45 lines
1.2 KiB
Rust
45 lines
1.2 KiB
Rust
use super::{
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iir_int::{Vec5, IIR},
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Complex,
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};
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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,
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state: [Vec5; 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: Vec5) -> Self {
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Self {
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iir: IIR {
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ba,
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..Default::default()
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},
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state: [Vec5::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.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.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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}
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