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Digital Voice Systems AMBE-2020 User Manual

Vocoder chip
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Digital Voice Systems, Inc.
The Speech Compression Specialists
AMBE-2020™ Vocoder Chip
User's Manual
Version 4.92 June, 08

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Summary of Contents for Digital Voice Systems AMBE-2020

  • Page 1 Digital Voice Systems, Inc. The Speech Compression Specialists AMBE-2020™ Vocoder Chip User’s Manual Version 4.92 June, 08...
  • Page 2 Digital Voice Systems, Inc. shall not be liable for any errors or for incidental or consequential damages in connection with the furnishing, performance, or use of this manual or the examples herein. This includes business interruption and/or other loss which may arise from the use of this product.
  • Page 3 1. Preliminary Statements and Definitions 1.1 This nonexclusive end user product license agreement is a legal agreement between the customer (the END USER) and Digital Voice Systems, Inc. (DVSI) covering the terms and conditions under which DVSI's proprietary content (that may consist of and is not limited to software, hardware, documentation and other material) is licensed to the END USER as part of this PRODUCT.
  • Page 4 DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 limited to, all sales, use, rental receipt, personal property or other taxes which may be levied or assessed in connection with this Agreement.

  • Page 5: Table Of Contents

    Product Introduction General Information Advantages Typical Applications AMBE-2020™ Application Design Overview Basic Operation Initial Design Considerations 2.2.1 A/D – D/A Overview 2.2.2 Vocoder Front End Requirements 2.2.3 Channel Interface Overview 2.2.4 Speech and FEC Rate Selection Overview Hardware Information Special Handling Instructions 3.1.1...
  • Page 6 Interfacing to the Texas Instruments PCM3500 Codec Expanded Tone Detection and Generation Soft Decision Decoding Special Rate 2350 bps Voice / 50 bps FEC AMBE-1000™ Vocoder Chip Compatible Mode 62 DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™...

  • Page 7: Product Introduction

    Typically for higher error rate channels, the user will apportion a greater percentage of the total bit rate to FEC coding. The AMBE-2020™ voice coder maintains natural voice quality and speech intelligibility at rates as low as 2.0 kbits/sec. The ...

  • Page 8: Typical Applications

    1.3 Typical Applications Satellite Communications Digital Mobile Radio Secure Communications Cellular Telephony and PCS Voice Multiplexing Voice Mail Multimedia Applications DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 Page 8...

  • Page 9: A/D – D/A Overview

    Basic Operation In its simplest model, the AMBE-2020™ can be viewed as two separate components, the Encoder and the Decoder. The Encoder receives an 8kHz sampled stream of speech data (16-bit linear, 8-bit Alaw, or 8-bit ulaw) and outputs a stream of channel data at the desired rate.

  • Page 10: Vocoder Front End Requirements

    -1 dB -2 dB -18 dB -35 dB -40 dB 0 200 DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 Vocoder Front End Analog Digital A-to-D Input Input Convertor...

  • Page 11: Channel Interface Overview

    20ms of speech data input into the encoder). This structure also embeds some status type flags, meant for local control DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 3000 3400 4000 4600 Figure 2 - D.

  • Page 12: Speech And Fec Rate Selection Overview

    Chip to run in Passive or Active modes. In Passive mode, data strobes are provided by an external source, while in Active mode, data strobes are provided by the AMBE-2020™ Vocoder Chip. Serial interfaces can be run in Passive or Active modes.

  • Page 13: Special Handling Instructions

    The 100 pin TQFP package design of the AMBE-2020™ Vocoder Chip allows it to be mounted by infrared reflow, vapor- phase reflow or equivalent processes. The peak package body temperature must not exceed 220 C.

  • Page 14: Pin Descriptions

    Input should be unconnected. Input AMBE-2020™ Reset pin. Active LOW. See Section 3.3 Encode Packet Ready: Following a reset, this signal will have a high to low transition to Output indicate the first packet is ready. The next packet will be ready approximately 20 msec later.
  • Page 15 66,78,91,92, 93,94,95,96, 97,98,99, NOTE 1: The AMBE-2020™ expects an encoder packet to be read approximately every 20 msec. Following the initial reset, wait for EPR to go low and read the initial packet (t following packets use the procedure below: 1) Wait for slightly less than 20 msec.

