The decoders operate on the demodulated tones. For RTTY there are two
tones for 1 and 0. You need the radio to generate these tones by
operating in SSB mode (usually USB).

thanks. Now I know to get a working shortwave radio with SSB capability before
getting a RTTY decoder.

In article ,
Stereophile22 wrote:
The decoders operate on the demodulated tones. For RTTY there are two
tones for 1 and 0. You need the radio to generate these tones by
operating in SSB mode (usually USB).

thanks. Now I know to get a working shortwave radio with SSB capability before
getting a RTTY decoder.

Just be aware that, if you want to get serious, you will have to get
a fairly high performance receiver, (on the par with an Icom R-75 or
the like). The maritime TOR stuff is narrowband shift (170? Hz) and the
channels are closely spaced (1/2 kHz).

I use(d) an Kenwood R-1000, which is designed mostly for audio broadcast,
and found that the 2.1 kHz narrow bandwidth (SSB) filter was often a bit
too wide and that the tuning drifted just a bit too much (maybe 50 Hz) so
that you had to babysit it to get solid copy.

Mark Zenier Washington State resident