Questions tagged [signal-processing]

the analysis, interpretation and manipulation of signals

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31 views

Finding gains from the summing different phases signals

I have four signal which are the same frequency and different phases. It is possible to think S1=1kHz sine,0 degree S2=1kHz sine,30 degree shifted S3=1kHz sine,60 degree shifted S4=1kHz sine,90 degree ...
26 views

Fourier Series of Convolution of Periodic and and Aperiodic Signals?

The impulse response of an LTI system is aperiodic and I pass in a periodic signal. Now I need to find the Fourier series representation of the output. Since Convolution in time domain is ...
185 views

Why does an optical drive use laser light?

Nowadays, lasers are cheap, but back in the day when CDs were first introduced, they were expensive. What is the reason for using a laser instead of a normal light source in optical drives?
44 views

Matlab code to derive the overall difference equation relating two systems

Using Matlab, I am trying to: Get the overall difference equation relating to z[n] to x[n] and check if z[n] = x[n] is a valid solution to the overall difference equation I have two signals given ...
49 views

CDMA basic working principle

I find it hard to find on the internet a simplified explanation of the principle of operation of the CDMA system. Could you give me an example of how it works and how a receiver can correctly identify ...
65 views

Final Value Theorem yielding the wrong result?

C1 has an impedance of 1/0.1s Ohm in S-domain. Its impedance together with R1's is 100/(10s+10) Ohm The transfer function is: $$\frac{V_2}{V_1}=\frac{5}{\frac{100}{10s+10}+5}=\frac{50s+50}{50s+150}$$ ...
47 views

Modulate/demodulate 125khz signal to 433Mhz transmitter module (2.5Ghz carrier)

I am trying to implement a project which consists of two circuits. Circuit A receives a 125khz AM signal and modulates it to 433Mhz CC1101 which then uses 2.4Ghz carrier to send at longer distance. ...
135 views

RMS value of fundamental harmonic vs RMS of third harmonic

If we have a periodic signal (square wave) with amplitude of 100V. Then what would the RMS value of the fundamental harmonic be compared to the RMS value of the third harmonic? After some suggestion ...
53 views

Difference between four matrices of state space?

I already know that there are two common types of representations used for mathematical modelling. One is transfer function and the other is state space. When dealing with state space representation, ...
28 views

What are the appropriate pulse width and PRF for a pulsed Doppler sensor

I have a raw k-band transceiver, radar-based 24 GHz, motion detector, IPM-165. and here is the datasheet: https://www.innosent.de/fileadmin/media/dokumente/DATASHEETS_2016/Datenblatt_IPM-165_V8....
45 views

Confusion regarding step responses of integrator and differentiator?

I am using matlab to study about step response of integrator and also of differentiator using transfer function modelling technique But i have two confusion, one in case of integrator is that step ...
144 views

Spikes in raw acceleration data from AC motor

I have an MCU with an accelerometer, tightly mounted onto an AC motor inside a production hall. Once an hour, it collects 1 sec. (Sample rate is 5000) of acceleration data for the motor and saves it. ...
71 views

How to determine value of t when plotting a signal

I'm trying to implement this model inatlab: I know that Ri = 2 and Si = -0.05+3j, ignore n(t). I want to plot the signal in time response, this is what I got so far: ...
34 views

How to obtain SNR when we have the samples of a non-DC noisy signal in practice? [closed]

This may sound a naive question but I couldn't find an example. Let me begin with what I know about SNR and where I am confused. Lets say I have a DC like signal with some random noise on it and I ...
52 views

Determine the output signal given the input and inpulse response

It's been a while since I've worked these types of problems, but I've been working out the following problem for a while now and can't figure out a few details: And here is the solution: ...
124 views

Potential hardware solutions to detecting which string/fret is being played on a guitar? [closed]

I'm aiming to translate sounds played from the guitar to guitar tabs (accurately). I've had a look at solutions for detecting which string is being plucked: Detect string plucking in electric bass ...
69 views

Measuring veloctiy by detecting objects with an analog sensor

I have a sensor (DRV425) which outputs an analog voltage. The voltage level changes to a lower voltage when the sensor pass an object. Please take a look at the screenshot. It shows the output signal ...
34 views

Sum of a piecewise defined discrete in time function

I have to make the sum from $-\infty$ to $\infty$ of the next function ($k\in \mathbb{Z}$): $x[n]=\left\{\begin{matrix} 3 &, &n=3k \\ 0 &, &c.c \end{matrix}\right.$ for ...
146 views

Generating square wave to be inputted into a MCU

There are signals like below picture inputted to MCU STM32f103: (Offset DC about 800mV, Vmax = 2.4V, f = 66 Hz) I want to change it to a squar wave from 0V to 3.3V being accepted voltage range for my ...
92 views

Vanishing of Gibbs Phenomenon in MatLab

I was trying to represent a square wave with its Fourier series in Matlab. But as I increased the number of terms in Fourier series expression, the Gibbs phenomenon vanished and the edges of the ...
3k views

Can sampling rate be a floating point number?

Suppose we have a sampling frequency for a signal of 15.5 samples/sec and we take samples for a period of 7 seconds. This means total samples are 108.5, does this make any sense? Shouldn't the ...
80 views

If I look at a signal in its frequency domain, are there some guidelines by which I can tell how that signal looks in the time domain?

