Logarithm in PBP

[Pic_User]

Hi Savnik,

If I read your problem correctly:

I have a linear for FM and i want to measure the power.
From the power meter i take the indication which is in volt. This volt I want to show on LCD. But the power change in logarithm scale and this is my problem.

My english is not so good.
I want the voltage which measure with the pic , to show on lcd in dBm or dBv or watt (the table which post in #6)

You have a RF amplifier that has an analog power meter. The power meter reads a voltage and displays the power on a Logarithmic scale. The input, to move the meter, is voltage. The scale painted on the meter face is logarithmical.

You need the PIC’s adc input to read the DC voltage running the meter and then using mathematics or a “look-up” table convert the voltage to the equivalent power in Watts. You have already calculated the table, posted in your previous post.

Is this close to the question? I am just trying to help with clarifying the question. Sorry I don’t have an answer for you.

-Adam-

[savnik]

Hi Savnik,

If I read your problem correctly:


You have a RF amplifier that has an analog power meter. The power meter reads a voltage and displays the power on a Logarithmic scale. The input, to move the meter, is voltage. The scale painted on the meter face is logarithmical.

You need the PIC’s adc input to read the DC voltage running the meter and then using mathematics or a “look-up” table convert the voltage to the equivalent power in Watts. You have already calculated the table, posted in your previous post.

Is this close to the question? I am just trying to help with clarifying the question. Sorry I don’t have an answer for you.

-Adam-

Yes, it is my question.