Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [fm]

For questions relating to frequency modulation (FM). This is a scheme where a carrier is modulated by varying its frequency to carry information.

-1
votes
2answers
7k views

How to remove the static sound in an fm transmitter

Hi I have a school project and I used the schematics from this website for our FM transmitter. Its actually working but its hard to recognize the music being played because of the static, also does ...
4
votes
1answer
187 views

What antenna is this?

I just disassembled an external FM antenna designed for an old Asus laptop. I expected to find some circuitry and a monopole or some other simple antenna. However, what I found was the antenna shown ...
1
vote
1answer
69 views

how to calculate the maximum radiated power for the FM broadcasting?

I am trying to experiment a fm transmitter project of Raspberry Pi - with a frequency of 88.1 MHz. http://icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into_an_FM_Transmitter However, I ...
0
votes
1answer
422 views

Is it true that frequency deviation over 2*pi is the phase deviation of an FM/PM signal?

for ∆f frequency deviation if for FM only and PM has Phase deviation. and Kf= ∆f (Hz) of FM? Kf = ∆f (rad/s) for PM? and for th rules: ∆f=(kfmp)/(2p) for FM where mp = mp max-mp min ∆f=(kfmp)/(2p) ...
0
votes
1answer
86 views

Audio transmitter - frequency customization from a simple FM transmitter

I am referring the following circuit diagram. Circuit Can I simply change the value of C2 and L1 to transmit at a frequency below commercial FM band say as low as 40 Mhz? I know, I need to make a ...
0
votes
1answer
151 views

For which purpose are those resistors on the ANT output?

I've bought a cheap FM transmitter and installed it in my car, but sadly, it gives me too much interference (Too weak signal), even in a totally static signal, so I decided to disassemble the ...
0
votes
1answer
34 views

Noise floor of a FM duplex

If these 2 signals, that form this duplex, have ranges of 15-30 [kHz] and 30-45 [kHz] using: \$NoiseFloor_{dBm} =10\log _{10}(k\times T_{0}\times 1000)+NF+10\log _{10}(BW)\$ and if \$K,T,F\$ and \$\...
2
votes
0answers
71 views

High SNR FM demodulation

So I need to demodulate the FM signal from a sensor with highest SNR possible, at least 70-75 dB. IF is 10.7 MHz, max. deviation is 200 kHz but I can change those values if needed. Baseband signal ...
2
votes
0answers
249 views

Matlab Phase Locked Loop Design : FM Demodulation

EDIT: It seems I've asked too much at once here. I'll do some more studying and come back if I have more specific questions. I'm trying to design an analog phase locked loop in Matlab. I've read ...
2
votes
0answers
492 views

Is it possible to make a Raspberry Pi transmit FM on several frequencies at the same time?

I have read a few questions here on transmitting on multiple frequencies at the same time. But all of them was about transmitting the same signal to all frequencies. The PiFM and PiTX projects are ...
1
vote
0answers
101 views

Phase Locked Loop Gain Design- FM Demodulation

Say I am trying to demodulate a message up to 25kHz in frequency, with a peak frequency deviation of 75kHz and a carrier of 1MHz, implying a 200kHz bandwidth using carsons rule. Would I design the ...
1
vote
0answers
286 views

Superheterodyne receiver with voltage controlled oscillator

I'm new in electronics and I want to create a FM receiver that performs a product of the received RF signal and a local signal (the local signal is also frequency modulated with a Voltage Controlled ...
1
vote
0answers
1k views

simple schematic for 10.7MHz crystal-based marker generator

For FM tuner alignment purposes I want to build an outboard 10.7MHz marker generator to use in association with a piece of gear (ST1000A) that doesn't have one built in. They used to be available in ...
1
vote
0answers
106 views

Frequency modulation occurs not in an expected way

I've built this oscillator. Then I gave it a DC bias and connected an mp3 player. Result: I have local fm-stations muted at 90MHz, 90.75MHz and 89.25MHz. However, at 90MHz an mp3 music is very ...
1
vote
0answers
296 views

Good compact antenna for FM audio transmitter module?

I've been looking at building a short range FM transmitter using this module, the idea is to create a small module that I can integrate into other projects. I'd prefer having the antenna on the same ...
0
votes
0answers
29 views

Frequency Modulator with sinusoidal output

I am creating a frequency modulator, all the circuits that I have looked so far on the internet are generating a Pulse wave or a Triangular wave output, so if you guys can help me to create a circuit ...
0
votes
0answers
35 views

Connecting an FM radio receiver circuit to a speaker via 3.5 mm audio jack?

As an experiment and for educational purposes, I wanted to build and connect an FM receiver to some old computer speakers via a 3.5 mm audio jack. So I tried building a circuit like this on a bread ...
0
votes
0answers
122 views

Keeping constant bandwidth in tunable quadrature FM demodulator

I need to demodulate an FM signal (4 MHz max deviation) with a strong center frequency drift (550-800 MHz). I've built an AFC circuit to track the drift and now I need to build a tunable quadrature ...
0
votes
0answers
65 views

Antenna cable pin-out identification

I am trying to connect a stock car FM/AM antenna with a new aftermarket stereo system, Turns out my car antenna has 2 wires. One is Co-axial cable for signal (Most probably) and there's one more ...
0
votes
0answers
274 views

Phase Modulator with JFET

At the university we have seen this circuit as a Phase Modulator: simulate this circuit – Schematic created using CircuitLab where \$m(t)\$ is the message at audio frequency and \$v_p(t)\$ is ...
0
votes
0answers
55 views

Make Si4703 evaluation board Bluetooth capable

While looking for a Bluetooth RDS-TMC receiver which could be queried with FOSS software, and after realizing there’s probably not too much on the market, I stumbled across Si4703 evaluation boards ...