[FoxHunt] 2m transmitters required.

Mon Mar 21 23:49:54 EST 2005

 Jon,

The scripting idea sounds very interesting and would make it a very flexible
transmitter. Both I and Mike like that idea. Mike is going to take a look at it
to see what it would take to make a system like that. Most likely it would be a
basic like language of a few keywords. Will get back with you on what he finds.

The hardware platform that we designed has a real time clock that runs when the
main battery is removed. So some version of delayed start is possible. Also if
main battery power is interrupted while its being transported to the field the
system will auto recover when power is restored and will stay in sync.

Our plan is to set the clock in our system by plugging in a GPS. When the
software detects a NEMA data stream it will automatically check the real time
clock to see if it needs to be resynchronized with GPS time. 

There will be a RS232 commend system where the operator could use a PDA such as
an IPAQ or a laptop with a terminal emulator to configure the transmitter. 

The operating software will look at who the transmitter is configured to
(MOE-MO5 or MO) and schedule its transmission based on the real time clock (The
first minute of the hour is defined as MOE). There will be no dip switches as
all configuration will be via the RS232 port and saved to NV memory.

Our first version will be to get it functional for the championships this summer
with ARDF functions, but we are collecting a list of other functions that would
be nice for use beyond that event. 

For example car type hunts may want a fox that can come on at random times at
different power levels each time it comes on. 

Where ARDF needs the MOE - MO5 format. Radio -O may want ultra low power
transmitters. In our design the power level is software controlled on both HF
and VHF. Just finished testing the HF pa and was able to very its power.

I noticed that the ARDF transmitters used at the word championships sent a long
tone at the end of the cycle. I'm assuming that that's common in Europe.  In the
US our transmitters have to send the call sign to meet our FCC rules. That's
where your scripting idea would be real nice.

73's

Jerry

-----Original Message-----
From: foxhunt-bounces at mailman.qth.net [mailto:foxhunt-bounces at mailman.qth.net]
On Behalf Of Jon Sletvold
Sent: Thursday, March 17, 2005 1:24 PM
To: 'wb8wfk at worldnet.att.net'; 'Radio Direction Finding'
Subject: SV: [FoxHunt] 2m transmitters required.

Hello, Gerald and Mike

Thanks for a quick answer, and I'm sorry I'm late with an answer. I'll find it
interesting to hear about the TX project.

The general foxhunt transmitter has normally only a few options, as setting
transmitter cycles and number. I would like a little more sophisticated
transmitter that could be programmable with some kind of internal scripting that
allows the transmitter to alter different modes. The scripting option allows the
transmitters to be used with different country specific options without the need
to change the firmware.

The different modes of a transmitter could be:

Programming mode: A computer is used to program the transmitters with a
dedicated program that configures the transmitters correctly. The general
problem with toggling and push button programming is that the user makes
mistakes and there are no indications that there are problems until the
transmitters starts (or don't). A computer-based system would verify that the
set-up is correct. A USB or RS-232 connection to a computer is required.

Idle mode, transmitters are in sleep mode waiting to start. A very exact
oscillator should allow the transmitters to be deployed 24h before the
competition without an annoying timeslip between the transmitters. This requires
a 2 to 3 ppm TCXO oscillator. They are expensive if it's not possible to find
mass produced components that could be used.

Transmitting mode are the period when the transmitters are supposed to be
operating until the competition is over.

A training mode starts with a home beacon that starts 15 min before the other
transmitters and countdown to start. The training course could then be operating
for a period of time, switch to idle for a defined time and go back to training
mode.

"Find me beacon" is an option to collect the transmitters after the competition.
This could be short sequence beep that the collector can use instead of waiting
4 minutes before the transmitter starts again.

Cycles should be configurable, also signatures and sending pattern. This is also
possible with a internal scripting in the transmitter.

I think this is not an easy task. I don't know the platform you have designed
the transmitter on, but a SDR is usually based on a single chip DSP and could do
this job as it's not time consuming functionality. The drawback though is that
the software must be designed and It's time consuming.

I hope this might have given you some ideas.

73 de Jon LA9NGA

-----Opprinnelig melding-----
Fra:	gerald boyd [SMTP:wb8wfk at worldnet.att.net]
Sendt:	09 March 2005 05:09
Til:	'Radio Direction Finding'
Emne:	RE: [FoxHunt] 2m transmitters required.

Jon,

Myself and Mike, K5ATM have been working on an DDS based software defined ARDF
transmitter.

On march 5th our prototype exciter was demonstrated at the Albuquerque Amateur
Radio Club meeting.

This hardware was a functional 2 band ARDF exciter that can generate CW on 80
meters. On VHF (2 meters) it has the following modulation modes; MCW AM, keyed
carrier MCW AM, MCW FM and keyed carrier MCW FM. (MOE,MOI,MOS,MOH,MO5 and
MO) We
have also demonstrated other modes such as packet radio data transmission.

It also has a simocast mode for practice sessions (80M and VHF at the same
time).

Forgoing any development problems we hope to use the transmitters during the
Region II ARDF championships this summer. Our event website is
http://www.ardf.us Registration for the championships just opened this weekend.

We have been sending out progress reports about the transmitter on our two local
list servers ABQTHUNT and ABQARDF.

Our project is currently in the advanced stages of development as we have
demonstrated basic operation with the first generation development hardware. All
that is required is to add the power amp stages and final version of the
operating software and spin the circuit board design.

What additional functions or features would you like to see in an ARDF
transmitter?

73's

Jerry WB8WFK

-----Original Message-----
From: foxhunt-bounces at mailman.qth.net
[mailto:foxhunt-bounces at mailman.qth.net]
On Behalf Of Jon Sletvold SICI
Sent: Tuesday, March 08, 2005 12:58 AM
To: Radio Direction Finding
Cc: Mohd-Ayub.Suhaili at shell.com
Subject: Re: [FoxHunt] 2m transmitters required.

Hello.

I think the only "out of the box" ARDF transmitter available are from ok2bw.
There are kits available, but they need to be assembled. Perhaps others on this
list can add some information. The products are available from:
http://www.marecek.sky.cz/

The Norwegian ARDF association is also looking for transmitters, and I've done
some research using a microcontroller (PIC or ATMEL), a stable TCXO
(1ppm) and a DDS to design a 80m ARDF transmitter. The goal is to make light
weight transmitters that are fully configurable from a computer (not online in
the forest though!) and can be deployed in the field for a week and start and
stop at the desired time. This will allow us to have training course that can be
operating for several days, but also allow smaller batteries to be used as the
transmitters are only operating during the competition time.

What I need is more people to join in with this project in order to share
working load and reduce the "time to market". It's also a good idea to get
people with different experience or occupation as HW designers, SW designers,
mechanical engineers. I'm my self a HW engineer with a little SW and VHDL
experience. Are there any one else who might be interested and would join this
project?

Regards Jon / la9gna

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