Digital Voice Systems VC-20-MR2 User Manual

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Background Noise Condition

VSELP @ 8.0 kbps

Mean Opinion

Score

(

or DMOS)

FIRSTPLAC

DIGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

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Voted To be The BEST…

Best

Vocoder

MOS

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3.8

3.6

3.4

3.2 3

2.8

2.6

2.4

2.2 2

Clean (MOS) Traffic

(DMOS)

Truck Noise

@ 15dB

AMBE Voice Coder @ 3.6 kbs Avg. of Others @ 3.6 bps

Truck Noise

@ 6dB

Babble

(DMOS)

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DIGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

VC-20 AMBE Vocoder Board

USERS MANUAL

Version 2.0

VC-20 AMBE™ Vocoder Board User’s Manual

Page 4

VC-20 AMBE™ Vocoder Board User’s Manual

IGITAL

OICE

YSTEMS

, INC.

The Speech Compression Specialists

VC-20 AMBE™ Vocoder Board User’s Manual

This document may not, in whole or in part be copied, photocopied, reproduced, translated, or reduced to any electronic medium or machine readable form without prior consent in writing from Digital Voice Systems, Incorporated.

Every effort has been made to ensure the accuracy of this manual. However, Digital Voice Systems, Inc. makes no warranties with respect to the documentation and disclaims any implied warranties of merchantability and fitness for a particular purpose. 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. The information in this document is subject to change without notice.

Trademarks

VC-20 AMBE Vocoder Board is registered trademarks of Digital Voice Systems, Inc. Other product names mentioned may be trademarks or registered trademarks of their respective companies and are the sole property of their respective manufacturers.

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The Speech Compression Specialists

IGITAL

OICE

YSTEMS

, INC.

VC-20 AMBE™ Vocoder Board END USER License Agreement

1.0 Preliminary Statements and Definitions

1.1 "Voice Codec" shall mean the hardware, software and associated documentation referred to in the invoice or shipping papers accompanying this agreement for which END USER has requested a license, and any derivative works thereof, including modifications, enhancements and extensions made by or for Digital Voice Systems, Inc. (DVSI) and including circuit diagrams, timing diagrams, programmable logic software, logic diagrams, layouts, operating instructions and user manuals.

1.2 "AMBE™ Software" shall mean the speech coding software and/or firmware provided as part of the Voice Codec. This software is contained in the Read Only Memories (ROMS, EPROMS, EEPROMS, etc...) which are included as part of the Voice Codec. This software includes any derivative works which have as their source the software contained in the Read Only Memories, and it includes the software contained in any future Read Only Memories which DVSI may provide END USER for use in the Voice Codec.

1.3 "Designated Site" shall mean the location of the Voice Codec.

1.4 "Proprietary Information" shall mean the information which DVSI desires to protect against unrestricted disclosure or competitive use and which is designated as such in writing by DVSI or is disclosed orally and within thirty (30) days thereafter is reduced to tangible form pursuant to this License.

1.5 DVSI represents that it owns certain “Proprietary Rights” in the Technology and the AMBE Voice Compression Software, including patent rights in the Technology, and patent rights, copyrights, and trade secrets in the AMBE Voice Compression Software.

2.0 License Granted

2.1 Subject to the conditions herein and upon initial use of the AMBE™ Software within the VC-20 AMBE™ Vocoder Codec , DVSI hereby grants to END USER a non-exclusive, limited license to use the AMBE® Voice Compression Software in machine readable form solely on the AMBE-1000™ Vocoder Chip. Title to the AMBE® Voice Compression Software remains with DVSI. No license is granted for use of the AMBE® Voice Compression Software on other than the Voice Codec. No license, right or interest in any trademark, trade name or service mark of DVSI is granted under this Agreement.

2.2 END USER shall not copy, extract, de-compile, reverse engineer or disassemble the AMBE® Voice Compression Software contained in the VC-20 AMBE™ Vocoder Board.

2.3 Transfer of License

(a) END USER may transfer the AMBE™ Software and all rights under this agreement to a third party together with a copy of this Agreement provided that END USER provides DVSI with a written notification of the transfer and provided that the third party agrees in writing to accept all the terms and conditions of this agreement. Upon any such transfer, END USER's rights under this Agreement shall terminate pursuant to Section 3.0.

(b) END USER may relocate the Voice Codec, and the subsequent location shall then be considered the Designated Site.

License and Warranty

(c) Except as provided in this Section 2.2, this Agreement, the AMBE™ Software and any other information provided by DVSI to END USER and any licenses and rights granted hereunder, may not be sold, leased, assigned, sublicensed or otherwise transferred, in whole or in part, by END USER.

2.4 END USER shall not de-compile, reverse engineer or disassemble the AMBE™ Software.

3.0 Term and Termination

3.1 This Agreement is effective upon initial use of the AMBE™ Software on the Voice Codec and shall remain in effect until terminated in accordance with this agreement.

