orion-sdr 0.0.10

DSP/SDR block library targeting HF-to-UHF, satellites, and Python bindings. Roadmap inside.
Documentation 
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use num_complex::Complex32 as C32;
use core::f32::consts::TAU;

/// Lightweight NCO used for RF/IF mixing in modulators.
#[derive(Debug, Clone)]
pub struct Nco {
    fs: f32,
    freq_hz: f32,
    phase: f32,
    dphi: f32,
}

impl Nco {
    pub fn new(freq_hz: f32, fs: f32) -> Self {
        let dphi = TAU * freq_hz / fs;
        Self { fs, freq_hz, phase: 0.0, dphi }
    }

    #[inline]
    pub fn set_freq(&mut self, freq_hz: f32) {
        self.freq_hz = freq_hz;
        self.dphi = TAU * freq_hz / self.fs;
    }

    /// Return cos/sin for the current phase and advance by one sample.
    #[inline]
    pub fn next_cs(&mut self) -> (f32, f32) {
        let c = self.phase.cos();
        let s = self.phase.sin();
        self.phase = (self.phase + self.dphi) % TAU;
        (c, s)
    }
}

// Helper to multiply complex sample by e^{jθ} from an NCO
#[inline]
pub fn mix_with_nco(x: C32, nco: &mut Nco) -> C32 {
    let (c, s) = nco.next_cs();
    C32::new(x.re * c - x.im * s, x.re * s + x.im * c)
}