  • Page 16: Clock And Reset Timing

    Clock and Reset Timing To reset the AMBE-2020™ chip, the reset signal must be held low for a minimum of 50 µs. The recovery time from reset is approximately 95 msec. In other words, 95 msec after the rising edge of the reset signal the AMBE-2020™ starts processing PCM samples.

  • Page 17: Associated Chip Delay

    1ms of idle time between encode and decode sequence. DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 (INT) Parameter 11.5 ms (encoder) + 1 ms* + 7.5 ms = 20 ms...

  • Page 18: Crystal / Oscillator Usage

    Crystal / Oscillator Usage The AMBE-2020™ 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: Keep the crystal and external capacitors as close to the X2/CLKIN and X1 pins as possible to minimize board stray capacitance.

  • Page 19: Package Description

    100 pin TQFP (Thin Quad Flat Pack) All Dimensions are in millimeters DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 Figure 3-F Package Dimensions 16.20 / 15.80 SQ 14.20 / 13.80 SQ 12.00 TYP...
  • Page 20 AMBE-2020-10 = The DVSI device part number. DVSI = Digital Voice Systems, Incorporated D16877PZ-66 = Internal Texas Instruments part number for the AMBE-2020 = WF Code = Die Rev Code = Die Shrink Code 43AT3FW = Lot Trace Code = 2 Digit YR/MO Code (Updated Monthly)

  • Page 21: Electrical Characteristics And Requirements

    Low-level input voltage High-level output current Low-level output current DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 Normal Operating Conditions Operating Voltage Operating Case Temperature Range Storage Temperature Range...

  • Page 22: Thermal Resistance Characteristics

    Thermal Resistance Characteristics ΘJA ΘJC Table 3G Thermal Resistance Characteristics DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 Test Conditions = 3.3 ±V, I = MAX = MAX = MAX, V...

  • Page 23: Channel Interface

    (usually at start-up). These control functions include speech data and FEC rate control. It is important to realize that not all data being output from the AMBE-2020™ is intended for transmission over the channel. Status type of data is typically only useful at the ‘local’ end. In most voice transmission systems, the actual encoded bits are extracted from the channel formatting, combined into the systems transmission stream, sent over the transmission path, extracted from the transmission path at the receiving end, and reassembled into the AMBE-2020™...

  • Page 24: Serial Configuration Selection

    1 to 4 voice data bits carried within each word. These four configurations can be seen in Table 4-B. See section 4.3 for all the details on the serial interface. DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 Interface Select Pins Port Type...

  • Page 25: Channel Serial Mode

    The signals in Table 4-C make up the serial channel interface. The serial channel mode transfers data in and out of the AMBE-2020™ using 16 bit words on the two data lines CHAN_RX_DATA and CHAN_TX_DATA. The selection of the framed or unframed format of this data is made using information in Table 4-A.

  • Page 26: Low Level Timing For Passive And Active Serial Mode

    Hold time, FSR after CLKR falling edge h(FSR) Hold time, DR after CLKR falling edge h(DR) DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 c(SCK) w(SCK) w(SCK) su(DR) h(DR)
  • Page 27 Note: H = 7.629 ns; however, do not operate serial clocks any faster than 2.048 MHz. Thus t 488.3 nsec. DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 3.3 Volts Units 2H-5...

  • Page 28: Channel Data Format

    9600bps, the coded voice bits are filled starting from the MSB of the first word in the field, leaving any unused bits as zeros. It is important to note here that even when the AMBE-2020™is operating at less than 9600bps, all 384 bits of the Framed format (including any unused trailing zeros) must be transferred out of the encoder and into the decoder.

  • Page 29: Framed Input: Word 1 : Power Control Id

    Set the 8-bit Power Control ID field to 0x00 for normal use. For Power Down Mode, set this value to 0x55. This causes the AMBE-2020™ to enter low power mode. To exit low power mode, the device must be reset through the hardware.

