feat: report nav-message data frequency for a decoder state

Project.toml

@@ -20,7 +20,7 @@ DataStructures = "0.18, 0.19"
 Dictionaries = "0.4"
 DocStringExtensions = "0.6, 0.7, 0.8, 0.9"
 Downloads = "1"
-GNSSSignals = "3.2"
+GNSSSignals = "3.3"
 Random = "1"
 Test = "1"
 Tracking = "2"

docs/src/api.md

@@ -35,6 +35,22 @@ reset_decoder_state
 is_sat_healthy
 ```
 
+## Signal Metadata
+
+`GNSSSignals.get_data_frequency` is extended for [`GNSSDecoderState`](@ref): it
+returns the navigation-message symbol rate of the signal the decoder demodulates
+(e.g. `50 Hz` for GPS L1 C/A, `100 Hz` for GPS L5-I, `50 Hz` for GPS L2C-M). It
+forwards to the corresponding signal's rate in GNSSSignals, so the value stays
+single-sourced. Dispatch is on the constants type, which keeps decoders that
+share a data container distinct — GPS L5-I and L2C-M both decode into
+`GPSCNAVData` but report their own rates.
+
+```julia
+using GNSSDecoder, GNSSSignals
+get_data_frequency(GPSL5IDecoderState(1))   # 100 Hz
+get_data_frequency(GPSL2CMDecoderState(1))  #  50 Hz
+```
+
 ## Shared Utilities
 
 Signal-independent building blocks used across the decoders (CRC-24Q, the

src/galileo/e1b.jl

@@ -575,6 +575,13 @@ function GNSSDecoderState(system::GalileoE1B_BOC11, prn)
     GalileoE1BDecoderState(prn)
 end
 
+# Both the full CBOC E1B and its BOC(1,1) approximation decode into
+# `GalileoE1BConstants` and carry the identical 250 Hz I/NAV symbol stream, so a
+# single method keyed on the constants type serves both. Forwarded from
+# GNSSSignals (see `src/gps/l1ca.jl`).
+GNSSSignals.get_data_frequency(::GNSSDecoderState{<:Any,GalileoE1BConstants}) =
+    get_data_frequency(GalileoE1B)
+
 """
 $(TYPEDSIGNATURES)
 

src/galileo/e5a.jl

@@ -528,6 +528,11 @@ function GNSSDecoderState(system::GalileoE5aI, prn)
     GalileoE5aDecoderState(prn)
 end
 
+# F/NAV symbol rate, forwarded from GNSSSignals (see `src/gps/l1ca.jl`). The
+# decoder runs on the E5a-I data component, so the rate is E5a-I's.
+GNSSSignals.get_data_frequency(::GNSSDecoderState{<:Any,GalileoE5aConstants}) =
+    get_data_frequency(GalileoE5aI)
+
 """
 $(TYPEDSIGNATURES)
 

src/gps/l1c_d.jl

@@ -750,6 +750,10 @@ function GNSSDecoderState(system::GPSL1C_D, prn)
     GPSL1C_DDecoderState(prn)
 end
 
+# Nav-message symbol rate, forwarded from GNSSSignals (see `src/gps/l1ca.jl`).
+GNSSSignals.get_data_frequency(::GNSSDecoderState{<:Any,GPSL1C_DConstants}) =
+    get_data_frequency(GPSL1C_D)
+
 """
 $(TYPEDSIGNATURES)
 

src/gps/l1ca.jl

@@ -529,6 +529,13 @@ function GNSSDecoderState(system::GPSL1CA, prn)
     GPSL1CADecoderState(prn)
 end
 
+# Navigation-message symbol rate of the signal this decoder demodulates,
+# forwarded from GNSSSignals so the rate stays single-sourced. Dispatched on the
+# constants type, which is 1:1 with the signal (and is what tells apart decoders
+# that share a data type — see the GPS CNAV note in `src/gps/l5.jl`).
+GNSSSignals.get_data_frequency(::GNSSDecoderState{<:Any,GPSL1CAConstants}) =
+    get_data_frequency(GPSL1CA)
+
 """
 $(TYPEDSIGNATURES)
 

src/gps/l2c.jl

@@ -92,6 +92,11 @@ function GNSSDecoderState(system::GPSL2CM, prn)
     GPSL2CMDecoderState(prn)
 end
 
+# L2C-M's CNAV symbol rate; keyed on the constants type so it stays distinct from
+# L5-I despite sharing `GPSCNAVData` (see `src/gps/l5.jl`).
+GNSSSignals.get_data_frequency(::GNSSDecoderState{<:Any,GPSL2CMConstants}) =
+    get_data_frequency(GPSL2CM)
+
 """
 $(TYPEDSIGNATURES)
 

src/gps/l5.jl

@@ -72,6 +72,13 @@ function GNSSDecoderState(system::GPSL5I, prn)
     GPSL5IDecoderState(prn)
 end
 
+# GPS CNAV rides on both L5-I (100 sps) and L2C-M (50 sps) but decodes into a
+# single `GPSCNAVData`, so the symbol rate is keyed on the constants type
+# (`GPSL5IConstants` vs `GPSL2CMConstants`) — the only thing that tells the two
+# decoders apart. Forwarded from GNSSSignals (see `src/gps/l1ca.jl`).
+GNSSSignals.get_data_frequency(::GNSSDecoderState{<:Any,GPSL5IConstants}) =
+    get_data_frequency(GPSL5I)
+
 """
 $(TYPEDSIGNATURES)
 

test/data_frequency.jl

@@ -0,0 +1,26 @@
+@testset "Navigation-message data frequency" begin
+    # `get_data_frequency` on a decoder state forwards to the GNSSSignals data
+    # rate of the signal it demodulates, so a decoder state can report its own
+    # nav-message symbol rate without the caller re-deriving which signal it is.
+    signal_of_state = [
+        (GPSL1CADecoderState(1), GPSL1CA),
+        (GPSL1C_DDecoderState(1), GPSL1C_D),
+        (GPSL5IDecoderState(1), GPSL5I),
+        (GPSL2CMDecoderState(1), GPSL2CM),
+        (GalileoE1BDecoderState(1), GalileoE1B),
+        (GalileoE5aDecoderState(1), GalileoE5aI),
+    ]
+    for (state, signal) in signal_of_state
+        @test get_data_frequency(state) == get_data_frequency(signal)
+    end
+
+    # GPS L5-I and L2C-M share `GPSCNAVData` but run at different symbol rates;
+    # dispatch on the constants type must keep them distinct.
+    @test get_data_frequency(GPSL5IDecoderState(1)) !=
+          get_data_frequency(GPSL2CMDecoderState(1))
+
+    # The E1B BOC(1,1) approximation decodes the identical I/NAV stream, so its
+    # decoder reports the same rate as full E1B.
+    @test get_data_frequency(GNSSDecoder.GNSSDecoderState(GalileoE1B_BOC11(), 1)) ==
+          get_data_frequency(GalileoE1B)
+end

test/runtests.jl

@@ -33,6 +33,7 @@ end
     end
 
     include("gnss_supertype.jl")
+    include("data_frequency.jl")
     include("bit_fiddling.jl")
     include("gpsl1.jl")
     include("gps_l1c_d.jl")