I need to make a Simple RF signal strength meter using PIC for a specific frequency e.g. 300 MHz Can any one help me with that ?

 

Hello,

Have a look at the RF building blocks page:
http://www.qsl.net/va3iul/Homebrew_RF_Circuit_Design_Ideas/Homebrew_RF_Circuit_Design_Ideas.htm

Bertus

 

well I need a simple one using PIC microcontroller so I can use it in my Graduation project i need it only to measure signal strength so I can detect distance between two objects

 

All the PIC has to do is be a DC voltmeter to display the resultant reading from a conventional RF signal strength meter circuit.
There are many such circuits on the 'Net & in Ham Radio publications.

 

Well , Thanks all of your help but actually I'm confused
Which circuit I need to measure Power of a specific frequency 300 MHz ?

 

More importantly, you need a detector circuit to determine field strength. No such device will indicate distance from the transmitter, just field strength.

A PIC could be used but a moving coil meter could equally be used and the system could then potentially be passive. You seem to be concentrating on the unnecessarily overcomplicated part of your design whilst ignoring the core system component.

 

Hello,

Did you have a look at the page I gave?
There is a section: RF Test Circuits
In there you will find RF power meters and field strenght meters.

Bertus

 

NOT any of circuits ... can get output for specific frequency as current or voltage !!

 

A PIC Cannot receive radio signals.

You will need an analog front end tuner and pre-amp. The output of the pre-amp can be demodulated either digitally or via analog, or the strength of the signal alone can be converted to a voltage level from 0-5V so the PIC can read that analog voltage.

If you are trying to implement "Software Radio", you will need a MUCH faster computing system.

In short, the PIC in the scenario you are describing would only be the output/user interface device. All of the radio level tuning/noise filtering/etc would need to be handled by an off-chip radio system.

 

I need to use PIC as a Voltmeter or Ammeter to measure Specific signal strength from an external circuit all I need is that circuit and it's details

 

I need to use PIC as a Voltmeter or Ammeter to measure Specific signal strength from an external circuit all I need is that circuit and it's details

Which circuit? The RF part, or using a PIC as a Voltmeter part?

You'll find tons of info on precision voltage measurement with PIC, up to about 9 bits of accuracy (1/512) to 10 bits (1/1024) if you use a precision external voltage reference.

The RF side, that gets more complicated.