Main Content

VITA 49 Packet Format

Versa Module Eurocard (VME) bus International Trade Association (VITA) 49 file reader reads the signal data packet and context data packet as structures. These structures are returned as an output by the read object function of the vita49Reader object.

Signal Data Packet

Signal data packets convey digitized intermediate frequency (IF) and radio frequency (RF) signals. The output structure of the decoded signal data packet of read object function contains these fields.

Field DescriptionValue
PacketType

Type of VITA 49 packet, returned as one of these values.

  • 0, 1, 2, or 3 — Indicates signal time data packet

  • 4 or 5 — Indicates context packet

Integer in the range [0, 5]
StreamID

Stream ID, as specified by the name-value argument StreamID, of the read object function.

32-bit unsigned integer
ClassID

Class ID, as specified by the name-value argument ClassID, of the read object function.

Character vector or string scalar
PadBitCountPad bit count represents the difference between the nearest multiple of 32 and the actual number of payload bits to pack, returned as a nonnegative integer. Pad bits are required when the size and the number of data items do not completely fill the last 32-bit word of a data packet.8-bit unsigned integer
IntegerTimestampType

Integer timestamp type, returned as "UTC", "GPS", or a user-specified time-code.

Character vector or string scalar
IntegerTimestampValue

Integer timestamp value, in seconds. This value represents the reference point time of the data samples or metadata in the packet, returned to 1-second resolution accuracy.

32-bit unsigned integer
FractionalTimestampType

Fractional timestamp, returned as "sample count", "real time", or "free running count".

When this value is "sample count" or "real time", the FractionalTimestampValue value adds resolution to the IntegerTimestampValue value, so that together they provide a range of years, and a precision down to sample period or picoseconds, respectively. When returned as "free running count", the value provides an incrementing sample count from any chosen starting time.

Character vector or string scalar
FractionalTimestampValue

Fractional timestamp value in picoseconds, represents the reference point time of the data samples or metadata in the packet, returned as a timestamp of higher resolution than the integer timestamp value.

64-bit unsigned integer
RawBytes

Raw payload in bytes, which is not decoded, returned as a column vector.

Column vector with 8-bit unsigned integer elements
IQSamples

Decoded real or complex in-phase quadrature (IQ) Cartesian samples of the signal data, returned as a column vector.

This function does not support decoding of complex polar samples.

Column vector with elements of data type double
Trailer

Validity of the decoded data and the status of the processes producing that data, returned as a structure with these fields.

FieldDescription
CalibratedTimeIndicator

Calibrated time indicator, returned as one of these logical values.

  • 1 — Indicates the timestamp in the signal data packet is calibrated to some external reference

  • 0 — Indicates the timestamp is free running and may be inaccurate

ValidDataIndicator

Valid data indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates the data packet as valid.

ReferenceLockIndicator

Reference lock indicator, returned as one of these logical values.

  • 1 — Indicates any phase-locked loops (PLL) affecting the data are locked and stable

  • 0 — Indicates at least one PLL is not locked and stable

AGCIndicator

AGC indicator, returned as one of these logical values.

  • 1 — Indicates AGC is active

  • 0 — Indicates MGC is active

MGCIndicator

MGC indicator, returned as one of these logical values.

  • 1 — Indicates MGC is active

  • 0 — Indicates AGC is active

DetectedSignalIndicator

Detected signal indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates that the data contained in the packet has some detected signal.

SpectrumInversionIndicator

Spectrum inversion indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates that the signal conveyed in the data payload has an inverted spectrum with respect to the spectrum of the signal at the system reference point.

OverRangeIndicator

Over range indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates that at least one data sample in the payload is invalid due to the signal exceeding the range of the data item.

SampleLossIndicator

Sample loss indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates that the packet contains at least one sample discontinuity due to processing errors or buffer overflow.

AssociatedContextPacketCount

Associated context packet count, returned as a 7-bit unsigned integer. This count includes the associated context packets transmitted by a process other than the one that transmits the signal data packet containing the count.

Structure

Context Packet

Context packets convey information such as the sample rate of the data, the frequency range being transmitted, and the type of modulation used. It also conveys transmit control information that allows the receiver to dynamically adjust various parameters of the transmitted data, such as the gain or frequency offset, to optimize the reception quality to interpret and process the data accurately.

The output structure of the decoded context packet of read object function contains these fields.

