# Copyright (C) 2015-2021 Swift Navigation Inc.
# Contact: https://support.swiftnav.com
#
# This source is subject to the license found in the file 'LICENSE' which must
# be distributed together with this source. All other rights reserved.
#
# THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
# EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.

package: swiftnav.sbp.observation
description: Satellite observation messages from the device.
             The SBP sender ID of 0 indicates remote observations
             from a GNSS base station, correction network, or Skylark,
             Swift's cloud GNSS correction product.
stable: True
public: True
include:
  - types.yaml
  - gnss.yaml
definitions:

 - ObservationHeader:
    short_desc: Header for observation message
    desc: Header of a GNSS observation message.
    fields:
        - t:
            type: GPSTime
            desc: GNSS time of this observation
        - n_obs:
            type: u8
            desc: >
              Total number of observations. First nibble is the size
              of the sequence (n), second nibble is the zero-indexed
              counter (ith packet of n)
 - Doppler:
     short_desc: GNSS doppler measurement
     desc: >
       Doppler measurement in Hz represented as a 24-bit
       fixed point number with Q16.8 layout, i.e. 16-bits of whole
       doppler and 8-bits of fractional doppler. This doppler is defined
       as positive for approaching satellites.
     fields:
         - i:
             type: s16
             units: Hz
             desc: Doppler whole Hz
         - f:
             type: u8
             units: Hz / 256
             desc: Doppler fractional part

 - PackedObsContent:
    short_desc: GNSS observations for a particular satellite signal
    desc: >
      Pseudorange and carrier phase observation for a satellite being tracked.
      The observations are interoperable with 3rd party receivers and conform with
      typical RTCM 3.1 message GPS/GLO observations.


      Carrier phase observations are not guaranteed to be aligned to the RINEX 3
      or RTCM 3.3 MSM reference signal and no 1/4 cycle adjustments are currently
      performed.

    fields:
        - P:
            type: u32
            units: 2 cm
            desc: Pseudorange observation
        - L:
            type: CarrierPhase
            units: cycles
            desc: Carrier phase observation with typical sign convention.
        - D:
            type: Doppler
            units: Hz
            desc: Doppler observation with typical sign convention.
        - cn0:
            type: u8
            units: dB Hz / 4
            desc: Carrier-to-Noise density.  Zero implies invalid cn0.
        - lock:
            type: u8
            desc: >
              Lock timer. This value gives an indication of the time
              for which a signal has maintained continuous phase lock.
              Whenever a signal has lost and regained lock, this
              value is reset to zero. It is encoded according to DF402 from
              the RTCM 10403.2 Amendment 2 specification.  Valid values range
              from 0 to 15 and the most significant nibble is reserved for future use.
        - flags:
            type: u8
            desc: >
              Measurement status flags. A bit field of flags providing the
              status of this observation.  If this field is 0 it means only the Cn0
              estimate for the signal is valid.
            fields:
              - 7:
                  desc: RAIM exclusion
                  values:
                      - 0: No exclusion
                      - 1: Measurement was excluded by SPP RAIM, use with care
              - 4-6:
                  desc: Reserved
              - 3:
                  desc: Doppler valid
                  values:
                      - 0: Invalid doppler measurement
                      - 1: Valid doppler measurement
              - 2:
                  desc: Half-cycle ambiguity
                  values:
                      - 0: Half cycle phase ambiguity unresolved
                      - 1: Half cycle phase ambiguity resolved
              - 1:
                  desc: Carrier phase valid
                  values:
                      - 0: Invalid carrier phase measurement
                      - 1: Valid carrier phase measurement
              - 0:
                  desc: Pseudorange valid
                  values:
                      - 0: Invalid pseudorange measurement
                      - 1: Valid pseudorange measurement and coarse TOW decoded
        - sid:
            type: GnssSignal
            desc: GNSS signal identifier (16 bit)