1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Designing a FM radio receiver

  1. Nov 14, 2007 #1
    1. The problem statement, all variables and given/known data
    Designing an FM Radio Receiver. You enjoy listening to KONG-FM, which broadcasts at 96.6 MHz. You detest listening to KRUD-FM which broadcasts at 96.5 MHz. You live the same distance from both stations and both transmitters are equally powerful, so both radio signals produce the same 1.0 V source voltage as measured at your house. Your goal is to design an L-C-R radio circuit with the following properties: i) It gives the maximum power response to the signal from KONG-FM; ii) the average power delivered to the resistor in response to KRUD-FM is 1.00% of the average power delivered to KONG-FM. This limits the power received from the unwanted station, making it inaudible. You are required to use an inductor with L = 1.00 ┬ÁH.

    a) Find the capacitance C that satisfies the design requirements?
    wrong check mark F
    (b) Find the resistance R that satisfies the design requirements?

    2. Relevant equations
    wL = 1/wC when at max. power and the angle phi = 0 degrees
    but i am having trouble with the 1% of the power part of the problem and how to involve that into this.
    96.6 MHz = 606955700.7 rad/sec
    96.5 MHz = 606327382.1 rad/sec
    L = 1.0e-6 H
    V = 1.0 V

    3. The attempt at a solution
    C =1/(w^2)L
    How do I involve the power into this?
    Pavg = 0.5*Imax*Vmax*cos(phi)
    Pavg = Irms*Vrms*cos(phi)
    Pavg = (Irms^2)*R
  2. jcsd
  3. Dec 4, 2007 #2
    This is a screenshot of the solution from a PDF that I found. I had a little bit of trouble with the same problem.

    This helped me figure it out.

    Came across this in google, I am probably too late though.

    Attached Files:

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook