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Merge pull request #243 from quartiq/rpll2 

Rpll2
This commit is contained in:
Robert Jördens 2021-01-31 18:31:03 +01:00 committed by GitHub
parent 0d6b5e894c 43342cef91
commit 12563ff9ab
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6 changed files with 498 additions and 53 deletions
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195
Cargo.lock generated
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@ -347,6 +347,9 @@ version = "0.1.0"
dependencies = [ dependencies = [
"criterion", "criterion",
"libm", "libm",
"ndarray",
"ndarray-stats",
"rand 0.8.3",
"serde", "serde",
] ]
@ -423,6 +426,28 @@ dependencies = [
"version_check", "version_check",
] ]
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]
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@ -533,6 +558,15 @@ version = "0.7.2"
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dependencies = [
"rawpointer",
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@ -571,6 +605,62 @@ version = "1.0.0"
source = "registry+https://github.com/rust-lang/crates.io-index" source = "registry+https://github.com/rust-lang/crates.io-index"
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dependencies = [
"matrixmultiply",
"num-complex",
"num-integer",
"num-traits",
"rawpointer",
]
[[package]]
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"indexmap",
"itertools",
"ndarray",
"noisy_float",
"num-integer",
"num-traits",
"rand 0.7.3",
]
[[package]]
name = "noisy_float"
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dependencies = [
"num-traits",
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[[package]]
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version = "0.3.1"
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dependencies = [
"autocfg",
"num-traits",
]
[[package]] [[package]]
name = "num-traits" name = "num-traits"
version = "0.2.14" version = "0.2.14"
@ -630,6 +720,12 @@ dependencies = [
"web-sys", "web-sys",
] ]
[[package]]
name = "ppv-lite86"
version = "0.2.10"
source = "registry+https://github.com/rust-lang/crates.io-index"
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[[package]] [[package]]
name = "proc-macro2" name = "proc-macro2"
version = "1.0.24" version = "1.0.24"
@ -654,6 +750,93 @@ version = "0.2.2"
source = "registry+https://github.com/rust-lang/crates.io-index" source = "registry+https://github.com/rust-lang/crates.io-index"
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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"
source = "registry+https://github.com/rust-lang/crates.io-index"
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dependencies = [
"libc",
"rand_chacha 0.3.0",
"rand_core 0.6.1",
"rand_hc 0.3.0",
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dependencies = [
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name = "rand_core"
version = "0.6.1"
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checksum = "c026d7df8b298d90ccbbc5190bd04d85e159eaf5576caeacf8741da93ccbd2e5"
dependencies = [
"getrandom 0.2.2",
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[[package]]
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version = "0.2.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
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dependencies = [
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]
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dependencies = [
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]
[[package]]
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version = "0.2.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "60a357793950651c4ed0f3f52338f53b2f809f32d83a07f72909fa13e4c6c1e3"
[[package]] [[package]]
name = "rayon" name = "rayon"
version = "1.5.0" version = "1.5.0"
@ -975,6 +1158,18 @@ dependencies = [
"winapi-util", "winapi-util",
] ]
[[package]]
name = "wasi"
version = "0.9.0+wasi-snapshot-preview1"
source = "registry+https://github.com/rust-lang/crates.io-index"
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[[package]]
name = "wasi"
version = "0.10.2+wasi-snapshot-preview1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
[[package]] [[package]]
name = "wasm-bindgen" name = "wasm-bindgen"
version = "0.2.69" version = "0.2.69"

3
dsp/Cargo.toml
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@ -10,6 +10,9 @@ serde = { version = "1.0", features = ["derive"], default-features = false }
[dev-dependencies] [dev-dependencies]
criterion = "0.3" criterion = "0.3"
rand = "0.8"
ndarray = "0.14"
ndarray-stats = "0.4"
[[bench]] [[bench]]
name = "trig" name = "trig"

55
dsp/src/complex.rs
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@ -1,17 +1,58 @@
use super::atan2; use super::{atan2, cossin};
use serde::{Deserialize, Serialize}; use serde::{Deserialize, Serialize};
#[derive(Copy, Clone, Default, Deserialize, Serialize)] #[derive(Copy, Clone, Default, PartialEq, Debug, Deserialize, Serialize)]
pub struct Complex<T>(pub T, pub T); pub struct Complex<T>(pub T, pub T);
impl Complex<i32> { impl Complex<i32> {
pub fn power(&self) -> i32 { /// Return a Complex on the unit circle given an angle.