3.2 This Agreement shall terminate automatically without notice from DVSI if END USER fails to comply with any of the material terms and conditions herein. END USER may terminate this Agreement at any time upon written notice to DVSI certifying that END USER has complied with the provisions of Section 3.3.

3.3 Upon termination of this Agreement for any reason, END USER shall: (i) have no further rights to the AMBE™ Software; (ii) discontinue all use of the AMBE™ Software; and (iii) destroy or, at DVSI's option, return all copies of the AMBE™ Software.

4.0 Payments

4.1 In consideration of the hardware, software, and associated materials provided as part of the Voice Codec, and in consideration of the license and rights in the AMBE™ Software granted by DVSI, and in consideration of DVSI's performance of its obligations hereunder, END USER agrees to pay to DVSI the fee specified in DVSI's invoice.

4.2 In consideration of the materials provided as part of the Voice Codec, and in consideration of the license and rights in the AMBE Voice Compression Software granted by DVSI, and in consideration of DVSI's performance of its obligations hereunder, END USER agrees to pay to DVSI the fee specified in DVSI's invoice.

5.0 Proprietary Notices

5.1 END USER shall not remove any copyright or proprietary notice on the on the AMBE Voice Compression Software or VC-20 AMBE™ Vocoder Board.

6.0 Proprietary Information

6.1 The parties agree that the AMBE Voice Compression Software shall be considered Proprietary Information.

6.2 Except as otherwise provided in this Agreement, END USER shall not use, disclose, make, or have made any copies of the Proprietary Information, in whole or in part, without the prior written consent of DVSI.

6.3 END USER shall make reasonable efforts to notify and inform its employees having access to the Proprietary Information of END

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License and Warranty

USER's limitations, duties and obligations regarding nondisclosure and copying of the AMBE™ Software. Proprietary Information shall be used only by employees of END USER and only at the Designated Site, except as provided under this agreement.

6.4 END USER shall have no obligations for disclosure or use of Proprietary Information which: (i) is already known to END USER, at time of disclosure by DVSI; (ii) is or becomes publicly known through publication, inspection of product or otherwise through no wrongful act of END USER; (iii) is received from a third party without restriction and without breach of this Agreement; (iv) is independently developed by END USER; (v) is disclosed to a third party by or on behalf of DVSI without restriction; or (vi) is approved for release or use by written authorization of DVSI.

6.5 Notwithstanding any termination pursuant to Section 3.0, the obligations set forth in this Section 6.0 shall survive termination of this Agreement.

7.0 Limited Warranty

7.1 DVSI warrants the Voice Codec and the AMBE™ Software to be free from defects in materials and workmanship under normal use for a period of ninety (90) days from the date of delivery. DVSI further warrants that the Voice Codec and the AMBE™ Software operate in accordance with the written specifications delivered to END USER with the Voice Codec.

7.2 Except as stated in Section 7.1, the Voice Codec and AMBE™ Software are provided "as is" without warranty of any kind. DVSI does not warrant, guarantee or make any representations regarding the use, or the results of the use, of the Voice Codec or AMBE™ Software with respect to its correctness, accuracy, reliability, currentness or otherwise. The entire risk as to the results and performance of the Voice Codec or AMBE™ Software is assumed by the END USER. After expiration of the warranty period, END USER, and not DVSI or its employees, assumes the entire cost of any servicing, repair or correction of the Voice Codec or the AMBE™ Software.

7.3 DVSI warrants that it has the right to enter into this Agreement and to grant a license to use the AMBE™ Software to END USER.

7.4 Except as specifically set forth in this Section 7.0, DVSI makes no express or implied warranties including, without limitation, the warranties of merchantability or fitness for a particular purpose or arising from a course of dealing, usage or trade practice, with respect to the Voice Codec or AMBE™ Software. Some states do not allow the exclusion of implied warranties, so the above exclusion may not apply to END USER. No oral or written information or advice given by DVSI or its employees shall create a warranty or in any way increase the scope of this warranty, and END USER may not rely on any such information or advice. The limited warranties under this section 7.0 give END USER specific legal rights, and END USER may have other rights which vary from state to state.

8.0 Limitation of Liability

8.1 In no event shall DVSI be liable for any special, incidental, indirect or consequential damages resulting from the use or performance of the Voice Codec or VC-20 AMBE™ Vocoder Board whether based on an action in contract, tort (including negligence) or otherwise (including, without limitation, damages for loss of business profits, business interruption, and loss of business information), even if DVSI or any DVSI representative has been advised of the possibility of such damages.

8.2 Because some states do not allow the exclusion or limitation of liability for consequential or incidental damages, the above limitations may not apply to END USER.

8.3 DVSI's maximum liability for damages arising under this Agreement shall be limited to 20% (twenty percent) of the fees paid by END USER for the particular Voice Codec or VC-20 AMBE™ Vocoder Board which caused the damages or that is the subject matter of, or is directly related to, the cause of action.

