Questions tagged [sampling]

In signal processing, sampling is the reduction of a continuous-domain signal to a discrete-domain signal.

113 questions with no upvoted or accepted answers
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Stochastic process inference from partial observations

Consider a set $U$. My signal is a piece-wise constant "function" $Sig: t \mapsto s$, i.e. the signal at time $t$ equals to some subset $s \subset U$. One can see $Sig(t)$ as a stochastic process. ...
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30 views

Model-based Kalman filtering a noisy signal

In a healthcare application, I need to calculate urine flow by differentiating the mass of urine emitted by a person over time. The measuring instrument consists of a load-cell under a fluid container,...
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58 views

Minimum time delay that can be estimated between two sensors

Consider a 1-dimensional toy problem. I have two sensors at different points along the $x$-axis. Somewhere away from the sensors, a disturbance is created which travels towards the sensors, first ...
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0answers
741 views

Sinc interpolation formula for signal reconstruction in frequency domain from bipolar samples

As per the title, I was wondering if there was a $\operatorname{sinc}$ based interoplation formula for reconstructing a signal in the frequency domain which has been sampled with respect the bipolar ...
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459 views

Interpolating on the borders of differently-resolved images

I'm creating a three-dimensional model of the earth based on SRTM height data. The data set is pretty huge, so only a small fraction of the data is available at any given time. The height data is ...
3
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160 views

understanding discrete wavelets

I was reading section 4.3.3 from chapter 4 of "A Wavelet Tour of Signal Processing", "...Let $\bar{f}(t)$ be a continuous time signal defined over $[0,1]$. Let $f[n]$ be the discrete signal obtained ...
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40 views

Intuitively, why is the comb function the sampling function?

The comb function can be used to sample a continuous signal. The comb function is defined as follows $$ C_T(t) = \sum_{k=-\infty}^{\infty} \delta(t - kT) $$ where $\delta$ is the Dirac function, ...
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100 views

How do I extrapolate a 1D chirped signal?

Following a past question, I'd like to extrapolate a signal like the one below: (red is signal, blue is the the extrapolated ) ...
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52 views

How can I extract the 2 polyphase components of a signal after sampling at the half of sampling rate

Suppose I have a continuous signal x(t), which was sampled using sampling function s(t) whose sampling rate is Ts.How can I sample the continuous signal by Ts/2 instead of Ts in order to get two ...
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0answers
136 views

Noise PSD and sampling rate relation

Let's consider generating samples of a random process like white Gaussian noise (AWGN). Let's assume I am generating $N$ samples of AWGN with variance $\sigma ^2$ in MATLAB by using randn() funtion i....
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45 views

Hardware selection for acquiring signal in digital form

I want to it clear that I am a mechanical engineer and so my knowledge on electronics and signal processing is limited. I am working in a hydrophone system. My job is to find the position of an ...
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3answers
1k views

Aquila DSP C++ Library - Wave file FFT analog frequency off by factor of 4?

I'm working with the Aquila C++ DSP library. I'm computing the FFT of a wave file (16 bit depth, single channel, 44100 sample rate). I am using a window size of 16384 to calculate the FFT spectrum. I'...
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0answers
79 views

Why does filtering the same discrete dataset while choosing different sampling rates yield different results?

If I have a two-dimensional discrete dataset (one space, one time), and I create subsets of this dataset by "sampling" (although the original dataset isn't continuous) it at different rates, should I ...
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0answers
642 views

Fast DSP with in-chip ADCs

I'm looking for a DSP, around 500MHz, with an in-chip ADC (preferably 2 but 1 will suffice) that samples around 20MSPS. Does any such DSP exist or do I have to use external ADCs?
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128 views

Upsampling Methods for Computed-Tomography

I have two sets of data of given Field of view, one of them only covers a subset of the FOV of the other. I therefore want to upsample the one with the larger FOV to combine it with the other one. So ...
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127 views

Instantaneous Frequency variation

I am looking for a method to calculate the instantaneous pitch variation within a speech signal for time-warping application. Sample by sample frequency variation knowledge within a frame will give ...
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0answers
113 views

