[GreenKeys] Re:I hope you can help. Jan Bogue KD6EMW W15 page printer with perf

[gil smith]

Hi Jan:

Yes, you need a unit called a TU (Terminal Unit) which demodulates the fsk 
data from the radio and converts it to a signal that keys a tty loop.  Some 
TUs can key a loop directly, while others output RS-232.  A bunch of us on 
the list got Dovetron TUs about a year ago, which have 232 output.  You can 
connect a pc with the appropriate terminal-emulation software to see this 
rs-232 stream, or you can connect an RS-232-to-current-loop adapter.

You can also get a pc program that eliminates the TU/TTY, such as 
MMTTY.  The audio output from your radio feeds into the line-input of the 
PC sound card, and the program decodes and displays the messages (with 
appropriate adjustments, of course).  This is a good way to fine-tune your 
radio/antenna, before connecting a real TU and TTY.

As for phone lines, yes, you could use a pair of old 300-baud computer 
modems.  The tty is not 300-baud of course (60-wpm = 45-baud), but these 
modems just use fsk, so they have no minimum bit time.  You would need to 
issue the appropriate Hayes commands (AT...) to one modem to place it in 
auto-answer mode, and commands to the other modem to dial the appropriate 
phone number.  This is a bit complicated, since the commands to the modem 
need to be 300-baud ascii, but it could be done.

gil

At 07:46 PM 11/7/2004, Wndrrt at cs.com wrote:
>Just Jan again Gil.       So....Do I need to build my on demodulator and
>modulator to handle the signals from these old machines and deliver them 
>to and
>from my ham radio?  You don't just hook the teletype up to your radio 
>without a
>go between do you.  Next question.  Can you hook the teletype machine 
>directly
>up to a phone outlet and communicate with someone else using the same type of
>machine let us say down the street or across the nation?  Or do you need
>another type of go between circuit? I am in grade one at this stage, so the
>questions may sound a little basic.  Thanks,  Jan on the starting to rain 
>desert in
>southern cal.
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>GreenKeys mailing list
>GreenKeys at mailman.qth.net
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