9.0 Taxes

9.1 All payments required under Section 4.0 or otherwise under this Agreement are exclusive of taxes and END USER agrees to bear and be responsible for the payment of all such taxes (except for taxes based upon DVSI's income) including, but not limited to, all sales, use, rental receipt, personal property or other taxes which may be levied or assessed in connection with this Agreement.

10.0 Export

10.1 United States export laws and regulations prohibit the exportation of certain products or technical data received from DVSI under this Agreement to certain countries except under a special validated license. As of May 20, 1996 the restricted countries are: Libya, Cuba, North Korea, Iraq, Serbia, Montenegro, and Iran. The END USER hereby gives its assurance to DVSI that it will not knowingly, unless prior authorization is obtained from the appropriate U.S. export authority, export or re-export, directly or indirectly to any of the restricted countries any products or technical data received from DVSI under this Agreement in violation of said United States Export Laws and Regulations. DVSI neither represents that a license is not required nor that, if required, it will be issued by the U.S. Department of Commerce. Licensee shall assume complete and sole responsibility for obtaining any licenses required for export purposes.

11.0 Governing Law

11.1 This Agreement is made under and shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts, except that body of law governing conflicts of law. If any provision of this Agreement shall be held unenforceable by a court of competent jurisdiction, that provision shall be enforced to the maximum extent permissible, and the remaining provisions of this Agreement shall remain in full force and effect.

12.0 Notices

12.1 Any notices to DVSI which may be given hereunder shall be in writing and sent to: Digital Voice Systems Inc., 234 Littleton Road, Westford, MA., 01886, U.S.A.

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Contents

IGITAL

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, INC.

The Speech Compression Specialists

TABLE OF CONTENTS

Section 11 PRODUCT INTRODUCTION ..................................................................1

1.1 GENERAL INFORMATION..........................................................................1

1.2 VC-20 AMBE™ VOCODER BOARD FEATURES: .......................................2

1.3 AMBE-1000™ VOCODER CHIP FEATURES: ............................................2

1.4 AMBE™ VOCODER APPLICATIONS:........................................................2

Section 22 VC-20 AMBE™ VOCODER BOARD OVERVIEW...................................5

2.1 ADVANCED MULTI-BAND EXCITATION (AMBE

2.2 VC-20 AMBE VOCODER BOARD BASIC OPERATION ............................. 5

2.3 SPECIAL HANDLING AND STORAGE PRECAUTIONS ....................................7

Section 33 BOARD SET-UP & CONFIGURATION ....................................................9

3.1 CONNECTION SPECIFICATIONS................................................................9

3.2 DIN41612 96-PIN CONNECTOR SPECIFICATIONS...................................10

3.3 VC-20-MR2 CONNECTOR SIGNALS ......................................................11

3.4 VC-20-MR2 CONNECTOR SIGNALS ......................................................11

3.5 VC-20-MR2 ON-BOARD JUMPERS CONNECTOR SIGNALS........................15

3.6 VC-20-MR2 DTMF TONE DATA...........................................................15



VOCODER)........................5

Section 44 DVSI SERVICES AND SUPPORT SOLUTIONS......................................17

4.1 TECHNICAL SUPPORT...........................................................................17

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Section 1- Product Introduction

1 Product Introduction

1.1 General Information

The Digital Voice Systems, Inc. (DVSI) VC-20-MR2 voice codec is a full-duplex

real-time voice processing board. The VC-20-MR2 contains proprietary software which implements the Advanced Multi-Band Excitation (AMBE™) voice coding algorithm. DVSI grants a license to its customers to use this software according to the terms established in the attached AMBE™ Software END USER License Agreement. Use of the VC-20-MR2, or any portion thereof, signifies acceptance of these licensing terms.

The VC-20-MR2 operates by digitizing an analog speech signal using an on-board

A-to-D converter. This digitized speech is then processed by the encoder and converted into a 4.8/2.4 kbps data bit stream. This bit stream is output to a modem or similar device. Simultaneously, the VC-20-MR2 receives a 4.8/2.4 kbps data bit stream from a modem or similar device. This received bit stream is processed by the decoder and converted into a synthetic speech signal which is then converted into an analog signal using the on-board D-to-A converter. The encoder and decoder are fully asynchronous.

The VC-20-MR2 (4800bps) has been designed to be robust to both acoustic

background noise and channel errors. It generally contains sufficient channel error protection to produce high quality speech at bit error rates up to 1-2% and intelligible speech at bit error rates up to 4-5%.

The VC-20-MR2 (2400bps) has been designed to be robust to acoustic background

noise and limited channel errors. The VC-20-MR2 (2400) will produce intelligible speech at bit error rates up to 1-2%.

