Generic term for coding information onto another carrier signal

learn more… | top users | synonyms (1)

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1answer
23 views

How to fix a frequency shifted audio part of an RF signal?

I tried to connect an old Japanese (NTSC, System M) video gaming system (an original Famicom, HVC-001) to a rather modern multisystem LCD TV-set (Sharp LC-43CFE5222E). The TV tuner is capable of ...
2
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2answers
53 views

Analog circuit for multiplying in the frequency domain [duplicate]

I have an idea I want to experiment with - doing boolean logic with analog (OFDM) signals. Each frequency component represents a different 'bit'. A key factor is performing the AND operation. I would ...
0
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1answer
38 views

Amplitude modulation and heterodyning [on hold]

I can't seem to find a difference between the two, can someone please explain if there is any? thank you
2
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0answers
46 views

Comparison between FMCW radar modulation techniques

In designing a Frequency modulated continuous wave (FMCW) radar system for target detection, there is a possibility of choosing the modulation technique amongst triangle or saw-tooth modulation. What ...
0
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0answers
40 views

Phototransistor modulation and 50Hz interference

I've got an LED being modulated at 1kHz. This then points towards a phototransistor (LPT80A) which is wired up in a common emitter configuration with a collector resistor of 1k. The output of this ...
1
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1answer
37 views

Is Turbo decoding modulation dependent?

I want to use the BER result of a turbo coded system from an article, but my system is not BPSK (and the article has discussed just the BPSK case). Now I wonder is Turbo decoder, modulation dependent? ...
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0answers
36 views

complex signals and modulated signals [duplicate]

I'm taking an intro electrical engineering class in an online university and have come across something that is confusing, at least to me, since the text we are using does not go into detail about ...
0
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1answer
17 views

Controlling initial phase of carrier during modulation?

During the process of modulation, any of the three parameters, viz \$\ A_c\$ , \$ω_c\$ and φ, of the carrier wave can be controlled by the message signal where φ is the initial phase. How is it ...
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3answers
129 views

Operation of LC circuit in Frequency Modulation with simulation and linking it to the basic principle of frequency modulation [duplicate]

Can somebody help how message signal (words spoken near microphone) is modulated using LC circuit and how lc circuit oscillates at particular frequency by applying dc voltage. In the below circuit ...
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1answer
416 views

Why FM stereo uses DSB-SC instead of VSB?

Using vestigial sideband instead of double sideband supressed carrier could make the baseband stereo signal more compact. Would there be any other benefits or downsides of employing VSB?
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2answers
85 views

Why doesn't Class C modulator operate in saturation?

The following circuit is a class C (actually class B) amplifier used in AM modulator in my previous question. According to the textbooks, the transistor is driven into saturation in this class. A ...
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1answer
99 views

Analysis of Class C AM modulator

The following schematic is a class C AM modulator without use of any transformers I've just changed the parameters in spice to get a correct modulation. however I want to find the theoretical value ...
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1answer
67 views

Help identifying modulation scheme

I'm trying to identify the following modulation scheme being used to transmit a infrared code. It looks like manchester, but there's some gaps where there's no transitions. The code being ...
0
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1answer
63 views

Gray coding for 8-triangular signal constellation

I'm trying to find the gray coding for the 8-triangular signal constellation below, but no matter what I try, one of the neighbors always has 2 bits differing. For example, two of the neighbors for ...
0
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2answers
105 views

How to modulate a LED to send data and recieve with a photodiode

What is the concept of modulating a light source (white led, IR led, etc) to send data and then demodulating it with a photodiode back into data? I am wanting to experiment with trying to use ...
1
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1answer
59 views

Retrofit a Hi-Fi remote with a RF 433 MHz module

In the past I used a remote for a AIWA Hi-Fi to control a AVR processor and circuit I custom made. I used an infrared receiver from Vishay (tuned on the 38 kHz) to demodulate the signal, then fed to ...
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3answers
78 views

Is there a Binary Frequency Shift Keying (BFSK) with only one sine tone?

