Questions tagged [demodulation]

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1answer
114 views

Can someone explain how this Ratio detector circuit works?

I understand how a Foster Seeley discriminator works, but in this Ratio detector, which is a modified version of the former, I don't understand the purpose of having three transformer windings, or ...
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0answers
18 views

How to perform multiplication at the time series level for chirp signals

As the title said: How to perform multiplication at the time series level for chirp signals? In LoRa modulation, when received a chirp modulated signal, to demodulate it, LoRa will first multiple the ...
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1answer
63 views

Envelope detector for AM signals

How or what are the constraints for deciding factors of envelope detector for AM As far as I know that charging time of capacitor should be below 20T where T is periodic time of carrier and ...
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0answers
23 views

Foster - Seeley FM Demodulator Explanation

Consider this Foster Seeley Demodulator If I have correctly understood, its basic working principle is the fact that at the secondary coils (L2) of the Balun there will be two signals equal and ...
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1answer
39 views

What is the minimum sampling rate for QPSK or what is the bandwidth of QPSK signal?

Consider we have created a QPSK signal with a carrier frequency 100kHz. Before applying matched filter or demodulation we need to take sampls from the received signal. So what is the minimum sampling ...
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1answer
29 views

What is a reference oscillator which is used in Costas receiver?

A Costas receiver has a voltage-controlled oscillator, which is sometimes referred to as reference oscillator. What is the input and output of this reference oscillator?
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1answer
65 views

FSK demodulation with LM565

On the Internet I found FSK demodulation connection diagram with LM565 . And I'm trying to connect up it in Qucs. At the output of the whole schema I get unclear result. In my previous topic we were ...
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1answer
55 views

FM Demodulation

I'm using a demodulation fm circuit in multisim. it takes 1 minute on the oscilloscope to complete a full waveform, and every waveform the amplitude is decreasing. I want to know why is the amplitude ...
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0answers
56 views

How does a rectifier demodulate radio information and why does its capacitance matter?

I read in a forum “A point contact diode like OA79 should be used for the demodulation of AM. This diode is a signal diode and is having a low junction capacitance because of its special construction. ...
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1answer
96 views

Synchronous demodulation with single supply op-amps

I am looking at the following article from Analog Devices: Use Synchronous Detection to Make Precision, Low Level Measurements, and I'm wondering if there is a way to build the following demodulator ...
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2answers
33 views

Proper term for waveform correction — demodulation or undistortion

I have a measured a periodic signal waveform \$v(t)\$ that can be modeled as: \$v(t) = f(\phi) A \sin(2\pi ft + \psi)\$ where \$A\$ is a constant amplitude, \$f\$ is signal frequency, \$t\$ is time ...
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0answers
54 views

ASK demodulator not working as expected

I have implemented an ASK modulator and demodulator pair. The modulator works fine, but the demodulator is giving a vague output. Below is the image of the whole circuit and the simulation output. ...
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1answer
22 views

prevent receiver components from interfering with output of modulator

I am working on an ASK modulator and de-modulator. The modulator works fine (thanks to great folks at SE). However when I try to pass the modulator output to the input terminal of the receiver, the ...
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0answers
37 views

In need of help to figure out why my 4046. demodulator circuit simulation is giving me errors

I’m currently doing a project on FM modulation and demodulation and on my proteus simulation I just can’t figure out how to do away with the two errors I keep getting. Here are the images of my ...
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0answers
28 views

PLL with two input frequency within lock range for FM demodulation

I have current output from a photodiode which I believe containing at least two distinct frequencies that is not too far apart from the lock range of a PLL which taking this current as the input ...
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0answers
85 views

Demodulation of a 38 kHz IR PWM signal

I want to learn how to demodulate a 38 kHz IR PWM signal.(Such as that transmitted by a TV Remote Control) I know it can be demodulated easily using a TSOP1738 IR receiver. I realize that the ...
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1answer
38 views

Source generator for Satellite Tuner input

I need to design a source generator for a TV factory. They want to automatize the functional tests by applying a test module to the TV's at the end of the production line. All the peripherals of the ...
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1answer
118 views

In this Foster Seeley discriminator, what is the purpose of capacitor C3?

I understand the whole circuit, except for the use of capacitor 3. What's its purpose in here?
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0answers
74 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 ...
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0answers
127 views

Keyfob decode using GNU Radio Companion

Found this project to decode Hella Keyfobs https://github.com/bastibl/gr-keyfob Try to decode mine, but somehow the signal is way different from the one from the above Repo. From the repo: Mine: ...
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1answer
118 views

Can a speaker be driven by a DC signal?

I’ve always been under the impression that speakers require an AC signal. The reason being that positive and negative current are required for the electromagnet to properly vibrate the diaphragm. ...
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2answers
57 views

Geometric representation of GMSK signal

Can anyone provide me the geometric representation of GMSK signal? Also, am I correct in saying that bit energy of GMSK is same as its symbol energy since MSK is a binary modulation scheme with only ...
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4answers
208 views

Is there a way to extract out just the Carrier signal from an AM signal?

