SV: [FoxHunt] 2m transmitters required.

[Jon Sletvold]

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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