NMEA-Sentences

NMEA Sentences Overview

Sentence Construction and Contents

All Iridium PNT NMEA sentences start with the two character GS talker ID. All sentence headers follow the format An NMEA sentence consists of the following components:

1. A start delimiter of '$' 2. A sentence header, or tag 3. A sequence of comma-separated fields 4. The character '*' (ASCII 42) 5. A checksum 6. An end-of-line marker of <CR><LF>

Checksum

Each NEMA message must contain a checksum as the final field. A sentence’s checksum is the 8-bit XOR of the sentence characters, excluding the "$", "I", or "*" characters; but including all "," and "^" characters. It is encoded as two hexadecimal characters (0-9, A-F), the most-significant-nibble being sent first. Sentences are terminated by a <CR><LF>

Some examples: $GSSET,2,101,2,4,1,1*52 $GSGET,2,101,2,6*44

Full List of Iridium PNT Specific NMEA Sentences

Table 1: Supported NMEA Sentences

Sentence Header	Sentence Name	Sentence Description	Sentence Version	Sentence Field Count*	Input/Output	Autonomous Sentence	Priority
GSPPS	PPS Info Sentence	Report Pulse Per Second Timing Information	6	26	Output	X	High
GSPAR	Parameter Report Sentence	Report Rx Parameters	2	Variable	Output		Normal
GSSTA	Statistics Sentence	Report Burst Statistics	3	15	Output	X	Normal
GSSYS	System Status Sentence	Report Rx System Status	3	16	Output	X	Normal
GSRSP	Response Sentence	Report Rx Error Codes	3	6	Output		Normal
GSREQ	Request Sentence	Issue Request To Rx	2	Variable	Input		Normal
GSSET	Set Parameter Sentence	Provide Rx Configuration Parameters	2	Variable	Input		Normal
GSGET	Get Parameter Sentence	Request Rx Configuration Parameter	2	6	Input		Normal
GSLOG	Log/Debug Sentence	Report Log/Debug sentence information	2	Variable	Output	X	Normal
GSPOS	Position Data Sentence	Report Rx Current Position	3	26	Output	X	Normal
GSSSV	Satellites Information Sentence	Report limited satellite location and statistic information	3	Variable	Output	X	Normal
GSSUR	Site Survey Sentence	Site Survey Information	3	16	Output	X	Normal
GSVEL	Velocity Data Sentence	Report Rx Current Velocity Data	2	20	Output	X	Normal
GSSVI	Space Vehicle Information Data Sentence	Report Satellite Ranging & State Data	2	23	Output	X	Normal

*Field count includes the sentence checksum and the sentence header.

NMEA Sentence Frequency / Triggers

All output sentences require a trigger to initiate transmission, some of these are autonomous based on time:

Sentence	Triggering Event(s)
GSPPS	1Hz, (1Hz, or synchronized to PPS Signal)
GSPAR	Upon reception of GSGET
GSRSP	Upon reception of GSREQ, or GSSET
GSSTA	1Hz, (1Hz, or synchronized to PPS Signal)
GSSYS	1Hz, (1Hz, or synchronized to PPS Signal)
GSLOG	Upon request
GSPOS	1Hz, (1Hz, or synchronized to PPS Signal)
GSSSV	0.1 Hz
GSSUR[1]	0.1 Hz, when sentence is enabled
GSVEL	1Hz, (1Hz, or synchronized to PPS Signal)
GSSVI	Updated for each valid burst processed by SDPM

[1] The first GSSUR sentence may take more than 10 seconds after initiating a survey.

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NMEA Sentences Detail

This section contains the field details of the key subset of NMEA sentences provided. If you require detail on sentences not documented here, contact Ground Control.

$GSPPS: PPS Information Sentence

The PPS Information sentence structure is shown in Table 2. The GSPPS sentence contains a TFOM field, defined in Table 3.

