Dataflow

The WhisperTrack acoustic modem implements a bidirectional data flow for underwater communication between a ship-side system and the transducer.

Ship-Side System

The external system that generates acoustic signals for underwater communication with the modem.

Transducer

Converts between acoustic signals and electrical signals. Receives acoustic waves from the ship and converts them to electrical signals for processing, and converts electrical signals to acoustic waves for transmission.

Rx DMA Driver

Captures the digitized 1-bit signal from the comparator at 64 kHz. Packs 32 single-bit samples into 32-bit words using circular DMA transfers. Signals the Fontus processor when half or full buffers are ready.

Decode

Processes the raw digital samples through the Fontus RX state machine. Performs wake detection, doppler measurement, matched filtering, and demodulation to extract the message data.

Fontus Acoustic Message Processing

Core modem engine that implements the Fontus acoustic protocol. Contains the process data logic, hardware I/O interfaces, and Fontus bitfield structures for message handling. More details can be found on the Fontus Acoustic Messages page.

Encode

Implements the Fontus TX state machine to generate wake chirps, doppler chirps, and BFSK-modulated data as 16-bit PCM samples.

Tx DMA Driver

Transfers the encoded waveform data to the DAC at 64 kHz using timer-triggered DMA. Manages transmit buffer for complete message transmission.

Flow Diagram