# What is Fm: Definition and 113 Discussions

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1. ### Am vs Fm variable capacitor receiver, what is the difference?

What is the difference between a variable capacitor in a AM receiver and a variable capacitor in a FM receiver? I understand that Am is amplitude modulation and that the signal is carried over a changing amplitude and that the frequency is constant. And the opposite in FM signals. And a variable...
2. ### How is wideband FM implemented on the E4400B signal generator?

The Agilent E4400B (formerly HP ESG-something) is a <1GHz signal generator. One of its features is that it can take a <10MHz external signal and turn it into frequency modulation on the output carrier signal (like an incredibly wideband VCO). However, the device can also be externally referenced...
3. ### Minimum Frequency of FM Data / Catastrophic Error Scenario?

Ever since I learned about FM something's been bugging me, which is that the PLL error correction acts on the encoded data, seeming to leave open the possibility of the shape of the data itself interfering with the PLL's interpretation of what the carrier frequency is. It seems dangerous to mix...
4. ### AM, FM modulation, sidebands question

Hi, I wanted to refresh some knowledge, some years ago @berkeman helped me out with this , thanks. 1) In an AM modulation a fixed frequency carrier wave is amplitude modulated , where the amplitude represents the lower frequency information signal, this modulation of a signal that is amplitude...
5. ### Measurement of frequency deviation in FM signals

Hi all Is there any way to measure frequency deviation in a recorded frequency modulated time domain data? The little research i have done on net mostly concerns with frequency deviation measurement using spectrum analyzer in real time i.e. data continuously received on spectrum analyzer while...
6. ### I Calculating S Using Fm in a Magnus Force Equation

what is s in this equation and how what equation do I need to figure out what S is Fm = S (w × v) Where: Fm =the Magnus force vector w= angular velocity vector of the object v=Velocity of the fluid (or velocity of object, depends on perspective) S= air resistance coefficient across the...
7. ### Can you build an FM transmitter with a crystal oscillator

Can you build a fm transmitter with A crystal oscillator? I already have a 100 megahertz crystal oscillator. I can't find instructions on how to do That on the internet.
8. ### FM Ratio Detector is not working

hi , please can somebody help me about this circuit, is not working i don't get audio signal here is my circuit rename in asc frm txt thanks
9. ### FM converter (mixer) -- I don't understand

Hello, Can somebody help me,to explain me this circuits this is converter, but i really don't understand how it works( i understand mixers, you put rf to base and local oscillator to emiter, but this is a litlle bit complicated)
10. ### Can a Copper Coil Harvest Power from Power Lines for an FM Radio Receiver?

I had an idea of building an FM receiver that is powered from the electromagnetic fields generated by power-lines. My question is , how can I make the electromagnetic field receiving antenna? Will a simple copper coil work? If so, can the same coil be used as the RF antenna or will that have to...
11. ### Nyquist and FM and Signal Mixing....

In an assignment I have, we are told to implement a Frequency Modulating function without using any of MATLAB's in-built functions, and not to use it's integration function either (use cumsum instead). I've been getting a lot of problems trying to solve these assignment problems without telling...
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### [MCNP5] Error when use Fm, De/Dm with Fmesh

Hello everyone, I do need your help in this matter, please kindly help me solve this problem I use MCNP5 and i run a simple example using Fmesh4 and Fm, De / Df but I get an error: " fatal error. no tally associated with response function -1" " fatal error. no tally associated with fm card -1...
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### What is the expected coverage range for my FM radio station in Lahore, Pakistan?

Hello, I am from Lahore, Pakistan, I have obtained a FM transmission License in Lahore. and i am about to set my radio station here in few days. i have ordered the equipment which will reach here in 5-7 days more... here i am going to give you my broadcasting equipment details: now i am curious...
14. ### Finding the bandwidth of an FM signal

Homework Statement Consider the frequency-modulated (FM) signa A(t)=A0sin[2πfct+Δfsin(2πfmt)/fm] , where fc = 3.5 kHz, fm = 88.1 MHz. What is the bandwidth of the signal? [Note: You may take sin≅ and cos≅1 for x (in radian) << 1.] Homework Equations A(t)=A0sin[2πfct+Δfsin(2πfmt)/fm] The...
15. ### Why do AM and FM waves have different bandwidths?

Q1. Why are higher frequencies assigned a higher bandwidth? Reasons for asking the question: My book quote "FM came late than AM waves and had to use higher frequencies than AM... The greater range of frequencies available means that each station has a greater bandwidth..." If the equation is...
16. ### How did Armstrong's FM receiver and transmitter work?