Voice sample prediction scheme

I have some telephone voice audio with occasional "blips" in the audio. The blips appear to come from an IP link buried in the PSTN (this is a conceptual explanation, so don't worry about things like ...
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0answers
16 views

Continuous-time RNN and Shannon sampling theorem

The most-used discrete-time RNN equations used in Deep Learning these days are those of Elman: I have seen two very different continuous-time version of these, with different justifications. The most ...
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2answers
65 views

Multiple different length Windows for high resolution realtime FFT

I am looking at trying to achieve a 'realtime' (as quick as possible to acquire, process and present data) FFT application to analyse audio. I have setup my app to acquire a set of samples, apply a ...
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0answers
34 views

Why is my resampled signal cutoff when resampling with a windowed FIR filter in MATLAB?

I have an exercise to write a function which upsamples or downsamples a signal by a factor of F (integer) using a FIR filter windowed with a Kaiser window function. Exercise I had last week included ...
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76 views

How to obtain the steady state response of the sampled periodic signal data?

Below the green plot Vin is 5Hz sine voltage signal from a function generator output sampled at 12kHz sampling rate: The blue plot Vout is the processed/filtered data by using the following code in ...
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51 views

Proving Nyquist Sampling theorem for strictly bandlimited signals

I understand that the Nyquist sampling theorem dictates that the minimum sampling frequency, $f_s$, be s.t. $f_s > 2B$, where $ B $, is the bandwidth of the signal. I have read the explanation for ...
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1answer
65 views

Signals sampling

I have a simple question, but sadly I'm kind of "noob" in signals theory. A signal having 4 harmonics at the following frequencies: 1 kHz, 2 kHz, 3.5kHz and 4.2 kHz. (How can a signal have harmonics "...
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63 views

How to sample a transfer function (angular spectrum) in the frequency domain?

I am having this problem in Fourier optics, where I am using the Angular spectrum method (a lti filter) to calculate the electric field at the required plane given ...
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0answers
80 views

Matching two signals with small time drift

I have two time-domain signals sampled at 100 Hz that were measured using two different oscillators and therefore have a time drift between them. I have two synchronization points, one at the start ...
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1answer
99 views

about sampling frequency

I am trying to make a DFT on a signal with frequency f=50 MHz main component plus some noise. As far as I know if I sample it at F=100MHz I should be able to get a proper plot of the DFT since F=2f ...
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59 views

dsPIC33E ADC to FFT help

I am sampling an audio range signal with a bandwidth of 3100Hz and then applying a FFT using the DSP library example from Microchip to determine the most dominant frequency of the signal. On the last ...
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0answers
17 views

artifact identification in irregular-samped data

There is a dataset combined by different datasets a,b,c,d,e. The time intervals are irregular(i1, i2, i3:intervals between a and b, b and c...), but the sampling rate SR in every single dataset is the ...
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45 views

What kind of signal reppresents this Power Spectral Density?

I'm sampling 8 bioelectric signals with a embedded board which use an 8-channels ADC (AD7175-8). My sampling rate for every single channel is about 6250 Hz. When move the analysis in the frequency ...
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1answer
192 views

Determining sampling rate for signal reconstruction

I want to know how to determine the signal sampling rate required to reconstruct electrical signals whose frequency components are unknown, such as, for example, signals of charge/discharge voltage on ...
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2answers
1k views

What is the difference between the sampling frequency of signal and sampling frequency of filter

I believe that there is no connection between the sampling frequency used for converting an analogue filter to digital filter and the one used to sample a signal that the filter will be used on. But I ...
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0answers
31 views

Signal view from two different receivers (of the same model)

I have two SDRs hooked up to two different computers, both radios tuned to the same frequency. They sample at 2Msps. What I would like to do is start up both (at 'about the same time'), and, after ...
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1answer
68 views

Sub nyquist sampling, required number of samples for time sparse grouped signals

Question: Does it make sense to perform compressed sampling if the non zero samples are grouped in time? If so, what is the minimal length of the vector x that should be acquired to allow full signal ...
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1answer
111 views

Continuous wavelet transform subsampling at lower frequencies?

