I Want to build a simple tracking device....................

[Torben]

<snipped for brevity>

8 dBm for the transmitter is reasonable and achievable in the size and weight requested.

Unfortunately, I do not have a circuit schematic to offer.

Hi Ron,

Good to have those calculations--I'm going to refer back to this thread when I have a chance to get back into study for my ham licence (I want to wait for a class to start locally so I have some local brains to pick).

So given your conclusion, the 50 miles could be done, but essentially not in a city unless you're on top of the highest building, the bird is higher than you, you already know about where the bird is, and there is no interference?

I don't know very much about this but for me the big sticking points seemed to be the power supply (which you've addressed) and the "in the city" bit, which would seem to make the whole thing quite a bit tougher.

Am I way off or is it not that much of an issue?


Torben

 

[Roff]

Ron, perhaps you could produce higher peak power with a boost converter, at the expense of battery life. Or did you already consider that? Or is it just a dumb idea?

 

[RadioRon]

To address Torben's comments...The power supply only needs to deliver a peak of about 31 mW (9mA) assuming a transmitter efficiency of 20% which is a rough guess for these power levels. If it is pulsed on and off, perhaps it would average out to 15 mW or less. 3.5 volts is plenty for modern ICs to synthesize the carrier and boost it out at 8 dBm since this is a common voltage used in cellphones and other stuff. With a NiMH battery from a small cellphone, we might expect 700 mAH, which translates to about 155 hours of continuous pulsing. That's reasonable for a start. It wouldn't be too tough to reduce the duty cycle and extend the battery life, to some degree.

The "in the city" thing is a tough call, because the shadowing and multipath causes a lot of variation of signal as the bird flies around. But you have the benefit of the human brain listening to the signal, and it is very adaptable to losses of signal and the ups and downs of SNR so it might be frustrating in the city but it might also work some of the time. This also helps to deal with those problems I mentioned of polarization mismatch and the lack of an omnidirectional pattern from the bird. The human being will just have to cope with signal going in and out of the noise floor over time spans of several seconds to tens of seconds. But humans are adaptable, as many of these threads demonstrate.

 

[RadioRon]

Ron, perhaps you could produce higher peak power with a boost converter, at the expense of battery life. Or did you already consider that? Or is it just a dumb idea?

Thats not only possible, but in fact I've been working on one for a project. In this case, yes its possible, but increasing the power output by doing this will increase range but at the cost of battery charge life as you say. As the application I'm working on has much less room for the transmitter than our poster's raptor, I'm learning to keep things simple and so didn't offer the idea for this thread. In fact, there are so many RF ics out there now that are optimized for the 2.8 to 3.5 volt range that it may be optimal to keep the voltage as-is and simply add another amplifier IC to take the 8 dBm up to as high as 20 dBm. No more voltage is needed until you want more than 33 dBm or so.

Just wanted to add that the boost converter idea really shines when you want to keep your battery voltage low, like maybe one NiCad cell for example. Then you have little choice because most of the RF ics that produce power need at least 2 volts.

 

[Torben]

To address Torben's comments...The power supply only needs to deliver a peak of about 31 mW (9mA) assuming a transmitter efficiency of 20% which is a rough guess for these power levels. If it is pulsed on and off, perhaps it would average out to 15 mW or less. 3.5 volts is plenty for modern ICs to synthesize the carrier and boost it out at 8 dBm since this is a common voltage used in cellphones and other stuff. With a NiMH battery from a small cellphone, we might expect 700 mAH, which translates to about 155 hours of continuous pulsing. That's reasonable for a start. It wouldn't be too tough to reduce the duty cycle and extend the battery life, to some degree.

The "in the city" thing is a tough call, because the shadowing and multipath causes a lot of variation of signal as the bird flies around. But you have the benefit of the human brain listening to the signal, and it is very adaptable to losses of signal and the ups and downs of SNR so it might be frustrating in the city but it might also work some of the time. This also helps to deal with those problems I mentioned of polarization mismatch and the lack of an omnidirectional pattern from the bird. The human being will just have to cope with signal going in and out of the noise floor over time spans of several seconds to tens of seconds. But humans are adaptable, as many of these threads demonstrate.

