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0
votes
1answer
30 views

Select sampling frequency to closed loop control in a DC-DC converter

For a DC-DC converter in current mode control the control variable is the inductor's current, which at steady state is periodic. which is the ratio between the switching frequency and the sampling ...
1
vote
1answer
82 views

Trying to use MUCs to sample data from IMUs over bluetooth at a specific sampling frequency

I am designing a data collecting system and I want to be able to collect the data from both sensors at a rate of 500Hz. I was wondering if anyone could help me calculate/prove this mathematically ...
5
votes
3answers
158 views

Calculating FFT for only part of full frequency range?

Earlier I asked a question here about performing FFT at lower frequencies but still at high sample frequencies. I was under the impression that the FFT was inherently calculated at every frequency 0->(...
0
votes
1answer
32 views

Sampling circuit for decently high-accuracy ammeter?

I'm thinking about building a monitoring circuit for an existing residential power system. Currently there's a simple ammeter and digital voltmeter in use for some basic monitoring, but nothing fancy. ...
0
votes
1answer
31 views

Sampling Anti-Aliasing Filter Bandwidth

if i'm using Sampling frequency less than Nyquist Sampling frequency, Aliasing will occur which will scramble the whole signal, so one solution is to use anti-aliasing filter How can i calculate it'...
3
votes
1answer
44 views

In a Delta-Sigma ADC, does noise shaping bring the noise to the signal's frequency?

I'm trying to understand the Delta-Sigma ADC. It is known that it pushes the quantization noise to be in the higher frequencies (noise shaping). Since I don't quite understand how this works, I ...
-1
votes
2answers
52 views

Is an ADC with a serial interface slower than a parallel one, both having same sampling rates?

I am trying to interface an adc with an fpga, but I am running out of pins. I wanted to know if I use an ADC with a sampling rate same as the parallel one but with a serial interface , will I be ...
3
votes
1answer
57 views

How can any spectral analysis show that Sigma-Delta ADC reduces quantization noise?

Quantization noise refers to the modeling of the difference between an analog signal and its quantized version as an additive noise process. The power of the quantization noise can be calculated by ...
-1
votes
1answer
69 views

how i can get 5V AC output from 230V AC [closed]

how can'i get 5 V AC output 230 V AC: input? for a measurement unit bases on DSP?
1
vote
1answer
27 views

Sampling of non-baseband signals - Shannon sampling theorem

In the example on Sampling of non-basedband signals on Wikipedia, the author said it is sufficient to sample at 4 MHz (twice the width of the frequency interval). But how did the author calculate ...
0
votes
3answers
47 views

What is name of process used to change sample bit depth?

Changing sampling rate is called up sampling or down sampling depending on which way or is done. If the factor is an even number then the process becomes very simple. However, what term is used to ...
0
votes
1answer
58 views

sampling below nyquist frequency

Can someone explain me that when we sample that sinusoid with a frequency below the Nyquist frequency (below half the sampling frequency), why we end up taking two samples per cycle of the sinusoid?
-1
votes
1answer
54 views

\$e^{i2\pi Nf_snT}=1\$ why?

Why is: \$e^{i2\pi Nf_snT}=1\$ in snippet from book
0
votes
1answer
30 views

Low latency, high channel period wireless protocols

I was wondering if anyone can suggest any low latency high channel period wireless protocols or devices. I have been using the ANT and xbee chips to sample a digital signal however there channel ...
4
votes
1answer
94 views

How do I prolong the reed switch output time

I put a reed switch ( https://en.wikipedia.org/wiki/Reed_switch ) on the handle of a measuring wheel (perambulator). The reed switch will be activated up to around 20 times per second (every 50 ms). ...
0
votes
1answer
54 views

External ADC and FIFO

I have a Micro-controller with ADC input range 0V to 3.6V(12 bit). I need to measure a voltage signal in the range of -10V to +10V. So i chose the option of using an external ADC instead of the ...
-1
votes
1answer
22 views

Sampling alias phase when undersampling

I have to measure the sum of the magnitude of two sinusoidal signals and I think I can exploit the undersampling method in order to superimpose the alias of the sinusoid at the higher frequency over ...
0
votes
1answer
67 views

Sampling frequency and FFT

I have tried this example code for sampling and FFT in MATLAB, but I have noticed that when the signal frequency becomes closer to nyquist frequency , some errors ( small frequency components near the ...
1
vote
1answer
47 views

the voltage resolution for an analog signal with an amplitude

say,i have 16-bit DAQ that can read at a rate of 250kSamples/second. What is the voltage resolution for an analog signal with a 2V amplitude? For what value of signal frequency can I safely digitize ...
11
votes
3answers
594 views

Exactly what is the role of the zero-order hold in a hybrid analog/digital sampled-data system?

