But please let me know how much is that frequency i should detect...and what is the logic to detect those frequencies

 

Please check with your mobile phone service provider to determine what standard they support and consult the table to which Bertus linked in post #2 of this thread. By then you should know the frequencies and the standard communications protocol(s) and you can determine the (rather complex) details of decoding the signals from the standards.

 

Thankyou this is really helpful for me

 

can any one provide me the circuit for detecting 1.4Mhz frequency??

 

Frequency of what? Radio signal? Ultrasound?
Do you simply want to know if the frequency is present or not, or do you want to measure the actual frequency value?
What is the amplitude of the signal?

 

Frequency of radio signal...I want to know frequency is present or not...I dont know the amplitude

 

My service provider uses a frequency of 1.4Mhz in my area...So now my question is how can i detect this signal

 

See detector:

 

if you use a germanium transistor, the voltage will drop. some actually begin to conduct at .12 volts. silicon transistors have been used in crystal radios with a bit of bias applied.

 

1.4 mhz is easily tetected with a typical am reciever.

 

can any one provide me the circuit for detecting 1.4Mhz frequency??

Frequency counter? AM radio (American band)? Scope?

 

I think you did NOT* get the right specification. Cell phones work at much higher frequencies. There might be some wireless phone system such as ship-to-shore that works in the lower MHz bands, but cell phones need more channels than you could get in a lowe MHz band.

You might want to check again and also get the name of the standard. As an example, where I live GSM 900 MHz and GSM 1800 MHz are popular. Then there are layers on top of those standards.

* Edit: added word "NOT"

 

Moderator's note: A redundant thread has been merged with this one. Please do not open multiple threads on one topic.

 

Do you really mean 1.4MHz? 1.4GHz seems more likely.

 

I think you did NOT* get the right specification. Cell phones work at much higher frequencies. There might be some wireless phone system such as ship-to-shore that works in the lower MHz bands, but cell phones need more channels than you could get in a lowe MHz band.

You might want to check again and also get the name of the standard. As an example, where I live GSM 900 MHz and GSM 1800 MHz are popular. Then there are layers on top of those standards.

* Edit: added word "NOT"

yess my mobile works in 1800MHZ band

 

With this band how can i detect a mobile phone

 

I think we have visited this question before and failed to give you the information you seek. Please what you mean by "detect". If you just want to flash a light or wiggle a meter's needle, that is easy, If you want to decode the signal so that you can listen to voice communications or text messages for that phone, that is very difficult to achieve unless you clone the phone, and the SIM card (if it has one) in particular.

What, exactly, do you want to do?

 

I think we have visited this question before and failed to give you the information you seek. Please what you mean by "detect". If you just want to flash a light or wiggle a meter's needle, that is easy, If you want to decode the signal so that you can listen to voice communications or text messages for that phone, that is very difficult to achieve unless you clone the phone, and the SIM card (if it has one) in particular.

What, exactly, do you want to do?

I want to learn how to detect the phone signal...i.e if there is any phone sending a msg or call or receiving any message or call in a class room
my circuit should detect it and buzzer should ring

 

This circuit can do what you described if you change the LED to a low voltage buzzer.

 

Can you please tell me how this circuit is detecting the signal