I mean a modulation technique where a binary one is represented by a sine wave with some frequency F and a binary zero is represented by an absence of any signal, or vice versa. Does it have a "right ...
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0answers
28 views

Compressed single-sideband modulation?

I've had an idea for a new form of SSB modulation, using half-angle formulas as a basis for compressing the sideband of a SSB voice transmission. However, this idea seems so simple that I feel it must ...
1
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1answer
49 views

Bessel Differential Equation and Angle Modulation

I'm trying to undestand the role of the Bessel differential equation in calculating the side bands of a phase modulated signal. I started out with the textbook example $$u_{PM} = cos(w_C \cdot t + ...
0
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1answer
52 views

QAM demodulation , hard vs soft if there is any

I am trying to find the answer to , what types of demodulation methods are exists. Each of my searches results with different names, but converging to one metric , which is finding the closest symbol ...
0
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1answer
75 views

Transmitting data over inductive charging coils (or boosting RFID/NFC power supply)

I know that data can be sent over power lines through various different types of modulation - that is as far as my knowledge ends. I have a small D.I.Y. project (a board game) that requires some form ...
2
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1answer
117 views

Definition of \$\mu\$

I have a question as follows. This is not a homework question I just need to clarify my doubt on how this modulation index is defined. Suppose a 2kHz audio tone having 2V amplitude is to be amplitude ...
3
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1answer
87 views

Why is the modulating shape appear in both sides of the carrier signal in AM?

It's about Amplitude Modulation. Can anyone tell me why is this signal wave or modulating waveform shape appears in both sides of the carrier sine wave? Why not in one side only? $$x_c(t) = A_c[1 + ...
3
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3answers
124 views

Radar Snr improvement

I have a simple radar module (k-band) that is capable of fm modulation and it provides both I and Q as baseband outputs. I like to extend the measurement range of this module by just signal processing ...
0
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1answer
130 views

How is FM modulation is achieved using a single BJT

I want to understand how this circuit achieve frequency modulation. The BJT is a 2N3904. I found that millers effect comes into play and varies the frequency of the tank circuit about a center ...
3
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2answers
332 views

Does a carrier wave need to be sinusoidal?

I am trying to AM modulate a song and I have an idea of how I am going to do it, but I need a carrier wave to start with and I've been having trouble creating one with a ceramic resonator because I ...
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1answer
136 views

Carrier generation at receiver in DSB-SC modulation?

As shown in fig., In this scheme input signal is square and passed through a narrow(high Q) bandpass filter tuned to \$ w_c\$.Finally the ouput comes to be a sinusoid of frequency \$ w_c\$. But to ...
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1answer
55 views

Frequency Modulated Continuous Wave Radar: Basic Confusion

I was reading about Frequency modulated Continuous wave radar but still struggling to understand it. I have a few questions in the slide above. The blue line in the graph represents the transmitted ...
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1answer
90 views

How does modulation technique affect channel capacity?

Shannon's channel capacity formula does not consider modulation techniques. How then does LTE achieve high data rate using advanced modulation techniques? P.S: I am novice in RF and signal ...
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0answers
64 views

optical wireless link short range high throughput

I am student and I want to realize a wireless optical link in order to have a throughput of 100Mbps max and the distance between the emitter and the receiver is about few centimeters. I have made my ...
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2answers
106 views

24GHz Mixer - How to shift the frequency of a 24GHz(100MHz bandwidth) signal by +-4kHz

Why do I want this? When a 24GHz radar signal hits an object that has a relative velocity, the frequency of the signal will shift by a frequency on the order of kilohertz. I want to create this ...
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1answer
69 views

Matlab: Channel coding and modulation [closed]

This is a beginner level question on understanding modulation and channel coding. The confusion arises when I am trying to implement the concepts. Let's say I have the information bits as ...
1
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1answer
48 views

Find Power Spectral Density of given signal

I am given a question with very brief notes to study from. The question is this: Now I was wondering, are the following part of the notes relevant at all: Is this the appropriate method to solve ...
2
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5answers
478 views

Why can a single sine wave signal be used to send digital data but a composite signal is needed to send human talk,etc.?

