Hi Cortland, 73, Skip KH6TY http://kh6ty.home.comcast.net ----- Original Message ----- From: Cortland Richmond To: digitalradio@yahoogroups.com Sent: Wednesday, March 25, 2009 7:46 PM Subject: Re: [digitalradio] Contestia / MT63 Skeds pse
Hello Skip! There are too many choices, which is one reason I lurk here picking the brains of people who have evaluated a lot of them. Which of the many digital modes ends up as MARS standards must be decided by the State, Region and Service MARS directors. I have heard MT63 2000 Hz, 1000 Hz and 500 Hz (all long interleave), Olivia 32, 16 and 8 tone, and MFSK 8 and 16 (IIRC) tone -- at different center audio settings for different Service's MARS. Some months ago I heard a MARS net running AMTOR. Tonight in Michigan we were experimenting with Domino EX 11 tone. I will say that we here in Michigan Army MARS are presently using MT63 1000 at 100 Hz center, with 2000 Hz (1500 Hz center) for especially large messages or files, and for weak signal work, Olivia 32 and 16 tone at 1 KHz center frequency. Roger, we are using MT63-1000 here for MARS but the latency is too much for net callup, so something like MFSK16, DominoEX 8, or Olivia will reach weaker stations better. The jury is still out as to what to recommend to use. DominoEX 8 is still fast enough for net callup but more sensitive than DominoEx 11. No reason to use a less-sensitive mode for net callup I think. It seems most of us, MARS or Amateur, don't put the harmonics of our tones outside the IF filter passband. On the other hand, modern rigs don't seem (from my waterfall) to produce much. Does not seem to be a problem here either. 73, Skip KH6TY/NNN0VFAT Cortland KA5S/AAR5UT ex AAR9UT, AAR6QC (1990's) and other calls