I have a AM signal with 13.56MHz carrier and 125KHz data signal. I was wondering if there is a way to extract out just the pure carrier signal out of this AM signal. I was thinking about passing it ...
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0answers
107 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 ...
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3answers
178 views

High frequency AM demodulation

I'm building an light communication device(pretty much lifi) using AM and am mostly done with every part except for demodulating the signal. The signal looks like with a 1.8432MHz carrier wave(serial ...
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2answers
264 views

Select Phase Detector Cutoff Frequency? Phase Locked Loop FM Demodulation

I'm studying a Phase Locked Loop used for FM demodulation, obviously a phase detector is used in the system. A basic implementation of a phase detector is a multiplier followed by a lowpass filter. I ...
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0answers
297 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 ...
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1answer
520 views

Choosing a RF Detector Circuit for my Sweep Generator

My newly acquired sweep generator (wobbulator) doesn't have an inbuilt RF detector circuit unlike some others (some Wavetek models). So, I decided to build one. I was quite surprised at how many ...
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2answers
129 views

What kind of component was used in this demodulation circuit?

I was trying to gather components as well as some desoldering experience from an old television tuner when I found those little fellows: They were sitting next to an IC with the Code TDA 6160-2X. ...
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1answer
368 views

Best mixer for quadrature FM demodulator

I need to demodulate an FM signal and I want to use a quadrature demodulator for this. The signal is 16±0.15 MHz, 3.3V output from CMOS oscillator. I know that Gilbert cell mixers are most commonly ...
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1answer
92 views

Demodulator with Schottky diodes

I was wondering how this demodulator works. The input voltage is on the left at C2 and the output voltage is on the right before C3. What is clear: C2 filters out low frequencies at the input, C3 ...
1
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1answer
59 views

Modulated IR for optical transmission of encoder data (TSOP 4840)

Some background: I am a mechatronics engineer and I have just recently started my first job out of university as an electrical engineer. I feel a little out of my depth but I wasn't going to turn the ...
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1answer
903 views

Interpreting IQ Data (as hex) from an RTL-SDR/Hack-RF

I am wondering if someone can shed some light on how to meaningfully interpret I/Q data that is produced from an RTl-SDR dongle (RTL2832U) using the Osmocom RTL-SDR library. I have used I/Q data ...
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1answer
261 views

Choosing the best FM demodulation technique

I have an FM signal: 200 mVpp, 11.5 MHz carrier, max deviation - 500 kHz, modulating signal frequency range is 40-10000 Hz. And I need to demodulate it with highest SNR possible. The circuit has to ...
2
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1answer
53 views

Vestigial Side Band Demodulation: Which components are to be retained and which are to be filtered out?

This article shows the analysis of Vestigial Side Band Suppressed Carrier demodulation. I have understood the mathematical derivation up to eq (1). However, I am unable to understand which components ...
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0answers
129 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 ...
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2answers
417 views

Is it possible to recover an over-modulated waveform?

Is it possible to recover an over-modulated waveform? I have searched the net up and down but I constantly come across the same answer 'It is not possible to fully recover a full AM signal using an ...
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1answer
291 views

Analog Phase Locked Loop Design

I am trying to design a phase locked loop in MATLAB's Simulink. For this, I am following this basic block diagram design: My original message signal is ~12 seconds long, has a bandwidth of ...
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2answers
2k views

Demodulate a AM signal from the carrier using Matlab

So the AM signal has a bandwidth of 5kHz and the carrier signal is 100kHz. I demodulate the AM signal by multiplying it to a sin function (sin(2000000*pi), same frequency with the carrier frequency). ...
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2answers
154 views

Efficiency of FIR filter in verilog language

Implementing a 4-tap FIR unity coefficients, is this code efficient in power and area ? ...
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2answers
534 views

pwm audio signal with low pass filter

I am trying to demodulate my PWM by using a low pass filter shown(the inductor of 6uH and capacitor of 10uF forms my low pass filter). The PWM was created using a triangular waveform produced by XFG1 ...
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1answer
70 views

Recover IQ samples from signal [closed]

I have a data acquisition device that provides me with an array of integers that represents a modulated signal (let's say QAM16). I would like to recover the I and Q samples from the raw time-domain ...
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2answers
170 views

Low frequency receiving scheme/circuit

I was going through the documentation of TPMS sensor FXTH87 and I am trying to understand better how the low frequency receiver works. Here is a scheeme of it : I understand that the incomming signal ...
1
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1answer
142 views

How to amplify the envelope of a signal at envelope demodulator?

I have a wave with ~ <10% modulation. Is there any way to amplify the envelope of a signal at the envelope demodulator end? You can barely make out the envelope in the image below but I think I ...
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2answers
47 views

OFDM demodulation time

How much time does it take to demodulate one OFDM symbol? In 802.11a standard the Symbol Interval Time is 4us. Does this mean that each symbol is demodulated within this period or there is pipelining ...
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0answers
98 views

Output of a PSD fed a square wave

This is the question given in one of my papers. Input is a square wave, if phase shift was zero it would be just flat positive line, if phase is pi it would be flat negative line. Here the phase ...
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1answer
168 views

Front-End Selection for digital FM Demodulator [closed]

Assume that I want to determine the specifications of an analog front-end to build a digital FM demodulator to listen to radio broadcast stations, how would I start? The broadcast frequencies of ...
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1answer
67 views

Duty Cycle Demodulation Distortion Correction

I'm trying to come up with a system which will reliably convert an arbitrary input to a PWM signal, and then back again. The comparison signal is a 50kHz sine wave, and the result is fed through a ...
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2answers
719 views

Balanced demodulator [closed]

I came upon this expression "Balanced demodulator" while reading about signal modulation, but didn't find anything that explain what is a balanced demodulator, can anyone explain this or give me any ...
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2answers
241 views

Techniques for digitally copying video laserdiscs

I’m attempting to design a system that can back-up the information stored on a video laserdisc by interpreting the RF signal generated by the photodiodes within the optical deck of the player. The RF ...