Table 2: PPS Information Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Sentence Header	string	$GSPPS
2	Sentence Version	Sentence Version indicator	Int	6
3	GPS Time	Number of whole seconds since GPS Epoch corresponding to the significant (rising) edge of the last PPS output pulse	Int	1362915962
4	UTC GPS Offset	Difference between GPS and UTC Time, in seconds. Empty field indicates invalid data.	Int	18
5	Leap Seconds	An indication of whether a leap second is coming, either positive or negative	Int	0
6	PPS Status	Status of the PPS output signal. Coded: 0 = INIT, 1 = FREERUN, 2 = HOLDOVER, 3 = TRACKING ACTIVE, 4 = TRACKING LOCKABLE	Coded	2
7	PPS Source	Source of the PPS signal. Coded: 0 = NONE, 1 = Iridium PNT, 2 = RESERVED, 3 = RESERVED	Coded	1
8	PPS Accuracy Estimate (ns)	One sigma estimate of PPS accuracy, in ns. _This field dictates the TFOM field value. See Table 3. _	double	133.3
9	TFOM	Time Figure of Merit. See Table 3 for value definitions.	Variable	4
10	Forced Hard Correction Coming	A forced hard correction, or PPS Slew Slam, is about to occur. Asserted 6 seconds prior to the correction.	Int	0
11	Forced Hard Correction Applied	A forced hard correction, or PPS Slew Slam, has just occurred. Remains asserted for 10 seconds after the correction.	Int	0
12	Iridium PNT PPS Status	Status of the Iridium PNT PPS Signal. Coded: 0 = INIT, 1 = ACQUIRING, 2 = LOCKABLE, 3 = ACTIVE	Coded	2
13	Iridium PNT Burst Age	Number of seconds since the previous burst. If no previous burst has been received, value is set to "-1"	double	0.6
14	Iridium PNT PPS Difference (ns)	Difference between PPS out and Iridium PNT PPS. Positive when PPS out is delayed relative to Iridium PNT PPS.	double	0.0
15	Iridium PNT PPS Accuracy Estimate (ns)	Estimation of Iridium PNT PPS accuracy, in ns	double	133.3
16	Reserved	Reserved
17	External PPS Status	Status of the external PPS signal. Coded: 0 = INIT 1 = RESERVED 2 = RESERVED 3 = RESERVED	Coded	0
18	External PPS Difference (ns)	Difference between PPS out and External PPS. Positive when PPS out is delayed relative to External PPS.	double	-44326586.5
19	External PPS Accuracy Estimate (ns)	Estimation of External PPS accuracy, in ns	double
20 to 25	Reserved	Reserved
26	Checksum	N/A	See Sentence Construction and Contents	*43

Table 3: GSPPS TFOM Field Description

TFOM	PPS Accuracy Estimate Range (µs)
1	value ≤ 0.001
2	0.001 < value ≤ 0.01
3	0.01 < value ≤ 0.1
4	0.1 < value ≤ 1
5	1 < value ≤ 10
6	10 < value ≤ 100
7	100 < value ≤ 1,000
8	1,000 < value ≤ 10,000
9	10,000 < value ≤ 100,000
10	100,000 < value ≤ 1,000,000
11	1,000,000 < value ≤ 10,000,000
12	10,000,000 < value ≤ 100,000,000
13	100,000,000 < value ≤ 1,000,000,000
14	1,000,000,000 < value ≤ 10,000,000,000
15	10,000,000,000 < value

Sentence Example

$GSPPS,6,1362915962,18,0,2,1,133.3,4,0,0,2,0.6,0.0,133.3,,0, -44326586.5,,,,,,,*43

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$GSPAR: Parameter Report Sentence

The Parameter Report sentence allows Iridium PNT software to report its configuration. The field count varies with the "Argument Number" field. If Argument Number is greater than 1, the sentence must include additional fields equal to Argument Number minus 1. If Argument Number is 1, no additional fields are required.

Table 4: Parameter Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Sentence Header	string	$GSPAR
2	Sentence Version	Sentence Version indicator	Int	2
3	Parameter ID	Parameter identification number, defined in the Parameter ID Manual [2]	Int
4	Memory Class	Coded indicator of the memory type the argument will modify. 1 = Volatile (Current), 2 = Non-Volatile (Permanent)	Coded
5	Unique Count	Integer counter that increments by one upon reception of a GSGET sentence	Int
6	Argument Number	The number of arguments that describe the parameter, 1 to N	Int
7	Argument 1	Argument 1, from 1 to N, where N = "Argument Number" value	string
...	...	...	...	...
7+N	Argument N	Final argument N, where N = "Argument Number" value	string
8+N	Checksum	N/A	See Sentence Construction and Contents	*xx

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$GSSTA: Statistics Sentence

The statistics sentence reports the prior minute's burst detection, measurement, and processing statistics. It reports key parameters that indicate the RF performance of the receiver.