The VC-20-MR2 includes a number of advanced features such as an

automatic Voice/Silence detection (VAD), adaptive comfort noise generation, DTMF detection and signaling, soft-decision decoding, frame stealing support and echo cancellation. Operation of these features is described in the following sections. The VC-20-MR2 is also capable of supporting optional features such as external codecs and downloading

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Section 1 – Product Introduction

custom software.

It provides a real-time, full-duplex implementation of the standard-setting AMBE voice compression technology. This technology patented by DVSI has been proven to outperform CELP and other competitive technologies. Numerous evaluations have shown its ability to provide performance equal to today’s digital cellular systems at under half the data rate. The AMBE voice compression algorithm is used in applications throughout the world, including the next generation of digital mobile communication systems.

1.2 VC-20 AMBE™ Vocoder Board Features:

IGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

• High Quality Low Data Rate Speech Coding

• Extremely Flexible Bit Rate Selection

1.3 AMBE-1000™ Vocoder Chip Features:

• High Quality Low Data Rate Speech Coding

• DVSI Full Duplex AMBE Voice Coder

• Supports Data Rates of 2.4 kbps and 4.8 kbps

• Self-Test Loop-Back Mode

• Echo Cancellation

• Dual Tone / DTMF

• Power-Down Mode

1.4 AMBE™ Vocoder Applications:

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The Speech Compression Specialists

Section 1- Product Introduction

• Cellular Telephony and PCS

• Satellite Communications

• Digital Mobile Radio

• Secure Communications

• Voice Multiplexing

• Voice Mail

• Multimedia Applications

• Video Conferencing

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Section 2 – VC-20 AMBE™ Vocoder Board Overview

2 VC-20 AMBE™ Vocoder Board Overview

2.1 Advanced Multi-Band Excitation (AMBE Vocoder)

2.2 VC-20 AMBE Vocoder Board Basic Operation

The Advanced Multi-Band Excitation (AMBE Vocoder) technology is based on the Multi-Band Excitation (MBE) speech model. This speech model provides a unique speech coding framework which results in a number of advantages over linear prediction based speech coders such as CELP, RELP, VSELP, MELP, ECELP, MP-MLQ, and LPC-10, etc. .

(1)

The AMBE voice coder (vocoder) was first developed in the mid 1990’s by Digital Voice Systems, Incorporated. This vocoder maintains speech intelligibility and naturalness at rates as low as 2.4 kbits/sec. The AMBE Vocoder system is less complex than either CELP or VSELP, and therefore, it is easily integrated into low-cost, low-power, communication integrated circuits.

Connections are made to the VC-20-MR2 using the attached DIN 41612 connector

which is described in Sections 4 and 5. The user must supply the VC-20-MR2 with a 5v digital power supply and a +/-5v analog power supply. It is preferable to decouple the analog supply from the digital supply by using separate power supplies.

The VC-20-MR2 contains one set of jumpers which is used to loop-back the encoder

signals to the decoder, and to enable the on-board clocks and frame signals. The pin assignment for this jumper is documented in Section 6.

The VC-20-MR2 can be operated in loop-back mode by using the internal clock and

frame generator to generate the clock signals, TXCK and RXCK, and the frame signals, FMEN and FMDE, as shown in Figure 2. Jumpers 1-12 on the fourteen pin jumper block should be connected and all other jumpers should be disconnected.

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Section 2 - VC-20 AMBE™ Vocoder Board Overview

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The Speech Compression Specialists

The VC-20-MR2 can be connected to a modem or similar device as shown in Figure

3. The modem or the VC-20-MR2 can generate the clocks (TXCK and RXCK) and frame synchronization (FMEN and FMDE). The modem reads the data from the encoder on the data line TXD. Simultaneously the decoder reads data from the modem on data lines RXD, RXD1, RXD0, HD_SD, DESLNCE and LOST.

Note: if soft-decision information is available the HD_SD signal should be held low,

otherwise the HD_SD signal should be held high so that only the MSB (RXD) of the data signal will be read by the decoder.

The frame signals FMEN and FMDE are used to signify the beginning of each data

frame for the encoder and decoder, respectively. The required timing relationship between these signals is shown in Figure 5. In order to operate in this mode, jumpers 5-10 and 12-14 should be disconnected. If the VC-20-MR2 is generating the clocks and frames, then jumpers 1-4 should be connected, otherwise, they should be disconnected. Jumper 11 is disconnected if the LOST signal is used, otherwise it is connected.

A final operating mode allows two VC-20-MR2's to be connected together using

their on-board clocks to generate the signals TXCK, FMEN, RXCK and FMDE. In this mode the encoder on the first VC-20-MR2 is connected to the decoder on the second VC-20-MR2. Similarly, the decoder on the first VC-20-MR2 is connected to the encoder on the second VC-20-MR2. This is shown in Figure 4.

