radio tracking

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Well-Known Member
Jul 2, 2002
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hi guys
what options are there radio tracking units for rockets?
i know of GPSflight and rocket hunter, i also know about watson, but i don't know pricing or anything like that about the watson unit. are there any other units out there for tracking rockets??
if anyone has a used unit they want to sell please email me as i am interested in buying one

Programming By Pete, homebrew radio tracking transmitters for the 2m and 70cm amateur radio bands

Ramsley Electronics MR-6 Model Rocket Tracking Transmitter Kit, tracking transmitter for the 2m amateur radio band, requires that you figure out some other way to have the radio send your callsign every once in a while.

I'm building a simple-ish system using the Ramsey transmitter and a Parallax BASIC Stamp I microcontroller. The microcontroller's job is to send a string of morse code:

...- . --... .-. -.- - --.- - --. ___________ ____________
VE7RKT QTG (10sec dash) (10sec dash)

VE7RKT is my radio callsign, QTG is a short code that means "I will now send two ten second long dashes." I think originally it was meant to help the guy recieving tune his radio properly, but for my purposes it'll give a good steady signal to home in on.

The whole thing will fit in a 24mm tube, with a wire antenna running up the parachute shock cord. I should still get a weak signal before deployment, but after deployment I should get a nice strong signal. By using a handheld reciever with a directional antenna, you can trace the transmitter's location (and assuming it stays attached to the rocket, you'll find it too).

I have seen people use little wildlife tracking transmitters to good effect, but they're not cheap; might be because they're self contained all weather high impact units with three months of battery life. ;) I'm expecting to build my system for about half the cost. Which is nice, because I'm expecting that some day, I'm going to lose one to deployment failure (I've seen that happen... bip! bip! bip! bip! bip! bi-- "Well, it's on the ground now.")
Don't forget that the RDAS from Aerocon has a add-on GPS module that would be another consideration.

We could always get a small radar set for tracking. Of course cardboard and plastic dont reflect radar well so we need to make rockets from aluminium or other light metal, the average rocket is also too small to make a good target sowe need to make it bigger.

Hey what happened to my model, anyone want a lift into orbit?:D

I dont think you can beat the mark ! eyeball. You will lose the odd rocket but not too many if there are enough people spotting chutes.

There is always the "fakir rocket", you know the one that reaches apogee and disapears just like the rope trick.

Justy: that unit looks good , but the thing is its only got a 1/2km range which isn't very usefully for hpr.
i have looked at the RDAS but that would involved buying a whole new altimeter ...etc
looks like its Rocket hunter or GPSS flight for me,i have quite decided

Depends on how you use it. Its range when it's up in the air will be a LOT better than 1/2mi, so that acts as a backup method for getting an initial track. Plus, think of the directional antenna on the reciever as a telescope for radio. Once it's on the ground, it might not have quite as great a range, but you know roughly which direction it's in (you -do- watch your rocket fly, right? Or if you lose sight, start tracking while it's still in the air and still shouting over the terrain), so you walk that way until and you can get within radio range of the rocket again easily enough. So a 1/2 mile range would be acceptable.

The first link I gave you, the guy built a rocket tracker using the same transmitter I'm using. He used a homebuilt microcontroller to send the morse code, but otherwise it's pretty much exactly what I'm building. He says he got a range of two miles on the GROUND. If the wind is strong enough to carry my rockets so far downrange that a combination of initial in-air sighting and a four mile wide search swath on the ground isn't enough to find it, it's too windy to fly. :)

$50 for the radio kit, $5 for the old style BASIC Stamp (bargain bin sale!), some wire for the antenna, a speaker if I want the Stamp to drive an audible beeper too... and my first version suitable for 38mm airframes will be complete. Replacing the Stamp with a newer, smaller version will let it fit in a 24mm airframe, which is good, because I have an HPR project with a 24mm minimum diameter sustainer that WILL need radio tracking.

Now if you can spend the money and get an RDAS with GPS, that's even cooler. You have a laptop at the launch site, and you're constantly recieving position updates. When the rocket stops moving, you read the GPS coodrinates, pick up your handheld GPS reciever, and you walk until your coodinates match the ones on your laptop. Poof, you're standing within 10 meters of your rocket. Don't step on it. :D
I designed a circuit that emits a 1/2 watt FM, audio and visual signal and only uses about 25 parts. It transmits at the end of the FM band so I can easily pick it up from several miles away with a Ramsey Fox Hound. Ramsey kits are expensive and very challenging to assemble and get to work. I suggest buying their preassembled kits especially their rocket tracking transmitter. Surface mount components are a pain to work with! I have built several Ramsey Kits and I don't think they're worth the time and effort.

