Personal Locator Beacon

[Joolz]

Hi all

I've recently learned about PLBs and EPIRB, which basically send distress signals with position information from the device built-in GPS. They can be relatively expensive, so I'm wondering if anyone has made any work towards a home-brew device?

Legal Disclaimer: haha, homebrew is a poor term. These devices need to be registered etc., so it's not recommended ( and actually unsafe) to build your own device. What I'm looking for is education on how these things work and general pointers on how to approach the designing of such a device.

 

[CDRIVE]

Actually, I believe an EPIRB operates in reverse of a GPS. A GPS is a receiver not a transmitter. While the EPIRB is a transmitter who's signal is received by satellites.

 

[Joolz]

The general approach I've got now is using a microcontroller to adquire data from a gps module when a button is pushed. This data is incorporated into a message body which consists of header, device id, position, etc. The micro then uses a transmitter (GSM or whatever) to send the data.

Notice I typed "GSM or whatever". I know very little about communications, and dont know how this could actually be implemented

 

[donkey]

well there are a few things you could try here, the problem with all is remote locations.
for example my samsung galaxy 2 has gps built in(as do most phones these days)
you could try to get someone to write code that will be a emergency button that can send out high pitch squeals, a sms to a designated number with longitude and latitude and make the phone flash alot all with a pin number. the issue is alot of outback areas(i am australian, so its outback, but any remote place is the same) does not have mobile phone reception
in alot of places there are CB transmissions with specific frequencies for emergency use. the problem here is however is if you broadcast a single message people may not be monitoring it. if you repeatedly broadcast (especially from mis-fire,unintentional activation of the unit) then you could be fine while someone who seriously needs the help can't transmit as you are jamming them.
there are satellite phones but I haven't played with them too much as yet. and I guess the cost of a call would be pretty high.
the option I would go with is pretty advanced and is what I used to use on my barrier reef trips. it was a CB locator that when activated would send a digital code to the boys at base (base... tin shed where we drank excessive amounts of alcohol... same thing right?) there CB would light up like a christmas tree and when one of them saw it they pressed a button which sent a signal back to my little waterproof container. the container would recieve the signal letting it know some one was ready to recieve the info, then it would transmit co ords to base which they could relay to police, ambo's whoever. back when I was playing with it it was conveniently put in a case that i could use as a floatation device too... dang thing weighed bout 20 kilos though as it included a few other things (yes I put beer in it.. I was young ok...)
this was built by a guy who passed away bout 3 years ago, and was just something he put together for us..... as for commercially viable products or how they work these days I have very little info, but the one I had was awesome..... I miss beer