SparkFun Forums

[Mikaelr]

I am looking for a small gps unit that I can attach to an arrow for hunting. Can someone please help me with the gps unit and software?

[Mee_n_Mac]

I can't imagine a GPS and battery light enough to not hugely affect an arrows flight. Moreover suppose you could find such a pair. Now you have an arrow that "knows" where it is. Unless you add some sort of transmitter, you won't know where it is. And if you do find the arrow, wouldn't it be easier for you to carry a GPS to note it's position ?

If you want to record the arrows flight path, then you'll also need a datalogger and perhaps a very very fast GPS.

Perhaps you should explain what you're trying to accomplish.

[Ross Robotics]

lol, I agree. If you need a GPS because you keep losing arrows, then you need to spend that money on lessons. If you know which way you are shooting, then you know which way to go to look for it..

[Mikaelr]

The reason for using it is actually to track where the wounded prey goes. About half of all deer that get struck by an arrow are never found. This would be a humane way to make sure that doesn't happen.

Hopefully that helps with the reasoning. We found a vendor that can provide everything for a prototype but it was for almost $1000. I was hoping to find something more affordable. Any thoughts?

[Mee_n_Mac]

Do you really need a GPS for that purpose ? Here's a counter suggestion ... all you need is a simple radio transmitter (you'll need a more complicated one to relay the GPS position to you). A simple RF beacon will be smaller and less weight than a GPS, battery, MCU and radio. You then use a directional antenna to find the game, as is done w/a lot of animal tracking. It won't be as easy or as quick as it would be if you had lat & long of the game but it'll also be less $$. Frankly I'm surprised it could be done acceptably for $1000.

How big and how much weight is the $1000 unit ? Maybe I'm being overly conservative in my opinion of how small and light such a unit needs to be.

[Mee_n_Mac]

For comparison here are a bunch of kiddie trackers that perform much the same function. Note their size and weight. Also note that they all (I think) use a cell phone to call in their position. Would requiring a cell phone place too much of a limit on use of one in an arrow ? In some places it certainly would.
http://gps-tracker-review.toptenreviews.com/

[Mikaelr]

I did look into rf receivers but they said it could only be tracked for a few feet. Could you help me find an alternative?

The gps unit we found is what was being used on bats for tracking. We just need something that can attach to the back of the arrow.

[skimask]

Any thoughts?

Buy a rifle.

[lyndon]

The problem with a directional tracker is that it's hard to travel in a straight line in the woods. I'm with 'Mac on this. $1,000 sounds too good to be true. Is that just parts or does include development?

[Mee_n_Mac]

These people seem to have a variety of small systems for tracking animals. Their GPS systems are small and light, though I don't think they relay position back to a receiver w/o some other optional equipment.
http://www.lotek.com/avian.htm

No matter how I think of it I can't find a fool proof solution. Let's say you could package a GPS small and light enough to fit in/on an arrow and not drastically affect it's accuracy and range. In order to find the game it needs to transmit it's location. That means an uplink to a cell phone tower or some other radio link. Depending on where you hunt, it can be quite easy to be out of reach for the former. And that type of radio equipment is larger, heavier and more $$ than a simple RF link or beacon. Additionally GPS signal strength is easily degraded in heavy woods and that's with the antenna pointed up. What happens if the game lands on top of the arrow and GPS ?

So if a GPS isn't a good answer, then perhaps a simple RF beacon would be. The hunter then carries a Yagi type antenna to listen to where the "beeps" are the strongest. The good thing is that even if the game isn't found, the arrow plus electronics is cheap, some tens of $$s, so losing them isn't the $$$ penalty that losing a GPS arrow would be. The problem is that the RF will be line-of-sight and that means it may be blocked by trees and hills and valleys. Plus toting around a receiver and Yagi will be a (minor) PITA. It makes me wonder if a small quadcopter "drone", equipped w/the receiver wouldn't be less of a PITA and more effective in finding the beacon ? It wouldn't be hard to make it semi-autonomous; have it do a search pattern and hover over the target (if found). But a good quadcopter and receiver would likely be $600 - $1000.

Perhaps a better solution would be to have the arrow "puff out" some markers or marking paint at fixed intervals, to better aid in tracking the trail ?

Or some other "odd" solution. I don't know. Coming up with a semi-foolproof answer that's light and small enough, let alone cheap enough, is not an easy task.

[Mikaelr]

Thanks for the analysis, Mac. I do appreciate it. If rf is line of sight only, that won't work since there will definitely be trees in the way as the animal leaves the original area. I think a device puffing out markers would take more room than a gps.

@lyndon, it does include the gps device and the tracking device so no dev necessary besides us adapting it for fitting on the arrow.

It sounds like it may be a better deal than I thought. Thanks for your responses! Let me know if there is anything else you think I can look at.