Questions tagged [frequency-modulation]
For questions relating to frequency modulation (FM). This is a scheme where a carrier is modulated by varying its frequency to carry information.
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SIMULINK: The spectrum of the modulated signal remains unchanged despite modification of the modulation index
I try to implement a frequency modulator.
From what I know, the more I vary the modulation index (which is set by the gain block here,) the more the spectral lines should increase in number.
When I ...
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Output levels of FM broadcast signals
I wrote an FM mono transmitter with HackRF, and now I'm trying to add stereo and RDS. I'm confused about the levels of the final mono + stereo + RDS mix (after preemphasis, and before the FM modulator)...
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Ratio detector FM demodulator
The aim of the exercise is to design a ratio detector FM demodulator circuit.
UPDATE:
I changed the circuit:
This is my transient analysis in output:
I found the information about AC analysis and ...
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Uniden BC780XLT Radio scanner, unknown modification
I recently purchased an old Uniden BC780XLT scanner. It has been modified replacing two smd resistor with THT resistors with different values. I am curious about this modification: what does it do?
I ...
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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 ...
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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 ...
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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 ...
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What can be done to increase the dynamic range of a FM receiver?
If i have to receive a signal from a far away FM station, nearby stations swamp the receiver if they are both nearby physically or nearby in the spectrum. I believe the AGC in my radio is cutting out ...
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What could be blocking communication with TDA7706S on a Sony GT520U radio?
I have a Sony GT520U radio which started developing a lot of noise and becoming unresponsive when in tuner mode. Opening it revealed the chipset on the tuner was overheating in less than 3 minutes of ...
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Modern approach of creating VHF FSK (FM) recieeiver
I need to make a narrow band FM receiver for the VHF band. More specifically, not even FM, but FSK. The operating frequency range should include from 35 to 40 MHz. Frequency deviation is around 0.5 to ...
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instataneous frequency in FM
Newbie and trying to understand the concept of instantaneous frequency in FM.
Basic equation is \$A\cos(2\pi f_\mathrm{c}t+ 2\pi k\int (\mathrm{message})\,\mathrm{d}t)\$. I wanted to know how the term ...
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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 ...
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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 ...
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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 ...
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Simple schematic for 10.7 MHz crystal-based marker generator
For FM tuner alignment purposes I want to build an outboard 10.7 MHz 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 ...
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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 ...
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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 ...
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How phase is modulated according to our message signal?
My question: let message signal m(t) be sin(w1t).For frequency modulation (instantaneous phase deviation=phi(t)) d[phi(t)]/dt=kf m(t) so i get that at 90° or π/2 frequency will be max because the ...
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IQ data for analog FM modulation
I am trying to understand how I can produce analog FM modulation using IQ data.
So far, I know to generate the FM modulation with an IQ modulator (like the LTC5599.) I have to apply IQ data in ...
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Frequency upconversion from 1 to 100 MHz for FM transmitter
I'm trying to build an FM transmitter like pifm but using the ESP32. I can generate an FM signal at the DAC output of the ESP32 with a carrier frequency of 1 MHz and a deviation of 25 kHz, but in ...
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Need help with signal modulation
To capture a mammalian cell, I need to have a constant 4MHz AC signal (coming from a function generator) while sweeping the frequency from the vector network analyzer (VNA) 9kHz to 9GHz to read the ...
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Band selection circuit for SI4825 A10
Following the official schematic and guideline (AN738: Si4825/36-A
Antenna, Schematic, Layout, and Design Guidelines), I am building a Si825 A10-based radio receiver.
I am getting weak audio output ...
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How decreasing the effective load impedance in the secondary of a transformer heavily dampens it?
I am reading the operation of the ratio detector for FM demodulation. It works on the principle of diode variable damping (please see the figure here). The capacitor C9 restricts the changes in the ...
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FM receiver With LM386 - Need a Preamplifier
I am building a hoppy FM Receiver and I created the Preamplifier stage 1 and linked it with the LM386 Stage and it goes OK but The output sound from the Speaker is weak so I tried to do some ...
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How Does Varactor AFC Work in This circuit
I have a question about how the varactor on the transistor's emitter can change the frequency of the modified Colpitts oscillator on the collector of this circuit. The junction of the varactor and R30 ...
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SI4735-D60 chip no FM signal reception
Trying to tune the SI4735 chip to an FM station.
Have using this library and example to drive the chip with Arduino UNO and based on the console output from the sketch the control interface works fine:...
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Bessel function if frequency modulation and modulating index
If amplitude of a message signal is kept fixed and frequency is increased then modulating index will decrease?
According to bessel function side tones will be more spaced if frequency increases but if ...
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FM antenna isolation
I want to connect a car antenna (FM radio) to a phone's jack sleeve to provide a good antenna signal to the phone (for its FM radio part).
As the car might add some supply DC to the antenna, I decided ...
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How to check for frequencies with stronger signal in FM radio
I'm making a radio player using si4703 IC. I read RDS data to know the radio station name, PI code, etc.
I also get the list of alternative frequencies (AF) that the radio station send via RDS. ...
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Fm receiver circuit doubt
I was trying to simulate an FM receiver circuit on LTSpice.
The circuit is given on this website
I want to know how the correct current/voltage will look around the speaker (modelled as 8-ohm ...
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FM demodulation (not!) using PLL?
I have to demodulate a square wave FM+PWM modulated signal, so for the FM demod I'm using a PLL with a positive edge sensitive comparator to lock on frequency only (CD4046BE). Carrier frequency is ...
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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 ...
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540
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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 ...
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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 ...
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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 \$\...
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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 ...
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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 ...
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