Table 5: Burst Statistics Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Sentence Header	string	$GSSTA
2	Sentence Version	Sentence Version indicator	Int	3
3 to 6	Reserved	Reserved
7	Processed Burst Count	Number of processed bursts	Int	29133
8	Prior Minute Processed Burst Count	Number of processed bursts within the last 60 seconds	Int	53
9	Prior Minute Average Burst CN0	Average Carrier to Noise Density Ratio of all processed bursts received in the last 60 seconds	double	60.0
10	Prior Minute Maximum Burst CN0	Maximum Carrier to Noise Density Ratio of all processed bursts received in the last 60 seconds	double	70.0
11	Prior Minute Minimum Burst CN0	Minimum Carrier to Noise Density Ratio of all processed bursts received in the last 60 seconds	double	50.0
12 to 14	Reserved	Reserved
15	Checksum	N/A	See Sentence Construction and Contents	*4A

Sentence Example

$GSSTA,3,,,,,29133,53,60.0,70.0,50.0,,,*4A

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$GSSYS: System Status Sentence

The system status sentence reports key parameters and error codes that indicate the general health of the receiver. A bit value of 1 indicates the state is true.

Table 6: System Status Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Sentence Header	string	$GSSYS
2	Sentence Version	Sentence Version indicator	Int	3
3	System Up Time	Number of seconds since system boot	Int	18194
4	Main App Up Time	Number of seconds since the main application started	Int	18169
5	Error†	Error condition detected by the receiver, coded as a bit field. See the list below.	Int	0
6	Subscription Configured†	Bitfield of configured features. See the list below.	Int	0x003
7	Subscription Enabled†	Bitfield of enabled features, when the receiver knows time and can determine a configured feature can be enabled. See the list below.	Int	0x003
8	Subscription Start Date	Start timestamp of subscription, in seconds since the GPS Epoch	Int	1356566417
9	Subscription End Date	End timestamp of subscription, in seconds since the GPS Epoch	Int	1390780817
10	Upgrade Status	Upgrade Status Indicator, _for future use _
11	Extended Status†	Coded bit field of extended status errors and conditions. See Table 7. Error descriptions defined in [3].	Int	0
12	Receiver Application Software Version	Version of the receiver application software	string	1.1
13 to 15	Reserved	Reserved
16	Checksum	N/A	See Sentence Construction and Contents	*6A

Error (Field 5) bit definitions:

• Bit [0]: Missing Serial Number [1]
• Bit [1]: Missing Subscription [2]
• Bit [2]: Missing Model Number (value not set in NVM)
• Bit [3]: Missing Manufacturer (value not set in NVM)
• Bit [4]: Missing Subscription Key (value not set in NVM)
• Bit [5]: Invalid BTFC. Receiver has not yet resolved BTFC.
• Bit [6]: Operational Data Limits Exceeded. Enabled during receiver initialization, and remains enabled until receiver convergence and while the receiver is not in violation of operational limits.

Subscription Configured (Field 6) and Subscription Enabled (Field 7) bit definitions:

• Bit [0]: Location
• Bit [1]: Timing
• Bit [2]: Reserved
• Bit [3]: Reserved
• Bit [4]: Dynamic
• Bit [5]: Raw Measurement

Table 7: Extended Status Bit-field Definition

Bit #	Bit Name	Bit Description
0 to 21	Reserved

Sentence Example

$GSSYS,3,18194,18169,0,0x003,0x003,1356566417,1390780817, ,0,1.1,,,*6A

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$GSRSP: Response Sentence

The response sentence reports the result of the previous GSREQ, GSGET, or GSSET sentence sent to the receiver.

Table 8: Response Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Sentence Header	string	$GSRSP
2	Sentence Version	Sentence Version indicator	Int	3
3	Unique Count	Counter provided in the initial Request, Set, or Get Parameter sentence	Int
4	Result	0 = NACK (Not Acknowledged), 1 = ACK (Acknowledged)	Int
5	Error Code	Error code returned when result is NACK. See Table 9.	Int
6	Checksum	N/A	See Sentence Construction and Contents	*xx

Table 9: Error Code Definition

Error Code	Error Description
1	RESERVED
0	NONE
-1	INVALID_ARG_NB
-2	UNSUPPORTED_PARAM_ID
-3	UNSUPPORTED_MEMORY_CLASS
-4	RESERVED
-5	UNSUPPORTED_REQUEST_ID
-6	PARAMETER_VALUE_TOO_LONG
-7	PARAMETER_IS_UNSET
-8	INVALID_ARG
-9	CANNOT_CHANGE_OTP_PARAMETER
-10	INVALID_OPERATION
-11	UNSUPPORTED_SENTENCE_VERSION

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$GSREQ: Request Sentence

The request sentence provides coded commands to the receiver (e.g. Reset). The field count varies with the "Argument Number" field. If Argument Number is greater than 1, the sentence must include additional fields equal to Argument Number minus 1. If Argument Number is 1, no additional fields are required.

