Chris, here's a question for you. (I'm assuming that you are working
with FSK TTY.)

Is the classic 850-Hz shift still the current standard as it was during
the 1960s when I was still involved in TTY? I had thought that it had
been reduced to something like 75-Hz during the 70s due to the problems
with propagation path differences over a 850-Hz frequency spread.

Also, back in the mid-60s, it was sort of presumed that AFSK would soon
replace FSK... Did that ever actually happen?

By the way, in those days we tested our terminal units by printing NSS
transmissions for hour after hour. You could then visually scan down
the pages of printed code groups to determine how often your system
produced a glitch.

I was then among the more fortunate, because I owned a Model 26 TTY, a
model 14 Transmitter/Distributor, plus the holy of all holys, a Model
14 typing reperforator. Today all of these have been replaced by
computers! :-) Still, hearing those old machines hammer and click
away provided much more gratification than does a computer!

Have fun, Harry C.

wrote in message
oups.com...
Chris, here's a question for you. (I'm assuming that you are working
with FSK TTY.)

Is the classic 850-Hz shift still the current standard as it was during
the 1960s when I was still involved in TTY? I had thought that it had
been reduced to something like 75-Hz during the 70s due to the problems
with propagation path differences over a 850-Hz frequency spread.

Also, back in the mid-60s, it was sort of presumed that AFSK would soon
replace FSK... Did that ever actually happen?


I don't know when the 170 hz shift took over for most use. It was being
used about 25 years ago on the low bands for most of the users when I first
started rtty.

FSK is still all that is allowed on the low bands. Today it is generated by
using a SSB transmitter in the SLB mode and feeding in audio tones. This
generates a signal that is the same comming out of the transmitter as a FSK
transmitter. That is possiable due to the way a ssb transmitter works. If
the same rig was switched to AM or FM them it would be AFSK.

YOu can go here and download some programs that you can use on the computer
to do the digital modes. As I mentioned above by feeding the audio tones
into the mic or audio input of a ssb transmitter you will be generating FSK
eventhough it might not seem so.

http://www.muenster.de/~welp/sb.htm

One of the best free programs to get started with in rtty is the MMTTY
program.