Telecommunications Applications With the TMS320C5x DSPs Application Book 1994 Digital Signal Processing Products Printed in U.S.A., October 1994 SPRA033 Application Telecommunications Applications Book With the TMS320C5x DSPs 1994 Telecommunications Applications With the TMS320C5x DSPs Edited by Mansoor A. Chishtie Digital Signal Processing Applications — Semiconductor Group Texas Instruments Incorporated SPRA033 October 1994 Printed on Recycled Paper Part I Introduction Part II Digital Cellular Systems Part III Speech Synthesis Part IV Error-Correction Coding Part V Baseband Modulation and Demodulation Part VI Equalization and Channel Estimation Part VII Speech and Character Recognition Algorithms Part VIII System Design Considerations Part IX Bibliography IMPORTANT NOTICE Texas Instruments (TI) reserves the right to make changes to its products or to discontinue any semiconductor product or service without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing orders, that the information being relied on is current. TI warrants performance of its semiconductor products and related software to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. Certain applications using semiconductor products may involve potential risks of death, personal injury, or severe property or environmental damage (“Critical Applications”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED, OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT APPLICATIONS, DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. Inclusion of TI products in such applications is understood to be fully at the risk of the customer. Use of TI products in such applications requires the written approval of an appropriate TI officer. Questions concerning potential risk applications should be directed to TI through a local SC sales office. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards should be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or services described herein. Nor does TI warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. Copyright 1994, Texas Instruments Incorporated Preface This book belongs to a growing series of digital signal processing application books that Texas Instruments has published over the years. Some of these books are broad in content and cover a wide variety of DSP-related technologies and applications. Others are more focused and concentrate on one DSP application area. TI has also published many individual application reports. This particular collection of application reports focuses primarily on a variety of DSP applications that are related to the field of telecommunications and implemented on the ’C5x generation of the TMS320 family. This book is divided into nine parts, including the introduction and the bibliography: Part I Introduction Part II Digital Cellular Systems Part III Speech Synthesis Part IV Error-Correction Coding Part V Baseband Modulation and Demodulation Part VI Equalization and Channel Estimation Part VII Speech and Character Recognition Algorithms Part VIII System Design Considerations Part IX Bibliography Part I introduces the TMS320 family and the TMS320C5x generation; it also summarizes various telecommunications applications that use TMS320C5x DSPs. Parts II – VIII discuss major application topics. Most of the papers presented here are application reports written either by the engineering staff of the TI digital signal processing department (including factory and field personnel and summer students) or by third parties. Some of the papers were contributed by other departments within TI. It is generally assumed that reader is DSP literate and has some exposure to the TMS320 DSP family. The application reports presented in this book represent practical implementations of DSP algorithms. Source code associated with these reports is not listed in this book because of space constraints. However, most of the papers have associated source code that is publicly available from the TMS320 DSP Bulletin Board System (BBS) at 713–274–2323. The contents of this BBS are also mirrored at an Internet anonymous FTP site ti.com. Some technical papers included here present commercial implementations that are licensable from respective organizations. The technical data sheets of these implementations will also be included in a future update of the TMS320 Software Cooperative Library. The editor would like to thank all the contributors and reviewers of this book. In particular, a special note of appreciation goes to Gene Frantz, Jay Reimer, Raj Chirayil, and Paul Buenaflor for their encouragement and helpful suggestions in improving the overall structure of this book. It is our hope that this book will help you in making the transition to DSP-based telecommunication applications. Lastly, the editor would like to acknowledge the untiring efforts of Ms. Katie Delbridge in planning and coordinating this project. Mansoor A. Chishtie Telecom Applications Digital Signal Processing Semiconductor Group Texas Instruments Incorporated iii iv Contents Title Page Part I: Introduction Introduction . 1 Overview . 3 Programmable Versus Hard-Wired Solutions. 3 Fixed-Point Versus Floating-Point Solutions. 4 TMS320 Digital Signal Processors. 5 TMS320C5x Architecture. 7 Summary of Telecom Applications Topics. 9 Bibliographies and Other References. 10 Part II: Digital Cellular Systems Digital Cellular Phone: A Functional Analysis. 11 Introduction . 13 Transmitter . 14 Receiver . 24 Summary . 29 References . 29 IS-54 Simulation . 31 Introduction . 33 Description . 35 Using the Simulation. 39 Code Availability. 40 References . 40 Part III: Speech Synthesis Theory and Implementation of the Digital Cellular Standard Voice Coder: VSELP on the TMS320C5x. 41 Introduction . 43 Overview of VSELP. 43 Speech Decoder. 57 Features of VSELP. 59 TMS320C5x Real-Time Implementation. 59 A Typical Digital Cellular Vocoder Configuration. 60 Code Availability. 61 References . 61 v Contents Title Page Part IV: Error-Correction Coding U.S. Digital Cellular Error-Correction Coding Algorithm Implementation on the TMS320C5x. 63 Abstract . 65 Introduction . 65 VSELP Channel Format. 66 FACCH Channel Format. 73 Code Availability. 75 References . 75 Viterbi Implementation on the TMS320C5x for V.32 Modems. 77 Introduction . 79 Standard V.32 Encoder. 82 Viterbi Decoder. 85 Viterbi Decoder Implementation. 90 Performance Analysis. 96 Summary . 100 Code Availability. 100 References . ..