GnssMeasurement Struct Reference
#include <
gps.h
>
Data Fields |
|
| size_t | size |
| GnssMeasurementFlags | flags |
| int16_t | svid |
| GnssConstellationType | constellation |
| double | time_offset_ns |
| GnssMeasurementState | state |
| int64_t | received_sv_time_in_ns |
| int64_t | received_sv_time_uncertainty_in_ns |
| double | c_n0_dbhz |
| double | pseudorange_rate_mps |
| double | pseudorange_rate_uncertainty_mps |
| GnssAccumulatedDeltaRangeState | accumulated_delta_range_state |
| double | accumulated_delta_range_m |
| double | accumulated_delta_range_uncertainty_m |
| float | carrier_frequency_hz |
| int64_t | carrier_cycles |
| double | carrier_phase |
| double | carrier_phase_uncertainty |
| GnssMultipathIndicator | multipath_indicator |
| double | snr_db |
Detailed Description
Represents a GNSS Measurement, it contains raw and computed information.
Independence - All signal measurement information (e.g. sv_time, pseudorange_rate, multipath_indicator) reported in this struct should be based on GNSS signal measurements only. You may not synthesize measurements by calculating or reporting expected measurements based on known or estimated position, velocity, or time.
Field Documentation
| double accumulated_delta_range_m |
Accumulated delta range since the last channel reset in meters. A positive value indicates that the SV is moving away from the receiver.
The sign of the 'accumulated delta range' and its relation to the sign of 'carrier phase' is given by the equation: accumulated delta range = -k * carrier phase (where k is a constant)
This value must be populated if 'accumulated delta range state' != GPS_ADR_STATE_UNKNOWN. However, it is expected that the data is only accurate when: 'accumulated delta range state' == GPS_ADR_STATE_VALID.
| GnssAccumulatedDeltaRangeState accumulated_delta_range_state |
| double accumulated_delta_range_uncertainty_m |
| double c_n0_dbhz |
| int64_t carrier_cycles |
The number of full carrier cycles between the satellite and the receiver. The reference frequency is given by the field 'carrier_frequency_hz'. Indications of possible cycle slips and resets in the accumulation of this value can be inferred from the accumulated_delta_range_state flags.
If the data is available, 'flags' must contain GNSS_MEASUREMENT_HAS_CARRIER_CYCLES.
| float carrier_frequency_hz |
| double carrier_phase |
The RF phase detected by the receiver, in the range [0.0, 1.0]. This is usually the fractional part of the complete carrier phase measurement.
The reference frequency is given by the field 'carrier_frequency_hz'. The value contains the 'carrier-phase uncertainty' in it.
If the data is available, 'flags' must contain GNSS_MEASUREMENT_HAS_CARRIER_PHASE.
| double carrier_phase_uncertainty |
| GnssConstellationType constellation |
| GnssMeasurementFlags flags |
| GnssMultipathIndicator multipath_indicator |
An enumeration that indicates the 'multipath' state of the event.
The multipath Indicator is intended to report the presence of overlapping signals that manifest as distorted correlation peaks.
- if there is a distorted correlation peak shape, report that multipath is GNSS_MULTIPATH_INDICATOR_PRESENT.
- if there is not a distorted correlation peak shape, report GNSS_MULTIPATH_INDICATOR_NOT_PRESENT
- if signals are too weak to discern this information, report GNSS_MULTIPATH_INDICATOR_UNKNOWN
Example: when doing the standardized overlapping Multipath Performance test (3GPP TS 34.171) the Multipath indicator should report GNSS_MULTIPATH_INDICATOR_PRESENT for those signals that are tracked, and contain multipath, and GNSS_MULTIPATH_INDICATOR_NOT_PRESENT for those signals that are tracked and do not contain multipath.
| double pseudorange_rate_mps |
Pseudorange rate at the timestamp in m/s. The correction of a given Pseudorange Rate value includes corrections for receiver and satellite clock frequency errors. Ensure that this field is independent (see comment at top of GnssMeasurement struct.)
It is mandatory to provide the 'uncorrected' 'pseudorange rate', and provide GpsClock 's 'drift' field as well (When providing the uncorrected pseudorange rate, do not apply the corrections described above.)
The value includes the 'pseudorange rate uncertainty' in it. A positive 'uncorrected' value indicates that the SV is moving away from the receiver.
The sign of the 'uncorrected' 'pseudorange rate' and its relation to the sign of 'doppler shift' is given by the equation: pseudorange rate = -k * doppler shift (where k is a constant)
This should be the most accurate pseudorange rate available, based on fresh signal measurements from this channel.
It is mandatory that this value be provided at typical carrier phase PRR quality (few cm/sec per second of uncertainty, or better) - when signals are sufficiently strong & stable, e.g. signals from a GPS simulator at >= 35 dB-Hz.
| double pseudorange_rate_uncertainty_mps |
| int64_t received_sv_time_in_ns |
The received GNSS Time-of-Week at the measurement time, in nanoseconds. Ensure that this field is independent (see comment at top of GnssMeasurement struct.)