  • Page 30: Framed Input: Words 2-6 : Rate Information

    Indicator Lost Frame Indicator : Setting the Lost Frame Indicator bit to a 1 will cause the AMBE-2020™ decoder to construct the voice frame using the parameters from the previous frame. This is an effective way to mask the effects of short periods of data loss.

  • Page 31: Framed Input: Word 7 : Unused In Input

    0xbf9b 0x0080 0x0000 0xab5d 0x3400 0x0000 0xbfc0 0x0000 0x0000 0xab16 0xe400 0x0000 Table 5-D Rate Selection Using Rate Info 0-4, AMBE-2020™ only (AMBE+) Rate Info 0 Rate Info 1 Rate Info 2 0x0028 0x0000 0x0000 0x5048 0x0000 0x0000 0x1030 0x0001...

  • Page 32: Framed Input: Word 11 : Control Word 2

    Decoder output volume control The default gain value is set to 0x80h DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 DTMF Control – 16-bits DTMF Digit Frequency 1 (Hz)

  • Page 33: Framed Input: Words 12-23 : Channel Data

    As is noted in the Channel Interface definitions, these unused bits must still be clocked out of the AMBE-2020™. The packet must always consist of 24 word Framed Output Format The format for framed output data is shown in Figure 5-B.

  • Page 34: Framed Output: Word 1 : Power Control Id

    Encoder DTMF Detect: The Encoder DTMF Detected Flag will be set to a 1 when the encoder detects a DTMF tone. DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 Figure 5-B Basic Framed Output Format Description...

  • Page 35: Framed Output: Word 8 : Soft Decision Distance

    Rate Info 0, Rate Info 1, Rate Info 2, Rate Info 3, Rate Info 4. Words 2-6 in the packet indicate the rate at which the AMBE-2020™ encoder is operating . These words are output. See tables 5-C and 5-D for corresponding values.
  • Page 36 DTMF Amplitude DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 Description An input signal shall not be rejected as a DTMF tone if its amplitude is greater than -25 dBm0 (maximum sinusoid dBm0 is defined as+3.17 dBm0).

  • Page 37: Framed Output: Word 11: Control Word 2

    This field is used to indicate which part of the device is affected by words 2-6, the rate control words. DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 DTMF Digit Frequency 1...

  • Page 38: Framed Output: Words 12-23 : Channel Data

    As is noted in the Channel Interface definitions, these unused bits must still be clocked out of the AMBE-2020™. The packet must always consist of 24 words.

  • Page 39: Unframed Serial Input Format

    2 bits per Word Format 3 bits per Word Format 4 bits per Word Format DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 Data Control Offset Control Data Page 39...

  • Page 40: Configuring The A/D-D/A Interface Using Codec_Sel[1-0]

    A/D-D/A Overview The interface from the analog world of speech to the AMBE-2020™ is typically an A/D-D/A chip. Selection of the A/D- D/A chip should be made carefully, with a preference given to 16 bit linear devices. Additionally, consideration should be given for signal to noise ratios and filtering characteristics typically built into many such devices.

  • Page 41: Low Level A/D–D/A Timing

    Hold time, FSR after CLKR falling edge h(FSR) Hold time, DR after CLKR falling edge h(DR) DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 c(SCK) w(SCK) h(FSR) w(SCK) su(FSR)
  • Page 42 Note: H = 7.629 ns; however, do not operate serial clocks any faster than 2.048 MHz. Thus t minimum of 488.3 nsec. DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 3.3 Volts Units 2H-5...

  • Page 43: Hardware Vs. Software Selection Note

    Coding Rate Selection The Voice coding rate as well as the FEC coding rate can be selected individually on the AMBE-2020™. These rates are selected by using 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.

  • Page 44: Voice Activity Detection (Vad), Comfort Noise Insertion (Cni)

    Table 7-B Rate Selection Using Rate Info 0-4, AMBE-2020™ only (AMBE+™)* RATE_SEL4 RATE_SEL3 RATE_SEL2 *Note: AMBE+ is only used for speech rates at 3600 bps and higher. Any rates below 3600 bps use a modified algorithm similar to the AMBE algorithm.

