[Question] Carrier wave strength detection w/ PIC18F452

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[Question] Carrier wave strength detection w/ PIC18F452

Postby Advantage » Sun May 20, 2012 2:24 am

I am working on a project right know where I have created a simple transmitter and receiver circuit. The transmitter sends out a carrier wave at 24MHz with no intelligence on it. I am trying to make it such that when I get closer to the transmitter with my handheld receiver it will light a series of 5 LED's. Right now I am trying to use the PIC18F452 to do this using the built in ADC. The more and more I read about ADC the more confused I become as to how I might achieve this because originally I was going to do tests to figure out what my maximum received voltage is from my transmitter to my receiver and set that as the max and use 0V as the minimum however, it seems to be that you need to have your maximum and minimum voltages plugged into pins 4 and 5 on the DIP and since I am using radio waves which cannot be plugged in I am confused as to how this might be done. So my question is do you think this is possible with the PIC18F452 and how might someone more experienced than me go about doing this?

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Re: [Question] Carrier wave strength detection w/ PIC18F452

Postby ThePyroElectro » Tue May 22, 2012 6:18 am

Hi Advantage,

I'm not 100% clear for what you are trying to achieve but I can clear up a few mysteries about the PIC's ADC.

The PIC has many different ADC modes. The first mode you can set is that the Vref- is ground and Vref+ is PWR (+5v or +3.3v probably). The case you described means you can feed in a Vref+ and Vref- to pins 4/5 and then the analog comparators will use those two voltages as a scale from 0-1023 (PIC has a 10 bit ADC) to give you a digital value.

You can see this article:

For a simple example of using the ADC to capture a low voltage audio signal and display and instantaneous voltage amplitude on an LED bar.

Good luck!

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