Add NCO, DDS, and loop filter

.vscode/settings.json

@@ -1,7 +1,6 @@
 {
  "python.testing.pytestArgs": [
  "-c=pyproject.toml",
- "tests/"
  ],
  "python.testing.unittestEnabled": false,
  "python.testing.pytestEnabled": true,

README.md

@@ -21,5 +21,12 @@ A Python package for software-defined radio.
 
 ## Features
 
-- Filters: Infinite impulse response filters (`sdr.IIR`)
-- Arbitrary resamplers: Farrow resampler (`sdr.FarrowResampler`)
+- Filters:
+ - Infinite impulse response filter (`sdr.IIR`)
+- Arbitrary resamplers:
+ - Farrow resampler (`sdr.FarrowResampler`)
+- Signal generators:
+ - Numerically-controlled oscillator (`sdr.NCO`)
+ - Direct digital synthesizer (`sdr.DDS`)
+- Phase-locked loops:
+ - Loop filter (`sdr.LoopFilter`)

docs/api.rst

@@ -12,3 +12,8 @@ Resampling
 ----------
 
 .. python-apigen-group:: resampling
+
+Phase/time-locked loops
+-----------------------
+
+.. python-apigen-group:: pll

docs/examples/farrow-resampler.ipynb

@@ -30,7 +30,9 @@
  "cell_type": "markdown",
  "metadata": {},
  "source": [
- "## Construct an input signal, $x[n] = x(n T_s)$"
+ "## Construct an input signal, $x[n] = x(n T_s)$\n",
+ "\n",
+ "Create a discrete-time signal $x[n]$ that sample the continuous-time signal $x(t)$ at a sample rate $f_s = 1 / T_s$."
  ]
  },
  {
@@ -81,7 +83,12 @@
  "cell_type": "markdown",
  "metadata": {},
  "source": [
- "## Resample the input signal with rate $r$, $y[n] = x(n \\frac{T_s}{r})$"
+ "## Resample the input signal with rate $r$, $y[n] = x(n \\frac{T_s}{r})$\n",
+ "\n",
+ "Now, resample $x[n]$ such that the output $y[n]$ is equivalent to sampling the continuous-time $x(t)$\n",
+ "at sample rate $f_s = r/T_s$.\n",
+ "This is equivalent to sampling $x[n]$ at $1/r$ fractional samples.\n",
+ "This is accomplished, for arbitrary $r$, with a Farrow arbitrary resampler."
  ]
  },
  {

docs/index.rst

@@ -7,15 +7,23 @@ The :obj:`sdr` library is a Python 3 package for software-defined radio (SDR) ap
 Features
 --------
 
-- Filters: Infinite impulse response filters (:obj:`sdr.IIR`)
-- Arbitrary resamplers: Farrow resampler (:obj:`sdr.FarrowResampler`)
+- Filters:
+ - Infinite impulse response filter (:obj:`sdr.IIR`)
+- Arbitrary resamplers:
+ - Farrow resampler (:obj:`sdr.FarrowResampler`)
+- Signal generators:
+ - Numerically-controlled oscillator (:obj:`sdr.NCO`)
+ - Direct digital synthesizer (:obj:`sdr.DDS`)
+- Phase-locked loops:
+ - Loop filter (:obj:`sdr.LoopFilter`)
 
 .. toctree::
  :caption: Examples
  :hidden:
 
- examples/iir-filters.ipynb
+ examples/iir-filter.ipynb
  examples/farrow-resampler.ipynb
+ examples/phase-locked-loop.ipynb
 
 .. toctree::
  :caption: API Reference

pyproject.toml

@@ -109,6 +109,7 @@ disable = [
  "too-many-instance-attributes",
  "too-many-lines",
  "too-many-locals",
+ "too-many-public-methods",
  "unneeded-not",
 ]
 min-similarity-lines = 100

requirements-dev.txt

@@ -1,5 +1,5 @@
 pylint >= 2.14
-black >= 22.8.0
+black[jupyter] >= 22.8.0
 pytest
 pytest-cov[toml]
 pytest-xdist

src/sdr/__init__.py

@@ -15,3 +15,5 @@
 
 from ._farrow import FarrowResampler
 from ._iir_filter import IIR
+from ._loop_filter import LoopFilter
+from ._nco import DDS, NCO