From c050576b05a72fde64f8296c9ff110d784843be4 Mon Sep 17 00:00:00 2001
From: Oscar Gustafsson <oscar.gustafsson@gmail.com>
Date: Mon, 24 Apr 2023 09:57:50 +0200
Subject: [PATCH] Add Upsample and Downsample signal generators
---
b_asic/signal_generator.py | 78 ++++++++++++++++++++++++++++++++++-
test/test_signal_generator.py | 60 +++++++++++++++++++++++++++
2 files changed, 137 insertions(+), 1 deletion(-)
diff --git a/b_asic/signal_generator.py b/b_asic/signal_generator.py
index ec3ceb6b..e9bc99b4 100644
--- a/b_asic/signal_generator.py
+++ b/b_asic/signal_generator.py
@@ -13,7 +13,7 @@ if you want more information.
from math import pi, sin
from numbers import Number
-from typing import Optional, Sequence
+from typing import Optional, Sequence, Union
import numpy as np
@@ -408,3 +408,79 @@ class _DivGenerator(SignalGenerator):
else f"{self._b}"
)
return f"{a} / {b}"
+
+
+class Upsample(SignalGenerator):
+ """
+ Signal generator that upsamples the value of a signal generator or a sequence.
+
+ *factor* - 1 zeros are inserted between every value. If a sequence, it will
+ automatically be zero-padded.
+
+ Parameters
+ ----------
+ data : SignalGenerator or 1-D array
+ The signal generator or array to upsample.
+ factor : int
+ Upsampling factor.
+ phase : int, default 0
+ The phase of the upsampling.
+ """
+
+ def __init__(
+ self,
+ data: Union[SignalGenerator, Sequence[complex]],
+ factor: int,
+ phase: int = 0,
+ ) -> None:
+ if not isinstance(data, SignalGenerator):
+ data = ZeroPad(data)
+ self._generator = data
+ self._factor = factor
+ self._phase = phase
+
+ def __call__(self, time: int) -> complex:
+ index = (time - self._phase) / self._factor
+ if int(index) == index:
+ return self._generator(int(index))
+ else:
+ return 0.0
+
+ def __repr__(self) -> str:
+ return f"Upsample({self._generator!r}, {self._factor}, {self._phase})"
+
+
+class Downsample(SignalGenerator):
+ """
+ Signal generator that downsamples the value of a signal generator or a sequence.
+
+ Return every *factor*:th value. If a sequence, it will automatically be zero-padded.
+
+ Parameters
+ ----------
+ data : SignalGenerator or 1-D array
+ The signal generator or array to downsample.
+ factor : int
+ Downsampling factor.
+ phase : int, default 0
+ The phase of the downsampling.
+ """
+
+ def __init__(
+ self,
+ data: Union[SignalGenerator, Sequence[complex]],
+ factor: int,
+ phase: int = 0,
+ ) -> None:
+ if not isinstance(data, SignalGenerator):
+ data = ZeroPad(data)
+ self._generator = data
+ self._factor = factor
+ self._phase = phase
+
+ def __call__(self, time: int) -> complex:
+ index = time * self._factor + self._phase
+ return self._generator(index)
+
+ def __repr__(self) -> str:
+ return f"Downsample({self._generator!r}, {self._factor}, {self._phase})"
diff --git a/test/test_signal_generator.py b/test/test_signal_generator.py
index 787bf0d3..65266a25 100644
--- a/test/test_signal_generator.py
+++ b/test/test_signal_generator.py
@@ -5,12 +5,14 @@ import pytest
from b_asic.signal_generator import (
Constant,
Delay,
+ Downsample,
FromFile,
Gaussian,
Impulse,
Sinusoid,
Step,
Uniform,
+ Upsample,
ZeroPad,
_AddGenerator,
_DivGenerator,
@@ -284,3 +286,61 @@ def test_fromfile(datadir):
with pytest.raises(ValueError, match="could not convert string"):
g = FromFile(datadir.join('bad.csv'))
+
+
+def test_upsample():
+ g = Upsample([0.4, 0.6], 2)
+ assert g(-1) == 0
+ assert g(0) == 0.4
+ assert g(1) == 0
+ assert g(2) == 0.6
+ assert g(3) == 0.0
+
+ assert str(g) == "Upsample(ZeroPad([0.4, 0.6]), 2, 0)"
+
+ g = Upsample([0.4, 0.6], 2, 1)
+ assert g(-1) == 0
+ assert g(0) == 0.0
+ assert g(1) == 0.4
+ assert g(2) == 0.0
+ assert g(3) == 0.6
+ assert g(4) == 0.0
+
+ assert str(g) == "Upsample(ZeroPad([0.4, 0.6]), 2, 1)"
+
+ g = Upsample([0.4, 0.6], 3)
+ assert g(-1) == 0.0
+ assert g(0) == 0.4
+ assert g(1) == 0.0
+ assert g(2) == 0.0
+ assert g(3) == 0.6
+ assert g(4) == 0.0
+
+ assert str(g) == "Upsample(ZeroPad([0.4, 0.6]), 3, 0)"
+
+ g = Upsample(Sinusoid(0.5, 0.25), 3)
+ assert g(0) == pytest.approx(sqrt(2) / 2)
+ assert g(1) == 0.0
+ assert g(2) == 0.0
+ assert g(3) == pytest.approx(sqrt(2) / 2)
+ assert g(4) == 0.0
+ assert g(5) == 0.0
+ assert g(6) == pytest.approx(-sqrt(2) / 2)
+
+ assert str(g) == "Upsample(Sinusoid(0.5, 0.25), 3, 0)"
+
+
+def test_downsample():
+ g = Downsample([0.4, 0.6], 2)
+ assert g(-1) == 0
+ assert g(0) == 0.4
+ assert g(1) == 0.0
+ assert g(2) == 0.0
+ assert str(g) == "Downsample(ZeroPad([0.4, 0.6]), 2, 0)"
+
+ g = Downsample([0.4, 0.6], 2, 1)
+ assert g(-1) == 0
+ assert g(0) == 0.6
+ assert g(1) == 0.0
+ assert g(2) == 0.0
+ assert str(g) == "Downsample(ZeroPad([0.4, 0.6]), 2, 1)"
--
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