Bruce S. Levison, NAR #69055
I've tried the RDAS GPS without much luck.

I built my own GPS tracking system using a 440cm transmitter with a TinyTrak APRS packet modem and a Garmin GPS. I have a Kenwood D7 connected to a Garmin GPS on the ground and it gives me a distance and bearing to the rocket. I also get altitude and position updates as the rocket is coming down. A lot of people have really enjoyed me reading off the altitudes during the flight.

You can see a small pic on my website:

There is a little more detail in my L3 documentation at:

Be warned, it's a little big.
The issue with the Ramsey Transmitter is the freq that it transmits on, 146.5mhz. This is the 2 meter band which means that the wavelenghts are 2 meters wide, to build a yagi to pick it up the elements are half wavelength. The reflector is 42 inches and the driven element is 37 inches making this an unwieldy beast.

Adepts tracker is in the 70cm band and the yagi is much more managable at around 13 inchs for the elements. The wildlife management trackers are in this range as well.

I am going to try the Ramsey transmitter even knowing the issues of the antenna, I have found, many many, plans online for a flexible 2 meter yagi built from PVC pipe and tapemeasure tape for the elements.

I will post my findings later I amost have everything together.

A member in our club is using the Garmen GPS units, which I cannot afford. The issue with the Garmen is that it only sends it info back to the other unit when the mike is keyed so he has designed and build a device that keys the mike at a set time 30 secs. This devices just plugs into the external mic jack so it does not effect the warrenty on the radio. He is able to get a good bearing on the rocket as it goes over the hill and out of range.

My Ramsey transmitter kit arrived yesterday, and I wish now that I'd listened to Teflon... DANG, those things are tiny. I knew SMT bits were small, but I didn't think they were THAT small. Not quite sure how I'm going to make it through this project. The good news is, there aren't that many components, just 30 or so.
Err... I put 440cm, it should have been 440 mHz or 70 cm. In either case the higher frequency keeps the antenna sizes down compared to the 143.9 normal APRS frequency.
I'm also building my own radio tracking. I'm using a set of Uniden Walkie Talkie radios. They say they have a 3 mile range - should be enough if tracking in the open air. The only thing I need to do now is build a directional antenna. Anyone have any good sites or info on how to build one? The antenna now is omni-directional which isn't too good when trying to find a rocket :)

Well, it doesn't have a plug in for an antenna. The model is the Uniden GMR325-2. I have just taken the case off to look at the setup so far and it has a coiled copper wire soldered to the board for an antenna. I have also added a circuit that triggers the call button (this emits a warbling tone that lasts about 5 seconds) every 7 seconds or so. That way it always is broadcasting.
Here is the link

They also come with a belt clip that I know I can mount to the airframe, then just clip the radio into that for a sturdy mount.

Any ideas for a better directional antenna.

In that drawing, the extra antenna is plugged into the HEADPHONE jack, not an external antenna jack. The only reason it uses the headphone jack is because it's a convenient place to tie into the electrical ground. You could solder it to the ground of a microphone jack, or the negative terminal on the radio's battery, or the metal casing if it has one, for the same effect.

I asked a guy in the radio club if there was a way to make a decent yagi for the 2m band, but smaller... and he suggested using a yagi for the 70cm band. If you're just recieving, he said, performance shouldn't suffer much, and it'll be much easier to handle. But DO NOT TRANSMIT... you'll let the smoke out of the radio.
Just got back from testing the transmitter. So far this is the Transmitter Unit
1 Uniden GMR325-2 Unit - 22 channels
1 Red Blinking LED
1 AAA Battery in holder

This unit has a cool call function. When you press call it emits a 5 second warbling tone then turns off. I realized this works by closing a set of contacts. In my experimenting my first version used a reed relay to close those contacts. By accident my blinking LED came into contact with my two wires I soldered onto the Call button contacts and started to blink. Hmmm....very interesting. I noted polarity and soldered them there. No luck getting it to transmit - too much voltage was used in making the LED blink. So I put a 1.5v AAA battery in series. Blamo! It worked. The LED blinked and activated the call function every 5 seconds, providing a continious output! This means all I had to add to the circuit was an LED and a AAA battery. Not a whole lot there, and it will still mount nicely. I'm thinking of making a plug module that I can just plug the unit with the battery/LED onto the end of a connector for ease. Tomorrow I'm going golfing and am going to put the transmitter into my car and check the status out on the course :D Then if it works okay I'll start on the directional antenna.