Table 10: Request Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Sentence Header	string	$GSREQ
2	Sentence Version	Sentence Version indicator	Int	2
3	Request ID	Request ID. See Table 11.
4	Unique Count	Counter used to identify the corresponding request when a Response sentence is returned	Int
5	Argument Number	Argument number associated with the command, n out of N	Int
6	Argument 1	The first parameter associated with the command	string
...	...	...	...	...
6+N	Argument N	Final argument N, where N = "Argument Number" value	string
7+N	Checksum	N/A	See Sentence Construction and Contents	*xx

Table 11: Request Command Definitions

Request ID	Command Description	Optional Argument Description
1	Reset	Argument 1: 1 = Reserved, 2 = Reserved, 3 = Reserved, 4 = System reboot
2	RESERVED
3	RESERVED
4	RESERVED
5	Clear a non-volatile parameter	Argument 1: Parameter ID. Defined in the Parameter ID Manual [2].
6	Clear All Non-OTP Non-Volatile Memory Parameters	N/A

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$GSSET: Set Parameter Sentence

The set parameter sentence allows the user to change the receiver configuration. The field count varies with the "Argument Number" field, following the same rules as GSREQ.

Table 12: Set Parameter Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Sentence Header	string	$GSSET
2	Sentence Version	Sentence Version indicator	Int	2
3	Parameter ID	Parameter identification number, defined in the Parameter ID Manual [2]	Int
4	Memory Class	Coded indicator of the memory type the argument will modify. 1 = Volatile (Current), 2 = Non-Volatile (Permanent)	Coded
5	Unique Count	Counter used to identify the corresponding request when a Response sentence is returned	Int
6	Argument Number	Argument number associated with the command, n out of N	Int
7	Argument 1	The first parameter associated with the command	string
...	...	...	...	...
7+N	Argument N	Final argument N, where N = "Argument Number" value	string
8+N	Checksum	N/A	See Sentence Construction and Contents	*xx

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$GSGET: Get Parameter Sentence

The get parameter sentence allows the user to poll the receiver configuration.

Table 13: Get Parameter Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Sentence Header	string	$GSGET
2	Sentence Version	Sentence Version indicator	Int	2
3	Parameter ID	Parameter identification number, defined in the Parameter ID Manual [2]	Int
4	Memory Class	Coded indicator of the memory type. 1 = Volatile (Current), 2 = Non-Volatile (Permanent)	Coded
5	Unique Count	Counter used to identify the corresponding request when a Response sentence is returned	Int
6	Checksum	N/A	See Sentence Construction and Contents	*xx

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$GSLOG: Log/Debug Sentence

The log/debug sentence contains an ASCII character array for logging and debugging. It is a free-form, length-limited string.

Table 14: Log Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Sentence Header	string	$GSLOG
2	Sentence Version	Sentence Version indicator	Int	3
3	Total Number of GSLOG Sentences	Sentences packaged in group	Int	2
4	Sentence Number	Sentence Number within the group	Int	1, 2
5	Sentence	ASCII character array	string	Variable
6	Log Level Identifier**	Coded: 0 = ALWAYS, 1 = FATAL, 2 = ERROR, 3 = WARN, 4 = INFO, 5 = DEBUG, 6 = TRACE	Coded	3
7 to 9	Reserved	Reserved
10	Checksum	N/A	See Sentence Construction and Contents	*xx

** Value must be the same for all sentences within a transmission group. Default setting is 3 (WARN).

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$GSPOS: Position Data Sentence

The GSPOS sentence contains Iridium PNT position data output via the Signal Data Processing Module (SDPM).

‡ Altitude is relative to the WGS84 ellipsoid model. See Operational Limits Data Note for more information.

