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WLO was one of the old ship-to-shore radio stations. For FSK, I use MMTY.Ĭlick to expand.It's in the old 8 MHz marine band, more or less, isn't it? (Yes, I have a trouble ticket open and they are working on it). DM780 will do FSK, but I honestly can not recommend it since it still needs a little work. As above, this won't work if you are chasing signals all over the waterfall.Īlso, when the radio is in RTTY mode, it transmits using true FSK (frequency shift keying) only, not AFSK (audio frequency shift keying). When TPF is invoked, the radio boosts the signals at 2125 Hz and 2295 Hz specifically to improve the ability to copy RTTY signals. The other dedicated RTTY filter is called TPF or Twin Peak Filtering and this is what makes it all worthwhile (to me anyway). So as you can see, you really can't use the dedicated RTTY filters if you are going to click anywhere on the waterfall for RTTY signals. Of course I would never set the SSB filter to 500 Hz for voice work, I just made it that narrow for clarity. To make this (hopefully!) a little easier to visualize, here are screen shots of the DM780 waterfall: Remember, the mark and space tones for RTTY are 170 Hz wide with the Mark being 2125Hz and the Space at 2295Hz (I had these two reversed in my comment above) thus making 2210 exactly in the middle. However, the RTTY filters are centered around 2210 Hz. And actually, the radio has two SSB modes, one for voice and one for digital so this can be very helpful for the soundcard modes in addition to FSK RTTY.īut since you asked about RTTY specifically, when you are in SSB (normal or digital) and you progressively narrow the passband filters, the passband gets narrower by cutting off the outside edges equally from both sides centered on 1500 Hz. The first reason is that the radio allows you to have three IF passband filters for each mode (except for FM) with the width of each being adjustable. Click to expand.I bought (yet another) Icom radio because of its dedicated RTTY filters (among other things).