Questions tagged [modulation]
Generic term for coding information onto a carrier signal.
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How can I design a beta modulator block
I am simulating a block beta modulator, but the problem is to switch uses in that block. What component do I have to use in place of U3? I did not find this type of any component in LTspice library ...
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Understanding an op amp modulator circuit
I'm trying to understand an op amp modulator circuit I came across in a book. The circuit uses switches. According to the book, switches S1 and S4 are on during the positive half cycle of the carrier ...
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Delta Sigma modulation proof of average
It can easily be proven that an ideal analogue delta sigma modulator shapes the quantisation noise, as explained for example in this AD note under EQ 3: https://www.analog.com/media/en/training-...
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QPSK Modulation towards DAC
Modern DACs are able to accept 2 digital values (representing I and Q), multiply them internally by a Sine and Cosine waveforms and combining the result to form the output signal.
When dealing with ...
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How to convert low voltage digital signal (0-3.3V) to high power current signal 15-40W ranging from 1kHz to 1MHz?
I need to convert a digital signal generated from a microcontroller GPIO (0-3.3V) to a high-power (15-40W) current signal to drive an LED chip for illuminance, where the signal frequency can range ...
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Can Bandwidth be Traded Off with SNR in Analog Modulation?
With typical linear digital modulation schemes, we can, for a given bit rate, make a trade-off between modulation bandwidth and modulation order (effectively, how close the constellation points are).
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Designing loop filter for frequency-modulated PLL
I'm designing a PLL circuit to stabilize a ~200MHz VCO against temperature-induced frequency drift. However, I need to be able to occasionally (~few times/sec) send a short pulse (~few μs) to modulate ...
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Testing an IC : IO PAD experiences 2nd-order ramping effect
The IO is a regular PMOS-PULL-up and NMOS-PULL-dn IO with series resistors on pull-up and pull-dn branches. The IO is input an clock signal around 50MHz and it experiences an approximately 2nd-order ...
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How to determine Phase Angle of 16-QAM
I am trying to figure out how the angles for the following input are obtained. For example, why is 0100 -105 degrees and not 45 degrees? Is there a specific method or do we estimate what the angle ...
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How does modulation affect RF power measurement?
I'm working on a ground station for cubesats and I have a question about the protection circuitry I'm designing. The amplifier I'm using is the 1094 amplifier from empowerrf which can be seen here.
...
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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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Differential amplifier and modulation
I conncected this differential amplifier circuit:
The input V1 was 50mV,5kHZ and V2 was grounded
When I measured the output VO1, the oscilloscope gave me a weird signal that was not sinusoidal but ...
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What is the tranfer function of Electroabsorption Modulators?
Can anyone give me a reference that I may find a closed-form formula for the output electric field (not power) in terms of the input small-signal electrical waveform (not input power) of an ...
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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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Why does the frequency deviation of a FM wave have different definitions?
Source 1 defines the modulation index in the expression for FM as follows:
As per the expression for frequency modulated wave, isn't the frequency deviation same as Modulation index 'M'?
"The ...
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CC1125 tramsmit data from the nanosatellite to ground station
does the chip cc1125 can transmit data between nanosatellites to ground stations the distance between them is up to 400km with band frequency UHF from uplink and vhf of the downlink.
If yes can use ...
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How to improve the sine wave coming in to reduce the power bill?
Can the sine wave from the electricity that comes from the electric company be modified to make your appliances run more efficiently in turn saving electricity cost? How?
Related: How to make pure ...
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LoRa - Frequency Shift Chirp Modulation - chips in a symbol
I am trying to create a form of FSCM (frequency shift chirp modulation) based on LoRa principle just to learn from it and to obtain a deeper understanding.
What I do not get:
why is (or must be?) the ...
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VHDL: Testbench for ASK modulator
I've been trying to learn VHDL recently and came across the following tutorial for an ASK modulator: https://surf-vhdl.com/implement-digital-ask-modulator-vhdl/
I tried writing a testbench for this ...
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Where and how are the carrier and message signal multiplied in this circuit?
I have this circuit diagram of an AM modulator and I am trying to understand what is going on.
I know that the c(t) is taken from the collector of transistor Q1 and the multiplication of signals : m(t)...
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Signal modulation with VNA
I want to apply a 1 V, 1 MHz signal to my DUT (coaxial waveguide) while sweeping the frequency from 300 kHz to 6 GHz by the VNA.
Right now, I applied the signal by the signal generator to the bias tee ...
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FSK Modulation in Python
I am currently writing a script that uses I/Q data to do FSK modulation.
My question is about the FFT plot. I expected to have a peak at 1Hz and 2Hz which are the frequencies that represent binary 0 ...
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How to amplify signal enough to make a Langevin transducer vibrate?
I'm a little out of my zone of mechanical engineering here, so I'll need your help.
Up to date, I got the right frequency (40 kHz modulated for a 200 Hz low frequency) coming out of my function ...
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MOSFET driver circuit for wireless charger improvements
I'm designing a circuit for power wireless charge.
The final application is a remote controller which needs to be charged and programmed with no cables.
The circuit i designed, charge the battery of ...
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FET AM modulator
I have been meddling with a FET-based AM modulator. I implemented a basic circuit as attached here along with its output. Is the output as it should be? If not, what am I doing wrong, and how can I ...
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Converting an FM square wave into an FM waveform that is sinusoidal
How could I convert a frequency modulated square wave, like from the timer 555 output, into a frequency modulated sine wave?
P.S. I added here the image of the circuit schematic for a more complete ...
