AMBE2000 ETC, AMBE2000 Datasheet - Page 30

• Manufacturer Part Number: AMBE2000
• Description: VOCODER CHIP
• Manufacturer: ETC

5.3.1 Formatted Output : Word 0 : Header
The header is a 16 bit word that begins each valid frame corresponding to 20 milliseconds of speech. This field will always be
0x13EC.
5.3.2 Formatted Output : Word 1 : ID (Power Control)
The encoder will always use 0x00 in the 8-bit field of an output frame.
5.3.3 Formatted Output : Word 1 :Control Word 1
This 8-bit control word indicates the activity of various functions.
Decoder Frame Repeat: When the Decoder Frame Repeat flag is set to 1, the decoder is reporting that the last frame decoded
was a repeat of the previous frame.
Decoder Silence Detect: When the Decoder Silence Detect flag is set to 1, the decoder is reporting that the last frame decoded
was a comfort noise frame.
Encoder DTMF Detect: The Encoder DTMF Detected Flag will be set to a 1 when the encoder detects a DTMF tone. The
DTMF Detect option is controlled by the DTMF Detect/Generate bits in control Word 10 described in section 5.2.8 enable the
DTMF Detect option.
Silence Detect: The Encoder Silence Detected Flag will be set to 1 when no voice activity is detected. The Silence Detect
option is controlled by and can be disabled by the VAD as described in section 5.2.9.
5.3.4 Formatted Output : Words 2-6 : Rate Info 0, Rate Info 1, Rate Info 2, Rate Info 3,
Words 2-6 in the packet indicate the rate at which the AMBE-2000™ encoder is operating . These words are output. See
tables 5-C and 5-D for corresponding values.
5.3.5 Formatted Output: Word 7 : Bit Error Rate
This status field is used for the decoder to report bit error information. The 16 bit number output is used to compute the BER
using the following calculation
5.3.6 Formatted Output : Word 10 : DTMF Control
This word corresponds to the DTMF Detection capabilities of the vocoder. It uniquely identifies specific tones recognized by
the encoder. See table 5-J for a list of tones and their corresponding values.
Rate Info 4.
Unused
7: MSB
Table 5-J Control Word 1 Format
Unused
% BER = (Word 7) / (32768)
6
Decoder
Repeat
Frame
Confidential Proprietary, Subject to Change
Control Word 1 – 8-bits (See Table 1-A)
5
User’s Manual Version 3.0
Decoder
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Silence
Detect
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Unused
3
Unused
2
Encoder
Silence
Detect
1
Encoder
0 : LSB
Detect
DTMF