Complete VIDEO-001 through VIDEO-004 software video studies

tests/test_video003_modem.py

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+"""Эталонные векторы и строгий приём программного QPSK VIDEO-003."""
+
+from __future__ import annotations
+
+import math
+
+import numpy as np
+import pytest
+
+from protocol import punctured_fec
+from protocol.video003_modem import (
+    PREAMBLE_SYMBOLS,
+    build_frame,
+    known_preamble_bits,
+    qpsk_soft,
+    qpsk_symbols,
+    receive_frame,
+    rrc_roundtrip,
+    samples_per_symbol,
+)
+
+
+def test_gray_mapping_known_vector_and_unit_energy() -> None:
+    bits = np.array([0, 0, 0, 1, 1, 1, 1, 0], dtype=np.uint8)
+    expected = np.array([-1-1j, -1+1j, 1+1j, 1-1j]) / math.sqrt(2)
+    assert np.allclose(qpsk_symbols(bits), expected)
+    assert np.allclose(np.abs(expected) ** 2, 1.0)
+    assert np.array_equal((qpsk_soft(expected) >= 0).astype(np.uint8), bits)
+    pairs = bits.reshape(4, 2)
+    assert all(np.count_nonzero(pairs[index] != pairs[(index + 1) % 4]) == 1
+               for index in range(4))
+
+
+def test_preamble_matches_lab043_reference() -> None:
+    from experiments.lab043_pluto_to_rtlsdr import pilot_prbs7
+
+    assert np.array_equal(known_preamble_bits(), pilot_prbs7(PREAMBLE_SYMBOLS, 0x7F))
+
+
+@pytest.mark.parametrize("rate", ["1/2", "2/3", "3/4"])
+def test_puncturing_preserves_existing_code_and_decodes_without_noise(rate: str) -> None:
+    random_generator = np.random.default_rng(3303)
+    for size in (1, 13, 256, 1012):
+        bits = random_generator.integers(0, 2, size * 8, dtype=np.uint8)
+        coded = punctured_fec.encode(bits, rate)
+        assert len(coded) == punctured_fec.coded_bit_count(len(bits), rate)
+        restored = punctured_fec.decode_soft(2.0 * coded - 1.0, len(bits), rate)
+        assert np.array_equal(restored, bits)
+        assert punctured_fec.effective_rate(len(bits), rate) < float(rate[0]) / float(rate[2])
+
+
+def test_puncturing_patterns_and_erasure_locations() -> None:
+    assert punctured_fec.PUNCTURE_PATTERNS == {
+        "1/2": (1, 1), "2/3": (1, 1, 1, 0), "3/4": (1, 1, 1, 0, 0, 1)
+    }
+    values = np.arange(punctured_fec.coded_bit_count(8, "2/3"), dtype=float) + 1
+    restored = punctured_fec.depuncture_soft(values, 8, "2/3")
+    assert np.array_equal(restored[3::4], np.zeros(len(restored[3::4])))
+    with pytest.raises(ValueError):
+        punctured_fec.depuncture_soft(values[:-1], 8, "2/3")
+
+
+@pytest.mark.parametrize("modulation,symbol_rate", [
+    ("BPSK", 500_000), ("QPSK", 250_000), ("QPSK", 500_000)
+])
+@pytest.mark.parametrize("rate", ["1/2", "2/3", "3/4"])
+def test_independent_receive_phase_quadrant_and_cfo(
+    modulation: str, symbol_rate: int, rate: str
+) -> None:
+    payload = bytes(range(48))
+    frame = build_frame(payload, modulation, rate)
+    indexes = np.arange(len(frame.symbols), dtype=float)
+    phase = 0.23 + (math.pi / 2 if modulation == "QPSK" else 0.0)
+    shifted = frame.symbols * np.exp(1j * (phase + 2 * math.pi * 73 * indexes / symbol_rate))
+    prefix = np.full(9, 0.1 + 0.2j)
+    outcome = receive_frame(np.concatenate((prefix, shifted)), modulation, rate, symbol_rate)
+    assert outcome.preamble_found and outcome.phy_header_pass and outcome.crc_pass
+    assert outcome.start_symbol == 9
+    assert outcome.payload == payload
+    assert outcome.frequency_offset_hz == pytest.approx(73, abs=0.1)
+
+
+@pytest.mark.parametrize("symbol_rate", [250_000, 500_000])
+def test_rrc_known_timing_preserves_qpsk_packet(symbol_rate: int) -> None:
+    frame = build_frame(b"RRC check", "QPSK", "2/3")
+    filtered = rrc_roundtrip(frame.symbols, symbol_rate)
+    result = receive_frame(filtered, "QPSK", "2/3", symbol_rate)
+    assert samples_per_symbol(symbol_rate) == 8_000_000 // symbol_rate
+    assert result.crc_pass and result.payload == b"RRC check"
+
+
+def test_corruption_and_truncation_cannot_become_crc_pass() -> None:
+    frame = build_frame(bytes(range(32)), "QPSK", "3/4")
+    truncated = receive_frame(frame.symbols[:-20], "QPSK", "3/4", 500_000)
+    assert truncated.preamble_found and truncated.phy_header_pass and not truncated.crc_pass
+    broken = frame.symbols.copy()
+    broken[PREAMBLE_SYMBOLS:PREAMBLE_SYMBOLS + 144] *= -1
+    rejected = receive_frame(broken, "QPSK", "3/4", 500_000)
+    assert rejected.preamble_found and not rejected.phy_header_pass and not rejected.crc_pass
+
+
+def test_full_packet_limit_is_enforced_before_modulation() -> None:
+    assert len(build_frame(bytes(1012), "QPSK", "3/4").packet) == 1024
+    with pytest.raises(ValueError, match="1024"):
+        build_frame(bytes(1013), "QPSK", "3/4")