ST NOALL @ ALLMSG < NN0ASU $1064_NN0ZLS MT63 OPS R:050311/1748Z @:NN0MDW #:697 R:050311/1641Z @:NN0MDU #:76 R:050311/1618Z @:NN0MDH #:1311 R:050311/1444Z @:NN0MDV #:520 R:050311/1512Z @:NN0MDR #:1181 R:050311/1506Z @:NN0MDQ #:1064 RR NOALL DE NNN0ASA 025 R 111500Z MAR 05 FM NNN0ASA VA TO NNN0ALL BT UNCLAS SUBJ: OPERATIONAL EXPERIENCE WITH MT63 1. THE FOLLOWING ATTEMPTS TO SUMMARIZE MY PERSONAL LONG TERM OPERATIONAL EXPERIENCES WITH MT63. IT IS TRANSMITTED FOR INFORMATION TO, HOPEFULLY, ASSIST YOU IN YOUR LOCAL OPERATIONS. PLEASE KEEP IN MIND THAT SOME THINGS THAT WORK HERE MAY NOT WORK WHERE YOU ARE AND VICE VERSA. 2. MT63 IS STARTING TO REPLACE RTTY AND AMTOR FEC AS THE TRAFFIC BROADCAST MODE WITHIN NAVY-MARINE CORPS MARS. THERE ARE SEVERAL REASONS FOR THIS: A. MT63 SOFTWARE IS AVAILABLE FOR FREE. ADVANCED PROGRAMS FEATURING MT63 AND OTHER MODES ARE AVAILABLE FOR A NOMINAL FEE. B. MT63 DOES NOT REQUIRE PURCHASE OF A SEPARATE TERMINAL NODE CONTROLLER (TNC) (400 DOLLARS OR MORE). C. MT63 PERFORMS BETTER UNDER POOR PROPAGATION CONDITIONS. D. SIMULTANEOUS MT63 AND VOICE/AMTOR TRANSMISSIONS ARE POSSIBLE WITHOUT LOSS OF DATA. E. MT63 PLACES LESS WEAR AND TEAR ON TRANSMITTERS DUE TO LOWER AVERAGE POWER. 3. EVEN WITH ITS ADVANTAGES, MT63 HAS ONE GLARING DISCREPANCY IN THAT IT IS NOT CAPABLE OF DIRECTLY INTERFACING WITH THE MARS DATA SYSTEM (MDS). IF NOT ABLE TO CONNECT WITH A VHF PACKET MESSAGE SWITCH DIRECTLY, A STATION WITH A PACTOR OR AMTOR CAPABLE TNC IS REQUIRED TO INPUT TRAFFIC INTO THE MDS. (NNN0BOK IN IS WORKING ON DEVELOPING AN ARQ LIKE VERSION OF MT63.) 4. CERTAIN PREREQUISITES ARE NECESSARY TO OPERATE MT63 EFFECTIVELY: A. FOREMOST, THE MT63 USER MUST HAVE A SOUND CARD EQUIPPED COMPUTER FAST ENOUGH TO HANDLE THE MT63 PROGRAM (PENTIUM 200 MHZ OR BETTER). B. FOR A RECEIVE-ONLY STATION, ONLY A CABLE FROM THE SPEAKER OUTPUT OF THE RADIO TO THE MICROPHONE INPUT OF THE COMPUTER IS REQUIRED. (MOST RADIOS WILL PROVIDE TOO HIGH A SIGNAL TO THE COMPUTER SO A MEANS OF ATTENUATING THE SIGNAL IS NEEDED TO PREVENT OVERDRIVING THE SOUND CARD INPUT.) C. FOR TRANSMIT CAPABILITY, AN INTERFACE SHOULD BE USED TO ISOLATE THE COMPUTER FROM THE RADIO. ONE CAN BE BUILT RATHER EASILY OR PURCHASED INEXPENSIVELY. D. THE COMPUTER SOUND CARD ERROR MUST BE KNOWN SO IT CAN BE CORRECTED. (LARGE SOUND CARD ERRORS WILL PREVENT COPY OF MT63 CORRECTLY). THE TWO MOST OFTEN USED MT63 CAPABLE PROGRAMS (IZ8BLY MT63 (FREE) AND MIXW) PROVIDE A MEANS TO CORRECT FOR THE ERROR. FOR THE MT63 PROGRAM, DOWNLOAD THE FREE MMSSTV 1.11 PROGRAM AND USE THE SETUP PROCEDURE TO DETERMINE THE SOUND CARD ERROR AND APPLY IT IN THE CONFIGURATION PORTION OF MT63. MIXW HAS ITS OWN PROCEDURE FROM WITHIN THE PROGRAM. 