# Questions tagged [sampling]

Periodical measurement of an electronical property of a system, most often voltage.

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### Sample and Hold IC specification

I am currently designing my 3rd year project in EE. I have an MCU with an ADC that samples at 15 kHz. The signal I want to sample has a 0.5 µs rise time which is equivalent to a bandwidth of 700 kHz, ...
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### Oscilloscope Low Sampling at uHz Sinus Signal

I tried to measure a sinus signal at 1000 µHz with my R&S RTC1000 oscilloscope (bandwith 300 MHz). The function generator that I used was the EDU33212A. I set the T/div=100s and the oscilloscope ...
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### Oscilloscope Total Record Samples Vs Signal Frequency

I have the oscilloscope R&S® RTC1000 at 300MHz / 2GS/s / 500Mpts (Mega Points) with 12 horizontal divisions on the screen. 1st Example: If I have a signal 1Hz the total samples that the ...
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### Sampling frequency of ADC and maximum frequency of input signal

As pair the datasheet of LTC2207, maximum input frequency can be 700MHz. whereas the sampling frequency is 105MSPS. Two times 700MHz is way less than 105MSPS. So how is this not contradicting with ...
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### Help with inverse Z transform

I have the following function on time domain $$f(t) = sin(100 * 2 * \pi * t)$$ and I need to get its discrete values when it's sampled at 1000Hz. After applying the Z transform and using T = 1/1000, I ...
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### Do industry true RMS volt meters use a transformer?

I'm trying to build a true RMS volt meter that plugs into my 120 RMS outlet. Since I want to do it safely, I'm using a very handy transformer (ZMPT101B AC voltage transformer module) that takes the ...
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### Delta Sigma Modulator for 2/3 Multi modulus divider used in FracN PLL

I have been trying to implement a Delta Sigma modulator for a 2/3 Multi Modulus divider. I am referring to Riley's paper: https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=229400 I have designed ...
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### How can the ADC bandwidth be higher than the sampling rate?

From a hobbyist perspective, the sampling rate of an ADC must be at least twice of the input signal. As I was looking for an ADC to digitize a demodulated signal, I found that some ADCs like the ...
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### How to measure and sample oscillations in a LC tank using a Microcontroller

Since the oscillations in a LC tank starts with high amplitudes and dies gradually, and since the first oscillations are to some extent unpredictable in amplitude, how can one measure and sample such ...
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1 vote
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### Arduino's impedance in breadboard circuit

(Warning, as this is a long question, asked by students that don't know what they're doing. Perhaps our questions are too general and can't be answered but at this point we'll take all the help we can ...
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### Reason for the degraded I2S signal

I'm working with one of the devices from the NXP's IMX family - the IMX93 evaluation board. I've managed to setup the sound card drivers already, the next step was to test I2S signals output via the ...
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1 vote
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### SDR Bandwidth and sample rate

I saw that SDR has two parameter: bandwidth and sampling rate. I would like to know the difference between them because i saw a 56MHz bandwidth SDR but by looking at the chip used inside the sampling ...
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### How to properly compute noise power spectral density?

I am confused about two different definitions of Power Spectral Density (PSD) that I have seen online. The first comes from the National Instruments LabVIEW documentation (1):  PSD = \frac{PS}{\...
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### Effect of 2ASK Sampling Points on Bit Rate

“I reduced the only one sampling points while using 2ASK modulation, and the bit error rate increased by 20%. Can you help me with this?” Question happens in this line: ...
1 vote
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### Digital Low Pass Filter and PWM Signal

I have a PWM signal going into an ADC. After the ADC the signal is being filtered using an IIR single pole filter. Performance is exactly what I want with one exception. The purpose of the filter is ...
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### embedded system STM32F4 ADC sampling rate

I am new to embedded systems. I done a bit of analogue circuit design but nothing connecting analogue circuits to a STM32 via ADC. I am using STM32F4 microcontroller and had couple of questions. I ...
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### Signal Processing Question--old school [closed]

