Fix QPSK encoder for Python 3 compatibility#1
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Python 2→3 migration: symbol_stream / 2 became float division, corrupting the QPSK constellation (values -1,0,1,2 instead of ±1). Produced ~20% sample clipping vs ~12% correct, making firmware WAVs unreliable to flash. Fix: use // operator. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
qpsk/encoder.py:symbol_stream / 2uses float division in Python 3, corrupting the QPSK modulation constellation. Values that should be ±1 become -1, 0, 1, 2 — producing ~20% sample clipping (vs ~12% with correct encoding) and making firmware WAVs unreliable or impossible to flash via the audio bootloader.//(integer division) operator.byteshandling, removal ofLsuffixes,xrange→range, etc.Context
Discovered while building custom Clouds firmware and failing to flash via audio bootloader. The official firmware WAVs (generated with Python 2) worked fine, but locally-generated WAVs (Python 3) consistently failed with red blinking error LEDs on the module. Root cause traced to the corrupted QPSK constellation from float division.
The 4ms fork independently worked around this with
.astype(int)but never submitted upstream.Test plan