Abstract
The transmitter sends a never-ending bit stream: a back-to-back sequence of fixed blocks (330 bits, 3000 a second in the embodiment), each carrying its own sync word and a sequence ("period") field in band, then its payload and a few guard bits. There are no packet headers and no gaps; control messages ride inside the blocks.
The stream enters and leaves the radio by one of three paths:
1. Synchronous direct mode. The radio clocks bits to and from the host on a data line and a clock line. On the Si4463 (4-GFSK) raw receive became bit-exact once the AFC's feedback to the synthesiser was disabled; on the EFR32ZG28 (2-GFSK) it became bit-exact at 1 and 2 Mb/s.
2. Asynchronous direct output plus host clock recovery. Where a demodulator gives bit decisions but no clock, a bang-bang digital PLL in the host's programmable I/O re-times the data: 0 errors in 120 Mbit at 2 Mb/s.
3. Infinite-length FIFO stream. Where there is no direct-mode receive path, the radio sends one packet with no length limit and no CRC: one preamble and sync word at the start, then the stream for as long as the link runs, its FIFOs serviced over SPI on the same two host lines.
In every path a host port counts the radio's clock edges, and a software deframer finds, confirms and tracks block boundaries and recovers the absolute period.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Anonymous, "Continuous low-latency audio stream through a transceiver's direct mode or an infinite-length FIFO stream: in-band framed fixed blocks, no packet headers or gaps, a host deframer clocked by the radio, and host clock recovery for asynchronous demodulator output (second version)", Technical Disclosure Commons, (October 20, 2026)
https://www.tdcommons.org/dpubs_series/12311