Questions tagged [frequency-measurement]

Anything related to the measurement of the frequency of periodic signals, i.e. the rate at which their waveform repeats along the time axis. The S.I. unit for frequency is **hertz [Hz]**.

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Frequency Counter Input Impedance

I have been looking at RF frequency counters and noticed that they all have one port that says up to 50 MHz with an input impedance of 1 megaohm. However the +50 MHz input says 50 Ohm impedance. If ...
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How to measure radio wave penetration and reflection through different mediums

I would like to do a few experiments to test how different EM radiation frequencies (915 MHz to 5 GHz) interact with 3D print filament materials (like PLA, PolyCarbonate, TPU, etc...). Specifically I ...
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IC for measuring frequency [closed]

In my application, I need to measure frequency in the 1 to 500 MHz range. Since this frequency is a bit too high for microcontrollers, I am wondering if anyone knows an approach to solve this problem, ...
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What is the shortest pulse a controller can count?

I want to count short LVTTL pulses (about 20-25 nanosecond.) Right now, I use an Arduino with four IN74AC161N binary counters, but this solution has some Arduino limitations. I count pulses, send the ...
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MAX9926 Maximum Variable Reluctance Input Frequency

I am planning on using the MAX9926 to read 2 variable reluctance (magnetic pickup) sensors installed in the crankcase of an engine. The sensors will read the teeth of the starting gear to get the RPM ...
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Gain at zero hertz

I have attached the figure of my circuit. I know that as the frequency rises the gain of the circuit decreases due to low pass filtering but what if I want to measure the DC output voltage ( 0 Hz) ? ...
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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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Linear and log sweep in AVR

My application requires a frequency sweep in a coil and measuring the resultant resonant frequency from the coil after it has settled. I can do the second part i.e. wait and count the rising edges of ...
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Measuring relative phase of two clocks

I'm working on an FPGA and I have implemented a component that can take a clock and dynamically change the phase. Now I think there are some problems with this component because the target of the ...
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Two resonances in the admittance of capacitor C

I have this question that has been haunting me for a week now. I was given a measurement file of a previous student. Allegedly, they are the measurements of the admittance of a circuit that is ...
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5 votes
2 answers
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Capturing mains AC waveform with audio recording device

I'm wondering how practical (read: safe) it would be to use an audio capture device to "record" a mains AC signal for the purposes of monitoring the characteristics of the AC sine wave. I am ...
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Degenerated signal at a logic level converter

I'm trying to pair a motor controller, and a bi-directional logic level converter to feed a microcontroller with a motor speed signal. Some signals have already been successfully converted, but a ...
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2 answers
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What sampling rate is needed for demodulating and decoding GPS signal data?

I just got a software-defined radio (SDR) and am trying to record GPS frequency (L1 1575.42 MHz). I understand that GPS is modulated using Binary Phase Shift Keying. I also read about the Nyquist ...
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Electret microphone amplifier to control an LED strip

First sorry about my English. So my problem is so simple but I can't figure it out. I have a frequency to voltage circuit which is working perfectly but I want to control it by the voice. https://...
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Negative frequency deviation in crystal oscillator

What is the significance of a negative frequency deviation in the freq deviation vs temperature profile of a typical OXCO (e.g. the diagram seen on this page)? My understanding is that a positive ...
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How to use the rate of change of frequency equation to calculate frequency drop in a grid based on lost generation

My question involves calculating the frequency drop in a power grid when a load is lost. The closest question I have found to mine is, Change in frequency in a grid that has lost generation? Based on ...
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The effects of frequency resolution in FFT on the frequency spectrum

This is a section for the parameter study of my thesis (basically: why and how I did what I did in the experiments). Currently, I have to choose the fit bandwidth and FFT lines combination for the ...
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how to apply frequency-dependent attenuation to a signal

Let's suppose a signal like this: the frequency domain plot of such a signal is: Now, What I intend to do is to apply a frequency-dependent correction to the signal. For example, the attenuation ...
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Measuring frequency of a coin vibration motor

I'm trying to determine the change in frequency with voltage of a coin vibration motor (https://solarbotics.com/product/vpm2/) using an oscilloscope. So far I have tried two different set ups. Set up ...
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Obtaining frequency of 550 Hz from Simple Triangle and Square Waveform Generator Circuit

First time asking a question so sorry if I miss some things. I'll try to be thorough and straightforward. I'm trying to design a square wave from a triangle wave-square wave generator circuit. The ...
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1 answer
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1200W, voltage and cycle converter 220 to110

I have bought a Joule sous vide immersion circulator from USA. I want to use the device in India. I need to convert AC, 240V 50Hz to 110V 60Hz. After reading the literature on the company's website ...
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2 answers
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Simple high frequency (GHz) RF radiation detector

I want to build a simple RF radiation detector that shows if there are any RF devices transmitting at a certain frequency. I want to use it to detect RF radiation in the 2.4 and 5 GHz range. I have a ...
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How to measure microwave frequency with Lecher lines

I am working on a project where I need to measure the frequency of some microwaves (up to 10GHz) and as measurement tool I chose Lecher lines as they are easy and fast to build. However after building ...
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How to identify the type of modulation and data rate of an RKE system transmission

Many devices that measure frequencies of key fobs, can inform, in addition to the frequency measurement, also the type of modulation, FSK or OOK, and the data rate in bps. Previously in this forum, I ...
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Which frequency measurement method is more suitable for RF signals from 200MHz to 915MHz?

