Observation Type Descriptors
R2026bObservation type descriptors is a string comprised of three parts. The first part is the observation type, the second is the frequency band, and the third is the attribute which indicates the tracking mode or channel.
The observation type can be one of five types.
Type
C — Code or pseudorange, is the distance, in meters, between the receiver antenna and the satellite antenna including delays and other biases.
L — Phase is the carrier phase range from the antenna to the satellite, measured in whole cycles.
D — Doppler shift indicating the approach of satellites, where a positive value indicates an approaching satellite.
S — Raw signal strength (carrier to noise ratio) as an integer in the range [1, 9].
X — Receiver channel numbers.
You can identify the frequency band code number given a frequency band and a satellite system.
Frequency Band vs Satellite System
| Frequency Band Code Number | GPS | QZSS | SBAS | BDS | GLO | GAL | NavIC/IRNSS |
|---|---|---|---|---|---|---|---|
| 1 | L1 | L1 | L1 | L1 | G1 | E1 | — |
| 2 | L2 | L2 | — | B1 | G2 | — | — |
| 3 | — | — | — | — | G3 | — | — |
| 4 | — | — | — | — | G1a | — | — |
| 5 | L5 | L5 | L5 | B2a | — | E5a | L5 |
| 6 | — | L6 | — | B3 or B3A | G2a | E6 | — |
| 7 | — | — | — | B2 or B2b | — | E5b | — |
| 8 | — | — | — | B2a and B2b | — | E5a and E5b | — |
| 9 | — | — | — | — | — | — | S |
You can identify the attribute letter given a channel or code and a satellite system.
Attribute vs Satellite System
| Attribute Letter | GPS | QZSS | SBAS | BDS | GLO | GAL | NavIC/IRNSS |
|---|---|---|---|---|---|---|---|
| A | — | — | — | — | A channel | A channel | A channel |
| B | — | — | — | — | A channel | A channel | A channel |
| C | C code-based | C code-based | C code-based | — | C code-based | C channel | C channel |
| D | Semi-codeless | Semi-codeless | — | Data channel | — | — | — |
| E | — | E channel | — | — | — | — | — |
| I | I channel | I channel | — | I channel | — | I channel | — |
| L |
L channel (L2C GPS) P channel |
L channel P channel | — | — | — | — | — |
| M | M-based code | — | — | — | — | — | — |
| N | Codeless | — | — | — | — | — | — |
| P | P code-based | — | — | Pilot channel | P code-based | — | — |
| Q | Q channel | Q channel | — | Q channel | — | Q channel | — |
| S |
D channel M channel (L2C GPS) |
D channel M channel | — | — | — | — | — |
| W | Based on Z-tracking | — | — | — | — | — | — |
| X |
I and Q channels M and L channels D and P channels |
I and Q channels M and L channels D and P channels | — |
I and Q channels D and P channels | — |
B and C channels I and Q channels | B and C channels |
| Y | Y code-based | — | — | — | — | — | — |
| Z | — |
I and Q channels D and E channels | — | D and P channels | — | A, B, and C channels | — |
These are examples of codes:
C1M — L1 pseudorange derived from the M channel for a GPS satellite.
L5X — E5a carrier phase derived from the B and C channels for a Galileo satellite.
S3I — G3 signal strength derived from the I channels for a GLONASS satellite.
References
[1] Romero, Ignacio, ed. RINEX The Receiver Independent Exchange Format Version 3.05. Darmstadt, Germany: IGS/RTCM ESA/ESOC/Navigation Support Office. December, 2020. Accessed on: Dec. 22, 2021. https://files.igs.org/pub/data/format/rinex305.pdf .
