About the Cover PTC uses DSP to narrow the INCLUDING: occupied bandwidth of analog voice signals (p 9). QEX (ISSN: 0886-8093) is published bimonthly in January, March, May, July, September, and November by the American Radio Relay League, A 225 Main Street, Newington CT 06111-1494. Yearly subscription rate to ARRL members is $22; nonmembers $34. Other rates are listed below. Periodicals postage paid at Hartford, CT and at R R additional mailing offices. POSTMASTER: Form 3579 requested. L Send address changes to: QEX, 225 Main St, Newington, CT 06111-1494 Issue No 200 Features David Sumner, K1ZZ Publisher Doug Smith, KF6DX 3 Practical HF Digital Voice Editor By Charles Brain, G4GUO, and Andy Talbot, G4JNT Robert Schetgen, KU7G Managing Editor Lori Weinberg Assistant Editor 9 PTC: Perceptual Transform Coding for Bandwidth Zack Lau, W1VT Contributing Editor Reduction of Speech in the Analog Domain, Pt 1 Production Department By Doug Smith, KF6DX Mark J. Wilson, K1RO Publications Manager Michelle Bloom, WB1ENT Production Supervisor 13 A Low-Cost HF Channel Simulator for Digital Systems Sue Fagan Graphic Design Supervisor By Johan B. Forrer, KC7WW David Pingree, N1NAS Technical Illustrator Joe Shea Production Assistant 23 Notes on Standard Design HF LPDAs, Pt 1: Advertising Information Contact: “Short” Boom Designs John Bee, N1GNV, Advertising Manager 860-594-0207 direct By L. B. Cebik, W4RNL 860-594-0200 ARRL 860-594-0259 fax Circulation Department Debra Jahnke, Manager Kathy Capodicasa, N1GZO, Deputy Manager Cathy Stepina, QEX Circulation 39 The ATR-2000: A Homemade, High-Performance HF Offices Transceiver, Pt 2 225 Main St, Newington, CT 06111-1494 USA By John B. Stephensen, KD6OZH Telephone: 860-594-0200 Telex: 650215-5052 MCI Fax: 860-594-0259 (24 hour direct line) e-mail: [email protected] Subscription rate for 6 issues: Columns In the US: ARRL Member $22, nonmember $34; US, Canada and Mexico by First Class Mail: 52 RF By Zack Lau, W1VT 51 Next Issue in QEX ARRL member $35, nonmember $47; Elsewhere by Surface Mail (4-8 week delivery): ARRL member $27, nonmember $39; 56 Letters to the Editor Elsewhere by Airmail: ARRL member $55, nonmember $67. Members are asked to include their membership control number or a label from their QST wrapper when applying. In order to ensure prompt delivery, we ask that May/June 2000 QEX Advertising Index you periodically check the address information on your mailing label. If you find any inaccura- cies, please contact the Circulation Department Almost All Digital Electronics: 64 Nemal Electronics International, Inc.: 62 immediately. Thank you for your assistance. American Radio Relay League: 61 Noble Publishing: Cov II Copyright ©2000 by the American Radio Relay Astron: Cov IV Renaissance Radio: 61 League Inc. For permission to quote or reprint Atomic Time, Inc.: 62 Shoc: 63 material from QEX or any ARRL publication, send Communications Concepts Inc.: 62 Tucson Amateur Packet Radio Corp: 63 a written request including the issue date (or book title), article, page numbers and a description of Computer Aided Technologies: 8 TX RX Systems Inc.: 63 where you intend to use the reprinted material. HAL Communications Corp: Cov III Universal Radio, Inc.: 61 Send the request to the office of the Publications Manager ([email protected]) Roy Lewallen, W7EL: 62 May/June 2000 1 THE AMERICAN RADIO A RELAY LEAGUE R R Empirically Speaking L The American Radio Relay League, Inc, is a noncommercial association of radio amateurs, organized for the promotion of interests in Amateur Radio communication and experimentation, for A lot is happening in Amateur radio technology on their management the establishment of networks to provide Radio: licensing reform, discussions of spectrum and certification of communications in the event of disasters or other emergencies, for the advancement of radio art of new bands, expanded satellite equipment. In addition, interoper- and of the public welfare, for the representation operation, and so forth. We see fresh ability issues are raised. We will be of the radio amateur in legislative matters, and inspiration in many parts of the filing comments and we hope you will, for the maintenance of fraternalism and a high standard of conduct. experimental arena, too. Amateur too: This is important! Check it out. ARRL is an incorporated association without Radio has such diversity that it’s capital stock chartered under the laws of the difficult to find ways to give it all the In This Issue state of Connecticut, and is an exempt organiza- tion under Section 501(c)(3) of the Internal coverage it deserves. Goals for compression and radio Revenue Code of 1986. Its affairs are governed Some of you didn’t like the few transmission of digitized voice include by a Board of Directors, whose voting members relatively simple projects we ran last reduction in occupied bandwidth (bit are elected every two