canisio/Zcu111ResmReceiver
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Organized codegen for fracFdpw. Tested with random input in matlab script. OK

Browse Source
This commit is contained in:
canisio
2026-06-10 09:59:18 -03:00
parent 943b582d66
commit 4f5ac3b5f3
3 changed files with 218 additions and 59 deletions
Download Patch File Download Diff File Expand all files Collapse all files

105
codegen_fracFdpw/fracF_init.m
View File

@@ -1,20 +1,56 @@
function [Achirp,AchirpOut,H,scale] = fracF_init(a)
function [Achirp,H,Cchirp,Aa] = fracF_init(a)
%#codegen
%% fracF_init Precompute FrFT coefficients
%
% fracF_init
% [Achirp,H,Cchirp,Aa] = fracF_init(a)
%
% Precompute FrFT coefficients for DPW processing.
% Generates the constant coefficients required by the code-generation
% implementation of the Fractional Fourier Transform (FrFT).
%
% INPUT:
% a - FrFT order (single)
% The implementation follows the chirp-convolution-chirp formulation:
%
% OUTPUTS:
% Achirp [1024 x 1]
% AchirpOut [512 x 1]
% H [2048 x 1]
% scale scalar
% f(n)
% ↓
% Achirp
% ↓
% FFT
% ↓
% H = FFT(Bchirp)
% ↓
% IFFT
% ↓
% Cchirp
% ↓
% Aa
% ↓
% F_a(n)
%
% These coefficients depend only on the transform order 'a' and can
% therefore be computed once and reused for all frames within a DPW.
%
% INPUT
% a FrFT order (single)
%
% OUTPUTS
% Achirp [1024 x 1] pre-multiplication chirp (A chirp)
% H [2048 x 1] FFT of the convolution chirp (B chirp)
% Cchirp [512 x 1] post-multiplication chirp (C chirp)
% Aa scalar FrFT amplitude factor (A_alpha)
%
% Notes
% - Input length is assumed to be N = 1024 samples.
% - Output length is N/2 = 512 samples.
% - All outputs are returned as complex(single).
% - Intended for use with fracF_dpw().
%
% See also:
% fracF_dpw
N = 1024;
%% Fixed transform dimensions
N = 1024;
%% Transform parameters
pi_s = single(pi);
@@ -27,44 +63,53 @@ cos_phi = cos(phi);
csc_phi = 1/sin_phi;
cot_phi = cos_phi/sin_phi;
twoDelta = 2*sqrt(single(N)/2);
two_delta = 2*sqrt(single(N)/2);
%% Chirp A
%% Pre-multiplication chirp (A chirp)
n = single((-N/2:N/2-1).') / twoDelta;
n = single((-N/2:N/2-1).') / two_delta;
Achirp = exp(-1j*pi_s*(n.^2)*tan_half_phi);
%% Chirp B
%% Convolution chirp (B chirp)
m = single((-N:N-1).') / twoDelta;
m = single((-N:N-1).') / two_delta;
Bchirp = exp(1j*pi_s*csc_phi*(m.^2));
%% FFT of Chirp B
%% Frequency-domain convolution kernel
%
% H corresponds to FFT(Bchirp) and is used in the frequency-domain
% implementation of the chirp convolution.
H = fft(Bchirp);
%% Output chirp
%% Post-multiplication chirp (C chirp)
%
% Since the implementation extracts every other sample from the valid
% convolution region, only the corresponding chirp samples are required.
AchirpOut = Achirp(1:2:end);
Cchirp = Achirp(1:2:end);
%% Scale factor
%% FrFT amplitude factor (A_alpha)
scale = sqrt(1 - 1j*cot_phi) / twoDelta;
Aa = sqrt(1 - 1j*cot_phi) / two_delta;
%% Force single precision complex
%% Force complex(single) outputs
%
% Explicit casting avoids unintended promotion to double precision and
% ensures deterministic code generation.
Achirp = complex(single(real(Achirp)), ...
single(imag(Achirp)));
Achirp = complex(single(real(Achirp)), ...
single(imag(Achirp)));
AchirpOut = complex(single(real(AchirpOut)), ...
single(imag(AchirpOut)));
H = complex(single(real(H)), ...
single(imag(H)));
H = complex(single(real(H)), ...
single(imag(H)));
Cchirp = complex(single(real(Cchirp)), ...
single(imag(Cchirp)));
scale = complex(single(real(scale)), ...
single(imag(scale)));
Aa = complex(single(real(Aa)), ...
single(imag(Aa)));
end