Generic term for coding information onto another carrier signal

learn more… | top users | synonyms (1)

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3answers
82 views

An alternative way to make a VCO?

from what I am able to understand, a voltage controlled oscillator is "controlled by a voltage" when this voltage is applied to vary the value of the tank circuit: eg this could happen by applying ...
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2answers
30 views

How to calculate the RMS of an AC PWM?

I am looking at a servo, which is driven by PWM. The PWM signal itself modulates NOT DC but a sine AC, so when Throttle is set to 100%, I can see a rather nicely drawn sine wave. But when Throttle is ...
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1answer
22 views

Amplitude modulation transmission distortion

I need to clarify a question. Let's say that in a wire I carry a current modulated in time so that it is an amplitude modulation of a sinusoidal carrier with a modulating sinusoidal wave. In frequency ...
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0answers
15 views

Composite Video over Fiber at DWDM frequency [closed]

I am trying to set up an analog test system to demo the capability to transmit an analog signal over fiber at a specific wavelength (in DWDM ITU channel range). I would like to grab a video output ...
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5answers
72 views

Does increasing the amplitude of a signal also increase the data rate?

I face an ambiguity when considering the carrier frequency, signal frequency, bandwidth and data rate. When I consider the Shannon formula, I wonder if increasing the transmission power also means ...
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1answer
11 views

A question related to “quadrature carrier multiplexing”

While studying 'Qaudrature carrier multiplexing', I came across these statements in my text material: "Precisely varying the phase of a high-frequency carrier sine wave in a hardware circuit ...
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1answer
52 views

Working of ring modulator

I am having trouble understanding how this ring modulator works i.e. how it multiplies the input & carrier to give us appropriate output? Any help or guide will bedeeply appreciated. Reference - ...
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1answer
51 views

In Analog to Analog conversion , why we multiply instead of adding?

When we use AM i.e Amplitude Modulation , we multiply the source signal with the carrier , My Question is , why don't we add the signals ? it would be easier to modulate and demodulate I think.
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0answers
17 views

How to prove FM is superior to PM for tone modulation for a given signal?

How to verify that for tone modulation FM is superior to PM for the signal x(t) where \$ x(t)= 8cos(\omega_0 t) + cos(5\omega_0 t) \$?
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1answer
57 views

Emulating greyscale on a 1-bit LCD

I have an LCD (the DOG-M 102x64, with a uc1701 controller) that I am driving (over SPI, but that's somewhat irrelevant) from an AVR (ATMega16 @ 8 MHz) - all in all, a fairly low spec'd screen with a ...
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1answer
52 views

How to shift signal to baseband using local oscillator frequency?

If the input to a demodulator is a signal having the spectrum shown below, how would I figure out what local oscillator frequency is required to shift the signal to baseband? Is there a formula for ...
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0answers
10 views

MU-LAW COMPANDER for a 10-bit Quantzer … ? how many level will be needed to represent the lowest 30% of the signal for U=0 and U=10

for a 10-bit Quantzer how many level will be needed to represent the lowest 30% of the signal for U=0 and U=10 ? I know it it is u=0(simply no compression) so # of level = 0.3(2^10) which is = 307.2 ...
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2answers
62 views

Space vector PWM signals

I have done few BLDC motor controllers with trapezoidal modulation and they work fine. Now i'm trying to build another one with space vector modulation but as it doesn't work well i'm getting more and ...
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1answer
40 views

Can I hard wire an IR remote directly into the receiver?

I have a IR remote control and a clock (which it is designed to control.) I would like to remove the IR LED from the remote and the sensor from the clock, and run a wire between the two (so the clock ...
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1answer
101 views

38 kHz signal arduino demodulation

I need to demodulate signal with frequency 38 kHz coming from remote controller without IR receiver. I need to demodulate it and as a result get information from it. Is there any examples of similar ...
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0answers
45 views

High voltage, low current switching

I am using a high voltage low power integrated circuit (tracopower). I need to siwtch the output with a square wave signal up to 500 Hz. The problem is high voltage transistors also work with high ...
2
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1answer
83 views

Radar - How to keep IF constant?

