Abstract
The pack measures, with its own cycle counter, the time from a block’s last bit coming off its own radio (“air”) to the moment the output stage takes that block for the DAC (“take”). It averages this air-to-take time over each 0.5 s look. A slow loop trims the pack’s own DAC master clock so that the mean air-to-take time stays at a fixed setpoint configured at build time (315 µs on the bench pack; plus 100 µs on a two-radio pack), with a ±10 µs dead band, a feed-forward of the clock difference fitted from the drift, and a guard that slows the clock when the slack before a take gets close to zero. The actuator is a fractional divider on the DAC master clock (by default), or the codec’s PLL, or the RT1062 audio PLL’s numerator: a frequency trim, not a resampler. At start-up and after every resync the output is held silent. The pack measures the air-to-take time, inserts whole silent blocks if it is short and drops DAC frames if it is long, up to four rounds, then releases the output with a fade-in. Steps are taken only while nothing is heard. No transmitter timestamp, no clock phase sent over the air and no feedback to the transmitter are used. The only reference is when the pack’s own radio delivered each block.
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Recommended Citation
Anonymous, "Receiver audio clock trimmed to hold a fixed, locally measured time from a block's arrival on air to its take by the output, with silent output during start and resync steps", Technical Disclosure Commons, ()
https://www.tdcommons.org/dpubs_series/12137