call timer for mobile phones

[keile]

hello again!

i'm thinking of a device that would time a call that is separate from the phone.

It might use a LCD to display the call time. And I'm thinking of using a Cellular Phone calling detector to detect if a call is still in progress.

Its main application will be to inform the caller(user) if how long he has been on the phone.

Any insight would be much appreciated

 

[surajbarkale]

I found this while searching might be helpful http://www.techlib.com/electronics/cellhelp.htm

 

[trigger]

Please noted that the cell phone does not transmit RF signal continuously during calling...... thus you cannot use the RF signal as the indication of call time.....

just my opinion. ;D

 

[keile]

thanks for the reply ^^

Suraj:
wow.. very nice and helpful page! thanks!!

trigger:
uhh.. you think so? umm.. maybe.. oh well.. i have think about this, hehe, why not just bring a timer and use it while calling on the phone? i'm dumb

 

[trigger]

if you have a chance in access a spectrum analyzer, you will noticed that the cell phone isn't transmit continuously.

I suggested if you want to use the RF signal as the sourcce, you can use RF scottkey diode to pick up the RF signal, and sample its presence in a certain period of time, say for example 1s.

Hope this help