feat(galileo_e1b): support the E1B BOC(1,1) signal

README.md

@@ -18,7 +18,7 @@ Currently implemented:
  * GPS L1C-D (CNAV-2)
  * GPS L2C (CNAV)
  * GPS L5I (CNAV)
- * Galileo E1B (I/NAV)
+ * Galileo E1B (I/NAV), including the BOC(1,1) approximation
  * Galileo E5a (F/NAV)
 
 ## Installation

src/galileo/e1b.jl

@@ -586,6 +586,17 @@ function GNSSDecoderState(system::GalileoE1B, prn)
     GalileoE1BDecoderState(prn)
 end
 
+# GalileoE1B_BOC11 is the BOC(1,1) approximation of Galileo E1B — a lower
+# sampling-rate replica many software receivers substitute for the full
+# CBOC(6,1,1/11) spec (see GNSSSignals.jl `GalileoE1B_BOC11`). It carries the
+# *identical* I/NAV navigation message: same 4092-chip primary code, same
+# 250 bps data rate, same page/word structure. The modulation difference is a
+# tracking/acquisition concern only, so decoding reuses the E1B decoder
+# unchanged.
+function GNSSDecoderState(system::GalileoE1B_BOC11, prn)
+    GalileoE1BDecoderState(prn)
+end
+
 """
 $(TYPEDSIGNATURES)
 

test/galileo_e1b.jl

@@ -10,6 +10,15 @@ const GALILEO_E1B_DATA = [
     @test GalileoE1BDecoderState(21) == GNSSDecoderState(galileo_e1b, 21)
 end
 
+@testset "Galileo E1B BOC(1,1) constructor" begin
+    # The BOC(1,1) approximation carries the identical I/NAV message, so it
+    # dispatches to the same decoder state as full-CBOC Galileo E1B.
+    galileo_e1b_boc11 = GalileoE1B_BOC11()
+
+    @test GalileoE1BDecoderState(21) == GNSSDecoderState(galileo_e1b_boc11, 21)
+    @test GNSSDecoderState(GalileoE1B(), 21) == GNSSDecoderState(galileo_e1b_boc11, 21)
+end
+
 @testset "Galileo E1B test data decoding" begin
     decoder = GalileoE1BDecoderState(21)