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
59 lines
1.5 KiB
YAML
59 lines
1.5 KiB
YAML
id: apollo_pcm_frame_sync
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label: Apollo PCM Frame Sync
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category: '[Apollo USB]'
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flags: [python]
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parameters:
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- id: bit_rate
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label: Bit Rate (bps)
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dtype: int
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default: '51200'
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options: ['51200', '1600']
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option_labels: ['High (51.2 kbps)', 'Low (1.6 kbps)']
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- id: max_bit_errors
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label: Max Sync Bit Errors
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dtype: int
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default: '3'
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inputs:
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- label: in
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domain: stream
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dtype: byte
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outputs:
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- label: frames
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domain: message
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templates:
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imports: from apollo import pcm_frame_sync
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make: >-
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apollo.pcm_frame_sync.pcm_frame_sync(
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bit_rate=${bit_rate},
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max_bit_errors=${max_bit_errors})
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documentation: |-
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Apollo PCM Frame Synchronizer
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Acquires the 32-bit frame sync pattern from an NRZ bit stream and
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outputs complete PCM frames as PDU messages.
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The sync word format is:
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[5-bit A][15-bit core][6-bit B][6-bit frame ID]
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The 15-bit core is complemented on odd-numbered frames. The correlator
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checks against both patterns simultaneously using Hamming distance.
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State machine: SEARCH -> VERIFY -> LOCKED (back to SEARCH on N misses).
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Parameters:
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bit_rate: 51200 (128 words/frame, 50 fps) or 1600 (200 words/frame, 1 fps)
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max_bit_errors: Hamming distance threshold for sync detection (default 3)
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Output PDU metadata:
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frame_id: Frame number within subframe (1-50)
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odd_frame: True if odd frame (complemented core)
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sync_confidence: Number of correct sync bits (out of 32)
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timestamp: System time at frame detection
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file_format: 1
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