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AMBE-3000F™ Vocoder Chip Users Manual
Version 3.4, April, 2014
In
itial Design Considerations
4.5.5 Skew Control (SK_ENABLE TQFP pin 6 BGA pin D3)
The AMBE-3000F™ Vocoder Chip processes speech in voice frames that are approximately 20 ms in duration. Skew control
can provide the designer with flexibility in dealing with clock drift. The AMBE-3000F™ Vocoder Chip skew control feature
allows the vocoder chip to compensate for drift between the frame and sample rate clocks.
Codec Mode
When skew control is enabled, the AMBE-3000F™ Vocoder Chip adjusts the frame boundaries so that they occur on the rising
edge of the TX_RQST signal. The user must generate the TX_RQST signal such that the frame size varies between 156 and
164 samples.
Packet Mode Skew Control Enable
In packet mode the normal length of the input speech packets is 160 samples. However this can vary between 156 and 164
samples in length. Output speech packets can also vary in length from 156 to 164 samples.
4.5.6 Noise Suppressor (NS_ENABLE TQFP pin 7 BGA pin D2)
The integrated Noise suppressor feature of the AMBE-3000F™ Vocoder Chip is used to reduce the effect of background noise
in the encoder input signal. The Noise suppressor is applied to both silence frames and voice frames, but not tone frames.
When the noise suppressor is started it may take up to a few seconds to converge allowing for it to begin fully working.
4.5.7 Companding Using A-Law and µ-Law
The format of the digital speech I/O is critical to designing a system with superior voice quality. It is recommended that, when
possible, 16-bit linear PCM data sampled at 8 kHz, be used for maximum voice quality. The AMBE-3000F™ Vocoder Chip
supports either 16-bit linear, 8-bit A-law, or 8-bit µ-law formats. Given that a-law and law companding formats already
incorporate some compression to reduce the number of bits per sample, when choosing either format, pay particular attention to
Signal to Noise ratios and Frequency Responses of any filters that may be present on the analog front end. The a-law and
law interfaces are provided for the design engineer who is trying to fit to pre-existing conditions or is under other cost type
restraints. To enable/disable companding and select the format, use either hardware pins as described in the following tables or
the COMPAND field (ID 0x32) as part of a Control packet.
CP_ENABLE TQFP pin 8 BGA pin D1
Companding Disabled 0
Companding Enabled 1
Table 11 Companding Control
CP_SELECT TQFP pin 9 BGA pin F5
Select µ-law 0
Select a-law 1
Table 12 Companding Selection
(Subject to Change) Page 34
DVSI CONFIDENTIAL PROPRIETARY
- AMBE-3000F™ Vocoder Chip 1
- DVSI Confidential Proprietary 1
- (Subject to Change) Page v 5
- (Subject to Change) Page x 10
- 1 Product Introduction 11
- 1.3 Typical Applications 12
- 2 Hardware Information 13
- 2.2 Package Details 14
- (Subject to Change) Page 5 15
- 2.3 Pin Assignment Layouts 16
- A B C D E F G H J K L M N P 17
- (Subject to Change) Page 8 18
- (Subject to Change) Page 9 19
- 2.5 Pin Out Table 20
- PARITY_ENABLE 79 22
- Input Enable parity bit 22
- Table 1 Pinout List 26
- 2.7.1 External Clock Source 29
- 2.7.2 Crystal Oscillator 29
- Table 7 Voltage Supply Pins 32
- 3.6 Reset Behavior 33
- Figure 11 TX_RDY after Reset 34
- Figure 12 Output Levels 34
- 3.8 Power-Down Sequencing: 35
- 3.9 Low Power Modes 35
- 3.9.1 Run State 36
- 3.9.2 Idle State 36
- 3.9.3 Standby State 36
- 3.9.4 Halt State 36
- 3.9.5 Power Modes 37
- 4.2 Interface Selection 40
- 4.4 Vocoder State 41
- Figure 18 Typical Echo Path 43
- Table 11 Companding Control 44
- 5 I/O Management 45
- Table 13 ECMODE_IN Flags 46
- Table 14 ECMODE_OUT FLAGS 46
- Table 15 DCMODE_IN Flags 47
- Table 16 DCMODE_OUT Flags 47
- 5.2 Codec mode 49
- “0 to Transition”“1” 51
- “Packet_ _Zone”Uncertainty 51
- “aperiodic packets” 52
- 5.3 Packet Mode 53
- Figure 29 Packet Mode 55
- 5.5 SPI Interface 56
- 5.6 UART Interface 57
- 5.7 McBSP Interface 58
- 5.8 Parallel Interface 61
- Table 26 PPT Timing 62
- Figure 36 Vocoder Front End 64
- Diagram 66
- 6.1 Overview 68
- 6.2 Codec Mode Operation 68
- 6.3 Packet Mode Operation 68
- 6.4 Packet Interfaces 69
- 6.5 Packet Format 69
- 6.5.3 TYPE (1 byte) 70
- 6.5.4 Packet Fields 70
- Table 59 PKT_CODECSTOP Field 78
- Table 61 PKT_CHANFMT Field 79
- samples dcmode 80
- Table 64 PKT_SPCHFMT Field 80
- 0x54 0x46 0x00 81
- Table 71 PKT_READY Field 82
- Table 72 PKT_HALT Field 82
- Table 73 PKT_RESET Field 82
- 6.7.1 Speech Packet Fields 89
- Table 100 CMODE Field Format 90
- Table 103 TONE Field Format 90
- 6.11 Example Packets 94
- 7 Appendices 98
- Table 115 Rate Index Numbers 100
- 8 Support 103
- Digital Voice Systems, Inc 104
- 10 IC Chip Software Errata 107
- Release 007 09/10/2009 108
- Release 014 08/31/2012 108
- 11 History of Revisions 109
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