Adding efficient methods for CFO application

src/Channel/addCFO.jl

@@ -0,0 +1,30 @@
+"""
+Adding Carrier Frequency Offset δ in Hz to the input signal x sampled at frequency samplingRate (In Hz) with initial phase ϕ (default 0)
+This function does not mutate the input signal. See addCFO! for mutating function.
+In case you want to add normalized CFO, set the samplingRate to 1.
+# --- Syntax 
+y = addCFO(x,delta,samplingRate)
+# --- Input parameters 
+- x : Input signal 
+- δ : Carrier frequency offset [Hz]
+- samplingRate : Sampling rate [Hz]
+# --- Output parameters 
+- y : Signal with CFO
+""" 
+function addCFO(x::Union{AbstractVector{Complex{T}},AbstractVector{T}},δ,samplingRate,ϕ=0) where T
+    y = zeros(Complex{T},length(x))
+    addCFO!(y,x,δ,samplingRate,ϕ)
+    return y
+end
+
+function addCFO!(y::AbstractVector{Complex{T}},x::AbstractVector,δ::Number,samplingRate::Number,ϕ=0) where T
+    # --- Basic array check 
+    @assert length(x) == length(y) "Input and output should have same length (here input x is $(length(x)) and pre-allocated output has size $(length(y))"
+    # --- CFO pulsation 
+    ω = δ / samplingRate 
+    # --- Adding CFO 
+    @inbounds @simd for n ∈ eachindex(x)
+        y[n] = x[n] * Complex{T}(exp(2im*π*ω*( (n-1) + ϕ)))
+    end
+end
+

src/DigitalComm.jl

@@ -49,7 +49,9 @@ export initChannel
 export getChannel 
 export getFIRResponse
 export applyChannel 
-
+include("Channel/addCFO.jl")
+export addCFO
+export addCFO!
 
 
 # ---------------------------------------------------- 

test/test_addNoise.jl

@@ -32,10 +32,31 @@ println("Tests for noise addition");
 	addNoise!(mem,qamSeq,snrVise);
 	snr		= -10*log10(mean(abs2.(qamSeq .- mem)));
 	@test abs2(snr - snrVise) < 0.1
-
-
-
-
+end 
+
+@testset "Testing addCFO.jl..." begin 
+    # We check with array of ones, to be sure rotation is Ok
+    x = ones(2048)
+    y = addCFO(x,0,1,0)
+    @test length(x) == length(y)
+    @test all(x .== y)
+    addCFO!(y,x,0,1,0)
+    @test all(x .== y)
+
+    # Check it works with complex input 
+    x = randn(ComplexF64,1024)
+    y = addCFO(x,0,1,0)
+
+    # Check that F32 is not promoted to F64 
+    x2 = randn(ComplexF32,1024)
+    y = addCFO(x2,100,1e3,0)
+    @test y isa Vector{ComplexF32}
+
+
+    # Check that CFO is applied 
+    y = addCFO(x,100,1e3)
+    @test y[1] == x[1]
+    @test y[2] == x[2] * exp(2im*π*100/1e3)
+    @test y[1024] == x[1024] * exp(2im*π*1023*100/1e3)
 end
 
-