(((self.0 as i64) * (self.0 as i64) ///
+ (self.1 as i64) * (self.1 as i64)) /// Example:
>> 32) as i32 ///
/// ```
/// use dsp::Complex;
/// Complex::<i32>::from_angle(0);
/// Complex::<i32>::from_angle(1 << 30); // pi/2
/// Complex::<i32>::from_angle(-1 << 30); // -pi/2
/// ```
#[inline(always)]
pub fn from_angle(angle: i32) -> Complex<i32> {
cossin(angle)
} }
pub fn phase(&self) -> i32 { /// Return the absolute square (the squared magnitude).
///
/// Note: Normalization is `1 << 31`, i.e. Q0.31.
///
/// Example:
///
/// ```
/// use dsp::Complex;
/// assert_eq!(Complex(i32::MAX, 0).abs_sqr(), i32::MAX - 1);
/// assert_eq!(Complex(i32::MIN + 1, 0).abs_sqr(), i32::MAX - 1);
/// ```
pub fn abs_sqr(&self) -> i32 {
(((self.0 as i64) * (self.0 as i64)
+ (self.1 as i64) * (self.1 as i64))
>> 31) as i32
}
/// Return the angle.
///
/// Note: Normalization is `1 << 31 == pi`.
///
/// Example:
///
/// ```
/// use dsp::Complex;
/// assert_eq!(Complex(i32::MAX, 0).arg(), 0);
/// assert_eq!(Complex(-i32::MAX, 1).arg(), i32::MAX);
/// assert_eq!(Complex(-i32::MAX, -1).arg(), -i32::MAX);
/// assert_eq!(Complex(0, -i32::MAX).arg(), -i32::MAX >> 1);
/// assert_eq!(Complex(0, i32::MAX).arg(), (i32::MAX >> 1) + 1);
/// assert_eq!(Complex(i32::MAX, i32::MAX).arg(), (i32::MAX >> 2) + 1);
/// ```
pub fn arg(&self) -> i32 {
atan2(self.1, self.0) atan2(self.1, self.0)
} }
} }

22
dsp/src/lockin.rs
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@ -1,4 +1,4 @@
use super::{cossin, iir_int, Complex}; use super::{iir_int, Complex};
use serde::{Deserialize, Serialize}; use serde::{Deserialize, Serialize};
#[derive(Copy, Clone, Default, Deserialize, Serialize)] #[derive(Copy, Clone, Default, Deserialize, Serialize)]
@ -19,7 +19,7 @@ impl Lockin {
pub fn update(&mut self, signal: i32, phase: i32) -> Complex<i32> { pub fn update(&mut self, signal: i32, phase: i32) -> Complex<i32> {
// Get the LO signal for demodulation. // Get the LO signal for demodulation.
let m = cossin(phase); let m = Complex::from_angle(phase);
// Mix with the LO signal, filter with the IIR lowpass, // Mix with the LO signal, filter with the IIR lowpass,
// return IQ (in-phase and quadrature) data. // return IQ (in-phase and quadrature) data.
@ -35,12 +35,28 @@ impl Lockin {
), ),
) )
} }
pub fn feed<I: IntoIterator<Item = i32>>(
&mut self,
signal: I,
phase: i32,
frequency: i32,
) -> Option<Complex<i32>> {
let mut phase = phase;
signal
.into_iter()
.map(|s| {
phase = phase.wrapping_add(frequency);
self.update(s, phase)
})
.last()
}
} }
#[cfg(test)] #[cfg(test)]
mod test { mod test {
use crate::{ use crate::{
atan2,
iir_int::IIRState, iir_int::IIRState,
lockin::Lockin, lockin::Lockin,
rpll::RPLL, rpll::RPLL,

232
dsp/src/rpll.rs
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@ -3,13 +3,14 @@
/// Consumes noisy, quantized timestamps of a reference signal and reconstructs /// Consumes noisy, quantized timestamps of a reference signal and reconstructs
/// the phase and frequency of the update() invocations with respect to (and in units of /// the phase and frequency of the update() invocations with respect to (and in units of
/// 1 << 32 of) that reference. /// 1 << 32 of) that reference.
/// In other words, `update()` rate ralative to reference frequency,
/// `u32::MAX` corresponding to both being equal.