Field DescriptionValue
PacketType

Type of VITA 49 packet, returned as one of these values.

  • 0, 1, 2, or 3 — Indicates signal time data packet

  • 4 or 5 — Indicates context packet

Integer in the range [0, 5]
StreamID

Stream ID, as specified by the name-value argument StreamID, of the read object function.

32-bit unsigned integer
ClassID

Class ID, as specified by the name-value argument ClassID, of the read object function.

Character vector or string scalar
IntegerTimestampType

Integer timestamp type, returned as "UTC", "GPS", or a user-specified time-code.

Character vector or string scalar
IntegerTimestampValue

Integer timestamp value, in seconds. This value represents the reference point time of the data samples or metadata in the packet, returned to 1-second resolution accuracy.

32-bit unsigned integer
FractionalTimestampType

Fractional timestamp, returned as "sample count", "real time", or "free running count".

When this value is "sample count" or "real time", the FractionalTimestampValue value adds resolution to the IntegerTimestampValue value, so that together they provide a range of years, and a precision down to sample period or picoseconds, respectively. When returned as "free running count", the value provides an incrementing sample count from any chosen starting time.

Character vector or string scalar
FractionalTimestampValue

Fractional timestamp value in picoseconds, represents the reference point time of data samples or metadata in the packet, returned as a timestamp of higher resolution than the integer timestamp value.

64-bit unsigned integer
RawBytes

Raw payload in bytes, which is not decoded, returned as a column vector.

Column vector with 8-bit unsigned integer elements
ContextFieldChangeIndicator

Bit indicator returned as 0 (false) or 1 (true). A value of 1 indicates that at least one context field contains a new value.

0 (false) or 1 (true)
ReferencePointIdentifier

Reference point ID consists of the StreamID of the reference point, returned as a nonnegative integer.

32-bit unsigned integer
Bandwidth

Usable spectrum at the output of a communication channel, returned as a nonnegative scalar in hertz.

Nonnegative scalar
IFReferenceFrequency

IF at which a carrier wave shifts as an intermediate step in transmission or reception of the signal, returned as a real scalar in hertz.

Real scalar
RFFrequency

Location in the signal path that corresponds to the original frequency, returned as a real scalar in hertz.

Real scalar
RFFrequencyOffset

Intentional slight deviation of the broadcast RF to reduce the interference with other transmitters, returned as a real scalar in hertz.

Real scalar
IFBandOffset

IF offset from the IFReferenceFrequency to the center of the band, returned as a real scalar in hertz.

Real scalar
ReferenceLevel

Physical signal amplitude at a reference point relative to the corresponding data sample value, returned as a real scalar in dB.

Real scalar
Gain

Amount of signal gain or signal attenuation from the reference point, returned as a real scalar in dB.

Real scalar
OverRangeCount

Number of data samples in the paired data packet whose amplitudes are beyond the range of the data item format, returned as a nonnegative integer in dB.

32-bit unsigned integer
SampleRate

Sampling rate of the data samples in the payload of a paired data packet stream, returned as a positive integer in hertz.

Positive integer
TimeStampAdjustment

Delay used to adjust the timestamp information of the first packet of the file, returned as a structure with these fields.

FieldDescription
GlobalTimestamp

Global timestamp indicator, returned as one of these logical values.

  • 1 — Indicates the timestamp details apply globally to all packets in the information stream

  • 0 — Indicates the timestamp details apply only to the context stream and the paired data stream

TSECode

Indicates the type of TimestampEpoch provided, returned as "Unspecified", "UTC", "GPS", or "POSIX".

TimestampEpoch

Conveys the time in one of these formats, depending on the value of the TSECode field.

  • If the TSECode field is returned as "UTC", then timestamp epoch conveys time in the UTC epoch. The value returned provides the time of the start of the epoch in international system of units (SI) seconds, including leap seconds, since 1970-01-01T00:00:00Z (UTC).

  • If the TSECode field is returned as "GPS", then timestamp epoch conveys time in the GPS epoch. The value returned provides the time of the start of the epoch used in SI seconds, since 1980-01-06T00:00:00Z (UTC). Leap seconds are not applicable within the GPS epoch.

  • If the TSECode field is returned as "POSIX", then timestamp epoch conveys time in the POSIX epoch. The value returned provides the time of the start of the epoch used in nominal seconds, since 1970-01-01T00:00:00Z (UTC). Leap seconds are not applicable within the POSIX epoch.

