[GreenKeys] WRU and SELCAL

[Roy Norris]

I have been searching the internet and old issues of RTTY Journal
looking for suitable designs for a WRU (answerback) and SELCAL design
that would serve our purposes for an auto start net.  While this could
be done on a PC, my thought is that most would not want to keep a PC
running continuously to provide that function.  WRU and SELCAL functions
can be provided in a model 28 stunt box arrangement however that
approach would require leaving the TTY machine on or the use of an
analog/TU  based autostart which are notoriously sensitive to false
triggers by noise or off frequency signals and carriers.
 
It seems to me that an ideal solution would be an external,
microcontroller based box connected to the TU via an RS-232 port that
would provide the following functions:
 
1.	PROVIDE DIGITAL AUTOSTART.  - monitor the RS-232 output of the
TU and when a valid digital signal is present, close a relay that would
turn on the teletype machine. Turn off the teletype machine when an
"NNNN" is detected.
2.	PROVIDE WRU CAPABILITY - monitor the RS-232 output of the TU and
when either the sequence "ZCZC"  or (callsign)ZW was received, close a
relay which would key the push-to-talk switch on a transceiver and send
the following string to the TU
    : " (20 diddles)(CR)(CR)(LF)(LF)(LTRS)(LTRS) DE (Callsign), (name),
in (location) (CR)(CR)(LF)(LF)(LTRS) NNNNN (CR)(CR)(LF)(LF)(LTRS)", 
     followed by turning off the relay which had activated the
push-to-talk switch.
3.	PROVIDE MULTIPLE SELCAL - monitor the RS-232 output of the TU
and when any of several individually selectable code sequences were
received, close a relay      that turns on the teletype machine.
Monitor for "NNNN" and turn off the relay that operates the TTY machine
when received.  Codes would include a) ones for receiving a message
directed at that particular station (possibly use the station callsign
as a selcal trigger). b) a code for receiving bullitiens  c) a code for
receiving "all-calls"..  Each code would be individually activated by a
front panel switch so that an operator could choose to receive or not
receive messages addressed to his station, messages that were bulletins,
messages that were "all-calls".
 
All of this capability has been incorporated in various devices in the
past so there is nothing new here.  I don't recall seeing it available
all in one external unit.
 
IIt would be wonderful if this capability could be incorporated in the
TTY Connect project currently underway by Gil Smith.  I believe he has
made provisions for an optional microcontroller on the board he is
developing but I am not sure the board is designed so that it could
provide these functions.  (What say, Gil??)  Alternative, a small
inexpensive stand alone box could be designed using a microcontroller.
If there is anyone on GreenKeys that has the necessary skills and would
be willing to undertake the project, please speak up.  
 
Alternatively, I will try and do it myself, although it has been 20
years since I did any programming of this nature and it was on 8085
computers, not microcontrollers.  But I guess I could get back up to
speed in a couple of months.  It would be tremendously helpful if I
could locate any of IRV Hoff's source code for his RMON program or his
standard teletype program that was use on the 20 meter autostart
frequency of 14.0875 Mhz.  Does anyone on the list have this or have an
idea of where I might find it??
 
I have looked at the aforementioned RTTY12 program.  It is written in
Basic and has selcal but no WRU that I can find.  Irv Hoff's code would
be the best if we can find it.  I hate that I threw away my copies some
years ago.
 
Thoughts?  Suggestiohns ??  Ideas, pro and con ??
 
Best regards - Roy Norris, K4EEG


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