Questions tagged [sampling]

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56 views

RC circuit not ideal sampling

I have this circuit and I have to find \$x(t)\$, starting from \$ x_c (t) \$ I know that, at \$t=0\$, the switch is closed, so the capacitor is charged and, at the moment \$ x(n)T_c \$ the switch is ...
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6answers
2k views

Lossless compression technique for digital signals in an embedded system

Here's the scenario: I have an embedded system where an ADC logs a 16-bit potentiostat sample every 2 seconds. The system continues to record data for weeks, making memory usage a concern. Instead of ...
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0answers
26 views

Typical rms values for random jitter in satellite communication

I'm trying to find typical values for random jitter in satellite communication and I'm not really finding any values in any documents. Most of the time I only find definitions for different jitter ...
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1answer
47 views

Recording USB digital output (24-bit A/D) [closed]

I have found a 2-channel, USB-powered, ICP® sensor signal conditioner with USB digital output (24-bit A/D). It is supposed to provide me with a digital output that I should be capable to read from my ...
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1answer
29 views

Is HC-05 Bluetooth adapter suitable for logging fast?

Just bought HC-05 bluetooth adapter from Ching and I wonder how fast HC-05 is if I can do logging with it? Assume that we have a PC and a microcontroller. The PC have a FTDI232 connected to the USB ...
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1answer
42 views

Alias frequency

I have plotted the graph above that has an Amplitude of 1, and a Frequency of 1 Hz. Sampling rate used is 3/4 of a cycle. The book wants me to find out what the alias frequency that the green dots ...
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1answer
65 views

A general purpose way to connect cellphone line out to a microcontroller ADC

I have looked at many questions with similar titles but cone cover my query. Question: How can I protect an STM32 Cortex M4 series ADC input when measuring the AUX output voltage from typical ...
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3answers
66 views

Making Sense of oscilloscope specifications

When looking for oscilloscopes, you often see the following specs: bandwidth [in Hz] sampling rate [in Samples/s] capture rate [in waveforms/s] record length [in pts/channel] My question is: How are ...
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0answers
21 views

Continuous frequency grid to discrete grid

I am designing a controller for a system using several methods, one of which is a discrete method. In the continuous time I am looking at a logarithmically spaced frequency grid in the range $$\omega \...
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3answers
103 views

Why there is a low frequency?

I take the function \$ \sin(2 \cdot \pi \cdot f \cdot t) \$. with \$ f = 1 \$ And plot it in excel with sampling frequency fd = 4,10 Why there is a low frequency?
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1answer
53 views

DAC update rate vs ADC update rate?

I am building a system for ultrasonic distance measurement that implements CDMA coding access. Therefore, I am using DAC with 3 outputs for generation of three different signals and an ADC for ...
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4answers
99 views

How does oversampling improve the measurement precision?

Regarding improving the precision of a measurement, I have heard that a measurement precision can be improved by filtering or oversampling. When I think of filtering I can make sense because ...
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5answers
788 views

How can I know a signal's bandwidth before sampling?

Shannon's theorem tells us the minimum sampling frequency based on the bandwidth of the signal which has to be sampled. But I wonder, how can I know the signal's bandwidth before sampling it? It is ...
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2answers
81 views

Do we use any filter after photodiode?

In wireless communication, we use a matched filter to suppress out-of-signal-space noise. After this filtering we do sampling. Otherwise, the power of noise is infinite (practically very large). In ...
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2answers
56 views

Verilog: Sampling short, external, asynchronous input signals on a FPGA

I want to sample an external, possibly very short interrupt signal in my FPGA softcore. I did some research in some digital logic design books, and found this solution, where A is the input signal. ...
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0answers
46 views

ADC of TM4C123GH6PM( 1 Msps as given in datasheet ) is not reading any data if sampling frequency is increased beyond 250Khz

I need to sense a signal at 500kHz. According to the datasheet of the TM4C123GH6PM it is able to sample up to 1000Khz. The code is already written with sampling frequency at 90Khz. Whenever I ...
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1answer
75 views

How to enable the DMP of the MPU9250?