For GPS & QZSS, this is: Received GPS Time-of-Week at the measurement time, in nanoseconds. The value is relative to the beginning of the current GPS week.
Given the highest sync state that can be achieved, per each satellite, valid range for this field can be: Searching : [ 0 ] : GNSS_MEASUREMENT_STATE_UNKNOWN C/A code lock : [ 0 1ms ] : GNSS_MEASUREMENT_STATE_CODE_LOCK is set Bit sync : [ 0 20ms ] : GNSS_MEASUREMENT_STATE_BIT_SYNC is set Subframe sync : [ 0 6s ] : GNSS_MEASUREMENT_STATE_SUBFRAME_SYNC is set TOW decoded : [ 0 1week ] : GNSS_MEASUREMENT_STATE_TOW_DECODED is set
Note well: if there is any ambiguity in integer millisecond, GNSS_MEASUREMENT_STATE_MSEC_AMBIGUOUS should be set accordingly, in the 'state' field.
This value must be populated if 'state' != GNSS_MEASUREMENT_STATE_UNKNOWN.
For Glonass, this is: Received Glonass time of day, at the measurement time in nanoseconds.
Given the highest sync state that can be achieved, per each satellite, valid range for this field can be: Searching : [ 0 ] : GNSS_MEASUREMENT_STATE_UNKNOWN C/A code lock : [ 0 1ms ] : GNSS_MEASUREMENT_STATE_CODE_LOCK is set Symbol sync : [ 0 10ms ] : GNSS_MEASUREMENT_STATE_SYMBOL_SYNC is set Bit sync : [ 0 20ms ] : GNSS_MEASUREMENT_STATE_BIT_SYNC is set String sync : [ 0 2s ] : GNSS_MEASUREMENT_STATE_GLO_STRING_SYNC is set Time of day : [ 0 1day ] : GNSS_MEASUREMENT_STATE_GLO_TOD_DECODED is set
For Beidou, this is: Received Beidou time of week, at the measurement time in nanoseconds.
Given the highest sync state that can be achieved, per each satellite, valid range for this field can be: Searching : [ 0 ] : GNSS_MEASUREMENT_STATE_UNKNOWN C/A code lock: [ 0 1ms ] : GNSS_MEASUREMENT_STATE_CODE_LOCK is set Bit sync (D2): [ 0 2ms ] : GNSS_MEASUREMENT_STATE_BDS_D2_BIT_SYNC is set Bit sync (D1): [ 0 20ms ] : GNSS_MEASUREMENT_STATE_BIT_SYNC is set Subframe (D2): [ 0 0.6s ] : GNSS_MEASUREMENT_STATE_BDS_D2_SUBFRAME_SYNC is set Subframe (D1): [ 0 6s ] : GNSS_MEASUREMENT_STATE_SUBFRAME_SYNC is set Time of week : [ 0 1week ] : GNSS_MEASUREMENT_STATE_TOW_DECODED is set
For Galileo, this is: Received Galileo time of week, at the measurement time in nanoseconds.
E1BC code lock : [ 0 4ms ] : GNSS_MEASUREMENT_STATE_GAL_E1BC_CODE_LOCK is set E1C 2nd code lock: [ 0 100ms ] : GNSS_MEASUREMENT_STATE_GAL_E1C_2ND_CODE_LOCK is set
E1B page : [ 0 2s ] : GNSS_MEASUREMENT_STATE_GAL_E1B_PAGE_SYNC is set Time of week: [ 0 1week ] : GNSS_MEASUREMENT_STATE_TOW_DECODED is set
For SBAS, this is: Received SBAS time, at the measurement time in nanoseconds.
Given the highest sync state that can be achieved, per each satellite, valid range for this field can be: Searching : [ 0 ] : GNSS_MEASUREMENT_STATE_UNKNOWN C/A code lock: [ 0 1ms ] : GNSS_MEASUREMENT_STATE_CODE_LOCK is set Symbol sync : [ 0 2ms ] : GNSS_MEASUREMENT_STATE_SYMBOL_SYNC is set Message : [ 0 1s ] : GNSS_MEASUREMENT_STATE_SBAS_SYNC is set
| int64_t received_sv_time_uncertainty_in_ns |
| double snr_db |
| GnssMeasurementState state |
| int16_t svid |
Satellite vehicle ID number, as defined in GnssSvInfo::svid This is a mandatory value.
| double time_offset_ns |
Time offset at which the measurement was taken in nanoseconds. The reference receiver's time is specified by GpsData::clock::time_ns and should be interpreted in the same way as indicated by GpsClock::type .
The sign of time_offset_ns is given by the following equation: measurement time = GpsClock::time_ns + time_offset_ns
It provides an individual time-stamp for the measurement, and allows sub-nanosecond accuracy. This is a mandatory value.
The documentation for this struct was generated from the following file:
- hardware/libhardware/include/hardware/ gps.h