Ryan Malloy
493c21c511
Implement the transmit/generate side as streaming GNU Radio blocks, complementing the existing receive chain. Each block maps to a physical instrument on CuriousMarc's Keysight bench: pcm_frame_source - PCM bit stream generator (sync_block + FrameSourceEngine) nrz_encoder - bits to NRZ waveform (+1/-1) with upsampling bpsk_subcarrier_mod - NRZ x cos(1.024 MHz) BPSK modulator fm_voice_subcarrier_mod - 1.25 MHz FM test tone source pm_mod - phase modulator: exp(j * deviation * input) usb_signal_source - convenience wrapper wiring all blocks together Includes GRC YAML definitions for all blocks under [Apollo USB] category, 49 new tests (271 total, all passing), and a loopback test that validates the full TX->RX round trip including frame recovery with 30 dB AWGN.
147 lines
4.6 KiB
Python
147 lines
4.6 KiB
Python
"""Tests for the PM modulator block."""
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import numpy as np
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import pytest
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try:
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from gnuradio import blocks, gr
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HAS_GNURADIO = True
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except ImportError:
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HAS_GNURADIO = False
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from apollo.constants import PM_PEAK_DEVIATION_RAD, SAMPLE_RATE_BASEBAND
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pytestmark = pytest.mark.skipif(not HAS_GNURADIO, reason="GNU Radio not installed")
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class TestPMMod:
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"""Test PM modulation with synthetic signals."""
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def test_zero_input_constant_envelope(self):
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"""Zero input should produce exp(j*0) = 1+0j (unit carrier)."""
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from apollo.pm_mod import pm_mod
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tb = gr.top_block()
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n_samples = 10000
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data = [0.0] * n_samples
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src = blocks.vector_source_f(data)
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mod = pm_mod(pm_deviation=PM_PEAK_DEVIATION_RAD, sample_rate=SAMPLE_RATE_BASEBAND)
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snk = blocks.vector_sink_c()
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tb.connect(src, mod, snk)
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tb.run()
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output = np.array(snk.data())
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assert len(output) == n_samples
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# Magnitude should be 1.0 (constant envelope)
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magnitudes = np.abs(output)
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np.testing.assert_allclose(magnitudes, 1.0, atol=1e-6)
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# Phase should be 0 (no modulation)
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phases = np.angle(output)
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np.testing.assert_allclose(phases, 0.0, atol=1e-6)
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def test_sine_input_phase_deviation(self):
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"""Sine wave input should produce phase swinging +/- pm_deviation."""
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from apollo.pm_mod import pm_mod
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tb = gr.top_block()
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n_samples = 100000
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sample_rate = SAMPLE_RATE_BASEBAND
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# Unit-amplitude sine at 10 kHz as modulating signal
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t = np.arange(n_samples, dtype=np.float64) / sample_rate
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tone_freq = 10000.0
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modulating = np.sin(2 * np.pi * tone_freq * t).astype(np.float32)
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src = blocks.vector_source_f(modulating.tolist())
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mod = pm_mod(pm_deviation=PM_PEAK_DEVIATION_RAD, sample_rate=sample_rate)
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snk = blocks.vector_sink_c()
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tb.connect(src, mod, snk)
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tb.run()
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output = np.array(snk.data())
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phases = np.angle(output)
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# Peak phase should be approximately pm_deviation
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peak_phase = np.max(np.abs(phases))
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assert peak_phase == pytest.approx(PM_PEAK_DEVIATION_RAD, abs=0.01), (
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f"Peak phase {peak_phase} doesn't match deviation {PM_PEAK_DEVIATION_RAD}"
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)
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def test_constant_envelope(self):
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"""PM output should always have |s(t)| = 1.0 regardless of input."""
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from apollo.pm_mod import pm_mod
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tb = gr.top_block()
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n_samples = 50000
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sample_rate = SAMPLE_RATE_BASEBAND
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# Arbitrary varying input: sum of two tones
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t = np.arange(n_samples, dtype=np.float64) / sample_rate
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modulating = (
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0.7 * np.sin(2 * np.pi * 5000 * t) + 0.3 * np.cos(2 * np.pi * 20000 * t)
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).astype(np.float32)
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src = blocks.vector_source_f(modulating.tolist())
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mod = pm_mod(pm_deviation=PM_PEAK_DEVIATION_RAD, sample_rate=sample_rate)
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snk = blocks.vector_sink_c()
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tb.connect(src, mod, snk)
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tb.run()
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output = np.array(snk.data())
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magnitudes = np.abs(output)
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np.testing.assert_allclose(magnitudes, 1.0, atol=1e-6)
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def test_custom_deviation(self):
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"""Custom pm_deviation should scale output phase accordingly."""
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from apollo.pm_mod import pm_mod
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tb = gr.top_block()
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n_samples = 100000
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sample_rate = SAMPLE_RATE_BASEBAND
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custom_dev = 0.5
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# Unit-amplitude sine
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t = np.arange(n_samples, dtype=np.float64) / sample_rate
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tone_freq = 10000.0
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modulating = np.sin(2 * np.pi * tone_freq * t).astype(np.float32)
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src = blocks.vector_source_f(modulating.tolist())
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mod = pm_mod(pm_deviation=custom_dev, sample_rate=sample_rate)
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snk = blocks.vector_sink_c()
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tb.connect(src, mod, snk)
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tb.run()
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output = np.array(snk.data())
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phases = np.angle(output)
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peak_phase = np.max(np.abs(phases))
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assert peak_phase == pytest.approx(custom_dev, abs=0.02), (
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f"Peak phase {peak_phase} doesn't match custom deviation {custom_dev}"
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)
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def test_block_instantiation(self):
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"""Block should instantiate with default parameters."""
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from apollo.pm_mod import pm_mod
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mod = pm_mod()
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assert mod is not None
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assert mod.get_pm_deviation() == PM_PEAK_DEVIATION_RAD
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def test_set_pm_deviation(self):
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"""Runtime deviation update should take effect."""
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from apollo.pm_mod import pm_mod
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mod = pm_mod()
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assert mod.get_pm_deviation() == PM_PEAK_DEVIATION_RAD
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mod.set_pm_deviation(0.25)
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assert mod.get_pm_deviation() == 0.25
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