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Questions tagged [demodulation]

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0
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1answer
69 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
52 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 ...
1
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4answers
151 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 ...
1
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0answers
85 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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2answers
87 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 ...
2
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2answers
114 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 ...
2
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0answers
165 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 ...
1
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1answer
202 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 ...
2
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2answers
107 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. ...
0
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1answer
249 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 ...
1
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1answer
45 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
48 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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0answers
86 views

Envelope detector circuit, can I use the signal before it in other parts of the circuit?

So, I'm trying to make a "double" modulation, at time 0 the RF transmissor circuit is modulating his signal in 2.4Ghz GFSK. At time 1 it changes his modulation to OOK 125Khz. On the reception side the ...
0
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1answer
335 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 ...
0
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1answer
169 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
47 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
340 views

Square Law demodulator. How to extract the term \$m^{2}(t)\$?

We are trying to extract the message signal from the AM signal using square law demodulator. In the final expression, \$V_2(t)\$, the term encircled in blue has to be retained, and the others have to ...
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0answers
117 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
245 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 ...
0
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1answer
217 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
843 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
119 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
391 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 ...
0
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1answer
66 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 ...
1
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2answers
125 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
133 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
45 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
77 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 ...
0
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1answer
148 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 ...
1
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1answer
62 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 ...
0
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2answers
580 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 ...
0
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0answers
117 views

sigma delta SNR

As you know, Sigma-Delta Modulator as the core of sigma-delta ADCs defines the total SNR. I am simulating a very simple code for first order delta-sigma modulator. According to text books, the SNR of ...
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2answers
225 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 ...
0
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1answer
547 views

AM Demodulation with Envelope Detector

I have to project an AM demodulator using an Envelope Demodulator. To which kinds of AM (DSB, DSB-SC, VSB, SSD) is it applicable to? Thanks
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0answers
61 views

Sample an AM Demodulated Signal to Bits

Is there a method for automatically sampling and converting an analogue signal into a series of bits? I have an AM capture of a ceiling fan remote as a wave form, and so far I've been manually ...
2
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3answers
1k views

FSK demodulation using DSP

Especifically talking, I need to demodulate a low frequency FSK signal( betwen 120 and 140 kHz ). I already have a circuit of antenna that receive the signal and I already can sample it, but I still ...
0
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1answer
65 views

How does QAM retain the phase of the signals?

QAM is a modulation technique where amplitude modulation is performed for two signals, one sine signal and another cosine signal. Since the signals are out of phase, the information in these signals ...
0
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1answer
77 views

Will a BPSK Demodulator designed for [ 0º , 180º ] symbols work for [ +60º , -60º ] symbols?

I am using an IQ-based digital demodulator circuit IC to receive and decode BPSK signals. It is designed for ordinary BPSK signals, which have [ 0º , 180º ]. However, the signals I am intending to ...
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0answers
203 views

Delta modulation (DM) signals

Trying to understand this circuit. Will this produce a representation similar to example in second image (if U_inf is the sine wave "original") ? Assuming that, I expect U_DM to look like the "...
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2answers
869 views

AM Demodulation of Square wave

Good day Guys, I am working on an AM Modulator and Demodulator circuit using the diode method. My modulation signal is a 10kHz Square Wave and I have a carrier frequency of 850 kHz. My modulation ...
1
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2answers
133 views

Modulation signal getting distored when connecting demodulator

Good day Guys, I have a question regarding output signals of a specific stage getting distorted when connecting the next stage. In my scenario, I am working on an AM modulator and demodulator of a ...
1
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3answers
1k views

Envelope/Peak Detector

I am working on a project in which we are trying to design and build an ultrasonic thickness gauge that will calculate the thickness of a given part based on the time difference between sending a ...
12
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2answers
7k views

Understanding the relationship between LoRa chips, chirps, symbols and bits

I'm trying to understand the actual relationship between LoRa chips, "chirps", symbols and bits. I don't mean just the equations that relate the various rates, but actually how these things relate ...
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0answers
69 views

How could I interpret these-2 YUV modulated picture given in wikipedia? is it correct simulation? or something I'm missing?

While reading the wikipedia article on YUV color modulation (which is used in PAL color tv receivers); I visited this diagram: (Wikimedia); (and according to the image description there; i.e. "...
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0answers
405 views

How to analyze RFID tag/reader communication using Oscilloscope?

I'm trying to analyze the transmission of a 125 kHz RFID reader using nothing but an oscilloscope and am wondering the best way to go about it. I know this is possible from this post from Cornell....
3
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1answer
335 views

Problem in FSK demodulation

I have a FSK modulated signal of binary data. This I am trying to recover using PLL. The mark and space frequencies are in the range of 1.5MHz to 7MHz. I am struggling because, the PLL output is not ...
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5answers
6k views

Why, where and how we use envelope detector in AM demodulation?

I have studied AM modulation and demodulation. But i can't understand the purpose of envelope detector in demodulation. So my question is: Why, where and how we use envelope detector in AM modulation?
1
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1answer
232 views

Mixing two square waves and isolating intermodulation component

I currently have two square wave signals at f1 and f2 (f1 >> f2) that serve as reference signals to two separate lock-in amplifiers that are subsequently connected in cascade to extract the component ...
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6answers
860 views

Visible Light Communication Signal Transmission

Im working on a VLC project where Ill need to transmit encoded data through an LED using an Arduino board to a photodiode receiver that somehow demodulates the signal and extracts the data. Im looking ...
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0answers
130 views

Demodulation wave by smartphone from Jack 3.5

According to post of Jim Dearden I assembled a voltage to frequency converter. The output is transferred via jack 3.5 microphone input to smartphone. From LM331 I am getting square wave with no 50% ...