orion-sdr 0.0.33

DSP/SDR block library targeting HF-to-UHF, satellites, and Python bindings. Roadmap inside.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191

"""Roundtrip tests for the orion_sdr Python extension.

Analog tests modulate a tone, demodulate it, and assert that SNR in the
recovered audio exceeds a minimum threshold.

Digital tests perform noiseless bit-exact roundtrips through the full
mod/demod pipeline (mapper → waveform → demod → decider) and assert
perfect bit recovery.
"""

import numpy as np
import pytest

import orion_sdr as sdr
from .conftest import FS, real_tone, snr_db, tail


N = 32_768  # long enough for reliable SNR estimates after transient


# ---------------------------------------------------------------------------
# CW: CwKeyedMod → CwEnvelopeDemod
# ---------------------------------------------------------------------------

def test_roundtrip_cw_envelope():
    """Recovered keying envelope should have >14 dB ON/OFF contrast."""
    n = 24_000
    pitch_hz = 700.0
    key_f = 5.0  # 5 Hz square wave keying

    key_env = np.array(
        [(1.0 if (k * key_f / FS) % 1.0 < 0.5 else 0.0) for k in range(n)],
        dtype=np.float32,
    )

    iq = sdr.CwKeyedMod(FS, pitch_hz, 3.0, 3.0).process(key_env)
    audio = sdr.CwEnvelopeDemod(FS, pitch_hz, 300.0).process(iq)

    skip = int(0.100 * FS)
    a = audio[skip:]
    k = key_env[skip:]

    on_rms  = float(np.sqrt(np.mean(a[k > 0.5] ** 2)))
    off_rms = float(np.sqrt(np.mean(a[k < 0.5] ** 2))) + 1e-12
    contrast_db = 20.0 * np.log10(on_rms / off_rms)

    assert contrast_db > 14.0, f"CW ON/OFF contrast {contrast_db:.1f} dB < 14 dB"


# ---------------------------------------------------------------------------
# AM: AmDsbMod → AmEnvelopeDemod
# ---------------------------------------------------------------------------

def test_roundtrip_am_envelope():
    f_mod = 1_000.0
    audio_in = real_tone(FS, f_mod, N, 0.5)

    iq = sdr.AmDsbMod(FS, 0.0, 0.8, 0.5).process(audio_in)
    audio_out = sdr.AmEnvelopeDemod(FS, 5_000.0).process(iq)

    snr = snr_db(tail(audio_out), FS, f_mod)
    assert snr > 24.0, f"AM roundtrip SNR {snr:.1f} dB < 24 dB"


def test_roundtrip_am_envelope_abs_approx():
    """AbsApprox variant should also achieve acceptable SNR."""
    f_mod = 1_000.0
    audio_in = real_tone(FS, f_mod, N, 0.5)

    iq = sdr.AmDsbMod(FS, 0.0, 0.8, 0.5).process(audio_in)
    audio_out = sdr.AmEnvelopeDemod(FS, 5_000.0, abs_approx=True).process(iq)

    snr = snr_db(tail(audio_out), FS, f_mod)
    assert snr > 20.0, f"AM AbsApprox roundtrip SNR {snr:.1f} dB < 20 dB"


# ---------------------------------------------------------------------------
# SSB: SsbPhasingMod (USB) → SsbProductDemod
# ---------------------------------------------------------------------------

def test_roundtrip_ssb_usb():
    f_audio = 1_200.0
    audio_bw_hz = 2_800.0
    audio_if_hz = 1_500.0
    audio_in = real_tone(FS, f_audio, N, 0.4)

    iq = sdr.SsbPhasingMod(FS, audio_bw_hz, audio_if_hz, 0.0, True).process(audio_in)
    audio_out = sdr.SsbProductDemod(FS, audio_if_hz, audio_bw_hz).process(iq)

    skip = int(0.120 * FS)
    snr = snr_db(audio_out[skip:], FS, f_audio)
    assert snr > 18.0, f"SSB USB roundtrip SNR {snr:.1f} dB < 18 dB"


