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Questions tagged [digital]

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2answers
2k views

Analyzing a 16-QAM modulated waveform?

Okay I'm really confused about analyzing the waveform I generated using 16-QAM on MATLAB... I transmitted a $y = [0 \ 1 \ 2 \ 3 \ 4 \ldots \ 15]$ discrete signal (in order) to ...
4
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1answer
26k views

what's the pass band ripple and stop band attenuation of a digital filter?

Hi i'm a beginner in signal processing i want to know what'sthe pass band ripple and stop band attenuation of a digital filter ? Thanks.
4
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1answer
248 views

Why in Overlap Save Method in DSP output length comes out to be same as input length?

I know that when we do convolution of $x(n)$ (Length $L$) and $h(m)$ (Length=$M$), length of output data comes out to be $L+M-1$, but when we break a large sequence of data and find output using ...
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2answers
72 views

Why the correct probability for a square M-QAM is equal to the square of correct probability of ($\sqrt M$)-PAM?

The question is why: $P_c (\text{square} $ $M-QAM) = (1 - P_{\sqrt M})^2$ where: $P_{\sqrt M}$ is the error probability for $\sqrt M$-PAM signal. Thanks.
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3answers
244 views

Sampling and Reconstructing Digital Signal

Say that I have a digital signal (a bitstream actually) whose output changes every 100 mS. I don't know exactly when it changes relative to my sampling, only that that the next bit to capture appears ...
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5answers
358 views

Differentiating between zero and not sending for OOK

How would a trigger works for on-off keying (OOK)? How would it differentiate between not receiving anything and zero?
2
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1answer
18k views

What is the difference between continuous, discrete, analog and digital signal?

It's my first time studying DSP and I've faced a problem finding a convenient definition. Are the following definitions correct? And if so why there are some resources defining it in other terms such ...
0
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1answer
57 views

Canonical Rectangular Modulation

http://zone.ni.com/images/reference/en-XX/help/371025N-01/loc_eps_rectangular_modulation.gif I just wanted to make sure that my assumption that in this figure $\phi(t)$ is representing $m(t)$, and $R(...
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2answers
632 views

Detecting which digital number an image represents

I photograph the dashboard of my car every day to register the mileage for work. I use OpenCv to detect the region of the digital displayed mileage, crop to the numbers and match them. The method I ...
1
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2answers
604 views

Calculation of actual analog input from bipolar ADC's output

I have a $14$-$\textrm{bit}$ ADC which can take $-10\textrm{ V}$ to $10\textrm{ V}$ as input. So, $0$ to $16383$ (digital) represents the voltage from $-10$ to $10$. If I want to get the actual ...
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1answer
265 views

why does the decision boundary change in BPSK? is it true?

I am working on modulation and demodulation of BPSK using python. i made a code for modulation and demodulation,while demodulate i tried to compare my actual data bit stream with demodulated bit ...
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3answers
174 views

Linearizing digital-analog converters

I'm looking at ways to improve the effective resolution of DACs. It seems that element mismatch (i.e. integral non-linearity) is the main contributor to distortion in modern DACs. Apart from ...
1
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1answer
77 views

Digital Filters deal only with samples, right?

I'm new to digital filters. So I'm trying to get things right and I can't find an explicit answer to my question on the internet. Question: Digital filters only accept samples as input? I mean the ...
2
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1answer
200 views

2D Digital Signal Processing - Applying High Pass on and Image

I have been doing my research on 2D digital signal processing. What I am doing is about noise removal of digital image: Type of noise that I want to remove from an images is like the Gaussian noise ...
2
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0answers
1k views

Simple (Arduino) digital butterworth filter : why do I see oscillations?

I want to filter deviations from an ADC over time (low pass), not very critical. So I first tried exponential averaging, something like y= (7*y+x)/8. That gave useful results, but there is an obvious ...
2
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2answers
341 views

DAC to Analog Filter to ADC

As the order of filter needed for digital information gets higher, it takes longer to process and requires more memory. Maybe analog filtering could be of use here. I know that the words analog and ...
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1answer
1k views

System characterization given pole-zero mapping

The figure shows the pole–zero plots for three different causal linear time-invariant systems with real impulse responses. Indicate which of the following properties apply to each of the systems ...
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1answer
318 views

What would the plot of an two sided digital signal look like?