I was studying the Laplace transform and the Fourier transform, and I can't figure out if there is some intuitive way of finding out how a signal looks in the time domain if we know its frequency ...
27 views

MEMS piezoelectric sensor circuitry

I have a question what exactly does a MEMS piezoelectric sensor chip contain. Does it contain the sensor element alone (or) also the signal conditioning circuitry for the MEMS piezoelectric sensor as ...
34 views

Filtering analog audio signal using TLV320AIC3111-EVM

I'm working on a project to filter analog microphone data using the audio codec from TI, the TLV320AIC3111. We are using the EVM However, I'm facing problems with implementing the filters on the ...
103 views

Guitar to MIDI conversion

I am wanting to measure the pitch of a single guitar string and convert into MIDI within 10ms. FFT takes too much time, I was wondering what other options are worth looking at? The main issue is ...
63 views

Monitoring 32 photodiodes simultaneously (all mounted on a flat surface)

I'm a total newbie here. I do not know much about circuits. So sorry for the newbie question and Thanks for helping! What I want to do is to detect position of incident light on this surface. For ...
52 views

How to see Signal frequency and Sampling frequency on the frequency spectrum

If I have a 100 Hz periodic analog signal and let us say it is band limited to 1kHz and I sample it at 3 kHz. If I want to see its frequency spectrum then how to differentiate between the signal ...
71 views

Can we use both FFT and PSD to obtain a random signal's frequency domain representation?

I always encounter random noise frequency domain representation as PSD(not FFT), something like in the below plot: Without diving into math too much, practically speaking can we always use FFT ...
57 views

Change of variable from t to $\tau$ during convolution

I am not able to understand that in the standard convolution formula how we can change the variable from t to $\tau$. $$\int{x(\tau)\cdot h(t-\tau)d\tau }$$ Isn't this incorrect mathematically?
79 views

Why rectification amplifies signal? [closed]

why a thermionic valve can amplify an electric signal (for instance, a radio wave or AC), by removing half of its phase? In other words, how is it possible that half-wave rectification can amplify the ...
27 views

How does spectral density of a power signal change when it is multiplied by $cos(2\pi f_ct)$?

Suppose we have a power signal $n(t)$ whose power- auto-correlation function is: $R_{n}(\tau)$ . Now we multiply the signal by a cosine as: $cos(2\pi f_ct) \cdot n(t)$, whose auto-correlation is ...
33 views

How do we interpret frequency from fft command in matlab?

How do we interpret frequency from fft command in matlab? When I apply fft to a sampled function(@ Fs) and I get peaks at some values in the fft array. How do I know what frequency in Hertz does it ...
59 views

Frequency/amplitude modulation and SNR

I read (for instance here) that FM modulation is less affected by noise than AM modulation. But I don't understand conceptually the reason for that: why is the SNR with frequency modulation higher ...
64 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 ...
32 views

Minimum Shift Keying

"Overall frequency excursion del-f in MSK is minimum frequency spacing between symbols 0 and 1 that allows their FSK representation to be coherently orthogonal". What is meant by being coherently ...
63 views

What is the correct instrumentation to measure a pulse height of 10's of microvolts with a pulse width of 10's of picosenconds?

I'm working with a sensing material and want to better understand its response. I have the theoritical elements worked out, but now want to begin testing and have no idea what type of tools/...
42 views

How to make a differential measurement using two single-ended circuits that are high-z isolated?

Consider this system: There is an AC source that is differential w.r.t to ground. To measure this signal, I setup a diff-buffer and then feed the output to an ADC which measures the differential ...
98 views

How can I vertically shift the voltage of a zero-centered signal such that I can read it with the Teensy 3.2's internal ADC? [duplicate]

I have a sinusoidal signal with a frequency of 100 kHz. It's zero centered with a peak-to-peak of around 3V (i.e. from -1.5V to +1.5V). I want to be able to read the peak-to-peak voltage with one of ...
72 views

Linear image sensor output signal processing

I am working on a circuit reading the TCD1103 image sensor. In the datasheet, the shown 2 peripheral components are advised. I wonder if the BJT connected to the OS signal would be neccessary, if an ...
47 views

Is it possible to measure impact force using Flexible PVDF Piezoelectric Film?

If it is possible , should i use integrator circuit first to hold the signal then follow it by other signal processing signals (amplification and noise filtering ) ? , knowing that i tried to connect ...
58 views

Bandwidth for a Butterworth filter

How to choose the bandwidth of a 2 pole Butterworth filter for QPSK modulation? What bandwidth should be chosen, if symbol duration is 10 ms? How to limit ISI for QPSK modulation?
62 views

What is the difference between using an USB Logging Software and Logic Analyzer for signal sent to the printer?

In my recent pursuit in exploring the workings of an inkjet printing head, I need information like the default firing voltage and waveform set by the printer's manufacturer for different instructions ...
178 views

Why is frequency of a sine signal is equal to its “rate of change of phase”?

I want to learn more about PLL but I'm stuck with the concept of "rate of change of phase" which is said that is equal to frequency. At the moment I'm very ignorant at the topic so I need to ...
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?
57 views

Peak Detector with Reset

I'm trying to make a N.Peak Detector with reset functions. I've tried various modification to the classic peak detector without any success. What I'm trying to accomplish is: Detect the negative peak ...
32 views

First-order hold interpolation in matlab

I have a sinusoidal signal x(t) sampled with period 1/fs. The result is the discrete signal x[n], where x[n]=x(t)|t=nT. Then I perform an upsampling of factor, let's say, 8 to increase the sampling ...
26 views

How to split mono signal to sterio siginal of AD9833 Sin wave generator?

I am sorry that I am not well aware in audio amplifiers, that's why I am asking this question maybe it's my stupidity. I have an AD9833 sin wave generator, I need to connect the AD9833's output to ...
2k views

Why would you put your input amplifier in front of your filtering for an ECG signal?

In this article at eetimes.com they show the signal chain for measuring an ECG. The raw signal of an ECG contains noise and offsets at least a magnitude larger than the real signal. (Some few mV ...