The datasheet mentions some Advanced Hardware Features which gets executed by the Digital Motion Processor. I'd like to use the ...
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0answers
74 views

How to transmit the data from the buffer filled with ADC values through DMA on STM32F7

I am currently trying to a sample a signal between 25-40kHz with three microphones to calculate the time difference. I'm having difficulites understanding what to do after the ADC is activated and ...
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1answer
55 views

the minimum cable bandwidth [closed]

In a sound recording studio 11 microphones are placed at different locations. The data from each microphones are brought to a processing center over wires and are sampled, quantized, binary coded and ...
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0answers
47 views

Sampling Capacitor In INA

I am looking at parts like the LTC2053 which use a sampling capacitor on their input. I had a few questions: Does the input impedance of this amplifier simply look like the sampling capacitor (1000pF)...
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1answer
98 views

Relationship between switching frequency and controller's crossover frequency in DC-DC converters

I am reading some answers related to my questions based on control loop stability of SMPS. I came across this question. The accepted answer states: A switch mode power supply is essentially a ...
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3answers
428 views

I2C data sampling is done at clock edge or level

I am trying to understand I2C data bus from this document. It explains the START-SLAVEADRESS-R/W-ACK-DATA.. as the master-slave take turns to get hold of the shared bus for mutual communication. One ...
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5answers
173 views

Sampling theorem clarifications

whenever the sampling theorem was explained to me, a situation of this kind was proposed to me. If we look at the previous image we will see that the condition to avoid spectral aliasing is that we ...
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0answers
69 views

Huge spikes and sudden offset in accelerometer data (FRDM-K64F & ADXL357)

I'm working with vibration analysis on electric motors (AC). I have a mBed FRDM-K64F with a EVAL-ADXL357 connected to it - mounted onto a motor. The device samples from the FIFO 4000 times per second,...
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1answer
30 views

Relation between spectral leakage and the frequency of harmonics of a signal

I'm currently studying "Data Acquisition". I read that when we have frequency/spectral resolution equal to a natural number, there will be no spectral leakage, for none of the harmonics. However the ...
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0answers
56 views

Sampling Frequency of a pulsed radar signal

I'm new to radar. please excuse my question if it doesn't make sense to you. In a pulsed radar signal, why is the required sampling frequency "2 times the inverse of pulse width" instead of "2 times ...
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1answer
49 views

Accurate signal reconstruction

While reading through this page I came across following info: "For accurate reconstruction using sin (x)/x interpolation, your oscilloscope should have a sample rate at least 2.5 times the highest ...
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0answers
30 views

How to measure the amount of light emitted back from a fiber optic cable?

I would like to build a setup where I use a light source to emit a signal over a fiber optic cable, and then measure the amount of light that is emitted back, e.g. by blocking/opening the other end of ...
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1answer
35 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....
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2answers
60 views

How to measure or estimate the phase delay between two analog input channels of this board?

There is a 16-bit data acquisition board with +/-10V range which multiplexes analog inputs and buffers the data to the PC. Specifications are given here (DAS6036 is the model in question). Now I need ...
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0answers
31 views

Necessity of PDM processing on the data given by an interfaced condenser microphone through ADC channel on stm32f4 discovery

I want to interface a condenser microphone with my stm32f407vg discovery board and obtain the audio output through the DAC audio jack. For the audio processing should I first convert the input digital ...
4
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4answers
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 ...
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1answer
112 views

Relation data-rate and bit-rate of ADC

I came accross the folowing question, where the accepted answer contains a formula showing the relation between bit-rate and data-rate for a delta sigma ADC. My question is, why that relation is valid....
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1answer
68 views

