The digital
voice processor compresses the analog voice signal using the proprietary
CELP algorithm, encodes the data, and transmits it to the air using
the conventional analog radio. The GFSK modulation with four levels
is used in the wireless link. On the receiving side, the processor demodulates
the signal and decompresses it back to voiceband. The link operates
in the single frequency time division duplex mode (TDD) that eliminates
needs for the duplex filter for the two-way communication.
Most of the conventional analog radios can be used for this type of
link with the minimal modifications.
The processor was built using ADSP-2185 DSP.
