AMBE-2000 Digital Voice Systems, Inc., AMBE-2000 Datasheet - Page 17

• 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.

3.4
The associated delay due to the coding/decoding algorithm is shown below
Encoder Delay
Algorithmic Delay = 32 ms
Encoder Processing Delay = 11.5 ms
Decoder Delay
Algorithmic Delay = 10 ms
Decoder Processing Delay = 7.5 ms
Total Delay
Frame Processing Delay =
* 1ms of idle time between encode and decode sequence.
3.5
The AMBE-2000™ Vocoder Chip has an input clock frequency of 16.384 MHz. Two options are outlined below in providing
this signal. The CLOCK_MODE pin 51 must be set appropriately for the option used.
The following points should be noted when designing any printed circuit board layout:
3.5.1
If CLOCK_MODE pin is low then a TTL/CMOS source is used as the clock input. Connect X2/CLKIN and X1 as follows:
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Associated Chip Delay
Crystal / Oscillator Usage
TTL Clock Source
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= 32 ms + 11.5 ms + 1 ms* +10 ms +7.5 ms = 62 ms
Figure 3-C X2/CLKIN and X1 with TTL Clock Source
•
•
Keep the crystal and external capacitors as close to the CLK_I and CLK_I2 pins as
possible to minimize board stray capacitance.
Keep X2/CLKIN and X1 away from high frequency digital traces (example CLKOUT)
to avoid coupling.
11.5 ms (encoder) + 1 ms* + 7.5 ms = 20 ms
TTL/CMOS Clock
16.384 MHz
Unconnected
Source
AMBE-2000™ Vocoder Chip
User’s Manual Version 4.0
X2/CLKIN (pin 68)
X1 (pin 67)
AMBE-2000
Page 17