From: utzoo!decvax!harpo!ihnp4!ihps3!houxz!houxi!houxp!ad7i Newsgroups: net.ham-radio Title: AD7I AMTOR Report to the FCC (long) Article-I.D.: houxp.163 Posted: Mon Dec 6 11:13:54 1982 Received: Tue Dec 7 10:18:47 1982 ad7i msg 26: A report that i submitted to the FCC on a HF RTTY error correcting protocol follows. ------- Thirty Victoria Place Red Bank, N.J. 07701 201-949-3731 (W) 201-741-1151 (H) November 23, 1982 Mr. Richard H. Everett Chief, Licensing Division Federal Communications Commission Gettysburg, P.A. 17325 Dear Mr. Everett: Enclosed is the report required by the S.T.A. outlined in your letter of May 3, 1982. If I can provide any additional information, please do not hesitate to contact me. Sincerely, Paul Newland Copy (with att.) to Vic Clark, W4KFC Phil Karn, KA9Q Bill Meyn, K4PA Dave Sumner, K1ZZ Curtis Williams, W5DTR netnews November 23, 1982 REPORT TO THE FEDERAL COMMUNICATIONS COMMISSION ON EXPERIMENTS CONDUCTED BY PAUL NEWLAND AT AMATEUR RADIO STATION AD7I USING THE ERROR CORRECTING PROTOCOL DESCRIBED BY CCIR RECOMMENDATION 476-2 ABSTRACT This report outlines the use of the teleprinter code described by CCIR Recommendation 476-2, also know as AMTOR, by amateur radio station AD7I. Use of this code during the period provided by Special Temporary Authorization (S.T.A.), file 7130, was hampered by external influences. No "scientific" data were collected but outstanding performance provided by the CCIR 476-2 coding was observed by the operator on numerous occasions. The report concludes with a recommendation that use of CCIR 476-2 coding by U.S.A. radio amateurs be allowed as soon as possible. DISCUSSION This report describes use of the error correcting protocol described by CCIR Recommendation 476-2 at my amateur radio station, AD7I, during the period of May 1982 to November 1982. During much of the experimental period, the High Frequency (HF) station was inoperative because of radio problems. Additionally, I was required by business commitments to make several unexpected and lengthy trips during the fall. Consequently, time did not permit scientific data, per se, to be collected for presentation. However, I have formed strong opinions about the usefulness of this mode of communications based on my use. In May of this year I completed construction of a microprocessor system to convert the CCIR 476-2 signals to international telex teleprinter code. The firmware to accomplish this code conversion was provided by Mr. Peter Martinez, G3PLX; I designed the controller to be software compatible with Mr. Martinez's firmware. An additional microprocessor system was designed and built by me using a different manufacturer's microprocessor. I programmed this second microprocessor to convert CCIR 476-2 Mode B to international telex teleprinter code. I also purchased a new HF-SSB radio to perform experiments with CCIR 476-2 coding. All other equipment was previously on hand. After completing the controllers, U.S. Coast Guard and Canadian Coast Guard weather broadcasts were monitored to observe the print quality of Forward Error Correction (FEC) mode B communications during normal HF propagation conditions. In my opinion, without scientific data to back my - 2 - claim, I feel that the FEC mode of operation for broadcast use is superior to that of conventional stop-start unprotected teleprinter transmissions (RTTY). A major advantage of CCIR 476-2 coding in FEC mode is that detected errors are converted to space characters by the code converter. Hence, errors are easily and quickly spotted by the operator so fills can be made from context. On June 1, 1982, I advised the Commission's field office that on or after June 11, 1982, station AD7I would begin transmissions using CCIR 476- 2. On June 13, 1982, contact was established with station TI3DJT using the Automatic ReQuest for repeat (ARQ) mode A. From June 13 to 29, 1982, 39 contacts were made with radio amateurs around the world using CCIR 476-2 coding. Most of the contacts were made with ARQ mode A; only several contacts were made using FEC mode B. All contacts took place on or near 14.075 MHz. Stations with which communications took place were: TI3DJT, PA0RYS, HB9AUK, HB9AK, K4PA, G3PLX, A4XFW, G3RYS, KB6BT, KC7KK, and TI2CC. On June 30, 1982, the station's radio was returned to the manufacturer for repair under warranty. The synthesizer provided unreliable operation after the radio had been on for several hours. On September 28, 1982, the radio was returned in good working order. >From September 28, 1982, to November 14, 1982, another 31 contacts were made. In my opinion, again without scientific data to back my claim, performance using CCIR 476-2 ARQ coding is VASTLY superior to conventional RTTY coding. CCIR 476-2 displays an amazing robustness during conditions of propagation that render SSB and CW modes of communications virtually useless. I apologize for not having scientific data to back my claims; I am sure that the data would substantiate my opinions. CCIR 476-2 consistently provided communications during short and long duration frequency selective fading, during SSB and CW co-channel and adjacent channel interference, and during conventional Radio Teleprinter (RTTY) interference. The only interference to which CCIR 476-2 is not immune, as one might expect, is another co-channel CCIR 476-2 station. Such stations did not present much of a problem during the test period. However, it is important to note that there were few stations available to cause inadvertent or deliberate interference. IMPLEMENTATION CCIR 476-2 proves to be a simple addition to an amateur radio HF RTTY station. Figure 1 shows how the system components were configured at station AD7I. The cost of the CCIR 476-2 code converter was about $40.00 due to a well-stocked junk box. If all components for the controller were purchased new and the firmware was free, the cost for a code converter should still be well under $85.00. This is a small amount of money compared to other system components. Vast sums should not be required to implement a CCIR 476-2 code converter. - 3 - CONCLUSION The performance provided by CCIR 476-2 coding is superior to conventional coding, and the incremental cost to add that capability to an amateur radio RTTY station is low. I therefore recommend that the Federal Communications Commission allow, as soon as possible, the use of CCIR 476-2 coding by radio amateurs who now have RTTY privileges. Respectfully submitted, Paul Newland, licensee of Amateur Radio Station, ad7i