How to detect signals from mobile phone to tower

[electro_fran]

Hello everybody,
I'm designing a mobile phone detector. My approach is to work with the GSM uplink frequency range. For this purpose, my questions are:
1- When a mobile phone is not in communication (call or SMS), what are the signals that it sends to the tower?
2- The most important for me, what is the period between these signals?

 

[udayan92]

Answers:
1-The mobile,at a fixed rate,sends signals to the nearest tower(s),which enquire whether is any call/sms waiting to be received by it or not.Apart from this,it also includes time sync signals.
2-No idea about that.Try using a real time signal monitoring system around the cellphone to see what signals are being transmitted/received.

 

[electro_fran]

Can the RF power detector be used as real time signal monitoring system?