Please, take a look at section, 1.2.3 (Signal Duration), Page-03, of the book Shaum's Outlines: Digital Signal Processing by by Monson H. Hayes. According to the definition, I can imagine how a ...
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1answer
46 views

Find $X_s(f)$ of a sampled continuous signal

I've been trying to find the transform of the following signal, but have not been successful, any help would be greatly appreciated: Find $X_s(f)$ of the following signal the "mathematical DAC" ...
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2answers
4k views

Why is cos(n/6) aperiodic?

This is a very common example in most Signal Processing books I have come across. x(n) = cos($\frac{n}{6}$) is a non-periodic discrete signal because it doesn't satisfy the periodicity condition for ...
3
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1answer
2k views

Understanding “voltage” and “power” in SNR of a sampled signal

I'm facing a gap in my understanding of when a signal is a "voltage" signal and when it is a "power" signal that I've always managed to avoid resolving until now... First what I think I understand, ...
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2answers
408 views

Design one of 4 type of FIR filter by window function?

There're 4 type of FIR to chose from symetry ,even symetry ,odd antisymetry, even antysymetry, odd Also, there are many type of window like rectangular, Hanning, Kaiser,etc So how to use a window ...
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3answers
142 views

What is the transfer function of this block diagram

I and my friend have different answer for this block diagram Mine: $$y[n] = -\frac23x[n] + x[n-1] -\frac12[n-2]$$ Hence $$H(z) = \frac{1}{-\frac23 + z^{-1} -\frac12z^{-2}}$$ My friend: $$q[n]=x[n]-...
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1answer
129 views

About output signal digital band pass filter

I try to use the butter worth pandpass filter to retrive the OSC from signal y showing in Fig3. The output signal is as in Fig4. We can see from Fig4 that I have retrived the OSC successfully. But ...
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1answer
2k views

Exact definition of soft bits in digital receiver

At which stage of digital receiver, the bits are considered as soft bits? I am unable to find the exact definition. I have rough idea how soft bits are different from hard bits but in terms of signal ...
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1answer
163 views

how much of DSP (digital signal processing) is related VLSI?

Although,this question may not be very much related to the topic of discussion, but i just wanted to know how much of DSP (digital signal processing) is used in VLSI. Like in the industry or for the ...
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2answers
1k views

Digital signal derivative

I'm new to signal processing and I need your help: I have an array of 128 elements (call it Window) filled with 128 samples taken from a sensor. I was wondering how ...
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0answers
146 views

How can I convert a FM discriminated signal to binary data using software

I currently have FM discriminated data in a .wav file. How can I convert it to binary data (+0.5 == high bit, -0.5 == low bit) given a baud rate.
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1answer
3k views

Differential BPSK vs BPSK what are the advantages and disadvantages?

Recently I have come across different variation of the sane modulation techniques. I am quite confused about the advantages of different constellations. In particular, what are the advantages of using ...
0
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1answer
313 views

Nyquist rate and oversampling

Assuming we have time domain signal $$x(t)\,\,\,\,\,\,\, 0\leq t< T$$ and we decide to upsample the signal by factor $L\geq1$. Then the samples of this oversampled time domain signal are ...
0
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1answer
149 views

What are the units of amplitude of my ultrasonic recording equipment

I'm not familiar with the topic of sound. I have ultrasonic audio recordings sampled at 250kHz (16bit) in WAV format. The equipment used to record them is linked here: http://www.avisoft.com/usg/...
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1answer
45 views

Concepts Surrounding First Two Samples in Difference Equation

I'm attempting to construct a difference equation in matlab for the function u(n) and find the auto-correlation matrix R. I'm following the technique as is defined by my text below: The system I'm ...
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2answers
1k views

Transmission Bandwidth and Sampling frequency

In LTE standards, for a transmission bandwith of 2.5 MHz, the sampling frequency is 3.84 MHz. I was wondering with this choice, are we violating Nyquist theorem? I found the details in the following ...
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3answers
3k views

what are frequencies in a digital image? [duplicate]

I don't completely understand the term " frequency" with respect to digital image processing. for 1D electrical signals , its pretty easy to understand , visually too. higher the frequency - more ...
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3answers
443 views

Can OFDM modulate analog signal?

