# How to calculate R and C for AM Demodulation envelope detection?

Discussion in 'Homework Help' started by Bilal12, Oct 22, 2015.

1. ### Bilal12 Thread Starter New Member

Oct 22, 2015
1
0
Hello , one question if posible .

How can I calculate the value of R and C for an Am envelope detection circuit.

Knowing that the carrier wave is 20KHz, 1Vpp, and the message signal is a 32Hz, 2Vpp, with a 5V DC offset:

and thank you .

2. ### GS3 Senior Member

Sep 21, 2007
408
35
So you have a 20 KHz carrier. That is a period T = 20 uS.

How does the circuit work. Think about it. How do you want it to respond to each carrier cycle. What happens if it reacts to slow or too fast. Think about it.

BTW, it seems to me this should go into the homework forum.

3. ### ErnieM AAC Fanatic!

Apr 24, 2011
7,443
1,628
I would think about this in the frequency domain. You need to pass 32hz but block the 20khz.

So what frequency would you pick for the cutoff?

Unless you have additional information from your instructor there are a wide range of values that work.

4. ### GS3 Senior Member

Sep 21, 2007
408
35
I suspect he hasn't done the frequency domain yet.