Sampling Frequency and Bandwidth

If i have a Buck Regulator switching at 200KHz and i want to sample the Voltage and current using OpAmp in tha path connected to ADC(12 bit). What would be the sampling frequency to measure the ...
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1answer
93 views

basic DIY function generator and scope

I'm currently traveling and only have access to basic parts (soldering iron, an arduino nano and a breadboard!) but I'm able to buy parts from local suppliers. for a project I need to be able to ...
0
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1answer
41 views

How does a fiber optic receiver converts the optical signal to an electrical signal

A fiber optic receiver needs to convert the incoming optical signal to an electrical signal so it can be sampled. How is this achieved in practice? I believe a photodiode is used, but would a ...
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0answers
51 views

Sampling Frequency of a delta-sigma ADC

For instance, let's take this delta-sigma ADC: http://ww1.microchip.com/downloads/en/DeviceDoc/22088c.pdf To calculate the average current and other important values for various sampling scenarios I ...
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2answers
367 views

Filtering an ADC input with an RC low-pass filter

I use an instrumentation amplifier to amplify low voltage signals from a sensor. The max. amplified output voltage is 3V. Im using this ADC: http://ww1.microchip.com/downloads/en/DeviceDoc/22088c.pdf. ...
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2answers
94 views

thoughts on reading only one changing GPIO with accurate time amoung huge number of digital Inputs

I am trying to read a huge number of digital inputs (129 to 800 and maybe more) at the same time. the sampling rate should be around 500K samples per second but I only need to read one of these inputs ...
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1answer
40 views

ADC bandwidth in excess of filter bandwidth

I am using a BPF of 5 to 300kHz on a pulsed input signal. Is there any benefit to digitizing at a rate significantly in excess of nyquist?
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1answer
113 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 ...
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2answers
311 views

increase the ADC resolution using oversampling [duplicate]

To increase the ADC resolution, oversampling technique can be used which must be followed by decimation (average) method. Oversampling is just take several samples within time period. Unlike the ...
11
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6answers
3k views

Why does increasing the sampling rate make implementing an anti-aliasing filter easier?

From an answer to a question regarding sampling rate and anti-aliasing filter I read the following: The closer you get to the theoretical minimum sample rate, the more difficult the analog filter ...
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3answers
105 views

Fastest temperature sensor for a bimetallic strip

What is the best approach or sensor to analyze the temperature of a bimetallic strip? From experimental data, the temperature swings due to a current flowing into the bimetal, are up to 80°C in a ...
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2answers
137 views

New Amazon music streaming service and Nyquist sampling theorem [closed]

I read this story on The Verge the other day, “It’s a better bitrate, better than CD quality,” said one of MBW’s sources, indicating the new service will put Amazon in direct competition with Tidal’...
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1answer
44 views

Input voltage on differential ADC (MCP33131D-05-E/MS)

I am evaluating a 16bit ADC (MCP33131D-05-E/MS) for my project. I want to sample in fully differential mode, but I have doubts as to what voltages are allowed on the Ain+ and Ain-. Signal ...
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1answer
98 views

Calculating sampling frequency off of estimated stop band attenuation

I'm trying to calculate what I will have to set my microcontroller's ADC sampling rate at in order to sample a band of 500kHz to 1.6065MHz without aliasing. Some constraints here are that I have to ...
4
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4answers
812 views

Is there an efficient way for synchronising audio events real-time with LEDs using an MCU?

I'm working on a project in which LED lights synchronise with audio events. I'm not referring to reactive LED projects that read the ADC from audio amplitude or spectrum, but about having some ...
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1answer
74 views

Possibility of effectively under sampling a band pass signal?

For a university project we have been tasked with implementing a digital signal processing system on an STM32 discovery board in which we must model the AM channel to measure and graphically display ...
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2answers
139 views

Maximum information Rate? [closed]

It is said that we can transmit at the most twice as many bits information per second as the transmission channel has the bandwidth. For example, 1 kHz bandwidth allows max 2kbit/s, if that rule is ...

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