GPS & RF tracker

Hi all,

I hope im posting in the correct place, apologies if not.

I am starting a vehicle tracking and recovery business and need some advice / help/

I am to provide a battery powered GPS tracker to my clients, i would also need to have a VHF / UHF beacon with it. Idea is to use the GPS location to see the area that the vehicle is in and then (if needed) use a hand held RF receiver to pinpoint the asset in buildings, containers, vehicles if the asset is hidden out of site. Ideally the RF will be activated when i put the tracker into find / alarm mode.

Now i know nothing at all about electronics, is this as simple as attaching a RF transmitter chip to the battery power of the GPS system or is there alot more to it?

Many thanks for taking the time to read my post

You are in the right place but your requirements are not clear.

A GPS receiver can pinpoint the location fairly accurately already but you need a long range (mobile phone?) network to tell you what the GPS location is. A beacon alone won't help. you also need some way to remotely turn the beacon on, I wouldn't advise it running continuously as it would have to share air space with lots of other devices using the same frequencies.

After that, yes basically you can 'home in' on a low power beacon using direction finding equipment. That could be a simple antenna and signal strength meter to tell you which direction the signal emanates from. You might want to consider pulsing the beacon say once every few seconds with some data to be able to distinguish it from other devices. You must consider that the band you would be allowed to use is shared with vehicle remote locking, wireless doorbells, wireless weather stations and many other devices. I am in a very remote rural location and even here I can pick up maybe ten or more devices around the designated frequencies.

Brian.

Hi Brian,

Thanks so much for your reply.

Thank God you have the jist of what I'm asking. The trackers we will have will be battery powered (5-7 year battery) and will be in a low powered sleep mode, they will only operate for a few seconds per day to send us a position every 24 hours.

If/when an asset is stolen we can alarm the tracker which will report location every 60 seconds. Obviously when we have alarmed the tracker it is fully awake and drawing constant power from the batteries. What I would like to do is somehow attach a low power vhf / uhf beacon into the battery power that will send, like you say a pulsed beacon that we can physically track when the item has been hidden out of plain site (in a shipping container, van, house etc).

What kind of rf transmitter would you suggest, small size obviously, and would you think it's a big job to join the two devices together?

Again many thanks for your time on this !

Regards
Chris

There is a company local to me that do something very similar - for some reason they keep bombing me with offers to update the trackers on my truck. It might be useful if I had one but my little Toyota Yaris rarely carries anything of value and I'm the only one that drives it!

Back to technical matters, there are numerous challenges ahead of you. The biggest will be that if the tracked item is indeed inside a shipping container or any other screened 'box' it will not be able to pick up GPS signals at all. Second biggest issue will be the battery life, even if it periodically wakes up and checks its location, it could be active for quite a long time while it gets a GPS fix, typically the receiver will continuously try until it gets one. It then has to try to establish a link to a cell station to be able to send information back to you. It is certainly possible to do but be aware of the pitfalls from the outset and understand it will not work in all situations.

However, if all the above works, your best bet for pure direction finding is a really cheap ASK transmitter pulsed for say 100mS once a second. Keeping the pulse on/off ratio low will preserve battery life but there has to be some compromise so that a DF receiver has chance to measure the signal level.

Brian.

GSM supported GPS will help you to implement such system without any difficulty.You cannot receive the necessary information wherever the vehicle is due to limited distance,geographic obstacles.There are many GPS+GSM Modules to build up such system in the market.

Thanks Brian & Bigboss,

GPS will be the main point obviously, the pulse beacon will only be used if the police do not find anything at the given co-ordinates and we have to do a manual search, obviously starting at the last known GPS point. Thanks again, I just need to find someone with a clever brain who can put the two together.

I bought while ago this cheap GPS/GSM tracker which works amazing well. Location precision is in a range of few meters.
On top of location, and using GSM, it send also (by request) the nearby sounds. So if the car was stolen (or who wear the tracker) you get the voice of the thieves...
13 bucks are unbeatable, at least when you don't have much experience designing something like this.