#[derive(Copy, Clone, Default)] #[derive(Copy, Clone, Default)]
pub struct RPLL { pub struct RPLL {
dt2: u8, // 1 << dt2 is the counter rate to update() rate ratio dt2: u8, // 1 << dt2 is the counter rate to update() rate ratio
t: i32, // current counter time
x: i32, // previous timestamp x: i32, // previous timestamp
ff: i32, // current frequency estimate from frequency loop ff: u32, // current frequency estimate from frequency loop
f: i32, // current frequency estimate from both frequency and phase loop f: u32, // current frequency estimate from both frequency and phase loop
y: i32, // current phase estimate y: i32, // current phase estimate
} }
@ -18,14 +19,12 @@ impl RPLL {
/// ///
/// Args: /// Args:
/// * dt2: inverse update() rate. 1 << dt2 is the counter rate to update() rate ratio. /// * dt2: inverse update() rate. 1 << dt2 is the counter rate to update() rate ratio.
/// * t: Counter time. Counter value at the first update() call. Typically 0.
/// ///
/// Returns: /// Returns:
/// Initialized RPLL instance. /// Initialized RPLL instance.
pub fn new(dt2: u8, t: i32) -> RPLL { pub fn new(dt2: u8) -> RPLL {
RPLL { RPLL {
dt2, dt2,
t,
..Default::default() ..Default::default()
} }
} }
@ -43,42 +42,231 @@ impl RPLL {
/// ///
/// Returns: /// Returns:
/// A tuple containing the current phase (wrapping at the i32 boundary, pi) and /// A tuple containing the current phase (wrapping at the i32 boundary, pi) and
/// frequency (wrapping at the i32 boundary, Nyquist) estimate. /// frequency.
pub fn update( pub fn update(
&mut self, &mut self,
input: Option<i32>, input: Option<i32>,
shift_frequency: u8, shift_frequency: u8,
shift_phase: u8, shift_phase: u8,
) -> (i32, i32) { ) -> (i32, u32) {
debug_assert!(shift_frequency > self.dt2); debug_assert!(shift_frequency > self.dt2);
debug_assert!(shift_phase > self.dt2); debug_assert!(shift_phase >= self.dt2);
// Advance phase // Advance phase
self.y = self.y.wrapping_add(self.f); self.y = self.y.wrapping_add(self.f as i32);
if let Some(x) = input { if let Some(x) = input {
// Reference period in counter cycles // Reference period in counter cycles
let dx = x.wrapping_sub(self.x); let dx = x.wrapping_sub(self.x);
// Store timestamp for next time. // Store timestamp for next time.
self.x = x; self.x = x;
// Phase using the current frequency estimate // Phase using the current frequency estimate
let p_sig_long = (self.ff as i64).wrapping_mul(dx as i64); let p_sig_64 = self.ff as u64 * dx as u64;
// Add half-up rounding bias and apply gain/attenuation // Add half-up rounding bias and apply gain/attenuation
let p_sig = (p_sig_long.wrapping_add(1i64 << (shift_frequency - 1)) let p_sig = ((p_sig_64 + (1u32 << (shift_frequency - 1)) as u64)
>> shift_frequency) as i32; >> shift_frequency) as u32;
// Reference phase (1 << dt2 full turns) with gain/attenuation applied // Reference phase (1 << dt2 full turns) with gain/attenuation applied
let p_ref = 1i32 << (32 + self.dt2 - shift_frequency); let p_ref = 1u32 << (32 + self.dt2 - shift_frequency);
// Update frequency lock // Update frequency lock
self.ff = self.ff.wrapping_add(p_ref.wrapping_sub(p_sig)); self.ff = self.ff.wrapping_add(p_ref.wrapping_sub(p_sig) as u32);
// Time in counter cycles between timestamp and "now" // Time in counter cycles between timestamp and "now"
let dt = self.t.wrapping_sub(x); let dt = (x.wrapping_neg() & ((1 << self.dt2) - 1)) as u32;
// Reference phase estimate "now" // Reference phase estimate "now"
let y_ref = (self.f >> self.dt2).wrapping_mul(dt); let y_ref = (self.f >> self.dt2).wrapping_mul(dt) as i32;
// Phase error // Phase error with gain
let dy = y_ref.wrapping_sub(self.y); let dy = y_ref.wrapping_sub(self.y) >> (shift_phase - self.dt2);
