Tracking transmitter, small but grunty

[Gaskell]

OK now first off I know these circuits are all over the net and this forum BUT I'm after a small sized circuit with REALLY good range (I know thats like askin for a cheap to run V12 dodge viper!). The most important thing is the range here, Like 100 metres isn't gonna cut the mustard here and most of these circuits have a range of less than 100 metres. I did find what I'm after (better than I hoped for) but it was about $2200 US.

Ok so a little more specific here for you guys.
Range hoped for: about 1Km would be sweet
Size: naturally dependant on range and battery size but no bigger than about coffee cup sized
Output: just a beep or click maybe at 1 second intervals (longer wait between beeps/clicks should improve battery life.

So heres the nice little challenge for whoever can step up here. I'm open to different types (does not have to be restricted to FM signal).

A big THANKYOU to whoever can help with this.

 

[stevez]

A small handheld amateur transceiver can be had in that size. You must be licensed to use it and there must be proper control. The tranceiver I describe can be had new for about $150 US. A second small receiver could be use for control. If you do go the amateur radio route and are licensed you'll realize that you'll need to operate within those guidelines. In the US that means the transmitter must be "in control" - that control can be remote (via radio) but it must be controllable and monitored by someone. That which is transmitted cannot be for commercial use - strictly personal/hobby.

 

[stevez]

An afterthought - you and other members are likely to get more useful advice if you'd indicate your location.

 

[Gaskell]

I'm thinking more along the lines of a dog tracking collar or similar, just sends outs beeps or clicks to locate. It would need to be small enough to not be and issue either weight or size wise but with a good range.

BTW I'm in NZ, I'll update my profile now.

 

[Sceadwian]

The problem is anything that has a range like that is going to be transmitting at illegal power levels. As it's just a tracker signal simple AM bursts is probably the simplest method. Perhaps a shielded spark gap type transmitter using a capacitor and inductor to chose the oscilating frequency. You can't get much simpler than that.

 

[Gaskell]

hmmm, yea I'm unsure of the law in NZ when it comes to that but I know a mate has tracking collars on his hunting dogs with a range of about 2Km, the collars cost him a packet. He's in a wheelchair so keeping up with his hunting dogs is out of the question and sometimes they can chase stuff for miles. So he tracks them with the collars (the reciever unit came with 2 collars and is specifically for them). I think for what I'm after 1Km would be plenty.

A couple of questions:
What is the legal limit on transmitting power levels?
Is there going to be a difference in range (for a above level) between FM, AM or GPS?

Hmmm, this seems to be a bit harder and complicated than I thought. I definetly don't want to break any laws or interfere with anything (like radio stations) that could cause problems to anyone. I'll see what info I can find in NZ law for transmission power levels.

 

[Sceadwian]

The point is your mate bought those devices, that makes them legal, they used aproved frequenies and power output levels, and were likley tested by a local regulating commision, even makeing a home made device that does the exact same thing as that is going to be technically illegal unless you have an amateur radio license. You would however have to check NZ law as you said.

 

[Gaskell]

I found this **broken link removed** about power levels, frequencies etc. According to this I can use certain frequencies at certain levels without a licence. Can I get the range I require within these limits?

BTW I'm sure I posted this message yesterday but it seems to have vanished.

 

[Sceadwian]

The 26.95-27.3 or 40.66-40.7MHZ band seems like the best bet. They're low frequency so it's easier to build a circuit that uses those frequencies. Those could actually be generated directly with a crystal oscilator without a lot of complexity and they allow 1 watt max, which should get you a few km's line of site and be relativly reliable within 1km with obsticals.

 

[Gaskell]

OK that sounds perfect, now the question. How do I get a diagram and parts list to build the thing? Hopefully someone here can give me a hand in designing the circuit for me. I can just cruise into DSE to get all the components and board to build a working model. If all goes to plan I'll actually get a proper board designed and built, but for the first model I'll just use the some versa strip board.

 

[Nigel Goodwin]

Don't you have little licence free walkie talkies there?, buy a pair of those!.

 

[Shax]

Tracking transmitter...

Have you tried the tx modules from Radiometrix or Laipac?

I use these modules for tracking rockets to altitudes over 20,000 feet, and ground recovery ranges of over 5 miles...

I've attacked a foto of a prototype... This one runs on 433.94mhz, and using a 120 mah, 9.6v nimh stack runs for about 4 days... If I tweak the code in the pic, it'll run considerably longer.

 

[Sceadwian]

Actually tracking the transmitter is a different story unless you want to tack a GPS recevier onto it.

 

[Shax]

Actually tracking the transmitter is a different story unless you want to tack a GPS recevier onto it.

Not strictly correct... We use a small Yagi-Uda antenna attached to a handheld scanner (with signal strength meter!!).... Triangulation on the transmitted signal works well, and is simple and reliable, especially at extended ranges where you couldn't get a decent lock on the GPS data..

 

[RadioRon]

Not strictly correct... We use a small Yagi-Uda antenna attached to a handheld scanner (with signal strength meter!!).... Triangulation on the transmitted signal works well, and is simple and reliable, especially at extended ranges where you couldn't get a decent lock on the GPS data..

Nice to see someone using the right name for that antenna. Poor old Uda seldom gets any credit for this thing.

 

[Gaskell]

Have you tried the tx modules from Radiometrix or Laipac?

I use these modules for tracking rockets to altitudes over 20,000 feet, and ground recovery ranges of over 5 miles...

I've attacked a foto of a prototype... This one runs on 433.94mhz, and using a 120 mah, 9.6v nimh stack runs for about 4 days... If I tweak the code in the pic, it'll run considerably longer.

Now thats what I'm talkin bout!
Thats exactly what I'm after, 5 miles would be great and such a small circuit. Brilliant. Whats the size of the stack? I'm wonderin if you can send me a copy of the diagram and parts list. Then all I need is a rechargeable that can power it and a solar charging circuit of similar size to that circuit (That I think may be pushing it, but may be possible), then I got it all.
If the solar idea isn't possible (sizewise) then I'd need some other way to charge it but having a socket is a risk as it needs to be weather/water proof. The solar would be great because then I would never need to open it so I could seal the casing completely. Changing battey often would be too much hassle although I am going to work in a 'condition' switch that will only turn it on under certain conditions.
I'm sorry I have to be so vague about this but I have agreed to it so I'm bound by that agreement.