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Terry

Auto Tracking Aerial

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I just checked the rotation rate for anyone that may be thinking of building one of these. Mine is doing 12rpm thats 72deg per second. I think a faster rate may be better but I dont know as I have not tried it. Anyway this gives you a known starting point.

Terry

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Just added a dust cover to keep the dirt out, mostly rain just now.

Not sure how much it effects the range but it seems ok, if I get desparate it will unclip in a few seconds..

Terry

post-6-1090941561_thumb.jpg

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Here is the HEX code for the 16c71, there is no fuse info included as my old programer dose not support it. Its running at 4mhz with no wdt.

A1 = RSSI

A0 = THRESHOLD SET POT

B0 = MOTOR RIGHT

B2 = MOTOR LEFT

B4,B5,B6 & B7 connect to a dip switch to set sweep and delay

B7 = SWEEP ANGLE

B6 = ADD SHORT DELAY

B5 = ADD MEDIUM DELAY

B4 = ADD LONG DELAY

B4,5 & 6 can be use to give delays between sweeps of about 1.5sec to 8.5sec.

Note the RSSI needs to drop voltage as the signal gets stronger for this to work.

I would aim for a rotation speed of between 10 & 15rpm.

Terry

ATrk3.HEX

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I have been asked for the cct for this project so I drew out the circuit that I used in the prototype. It can I am sure be improved on ( I have a few ideas myself ) but here it is. It is tried and tested for the 150mA motor I am using but a more powerfull 'H' bridge will need to be added for big motors.

Terry

post-6-1091967778_thumb.jpg

Edited by Terry

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Just bumping up this thread. I am still looking for information on building a tracking antenna based on the GPS co-ordinates of the airplane.

Thanks,

-dave

Edited by dalbert02

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Ive had 2 guys contact me for more info on this in the last couple of weeks so Im posting some pictures to try and help. If anyone else is interested the aerial works best on planes that fly level (no aerobatics) at distances over 1000ft. Aerobatics confuse the simple signal strength compare way of operating it uses. Aircraft closer than 1000ft tend to either move too fast for the tracking to keep up or too high to get a good signal. At distances over 1000ft I have never had a problem at any hieght. There have been a few upgrades to to hardware and software since I started but the code and hardware shown work fine. Please note to keep the code and harware simple I have used a DC geared motor not a stepper motor and a simple slip ring made from a stereo jack plug and socket so as not to have problems with wires getting tied up.

post-6-1145785884_thumb.jpg

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Terry

Thanks for posting the pictures. I am starting to work on my auto tracking antenna this week.

Please excuse my lack of knowledge but can you please advise what is connected to pins 15 and 16 on the pic in your drawing.

Also is there any changes that you recommend making while I am building it.

Any help or suggestion are muchly appreciated.

I will be using the RC -Cam Goof Patch antenna.

Thanks

Crash Pilot 1

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Pins 15 and 16v are connected to the 4Mhz resonator.

Recomended changes .. Hmmm.. The only thing I wound add first off is to make an amplifier to scale your RSSI signal to use as much of the 0 to 5v input as possable. Dont burn a OTP chip for this as I will help you fine tune the code when you get it working.

Terry

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Thanks Terry

I will start building the turn table this week and post the pictures of my progress. Thanks for offering your help when it come to the fine tuning I will surely need it.

Thanks again

Crash Pilot 1

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Terry

Started the turntable today. Have all the pieces done just have to file and polish them. Getting the turn rate was the hardest. The best-geared speed I could achieve was 14 turns at the gearbox shaft. Because the motor has to be offset from the centre due to the stereo jack being used for the slip rings I had to turn up some miniature pulley's on my fathers lathe with a 1:1 ratio so that I could offset the geared motor.

I will be using a large o-ring for the belt.

One problem I also had is that I will need the try and run audio as well which means the stereo jack is short one slip ring (has 3 when 4 is required).

To over come this I turned up a plastic collar to insulate the negative part of the male stereo jack from the alloy base. Then I will use the alloy base as the negative and make an external slip ring by using the alloy-rotating disk that the patch sits on and a spring tensioned drill motor brush that is fitted to the base. Because the female part of the stereo jack has a plastic thread it is already insulated from its mounting point. So if this works it will give me 4 slip rings, which will be need for the audio channel as well.

Is the PIC16C710-04/P (Farnell Part No 96243) suitable for this project? It is the only one that is available?

Max 4427 (Farnell Part No 29536)

I think I have narrow down which resonator is required but I am stuck with the final pick. If possible can you please advise which one on the attached file is suitable?

Also in your last post you mentioned about the opamp. Is this worthwhile installing and is there and threads that you could point me too for information on how to build. I have built a pre-amp before but not sure about an Opamp.

Sorry for all the questions. Still hope to other for help with the fine turning is still available.

Crash Pilot1

resonators.doc

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Sounds like you have made a good start Jamie. Have you done any PIC programing ? the PIC you found a Farnell is not available and is not the correct one anyway. You should still be able to source a 16c71 if you need my code but you can write your own code for any PIC with an ADC. Dont worry about the op-amp for now as it will work ok with out it, you can always add it later if you want. The MAX4427 is PN 295036 just make sure it is suitable for your motor, eg what current dose your motor draw ?

Terry

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Terry

I have not done any programming. I am planning on learning how but havn't had the time to teach myself. I have Matlabs 7 and Picbasic Pro but been too busy at work. Hopefully over the next year I can start writing some of my own programs but I'm not capable yet.

I tested the motor cuurent and loaded it draws 30ma . It is only a very small motor with a high torque gearbox.

I will source other avenues to see if I can find a 16c71.

Crash Pilot 1

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Ok Jamie, that is well within limits for the 4427. What you need if you can get it is a window 16c71 so we can adjust the code until your happy with it. Where do you live ?

Terry

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Terry, seems to be easy to put all that stuff together but I have a couple of questions.

Where did you find that motor? Could it work a high torque servo?

Where did you get the rssi signal? I have a 600 mW blackwidowav receiver. Maybe a closer picture will help.

I was thinking on programing the pic with ICPROG, but I don´t know if it works well on Windows XP, maybe I have to go to a Windows 98 SE.

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Where did you find that motor?

It was from ebay, nothing special.

Could it work a high torque servo?

Yes but the code would have to be written for servo use also the patch could not keep rotating in one direction non stop.

Where did you get the rssi signal?

I used the RSSI on on the module.

I have a 600 mW blackwidowav receiver. Maybe a closer picture will help

There are guys here that know the BW gear but not me so I will leave that to the others, Bill maybe ?

Not sure about programing as I only know one way.

How far have you got with the project so far ?

Im close to building a bigger better version myself using a stepper motor but Im not sure if a stepper is the way to go, time will tell.

Terry

Edited by Terry

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How far have you got with the project so far ?

I´m getting all the stuff I´d need together, so I´m at the begining of the project. Think that my pic programer and the ICPROG will do the job well.

I was looking at ebay and see this motor:

http://cgi.ebay.es/17-6-Rpm-Geared-DC-Moto...1QQcmdZViewItem

Do you think it will work well for your project?

Thanks a lot

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These motors are very small, I would look for something a bit bigger. If you get stuck I can sell you a motor, I have a fair collection :rolleyes:

Terry

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Maybe this one. ebay Item number: 130019022225

Terry

Edited by Terry

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