Using the brain as the "hard part" of the circuit. I like that.

So not exactly science fiction then, but even with some assumptions and guesses, also not exactly a slam-dunk.

I found a Pennsylvanian government study where they track birds with satellites and tracking collars on the birds. The collars cost $4000 (US) a pop.


Torben

 

[RadioRon]

I found a Pennsylvanian government study where they track birds with satellites and tracking collars on the birds. The collars cost $4000 (US) a pop.


Torben

Whenever I hear of such prices for hardware that I know costs less than $400 I think "hey we should go into business". But then I think about the several thousand man-hours it will take to build it and divide that cost by the number we will sell and decide that maybe that's not the business I want to be in.

And no, definitely not a slam dunk.

 

[D-cat]

Links to Beacon Transmitters Schematics Site

I know the thread is pretty much dead, but I ran across this page and thought it might be relevant to future surfers.

**broken link removed**

Enjoy!

 

[reny]

how does 4 transistor tracking transmitter work??


https://www.electro-tech-online.com/attachments/tracker2-gif.8136/

 

[Roff]

how does 4 transistor tracking transmitter work??


https://www.electro-tech-online.com/attachments/tracker2-gif.8136/

Q1 and Q2 form a multivibrator that generates very short negative pulses at about a 3Hz rate. Each pulse turns off emitter follower Q3, which briefly turns off the RF oscillator Q4. An FM receiver tuned to the oscillator frequency will emit a "motorboating" sound.

 

[Hypnotize]

How do you measure the distance from the transmitter?
How do I know the location (angle + range) from the receiver?

I want to build a 2D receiver...

Many thanks.

 

[Hypnotize]

Anyone? please... it's super important...

 

[audioguru]

If your FM radio has poor quality and is very cheap then when it moves away from the tracking transmitter the signal becomes weaker.

 

[Nigel Goodwin]

Anyone? please... it's super important...

You have two receivers set a long distance apart, you take a bearing from each and draw the lines on a map.

 

[Hypnotize]

I know the signal gets weaker when the receiver's distance from the transmitter is getting larger. But how do I know exactly where the transmitter is? For example, I want to know the distance in meters...
Another option is for a 4 way monitor - that will tell me forward/backward/left/right i.e., which way to go in order to reach the transmitter. When I reach it (let's say, I'm 0.5 meter from it - the signal will tell me I have reached the transmitter)
The transmitter does not move - it is at standstill at all times.

Thanks!

 

[Nigel Goodwin]

You've been watching too many films - although it's quite possible, with the transmitter sending it's GPS position, and your receiver comparing that position to it's own GPS position.

It's not possible with a simple transmitter and receiver, that's just a imaginary device used in spy films.

 

[blueroomelectronics]

Anyone? please... it's super important...

Really why? School project due?

 

[Sceadwian]

Measuring distance is REALLY tricky, X/Y location isn't so tricky, then you triangulate to find the distance. What you need is a Yagi or other HIGHLY directional antenna, the problem with that is the lower the frequency the bigger antenna needs to be.

 

[blueroomelectronics]

The transmitter does not move - it is at standstill at all times.

Then a GPS with a preset waypoint would do the trick.

 

[Anti-Thief]

Hi Guys! I need a tracking device / or a chip / or anything that can be inserted in any gadgets like cellphone, video cam, laptop, in case you lost it or in case it was stolen a few minutes ago, with a gadget that can be seen the stolen or lost item moving in some direction, its like how the submarine checks it enemies or the jet fighters... is there any gadget like this? please help so I can avoid this thing to happen again... I really need it ASAP pls.. tnx

 

[Anti-Thief]

Hi Nigel! It seems ur very knowledgeable, Can you help me? I need a tracking device / or a chip / or anything that can be inserted in any gadgets like cellphone, video cam, laptop, in case you lost it or in case it was stolen a few minutes ago, with a gadget that can be seen the stolen or lost item moving in some direction, its like how the submarine checks it enemies or the jet fighters... is there any gadget like this? Or any means of retrieving items being stolen or lost? please help so I can avoid this thing to happen again... I really need it ASAP pls.. tnx