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lockin: cleanup

master
Robert Jördens 2021-01-31 20:32:44 +01:00
parent 1e3e46242d
commit 2d43b8970b
4 changed files with 20 additions and 221 deletions
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99
Cargo.lock generated
View File

@ -348,8 +348,7 @@ dependencies = [
"criterion",
"libm",
"ndarray",
"ndarray-stats",
"rand 0.8.3",
"rand",
"serde",
]
@ -426,17 +425,6 @@ dependencies = [
"version_check",
]
[[package]]
name = "getrandom"
version = "0.1.16"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "8fc3cb4d91f53b50155bdcfd23f6a4c39ae1969c2ae85982b135750cccaf5fce"
dependencies = [
"cfg-if 1.0.0",
"libc",
"wasi 0.9.0+wasi-snapshot-preview1",
]
[[package]]
name = "getrandom"
version = "0.2.2"
@ -445,7 +433,7 @@ checksum = "c9495705279e7140bf035dde1f6e750c162df8b625267cd52cc44e0b156732c8"
dependencies = [
"cfg-if 1.0.0",
"libc",
"wasi 0.10.2+wasi-snapshot-preview1",
"wasi",
]
[[package]]
@ -627,30 +615,6 @@ dependencies = [
"rawpointer",
]
[[package]]
name = "ndarray-stats"
version = "0.4.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "22c95a780960082c5746f6bf0ab22d4a3b8cee72bf580acfe9f1e10bc5ea8152"
dependencies = [
"indexmap",
"itertools 0.9.0",
"ndarray",
"noisy_float",
"num-integer",
"num-traits",
"rand 0.7.3",
]
[[package]]
name = "noisy_float"
version = "0.1.13"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "a14c16cde392a1cd18084ffd8348cb8937525130e62f0478d72dcc683698809d"
dependencies = [
"num-traits",
]
[[package]]
name = "num-complex"
version = "0.3.1"
@ -775,19 +739,6 @@ version = "0.2.2"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "e2a38df5b15c8d5c7e8654189744d8e396bddc18ad48041a500ce52d6948941f"
[[package]]
name = "rand"
version = "0.7.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "6a6b1679d49b24bbfe0c803429aa1874472f50d9b363131f0e89fc356b544d03"
dependencies = [
"getrandom 0.1.16",
"libc",
"rand_chacha 0.2.2",
"rand_core 0.5.1",
"rand_hc 0.2.0",
]
[[package]]
name = "rand"
version = "0.8.3"
@ -795,19 +746,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "0ef9e7e66b4468674bfcb0c81af8b7fa0bb154fa9f28eb840da5c447baeb8d7e"
dependencies = [
"libc",
"rand_chacha 0.3.0",
"rand_core 0.6.1",
"rand_hc 0.3.0",
]
[[package]]
name = "rand_chacha"
version = "0.2.2"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f4c8ed856279c9737206bf725bf36935d8666ead7aa69b52be55af369d193402"
dependencies = [
"ppv-lite86",
"rand_core 0.5.1",
"rand_chacha",
"rand_core",
"rand_hc",
]
[[package]]
@ -817,16 +758,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "e12735cf05c9e10bf21534da50a147b924d555dc7a547c42e6bb2d5b6017ae0d"
dependencies = [
"ppv-lite86",
"rand_core 0.6.1",
]
[[package]]
name = "rand_core"
version = "0.5.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "90bde5296fc891b0cef12a6d03ddccc162ce7b2aff54160af9338f8d40df6d19"
dependencies = [
"getrandom 0.1.16",
"rand_core",
]
[[package]]
@ -835,16 +767,7 @@ version = "0.6.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "c026d7df8b298d90ccbbc5190bd04d85e159eaf5576caeacf8741da93ccbd2e5"
dependencies = [
"getrandom 0.2.2",
]
[[package]]
name = "rand_hc"
version = "0.2.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "ca3129af7b92a17112d59ad498c6f81eaf463253766b90396d39ea7a39d6613c"
dependencies = [
"rand_core 0.5.1",
"getrandom",
]
[[package]]
@ -853,7 +776,7 @@ version = "0.3.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "3190ef7066a446f2e7f42e239d161e905420ccab01eb967c9eb27d21b2322a73"
dependencies = [
"rand_core 0.6.1",
"rand_core",
]
[[package]]
@ -1183,12 +1106,6 @@ dependencies = [
"winapi-util",
]
[[package]]
name = "wasi"
version = "0.9.0+wasi-snapshot-preview1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
[[package]]
name = "wasi"
version = "0.10.2+wasi-snapshot-preview1"

1
dsp/Cargo.toml
View File

@ -12,7 +12,6 @@ serde = { version = "1.0", features = ["derive"], default-features = false }
criterion = "0.3"
rand = "0.8"
ndarray = "0.14"
ndarray-stats = "0.4"
[[bench]]
name = "micro"