A basic block diagram for FMCW radar I will be using, modified MIT radar project: MIT block diagram I My transmit frequency is 2200-2600 MHz, my receive frequency is ~2200-2600. I want my IF ...
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1answer
35 views

Analog modulation trainer

i am making communication trainer as my FYP i am confused on analog communication module .. I have 2 options first one to make different blocks of analog like mixers, filters , amplifiers ,phase ...
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1answer
64 views

Appropriate use of the word “modulated”

I don't use the word "modulated" very much and I would like to make sure I use it correctly. The TSSP77038 IR receiver module is a device that detects infrared light turning on and off quickly at a ...
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0answers
142 views

Implementation of PSK modulation/demodulation

I want to implement a BPSK modulation/demodulation using a microcontroller (Arduino Due). The carrier signal should be at 1-50 MHz and the information rate at 300 KHz. For the sender part I would ...
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0answers
33 views

Implement Automatic Gain control for 16 QAM

How can I implement an automatic gain control for 16 QAM modulation in Matlab preferably without channel estimation (trial and error may be).
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1answer
61 views

Why is there a guard band in ADSL

I recently learned about ADSL and its modulation method DMT. I know the frequency spectrum is split up into a number of orthoganally spaced bins: Voice(PSTN) - Guard Band - Upstream - Downstream ...
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1answer
61 views

FM signal example

Sorry if this question is too basic, but I'm a software engineer student who must study communication systems. I try to represent a FM signal in a graphing calculator, but I don't know why the result ...
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1answer
86 views

Amplitude Modulation Frequency

In am receivers, we detect the modulating signal by using envelope detector. So, the diode rectifies the signal, and the detected signal has doubled frequency than the original. Does this mean we will ...
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0answers
65 views

Minimum Shift Keying (In-phase, Quadrature Components derivation)

In the derivation of the minimum shift keying in-phase and quadrature components in Simon-Haykin Communication Systems 4th ed (p.387-390) we start off with the definition of the signal to be \$\ s(t) ...
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0answers
39 views

Bandwidth of a 1,2kbit GFSK and a 9,6kbit GFSK

I want to calculate the bandwidth of a GFSK modulation. In the task are two bitrates given, 1,2kbit and 9,6kbit, and the CC1200 (from Texas Instruments) transceiver is used for the transmission. I ...
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1answer
91 views

Maximum signal data rate

I have a frequency signal range from 25 Khz to 35 Khz. I know that the the minimum signal sampling to assure reconstruction of the signal from the samples is 70 Khz. Would it be correct to assume ...
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2answers
57 views

Which characteristics of a Radio signal are involved to be selected by radio receiver? [duplicate]

the radio antennas receives millions of signals. how our radio selects the appropriate signal as it's input? which characteristics of the signal are involved for this selection.
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70 views

Amplitude modulation circuit explanation

I am currently doing an amplitude modulation experiment and I am using the following circuit: I need to know the effect of the various components regards to amplitude modulation. And also what is ...
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2answers
608 views

How does the plastic-tube inductor in this wireless transmitter work?

This single layer PCB (solder side shown here) is from an old fan remote: The inductor in the plastic tube is not connected physically to any components; however, the two loops of wire surrounding ...
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1answer
153 views

Power efficiency of SSB-Large carrier

i was studying SSB demodulation and learned that a local carrier is added to the SSB signal to make sure that envelope detection is possible. I came across a problem to find the percentage of power ...
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2answers
47 views

frequency modulation and incoming signal selection

I have some understanding of what frequency modulation entails - it entails "adding" a new frequency to the frequency spectrum of a signal. But how, exactly, is a modulated signal selected in the ...
0
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2answers
154 views

How does this AM Modulator work?

I have been given a question and tasked with identifying the various components. However, this circuit doesn't really seem to make sense to me. Error: RC RE inverted simulate this circuit ...
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0answers
40 views

QAM-modulation-how-data-in-different-frequencies-are-laid-out

Monday 27th October 2014 Q.A.M Animation (URL QAM modulation - how data in different frequencies are laid out?) Can you please explain the two instrument icons at the left hand side of the ...
2
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1answer
192 views

Why it has used BPSK modulation after OFDM?