I can understand the following text (Data Communications and Networking: 4th Edition, Berhouz Forouzan, Ch.5, page 179) which says that a property of a single sine wave carrier signal (phase, ...
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votes
3answers
685 views

FM transmitter design?

I stumbled across a relatively simple FM radio transmitter online. Credit: makezine.com I wanted to understand how it works (it is called "super simple" on the website), but several hours I have ...
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0answers
59 views

Speaker designed for ultrasound operation

I've created a transmission protocol in order to transmit information bits between a PC speaker and a smartphone, or between 2 smartphones using ultrasounds. I've implemented a QFSK system which uses ...
0
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0answers
131 views

Phase reversal in over modulated AM wave and DSB-SC wave

I am new to communication systems and I only know that in an over modulated AM wave, the envelope is distorted and can't be detected properly. But is there any phase reversal in over modulated AM ...
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1answer
140 views

What's the advantage of PAM modulation over QAM?

What are the main advantages of PAM (Pulse amplitude modulation) modulation over QAM ? Ethernet is using PAM for 1000BASET and 10GBASET, but any other high speed links use QAM like DOCSIS, ADSL/VDSL ...
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0answers
64 views

internal circuitry of LM1596/1496 perform modulation

The following is the inner circuitry of LM1596 which is a modulator and a demodulator: I wanted to get an abstract idea as to how this circuit actually works and performs de/modulation... I have a ...
2
votes
2answers
81 views

How are the original signal and the AM signal related?

Use the TIMS “Variable DC” module to generate a 1V DC signal. Use the “Adder” module to add this DC signal to the message signal generated in task 1 (this will produce the ...
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4answers
3k views

If an FM signal has different frequencies, how does the radio receive the signal in a fixed frequency?

If an FM signal has different frequencies according to the modulation, how does the radio receive the signal in a fixed frequency like 103.2 MHz?
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1answer
64 views

About the combination of two signals with capacitors

Here is a link of an article I've been reading. http://www.analoguehaven.com/moog/thereminblack/hotrod.pdf In page 4 there is a circuit schematic. Notice there is a part called variable pitch ...
2
votes
1answer
97 views

Orthogonal Frequency Division Multiplexing (OFDM)

I am not a professional but I'm trying to figure out how OFDM works. It is clear to me that OFDM works with closely spaced subcarriers with orthogonal frequency. Each subcarrier gets modulated with a ...
1
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1answer
120 views

Spread spectrum

Are Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Sequence (DSSS) modulations? I am confused because I have read that these are also used e.g. with Gaussian Frequency-Shift ...
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2answers
1k views

What is the required bandwidth for QAM modulation?

Why is the allocated bandwith smaller with QAM-16 or 64 compared to e.g. QAM-4? I am not a professional so I'm looking for an intuitive explanation.
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1answer
203 views

Calculating Data rate function of bandwidth and SNR

I plotted BER vs SNR for BPSK modulation in Matlab and I am given bandwidth of channel (bandlimited channel). lets say it is BW1. I would like to find the data rate based on this information. I am ...
1
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1answer
52 views

Channel Coding with Higher modulation

Just had a theoretical question. I'm reading a book on LTE, and I came across an introductory section that talks about using higher modulation with channel coding. I understand that usually using ...
0
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1answer
73 views

Estimate the bandwidth required to transmit 1Mbits/s of data using a modulation scheme which comprises 32 different frequencies and 2 amplitude levels

Estimate the bandwidth required to transmit 1Mbits/s of data using a modulation scheme which comprises 32 different frequencies and 2 amplitude levels Yes, this is a homework question that ive been ...
0
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2answers
79 views

Drive electo-optic modulators with FPGA

I am currently using an FPGA (Virtex II NI RIO7831R) to generate the clock for a pulse generator used to drive a Linbo3 optical phase modulator. ...
0
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1answer
40 views

How to identify when a pulsed rf supply is active

I have a signal that consists of a 13MHz RF signal inside a pulse envelope (around 100ms on, 300ms off). I want to convert this to a 0-5V pulse that will just tell me when the primary RF signal is ...