0
$\begingroup$

This is my extra credit assignment so don't tell me answers, but please guide me how I should do this. I need to learn.

Question states: Determine the power output of the receiver in watts and in the appropriate measure of dB

let: Pin = 2W

diagram: --> [ G1 = 1/4 ] --> [ G2 = 1/10 ] --> [ G3 = 20 ] -->

How should I start?

After some thinking..

I'm not sure but G might represent the General formula which is G = Pout/Pin

EDIT

Is this correct?

Pin(dB) = 10log(2W/1W) = 3.01dB --- as input

dB = 10log(1/4) + 10log(1/10) + 10log(20) = -3.01dB --- As output

So the output at the destination is 0?

  • 0
    What are G1, G2 and G3 and what are the numbers 1/4, 1/10 and 20 associated with them?2011-11-30

2 Answers 2

1

You did it correctly! Great job!

  • 1
    Thank you! In my class professor got the same answer.2011-11-30
0

Hint: Search for transfer function and Bode Plot

  • 0
    @HelpNeeder I have a feeling about the question but you provide so little info about the diagram that I don't even know, if we are talking about the same thing. Transfer Function is a function that relates an input to an output. Its bode plot shows how the power is distributed among frequency spectrum but again, this is guessing.2011-11-30
  • 0
    @HelpNeeder Just tell me what Diagram > means.2011-11-30
  • 0
    This is basically what looks like on my problem: -->[G1]-->[G2]-->[G3]--> Meaning that I have 3 boxes, first 2 are reducing a signal, and last one acts as amplifier. So I have 2W input and what the output should be after last box.2011-11-30
  • 0
    @HelpNeeder :D See, this is completely different from what you ask. OK, they are simple gain blocks in series hence you can multiply to obtain just one block and the $G$ blocks are processing the signal I suppose.Do you know how to calculate the power of the signal?2011-11-30
  • 0
    I have an idea, but I'm not sure if I'm correct. What I know is in my last edit in OP.2011-11-30
  • 0
    @HelpNeeder Let say, we have a constant signal with magnitude 1, it has 1 unit of power per second and if it is amplified by 2 then the output will have 4. What you need is to apply the same principal to your problem.2011-11-30
  • 0
    I don't understand how you got 4. So you saying 2W x 1/4 should be output of my first block?2011-11-30