Generally, the encoder signals on each board are synchronized with the oscillator on

that board, and the decoder signals on each board are synchronized with the oscillator on the other board. This is done by connecting jumpers 1, 3 and 11 on each board. All other jumpers should be disconnected. The HD_SD control signal must be held high or left unconnected to disengage soft-decision decoding. Care must be taken that only one clock generator is connected to each of the clock signals TXCK, FMEN, RXCK and FMDE.

The ECHO signal should be held low to enable the onboard echo cancellor. The 5

ms echo cancellor included in the VC-20-MR2 is generally sufficient for canceling electrical echo introduced by a near hybrid (4-to-2 wire converter). If the ECHO signal is held high or left disconnected the echo cancellor is disabled.

The VAD signal should be held low to enable the onboard Voice/Silence detection

and Adaptive Comfort Noise features. When enabled the ENSLNCE signal is switched to indicate the presence of Voice. If the VAD signal is held high or left disconnected, both Voice/Silence detection and Adaptive Comfort Noise are disabled, and the ENSLNCE signal always indicates voice.

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Section 2 – VC-20 AMBE™ Vocoder Board Overview

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The Speech Compression Specialists

Note that for proper operation any background noise present in the speech must be

short term stationary and have a level less than -25 dBm0.

The RATE signal controls which version the VC-20-MR2 voice codec runs.

Holding the RATE high selects the 4.8kbs. system , holding it low selects the 2.4kps. system.

2.3 Special Handling and Storage Precautions

CAUTION

Handling Instructions

Although the VC-20 AMBE™ Vocoder Board incorporates input protection

circuitry, to avoid damage from the accumulation of a static charge, industry standard electrostatic discharge precautions and procedures must be employed during handling and installing.

Storage

To insure maximum shelf life in long term storage, VC-20 AMBE™ Vocoder

Board should be kept in a moisture controlled package at <40°C and <90% RH.

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The Speech Compression Specialists

Section 6 – Advanced Features

3 Board Set-up & Configuration

3.1 Connection Specifications

Connector:

Type DIN 41612 Connector (male)

Physical:

Description 100 mm (Single Euro-card [3U]) height (see Figure 6)

Analog Input:

Type single-ended

Impedance 600 ohm

Sensitivity 0 dBm0 = 0 dBm Sinusoidal

Overload

Nominal Level -23 dBm0 (average speech level)

Dynamic Range +/- 10 dB (relative to Nominal Level)

Noise Level -72 dBm0

Analog Output:

Type single-ended

Impedance low impedance output, capable of driving a 600 ohm load

Sensitivity 0 dBm0 = 0 dBm Sinusoidal

Overload

Nominal Level -23 dBm0 (average speech level)

Dynamic Range +/- 10 dB (relative to Nominal Level)

Noise Level -72 dBm0

Bandwidth 20 – 3700 Hz.

Digital Interface:

Type TTL compatible

Power:

+3.17 dBm0

2 watts @ 5v digital, .2 watts @ +/- 5v analog

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Section 6 – Advanced Features

3.2 DIN41612 96-pin Connector Specifications

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The Speech Compression Specialists

ROW C ROW B ROW A

Pin Function Name Function Function Name

1 Dig. Pwr. VCC Rsvd. Dig. Pwr. VCC 2 Dig. Pwr. VCC Rsvd. Dig. Pwr. VCC 3 Gnd. GND Rsvd. Gnd. GND 4 Output TXD Rsvd. Rsvd. 5 Rsvd. Rsvd. Input TXCK 6 Input FMEN Rsvd. Output RUN 7 Rsvd. Rsvd. Output RESX 8 Gnd. GND Rsvd. Gnd. GND

9 Input RXD Rsvd. Rsvd. 10 Rsvd. Rsvd. Input RXCK 11 Input FMDE Rsvd. Input HD_SD 12 Rsvd. Rsvd. Rsvd. 13 Gnd. GND Rsvd. Gnd. GND 14 Rsvd. Rsvd. Rsvd. 15 Output DTMF_DET Rsvd. Input DINRS 16 Output DTMF_DAT Rsvd. Rsvd. 17 Output ENSLNCE Rsvd. Rsvd. 18 Input RXD1 Rsvd. Rsvd. 19 Input RXD0 Rsvd. Rsvd. RATE 20 Gnd. GND Rsvd. Gnd. GND 21 Input LOST Rsvd. Rsvd. 22 Rsvd. Rsvd. Input FS 23 Rsvd. Rsvd. Input ECHO 24 Input VAD Rsvd. Rsvd. 25 Input DESLNCE Rsvd. Rsvd. 26 Gnd. GND Rsvd. Gnd. GND 27 Anlg Pwr. +5v analog Rsvd. Anlg Pwr. +5v analog 28 Anlg Pwr. -5v analog Rsvd. Anlg Pwr. -5v analog 29 Output VFRO Rsvd. Input VFXI 30 Anlg Gnd AGND Rsvd. Anlg Gnd AGND 31 Gnd. GND Rsvd. Gnd. GND 32 Gnd. GND Rsvd. Gnd. GND

Note: Pwr. - Pwr.OWER I - INPwr.UT to the VC-20-MR2 O - OUTPwr.UT from the VC-20-MR2 R - RESERVED (Leave Unconnected)

Note: Many Reserved signals are used to monitor the internal state of the VC-20-MR2. To ensure proper operation all reserved signals must be left unconnected.

