Trackers & how to use them, that dark mystical art revealed!

Handeman said:

Here we seldom fly about 10K but that could mean landing over a 1/2 mile away. While you have open playa, we have corn fields, creek bottoms, woods, ponds, prairie grasses, and bogs, all in the first 1/4 mile. The distances and altitude may be much less, but the ground cover can hide a rocket very very well. Land marks are trees, corn rows, off colored bushes, fences, and if you are lucky, something tall and different just beyond where the rocket landed.

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For ground cover, parachute color can make a huge difference. Greens and yellows are horrible, as they just blend into the crops. Dark blues and blacks while hide well, too.

Bright neon orange and bright neon pink are your friend -- a small bit of it visible in between leaves stands out really nicely.

-Kevin

troj said:

For ground cover, parachute color can make a huge difference. Greens and yellows are horrible, as they just blend into the crops. Dark blues and blacks while hide well, too.

Bright neon orange and bright neon pink are your friend -- a small bit of it visible in between leaves stands out really nicely.

-Kevin

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The cheap orange streamer material you get at Home Cheapo to tie to the extension ladder hanging out of the back of your truck
is fantastic for just that reason.... Super light and thin ( because it's cheap... lol ) it won't interfere with your recovery no matter where you tie it..
Could be a top loop at the tip of the chute,, or right onto the harness... A nice long length will lay out a long way on the ground or in the crops...

Teddy

Just for anyone who didn't see this yet, I wrote an article recently on commercially available GPS trackers.

For the remark about the age of the PDF article, really there hasn't been much change in radio direction finding for years. But there is a majorly ignored area in rocketry. If you have a BRB transmitter (or other fm transmitter/won't work with Walston), you can also make use of a TDO unit. They generally consist of two antennas and circuit to switch between them at an audio frequency. Then when one antenna is closer to the transmitter than the other, you will hear the switching tone. When they are broadside to the source, you don't hear the tone.

With one of these units, you can pretty much walk right up to the transmitter without having to attenuate the signal at powers typically used for rockets. The units are used in international rdf competitions where people are timed to find five transmitters each transmitting in turn on the same frequency. Quickest person to find all five and return to the start point wins.


Kirk

If you have a BRB transmitter (or other fm transmitter/won't work with Walston), you can also make use of a TDO unit. They generally consist of two antennas and circuit to switch between them at an audio frequency. Then when one antenna is closer to the transmitter than the other, you will hear the switching tone. When they are broadside to the source, you don't hear the tone

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Kirk - Do you have more info on TDO units? I searched but could not come up with info or pictures.


Chris

resurrecting an older thread... I think this link might be a good starting place for TDOA units... https://theleggios.net/wb2hol/projects/rdf/tdoa1.htm
I just found it myself after seeing the term on this thread and searching "Teh Googles"

I had "issues" with my dry run using a BRB and a Yagi last weekend, so I'm looking for what I can do to improve my foxhunting skills. When you think about it, rocket tracking is a lot like rdf "foxhunting" only you hide the transmitter from yourself.

rbelknap- what issues did you have? I'd guess you had problems getting close?

I have been doing a lot of tracking lately with the MARS club and have developed some new ideas on technique that I have found to be very useful. I am a firm believer in the use of an offset attenuator, the one made by arrow antennas to be specific, to get close and to make the "where to walk" decision easier. I have only ever used a yagi (7 element arrow antenna, or a 6 element home brew from brass rod) and the attenuator plus radio. I don't have experience with the higher tech stuff, nor with comspec or walston.

N

Yep. Rocket landed probably about a mile a way. (2 fields over and behind a tree/brush line. We had clearance from all the land owners in the area so access was no issue.) I really didn't need the beacon to find it. But that was the point of the dry run; to get some experience with it before I absolutely need the beacon to find the rocket.

The transmitter was at high enough power that even with the yagi pointed 180° away from where I knew the rocket to have flown, I was basically getting a full signal. (the S-meter on the UV-5R is useless. I knew that going in.) An offset attenuator would probably be a big help, as would a radio with a working s-meter. So would more practice and an RDF Elmer. Not to mention getting people to "leave the guy holding the yagi alone" Hard to do that last one at a scout launch with a bunch of kids and their parents interested in what I was trying. We announced it as a demo launch and explained the rocket had a radio beacon for location tracking on board.

I have a 3 element arrow yagi. (It's what I could afford at the time I got the BRB, and also what our onsite vendor had stocked.) I might try building an attenuator and/or a TDOA box, to see how those work. I might also upgrade to a 5 or 7 element yagi at some point.

At 180 degrees you are getting the back course. Every RDF will pick up a strong signal 180 and 360 out. The antenna knows its in line with the signal but doesn't know if its pointing at the signal or away.


Because I am addicted, this is coming from my phone.

The most important factor in using any tracking system is to ACTUALLY USE THE DANG THING!!!
Don’t get lazy because you think the rocket won’t go so high as to lose it. Thinking like that WILL, WILL, Will result in a lost rocket/s.
Consider this the “Gospel of Eldon”.

