ISD-T360SB Datasheet, PDF (51/109 Pages) List of Unclassifed Manufacturers – VoiceDSP Digital Speech Processor with Master/Slave, Full-Duplex Speakerphone, Multiple Flash and ARAM/DRAM Support

2—SOFTWARE
ISD-T360SB
PCM RECORDING
The VoiceDSP is capable of recording data in
PCM format (that is the original samples format
either in 8 bits u-Law format, 8 bit A-law format or
16 bits linear format). The PCM data uses more
storage space, but it provides the highest quality
for OGM, music-on-hold or IVS data. The PCM re-
cording may be selected as one of the available
compression rates during the R command
(compression_rate = 0).
Silence Compression and variable Speed Play-
back are not feasible during PCM recording and
playback since this feature skips the compres-
sion algorithm.
2.3.2 DTMF DETECTION
The VoiceDSP processor detects DTMF, which
enables remote control operations. Detection is
active throughout the operation of the VoiceD-
SP processor. Detection can be configured using
the SDET (Set Detectors Mask) command, which
controls the reporting of the occurrence of
tones, and the RDET (Reset Detectors) com-
mand which resets the detectors. The accuracy
of the tone length, as reported by the tone de-
tectors, is ±10 ms.
DTMF detection may be reported at the starting
point, ending point, or both. The report is made
through the status word (for further details, see
GSW command).
For further details about tunable parameters re-
fer to table 2-6 of the Command description sec-
tion.
The DTMF detector performance, as measured
on the line input using an ISD-DS360-DAA board,
is summarized below (see Table 2-1).
Detection Sensitivity
Accepted DTMF Length³
Frequency Tolerance
S/N Ratio
Minimum Spacing⁴
Normal Twist
Reverse Twist⁵
Table 2-1: DTMF Detector Performance¹
Play/IVS Synthesis
Performance depends on the message being
played.²
>50 ms
±1.5%
12 dB
>50 ms
8 dB
4 dB or 8 dB
Record/Idle
−34 dBm
>40 ms
±1.5%
12 dB
>45 ms
8 dB
4 dB or 8 dB
1. Performance depends on the DAA design. For reliable DTMF detection:
- A hardware echo-canceler, that attenuates the echo by at least 6 dBm, is required during playback.
- The HW AGC, if present, must be disabled during playback.
2. Performance with echo canceler is 10 dB better than without echo canceler. For a silent message, Detection
sensitivity is −34 dBm, with echo canceler.
3. Tune parameters 60 and 61 may improve DTMF detection sensitivity. for more details refer to the parameters
description in Table 2-6.
4. The accuracy of reported DTMF tones is ±10 ms.
5. If the interval between two consecutive identical DTMF tones is less than, or equal to, 20 ms, the two are detected
as one long DTMF tone. If the interval between two consecutive identical DTMF tones is between 20 ms and 45 ms,
separate detection is unpredictable.
6. Determined by the DTMF_REV_TWIST tunable parameter value.
ISD
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