138
dsp/src/lockin.rs
View File

@ -8,6 +8,7 @@ pub struct Lockin {
}
impl Lockin {
/// Create a new Lockin with given IIR coefficients.
pub fn new(ba: &iir_int::IIRState) -> Self {
let mut iir = iir_int::IIR::default();
iir.ba.0.copy_from_slice(&ba.0);
@ -17,9 +18,10 @@ impl Lockin {
}
}
pub fn update(&mut self, signal: i32, phase: i32) -> Complex<i32> {
/// Update the lockin with a sample taken at a given phase.
pub fn update(&mut self, sample: i32, phase: i32) -> Complex<i32> {
// Get the LO signal for demodulation.
let m = Complex::from_angle(phase);
let lo = Complex::from_angle(phase);
// Mix with the LO signal, filter with the IIR lowpass,
// return IQ (in-phase and quadrature) data.
@ -27,15 +29,18 @@ impl Lockin {
Complex(
self.iir.update(
&mut self.iir_state[0],
((signal as i64 * m.0 as i64) >> 32) as _,
((sample as i64 * lo.0 as i64) >> 32) as _,
),
self.iir.update(
&mut self.iir_state[1],
((signal as i64 * m.1 as i64) >> 32) as _,
((sample as i64 * lo.1 as i64) >> 32) as _,
),
)
}
/// Feed an iterator into the Lockin and return the latest I/Q data.
/// Initial stample phase and frequency (phase increment between samples)
/// are supplied.
pub fn feed<I: IntoIterator<Item = i32>>(
&mut self,
signal: I,
@ -46,131 +51,10 @@ impl Lockin {
signal
.into_iter()
.map(|s| {
.map(|sample| {
phase = phase.wrapping_add(frequency);
self.update(s, phase)
self.update(sample, phase)
})
.last()
}
}
#[cfg(test)]
mod test {
use crate::{
iir_int::IIRState,
lockin::Lockin,
rpll::RPLL,
testing::{isclose, max_error},
Complex,
};
use std::f64::consts::PI;
use std::vec::Vec;
/// ADC full scale in machine units (16 bit signed).
const ADC_SCALE: f64 = ((1 << 15) - 1) as _;
struct PllLockin {
harmonic: i32,
phase: i32,
lockin: Lockin,
}
impl PllLockin {
pub fn new(harmonic: i32, phase: i32, iir: &IIRState) -> Self {
PllLockin {
harmonic,
phase,
lockin: Lockin::new(iir),
}
}
pub fn update(
&mut self,
input: Vec<i16>,
phase: i32,
frequency: i32,
) -> Complex<i32> {
let sample_frequency = frequency.wrapping_mul(self.harmonic);
let mut sample_phase =
self.phase.wrapping_add(phase.wrapping_mul(self.harmonic));
input
.iter()
.map(|&s| {
let input = (s as i32) << 16;
let signal =
self.lockin.update(input, sample_phase.wrapping_neg());
sample_phase = sample_phase.wrapping_add(sample_frequency);
signal
})
.last()
.unwrap_or(Complex::default())
}
}
/// Single-frequency sinusoid.
#[derive(Copy, Clone)]
struct Tone {
// Frequency (in Hz).
frequency: f64,
// Phase offset (in radians).
phase: f64,
// Amplitude in dBFS (decibels relative to full-scale).
// A 16-bit ADC has a minimum dBFS for each sample of -90.
amplitude_dbfs: f64,
}
/// Convert dBFS to a linear ratio.
fn linear(dbfs: f64) -> f64 {
10f64.powf(dbfs / 20.)
}
impl Tone {
fn eval(&self, time: f64) -> f64 {
linear(self.amplitude_dbfs)
* (self.phase + self.frequency * time).cos()
}
}
/// Generate a full batch of samples with size `sample_buffer_size` starting at `time_offset`.
fn sample_tones(
tones: &Vec<Tone>,
time_offset: f64,
sample_buffer_size: u32,
) -> Vec<i16> {
(0..sample_buffer_size)
.map(|i| {
let time = 2. * PI * (time_offset + i as f64);
let x: f64 = tones.iter().map(|t| t.eval(time)).sum();
assert!(-1. < x && x < 1.);
(x * ADC_SCALE) as i16
})
.collect()
}
/// Total maximum noise amplitude of the input signal after 2nd order lowpass filter.
/// Constructive interference is assumed.
///
/// # Args
/// * `tones` - Noise sources at the ADC input.
/// * `frequency` - Frequency of the signal of interest.
/// * `corner` - Low-pass filter 3dB corner cutoff frequency.
///
/// # Returns
/// Upper bound of the total amplitude of all noise sources in linear units full scale.
fn sampled_noise_amplitude(
tones: &Vec<Tone>,
frequency: f64,
corner: f64,
) -> f64 {
tones
.iter()
.map(|t| {
let df = (t.frequency - frequency) / corner;
// Assuming a 2nd order lowpass filter: 40dB/decade.
linear(t.amplitude_dbfs - 40. * df.abs().max(1.).log10())
})
.sum::<f64>()
.max(1. / ADC_SCALE / 2.) // 1/2 LSB from quantization
}
}

3
dsp/src/rpll.rs
View File

@ -84,7 +84,6 @@ impl RPLL {
mod test {
use super::RPLL;
use ndarray::prelude::*;
use ndarray_stats::QuantileExt;
use rand::{prelude::*, rngs::StdRng};
use std::vec::Vec;
@ -254,7 +253,7 @@ mod test {
h.shift_frequency = 10;
h.shift_phase = 9;
h.measure(1 << 16, [5e-7, 3e-2, 3e-2, 2e-2]);
h.measure(1 << 16, [5e-7, 3e-2, 2e-5, 2e-2]);
}
#[test]