# ---------------------------------------------------------------------------
# FM: FmPhaseAccumMod → FmQuadratureDemod
# ---------------------------------------------------------------------------

def test_roundtrip_fm_quadrature():
    f_mod = 1_000.0
    audio_in = real_tone(FS, f_mod, N, 0.5)

    iq = sdr.FmPhaseAccumMod(FS, 2_500.0, 0.0).process(audio_in)
    audio_out = sdr.FmQuadratureDemod(FS, 2_500.0, 5_000.0).process(iq)

    snr = snr_db(tail(audio_out), FS, f_mod)
    assert snr > 20.0, f"FM roundtrip SNR {snr:.1f} dB < 20 dB"


# ---------------------------------------------------------------------------
# PM: PmDirectPhaseMod → PmQuadratureDemod
# ---------------------------------------------------------------------------

def test_roundtrip_pm_quadrature():
    f_mod = 900.0
    audio_in = real_tone(FS, f_mod, N, 0.5)

    iq = sdr.PmDirectPhaseMod(FS, 0.9, 0.0).process(audio_in)
    audio_out = sdr.PmQuadratureDemod(FS, 0.9, 5_000.0).process(iq)

    snr = snr_db(tail(audio_out), FS, f_mod)
    assert snr > 18.0, f"PM roundtrip SNR {snr:.1f} dB < 18 dB"


# ---------------------------------------------------------------------------
# BPSK: noiseless bit-exact roundtrip
# ---------------------------------------------------------------------------

def test_roundtrip_bpsk_noiseless():
    """BpskMod → BpskDemod must recover bits perfectly in a noiseless channel."""
    n = 256
    bits_in = np.array([i & 1 for i in range(n)], dtype=np.uint8)

    iq = sdr.BpskMod(1.0, 0.0, 1.0).process(bits_in)
    bits_out = sdr.BpskDemod(1.0).process(iq)

    assert iq.shape == (n,) and iq.dtype == np.complex64
    assert bits_out.shape == (n,) and bits_out.dtype == np.uint8
    np.testing.assert_array_equal(bits_in, bits_out)


# ---------------------------------------------------------------------------
# QPSK: mapper symbol check + noiseless roundtrip
# ---------------------------------------------------------------------------

def test_qpsk_mapper_symbols():
    """Check all four constellation points against expected normalized values."""
    S = float(np.sqrt(0.5))  # 1/√2
    # dibits: (0,0)→(+S,+S), (0,1)→(+S,−S), (1,0)→(−S,+S), (1,1)→(−S,−S)
    bits = np.array([0,0, 0,1, 1,0, 1,1], dtype=np.uint8)
    iq = sdr.QpskMod(1.0, 0.0, 1.0).process(bits)
    assert iq.shape == (4,)
    expected = np.array([S+1j*S, S-1j*S, -S+1j*S, -S-1j*S], dtype=np.complex64)
    np.testing.assert_allclose(iq, expected, atol=1e-6)


def test_roundtrip_qpsk_noiseless():
    n_syms = 256
    # interleave 0/1 bits so all dibits appear
    bits_in = np.array([(i // 2 + i) & 1 for i in range(n_syms * 2)], dtype=np.uint8)

    iq = sdr.QpskMod(1.0, 0.0, 1.0).process(bits_in)
    bits_out = sdr.QpskDemod(1.0).process(iq)

    assert iq.shape == (n_syms,) and iq.dtype == np.complex64
    assert bits_out.shape == (n_syms * 2,) and bits_out.dtype == np.uint8
    np.testing.assert_array_equal(bits_in, bits_out)


# ---------------------------------------------------------------------------
# QAM-16/64/256: noiseless roundtrip for each order
# ---------------------------------------------------------------------------

@pytest.mark.parametrize("order,bits_per_sym", [(16, 4), (64, 6), (256, 8)])
def test_roundtrip_qam_noiseless(order, bits_per_sym):
    """QamMod(order) → QamDemod(order) must recover bits perfectly."""
    n_syms = 256
    n_bits = n_syms * bits_per_sym
    # cycle bits to exercise all symbol values
    bits_in = np.array([(i // bits_per_sym + i % bits_per_sym) & 1
                        for i in range(n_bits)], dtype=np.uint8)

    iq = sdr.QamMod(order, 1.0, 0.0, 1.0).process(bits_in)
    bits_out = sdr.QamDemod(order, 1.0).process(iq)

    assert iq.shape == (n_syms,) and iq.dtype == np.complex64
    assert bits_out.shape == (n_bits,) and bits_out.dtype == np.uint8
    np.testing.assert_array_equal(
        bits_in, bits_out,
        err_msg=f"QAM-{order} noiseless roundtrip failed"
    )