Add ratio conversions

.vscode/settings.json

@@ -18,38 +18,67 @@
     ],
     "cSpell.words": [
         "Albersheim",
+        "Alouini",
+        "arange",
+        "arcsin",
+        "astype",
+        "atleast",
         "awgn",
         "baseband",
+        "beamwidth",
+        "BPSK",
         "correlator",
+        "cumsum",
         "downsample",
         "downsampled",
         "downsamples",
         "downsampling",
+        "dtype",
         "exponentials",
         "feedforward",
         "figsize",
+        "frombuffer",
         "hexdump",
         "intersymbol",
+        "isrealobj",
+        "issubdtype",
+        "linestyle",
+        "linewidth",
         "lowpass",
+        "mathbb",
         "matplotlib",
         "multirate",
+        "ndarray",
+        "ndim",
+        "newaxis",
         "Nyquist",
         "overdamped",
+        "packbits",
+        "PAPR",
         "passband",
         "periodogram",
         "periodograms",
         "polyphase",
+        "Proakis",
         "pyplot",
         "QPSK",
         "resampler",
         "resamplers",
         "savefig",
         "scipy",
+        "sidelobes",
         "sinc",
         "stopband",
+        "unaliased",
         "underdamped",
+        "unpackbits",
         "upsampled",
         "upsamples",
-        "upsampling"
+        "upsampling",
+        "xlabel",
+        "xlim",
+        "ylabel",
+        "ylim",
+        "Zadoff"
     ]
 }

docs/api/conversions.rst

@@ -6,6 +6,11 @@ Decibels
 
 .. python-apigen-group:: conversions-decibels
 
+Ratios
+------
+
+.. python-apigen-group:: conversions-ratios
+
 From $E_b/N_0$
 --------------
 

src/sdr/_conversion.py

@@ -136,6 +136,104 @@ def linear(
     raise ValueError(f"Argument 'type' must be 'value', 'power', or 'voltage', not {type!r}.")
 
 
+##############################################################################
+# Ratios
+##############################################################################
+
+
+@export
+def percent(x: npt.ArrayLike) -> np.ndarray:
+    r"""
+    Converts from a ratio to a percentage.
+
+    Arguments:
+        x: The input ratio.
+
+    Returns:
+        The percentage.
+
+    Examples:
+        Convert 0.5 to 50%.
+
+        .. ipython:: python
+
+            sdr.percent(0.5)
+
+        Convert 0.25 to 25%.
+
+        .. ipython:: python
+
+            sdr.percent(0.25)
+
+    Group:
+        conversions-ratios
+    """
+    x = np.asarray(x)
+    return 100 * x
+
+
+@export
+def ppm(x: npt.ArrayLike) -> np.ndarray:
+    r"""
+    Converts from a ratio to parts per million (ppm).
+
+    Arguments:
+        x: The input ratio.
+
+    Returns:
+        The parts per million (ppm).
+
+    Examples:
+        Convert 0.005 to 5000 ppm.
+
+        .. ipython:: python
+
+            sdr.ppm(0.005)
+
+        Convert 0.000025 to 25 ppm.
+
+        .. ipython:: python
+
+            sdr.ppm(0.000025)
+
+    Group:
+        conversions-ratios
+    """
+    x = np.asarray(x)
+    return 1e6 * x
+
+
+@export
+def ppb(x: npt.ArrayLike) -> np.ndarray:
+    r"""
+    Converts from a ratio to parts per billion (ppb).
+
+    Arguments:
+        x: The input ratio.
+
+    Returns:
+        The parts per billion (ppb).
+
+    Examples:
+        Convert 0.000005 to 5000 ppb.
+
+        .. ipython:: python
+
+            sdr.ppb(0.000005)
+
+        Convert 0.000000025 to 25 ppb.
+
+        .. ipython:: python
+
+            sdr.ppb(0.000000025)
+
+    Group:
+        conversions-ratios
+    """
+    x = np.asarray(x)
+    return 1e9 * x
+
+
 ##############################################################################
 # From Eb/N0
 ##############################################################################

src/sdr/_link_budget/_antenna.py

@@ -14,7 +14,7 @@
 @export
 def wavelength(freq: float) -> float:
     r"""
-    Calculates the wavelength $\lambda$ of a electromagnetic wave with frequency $f$.
+    Calculates the wavelength $\lambda$ of an electromagnetic wave with frequency $f$.
 
     $$\lambda = \frac{c}{f}$$
 

tests/conversions/test_percent.py

@@ -0,0 +1,15 @@
+import numpy as np
+
+import sdr
+
+
+def test_0_5():
+    assert sdr.percent(0.5) == 50
+
+
+def test_0_25():
+    assert sdr.percent(0.25) == 25
+
+
+def test_array():
+    assert np.array_equal(sdr.percent(np.array([0.5, 0.25])), np.array([50, 25]))

tests/conversions/test_ppb.py

@@ -0,0 +1,15 @@
+import numpy as np
+
+import sdr
+
+
+def test_0_00005():
+    assert sdr.ppb(0.000005) == 5000
+
+
+def test_0_00000025():
+    assert sdr.ppb(0.000000025) == 25
+
+
+def test_array():
+    assert np.array_equal(sdr.ppb(np.array([0.000005, 0.000000025])), np.array([5000, 25]))

tests/conversions/test_ppm.py

@@ -0,0 +1,15 @@
+import numpy as np
+
+import sdr
+
+
+def test_0_005():
+    assert sdr.ppm(0.005) == 5000
+
+
+def test_0_000025():
+    assert sdr.ppm(0.000025) == 25
+
+
+def test_array():
+    assert np.array_equal(sdr.ppm(np.array([0.005, 0.000025])), np.array([5000, 25]))