Lab042 cannot reuse the DSP from the earlier labs the way its
specification assumed. Three blockers turned up on inspection:
- importing lab018, lab019 or lab023 creates directories and writes .npy,
.png and report files at module level, so importing them silently
re-runs their experiments
- build_radio_frame() takes no arguments and encodes a fixed text message
- decode_radio_frame() returns a status string rather than the payload
So the verified primitives move into a module that is safe to import and
does no work of its own. Function bodies are carried over verbatim, and
the source lab is named above each one:
- from Lab023: bytes_to_bits, bits_to_bytes, bpsk_modulate,
bpsk_demodulate, estimate_carrier_parameters, correct_phase_and_frequency
- from Lab019: build_frame_marker, find_radio_frame
- from Lab018: root_raised_cosine_taps
build_radio_frame and parse_radio_frame are written fresh here to carry
arbitrary payloads; the on-air structure is unchanged, still preamble,
sync word, length, packet.
Verified against the originals by loading their function definitions in
isolation and comparing outputs: 31 comparisons, no divergence, including
the CFO estimator over random phase and frequency offsets.
End-to-end check with no hardware: a 5828-byte JPEG through fragments,
packets, frames, shaping at 128 samples per symbol and matched filtering
recovers 12 of 12 fragments and reassembles byte-identical.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