I am not completely confident in my understanding of wavelet theory, but since I am currently in the process of creating a CWT scalogram tool, I have to ask: Is there a theorem allowing us to ...
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0answers
59 views

Real-time DAQ (Data AcQuisition) device and filtering of voltage signals in audio frequencies

I'm working on a frequency mixer project in which two analog voltage signals at two different frequencies (each <5 kHz) are considered. I'd like to add the two fundamental frequencies and return an ...
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0answers
154 views

What is advantage of Logarithmic Sampling?

Logarithmic Fourier Transformation This paper starts off in the abstract saying that the given audio signal is sampled logarithmically. We also know that the human ear has a sort of a filter bank ...
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97 views

Can picking an inappropriate roll-off frequency for a digital filter just alias the roll-off value?

I believe a related question is asked here, but my question deals more with what filter is realized if one fails to consider design parameters relative to sampling rate. In designing an IIR filter we ...
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39 views

Number of trials to judge performance of Compressive Sensing recovery algorithms

I'm trying to get a conclusive numerical value for Mean Squared Error (MSE) as the performance metric of a few CS sparse recovery algorithms. To do this, I vary the number of measurements ($M$) taken ...
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0answers
111 views

DAC output SFDR and Harmonics does not meet at particular decimal frequencies

We are using a current output DAC to perform waveform generation in the band of $20\textrm{ MHz}$ to $500\textrm{ MHz}$ and sampling at $1.2\textrm{ GHz}$. SFDR and harmonics suppression requirement ...
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40 views

DWT initialization from nonuniform samples

Let $D\subset\mathbb R$ be compact, let $f:\mathbb R\to\mathbb R$ be a contintinuous function with support $D$. Let $\phi(x)$ be a well-defined scaling function, in the sense that it generates a ...
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0answers
7k views

Flat top sampling to a step shape signal

Flat Top Sampling During transmission, noise is introduced at top of the transmission pulse which can be easily removed if the pulse is in the form of flat top. Here, the top of the samples are flat ...
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0answers
377 views

Sampling and zero crossing

I am sampling a sine wave of 50Hz(stepped down from 230V) at the rate of 500KHz. For identifying disturbances in the wave, i was thinking of comparing a cycle of incoming sine values with reference ...
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0answers
204 views

Why is it better to sample white noise in frequency domain here?

We have a channel $c(t)$ that we want to sample. It can be expressed as $ c(t)= g\ast x(t)$ where $x(t)$ is white complex Gaussian noise and $g(t)$ is a function that we know the PSD of, let's call it ...
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39 views

Find unknown broadcast frequency

I'm very new to this stuff, so please excuse the dumb sounding terminology. I'm trying to capture the data from my elster smart hydro meter. How can I find its frequency (I know its between 902 and ...
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0answers
79 views

Non-uniform sampling and over-sampling — how to combine?

My instrument performs measurements at non-equal time intervals, i.e. non-uniform sampling. Apart from this, I usually oversample (by a factor of $n$) for reasons related to filter design, and ...
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0answers
479 views

Difference between note based (MIDI) and sampled (FLAC, MP3, etc.) audio formats

I (somewhat) understand sampling and sampled formats, and their relation to the original (analog) signal, but do not quite relate it to note based (MIDI) formats. What actually is a note based audio ...
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39 views

How to proceed with this convolution problem?

If $$\alpha_k = \sum_l a_l \ \ g((k-l)T-l\Delta T)$$ $$s_k = \sum_l \alpha_l \ \ q((k-l)T+k\Delta T)$$ where $a_l \in \pm1$ and $g(t) = \frac {\sin(\pi t/T)}{\pi t/T}$ and $q(t) = \frac {\sin(\pi t/(...
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308 views

Chip rate and sample rate

If a sequence of +1 and -1 with chip rate ($\frac{1}{0.57 ns}$) is being used for purpose of estimating channel impulse response with delay spread of 6ns. We decide to have a new rate change to rate ...
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0answers
43 views

Is Bernstein ever used in DSP?

In the early 1900s, Bernstein proved you could approximate any continuous function with the sums of polynomials. I know this is a bit weak for DSP because it isn't strictly periodic, but is Bernstein ...
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199 views

how to solve the sampling rate conversion problem

I am trying to improve my DSP knowledge and this problem is too much for me. I am trying to solve following task: this is not a homework. any help will be appreciated.