Hey, I was wondering if any of you smart people could help explain in a very simple way (if possible) how the first FM transmitter and receiver worked? I know, for example, that many current transmitters use a voltage variable conductor to change the frequency of the wave. Did Armstrong do...
17. ### MCNP Simulation of Tokamak Energy Deposition

Hello there, I am using mcnp6 to simulate a tokamak. I am interested in the energy deposition in the blanket and I am using a fmesh4 and the tally multiplier fm4 as follow: fmesh4:n ORIGIN=0 -24.2 -50 OUT=CF imesh=35.2 iints=352 jmesh=24.2 jints=484 kmesh=50...
18. ### A Understanding the Impact of q=0 on Spin Entropy in FM and AFM Magnon Dispersion

How calculate the DOS from the one dimensional AFM and FM magnon dispersion relations given in Kittel? What is there limiting form as q -> 0, and how does this affect the spin entropy?
19. ### Fluid mechanics - impact of jet question

Consider a case- Force excerted on a stationary flat plate held normal to the jet. The Jet strikes on plate (see fig.) Which is smooth hence the exit velococity of jet = entering velocity of jet. According to theory. The fore is applied on plate due to change in momentum of jet. But my doubt...
20. ### Anything like GPS that receives FM signal & creates location

Hi everyone :) I'm working on a Pip-Boy project from the fallout series (making a real life functional one), and I was following the guide of someone who was using a raspberry pi to create it. As I was following along his work, he said that he was having problems with GPS not working indoors...
21. ### Help with understanding modulation in AM, FM and PM radio

I have a few questions about AM, FM and PM. 1. If FM (or PM) radio modifies the frequency of the signal, how is the signal picked up without having to change the frequency constantly? 2. If PM modulates phase, which modulates frequency, what is the difference between PM and FM? 3. Why is AM...
22. ### Can pocket FM radio output at 50kHz?

I've recorded the output hiss from a small battery powered radio operating inside a metal tin. From related posts, I can say that the radio is effectively shielded from receiving any FM transmission, and the resultant hiss is thermal noise in the early stages of the receiver. I believe that...
23. ### Armstrong's Modulation Method vs Wideband FM

Hey guys, quick question. Is the modulation scheme described here (Armstrong's Phase Modulation) simply wide band FM? This Wikipedia article lists the following patent for Ed Armstrong for "Armstrong's Phase Method" and "Wideband FM" 1933 Patent: http://www.google.com/patents/US1941068
24. ### FM transmitter not transmitting

I studied the working of the fm transmitter and end up making my own. The first part is amplifier and second (right) part is colpitts oscillator. The circuit works good on simulator. The output is AM modulated wave lying in fm band so it could be detected by radio easily but the circuit is not...
25. ### Is it possible to deflect or modulate a FM Transmission?

Can you use a speaker to influence a FM analogue radio transmission no matter how small? The speaker and antenna where about 2 m apart. The PC has an audio AMP added in of 20 W. see Drawing not to scale.
26. ### FM Radio Transmitter Solution: Help for Holiday Nightmare

hi all. I have been scouring the Internet looking for a forum to help me. This seems like my best bet. I live next to a house with an enormous Christmas light display. It causes traffic littering loitering and a blocked driveway. I have talked to the neighbors the police and the town for help to...
27. ### Model an FPGA FM Radio Demodulator in Python

I am trying to model an FPGA FM radio demodulator in Python. I will have a mixer that converts an FM channel to 36MHz IF, and I plan on undersampling this IF signal. If in the digital world (my Python model), I have a high sample rate FM signal at 1.2MHz, should I be able to resample to a...
28. ### Browser on computer causes interferance for low bandwith fm stations

Hi, I have a computer set up with a KVM switch. When using the computer and not opening a browser, IE or Firefox, the radio is fine. When I open a browser I get interference on the radio ... Low frequency on the fm bW in the 80 Mhz range. If I open both browsers it completely kills the...
29. ### Variable capacitor q factor for fm radio jammer

i'm building fm radio jammer for project for my ee class in physics department. a circuit is here. http://www.circuitstoday.com/fm-radio-jammer i bought the components, soldered on PCB. it hasn't worked. an oscilloscope shows sine oscillation even if there is no L and C for tank circuit...
30. ### What causes the capture effect in FM modulation?

My understanding of the FM capture effect is that if an FM receiver receives two, on frequency signals, it suppresses the weaker one and demodulates the stronger one, given that the difference in signal strength is significant enough. This differs from the case of AM where the two signals are...
31. ### Mass of sculpture given fm, mass, lengths etc

Homework Statement A heavy sculpture is suspended by a steel wire that is 91.0 cm long and has a mass of 5.40 g. In a strong wind, the wire hums at its fundamental frequency of 97 Hz. What is the mass of the sculpture? Homework Equations v = sqrt(T/μ) μ = m/L The Attempt at a...
32. ### FM Signal Complex Envelope: Understanding & Resolving Integral

Hey guys, I'm trying to understand the complex envelope of a Frequency Modulated signal. According to the Textbook by Leon Couch, the complex envelope of an FM signal, g(t) modulated by the signal m(t) is given by: g(t) = Ae^{jθ(t)} where A = |m(t)| and θ(t) = D_{f} \int^{t}_{-∞} m(σ)...
33. ### Frequency Division Multiplexing. FM SSBSC system. Bandpass Filter

Homework Statement Due to its bandwidth and power efficiency, SSBSC is commonly used in Frequency Division Multiplexing (FDM) systems. FDM systems are used to combine a number of separate information channels into a single transmission. Each channel uses a separate carrier frequency and the...
34. ### FM Analysis including Bessel Function

