API_VERSION`

- `DTV_DELIVERY_SYSTEM`

- `DTV_TUNE`

- `DTV_CLEAR`

- `DTV_FREQUENCY`

- `DTV_INVERSION`

- `DTV_SYMBOL_RATE`

- `DTV_INNER_FEC`

- `DTV_VOLTAGE`

- `DTV_STREAM_ID`