Table 15: Position Data Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Custom Iridium PNT Header	string	$GSPOS
2	Sentence Version	Sentence Version indicator	Int	3
3	Current Time	Current time, formatted according to the Time Format field	Per Time Format	1324335956.0
4	Time Format	Format of Current Time. Coded: 0 = GPS Time	Coded	0
5	Latitude	Latitude, decimal degree notation	double	40.1516018
6	Longitude	Longitude, decimal degree notation	double	-105.116483
7	Altitude‡	Altitude, in meters	double	1523.37
8	X Position	ECEF X position, in meters	double	-1273340.09
9	Y Position	ECEF Y position, in meters	double	-4714088.78
10	Z Position	ECEF Z position, in meters	double	4091848.56
11	East Position Variance	East position estimate variance, in meters squared	double	132.724
12	North Position Variance	North position estimate variance, in meters squared	double	70.551
13	Up Position Variance	Up position estimate variance, in meters squared	double	686.893
14	East-North Position Covariance	East-North position covariance estimate, in meters squared	double	-31.190
15	East-Up Position Covariance	East-Up position covariance estimate, in meters squared	double	118.094
16	North-Up Position Covariance	North-Up position covariance estimate, in meters squared	double	-31.190
17	Burst Age of Data	Age of position, in seconds, since the previous Iridium PNT burst	double	0
18	Reserved	Reserved
19	Kalman Filter Update Age of Data	Age of position, in seconds, since the previous Kalman Filter update	double	1
20	Reserved	Reserved
21	PFOM	Position Figure of Merit. See Table 16.	Variable
22	Receiver Position Mode	Coded: 0 = Static Known Position**, 1 = Static Unknown Position**, 2 = Reserved, 3 = Dynamic, 4 = Reserved	Coded	0
23 to 25	Reserved	Reserved
26	Checksum	N/A	See Sentence Construction and Contents	*72

** "Static known" mode refers to a surveyed position hold. "Static unknown" mode refers to a guessed position.

Table 16: PFOM Field Definition

PFOM	RMS Estimated Position Error (m)
1	value < 25
2	25 ≤ value < 50
3	50 ≤ value < 75
4	75 ≤ value < 100
5	100 ≤ value < 200
6	200 ≤ value < 500
7	500 ≤ value < 1000
8	1000 ≤ value < 5000
9	5000 ≤ value

Sentence Example

$GSPOS,3,1324335956.0,0,40.1516018,-105.1156483,1523.37,-1273340.09, -4714088.78,4091848.56,132.724,70.551,686.893,-31.190,118.094,-31.190,0,,1,,,0,,,*72

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$GSSSV: Satellites Information Sentence

The GSSSV sentence contains satellite information output via the Signal Data Processing Module (SDPM). Sentences are typically packaged in a group of 2 or 3. The "Total Number of Sentences to be Transmitted" and "Total Number of Satellites" fields dictate the size of the package. If the sentence count is greater than 1, the "Total Number of Sentences", "Sentence Number", and "Total Number of Satellites" fields repeat at the start of each sentence. The Satellite ID, Elevation, Azimuth, and CN0 fields are output only once per satellite within the package.

See Operational Limits Data Note for more information.

Table 17: Satellite Information Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	ASCII (Delimiter + Talker ID + Type Code)	string	$GSSSV
2	Sentence Version	Sentence Version indicator	Int	3
3	Total Number of GSSSV Sentences	Sentences packaged in group	Int	4
4	Sentence Number	Sentence Number within the current group	Int	1 to 4
5	Total Number of Satellites	Number of satellites within field of view, with leading zeros	Int	4
6	Satellite ID	Satellite Identification Number	Int	Multiple values
7	Elevation	Elevation angle in degrees	Int [0, 90]	30
8	Azimuth	Azimuth angle in degrees	Int [0, 359]	278
9	Minimum CN0	Minimum Carrier to Noise Density Ratio, in dB-Hz	double	40.0
10	Maximum CN0	Maximum Carrier to Noise Density Ratio, in dB-Hz	double	76.7
11 to 13	Reserved	Reserved
14	Checksum	N/A	See Sentence Construction and Contents	*7B

Sentence Examples

$GSSSV,3,4,1,4,30,16,278,40.0,76.7,,,*7B
$GSSSV,3,4,2,4,40,10,27,37.8,77.8,,,*47
$GSSSV,3,4,3,4,29,,,39.9,70.9,,,*44
$GSSSV,3,4,4,4,41,9,148,40.8,73.8,,,*44

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$GSSUR: Site Survey Sentence

The GSSUR sentence content is reserved for future use.

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$GSVEL: Velocity Data Sentence

The GSVEL sentence contains Iridium PNT velocity data output via the Signal Data Processing Module (SDPM).

◊ See GPS Timestamp Format for more information. See Operational Limits Data Note for more information.