Homework Statement An FM broadcast system has the following parameters: *Deviation sensitivity 5 kHz/V. *Information signal consists of 2 frequency components; 12sin(2π10000t), 10sin(2π15000t). *Transmitter antenna impedance is 50Ω. a) What are the modulating indexes for the 2 components? b)...
35. ### Finding the times when one cycle occurs for FM wave

Hello everyone, I'm trying to find the times when one cycle occurs for a FM wave. For instance, given y(t) = sin(2∏f_{c}*t_{1} + sin(2∏f_{m}*t_{1})) at an arbitrary time t_{1}, I wish to find the time t_{2} such that (f_{c}* t_{2} + sin(2∏f_{m}* t_{2}) – (f_{c}*t_{1} +...
36. ### FM radio system for simultaneous translation

Maybe someone who knows about FM radio transmission equipment can help me. I'm the pastor of a 200 member church in Berlin Germany. I would like to build a small system to broadcast simultaneous translation. I would think all I need is an FM transmitter, microphone and FM radios or headset...
37. ### FM Radio receiver in RLC circuit with .200 microH Inductor

Homework Statement The tuning circuit in an FM radio receiver is a series RLC circuit with a 0.200 µH inductor a. The receiver is tuned to a station at 104.3 MHz. What is the value of the capacitor int he tuning circuit? b. FM radio stations are assigned frequencies every 0.2 MHz, but two...
38. ### Calculating FM transmission distance

Hi -- I am trying to calculate the signal distance for a 2kw FM radio station broadcasting with a 157' antenna over average terrain. The FCC calculator requires field strength, and I don't have a clue what that would be. Can I roughly calculate broadcast distance using the known variables...

Hi there. I have a (hopefully) quick question here. FM radio stations transmit their information by manipulating the frequency of radio waves, but each radio station is assigned to a specific frequency. If the frequency broadcasted by a radio station is constantly changing (to transmit info)...
40. ### Can You Convert an AM Spice Rack to FM?

Convert AM...spice rack... To FM? Seriously, this "antique" was a cool little find on our northern road trip and looks neat in our Kitchen (see attached photos). But it's only AM. I'd like to make it FM. I'm not a major electronics hobbyist, and definitely not an engineer, but I mess with...
41. ### Exploring FM & AM: Questions & Answers

Hi guys. Two questions: 1. AM, as opposed to FM, is closer to what FFT is naturally used for right? 2. Is there a physical reason why FM is used in higher frequency bands and not AM? Could, for instance, FM be in the AM band and vice versa? Would transmitting, hypothetically, AM signals in...
42. ### How do Radio Waves work when used for FM or AM Radio transmission?

I would like to know about radio waves used for FM or AM radio. I have read many articles that say, "The sound is encoded and rides on a carrier radio wave". How is that encoded? I am under the assumption that waves just have a frequency and wavelength and that is all. If a wave is transmitted...
43. ### Transmit With 5W FM Transmitter & Dipole Antenna: Range & Radiation Pattern

With a 5W FM transmitter and a normal dipole antenna , to what range can I transmit. To be more specific, what will be the radiation pattern like (Can I get signal uniformly as in a circle where the center is antenna). Using which antenna, can I achieve maximum range omnidirectionally...
44. ### Stereo indicator light in FM radio

Homework Statement How does the stereo light in an analog FM radio turn on when you tune into a stereo station? The Attempt at a Solution I know that radio tuners work on the concept of resonance. Current and voltage levels spike up at and near the resonant frequency of a circuit...
45. ### So if FM radio signals modulate the frequency of the EM wave

then how can you tune into, say, 101.1 when its not at 101.1 MHz all the time given the frequency change?
46. ### How Do You Calculate Component Values in an FM Transmitter Circuit?

Homework Statement Hi I am weak at circuit, but I need to analyse how this circuit works and to determine the values of C4, C5 ,C6,C7, and L1. I need help for the understanding function of the whole component and determine the values of these component Homework Equations f=1/2√LC...
47. ### Why AM & FM Broadcasts at Certain Frequencies?

Hello, looking at the attached graph of noise voltage to frequency, I am trying to understand (from a noise point of view) why AM and FM broadcasts at the frequencies they do ? Can anyone offer any suggestions please ? Thank you.
48. ### Can someone explain the workings of this FM transmitter circuit in detail?

I am a beginner at circuit design.i need to find a way to explain how an fm transmitter works which i do not so any of you my sincere friends can explain to me how the circuit below works and does the necessary calculations I'm in your debt Here is sample proteus file and circuit diagram :
49. ### Low Power FM transmitter explanation

Hello everyone, Finally I found a useful website where I can find the answers of my questions:) I will take signal processing course soon and I thought "building a low power fm transmitter" is a bright idea to train myself to a certain level... Though I need your help and I don't have...
50. ### FM Amplitude vs. Frequency Spectrum

I know that an AM Amplitude vs. Frequency Spectrum has a central frequency = carrier frequency and two side bands of carrier frequency ± signal frequency. Now what would a similar spectrum look like for an FM wave ? My textbook just says that '... further side frequencies that are...