edef1dbed3
Created checkCounterSamples.m to validate sample continuity, counter wraps, and frame index progression. Verified counter bypass, sine bypass, and channelizer modes up to nFrames=1024 across 10 DPWs on ZCU111.
80 lines
1.9 KiB
Matlab
80 lines
1.9 KiB
Matlab
function F = fracF_cg(f, a)
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%#codegen
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%% fracF_cg Fractional Fourier Transform (FrFT) - codegen-ready version
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%
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% Author: Canisio Barth
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%
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% F = fracF_cg(f, a) computes the Fractional Fourier Transform (FrFT)
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% of the input signal 'f' for a single transform order 'a'.
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%
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% This version is adapted for MATLAB Coder and hardware-oriented workflows.
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%
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% Key characteristics:
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% - Fixed input size: [1024 x 1] complex(single)
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% - Output size: [512 x 1] complex(single)
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% - Assumes input 'f' is already interpolated externally
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% - No input validation (assumes valid scalar 'a' in core region)
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% - Deterministic execution (no branching, no dynamic allocation)
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%
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% INPUTS:
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% f - [1024 x 1] complex(single)
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% a - scalar single
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%
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% OUTPUTS:
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% F - [512 x 1] complex(single)
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%
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% Notes:
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% - Internal FFT size = 2048
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% - Designed for code generation and future FPGA mapping
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% Fixed sizes
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N = 1024;
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%N2 = 512;
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Nfft = 2048;
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% Ensure types
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pi_s = single(pi);
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% Transform parameter
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phi = a * (pi_s / 2);
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% Precompute trig terms
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tan_half_phi = tan(phi / 2);
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sin_phi = sin(phi);
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cos_phi = cos(phi);
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csc_phi = 1 / sin_phi;
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cot_phi = cos_phi / sin_phi;
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twoDelta = 2 * sqrt(single(N) / 2);
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%% === Chirp A ===
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n = single((-N/2:N/2-1).') / twoDelta;
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Achirp = exp(-1j * pi_s * (n .* n) * tan_half_phi);
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%% Chirp multiplication #1
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g = Achirp .* f;
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%% === Chirp B ===
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m = single((-N:N-1).') / twoDelta;
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Bchirp = exp(1j * pi_s * csc_phi .* (m .* m));
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%% === Zero-padded buffer ===
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g_pad = complex(zeros(Nfft,1,'single'));
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g_pad(1:N) = g;
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%% === FFT convolution ===
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G = ifft( fft(g_pad) .* fft(Bchirp) );
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%% Extract valid part and decimate
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G_valid = G(N+1:2:end); % [512 x 1]
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%% Complex phase constant
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Aphi = sqrt(1 - 1j * cot_phi);
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%% === Chirp multiplication #2 ===
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F = (Aphi / twoDelta) .* G_valid .* Achirp(1:2:end);
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end |