Ryan Malloy
0ee7ff0ad7
Complete signal processing pipeline from complex baseband to decoded PCM telemetry, verified against the 1965 NAA Study Guide (A-624): Core demod (Phase 1): - PM demodulator with carrier PLL recovery - 1.024 MHz subcarrier extractor (bandpass + downconvert) - BPSK demodulator with Costas loop + symbol sync - Convenience hier_block2 combining subcarrier + BPSK PCM frame processing (Phase 2): - 32-bit frame sync with Hamming distance correlator - SEARCH/VERIFY/LOCKED state machine, complement-on-odd handling - Frame demultiplexer (128-word, A/D voltage scaling) - AGC downlink decoder (15-bit word reassembly from DNTM1/DNTM2) Voice and analog (Phase 3): - 1.25 MHz FM voice subcarrier demod to 8 kHz audio - SCO demodulator for 9 analog sensor channels (14.5-165 kHz) Virtual AGC integration (Phase 4): - TCP bridge client with auto-reconnect and channel filtering - DSKY uplink encoder (VERB/NOUN/DATA command sequences) Top-level receiver (Phase 5): - usb_downlink_receiver hier_block2: one block, complex in, PDUs out - 14 GRC block YAML definitions for GNU Radio Companion - Example scripts for signal analysis and full-chain demo Infrastructure: - constants.py with all timing/frequency/frame parameters - protocol.py for sync word + AGC packet encode/decode - Synthetic USB signal generator for testing - 222 tests passing, ruff lint clean
67 lines
2.0 KiB
Python
67 lines
2.0 KiB
Python
#!/usr/bin/env python3
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"""
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Apollo USB Downlink Demo — generate and decode synthetic telemetry.
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Demonstrates the full gr-apollo demod chain:
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1. Generate a synthetic USB baseband signal with known PCM frames
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2. Feed it through usb_downlink_receiver (all-in-one block)
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3. Print decoded frames as they arrive
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Usage:
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uv run python examples/usb_downlink_demo.py
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"""
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import numpy as np
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from gnuradio import blocks, gr
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from apollo.constants import SAMPLE_RATE_BASEBAND
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from apollo.usb_downlink_receiver import usb_downlink_receiver
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from apollo.usb_signal_gen import generate_usb_baseband
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def main():
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np.random.seed(42)
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known_payload = bytes(np.random.randint(0, 256, size=124, dtype=np.uint8))
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print("Generating 5-frame synthetic USB baseband signal...")
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signal, frame_bits = generate_usb_baseband(
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frames=5,
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frame_data=[known_payload] * 5,
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snr_db=30.0, # 30 dB SNR — moderate noise
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)
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print(f" Signal: {len(signal)} samples, {len(signal)/SAMPLE_RATE_BASEBAND:.3f}s")
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print(f" Frames: {len(frame_bits)} x {len(frame_bits[0])} bits")
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print("\nBuilding flowgraph: usb_downlink_receiver...")
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tb = gr.top_block()
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src = blocks.vector_source_c(signal.tolist())
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receiver = usb_downlink_receiver(output_format="scaled")
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snk = blocks.message_debug()
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tb.connect(src, receiver)
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tb.msg_connect(receiver, "frames", snk, "store")
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print("Running flowgraph...")
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tb.run()
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n_frames = snk.num_messages()
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print(f"\nReceived {n_frames} frame(s) on 'frames' port")
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if n_frames > 0:
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print("\nFirst frame metadata:")
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import pmt
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msg = snk.get_message(0)
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meta = pmt.car(msg)
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fid = pmt.to_long(pmt.dict_ref(meta, pmt.intern("frame_id"), pmt.from_long(-1)))
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conf = pmt.to_long(pmt.dict_ref(meta, pmt.intern("sync_confidence"), pmt.from_long(-1)))
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print(f" frame_id: {fid}")
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print(f" sync_confidence: {conf}")
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else:
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print("No frames decoded (PLL may need more settling time)")
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if __name__ == "__main__":
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main()
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