Ryan Malloy
86a5b08e9d
Implements the Apollo composite PRN ranging code (5,456,682 chips) from five component sequences (CL, X, A, B, C) combined via majority-vote logic, matching Ken Shirriff's Teensy rangeGenerator.ino bit-for-bit. LFSR taps corrected to produce maximal-length sequences: A: 5-bit, taps [2,0] (x^5+x^2+1, period 31) B: 6-bit, taps [1,0] (x^6+x+1, period 63) C: 7-bit, taps [1,0] (x^7+x+1, period 127) New files: src/apollo/ranging.py -- pure-Python code generator and correlator src/apollo/ranging_source.py -- GR sync_block streaming PRN chips src/apollo/ranging_mod.py -- GR hier_block2 NRZ chip modulator src/apollo/ranging_demod.py -- GR basic_block FFT-based range correlator grc/apollo_ranging_*.block.yml -- GRC block definitions (3 files) examples/ranging_demo.py -- standalone demo with delay simulation
31 lines
784 B
YAML
31 lines
784 B
YAML
id: apollo_ranging_source
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label: Apollo Ranging Source
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category: '[Apollo USB]'
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flags: [python]
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parameters: []
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outputs:
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- label: out
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domain: stream
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dtype: byte
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templates:
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imports: from apollo.ranging_source import ranging_source
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make: apollo.ranging_source.ranging_source()
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documentation: |-
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Apollo PRN Ranging Source
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Generates a continuous stream of PRN ranging code chips (bytes 0 or 1).
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The composite code combines CL, X, A, B, and C component sequences
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using majority-vote logic: output = (NOT(X) AND maj(A,B,C)) XOR CL
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Code length: 5,456,682 chips (~5.49 seconds at 993,963 chips/sec)
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The code repeats cyclically.
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The full code period is pre-generated at startup, so the first call
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has a brief delay while the sequence is computed.
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file_format: 1
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