GPGRS

GPS range residuals for each satellite

Platform:

OEM719, OEM729, OEM7500, OEM7600, OEM7700, OEM7720, PwrPak7, CPT7, CPT7700, SMART7, SMART2

Range residuals can be computed in two ways, and this log reports those residuals. Under mode 0, residuals output in this log are used to update the position solution output in the GPGGA message. Under mode 1, the residuals are recomputed after the position solution in the GPGGA message is computed. The receiver computes range residuals in mode 1. An integrity process using GPGRS would also require GPGGA (for position fix data), GPGSA (for DOP figures) and GPGSV (for PRN numbers) for comparative purposes.

The GPGRS log outputs these messages without waiting for a valid almanac. Instead, it uses a UTC time, calculated with default parameters. In this case, the UTC time status (see the TIME log) is set to WARNING since it may not be one hundred percent accurate. When a valid almanac is available, the receiver uses the real parameters. Then the UTC time status is set to VALID.

 

  1. If the range residual exceeds ± 99.9, then the decimal part is dropped. Maximum value for this field is ± 999. The sign of the range residual is determined by the order of parameters used in the calculation as follows:

    range residual = calculated range - measured range

  2. If the NMEATALKER command is set to AUTO, the talker (the first 2 characters after the $ sign in the log header) is set to GP (GPS satellites only), GL (GLONASS satellites only), GA (Galileo satellites only), GB/BD (BDS satellites only), GQ (QZSS satellites only), GI (NavIC satellites only) or GN (combined system satellites).

The position for the GPRMC log is reported in the user selected datum. See the DATUM command for more details.

Message ID: 220

Log Type: Synch

Recommended Input:

log gpgrs ontime 1

Example 1 (NMEATALKER set to GP; GPS only):

$GPGRS,202812.00,1,0.5,0.1,-0.0,-0.0,-0.2,0.8,0.4,-0.3,-0.6,-0.0,,*4A

Example 2 (NMEATALKER set to AUTO; Multi-constellation):

$GNGRS,174837.00,1,-0.1,0.7,-0.2,0.1,0.3,0.5,-0.7,-0.5,-0.3,0.3,,*72

$GNGRS,174837.00,1,2.5,-1.3,-0.4,-0.5,2.8,-2.1,-3.3,,,,,*50

$GNGRS,174837.00,1,-0.3,-0.1,-0.3,-0.5,0.8,-0.3,0.4,0.5,,,,*7D

$GNGRS,174837.00,1,0.2,-0.3,0.1,0.1,-1.3,0.1,0.0,0.3,,,,*5F

See the Note in the GPGGA log that applies to all NMEA logs.

Field

Structure

Description

Symbol

Example

1

$GPGRS

Log header

 

$GPGRS

2

utc

UTC time status of position (hours/minutes/seconds/decimal seconds)

hhmmss.ss

192911.0

3

mode

Mode 0= residuals were used to calculate the position given in the matching GGA line (apriori) (not used by OEM7 receivers)

Mode 1= residuals were recomputed after the GGA position was computed (preferred mode)

x

1

4 - 15

res

Range residuals for satellites used in the navigation solution. Order matches order of PRN numbers in GPGSA

x.x,x.x,.....

-13.8,-1.9,11.4,-33.6,0.9,
6.9,-12.6,0.3,0.6, -22.3

16

system ID

GNSS system ID. See Table: System and Signal IDs. This field is only output if the NMEAVERSION is 4.11 (see the NMEAVERSION command).

h

1

17

signal ID

ID of the ranging signal. See Table: System and Signal IDs

h

1

18

*xx

Check sum

*hh

*65

19

[CR][LF]

Sentence terminator

 

[CR][LF]
System and Signal IDs

GNSS System

System ID

Signal ID

Signal Channel

GPS

1 (GP)

0

All signals

1

L1 C/A

2

L1 P(Y)

3

L1 M

4

L2 P(Y)

5

L2C-M

6

L2C-L

7

L5-I

8

L5-Q

9 - F

Reserved

GLONASS

2 (GL)

0

All signals

1

L1 C/A

2

L1 P

3

L2 C/A

4

L2 P

5 -F

Reserved

Galileo

3 (GA)

0

All signals

1

E5a

2

E5b

3

E5a+b

4

E6-A

5

E6-BC

6

L1-A

7

L1-BC

8 - F

Reserved

BDS (BeiDou System)

4 (GB/BD)

0

All signals

1

B1I

2

B1Q

3

B1C

4

B1A

5

B2-a

6

B2-b

7

B2 a+b

8

B3I

9

B3Q

A

B3A

B

B2I

C

B2Q

D - F

Reserved

QZSS

5 (GQ)

0

All signals

1

L1 C/A

2

L1C (D)

3

L1C (P)

4

LIS

5

L2C-M

6

L2C-L

7

L5-I

8

L5-Q

9

L6D

A

L6E

B - F

Reserved

NavIC

6 (GI)

0

All signals

1

L5-SPS

2

S-SPS

3

L5-RS

4

S-RS

5

L1-SPS

6 - F

Reserved

Reserved

7 - F