FSK is RTTY but so is AFSK. Some rigs support the use of RTTY in FSK while others require a TNC or sound card to generate the tones. FSK on transceivers tends to invoke narrower filters and the frequency you are receiving is displayed differently. The serious RTTY guys tend to prefer FSK.
This post from the N1MM Logger reflector illusrates some issues.. (see also http://www.mcwa.org/AFSKvsFSK.pdf) Doug Haft wrote: > > Are you running AFSK, or FSK? Does this mismatch in frequency happen on > every spot, or randomly? If AFSK, which sideband, LSB or USB? I haven't > thought this trough, so I might be off base here, but its possible the > spotter is running AFSK. So, their rig is in USB (or LSB). Their audio > tones will be up (or down if using LSB) in the sideband. The freq on their > rig will be offset from where the "tones" really are. If you're running > FSK, you'll tune to the freq they spotted, but the target station won't be > there! Worse yet, if you're in USB running AFSK and the spotting > station is > in LSB AFSK... the spot he puts out will be quite a ways from where > you land > as a result of clicking that spot. > > > On Fri, Feb 19, 2010 at 3:58 PM, James French <w8...@wideopenwest.com>wrote: > > > Wondering if someone can point me to a link or some literature explaining > about why there is a FSK mode on the HF radios like the Icom ic-746pro, > Kenwood TS0940sat, and Ten-tec Paragon (585)? Is there a reason for this? > > I am asking this because I have listened to some RTTY using either USB or > LSB > dependent on what band I am on and could copy it with any software programs > I > have but then switched to the FSKmode on the radios and loose the signal > completely. > > Is this mode just for the older ancient RTTY eqiupment to interface with > the > radio? > > I haven't tried to send any RTTY yet but planning to be on the air next > weekend for the NAQP RTTY contest from the Red Cross station in Ann > Arbor,MI. > > James W8ISS > >
