61 lines
1.8 KiB
Rust
61 lines
1.8 KiB
Rust
use super::{iir_int, Complex};
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use serde::{Deserialize, Serialize};
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#[derive(Copy, Clone, Default, Deserialize, Serialize)]
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pub struct Lockin {
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iir: iir_int::IIR,
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iir_state: [iir_int::IIRState; 2],
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}
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impl Lockin {
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/// Create a new Lockin with given IIR coefficients.
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pub fn new(ba: &iir_int::IIRState) -> Self {
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let mut iir = iir_int::IIR::default();
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iir.ba.0.copy_from_slice(&ba.0);
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Lockin {
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iir,
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iir_state: [iir_int::IIRState::default(); 2],
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}
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}
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/// Update the lockin with a sample taken at a given phase.
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pub fn update(&mut self, sample: i32, phase: i32) -> Complex<i32> {
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// Get the LO signal for demodulation.
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let lo = Complex::from_angle(phase);
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// Mix with the LO signal, filter with the IIR lowpass,
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// return IQ (in-phase and quadrature) data.
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// Note: 32x32 -> 64 bit multiplications are pretty much free.
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Complex(
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self.iir.update(
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&mut self.iir_state[0],
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((sample as i64 * lo.0 as i64) >> 32) as _,
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),
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self.iir.update(
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&mut self.iir_state[1],
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((sample as i64 * lo.1 as i64) >> 32) as _,
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),
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)
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}
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/// Feed an iterator into the Lockin and return the latest I/Q data.
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/// Initial stample phase and frequency (phase increment between samples)
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/// are supplied.
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pub fn feed<I: IntoIterator<Item = i32>>(
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&mut self,
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signal: I,
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phase: i32,
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frequency: i32,
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) -> Option<Complex<i32>> {
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let mut phase = phase;
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signal
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.into_iter()
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.map(|sample| {
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phase = phase.wrapping_add(frequency);
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self.update(sample, phase)
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})
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.last()
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}
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}
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