I have a signal generator that creates a mostly 8kHz sine wave signal, with a couple quirks. It repeats in a 96ms pattern. Output is 220mV into a 1-20 ohm wire. It is used to provide wire guidance ...
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### Experiencing Much Higher Data Rate than Timer Interrupt Settings While Reading IMU Data via I2C on Arduino

I am currently using an Arduino MKR ZERO to gather IMU data from three MKR IMU SHIELD boards(BNO055 IMU). I have utilized the <Adafruit_ZeroTimer.h> library to set a timer interrupt with a ...
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### How do you find Image Rejection Ratio from doing FFT on ADC samples?

I'm trying to understand a particular code written by a former employee for measuring performance of an RX chain in a transceiver. I have to measure IRR(Image Rejection Ratio). Certain input RF ...
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### Why do oscilloscopes list max bandwidth separate from sample rate?

I would figure that if a scope has a sample rate of 200 MSa/s, it should be able to measure signals up to its Nyquist frequency, 100 MHz. But there are a lot of scopes whose max bandwidth do not match ...
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### ADC sampling time longer than expected

I have noticed an unexpected behavior with the ADC of a STM32l0 microcontroller on one of my projects. I’m trying to read 3 channels as fast as I can. My signal is buffered with an OPA127 op-amp that ...
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### Determining the sampling rate / frequency from a graph

I don't understand how the two graphs in the image below are connected. The context is signal processing and sampling rate (+ its relation to bandwidth). I don't know the exact terms to look up. I am ...
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### Help understanding Sampling rate, ODR and oversampling of BMP390

I'm trying to understand how fast I can measure pressure changes with the Bosch BMP390 sensor, but there are a few parameters in the datasheet that are confusing me and I would like to understand how ...
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### What are SAMPCON and SHI?

The paper " The design of analog signal communication system based on visible light ", Z.N. Zhang and H.Y.Y Hua., describes a communication system using VLC technology. There is this part ...
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### How to achieve coherent sampling in practice

In the context of measuring a sinusoidal source with an ADC, coherent sampling (i.e. capturing an integer number of periods) allows the use of a rectangular window without spectral leakage. How does ...
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### Decode chirping frequency with uC at center frequency of around 100kHz

Context For my MSc project I'm building a chirping signal (a bit like LoRa) with a center frequency of 100 kHz. For now, the bandwidth is 10 kHz such that I have around 10 periods per chip. For ease, ...
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### STM32F407 ADC setup problem: ADC sampling continues despite delay in code loop

I'm trying to control the sampling rate with a delay function. I'm using channel 0 on ADC at PA0. This is how I've set it up: ...
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### Wheatstone bridge analysis

Hello, I am facing issues in calculating few parameters for the following information. I am new to this concept of strain gauge, wheatstone bridge, and data acquisition system Four resistive strain ...
1 vote
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### Why doesn't the sampling rate of the ESP32 go any higher than 10 kHz?

I put this simple code in the Arduino IDE. I expect a message in the serial monitor every second saying time for 50000 readings is 1 millisecond. ...
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### Are the subjects "button debounce" and "Nyquist–Shannon sampling theorem" related or not?

My understanding: Regarding A/D conversion of a signal: The Nyquist-Shannon sampling theorem states, that an analog signal can be fully reconstructed (D/A converted back) if the sampling rate is >= ...
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### Fourier transform plot

A continuous-time signal x with bandwidth $\frac{20π}{3}$ rad/sec is sampled with sampling period $T_s = 0.1$ seconds to obtain a discrete-time signal $x_s[n] = x(nT_s)$ for all n. The discrete-...
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### I want to divide a pulse in time axis and create more pulses

I need help with my project. I want to split a pulse on the timeline. I want to take the signal and divide it by 58 μs. Actually the time of the output signal is not important. I just need to generate ...
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### Best way to drive high speed ADC with differential inputs

Currently I am using AD8137 to convert my single ended signal to a differential signal. The ADC I am using is ADC3422 from TI and the data sheet suggests a passive circuit to drive low frequency ...
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### What methods can be used for sampling an analog signal using a microcontroller?

