fce14f038e
First transmission through a real radio path in the project. A 4756-byte JPEG went from transmitter to receiver over two antennas 60 cm apart at 225 MHz and reassembled byte-identical, reproduced across three runs. The cable loopback still needs an SMA male-to-male adapter that has not arrived, so this air run is a track verification, not the controlled measurement: room levels are not held the way a cable holds them. Its purpose was to exercise the device wrapper the models cannot cover. Four defects the software model passed but the hardware exposed, each reproduced and fixed: - a 566 528-sample frame did not fit the 262 144 receive buffer, and the sample stream is not continuous across separate reads, so a frame on the seam was destroyed. Reception now uses one buffer sized to the frame - carrier correction was always applied, but with a shared reference the true offset is near zero and the 80-symbol marker estimate is noise; correcting by it rotated phase along the whole frame, 65% bit errors measured. Ported should_apply_cfo_correction from Lab023 - receiver gain of 20 dB left the signal at 0.0003 of full scale. Levels set by measurement: RX 50 dB, TX -10 dB give zero bit errors with margin - the error-vector metric returned zero on a failed receive, reporting a perfect signal where there was none, the same class of defect as the written-in figures of Lab041. Replaced with an explicit not-computed value The air TX gain ceiling is now derived from the link budget by antenna distance rather than a constant. Three loopback modes: software, cable, air. PROJECT_LOG entry 019 records the run and the defects. Software and cable results stay reproducible; 125 tests pass, gate passes.
7.8 KiB
7.8 KiB