// Current frequency estimate from frequency lock and phase error // Current frequency estimate from frequency lock and phase error
self.f = self.ff.wrapping_add(dy >> (shift_phase - self.dt2)); self.f = self.ff.wrapping_add(dy as u32);
} }
// Advance time
self.t = self.t.wrapping_add(1 << self.dt2);
(self.y, self.f) (self.y, self.f)
} }
} }
#[cfg(test)]
mod test {
use super::RPLL;
use ndarray::prelude::*;
use ndarray_stats::QuantileExt;
use rand::{prelude::*, rngs::StdRng};
use std::vec::Vec;
#[test]
fn make() {
let _ = RPLL::new(8);
}
struct Harness {
rpll: RPLL,
dt2: u8,
shift_frequency: u8,
shift_phase: u8,
noise: i32,
period: i32,
next: i32,
next_noisy: i32,
time: i32,
rng: StdRng,
}
impl Harness {
fn default() -> Self {
Harness {
rpll: RPLL::new(8),
dt2: 8,
shift_frequency: 9,
shift_phase: 8,
noise: 0,
period: 333,
next: 111,
next_noisy: 111,
time: 0,
rng: StdRng::seed_from_u64(42),
}
}
fn run(&mut self, n: usize) -> (Vec<f32>, Vec<f32>) {
let mut y = Vec::<f32>::new();
let mut f = Vec::<f32>::new();
for _ in 0..n {
let timestamp = if self.time - self.next_noisy >= 0 {
assert!(self.time - self.next_noisy < 1 << self.dt2);
self.next = self.next.wrapping_add(self.period);
let timestamp = self.next_noisy;
let p_noise = self.rng.gen_range(-self.noise..=self.noise);
self.next_noisy = self.next.wrapping_add(p_noise);
Some(timestamp)
} else {
None
};
let (yi, fi) = self.rpll.update(
timestamp,
self.shift_frequency,
self.shift_phase,
);
let y_ref = (self.time.wrapping_sub(self.next) as i64
* (1i64 << 32)
/ self.period as i64) as i32;
// phase error
y.push(yi.wrapping_sub(y_ref) as f32 / 2f32.powi(32));
let p_ref = 1 << 32 + self.dt2;
let p_sig = fi as u64 * self.period as u64;
// relative frequency error
f.push(
p_sig.wrapping_sub(p_ref) as i64 as f32
/ 2f32.powi(32 + self.dt2 as i32),
);
// advance time
self.time = self.time.wrapping_add(1 << self.dt2);
}
(y, f)
}
fn measure(&mut self, n: usize, limits: [f32; 4]) {
assert!(self.period >= 1 << self.dt2);
assert!(self.dt2 <= self.shift_frequency);
assert!(self.period < 1 << self.shift_frequency);
assert!(self.period < 1 << self.shift_frequency + 1);
let t_settle = (1 << self.shift_frequency - self.dt2 + 4)
+ (1 << self.shift_phase - self.dt2 + 4);
self.run(t_settle);
let (y, f) = self.run(n);
let y = Array::from(y);
let f = Array::from(f);
// println!("{:?} {:?}", f, y);
let fm = f.mean().unwrap();
let fs = f.std_axis(Axis(0), 0.).into_scalar();
let ym = y.mean().unwrap();
let ys = y.std_axis(Axis(0), 0.).into_scalar();
println!("f: {:.2e}±{:.2e}; y: {:.2e}±{:.2e}", fm, fs, ym, ys);
let m = [fm, fs, ym, ys];
print!("relative: ");
for i in 0..m.len() {
let rel = m[i].abs() / limits[i].abs();
print!("{:.2e} ", rel);
assert!(
rel <= 1.,
"idx {}, have |{}| > want {}",
i,
m[i],
limits[i]
);
}
println!();
}
}
#[test]
fn default() {
let mut h = Harness::default();
h.measure(1 << 16, [1e-11, 4e-8, 2e-8, 2e-8]);
}
#[test]
fn noisy() {
let mut h = Harness::default();
h.noise = 10;
h.shift_frequency = 23;
h.shift_phase = 22;
h.measure(1 << 16, [3e-9, 3e-6, 4e-4, 2e-4]);
}
#[test]
fn narrow_fast() {
let mut h = Harness::default();
h.period = 990;
h.next = 351;
h.next_noisy = h.next;
h.noise = 5;
h.shift_frequency = 23;
h.shift_phase = 22;
h.measure(1 << 16, [2e-9, 2e-6, 1e-3, 1e-4]);
}
#[test]
fn narrow_slow() {
let mut h = Harness::default();
h.period = 1818181;
h.next = 35281;
h.next_noisy = h.next;
h.noise = 1000;
h.shift_frequency = 23;
h.shift_phase = 22;
h.measure(1 << 16, [2e-5, 6e-4, 2e-4, 2e-4]);
}
#[test]
fn wide_fast() {
let mut h = Harness::default();
h.period = 990;
h.next = 351;
h.next_noisy = h.next;
h.noise = 5;