5. MT63 HAS THREE SPEEDS BASED ON THE BAND WIDTH USED: A. 2000 HZ (500 HZ TO 2500 HZ) - THROUGHPUT 200 WPM B. 1000 HZ (500 HZ TO 1500 HZ) - THROUGHPUT 100 WPM C. 500 HZ (500 HZ TO 1000 HZ) - THROUGHPUT 50 WPM 6. IN ADDITION TO THE BANDWIDTH, THERE ARE THREE CHOICES FOR THE INTERLEAVE USED IN THE WALSH FORWARD ERROR CORRECTION SCHEME INTEGRAL TO MT63: A. LONG INTERLEAVE B. SHORT INTERLEAVE C. VERY SHORT INTERLEAVE 7. THE FOLLOWING TABLE COMBINES THE OPTIONS ABOVE AND SHOWS HOW LONG IT TAKES FOR THE INTERLEAVING TO COMPLETE SENDING ONE CHARACTER. EACH CHARACTER IS SENT ON EACH OF THE TONES (0 TO 63) AND SPACED IN TIME, THE INTERLEAVE. (THIS SCHEME ALLOWS FOR 16 OF THE 64 COPIES OF EACH OF THE CHARACTERS TO BE RECEIVED INCORRECTLY BUT STILL HAVE THE ACTUAL CHARACTER COME THROUGH WITHOUT ERROR) (READ IN FOUR (4) COLUMNS): BANDWIDTH INTERLEAVE CHARACTER RATE TIME FOR 1 CHARACTER 500 HZ LONG 5 CHAR/SEC 12.8 SEC 500 HZ SHORT 5 CHAR/SEC 6.4 SEC 1000 HZ LONG 10 CHAR/SEC 6.4 SEC 1000 HZ SHORT 10 CHAR/SEC 3.2 SEC 2000 HZ LONG 20 CHAR/SEC 3.2 SEC 2000 HZ SHORT 20 CHAR/SEC 1.6 SEC NOTE: VERY SHORT INTERLEAVE BASICALLY DOES AWAY WITH THE FORWARD ERROR CORRECTION. THIS COULD BE USED FOR KEYBOARD-TO-KEYBOARD OPERATIONS WHERE SOME ERRORS ARE ALLOWABLE. 8. THIS GIVES MANY CHOICES AND CAN CAUSE CONFUSION IN OPERATING IF A DEFAULT IS NOT SPECIFIED. NAVMARCORMARS HAS DEFINED THE PROGRAM DEFAULTS (IZ8BLY MT63 AND MIXW) OF 1000 HZ BANDWIDTH USING LONG INTERLEAVE. START IN THIS MODE AND THEN MUTUALLY AGREE TO SHIFT TO ANOTHER OF THE MODES. 9. BASED ON EXPERIENCE HERE IN THE NORTHEAST AREA WHERE I OPERATE, I RECOMMEND THE FOLLOWING SETTINGS TO MATCH OPERATING CONDITIONS TO SEND RECORD TRAFFIC. A. AVERAGE CONDITIONS - USE THE DEFAULT, 1000 HZ, LONG INTERLEAVE B. EXCELLENT CONDITIONS - 2000 HZ, LONG INTERLEAVE C. LONG STATIC BURSTS - 500 HZ, LONG INTERLEAVE (LIKE SUMMER THUNDERSTORMS OR VERY LONG PERIODS OF FADING) 10. IF YOU HAVE OTHER OPERATIONAL EXPERIENCES WHERE YOU LIVE, PLEASE SEND THEM TO THE MEMBERS IN YOUR AREA, INFO YOUR CHAIN OF COMMAND, SO THAT WE MAY ALL LEARN FROM YOUR EXPERIENCES. 11. NAVMARCORMARS: PROUDLY SERVING THOSE WHO SERVE. BT NNNN /EX