I'll admit, I am asking this question rhetorically. I am curious what answers will come back out of this. If you choose to answer this, make sure you understand the Shannon-Nyquist sampling theorem ...
1
vote
1answer
51 views

Non-unique Sample Rate

Given $$x[n] = \cos\left(\frac{\pi}{3} n\right)$$ That was obtained by sampling $$x_c(t) = \cos(4000\pi t)$$ At \$T\$ samples per second, find \$T\$. Is \$T\$ unique? Why or why not? $$x[n] = x_c(nT)...
0
votes
1answer
47 views

Getting a consistent and precise voltage for sampling

I have a 9V battery connected to an LM317T voltage regulator and it's regulating the voltage almost perfectly but I intend to use it for sampling and it fluctuates over a few mV. Generally between 1....
0
votes
1answer
53 views

Using an mbed and piezo disc to determine frequency

I am attempting to determine the frequency of an instrument from its vibration using a piezo disc and an mbed LCP1768. I attempted this with a raspberry pi but couldn't get the sample frequency high ...
1
vote
2answers
112 views

Power supply Harmonics calculation using FFT

I am trying to calculate harmonics of power supply with using a FFT. My sampling rate is 400 samples/sec. This means 8 samples per cycle. I am not getting sensible answers and think that I am making a ...
2
votes
3answers
139 views

Sampling rate for PID control to balance an inverted pendulum using 8051 - AT89c51rc2

I want to control a dc motor(to balance an inverted ;endulum) I want to sample the input from sensors(e.g.: ADXL345) and convert it to digital using a DAC. The maximum output data rate(ODR) for ...
0
votes
1answer
52 views

Sampling rate in dacs

I am using a DAC form analogous devices viz - AD565A. Now, according to Nyquist theorem the minimal sampling rate for a decent reconstruction of a signal twice the rate of its highest frequency ...
4
votes
1answer
126 views

256-point FFT, but only need 5-6 frequencies, is there a better way?

Due to the constraints of my system, I have a 256pt FFT. However, I only care about the energy at 5 or 6 of the 256 bins. 256pt FFT is still faster than 5 or 6 specific DFTs, but it seems wasteful ...
0
votes
1answer
86 views

can we achieve signal compression by reducing the sampling rate?

Does the reduction in sampling rate causes compression of the signal? If yes, can you please provide me some specific example?
0
votes
1answer
53 views

Sampling frequency range of an discrete signal

Is it possible to detect each and every frequency above the nyquist frequency? Or this can be also discrete Thank you.
0
votes
0answers
45 views

About coherent sampling

In Coherent sampling, it states the condition for coherent sampling is given by $$ \frac{f_{in}}{f_{s}}=\frac{M_{cycles}}{N_{samples}} $$ Where \$N_{samples}\$ value must be a power of 2 and \$M_{...
1
vote
2answers
277 views

Sampling rate analog to digital converter

I am a novice in microcontroller subject and have just learned that ADC converts analogue voltage on a pin of, for example, an Arduino, to a binary number. Since the ADC on the Arduino is a 10 bit ADC,...
0
votes
1answer
45 views

Received waveform frequency is way too low than it was sent

I am using Quartus 12.1 sp1, vhdl and Altera Nios II programmed in C code for DE0-Nano Development. Basically, what I have is, data is sent from fpga vhdl block to NIos II system, Nios II system sends ...
-2
votes
2answers
68 views

I need to sample 8 audio sources at audio quality, what MCU can I use? [closed]

I need to sample 8 audio sources at the same time, at a decent frequency (say, 40Khz). Being only familiar with Arduino, I searched online for tutorials and articles about using interfacing it with ...
1
vote
1answer
65 views

