AMBE-2000 Digital Voice Systems, Inc., AMBE-2000 Datasheet - Page 40

• Manufacturer Part Number: AMBE-2000
• Description: 2.0 - 9.6 KBPS Single ic For Toll-quality, Low Data Rate, Real Time Speech Compression
• Manufacturer: Digital Voice Systems, Inc.

7
7.1
Many of the functions of the AMBE-2000™ can be accessed through both hardware and software interfaces to the device. The
following hardware inputs, CHANN_SEL [1-0], RATE_SEL [4-0], CODEC_SEL [1-0], VAD_EN, ECHOCAN_EN, and
SLEEP_EN, are only accessed for input during the first 200 microseconds after a hardware reset on RESETN. For predictable
operation these signals must remain stable over this time period. After this initialization period the functions that these pins
access can only be reconfigured through the channel interface described in section 5.2. Changes on these pins after the 200
microseconds initialization period after reset are ignored, unless another reset is performed.
7.2
The Voice coding rate as well as the FEC coding rate can be selected individually on the AMBE-2000™. These rates are
selected by using the Rate Info Words as described in section 5.2.4, or through hardware pins RATE_SEL [4-0] subject to the
restrictions in section 7.1. The five input pins RATE_SEL [4-0] give 32 pre-configured voice/FEC rates. If rates other than
these are desired then the Rate Info Words (in the Framed channel interface) can be used to configure voice and FEC rates in
50 bps increments.
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Special Functions
Hardware vs. Software Selection Note
Coding Rate Selection
Table 7-A Rate Selection Using Rate Info 0-4, compatible w/ AMBE-1000™ (AMBE™)
RATE_SEL4
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Pin
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RATE_SEL3
Pin
0
0
0
1
1
1
0
0
0
1
1
1
1
1
0
0
RATE_SEL2
Pin
0
1
0
0
1
1
0
1
0
0
0
0
1
1
1
1
AMBE-2000™ Vocoder Chip
User’s Manual Version 4.0
RATE_SEL1
Pin
0
0
0
1
1
1
1
1
1
0
1
0
0
0
0
1
RATE_SEL0
Pin
0
1
1
1
1
0
1
1
0
0
0
1
0
1
0
0
Speech Rate
2400
2350
3600
3350
4000
3750
4800
4550
3600
3100
4150
4400
7750
4650
9600
4850
(bps)
FEC Rate (bps)
1200
1700
2250
2800
3350
4750
250
250
250
250
50
0
0
0
0
0
Page 40
Total Rate
2400
3600
4000
4800
6400
7200
8000
9600
(bps)