Personally I use a Walston system and I have never lost a rocket when using it.

Forgive me if I'm repeating much good material already shared here.

Even a 3 element yagi should have a pretty good front to back ratio, but as others have noted, if you're close, and/or the signal is very strong, then you may not see much (or any) difference. Attenuation is a great way to "expand the scale" and make use of the dynamic range of your signal strength meter, or even detection by ear. You've got to reduce the signal enough so that it's very small when not pointing at the transmitter, allowing you to actually see the difference as you point it in the right direction.

If you're interested in an alternative to the Arrow offset attenuator, I've been using the K0OV offset attenuator kits for amateur radio fox hunting for years. If you're okay doing a bit of the construction yourself, these work well.

I know that some here will say that signal strength meters aren't all that important, but I disagree - it's an important component of effective direction finding, and you're missing out if your radio doesn't have one.

Another point about a beacon like the BRB: if you're swinging your beam antenna around, trying to get a bearing on the signal, but the transmission is short, then you've just barely got any direction information before the signal's gone. One of the great things about the BRB is that it's programmable, and you can change the duty cycle (on vs off timing). Sure, the longer the transmission, the shorter the battery life, but I've found a compromise that provides a longer transmission that's easier to DF, and still maintain a battery charge life that's many hours long.

This stuff may not matter for those who are flying in an environment that allows seeing the rocket on the ground before getting really close, but if it's in tall grass, crops, trees, etc., you could be almost on top of it and not see it - and that makes these DF tools like signal strength meters and attenuators much more valuable.

Mark

rbelknap said:

Yep. Rocket landed probably about a mile a way. (2 fields over and behind a tree/brush line. We had clearance from all the land owners in the area so access was no issue.) I really didn't need the beacon to find it. But that was the point of the dry run; to get some experience with it before I absolutely need the beacon to find the rocket.

The transmitter was at high enough power that even with the yagi pointed 180° away from where I knew the rocket to have flown, I was basically getting a full signal. (the S-meter on the UV-5R is useless. I knew that going in.) An offset attenuator would probably be a big help, as would a radio with a working s-meter. So would more practice and an RDF Elmer. Not to mention getting people to "leave the guy holding the yagi alone" Hard to do that last one at a scout launch with a bunch of kids and their parents interested in what I was trying. We announced it as a demo launch and explained the rocket had a radio beacon for location tracking on board.

I have a 3 element arrow yagi. (It's what I could afford at the time I got the BRB, and also what our onsite vendor had stocked.) I might try building an attenuator and/or a TDOA box, to see how those work. I might also upgrade to a 5 or 7 element yagi at some point.

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I use the BRB/Ham radio approach. For the equipment I have, tracking would be pretty much impossible without both an attenuator and a working signal strength meter. The attenuator is required when the rocket is in the air and when you're getting closer to the rocket on the ground. However, the attenuator (the Arrow one anyway) attenuates the signal even when it is turned off. So, if you're hunting for a signal you don't have, it saves time to bypass the attenuator. For me, the audible radio signal isn't very helpful (unlike other tracking systems where the sound volume is easy to use). Thus, I use the attenuator to get the maximum signal on scale.

Jim

When you get right on top of rocket in tall growth [corn, soy beans, prarie grass, woods...etc] 100ft or less. Remove the antenna and point the receiver naked.... it will get you there.

If no signal re-attach antenna and move into a closer circle.....remove antenna [or co-ax] and repeat search with receiver until you find it.


This has worked for me with Com-Spec & Walston. I even found a tracker [tranmitter] with antenna missing after a CATO.

I cannot over emphasize the need to practice use before the first flight or at least go on the hunt with a mentor a few times.

Simply attaching transmitter at eye level [to learn, increases success rate before on the ground or handing in tree, which has it's own set of screwy rules]
to tree, pole ,etc. drive 1/2 mile away check signal.....then mile etc... till ya figure out your range.

Even better let someone hide it 1/2 mile or more distance, then go find it. This will give you real experience & increase success rate.


If I have a signal..... I WILL find that rocket. It may take 6-7hrs.... but I have found every rocket that ever had signal......mostly others who gave up.

There are so many scenario's that must be learned to be effective at hunting it will take dozens of hunts to experience them all. [ well we never experience ALL of them, there's always the crazy one waiting.]

For some ham stuff:

Here's an offset attenuator one can mount in a leetle box with a 9Volt battery on the antenna if they wish:

https://www.west.net/~marvin/k0ov.htm

His webpage: https://www.west.net/~marvin/

Cute $75.00 50mW 2m tracker:

https://www.west.net/~marvin/microhnt.htm

With this offset attenuator, it's best to practice with it first. One can cut back the gain with the dial as they get closer to maintain directivity. Kurt

rbelknap said:

... So would more practice and an RDF Elmer....

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+1 on this !!

For those who don't speak "Ham", an "Elmer" is a mentor. Someone with experience, who can give a new user a little guidance.

I have only used a tracker a few times, and I would not have been successful without a little help from Woosh club prez Mark Hackler. Mark gave me a few tips that made tracking easier.