lockin: cleanup

Cargo.lock

@@ -348,8 +348,7 @@ dependencies = [
  "criterion",
  "libm",
  "ndarray",
- "ndarray-stats",
+ "rand",
- "rand 0.8.3",
  "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_chacha",
- "rand_core 0.6.1",
+ "rand_core",
- "rand_hc 0.3.0",
+ "rand_hc",
-]
-
-[[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",
 ]
 
 [[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",
+ "rand_core",
-]
-
-[[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",
 ]
 
 [[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",
+ "getrandom",
-]
-
-[[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",
 ]
 
 [[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"

dsp/Cargo.toml

@@ -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"

dsp/src/lockin.rs

@@ -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
-    }
-}

dsp/src/rpll.rs

@@ -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]