ADC samples half frequency

I'm using a dsPIC33F (Microchip) to sample a 555-timer signal. I've tried square, triangular, and "sinusoidal" signal shapes, but always have the same problem: the ADC samples the waveform correctly, ...
0
votes
2answers
122 views

Preparing Signal for Sampling

I want to sample a voltage signal from mains. I found the following circuit but im not sure how it works. The circuit consists of precision amplifier and a buffer which I can't make sense of, the rest ...
0
votes
3answers
159 views

Appropriate Method of Counting counts from a Quadrature Encoder

I'm using an Mbed to drive a DC motor which will follow a trapezoidal trajectory. What is the most appropriate way to determine position from the quadrature encoder? Should I use interrupts, or is ...
1
vote
1answer
153 views

Am I getting DC bandwidth correctly?

I am computing Johnson and shot noise in a DC circuit, where I have an Arduino Due sampling with "delay(100);", i.e. at 10Hz. Sampling rate and bandwidth follow Nyquist sampling theorem. According ...
1
vote
3answers
729 views

DSP Cutoff vs Sampling frequency question on low pass filter

Is it unrealistic to have a 125 MHz sampling rate with a cutoff frequency of 5 Hz? I downloaded a few filter programs and used their methods and it seems that even with thousands of taps it still ...
0
votes
2answers
158 views

Choice between Pseudo-Differential Unipolar and Pseudo-Differential Bipolar ADC Input

While reading about Pseudo-Differential Inputs for ADCs, I came across the document below from LT. Link : http://cds.linear.com/docs/en/product-selector-card/2PB_sarinputtypesfb.pdf Below are copied ...
0
votes
2answers
81 views

Sampling Signal using microcontroller

I would like to decode a signal from a radio clock source, using an off the shelf receiver, and a microprocessor. The output of the receiver is a digital level which encodes either carrier on or ...
0
votes
1answer
77 views

ADC output level query

This query is related to my old post: ADC outputs random values to constant input I made further tests, and still struggling. The reason I made a new post is, the query is different. I am using FPGA ...
3
votes
6answers
904 views

16-bit or 24-bit converters?

I wanna build some DSP effects on, for example STM32F4 processor, with frequency 96 or 192 KHz. Are 16-bit converters (ADC and DAC) enough for that kind of operation? Can I hear a diffrence when ...
2
votes
1answer
144 views

ADC outputs random values to constant input

I am using ADC (ADS7822) from TI and I have some strange behaviour with it. Below diagram explains the voltage inputs and connections. I was reading strange values with this setup. I removed ...
0
votes
1answer
59 views

why it is hard to generate an impulse train ?

I have understood the concept of Ideal impulse sampling ,but i have struck upon the fact that practically generation of impulse train is not possible.
1
vote
1answer
45 views

Source/Drain terminals in a MOSFET Sampling circuit

In a simple sampling circuit consisting of a MOS as the switch and a capacitor, how does one decide which of the terminals are source/drain? Thanks.
0
votes
1answer
191 views

Why does my bandpass RF filter complain about Ts in Simulink?

I am doing a basic amplitude modulator, and I'm using as input signal for now a Gaussian noise generator, then I modulate it with a carrier fc=2e9Hz. When using Simulink along with a RF bandpass ...
2
votes
1answer
260 views

Simultaneous sampling of several channels with single ADC?

I am looking at this 8-channel, 18-bit and 200 ks/s ADC. The datasheet claims the sampling is done simultaneously for all the channels, but the diagram shows that there is only one ADC, so how is ...
0
votes
3answers
468 views

Sampling Rate Passband Signal

What is the maximum/minimum possible sampling rate for the signal to be full recovered for a passband signal?
12
votes
2answers
576 views

Why doesn't aliasing of broad band noise 'pile up' in the sample band?

I recently built a simulation to study sampling, the effects of aliasing and the effects of anti-aliasing filters on the sampled signal. For fundamental frequencies above the sample band it's obvious ...
4
votes
1answer
2k views

Relationship of FFT Size, Sampling Rate and Buffer Size

I am asking this question because I want to make sure I understand the relationship of FFT length, the sampling rate and the buffer size. This question is with respect to the CMSIS DSP library, ...