AlgoTron DSP
Software for Telecoms & Audio |
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Caller ID Generator (Japan) TMS320C5000 DSP CodeDescription:
implements Caller IDentity - CID - generation for communicating call data
on-hook over telephone lines to subscribers as implemented in Japan. Here
before the 1st normal ring, the exchange sends a line reversal followed
by a set of short rings that should be inaudible in a normal subscriber
phone. The phone responds by going off-hook, triggering the exchange to
send the CID message data. After reception, the phone reverts to on-hook,
and the exchange continues with normal ringing. CID Encoder - sequences the pre-amble of mark carrier signal for a user-set period, followed by the fixed start 5 bytes, then bytes from the message data buffer adding parity, then the fixed end 2 bytes, and finally the formed CRC byte-pair The Encoder generates line signal samples using the following routine, available on its own: CID Transmitter (as used with "standard" CID) - accepts pre-amble or message data bytes adding start/stop bits then, with per-sample timing for 1200b/s, frequency-modulates at V.23 (1300Hz Mark, 2100Hz Space) to generate each transmit sample The Generator requires
a buffer of the complete message data to be pre-loaded at the user interface
in parameterised byte form, excluding the CRC bytes. Message parameterisation
in the user code gives flexibility in dealing with Caller ID categories.
The message buffer format is 2 per 16-bit word for efficiency in multi-channel
use. Processor Load:
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#figures are for TMS320C54x operation with the assembler interface at
8.0kHz sampling Availability: NOW - sale is under licence - integration support offered |
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