I'm in the early stages of design a project I'm working on for fun - a radar speed detector using a simple Doppler radar module and an Arduino (or possibly another similar microcontroller). I've ...
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### Limit of daisy-chaining of multiple ADCs

I am designing a device consisting of 20 daisy-chained ADCs (https://www.analog.com/media/en/technical-documentation/data-sheets/ad7685.pdf) communicating via SPI with the STM32F303 microprocessor. I ...
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### Sampling bottleneck due to sensor conversion time? MAX6675/MAX31855

The datasheets for the MAX6675 and MAX31855 say that their "temperature conversion times" are 220 ms and 100 ms respectively. I am using an arduino to get the data from a K-type ...
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### Extending signal duration

I have DMM which is producing pulse with duration of around few microseconds. The pulse need to be sampled in PLC, which has sampling rate of 1ms. In other words the cycle loop can't be reduced to ...
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### How can I find what the sample rate is if I measure it continuously for 100 times?

I am using Adafruit ItsyBitsy, and an external ADS1115 ADC module. I am continuously measuring the voltage using ADS1115 via loop 100 times. ...
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### Effect on sampling time on BER

Just for some background context: A digital signal has jitter present on it. In this situation there is only random jitter (RJ), which is unbounded and normally distributed. When the digital signal ...
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### How to characterize an input signal?

I'm planning on doing some signal processing on my electric guitar with an MCU and I was wondering how I can characterize my input signal so I know if and what kind of pre-amp/ADC I'd need or if the ...
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### Convolution between bit stream sampled by N number of samples per bit with a channel modeled as low pass filter

I generated a bit stream in MATLAB, from the transmitter to be convoluted by the channel I use MATLAB function "randi" between 0 & 1, so it generates random vectors of 0s & 1s and ...
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### Calculating 3-phase real and apparent power using sampled signals

Using step-down/isolation transformers, I am sampling the phase-to-phase voltages of a 3-phase, 3-wire industrial utility system in the US (208Vrms, 60Hz). Additionally, I am sampling the line ...
1 vote
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### How to minimize vTaskDelay in FreeRTOS?

I need to sample a signal with a sampling frequency in order to 2500 Hz. But, when i put any time in vTaskDelay(pdMS_TO_TICKS(time)) under 1 [ms], my programa start to bug. How can i fix this? Note: ...
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### Digital up conversion and digital down conversion

Description: I’m trying to use the standard sample rate of 61.44 MSPS on both sides of my digital transceiver(DUC and DDC,) so I’ll upsample my data from baseband data rate 3.84 MSPS to 61.44 MSPS ...
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### Is it viable to use a Raspberry Pi with ADC to send, receive and process ultrasonic signals

I want to take a laptop-based ultrasonic radar system and convert it to a hand-held device. I have Tx and Rx filtering circuits already, now I need to decide on what to do the signal processing on. ...
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### How can a lidar achieve cm-level resolution?

In order to achieve cm-level resolution, it seems like a lidar would need to have extremely high sampling rates. Here's my thinking: Light travels at roughly 3·108 m/s, or 3·1010 cm/s. We need to ...
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### Frequency converter for spectrum analysis

I have an oscilloscope/spectrum analyzer that has a maximum sampling frequency of 20MHz and I would like to analyze the spectrum of a higher frequency band (also 20MHz wide) for example 90-110MHZ to ...
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### Sampling a continuous time signal in a DSP

We are tasked with sampling a continuous time signal in a DSP. Before sampling, the signal goes through an analog filter of which I know the continuous frequency function H(ω). I also know the Fourier ...