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Author Topic: wildlife radio collar reciever  (Read 1313 times)
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I'm a wildlife biologist hoping to build an automated radio receiver for tracking radio collared small mammals (mice, chipmunks etc...)

The frequencies I would like to recieve are 148-151 mhz. which is one of the the generally used wildlife tracking frequency bands. Note that this is very close to the 2 Meter ham radio band (which is 144-148mhz), so if there any hams out there with advice, chime in.

What I would like to make is a system that would monitor a set of designated frequencies (corresponding to deployed radio collars), and record the signal strength of each pulse received. It would have to monitor each frequency for a few seconds, before switching to the next frequency on the list. When it records a pulse, it would send the signal strength and a timestamp to a CF card. The whole thing would have to be remotely powered, probably on a 12v system.

So, my question is, is there an Arduino compatible radio receiver board that works in those ranges? Something that works with standard coaxial antenna sockets? I've seen lots of receiver boards that work on AM-FM, Wi-fi, bluetooth, 800mhz and other frequencies, but none that can tune to the standard wildlife tracking frequencies.

Any advice is welcome.
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You could consider designing a shield that would receive in those ranges.
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record the signal strength of each pulse received.


That's what's a little difficult.  

There are some pretty low-cost 2M handhelds on Ebay etc. But you'd need to find a schematic and a way to get at some RSSI (Received Signal Strength Indicator) point in the receiver.

I suggest you ask over at: https://groups.google.com/forum/?fromgroups#!forum/rec.ham-radio  and hopefully you'll find someone interested in working with you.  I would if I had ANY spare time... sorry!

Tell us more about the transmitters you are working with...
« Last Edit: April 25, 2013, 10:43:47 am by terryking228 » Logged

Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
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The transmitters are very simple, Crystal controlled two-stage design, pulsed by a multivibrator. It basically just sends a short pulse at regular intervals.  every pulse is the same frequency and the same strength (until the battery starts dying). So by measuring signal strength, we can tell if the collar is moving, or stationary, because as the distance between the collar and the receiver changes, and the orientation of the collar antenna changes, the apparent signal strength will change.

The transmitters I use on mice are about the size of a jellybean, weighing about 1 gram, including the battery. The entire transmitter is sealed in a glob of epoxy, with a short antenna sticking out. They have a reed switch, which allows them to be turned on and off by attaching or removing an external magnet. The battery usually lasts about a month. Once the battery dies they have to be sent back to the manufacturer to be refurbished.

http://www.holohil.com/bd2c.htm

Yes I was wondering if hacking an off the shelf receiver would work best. But I was hoping that there was some existing way to do it, just a simple programmable radio receiver that outputs an analog or digital signal that an Arduino could work with. It seems like almost any receiver should be able to be adapted as a sensor, which would provide an analog input or digital input to the Arduino. It's really just a matter of measuring the maximum amplitude within a time interval. There seems to be a board or sensor for almost everything, I thought there might be an existing 2 meter option. it would certainly be easier if I could use something already available.

I might have to head on over to that ham radio page.

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Tom Igoe did an interesting monkey tracking project in Ecuador a few years back.
http://www.tigoe.net/blog/category/physicalcomputing/266/
Maybe you can get some ideas from his project.  In any case, it is an interesting read.
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GNU Radio coupled with a ~$25 software radio (DVB-T radios) will cover the frequency spectrum you're after...but that's about the limit of my knowledge of radio-anything.

http://gnuradio.org/
http://superkuh.com/rtlsdr.html
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Those are some cool devices. What do they cost? What sort of arthropod is
large enough to carry a transmitter? Roaches?

Since this is all so specialized, I should imagine you're best off hacking an existing
receiver that's matched to the transmitter. Where are the receiver links?
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64MHz to 1,700MHz Software Defined Radio

http://www.funcubedongle.com/

drop a line to its support to confirm if it works. I know it will not work with Arduino but at least it works with Raspberry Pi.
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The "Transmitters he is talking about are crystals at submultiples of the desired frequency with a high Q tank coil resonant at the desired transmitter frequency.. Some of them use a variable frequency multivibrator for reporting temperature and some are fixed frequency multivibrators, They are simple to make and an Arduino could report quite a lot be essentially OOK'ing this audio frequency square wave signal that is used to excite the crystal and the frequency as well as the rate at which it is interrupted can convey information... It would be a very simple task to write something for a Tiny 85... The real trick as I remember is terminating the crystal for best output. I made something similar in the 70's with those murata helical resonators and a 556 and a crystal (usually @ 12 MHz as the 12th harmonic is 144 MHz @ the edge of the band and frequently used with low power devices like this for "Fox" hunts or "T" hunts ) where the transmitter/beacon is carefully hidden, I buried one and wrapped the antenna in a weed that honorably gave it's life for the cause... Besides I Had to give them a clue.. A wilted weed...   Long time ago.

Doc
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Yeah, they are pretty cool devices, also fairly expensive. About $100 each, and about half that to refurbish with a new battery. I'm sure I could probably build them myself for a small fraction of the cost, so that's another possible DIY (or DIM=DoItMyself ?) project.

I like the Rapsberry Pi idea, but I wonder what the power consumption would be.
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Model B owners using networking and high-current USB peripherals will require a supply which can source 700mA (many phone chargers meet this requirement). Model A owners with powered USB devices will be able to get away with a much lower current capacity (300mA feels like a reasonable safety margin).

from 5V/300mA to  5V/700mA and depend how much funcubedongle eat.


http://www.raspberrypi.org/archives/260
« Last Edit: April 27, 2013, 01:56:20 pm by sonnyyu » Logged

the land of sun+snow
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Looking at the transmitters, they have just a few dollars worth of parts. Changing
the battery can't be any harder than on a wristwatch. From what doc.e said, he
could probably suggest how to build your own receivers too. He knows all about
2m [150 Mhz] RF.

I should think it would be much easier to use Arduino than r.Pi.
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Why change battery?

Researchers Develop a Penny-Sized Nuclear Battery

University of Missouri

still in R/D stage, to use it need wait.

Now biggest problem is the battery last 20 years but mice live approximately one and a half years, sometimes even three years.

No more recycle transmitter, recycle mice is needed.  smiley-cool




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Changing the battery is difficult because it is completely sealed in a glob of epoxy resin. You can't just open a battery compartment. I'm honestly not sure how they do it, maybe they dissolve the resin away, or carefully crack it open, or saw it apart with a dremel?
There are schematics available for the transmitters. so I could probably do that (or have a student do it for me smiley-cool )
http://jeb.biologists.org/content/208/21/4063.full

Based on my research, the "half life" for a deer mouse in the wild is about 30 days. It's a cruel world out there when you're at the bottom of the food chain.

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Dissolve epoxy resin might be day to day job for people do reverse engineering.

There are off-the-shelf  epoxy resin dissolver solvent available;-

"Attack" Epoxy Resin and Adhesive Dissolver Solvent Remover & Cleaner

www.esslinger.com, $12.95

Safe for use on metal, stones, glass, and wood

The plastic is missing here, since solvent might be very aggressive to most types of plastic.

I guess either holohil.com replace new case or use customer solvent which safe for case.

Your university has chemical department?  It should be a piece of cake jobs to make customer solvent.




« Last Edit: April 27, 2013, 05:52:20 pm by sonnyyu » Logged

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