orion-sdr 0.0.20

DSP/SDR block library targeting HF-to-UHF, satellites, and Python bindings. Roadmap inside.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102

// src/modulate/qpsk.rs
use num_complex::Complex32 as C32;
use crate::core::{Block, WorkReport};
use crate::dsp::Rotator;

/// QPSK constellation mapper: two u8 bits (LSBs) → one C32 symbol.
///
/// Gray-coded, normalized to unit energy (1/√2 ≈ 0.7071):
///
///   (b0, b1)  →  constellation point
///   (0, 0)    →  (+1/√2, +1/√2)   Q1
///   (0, 1)    →  (+1/√2, −1/√2)   Q4
///   (1, 0)    →  (−1/√2, +1/√2)   Q2
///   (1, 1)    →  (−1/√2, −1/√2)   Q3
///
/// Input slice is consumed in pairs: input[2k] = b0, input[2k+1] = b1.
/// If the input length is odd the final byte is ignored.
#[derive(Debug, Clone, Copy, Default)]
pub struct QpskMapper;

const FRAC_1_SQRT_2: f32 = std::f32::consts::FRAC_1_SQRT_2;

impl QpskMapper {
    pub fn new() -> Self { Self }
}

#[inline(always)]
fn qpsk_point(b0: u8, b1: u8) -> C32 {
    let re = if (b0 & 1) == 0 {  FRAC_1_SQRT_2 } else { -FRAC_1_SQRT_2 };
    let im = if (b1 & 1) == 0 {  FRAC_1_SQRT_2 } else { -FRAC_1_SQRT_2 };
    C32::new(re, im)
}

impl Block for QpskMapper {
    type In  = u8;
    type Out = C32;

    #[inline(always)]
    fn process(&mut self, input: &[u8], output: &mut [C32]) -> WorkReport {
        let n_syms = (input.len() / 2).min(output.len());
        let mut i = 0;
        let nn = n_syms & !3;
        while i < nn {
            output[i]   = qpsk_point(input[2*i],   input[2*i+1]);
            output[i+1] = qpsk_point(input[2*i+2], input[2*i+3]);
            output[i+2] = qpsk_point(input[2*i+4], input[2*i+5]);
            output[i+3] = qpsk_point(input[2*i+6], input[2*i+7]);
            i += 4;
        }
        while i < n_syms {
            output[i] = qpsk_point(input[2*i], input[2*i+1]);
            i += 1;
        }
        WorkReport { in_read: n_syms * 2, out_written: n_syms }
    }
}

/// QPSK waveform stage: C32 symbols → C32 IQ.
/// rf_hz = 0.0 → baseband passthrough with gain.
/// rf_hz != 0.0 → rotate symbols onto carrier via Rotator.
#[derive(Debug, Clone)]
pub struct QpskMod {
    gain: f32,
    rot:  Rotator,
}

impl QpskMod {
    pub fn new(fs: f32, rf_hz: f32, gain: f32) -> Self {
        Self { gain, rot: Rotator::new(rf_hz, fs) }
    }
    pub fn set_gain(&mut self, g: f32) { self.gain = g; }
}

impl Block for QpskMod {
    type In  = C32;
    type Out = C32;

    #[inline(always)]
    fn process(&mut self, input: &[C32], output: &mut [C32]) -> WorkReport {
        let n = input.len().min(output.len());
        let g = self.gain;
        let mut i = 0;
        let nn = n & !3;
        while i < nn {
            let s0 = input[i];   let r0 = self.rot.next();
            let s1 = input[i+1]; let r1 = self.rot.next();
            let s2 = input[i+2]; let r2 = self.rot.next();
            let s3 = input[i+3]; let r3 = self.rot.next();
            output[i]   = C32::new(g * s0.re.mul_add(r0.re, -s0.im * r0.im), g * s0.im.mul_add(r0.re, s0.re * r0.im));
            output[i+1] = C32::new(g * s1.re.mul_add(r1.re, -s1.im * r1.im), g * s1.im.mul_add(r1.re, s1.re * r1.im));
            output[i+2] = C32::new(g * s2.re.mul_add(r2.re, -s2.im * r2.im), g * s2.im.mul_add(r2.re, s2.re * r2.im));
            output[i+3] = C32::new(g * s3.re.mul_add(r3.re, -s3.im * r3.im), g * s3.im.mul_add(r3.re, s3.re * r3.im));
            i += 4;
        }
        while i < n {
            let s = input[i]; let r = self.rot.next();
            output[i] = C32::new(g * s.re.mul_add(r.re, -s.im * r.im), g * s.im.mul_add(r.re, s.re * r.im));
            i += 1;
        }
        WorkReport { in_read: n, out_written: n }
    }
}