Jon, Here in WPA we've adopted MT63 2k long (64 bit) interleave as our standard. The mode is very wide (2000hz) but fits very nicely inside the typical FM transceiver and repeater audio passbands.
Here's some of the big advantages of MT63 2k long on FM: -Massive amount of FEC (forward error correction) and interleaving provides perfect copy, even under horrendous simplex conditions and weak signals into repeaters (it even barrels through short drop-outs and heavy noise with weak stations into our local UHF repeater) -There's no need to have to tune on the waterfall as all MT63 submodes in FLDIGI are fixed at a bottom waterfall frequency of 500hz (2k long goes from 500 - 2500 on the waterfall) -WPM rate is about 200wpm -Works fine using only a hand mic on the computer speaker and the computer mic somewhere in the vicinity of the received audio from the transceiver We run over UHF/VHF traditional voice repeaters and simplex frequencies with great success on our net every week... even with first time users. Please give it a shot and let us know how you make out. Also, make sure your ops do a proper sound card calibration. You only have to do this once, unless you change your sound card or switch to a USB mic. Here's a video I made on that subject of calibration using CheckSR.exe and FLDIGI: http://www.utipu.com/app/tip/id/9382/ -Dave, KB3FXI www.wpaNBEMS.org --- In digitalradio@yahoogroups.com, "JonP" <jpere...@...> wrote: > > I have the need to set up some reliable local digital communications (say 10 > mile radius from the base station) for data transfer, and to do so in a short > period of time. > > I would normally first think of VHF FM packet, but a lot of people are > running into troubles with things like Vista and Windows 7 (please, spare me > the "Linux" or "Apple" and "D*Star" messages, they're not realistic in this > situation). > > I've seen some references to running DominoEX and MFSK-16 on VHF FM. A > number of my prospective operators are running digital modes such as > DominoEX, MFSK, etc. on their computers now (under XP, Vista, Win7) without > problems. > > Would one of those modes be realistic to run on 25 watt (or higher) mobiles > on 2 meter FM using vertically polarized antennas? I realize that the > vertical polarization would be an issue if we want to get out of the local > area, but right now the need is within a local area and everyone would be > running with a typical VHF vertical. > > If feasible, what sub-band would we use? I would assume the FM simplex > sub-bands. Is that correct? > > Anything else we should consider? Any special issues/problems? I would > think that we would not have to reduce power since these radios are already > running FM, but if not the case please correct me. > > Thanks. > > Jon > KB1QBZ >