h.shift_frequency = 10;
h.shift_phase = 9;
h.measure(1 << 16, [5e-7, 3e-2, 3e-2, 2e-2]);
}
#[test]
fn wide_slow() {
let mut h = Harness::default();
h.period = 1818181;
h.next = 35281;
h.next_noisy = h.next;
h.noise = 1000;
h.shift_frequency = 21;
h.shift_phase = 20;
h.measure(1 << 16, [2e-4, 6e-3, 2e-4, 2e-3]);
}
}

36
src/bin/lockin.rs
View File

@ -53,7 +53,7 @@ const APP: () = {
// Configure the microcontroller // Configure the microcontroller
let (mut stabilizer, _pounder) = hardware::setup(c.core, c.device); let (mut stabilizer, _pounder) = hardware::setup(c.core, c.device);
let pll = RPLL::new(ADC_SAMPLE_TICKS_LOG2 + SAMPLE_BUFFER_SIZE_LOG2, 0); let pll = RPLL::new(ADC_SAMPLE_TICKS_LOG2 + SAMPLE_BUFFER_SIZE_LOG2);
let lockin = Lockin::new( let lockin = Lockin::new(
&iir_int::IIRState::lowpass(1e-3, 0.707, 2.), // TODO: expose &iir_int::IIRState::lowpass(1e-3, 0.707, 2.), // TODO: expose
@ -119,30 +119,30 @@ const APP: () = {
let (pll_phase, pll_frequency) = c.resources.pll.update( let (pll_phase, pll_frequency) = c.resources.pll.update(
c.resources.timestamper.latest_timestamp().map(|t| t as i32), c.resources.timestamper.latest_timestamp().map(|t| t as i32),
22, // relative PLL frequency bandwidth: 2**-22, TODO: expose 23, // relative PLL frequency bandwidth: 2**-23, TODO: expose
22, // relative PLL phase bandwidth: 2**-22, TODO: expose 22, // relative PLL phase bandwidth: 2**-22, TODO: expose
); );
// Harmonic index of the LO: -1 to _de_modulate the fundamental // Harmonic index of the LO: -1 to _de_modulate the fundamental (complex conjugate)
let harmonic: i32 = -1; let harmonic: i32 = -1;
// Demodulation LO phase offset // Demodulation LO phase offset
let phase_offset: i32 = 0; let phase_offset: i32 = 0;
let sample_frequency = let sample_frequency = ((pll_frequency >> SAMPLE_BUFFER_SIZE_LOG2)
(pll_frequency >> SAMPLE_BUFFER_SIZE_LOG2).wrapping_mul(harmonic); as i32) // TODO: maybe rounding bias
let mut sample_phase = .wrapping_mul(harmonic);
let sample_phase =
phase_offset.wrapping_add(pll_phase.wrapping_mul(harmonic)); phase_offset.wrapping_add(pll_phase.wrapping_mul(harmonic));
for i in 0..adc_samples[0].len() { if let Some(output) = lockin.feed(
adc_samples[0].iter().map(|&i|
// Convert to signed, MSB align the ADC sample. // Convert to signed, MSB align the ADC sample.
let input = (adc_samples[0][i] as i16 as i32) << 16; (i as i16 as i32) << 16),
// Obtain demodulated, filtered IQ sample. sample_phase,
let output = lockin.update(input, sample_phase); sample_frequency,
// Advance the sample phase. ) {
sample_phase = sample_phase.wrapping_add(sample_frequency);
// Convert from IQ to power and phase. // Convert from IQ to power and phase.
let mut power = output.power() as _; let mut power = output.abs_sqr() as _;
let mut phase = output.phase() as _; let mut phase = output.arg() as _;
// Filter power and phase through IIR filters. // Filter power and phase through IIR filters.
// Note: Normalization to be done in filters. Phase will wrap happily. // Note: Normalization to be done in filters. Phase will wrap happily.
@ -153,11 +153,13 @@ const APP: () = {
// Note(unsafe): range clipping to i16 is ensured by IIR filters above. // Note(unsafe): range clipping to i16 is ensured by IIR filters above.
// Convert to DAC data. // Convert to DAC data.
for i in 0..dac_samples[0].len() {
unsafe { unsafe {
dac_samples[0][i] = dac_samples[0][i] =
power.to_int_unchecked::<i16>() as u16 ^ 0x8000; (power.to_int_unchecked::<i32>() >> 16) as u16 ^ 0x8000;
dac_samples[1][i] = dac_samples[1][i] =
phase.to_int_unchecked::<i16>() as u16 ^ 0x8000; (phase.to_int_unchecked::<i32>() >> 16) as u16 ^ 0x8000;
}
} }
} }
} }