The unit will fit into a 2.56 body tube, so it is by no means small, but I'm planning on putting it in a 75mm min diameter rocket. I would say batteries and everything you have 6 ounces worth of weight. Not bad for something I threw together. I so far have spend $20 for the radios and $2 for the LED. Once I get the antenna's done I will see a total, but I'm guessing it will be about $40 total. When I get the antenna done I'm going to do some hide and seek with it in an open field to see how well it's working.


Thanks for the info. So basically I can take the connection point of the antenna now (a coiled copper wire) and replace that with a connection point to two antennas that are the same length but go in opposite directions? If so that wouldn't be that hard to do. These radios transmit from 462.5500 MHz to 467.7125 MHz, so would a 70cm Yagi work? I know the wavelengths range from 64.8cm to 64.1cm, is this close enough to a 70 cm Yagi. Anyone make a 65 cm Yagi?

I saw a tutorial from a rocket guy that built his own 70cm Yagi out of 1/2x1/2 wood and 1/8" brass rod. He had a BNC? connector. Where would that fit on an outfit like this?

Regarding Magic smoke, I have a bottle here that I can sell you to fill up those electronic gadgets that you have inadvertently let the smoke out of... :D

You can replace the antenna with one length of stiff wire or rod -- for best results, a length that is 1, 1/2 or 1/4 wavelength -- and another stiff wire or rod of equal length connected to electrical ground going out the other side.

Note that this is a kind-of-directional antenna. It tells you that the transmitter is lying on a line perpendicular to the antennas. That means the transmitter is could be either in front of you, or behind you. With a rocket, that's hopefully not much of a problem, because you ought to have seen which way the thing went.

If you want to make your own yagi, google for "yagi calculator" or something, and you'll hit a few sites that will give you plans for building one and calculate measurements based on a frequency you type in.

But all this is hypothetical, because...
From the FCC website
95.194 (FRS Rule 4) Types of communications.

(b) You must not make, or have made, any internal modification to an FRS unit. Any internal modification cancels the FCC certification and voids your authority to operate the unit in the FRS.

(c) You may not attach any antenna, power amplifier, or other apparatus to an FRS unit that has not been FCC certified as part of that FRS unit. There are no exceptions to this rule and attaching any such apparatus to a FRS unit cancels the FCC certification and voids everyone's authority to operate the unit in the FRS.

So while people here may be telling you how you might modify these radios, we are certainly not encouraging you to do so... this is for "educational purposes only". I'm encouraging you to get your amateur license and pick up a dual band VHF/UHF handheld, swing through a swap meet for a good 70cm yagi, and rig up a tiny morse code beacon to a transmitter. Clear? Good. ;)
About that BNC connector on the yagi plans, you'd pick up a matching connector and using coax cable, connect the center pin to the antenna and the sheath to the electrical ground. You don't have to use BNC connectors, it's just common because that's the connector on most handheld transcievers. You can use any connector you want, really, or no connector at all... just solder the coax cable into place.

Coax cable for radio is not the same stuff as coax cable for television. Find a radio shop, tell them what you want to do, and they'll find the right cable for you.
Yagi antenna's are pretty easy to build and they are very directional but they have to be designed for the specific freq. that you want to receive. Sounds like the site that you may have some very good information on building yagi's.

Here are a few that I found interesting.

All of these are good sites and you can get the basic of design and building tips for yagi's. Very easy to create and use, I am building two of them right now. One of the tape measure yagi's for my Ramsey transmitter and then I will be building one in the 70cm range when I decide on which transmitter I will be useing in that range.

I am interested in the Uniden radio design that you have. Do you have any pictures?

No pictures yet. Today I tested out the design with the Uniden stock antenna (remember all hypothetical stuff here ;) ) I could get about 1 mile away (this is in Denver, Colorado, with buildings, trees, hills, etc) before losing the signal. I went and got two antenna's that I can adjust to the wavelength and I am going to arrange them in the manner that Bruce posted. I will probably finish up that work tonight. Right now I have a radio with a AA battery holder and blinking LED attached to that on the case of the radio.