A Digital Audio Transceiver is a system which is compatible with the digtal audio transmission standards supported by CD players, RDAT recorders, professional recording and broadcasting equipments, audio workstations, etc. A functional block diagram of the Motorola DSP56401 Digital Audio Transceiver is shown in fig. 6. It is a single chip consisting of an independent transmitter and receiver with common clock generator and control logic, transmit and receive serial inteface, all independent and asynchronous to each other.. It can be directly connected to the serial port of DSPs, DACs, ADCs or microprocessors and to the audio I/O ports of standard digital audio devices.
Fig. 6 - Motorola DSP56401 AES/EBU/CP-340 Digital Audio Transceiver functional block diagram
A block diagram of the digital audio modulator is shown in fig. 7. The modulator produces an LSB first, serial data output compatible with the AES/EBU/CP-340 digital audio transmission standard. The modulator state machine generates preambles, parity and optionally, CRC informations which are added to the frame of the sample data and non audio data received from the transmit serial interface.
Fig. 7 - Motorola DSP56401 AES/EBU/CP-340 Digital Audio Transceiver Digital Audio Modulator.
A block diagram of the digital audio demodulator is shown in fig. 8. The demodulator produces an LSB first, serial data output compatible with the AES/EBU/CP-340 digital audio transmission standard. The demodulator PLL recovers a bit clock from the demodulated serial input. The demodulator state machine detects preamble sync patterns, parity errors and CRC errors, and separates the audio sample data from the non audio data. The separated data is converted to MSB first representation during a parallel transfer once per frame to the receive serial interface.
Fig. 8 - Motorola DSP56401 AES/EBU/CP-340 Digital Audio Transceiver Digital Audio Demodulator.
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