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Section 6 – Advanced Features

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The Speech Compression Specialists

3.3 VC-20-MR2 Connector Signals

Name Dir Description

+5v Pwr. Analog +5v +/- 10%

-5v Pwr. Analog -5v +/- 10% DESLNCE I Decoder silence control (Active Low) DINRS I Reset Signal (Active High) DTMF_DAT O DTMF Tone Data DTMF_DET O DTMF Tone Detected Flag (Active High) ECHO I Echo Cancellor Enable (Active Low) ENSLNCE O Encoder Silence Detected (Active Low) FMDE I Decoder frame flag (Active High) FMEN I Encoder frame flag (Active High) FS I Frame Steal Flag (Active Low) GND Pwr. Digital Ground GND Anlg Pwr. Analog Ground HD_SD I Enable Soft-decision Decoding (Active Low) LOST I Lost speech frame detected flag (Active High) RATE I Rate selection pin. (High : 4.8bps., Low : 2.4bps.) RESX O Internal Reset Status (Active Low) RUN O Run Status Signal (Active High) RXCK I Receive data bit clock (4.8/2.4 kHz) RXD I Receive data I channel (MSB) RXD0 I Receive data I channel (LSB) RXD1 I Receive data I channel TXCK I Transmit data bit clock (4.8/2.4 kHz) TXD O Transmit data I channel VAD I Voice/Silence Detection Enable (Active Low) VCC Pwr. Digital +5v +/- 5% VFRO O Analog speech output signal VRXI I Analog speech input signal

3.4 VC-20-MR2 Connector Signals

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Section 6 – Advanced Features

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DESLNCE

DINRS

DTMF_DAT

DTMF_DET

ECHO

ENSLNCE

The DESLNCE flag signals the decoder that silence has been detected during the current frame. If DESLNCE is held low, the decoder ignores the current frame of channel data and outputs comfort noise on VFRO. This signal is sampled on the falling edge of the first clock cycle of each 20 ms decoder frame. Note that if DESLNCE is connected to ENSLNCE either directly or through a voice activated channel, then adaptive comfort noise generation is enable whenever DESLNCE is low.

DINRS is a VC-20-MR2 reset signal. An active high level on DINRS for a duration of at least 300 ns will reset the VC-20-MR2. DINRS will generate RESX and RESET. The VC-20-MR2 will pull this signal to its inactive state (low) when it is not being driven by an external source (it may be left unconnected if not being used).

If the VC-20 detects a dtmf tone, it outputs four bits of data identifying the tone on the DTMF_DAT signal (see Section 7). The data is output during the four clock cycles when DTMF_DET is high. The data is synchronous with the rising edge of TXCK. This signal should be ignored when DTMF_DET is inactive.

The DTMF_DET flag is activated by the encoder if it detects a dtmf tone on VRXI. The DTMF_DET is brought high on a rising edge of TXCK and held high for four clock cycles. During this time the DTMF data is output on DTMF_DAT. The DTMF_DET flag is only output once for each continuous dtmf tone that is detected. DTMF_DET can only be active during the first four clock cycles of a 20 ms data frame.

The ECHO signal must be held low to enable the onboard 5 ms echo cancellor. This signal is sampled on the falling edge of the first clock cycle of each 20 ms encoder frame. If left unconnected, this signal is pulled internally to the disabled state (high).

The ENSLNCE signal indicated whether the encoder has detected voice or silence during the current frame. A high value (inactive) indicates voice was detected while an active low value indicates silence (or background noise) was detected. The ENSLNCE signal changes state at the beginning of each channel output frame as indicated by FMEN. This signal can be connected to DESLNCE to enable adaptive comfort noise generation. The ENSLNCE flag is deactivated by the encoder 40 ms. prior to the onset of voice activity as shown in Figure 1.

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IGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

Section 6 – Advanced Features

FMDE

FMEN

GND, AGND

HD_SD

RATE

LOST

Voice

Silence

Voice

Silence

Voice

FMEN

ENSLNCE

Figure 1: Voice/Silence Detection Timing

This is the decoder frame flag which identifies the beginning of the channel input frame. FMDE must be held high for one clock period of RXCK every 96 clock cycles (20 ms).

This is the encoder frame flag which identifies the beginning of the channel output frame. FMEN must be held high for one clock period of TXCK every 96 clock cycles (20 ms).