I suppose that OFDM can't modulate analog signal. The basic mathematical description for OFDM is $$ v(t)=\sum_{k=0}^{N-1}X_{k}\exp(j2\pi k t /T),\quad 0<t<T$$ In this equation, $X_k$ is a ...
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4answers
50k views

Difference between Digital signal and Discrete signal

I have just started studying Digital Signal Processing. Can someone explain what is the difference between a Discrete Signal and a Digital Signal in simple words? Thanks in advance !
2
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1answer
153 views

Shouldn't the Sampling Theorem imply that there should be no information loss at all after a signal is processed?

I am very, very new to signal processing (only started a few days ago) so please bear with me because I may be missing the big picture. Consider an arbitrary signal $x(t)$ with varying frequency to ...
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2answers
1k views

Digital low-pass filters; best practice application

I have time domain strain gauge data from a structure which is subjected to low frequency, random loading. The signal / noise ratio is pretty good, but I would like to try to improve on it as much as ...
1
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1answer
396 views

Total Harmonic Distortion calculation and its origins

I ve been researching about harmonic distortion and THD. From what i ve seen on the internet, HD is caused by non-linear signal processing. I want to calculate it using an digital signal processor. ...
0
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1answer
38 views

z transform property question

I have a few questions about this assignment I am solving. It is q3.33(a) from oppenheim's DSP book 2nd edition. basically, the question gives you a pole zero plot, from which I was able to ...
2
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1answer
772 views

Creating a digital filter, from Laplace to $\mathcal Z$-transform (zero order hold) to code?

I'm trying to create a digital filter in code(C) but any language is fine. Now I've got an analogue filter that I have represented by an equation in the Laplace domain and I want to try and implement ...
0
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1answer
64 views

Estimate digital signal

I have a device that connect with USB to my computer. This device have digital signal that I can sample it every few seconds. The signal that the device perform, is a digital signal with $X$ seconds ...
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2answers
7k views

C/C++ library for digital modulation [closed]

Is there a library written in C/C++ that offers functions like QPSK modulation?
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1answer
3k views

Digital Gaussian White noise signal generation in C++

I am trying to generate a band limited noise signal on a Raspberry Pi. I calculate samples at every 1/48000 sec on the Pi. If I generate normally distributed random numbers as data points at every ...
4
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1answer
282 views

Is it possible to do further beamforming on already beamformed data?

I've a circular array of eight FM antennas. I'm doing digital beamforming to form eight beams with the following beam patterns: The objective is to reduce my side lobes even further, and to get ...
2
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3answers
85 views

Papers for Teaching an Introductory Course in Image & Signal Processing

I'm preparing a digital signal/image processing introductory course and, besides the theory and practices I want the students to read and discuss a couple of research papers during the last one or two ...
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1answer
344 views

Analog vs. digital communications in PCM and noise [closed]

How do you determine if you are using analog or digital communications? For example when dealing with PCM and noise how can one notice any difference in the signals when using the two types of ...
1
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1answer
508 views

How Radix-8 and Radix-2^3 are related

How are Radix-8 and Radix-2^3 FFT are related? Are they same? I got some more details in IEEE paper by S.He and M. Torkelson, "Designing pipeline FFT processor for OFDM (de)modulation," in Proc. Int....
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2answers
295 views

Complex numbers in a frequency domain of a 2D image [duplicate]

I am try to grasp the idea of frequency domain for images. I think get the basics, but now I've stuck with a question that I can't find appropriate answer anywhere. How are frequency domain and ...
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2answers
47 views

Inverted values - digital resolution issue?

first of all, I am not a technician, but I would really appreciate your helping with one (I hope simple or trivial) issue. I recorded a signal (skin conductance level - SCL, uS unit) with my device - ...