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Exchange Tone Detector Software for Texas TMS320C54x/C55x DSPs

This software implements an Exchange Tone Detector (ETD) DSP code is for tones such as dial-tone and busy tone that emanate from standard PSTN telephone exchanges. The ETD determines on a sample-by-sample basis whether exchange tone(s) are present or not, leaving the user to monitor for tone cadences if needed eg for busy tone. Because of the variety of tone signals in different countries, a measure of programmability is given to the user. The corner frequencies of the band-pass can be selected from a family of filters.

The code runs on the Texas Instruments TMSC54x/C55x range of 16-bit fixed-point programmable DSP processors. Operation can be set for sample rates of 8.0kHz or 9.6kHz. The software is organised in callable subroutines: a main routine for accepting samples suitable for multiple channels, and an initialisation routine for setting per-channel memory. Each is re-entrant with memory offset-addressing for multi-channel operation.

DSP Load:

• MIPS: 0.64 - 8.0kHz sampling ; 0.77 - 9.6kHz sampling

• Data memory: 22(per channel) words

• Program memory: 159 words

Availability:

NOW - sale is under licence - integration support offered