(Concise Format) Header (17 bytes)

Receive time within the current GPS week (common to code and phase data).

Clock offset value. A value of 0.0 indicates that clock offset is not known.

Number of SV data blocks included in record.

Begin data for first satellite in constellation (block repeated for up to 12 SVs)

Begin Real-Time Survey Data (6 bytes)

Pseudorandom number of satellite (1–32).

Indicates what data is loaded, is valid, etc:

bit 0 set L2 data loaded and phase valid (see also b6)

bit 1 set L1 cycle-slip (since last record 17 write)

bit 2 set L2 cycle-slip (since last record 17 write)

bit 3 L1 phase lock point (redundant, for diagnostics)

bit 4 set L1 phase valid (lock-point valid)

bit 5 set L2 pseudo range valid, reset = squared-L2 phase (for 4000SSE receivers bit 5 = bit 0)

bit 6 set L1 data valid (non-zero but bytes always present) (see also bit 4), reset = only L2 data loaded (see FLAG STATUS field below)

bit 7 set New position computed this receiver cycle

bit 0 ( L1 tracking Mode) 0: C/A Code 1 : P-code

bit 1 ( L2 tracking Mode) 0: C/A Code 1 : P-code

bit 2 (L2 Tracking Encryption Code) 0 : Off 1 : On

bit 3 ( Filtered L1 pseudorange corrections) ) 0 : Off 1 : On

bits 4–7 reserved

Satellite elevation angle (+/-)

Satellite azimuth.

L1 Data: available if bit 6 of Flags 1 set (21 bytes)

Measure of satellite signal strength.

Full L1 C/A code or P-code pseudorange (see bit 0 of FLAGS2).

L1 Continuous Phase. Range-Rate sign convention: When pseudorange is increasing, the phase is decreasing and the Doppler is negative.

L1 Doppler.

L2 Data: Available if bit 0 of FLAGS1 set (13 bytes)

Measure of satellite signal strength

L2 Continuous Phase is in L2 cycles if bit 5 of FLAGS1 = 1

L2 P-Code or L2 Encrypted Code (see bit 1 and bit 2 of FLAGS2) — L1 C/A-Code or P-code (see bit 0 of FLAGS2) pseudorange (valid only if bit 5 of FLAGS1 = 1)

Begin Enhanced Record if bit 1 of the Record Interpretation Flags byte is set to 1 (3 bytes)

Issue of Data Ephemeris

Roll-over counter is incremented for each occurrence of detected cycle-slips on L1 carrier phase

Roll-over counter is incremented for each occurrence of detected cycle-slips on the L2 carrier phase. The counter always increments when L2 changes from C/A code to Encrypted code and vice versa.