MX826

The MX826 is a mProcessor controlled full-duplex audio processor on a single-chip with separate TX and RX paths to provide all the filter/gain/limiting functions necessary to pre-process audio, wideband-data and SAT cellular communications systems using the AMPS/NAMPS or TACS/ETACS/JTACS specifications.

Selectable inputs available to the transmit path are: a choice of two microphones and DTMF/signaling, with access, in this path, to external compression circuitry. Operationally the TX path provides input gain/filtering, a deviation limiter and MX826 TX Modulation Drive controls. In the RX path the SAT signal is separated from the incoming audio via a filter block and made available at a separate pin for mixing externally with the TX Modulation Drive.

The MX826 RX path consists of an input gain/filter block for voice, inputs from an external audio expansion system and an output gain control driving either a loudspeaker system or earpiece.

Unique to the MX816/MX826/836 cellular audio processors is the ability to route audio (TX or RX) to an external Voice Store and Retrieve (VSR) device such as the MX802 or MX812 thus providing the radio system with a voice answering and announcement facility using external DRAM.

As a member of the DBS800 family, the MX826 follows C-BUS protocol. (C-BUS is the serial interface used by all DBS800 integrated circuits.) The MX826, a low-power CMOS device which reduces the amount of microcircuits and components required in a cellular audio system by providing more functions on a single chip, is available in 28-pin SOIC and CDIP packages.