Add comments to .proto files

docs/protobuf/gnss_synchro.proto

@@ -2,39 +2,41 @@ syntax = "proto3";
 
 package gnss_sdr;
 
+/* GnssSynchro represents the processing measurements at a given time taken by a given processing channel */
 message GnssSynchro {
-   string system = 1;
-   string signal = 2;
+   string system = 1;  // GNSS constellation: "G" for GPS, "R" for Glonass, "S" for SBAS, "E" for Galileo and "C" for Beidou.
+   string signal = 2;  // GNSS signal: "1C" for GPS L1 C/A, "1B" for Galileo E1b/c, "1G" for Glonass L1 C/A, "2S" for GPS L2 L2C(M), "2G" for Glonass L2 C/A, "L5" for GPS L5 and "5X" for Galileo E5a
 
-   uint32 prn = 3;
-   int32 channel_id = 4;
+   uint32 prn = 3;  // PRN number
+   int32 channel_id = 4;  // Channel number
 
-   double acq_delay_samples = 5;
-   double acq_doppler_hz = 6;
-   uint64 acq_samplestamp_samples = 7;
-   uint32 acq_doppler_step = 8;
-   bool flag_valid_acquisition = 9;
+   double acq_delay_samples = 5;  // Coarse code delay estimation, in samples
+   double acq_doppler_hz = 6;  // Coarse Doppler estimation in each channel, in Hz
+   uint64 acq_samplestamp_samples = 7;  // Number of samples at signal SampleStamp
+   uint32 acq_doppler_step = 8;  // Step of the frequency bin in the search grid, in Hz
+   bool flag_valid_acquisition = 9;  // Acquisition status
 
-   int64 fs = 10;
-   double prompt_i = 11;
-   double prompt_q = 12;
-   double cn0_db_hz = 13;
-   double carrier_doppler_hz = 14;
-   double carrier_phase_rads = 15;
-   double code_phase_samples = 16;
-   uint64 tracking_sample_counter = 17;
-   bool flag_valid_symbol_output = 18;
-   int32 correlation_length_ms = 19;
+   int64 fs = 10;  // Sampling frequency, in samples per second
+   double prompt_i = 11;  // In-phase (real) component of the prompt correlator output
+   double prompt_q = 12;  // Quadrature (imaginary) component of the prompt correlator output
+   double cn0_db_hz = 13;  // Carrier-to-Noise density ratio, in dB-Hz
+   double carrier_doppler_hz = 14;  // Doppler estimation, in [Hz].
+   double carrier_phase_rads = 15;  // Carrier phase estimation, in rad
+   double code_phase_samples = 16;  // Code phase in samples
+   uint64 tracking_sample_counter = 17;  // Sample counter indicating the number of processed samples
+   bool flag_valid_symbol_output = 18;  // Indicates the validity of signal tracking
+   int32 correlation_length_ms = 19;  // Time duration of coherent correlation integration, in ms
 
-   bool flag_valid_word = 20;
-   uint32 tow_at_current_symbol_ms = 21;
+   bool flag_valid_word = 20;  // Indicates the validity of the decoded navigation message word
+   uint32 tow_at_current_symbol_ms = 21;  // Time of week of the current symbol, in ms
 
-   double pseudorange_m = 22;
-   double rx_time = 23;
-   bool flag_valid_pseudorange = 24;
-   double interp_tow_ms = 25;
+   double pseudorange_m = 22;  // Pseudorange computation, in m
+   double rx_time = 23;  // Receiving time after the start of the week, in s
+   bool flag_valid_pseudorange = 24;  // Pseudorange computation status
+   double interp_tow_ms = 25;  // Interpolated time of week, in ms
 }
 
+/* Observables represents a collection of GnssSynchro annotations */
 message Observables {
   repeated GnssSynchro observable = 1;
 }

docs/protobuf/monitor_pvt.proto

@@ -2,39 +2,41 @@ syntax = "proto3";
 
 package gnss_sdr;
 
+/* MonitorPvt represents a search query, with pagination options to
+ * indicate which results to include in the response. */
 message MonitorPvt {
 
-uint32 tow_at_current_symbol_ms = 1;
-uint32 week = 2;
-double rx_time = 3;
-double user_clk_offset = 4;
+uint32 tow_at_current_symbol_ms = 1;  // Time of week of the current symbol, in ms
+uint32 week = 2;  // PVT GPS week
+double rx_time = 3;  // PVT GPS time
+double user_clk_offset = 4;  // User clock offset, in s
 
-double pos_x = 5;
-double pos_y = 6;
-double pos_z = 7;
-double vel_x = 8;
-double vel_y = 9;
-double vel_z = 10;
+double pos_x = 5;  // Position X component in ECEF, expressed in m
+double pos_y = 6;  // Position Y component in ECEF, expressed in m
+double pos_z = 7;  // Position Z component in ECEF, expressed in m
+double vel_x = 8;  // Velocity X component in ECEF, in m/s
+double vel_y = 9;  // Velocity Y component in ECEF, in m/s
+double vel_z = 10;  // Velocity Z component in ECEF, in m/s
 
-double cov_xx = 11;
-double cov_yy = 12;
-double cov_zz = 13;
-double cov_xy = 14;
-double cov_yz = 15;
-double cov_zx = 16;
+double cov_xx = 11;  // Position variance in the Y component, in m2
+double cov_yy = 12;  // Position variance in the Y component, in m2
+double cov_zz = 13;  // Position variance in the Z component, in m2
+double cov_xy = 14;  // Position XY covariance, in m2
+double cov_yz = 15;  // Position YZ covariance, in m2
+double cov_zx = 16;  // Position ZX covariance, in m2
 
-double latitude = 17;
-double longitude = 18;
-double height = 19;
+double latitude = 17;  // Latitude, in deg. Positive: North
+double longitude = 18;  // Longitude, in deg. Positive: East
+double height = 19;  // Height, in m
 
-uint32 valid_sats = 20;
-uint32 solution_status = 21;
-uint32 solution_type = 22;
-float ar_ratio_factor = 23;
-float ar_ratio_threshold = 24;
+uint32 valid_sats = 20;  // Number of valid satellites
+uint32 solution_status = 21;  // RTKLIB solution status
+uint32 solution_type = 22;  // RTKLIB solution type (0: xyz-ecef, 1: enu-baseline)
+float ar_ratio_factor = 23;  // Ambiguity resolution ratio factor for validation
+float ar_ratio_threshold = 24;  // Ambiguity resolution ratio threshold for validation
 
-double gdop = 25;
-double pdop = 26;
-double hdop = 27;
-double vdop = 28;
+double gdop = 25;  // Geometric Dilution of Precision
+double pdop = 26;  // Position (3D) Dilution of Precision
+double hdop = 27;  // Horizontal Dilution of Precision
+double vdop = 28;  // Vertical Dilution of Precision
 }