LeapSecondHandle

Indicates how the leap seconds are handled in the packet timestamps, returned as "Not applicable", "normal", "duplication", or "overflow".

SecScheduledPerDay

Indicates the number of seconds in the current day denoted by the packet timestamps, returned as 0, 86399, 86400, or 86401 seconds.

TimeSource

Indicates the time reference source used, returned as "Unspecified", "Atomic Clock", "Satellite System", "Terrestrial Radio", "PTP", "NTP or SNTP", or "Not Defined".

PosixTimebufferOffset

Conveys the difference in seconds between UTC time and POSIX time, returned as a 8-bit unsigned integer. This value represents the current total leap seconds count.

Structure
TimestampCalibrationTime

Conveys the date and time at which the timestamp in the data signal packet and context packet was confirmed accurate, returned as a nonnegative integer.

32-bit unsigned integer
StateAndEventIndicator

Conveys a set of binary indications and a limited number of non-binary state indications, returned as a structure with these fields.

This structure field is equivalent to be the Trailer field of the signalDataPacket output argument structure.

FieldDescription
CalibratedTimeIndicator

Calibrated time indicator, returned as one of these logical values.

  • 1 — Indicates the timestamp in the signal data packet is calibrated to some external reference

  • 0 — Indicates the timestamp is free running and may be inaccurate

ValidDataIndicator

Valid data indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates the data packet as valid.

ReferenceLockIndicator

Reference lock indicator, returned as one of these logical values.

  • 1 — Indicates any phase-locked loops (PLL) affecting the data are locked and stable

  • 0 — Indicates at least one PLL is not locked and stable

AGCIndicator

AGC indicator, returned as one of these logical values.

  • 1 — Indicates AGC is active

  • 0 — Indicates MGC is active

MGCIndicator

MGC indicator, returned as one of these logical values.

  • 1 — Indicates MGC is active

  • 0 — Indicates AGC is active

DetectedSignalIndicator

Detected signal indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates that the data contained in the packet has some detected signal.

SpectrumInversionIndicator

Spectrum inversion indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates that the signal conveyed in the data payload has an inverted spectrum with respect to the spectrum of the signal at the system Reference Point.

OverRangeIndicator

Over range indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates that at least one data sample in the payload is invalid due to the signal exceeding the range of the data item.

SampleLossIndicator

Sample loss indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates that the packet contains at least one sample discontinuity due to processing errors or buffer overflow.

AssociatedContextPacketCount

Associated context packet count, returned as a 7-bit unsigned integer. This count includes the associated context packets transmitted by a process other than the one that transmits the signal data packet containing the count.

Structure
SignalDataPayloadFormat

Consists of the format of the real or complex signal data (of either 8, 16, or 32 bits) and the data item size, returned as a structure with these fields.

FieldDescription
LinkEfficientPacking

Link-efficient packing indicator, returned as one of these logical values.

  • 1 — Indicates link-efficient packing is used in the paired data packet stream

  • 0 — Indicates processing-efficient packing is used

DataSampleType

Indicates whether the data samples are real or complex Cartesian samples.

DataItemFormat

Five-bit code that indicates the type of data items used in the paired data packet stream. This function supports the decimal values of 0 (signed fixed-point) and 16 (unsigned fixed-point).

RepeatCountIndicator

Repeat count indicator, returned as a logical value of 1 or 0. When returned as 1, it indicates sample component repeating in the paired data packet stream.

EventTagSize

Event tag size field value used in the paired data packet stream, returned as a 3-bit unsigned integer.

ChannelTagSize

Channel tag size field value used in the paired data packet stream, returned as a 4-bit unsigned integer.

DataItemFractionSize

Number of bits in the fraction of a non-normalized number of the format integer.fraction, where the total size of the number is given by the data item size field. The value is returned as a 4-bit unsigned integer.

ItemPackingFieldSize

Item packing field size, returned as a 6-bit unsigned integer. The value is one less than the actual item packing size used in the paired data packet stream.

DataItemSize

Data item size, returned as a 6-bit unsigned integer. This value is one less than the actual data item size used in the paired data packet stream.

RepeatCount

Repeat count, returned as a 16-bit unsigned integer. This value is one less than the actual repeat count used in the paired data packet stream.

VectorSize

Vector size, returned as a 16-bit unsigned integer. This value is one less than the actual vector size used in the paired data packet stream.

Structure

See Also

Functions

Objects

Related Topics