years by the general membership. The officers are elected or time. It is remarkable, though, how rate), improvement in quality or both. appointed by the Directors. The League is little is printed generally about AF Charles Brain, G4GUO, and Andy noncommercial, and no one who could gain through MF. Researchers are discov- Talbot, G4JNT, have taken the plunge financially from the shaping of its affairs is eligible for membership on its Board. ering some very interesting things into digital voice over Amateur Radio “Of, by, and for the radio amateur, ”ARRL about antenna system behavior and —and yes, it’s legal despite our numbers within its ranks the vast majority of wave propagation down there. Over erroneous warning. We shall listen active amateurs in the nation and has a proud history of achievement as the standard-bearer in the next year, we will bring you some with interest to hear of results over amateur affairs. of their results; we’ll also keep you up long-haul paths with their system. It A bona fide interest in Amateur Radio is the to date on progress in audio coding, takes advantage of the coding algor- only essential qualification of membership; an Amateur Radio license is not a prerequisite, compression and digital transmission. ithms that have been so successful in although full voting membership is granted only We have a nice collection of HF digital recording and broadcasting to licensed amateurs in the US. through microwave antenna articles in applications, distilled to the chip level. Membership inquiries and general corres- pondence should be addressed to the the queue, too. We’ll continue to Don’t be surprised to hear these signals administrative headquarters at 225 Main Street, emphasize advancement and under- on the HF phone bands before long. Newington, CT 06111 USA. standing of frequency-synthesis and My own approach involves many of Telephone: 860-594-0200 power-amplifier techniques. In this the same DSP principles, but it is Telex: 650215-5052 MCI MCIMAIL (electronic mail system) ID: 215-5052 issue, correspondents present both transmitted differently: as analog FAX: 860-594-0259 (24-hour direct line) background material and newly phone. Before committing to a specific Officers fashioned points of view on that last technique, I did a fair bit of research subject. Thanks to you writers and on auditory coding. I hope you find President: JIM D. HAYNIE, W5JBP 3226 Newcastle Dr, Dallas, TX 75220-1640 reviewers who were so patient while the results as interesting as I did. Executive Vice President: DAVID SUMNER, K1ZZ we got “up to speed” on it. Johan Forrer, KC7WW, presents a It seems like a good time to look tool that every serious student of The purpose of QEX is to: back on the legacies of QEX, Commun- propagation should want: a channel 1) provide a medium for the exchange of ideas ications Quarterly and before that, simulator. He begins with modeling and information among Amateur Radio experi- menters, ham radio. Now that those public- theory, then describes his practical 2) document advanced technical work in the ations are effectively consolidated, implementation and test results. Amateur Radio field, and we’d like to see the combination grow Much of this material appears in the 3) support efforts to advance the state of the Amateur Radio art. to be more than just the sum of its Proceedings of the 18th ARRL and parts. Ours is a unique opportunity to TAPR Digital Communications Confer- All correspondence concerning QEX should be addressed to the American Radio Relay League, build a better platform to document ence, Phoenix, Arizona, September 225 Main Street, Newington, CT 06111 USA. progress in our chosen field, celebrate 1999 (ARRL Order No. 7679), as does Envelopes containing manuscripts and letters for the accomplishments of our colleagues some of G4GUO’s. publication in QEX should be marked Editor, QEX. and sustain important discussions. L. B. Cebik, W4RNL, studies log- Both theoretical and practical technical articles Perhaps we should bring in additional periodic dipole arrays (LPDAs) in the are welcomed. Manuscripts should be submitted on IBM or Mac format 3.5-inch diskette in word- columns or news items. Maybe you first part of a series. He begins by processor format, if possible. We can redraw any would like to see more theoretical arti- looking at “short-boom” designs: 60-100 figures as long as their content is clear. Photos cles or instead, more practical appli- feet! As you can imagine, the next should be glossy, color or black-and-white prints cations. The balance we strike depends part will cover units requiring a of at least the size they are to appear in QEX. Further information for authors can be found on on you. Please drop us a line. bit more acreage. John Stephensen, the Web at www.arrl.org/qex/ or by e-mail to On March 21st, the FCC issued a KD6OZH, contributes the second [email protected].