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DTMF Transmitter DSP C Code

Description: generates digit signals to standard Dual Tone Multi-Frequency (DTMF) telephone format. With DTMF, the 16 possible digits are each signified by pairs of tones, one from a "low" group - 697Hz, 770Hz, 852Hz, 941Hz - and the other from a "high" group - 1209Hz, 1336Hz, 1477Hz, 1633Hz.
         The user is responsible for supplying the codes of digits to be dialled and for accepting each transmit sample. Digits can be stored in a queue. The software is in the form of four callable subroutines: one sets common-channel default parameters, one initialises per-channel memory, one is for loading each new digit into each digit queue, and one is for per-sample generation.
         To suit applications, the following parameters are made user-programmable: low- and high-tone transmit powers, digit-on timing, digit-off timing, digit queue length. For test purposes, continuous transmission can be set. Sample rates of 8.0kHz or 9.6kHz can be operated.

Specification: the values PL, PH and Ton, Toff are user-programmable.

Per-tone power: PL & PH where PL,PH -3dBm (+6dBm is total peak power)
Tone accuracy: 0.06Hz error
Digit on-timing: Ton \ with granularity in sample-rate periods - max. is 3.5secs.
Digit off-timing: Toff /

Processor Load:

MIPS# Data memory (words) Prog memory (bytes)#
0.6 4(common) + 12*(per channel) 0.5k

- - #example figures from compiling for the TI TMS320C5000(C55x) DSP processor at 8.0kHz sampling
- *for 16-digit queue

Availability: NOW, sale is under licence - integration support offered

 
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