help me to bulid a bird tracking system

Hi,all
I want to know the realtime-location of my pigeon. now I think GPRS + GPS is a feasible solution.
So I have found some modules like SIMCom SIM548C,but a little bigger. Have anyone give some suggestion?
Thanks!

I think any available module GPRS+GPS+Control Interface+Battery+Antennas would be much heavier for a pigeon.
Try a bigger bird, but not sure if it will return to you...

There are systems around which will cover bats & small birds GPS devices for birds

Keith.

All the systems in the link above use only GPS loggers, and no GSM/GPRS communication, which actually would be the problem to meet the low weight requirement.

Scince your application is for a pet pegion my option is GPS with Zigbee module. Zigbee modules are compact, low operating voltage and power, easy to program. You can install three or more Zigbee receivers at your friends/ neighbours home and communicating with pigeons module from all receivers you can get the pigeon location. otherwise with Zigbee protocol tracking you can find approximate direction or l0cation of your pigeon with out GPS also.

SIM548C is probably based on a GSM module from Telit with GPS functionality. It is possible to build a small Telit circuit with a simple low power MCU that do what you want. The main problem is probably power budget in relation to weight for the power source. Have no idea what weight that can be accepted for a pigeon but already 50 gram sounds heavy. For development board or plans for a such circuit can devices - GROUND Lab Wiki be a good start. For a smaller and less heavy circuit can a Chinese GSM wristwatch in combination with a small GPS unit be a possibility, but that would be rather complicated hacking and still you have the problem how to keep down weight of power source.
A possibility to reduce power consumption is to activate GPS circuit very seldom and GSM circuit even more seldom, depending on how GPS data have changed or GPS buffer size. Solar-cell in combination with a small buffer accumulator can be a alternative light weight power solution that I think have been used for tracking of small animals. Then is information transmitted only if the accumulator is charged enough.