[GreenKeys] WRU and SELCAL

[Bob Camp]

Hi

As far as I can see this all would fit in a single PIC chip. The whole 
thing with connectors, level converters, and box would wind up about 
half a pack of cigarettes sized. It would be a pretty good project to 
do stand alone. I think you are right about not wanting a TTY running 
24 hours a day to do this. I think the same thing applies to other 
hardware as well. Keep it simple ....

	Enjoy!

		Bob Camp
		KB8TQ



On Apr 26, 2004, at 12:58 AM, Roy Norris wrote:

>
> 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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