I am quite new to OFDM modulation. I am reading this from a tutorial. In one of its parts, for showing amplitude variation of the OFDM signals, there is a graph that has used 8 sub-carriers and BPSK ...
2
votes
1answer
70 views

How is CPM Modulation Different from PSK?

Continuous phase modulation has been described to me very similar to wikipedia's definition, which basically indicated that the CPM is different from QPSK, for example, because QPSK abruptly shifts ...
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2answers
118 views

How does an AM-modulated signal sound like in a speaker?

Let us compare two signals: one is a normal sinusoidal signal with single frequency 5khz with 1V amplitude (2V peak-to-peak). The other signal has a carrier frequency of 5khz and 2V peak-to-peak, but ...
2
votes
1answer
72 views

Finding the Power developed by the Nominal Frequency in FM

Question The sinusoidal signal \$f(t) = \cos(2 \pi f_m t)\$ is applied to the input of an FM system. The corresponding modulation signal output for \$f_m = 1kHz\$, is $$Q(t)=100 \cos(2 ...
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0answers
131 views

Finding the bandwith of FM by using Bessel functions with 1% rule

Question A 100-MHz carrier is frequency modulated by a 10-kHz sinusoid so that the peak frequency deviation is 30 Hz. Using Bessel functions with 1% rule, i.e. 40 dB down from the unmodulated ...
2
votes
1answer
162 views

How to get BPSK data from I/Q signal

I am using AD8347(0.8 GHz to 2.7 GHz Direct Conversion Quadrature Demodulator) to demodulate a BPSK modulated carrier wave. There is no intermediate frequency used. By feeding the signal into this ...
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0answers
55 views

Difference between “user” and “layer”

I am new to multiple access communication theory. I read some articles on LDS, and I thought that "layers" is a term used for "users" (In another language I thought that for example when we say "we ...
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2answers
323 views

What happens to a DSB signal if I use an envelope detector instead of Low Pass Filter

What happens to a DSB signal Modulated signal if I use an envelope detector instead of Low Pass Filter ? I am interested in knowing how the output signals vary in case of a envelope detector. I know ...
0
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1answer
72 views

Why is the RC value of a demodulator near the geometric mean of the period of carrier and message signal?

The figure below is a AM demodulator. My instructor told me to chose RC so as to satisfy the following inequality Tc << RC << Tm. Where Tc is the period of the carrier wave and Tm is the ...
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0answers
47 views

Ideal Sampling Rate for LFM Signal

I'm confused on how to set the ideal sampling rate for an LFM pulse. As an example, if I create a pulse with a PRF of \$10^3\$, a sweep bandwidth of \$10^5\$ with a pulsewidth of \$10^{-5}\$. The ...
1
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1answer
65 views

Nyquist Sampling rate

We have \$z(t)=\cos(100πt)\cos^2(500πt)\$ . Find Nyquist sampling rate. Well, I know that \$f_s=2f_{max}\$. My main problem is that I am not entirely sure if I could re-write the above signal as: ...
1
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2answers
55 views

Spreading vector

I am reading an article that is about CDMA. In that article I encountered a term "spreading vetor". I searched some books such as Proakis and Gallager to see what it means. I even surfed internet for ...
0
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1answer
132 views

Carrier Wave in Wired Data Networks

I know this must be trivial for many... Which are the main reasons why line data is not modulated/demodulated in normal enterprise wired networks (in the sense that discrete voltage levels are used)? ...
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1answer
185 views

FM and phase/frequency deviation

I have a small understanding issue here, so I would be very glad if someone could help me a bit! We are given this FM modulated signal to volts; ...
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0answers
68 views

Would my project be affected by lack of a filter?

I have chosen to do a final project, I will be transmitting bits using a wien bridge oscilator, I want a 160 MHZ sine wave and I have chosen values for it. I have chosen the AD8041 op amp because it ...
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1answer
423 views

How can i send bits using a wien bridge oscilator?

so i have a string of bits that my shift register will be outputting one after another, i wanna use a wien bridge to send them into air. if a bit is a "1", i want the wien bridge to send a wave, and ...