  • Page 45: Dual Tone Multiple Frequency, Detection And Generation

    Normal Power and Power Saving Modes Power savings can be achieved during times of longer inactivity of the AMBE-2020™ chip by placing it into one of three available Low Power Modes. The chip can be placed into low-power and stand-by modes via hardware or software Control Words.

  • Page 46: Slip Enable

    In any real time communication system, clock skew issues must be anticipated to keep the flow of data smooth from one end of the system to the other. The SLIP_EN (pin 82) signal allows the encoder of the AMBE-2020™ to react to small slips in the encoder channel signals.
  • Page 47 This is the simplest method of slip control and is the default method provided slip control is enabled (SLIP_EN is high) on the chip. In this method the vocoder chip’s internal slip adjustment of 160 to 161 sample per frame is used. In order to work properly, the system designer must set-up the sample rate and packet timing so that the following constraint is met: 160 <...
  • Page 48 The preferred method for using Slip Control Packets is to monitor the availability of data from the AMBE-2020™ vocoder chip and to only input Slip Control Packets into the data stream sent to the AMBE-2020™ as needed. Note that for this method slip control must be enabled (SLIP_EN is high) on the chip.

  • Page 49: Example: Ad73311 Usage

    CODEC_TX_DATA AMBE-2020™ REFERENCE DATA The AMBE-2020™ sends the following configuration sequence to the AD73311 when CODEC_SEL[1-0]=01b: 0x8113, // write 13 to CRB of AD73311, MCD=1 (DMCLK=MCLK/2),SCD=0(SCLK=DMCLK/8) 0x82f9, // write f9 to CRC of AD73311, 5VEN, REFOUT, all Power ON 0x8300, // write 0 to CRD of AD73311...

  • Page 50: Example: Texas Instruments Tlv320Aic10 Usage

    Example: Texas Instruments TLV320AIC10 Usage The Texas Instruments’ TLV320AIC10 codec presents a simple low cost solution for use with DVSI’s AMBE-2020™ vocoder chip. This application note provides information on interfacing these components. Figure 1 shows a sample block diagram interface, between the TLV320AIC10 codec and DVSI’s AMBE-2020™ vocoder chip.
  • Page 51 The control registers in the TLV320AIC10 codec must be initialized for proper operation. The recommended procedure is to initialize the TLV320AIC10 by writing data to its 4 control registers through the DCSI port, while the AMBE-2020™ is held in reset. The timing for the DCSI port is shown in Figure 2.
  • Page 52 CNTL_DATA [15:0] AIC_LOAD SCLK Figure 3: TLV320AIC10 Codec Configuration Detail DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 SHIFT D_IN [15:0] Serial Out LOAD LS_IN CLK_EN COUNT AIC_CTRL AIC_LOAD...
  • Page 53 AMBE-2000™ Vocoder Chip Users Manual TLV320AIC10 Reference Schematic (Analog Section) 820pF 3.3VA 10uF Handset Reference Materials: AMBE2020™ Vocoder chips Users Manual: http://www.dvsinc.com/literature.htm TLV320AIC10 Data Sheet: http://www-s.ti.com/sc/ds/tlv320aic10.pdf TLV320AIC10 EVM User’s Guide: http://www-s.ti.com/sc/psheets/slwu003d/slwu003d.pdf Application Report – Understanding Data Converters: http://www-s.ti.com/sc/psheets/slaa013/slaa013.pdf DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com...

  • Page 54: Configuring The Ad73311 For 3-Volt Operation

    Figure 2: The AMBE-2020™ with the AD73311 Configured for 3-volt operation. The objective of this circuit is to tri-state the output of the AMBE-2020™ CODEC_TX_DATA. This allows the DSP or Microcontroller to communicate with the AD73311 to send it the desired configuration.
  • Page 55 The Analog Devices AD73311L is a low power 3 volt version of the AD73311. It is possible to use this part with the AMBE-2000™ or AMBE-2020™ vocoder chip utilizing the method described above for sending alternate configuration words to the AD73311 CODEC. Table 3 lists alternate control words for configuring the AD73311L for use with the AMBE-2000™...

