[OZAPRS] APRS newbie, equipment recommendations

WILSON Jim Jim.WILSON at stanwell.com
Tue Jul 4 07:02:27 EST 2006


Hi,
I was after a dtmf encoder so that radios without a dtmf keypad could be
used by plugging the encoder into the speaker/mic port of the radio.
This would also enable me to predefine dtmf codes with a cheap PIC
interface.
Decoder chips are readily available so are not a problem.
P.S, is the code for APRStt available? I'm not much of a programmer and
I don't think I'll be able to help, but I'd like to learn how to
interface DTMF to a PC.

Thanks,
Jim 
 

-----Original Message-----
From: Robert Bruninga [mailto:bruninga at usna.edu] 
Sent: Monday, 3 July 2006 11:50 PM
To: ozaprs at aprs.net.au; WILSON Jim
Cc: Robert Bruninga
Subject: Re: [OZAPRS] APRS newbie, equipment recommendations

REgarding the APRS Touch Tone system, APRStt, the problem is, that I
wrote it in QBasic for DOS and so one has to add an external chip DTMF
decoder but read on...  You can use it without that if all you want is
the APRStt APRS==>Voice conversion.

I really never expected many people to do that, but what I DID expect
was that some windows progrmmer would write an all-software version
since a sound card can do ALL THREE required APRStt functions:
1) Decode the DTMF from DTMF users
2) Generate the Voice responses to the DTMF users
3) Communicate with PACKET on the APRS channel

APRStt fully defined all the formats using DTMF to send callsigns,
messages, positions, objects bulletins announcements, email etc...

APRStt really is a fantastic concept for APRS.  It simply turns EVERY HT
with a DTMF keypad into the full functional capabilities of the TH-D7
APRS ht by simply doing the keypad decoding (from DTMF) on the air at a
central APRStt decoder  instead of inside the radio.  This way EVERY ham
at an event can enter APRS positions, data and messages, etc.  Not just
those with a D7.

And then instead of a screen display, they get VOICE responses such as:

"LEAD was 3.5 miles north east of FINISH at 0909"
"W3XYZ was 4.5 miles south of the repeater at 0927"
"W3XYZ was 300 feet east of W4XYZ at 0930"
"Email received and forwarded"

This is all on a different LOCAL frequency than the APRS channel, yet
all of the DTMF radios can all talk to all of the APRS users via the
central APRStt engine.

http://www.ew.usna.edu/~bruninga/aprstt.html

Again, APRStt is fully funcaional under DOS and even without the DTMF
decoder, it can sit on a local VOICE channel and it can report once a
minute for example the position of any designated things to track.  SUch
as the lead and tail of a race event:

"LEAD is 4.5 miles from FINISH at 0909"
"TAIL is 9.2 miles from FINISH at 0908"

In APRStt, without a sound card for runnning on ANY old laptop, I
emulated a sound card with simply 8 resistors on the parallel port. Feed
to the MIC input of a radio and this gives APRStt its voice...

de WB4APR, Bob

etc...
>>> Jim.WILSON at stanwell.com 07/02/06 7:21 PM >>>
Thanks Bob,
Sounds good. I'll have to look into APRStt more. Should be good for some
other projects as-well.
Does anyone have schematics for a dtmf encoder? If I use this setup, I'd
like to interface with a picaxe so they can hit a button and the picaxe
will trigger a dtmf sequence. I'd like to be able to plug a dtmf encoder
directly into the mic input on the cheap uniden cb radios.
I'm still interested in getting some aprs running. So anyone's thoughts
or comments on their own set-up would be appreciated.
-----Original Message-----
From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] On
Behalf Of Robert Bruninga
Sent: Saturday, 1 July 2006 12:34 AM
To: ozaprs at aprs.net.au; WILSON Jim
Cc: Robert Bruninga
Subject: Re: [OZAPRS] APRS newbie, equipment recommendations

> I run scout camp where we break the camp up into four groups and they 
> walk from base to base throughout the weekend. I'd like a setup to 
> monitor their progress.
> What are my options regarding trackers...?

If this requires only 4 trackers, then this could work well as a high
tech solution.  But once you have APRS, there are usually far more
things you want to track and display....

SO, do not overlook the low-tech solution as well which is simply making
a map of the camp and "numbering" every interesting location.  THen just
the simple report of a "number" will update all APRS maps and displays
throughout camp with the current location of all participants.  This can
be done with voice, DTMF or a D7 HT. 

This track-by-points has been in APRSdos since 2002:

http://www.ew.usna.edu/~bruninga/D7points.html 

Using number-points reporting without GPS avoids these problems:
1) Keeping GPS units up and operating with all groups
2) GPS tracking problems in heavy foliage
3) Having to keep the GPS's running all the time and
    having to supply batteries for all that stuff
4) Erroneous positions due to erroneous GPS data
5) It works indoors and just about anywhere

This alternative is Someone with a radio in each group simply reports by
voice (or DTMF) "we are entering base #13", and the APRS  sysop simply
moves that group's object to location 13. 
This automatically then transmits that object to ALL APRS displays in
the camp so that everyone sees the movement.

This can be done automatically with APRStt.  The Touch-Tone version of
APRS that *any* HT can enter data with.  Just press something like XX*YY
on the DTMF key pad and the central APRStt will convert that to APRS
packet and update all APRS displays throughout the camp....

See http://www.ew.usna.edu/~bruninga/aprstt.html 

APRStt then also speaks voice information back to the DTMF-only users so
they also are informed on new reports such as "Team XX arrived at YY"...

And If you are running good APRS software that dead reckons, then it can
even show moving groups as they walk from base to base.  And the radio
consumes far less power than a GPS and radio together.  Plus ANY HT that
the scouts already have, including cheap FRS can be used.

Without APRStt, you can use the Kenwood D7 HT's either with GPS as
plug-and-play, OR they can be used without the bother of GPS as above,
by KEYING in the 2 digit number themselves and the internal TNC can
transmit it to all APRS monitors throughout camp without any human
intervention.

So many options... without the encumberance of GPS...

de WB4APR, Bob

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