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Op-amp chopping principle in frequency domain to reduce offset voltage
I am trying to understang the chopping principle used in op-amps with help of this document (page 19 - 20.)
I understand that switch S1 (aka modulator M1) causes modulation with 1/2 duty cycle and it ...
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I want to divide a pulse in time axis and create more pulses
I need help with my project. I want to split a pulse on the timeline. I want to take the signal and divide it by 58 μs. Actually the time of the output signal is not important. I just need to generate ...
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How are discontinuities in quadrature modulated signal QAM physically produced?
In quadrature modulated signals, for instance:
I am unclear how the "discontinuities" in the waveform at the junction of each data point can be physically produced?
Taking a speaker as an ...
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Increase input frequency circuit
Referring to this website, this circuit tries to replicate the waveform of the input voltage and turn it into a high frequency, I tried to simulate the circuit in LTspice, but the output is weird. May ...
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Modulating a high-frequency signal to get rid of an undesired low-frequency component
So when I ask my function generator for 2 MHz, it gives me that with a 19 Hz oscillation. For my application this low-frequency signal is very problematic. I've tried high passing it which does close ...
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Received QAM symbol demodulation
We're using 64QAM with unit average power and gray encoding.
The modulated representation corresponding to symbols :
1 => -0.923 + 0.659i
2 => -0.923 + 0.132i
.
.
45 => 0.659 -
0.659i
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.
...
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How is Pulse Density Module (PDM) signal driven?
I am confused between Pulse Width Modulation (PWM) and Pulse Density Modulation (PDM).
From my understanding, both are used to transmit a digital signal into an analogue domain. It is basically doing ...
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How to measure the input impedance of a laser diode/LED using a VNA?
It would be nice to have some advice on an issue I'm having with a laser diode. I have a DFB laser diode that has no kind of series resistor connected to it in the package. I want to make a driver for ...
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Condition for multi tone AM for proper envelope detection
Given a multi-tone amplitude modulated wave as follows :
s(t) = Ac[1+2kasin(w1) + kasin(w2)] cos(wct)
where wc is the carrier frequency and w1 and w2 are the modulating frequency components. My ...
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How does this modulation cause sidebands?
The following figure is an excerpt from this paper: Input Differential-Mode EMI of CRM BoostPFC Converter by Fei Yang.
Q#1 (first highlighted sentence): How does the modulation line frequency cause ...
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How do I determine the acceptable delay spread in an analog FM simulcast LMR system?
I'm using a commercial propagation analysis software to analyze a legacy VHF simulcast Land Mobile Radio (LMR) system. I'm trying to analyze the parameter "Delay Spread". The software ...
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Transmitting an RS232 Signal over Wireless/RF. Can this be achieved? [closed]
I have an idea I am trying to implement and I want to know if this is possible and feasible.
I have a Barcode Scanner device that gets connected to a PC with a DB9 COM port. Using this connection and ...
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Mixing current in Gilbert cell
I'm currently breaking my head over this Gilbert cell:
I understand the workings of this circuit, that is not the issue I'm having.
What I do not understand is, when looking at the current waveforms:
...
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Ethernet: uses baseband line coding?
Is ethernet baseband line coded without the presence of multiple carrier frequencies signaling over the line? For instance, cable TV uses multiple carrier frequencies each representing a different ...
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AM modulation: bandwidth of sidebands? [duplicate]
I’m trying to understand how an audio signal is represented with electrical signals and modulated. I and have questions which follow. Wikipedia says
An audio signal is a representation of sound, ...
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How to compute data rate I can reach with my design?
I implemented a modulator for a transmitter, which sends baseband modulated signal.
The transmitter has the following parameters:
datarate : 520 Ksps (min), 64,44 Msps (max)
Bandwidth: BW = 56 MHz (...
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Signal Modulation with Carrier Wave?
Image B shows the frequency of an FM signal is changing, yet I know a single broadcast station on FM is specific to a single frequency. Is the pictured FM signal again modulated with another fixed ...
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Carrier Waves, modulation over RF vs on wire
I’m reading about carrier waves and signal modulation. It appears signaling has differences over RF vs wire. RF requires accelerating charges to induce a voltage change at the receiver. Straight wire ...
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Please help to verify my explanation for the amplitude and help to explain why the amplitude diminishes over time
I have the circuit below which consists of a series resistor followed by a parallel LC circuit:
It produces this output waveform:
From the simulation, I know the waveform has a frequency of 10Khz ...
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Why is the op-amp able to eliminate negative voltage?
I have a circuit with the attached waveform. Can someone please explain why the 2nd op-amp (middle) is able to eliminate the negative voltage? By reasoning and analysing the circuit I can see that the ...
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How would a modulated and demodulated signal differ in FM and PM? Simulink Simulation
I am trying to observe the differences of phase and frequency modulation. On the figure below, the left scope shows a frequency modulation and demodulation whereas the right scope shows a phase ...
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What is the function of frequency resolution in multisim
In this circuit, noticed if the frequency is set to be the same as source frequency, the display will show a constant peak. The modulation index is 0.6.
However, if the resolution frequency is set to ...
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Downconversion Intermodulation Frequencies - Where do they come from?
I recently came across this video which discusses the downconversion of a signal (referred to as IN) to an Intermediate Frequency (IF) using a Local Oscillator (LO). I'm assuming that all of these ...
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How is a GPS receiver able to calculate SNR?
I know that there is a certain relation between bit error rate and SNR for every modulation scheme. But i wonder how a GPS receiver can measure bit error rate and how it able to calculate SNR (I could ...
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