AMBE-2000™ Vocoder Chip

User’s Manual Version 3.0

page 29

Confidential Proprietary, Subject to Change

Echo Canceller (EC) :

Set this bit to 1 to enable the echo cancel function on a frame by frame basis. This must be set to 1 in every packet sent to

continue use.

Sleep (SL) :

Set this bit to 1 to enter Sleep mode on a frame by frame basis. Sleep is a low power mode, not to be confused with Power

Down Mode. The sleep function must be enabled in every packet to continue in sleep mode. Set this bit to 0 to exit Sleep

mode.

VAD :

In order to set the Voice Activity Detector on, set the VAD bit to 1. To disable Voice Activity Detection, set the VAD bit to 0.

5.2.10 Formatted Input : Words 12-23 : Channel Data

This is the field that contains the actual coded bits. Input of the data begins with the MSB of the first word in this field and

continues through with the final bit output being the LSB of the final word. If the data rate selected is less than 9600bps then

the unused bits in each frame are zero and populate the end of the field. As is noted in the Channel Interface definitions, these

unused bits must still be clocked out of the AMBE-2000™. The packet must always consist of 24 words.

5.3

Formatted Output Format

The format for Formatted output data is shown in Figure 5-B. It is only the bits in the Voice Data Bits field, which are

transmitted along with framing information (data used to locate the start of each frame for proper reconstruction at the decoder)

over the channel. The first 192 bits provide overhead information, which is sometimes useful to the host but is generally not

transmitted over the channel.

Figure 5-B Basic Formatted Output Format

Word #

Description

0

Header always set to 0x13ec

1

Power Control (8bits)

Control Word 1 (8 bits) – see Table 5-J

2

Rate info 0

3

Rate info 1

4

Rate info 2

5

Rate info 3

6

Rate info 4

7

Bit Error Rate

8

Unused

9

Unused

10

DTMF Control – see Table 5-L

11

Control Word 2 – see Table 5-N

12

Channel Data

13

Channel Data

14

Channel Data

15

Channel Data

16

Channel Data

17

Channel Data

18

Channel Data

19

Channel Data

20

Channel Data

21

Channel Data

22

Channel Data

23

Channel Data