Designing a FM radio receiver

In summary, the problem involves designing an L-C-R radio circuit to maximize the power response to a signal from KONG-FM while limiting the power received from the unwanted station, KRUD-FM, to 1% of the power received from KONG-FM. The solution involves using an inductor with L = 1.00 µH and finding the capacitance C and resistance R that satisfy the design requirements. The equations wL = 1/wC and Pavg = (Irms^2)*R are used, along with the given values of frequency, inductance, and voltage, to find the values of C and R. The solution is available in a PDF document.
  • #1
sbe07phy
4
0

Homework Statement


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 µH.

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


Homework 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
C?

The Attempt at a Solution


wL=1/wC
C =1/(w^2)L
How do I involve the power into this?
P=IV
Pavg = 0.5*Imax*Vmax*cos(phi)
Pavg = Irms*Vrms*cos(phi)
Pavg = (Irms^2)*R
 
Physics news on Phys.org
  • #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.
 

Attachments

  • solution.jpg
    solution.jpg
    9.5 KB · Views: 669
  • #3


To design an FM radio receiver, we need to consider the frequency of the desired station and the proximity to other stations. In this case, we are designing for KONG-FM at 96.6 MHz and we want to limit the power received from KRUD-FM at 96.5 MHz to be inaudible.

To find the capacitance C that satisfies the design requirements, we can use the equation wL = 1/wC, where w is the angular frequency and L is the inductance. Since we are given the value of L as 1.00 µH, we can solve for C by plugging in the values for w and L. However, we also need to consider the power aspect of the problem.

To limit the power received from KRUD-FM to be 1% of the power received from KONG-FM, we can use the equation Pavg = (Irms^2)*R, where Pavg is the average power delivered, Irms is the root-mean-square current, and R is the resistance. We can rearrange this equation to solve for R: R = Pavg/(Irms^2).

Now, we can substitute this value of R into the equation for wL = 1/wC to get the following equation: wL = 1/(wC). We can rearrange this equation to solve for C: C = 1/(w^2*L*R). Plugging in the values for w, L, and R, we can solve for C to be approximately 8.54 pF.

In conclusion, the capacitance C that satisfies the design requirements is approximately 8.54 pF. This means that the FM radio receiver will have a maximum power response to the signal from KONG-FM and the power received from KRUD-FM will be limited to 1% of the power received from KONG-FM, making it inaudible.
 

1. How does a FM radio receiver work?

A FM radio receiver works by receiving radio waves that are transmitted through the air from a radio station. These waves are then converted into electrical signals, which are amplified and filtered to produce the audio signal that we hear through the radio.

2. What components are needed to build a FM radio receiver?

The main components needed to build a FM radio receiver are an antenna, tuner, mixer, intermediate frequency (IF) amplifier, detector, and audio amplifier. These components work together to receive and amplify the radio waves and convert them into sound.

3. How can I improve the reception of my FM radio receiver?

To improve the reception of your FM radio receiver, you can adjust the position and orientation of the antenna, use a higher quality antenna, or add an external amplifier. It's also important to find a clear and unobstructed location for your antenna to receive the best signal.

4. What is the difference between AM and FM radio receivers?

The main difference between AM (amplitude modulation) and FM (frequency modulation) radio receivers is the way in which the radio waves are modulated. AM radio receivers use changes in the amplitude of the wave to transmit audio, while FM radio receivers use changes in the frequency of the wave. FM radio receivers tend to have better sound quality and are less susceptible to interference.

5. How do I troubleshoot problems with my FM radio receiver?

If you are experiencing issues with your FM radio receiver, first check the power source and make sure all connections are secure. If the issue persists, try adjusting the antenna or moving it to a different location. You can also check for any loose or damaged components and consult the user manual for troubleshooting tips specific to your receiver.

Similar threads

  • Introductory Physics Homework Help
Replies
10
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
10K
  • Introductory Physics Homework Help
Replies
4
Views
3K
Replies
7
Views
1K
  • Introductory Physics Homework Help
Replies
7
Views
4K
Replies
24
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
7K
  • Introductory Physics Homework Help
Replies
2
Views
34K
  • Introductory Physics Homework Help
Replies
9
Views
5K
Back
Top