The FS signal can be held low to signal the encoder that the next 20 ms frame will be stolen, i.e. replace with inband data. This allow the encoder to compensate for the missing frame in subsequent frames, thereby improving overall quality. This signal is sampled on the falling edge of the first clock cycle of each 20 ms encoder frame. If low, the encoder assumes the next frame will be stolen and outputs a special frame steal packet on TXD. If left unconnected, this signal is pulled internally to the disabled state (high).

GND is the digital ground signal and AGND is the analog ground signal. These signals are connected on the VC-20-MR2.

The HD_SD signal must be set low to enable soft-decision decoding or held high to disable soft decision decoding. This signal is sampled on the falling edge of the first clock cycle of each 20 ms decoder frame. If left unconnected, this signal is pulled internally to its inactive state (high).

The LOST flag is active if the current frame of channel data is invalid, in which case the decoder ignores the current frame of channel data and performs a frame repeat. This signal is sampled on the falling edge of the first clock cycle of each 20 ms decoder frame.

The RATE signal controls the data rate of the voice codec. The two available rates are 4800 bps. and 2400bps. Holding this signal HIGH runs the 4800bps. system and holding it LOW runs the 2400bps. system. This signal is sampled on the falling edge of the first clock cycle of each 20 ms encoder frame.

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Section 6 – Advanced Features

IGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

RESX

RUN

RXCK

RXD, RXD1,

RXD0

TXCK

TXD

VAD

VFRO

RESX is the reset status output signal. It is active when the VC-20-MR2 is being reset. The VC-20-MR2 is reset under three conditions: during power-up, as a result of DINRS being asserted, or as a result of a Watch-Dog Timer reset. This signal is an active low output. RESX is the VC-20-MR2's actual hard-reset signal; whereas, RESET is a software flag that is synchronous with TXCK.

RUN is a status signal that signifies that the VC-20-MR2 is encoding and decoding speech. This signal drives the green LED. Each data frame is divided into an encoder window and a decoder window. The RUN signal is active within each respective window when the VC-20-MR2 is encoding or decoding speech (see Figure 6). RUN is synchronous with TXCK.

This is the decoder symbol clock which controls the transfer of the channel data into the decoder. This signal must be 4.8/2.4 kHz +/- .05%. RXD, RXD1, RXD0, FMDE, LOST, and DESLNCE must be synchronous with the rising edge of this clock signal to within 500 ns and held stable for 100 ns after the falling edge of this clock signal.

RXD, RXD1, and RXD0 are the data signals input to the decoder. These signals provide three bits of soft-decision information, with RXD being the MSB and RXD0 being the LSB. These signals are each clocked into the VC-20-MR2 on each falling edge of RXCK resulting in a total data rate of 4.8/2.4 kbps. Note that when interfacing to a modem or other device that only provides a single bit of received data (i.e. hard-decision) then this signal should only be connected to RXD and the HD_SD pin should be held high.

This is the encoder data clock which controls the transfer of the channel data out of the encoder. This signal must be 4.8/2.4 kHz +/- .05%. TXD, FMEN, FMEN, RESET, STATUS, and RUN must be synchronous with the rising edge of this clock signal to within 500 ns and held stable for 100 ns after the falling edge of this clock signal.

TXD is the voice data signal from the VC-20-MR2 encoder. This signals changes state on each rising edge of TXCK, giving a total data rate of 4.8/2.4 kbps.

The VAD signal must be held low to enable the onboard Voice/Silence detection and comfort noise generation. This signal is sampled on the falling edge of the first clock cycle of each 20 ms encoder frame. If left unconnected, this signal is pulled internally to the disabled state (high).

VFRO is the analog speech output produced by passing the decoder output through a 16 bit linear codec. VFRO has an analog bandwidth of 100 Hz. - 3700 Hz., and it is constrained to be within +/- 1.5 volts.

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VC-20 AMBE™ Vocoder Board User’s Manual

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IGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

VFXI is the analog speech input which is filtered with a 100 Hz. - 3700 Hz.

VRXI

bandpass filter and then input to the encoder via a 16 bit linear codec. In order to avoid clipping VRXI must not exceed +/- 1.5 volts.

3.5 VC-20-MR2 on-board jumpers Connector Signals

Jumper Signal

1 2 3 4 5 6 7 8 reserved (leave unconnected)

9 reserved (leave unconnected) 10 reserved (leave unconnected) 11 12 13 reserved (leave unconnected) 14

Connects on-board 4.8/2.4 kHz data clock to TXCK Connects on-board 4.8/2.4 kHz data clock to RXCK Connects on-board 20 ms frame clock to FMEN Connects on-board 20 ms frame clock to FMDE Connects TXD to RXD0 (LSB) Connects TXD to RXD1 Connects TXD to RXD (MSB)

Deactivates LOST signal Connects ENSLNCE to DESLNCE signal

reserved (leave unconnected)

3.6 VC-20-MR2 DTMF Tone Data

Section 6 – Advanced Features

The VC-20-MR2 supports dtmf detection, transmission, and generation. The

encoder detects and transmits dtmf tones, and the decoder decodes and generates dtmf tones, in support of standard telephony requirements

In addition, if the VC-20 encoder detects a dtmf tone it activates the DTMF_DET

signal for four clock cycles of TXCK and simultaneously outputs (LSB first) four bits of data on DTMF_DAT which identify the dtmf tone which was detected. The DTMF_DET flag is only output once for each continuous dtmf tone that is detected. The correspondence between the data bits and dtmf tone is shown in Table 1.

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Section 6 – Advanced Features

IGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

DTMF_DAT

MSB…LSB

Keypad

Character

Frequency

0000 1 1209 Hz. 697 Hz. 0001 4 1209 Hz. 770 Hz. 0010 7 1209 Hz. 852 Hz. 0011 * 1209 Hz. 941 Hz. 0100 2 1336 Hz. 697 Hz. 0101 5 1336 Hz. 770 Hz. 0110 8 1336 Hz. 852 Hz. 0111 0 1336 Hz. 941 Hz. 1000 3 1477 Hz. 697 Hz. 1001 6 1477 Hz. 770 Hz. 1010 9 1477 Hz. 852 Hz. 1011 # 1477 Hz. 941 Hz. 1100 A 1633 Hz. 697 Hz. 1101 B 1633 Hz. 770 Hz. 1110 C 1633 Hz. 852 Hz. 1111 D 1633 Hz. 941 Hz.

Table 1: DTMF Tone Data

By default, the VC-20 AMBE is jumpered to use IRQ 11 and I/O ports 0x26c-0x26f.

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VC-20 AMBE™ Vocoder Board User’s Manual

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IGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

Section 7- DVSI Services & Support

4 DVSI Services and Support Solutions

4.1 Technical Support

If you have any problems with the VC-20 AMBE™ or have questions

about its operation, please contact:

Digital Voice Systems, Inc.

234 Littleton Road

Westford, MA 01886 USA

Phone: (978) 392-0002

Fax: (978) 392-880166

email: info@dvsinc.com

web: www.dvsinc.com

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HD_SD, ECHO, VAD, RATE

On-Board Clock & Frame Generator

(jumper 2)

(jumper 1)

(jumper 3)

(jumper 4)

(jumper 12)

(jumpers 5,6,7)

TXCK

FMEN

ENSLNCE

TXD

RXD, RXD1, RXD0

DESLNCE

FMDE

RXCK

LOST

(jumper 11)

ENCODER

DECODER

VFXI

VFRO

Figure 2: Vocoder Connections In Loop-back Mode

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IGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

Section 7- DVSI Services & Support

MODEM

TXCK

FMEN

TXD

ENSLNCE

HD_SD, ECHO, VAD, RATE

RXD, RXD1, RXD0

DESLNCE

FMDE

ENCODER

DECODER

VFXI

VFRO

RXCK

LOST

Figure 3: Typical Connections between Vocoder and a General Modem

Note: Not meant to represent an “off-the-shelf” modem

VC-20 AMBE™ Vocoder Board User’s Manual

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VFRO

VFXI

DECODER

ENCODER

(jumper 1)

(jumper 3)

LOST

(jumper 11)

RXCK

FMDE

DESLNCE

(jumper 12)

RXD

HD_SD, ECHO, VAD, RATE

TXD

ENSLNCE

(jumper 12)

FMEN

TXCK

FMEN

ENSLNCE

TXD

RXD

DESLNCE

FMDE

On-Board

Clock & Frame

Generator

ENCODER

DECODER

VFXI

VFRO

RXCK

LOST

(jumper 11)

On-Board

TXCK

(jumper 1)

Clock & Frame

Generator

(jumper 3)

Figure 4: Dual Vocoder Connections

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RXD, RXD1,

LOST, DESLNCE,

HD_SD, VAD,

20 ms

IGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

Section 7- DVSI Services & Support

TXCK

FMEN

TXD, ENSLNCE

500 ns.

500 ns

1/rate (seconds)

20 ms

1/rate (seconds)

RXCK

FMDE

RXD0

ECHO

Figure 5: Channel Interface Timing Relationships

VC-20 AMBE™ Vocoder Board User’s Manual

N/A

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RUN

20ms

13.25ms

Encoder Window

Figure 6: RUN Signal Timing

6.75ms

Decoder Window

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Figure 7: Vocoder Physical Dimensions

(bottom view)

(side view)

IGITAL VOICE SYSTEMS, INC.

The Speech Compression Specialists

Section 7- DVSI Services & Support

5.5 mm 41612 Connector

< 7.5 mm

3.0 mm

100 mm

112 mm

11 mm

< 7.5 mm

VC-20 AMBE™ Vocoder Board User’s Manual

112 mm

(components < 12.5 mm)

(connections < 2 mm)

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NOTES