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Software for Telecoms & Audio
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R2 MF Transmitter DSP C Code
Description:
generates dual-tone signals to ITU Q.441 R2 signalling format. R2 transmission
is done by choosing tone-pair combinations from the following two 6-tone
groups:
| Forward direction | Backward direction |
| 1380/1500/1620/1740/1860/1980Hz | 1140/1020/ 900/ 780/ 660/ 540Hz |
The
composite tone signal can send one of 15 digits (6C2 = 15) in each direction
according to the digit code set.
The C code is suitable for any processor with
an ANSI-compliant C compiler. It is designed especially for efficient
operation on low-cost fixed-point DSP- and general-purpose micro-processors.
All data memory is specified as 16-bit integer words. Multiplies are integer
16x16-bit with 32-bit products.
The software is in the form of three callable
subroutines: one sets common-channel default parameters, one initialises
per-channel memory, and one is for per-sample tone-pair generation from
the digit supplied at routine entry. The transmit power is made user-programmable.
The software can be operated in
a multi-channel mode: a pointer is set to each per-channel block of memory
at each sub-routine call. By making multiple sub-routine calls, the code
can also generate blocks of samples. Sample
rates of 8.0kHz or 9.6kHz can be operated. A user's guide is supplied.
Specification:
| Transmit power: | TP where TP <= 0dBm (+6dBm is total peak power) |
| Tone accuracy: | 0.06Hz error |
The value PT is user-programmable.
Processor Load:
| MIPS# | Data memory (words) | Prog memory (bytes)# |
| 0.81 | 1(common)+7(/channel) | 0.24k |
-
#example figures from compiling for the TI TMS320C5000(C55x) DSP processor
at 8.0kHz sampling
Availability: NOW - sale is under licence - integration support offered
