Created
April 6, 2020 17:00
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| extern crate byteorder; | |
| extern crate itertools; | |
| extern crate rustfft; | |
| use byteorder::{LittleEndian, ReadBytesExt}; | |
| use num_complex::Complex; | |
| use rustfft::num_traits::Zero; | |
| use rustfft::FFTplanner; | |
| use std::fs::File; | |
| use std::io::Seek; | |
| use std::io::SeekFrom; | |
| fn main() { | |
| // TODO: read length and start position from capture metadata | |
| // TODO: make a proper function | |
| let path = "/home/mperry/data/rural-sw-testrun-20191219/2019-12-19T16-12-35_318EE00_F2D0791729_Rural-SW/iq_out_RX2_318EE00_0_1576800475.sigmf-data"; | |
| let mut reader = File::open(path).unwrap(); | |
| let start_pos: u64 = 33554432 * 4; // bytes from start of file | |
| // capture["core:sample_start"] * 4 bytes | |
| let len: usize = 4194302 * 2; // number of i16 integers to read (each 2 bytes) | |
| // capture["scan:num_samples"] * 4 bytes / 2 bytes-per-int | |
| // Note that a "sample" is 4 bytes, a pair of i16s | |
| // interpreted as a complex number | |
| assert!(len % 2 == 0); | |
| let mut buffer: Vec<i16> = vec![0i16; len]; | |
| reader.seek(SeekFrom::Start(start_pos)).unwrap(); | |
| reader | |
| .read_i16_into::<LittleEndian>(&mut buffer[..]) | |
| .unwrap(); | |
| // FFT not implemented for i16 yet | |
| // otherwise we could use e.g. https://stackoverflow.com/a/54188098 | |
| // Instead we iterate, cast to complex f32 and build up a new vector | |
| // TODO: apply simple gain offset to get voltage | |
| let mut iq: Vec<Complex<f32>> = Vec::new(); | |
| for chunk in buffer.chunks(2) { | |
| iq.push(Complex::new(chunk[0] as f32, chunk[1] as f32)); | |
| } | |
| let mut output: Vec<Complex<f32>> = vec![Complex::zero(); iq.len()]; | |
| let mut planner = FFTplanner::new(false); | |
| let fft = planner.plan_fft(iq.len()); | |
| fft.process(&mut iq, &mut output); | |
| // println!("{:?}", &output); | |
| } |
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