Table 18: Velocity Data Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Custom Sentence Header	ASCII	$GSVEL
2	Sentence Version	Sentence Version indicator	Int	2
3	GPS Time◊	Timestamp of message containing whole and fractional seconds since GPS Epoch	double	83560.10000000
4	East Velocity	Velocity EE, in meters per second	double	0.1
5	North Velocity	Velocity NN, in meters per second	double	0.2
6	Up Velocity	Velocity UU, in meters per second	double	0.3
7	East Velocity Variance	East velocity estimate variance, in m²/s²	double	0.0
8	North Velocity Variance	North velocity estimate variance, in m²/s²	double	0.0
9	Up Velocity Variance	Up velocity estimate variance, in m²/s²	double	0.0
10	East North Velocity Covariance	East-North velocity estimate covariance, in m²/s²	double	0.0
11	East Up Velocity Covariance	East-Up velocity estimate covariance, in m²/s²	double	0.0
12	North Up Velocity Covariance	North-Up velocity estimate covariance, in m²/s²	double	0.0
13	Burst Update Age of Data	Age of data, in seconds, since the previous Iridium burst	double	0
14	Sensor Measurement Update Age of	Age of data, in seconds, since the previous sensor update	double	0
15	Kalman Filter Update Age of Data	Age of data, in seconds, since the previous Kalman Filter update	double	1
16	PVT Validation State	Validation state of the Kalman Filter. Coded: 0 = Not Available, 1 = Initializing, 2 = Pending, 3 = Usable, 4 = Reserved, 5 = Reserved	Coded	3
17 to 19	Reserved	Reserved
20	Checksum	N/A	See Sentence Construction and Contents	*46

Sentence Example

$GSVEL,2,83560.10000000,0.1,0.2,0.3,0.0,0.0,0.0,0.0,0.0,0.0,0,0,1, ,,,*46

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$GSSVI: Space Vehicle Information Data Sentence

The GSSVI sentence contains satellite vehicle information output via the Signal Data Processing Module (SDPM).

◊ See GPS Timestamp Format for more information. See Operational Limits Data Note for more information.

Table 19: Space Vehicle Information Sentence Definition

Field Number	Sentence Field Name	Field Description	Field Format	Example
1	Sentence Header	Custom Sentence Header	ASCII	$GSSVI
2	Sentence Version	Sentence Version indicator	Int	1
3	SV ID	Space Vehicle ID. Any value NOT inclusively between 1 and 66 indicates the ASIC firmware could not confidently detect the SVID. Negative SV IDs are provided for logging and visibility only and are not used to generate a Navigation Solution.	Int	1
4	Time Of Validity◊	Timestamp of message containing whole and fractional seconds since GPS Epoch	double	1324771537.08116000
5	Time Of Arrival◊	Timestamp of the underlying burst in receiver time (time since receiver initialization). Formatted according to GPS Timestamp Format.	double	1830.96981100
6	Burst Counter	A monotonically increasing counter used to uniquely identify received bursts	int	10
7	Pseudorange	Pseudorange estimate from the satellite to the receiver, in meters	double
8	Pseudorange Rate	Pseudorange rate estimate from the satellite to the receiver, in meters per second	double
9	CN0	Carrier to Noise Density Ratio, in dB-Hz	double	58.2
10	Doppler	Doppler, in Hz	double	2611.354248
11	SV X Position	X coordinate ECEF position, in meters	double	-1766791.0
12	SV Y Position	Y coordinate ECEF position, in meters	double	-5132087.0
13	SV Z Position	Z coordinate ECEF position, in meters	double	4656373.6
14	SV X Velocity	X coordinate ECEF velocity, in meters per second	double	1790.4
15	SV Y Velocity	Y coordinate ECEF velocity, in meters per second	double	4516.3
16	SV Z Velocity	Z coordinate ECEF velocity, in meters per second	double	5641.2
17	SV Validation Status	Space Vehicle Validation State. Coded: 0 = Not Available, 1 = Initializing, 2 = Pending, 3 = Usable, 4 = Reserved, 5 = Reserved	Coded	3
18 to 20	Reserved	Reserved
21	Checksum	N/A	See Sentence Construction and Contents	*45

Sentence Example

$GSSVI,1,1,1324771537.08116000,1830.96981100,10,,,58.2,2611.354248,-1766791.0,-5132087.0,4656373.6,1790.4,4516.3,5641.2, ,,,*45