I'm researching a project at the moment to embed a SMS activated GPS tracker in a bike. My old bike was recently stolen and I'm researching this in a bid to prevent it happening again!
My current thoughts / general approach is to seek to build a small board that'll fit in the saddle post of the bike, the inner diameter of which is around 22mm or 0.866 inches.
My main worries are that all the small GPS and GSM units available at the moment might have a hard time with signals while they're in the metal frame of the bike which is made of steel.
I'm considering a GPS unit with an external antenna that could be mounted outside of the saddle post and instead on the external bottom face of the saddle itself.
The reason for placing the components in the saddle post is that they would be more easily accessible to change the battery pack out. I'm also considering placing other components elsewhere in the bike and running wires through the frame if needs be.
I'm a software developer with very limited electronics experience and I realise this is likely a large-ish project with which to tackle the learning curve so any help would be greatly appreciated!
If the bike is valuable enough to warrant antitheft, my recommendation is a professional product. If you can build something approaching the commercial footprint with similar performance - go for it. My buddy had $2K in his bike and it was stolen right out of the corporate parking facility with RFID security and humans and CCD. My idea is "blow-jack" a bike ejection seat, remote controlled, that will blast the perp into orbit for those who believe revenge is more valuable than recovery.
Seems to me that it would be better to focus on ways to stop it being stolen - i.e. stronger locking mechanisms and better discipline about using them. Adding tech to your bike just increases the amount of stuff you lose when the bike is stolen.
Since you are somehow connecting to a cellular service to get SMS messages, why don't you investigate trying to triangulate your location based on the tower signals instead of GPS. Just a thought.
sparkbug:
Since you are somehow connecting to a cellular service to get SMS messages, why don't you investigate trying to triangulate your location based on the tower signals instead of GPS. Just a thought.
No, that works the other way around. The towers can triangulate you, but you need an interface to their infrastructure.
Paul__B:
No, that works the other way around. The towers can triangulate you, but you need an interface to their infrastructure.
Nowadays there are crowd-sourced databases of cell tower locations that make it possible to get an approximate geographic location (typically to within a few hundred meters) given knowledge of accessible GSM cells.
I don't think that would be good enough to find a stolen bike, but it might help in "Dude, where's my car bike?" type scenarios.