  • Page 56: Interfacing To The Texas Instruments Pcm3500 Codec

    Interfacing to the Texas Instruments PCM3500 Codec The Texas Instruments PCM3500 codec chip presents a simple low cost solution for use with DVSI’s AMBE-2000™ or AMBE-2020™ vocoder chips. This application note provides information on alternative methods of interfacing these components.
  • Page 57 It is strongly recommended that the user review the Application Information provided in the Texas Instruments PCM3500 data sheet before finalizing any design. Additional Reference Material AMBE-2000™ or AMBE-2020™ vocoder chip Users Manual http://www.dvsinc.com/literature.htm Application Report – Understanding Data Converters: http://www-s.ti.com/sc/psheets/slaa013/slaa013.pdf...
  • Page 58 47nF 3.3VA 10uF Handset 0.2uF 3.3VA 5.6K 4.7K 10uF 2.1K 100nF Analog In 3.3 V 220K CODEC_TX/RX_CLK CODEC_TX/RX_STRB CODEC_TX_DATA 3.3VA CODEC_RX_DATA 3.3VA 10uF Figure 2 2.2uF 3.3 V Vcom 4.7uF Vref1 AGND Analog Out Vref2 Vout 4.7uF AGND 3.3 V AGND /PDWN Loop...

  • Page 59: Expanded Tone Detection And Generation

    Expanded Tone Detection and Generation The AMBE-2000™ is capable of detecting and generating single tones as well as dual tones. The single tones span from 156.25 Hz to 3812.5 Hz in 31.25 Hz steps. Tone Index (Decimal) ……… 123-127 …………. 147-254 Freq #2 Tone Type...

  • Page 60: Soft Decision Decoding

    Decision Value Placing a logic high on pin 79 of either the AMBE-2000™ or AMBE-2020™ vocoder chips enables the soft decision error correction on the decoder. Enabling the soft-decision does nothing to the encoder packet. The packet will look like a normal encoded packet.
  • Page 61 Word # DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com AMBE-2000™ Vocoder Chip Users Manual Version 4.92, June, 08 Table 1. Soft-Decision Decoder Packet Description Header always set to 0x13EC Power Control (8 bits) Rate info 0 Rate info 1...

  • Page 62: Special Rate 2350 Bps Voice / 50 Bps Fec Ambe-1000™ Vocoder Chip Compatible Mode

    Pin 73 Table 1. Compatible Mode Procedure Step 1. To enable the AMBE-2000/2020™ to interoperate with the AMBE-1000™ Vocoder Chip at the rate of 2350 bps voice + 50 bps FEC, first send the packet described in Table 2. Word #...
  • Page 63 Compatible Mode Procedure Step 3. After the packets detailed in Table 2 and Table 3 are sent into the AMBE-2000/2020™ Vocoder Chip the RIS bits in Control Word 2 must be set to 0x3 for each subsequent packet. If the rate is changed or the device is reset, the above procedure (steps 1, 2 and 3) must be repeated.

  • Page 64: History Of Revisions

    Serial Configuration Selection Channel Serial Interface Pin Descriptions Table 6-A CODEC_SEL[1-0]: A/D- D/A Hardware Configuration Values Added AD73311 to AMBE-2020™ connection diagram Pin Description : ENCODER_EN is pin 24. Corrections of Table 4A and 4B Clarification on VAD Expanded description of Control Word 1...
  • Page 65 May 07 Sept 07 Feb, 08 4.91 March 08 Revised the AMBE-2020™ Vocoder Chip END USER License Agreement Revised Pin 86 VAD_EN pin Voice Activity Detection description to clearify 4.92 June 08 enable/disable and ON/OFF Control. DVSI Confidential Proprietary, Subject to Change Visit us at www.dvsinc.com...

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