I need to build embedded circuit, an RF frequency meter (also known as RF frequency counter) to measure frequencies of remote key fobs. The frequency range I need to measure is 200MHz to approximately ...
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Steps for connecting femal-to-female sacrificial adaptor into a male connector in the RF measurement equipment

First of all, I am a newbie to the RF-mm-wave test equipments. I am trying to use this Agilent equipment shown in the image below where I want to connect a 1.85mm (F-to-F) sacrificial connector to the ...
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Sensitivity of a frequency meter

Can I know the sensitivity of a power frequency measurement unit? I can not find it in the specifications sheet. I do have, though, the accuracy of the unit (10 mHz) Thanks in advance!! Update : I am ...
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Measuring the resonant frequency of a crystal

I am trying to measure the frequency of crystals in my box. I have a signal generator set to output a sine wave at 5V p/p. The output is applied to the crystal and then the other lead of the crystal ...
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Why the same sound source (low frequency, possibly infrasound) has different frequencies in different rooms of the house?

Can someone explain me why the same sound source has different frequencies in different rooms and if there is some type of correlation between the vibrating frequency and the distance between the ...
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LockIn Amplifier Noise measurement

On my understanding, a LockIn amplifier use an internal (or external) signal source, set to a given frequency, say x. The system locks into that frequency, which means only that frequency can be ...
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2 votes
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Frequency to volt conversion problems

Converting frequency to voltage using LM 331 is causing me problems. Frequency range: 0-200 Hz V.out ref: 3,5v at 100 Hz (3000 RPM) 5,0V at 150 Hz (4500 RPM) V.cc: 12v. A sensor picks up the mpulse ...
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Frequency response measurement problem with mobile phone: same (wrong?) readings for different speakers

I have built some bespoke speakers and tried to measure their frequency response. My rig is: Source: Android phone Samsung A3 as a source, playing frequency sweep using Android's Frequency Generator ...
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PWM signal not visible upon increasing the scope time base

I am capturing 2 different PWM signals. The frequency of first PWM signal is lower when compared to the second one. Please check the waveforms. All the waveforms are taken of the same two signals. ...
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Digital Frequency Measurement

The circuit in the figure below is a circuit for measuring frequencies for RKE systems (a key fob, for example). The frequencies for which this circuit was created, was used to measure frequencies ...
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High pitch audio frequency measuring

Wondering on how could higher pitches than 23 kHz be measured, I can only find devices measuring to about 21kHz. Main question is: how could audio frequencies about 26 kHz or 30 kHz be measured, on ...
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1 vote
1 answer
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Frequency Measurement using FPGA and VHDL [closed]

I am not very experienced at VHDL coding. I want to measure the frequency of my input signal. It varies between 1 Hz to 150 kHz. And my clock frequency is 250 MHz. I wrote some code but it is not ...
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Timebase Ground-Loops - why place the isolation transformer at the input instead of the output?

In the course of investigating the construction of a home-made 10 MHz lab frequency reference I wondered if the output from such a reference should be isolated. I came across a small article about ...
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Open-source DIY audio spectrum analyser and/or graphic equaliser

does anyone know of any OpenSource/DIY audio spectrum analyser projects can they direct me to an article, video, pics hackaday and instructionals style also I.C's old or new that i could/should try ...
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Equipment and approach for performing a long-term measurement of clock signals

This is a follow up question for the circuit I designed with the inspiration from here. The circuit works but over time there appears to be some clock jitter or skew. I am interested in an approach to ...
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Determining changing values of C in RC circuit

My problem is related to the change in the membrane capacitance of a cell (link to paper). The electrical properties of the cell can be modeled using a battery, a resistor and a capacitor in series. ...
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Does frequency scale proportionally?

Suppose that I am working with an FPGA and I synthesize two architectures A and B. A achieves a maximum frequency of 60 MHz on FPGA and B achieves 50 MHz on the same FPGA. Now suppose that I ...
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Raspberry Pi and FFT (Fast Fourier Transform) -- Using MCP3208

EDIT: I've made adjustments based on your answers, while I couldn't get it to be evenly spaced, I managed to get a better curve with more samples per cycle. Turns out I need to remove the print ...
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How to identify remote keyless entry (RKE) frequency?

I need to design a system able to identify which frequency is being used by remote keyless entry (RKE). I found that the wireless carrier frequency can be 315MHz in the US/Japan and 433.92MHz (ISM ...
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Why most measurements equipment uses 10 MHz as reference?

This is just a question about this value of frequency. I mean, this is a industry standard, to use 10 MHz as a reference, but, where this value comes from? Is this something historical? That a ...
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Low Pass Step and Low Pass Pulse sith Vextor Network Analyzer

I have an extremely basic question about time domain measurements with Vector Analyzer. It is something that is not explained in simple words in all datasheets/guides (maybe they think it is obvious ...
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Tool for measuring the frequency of a crystal oscillator

I am building a digital clock from sequential logic. I’m using a 32.768kHz crystal with a CD4060 IC. I’m looking for a tool to measure the output frequency. I currently have it hooked up to an LED ...
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FFT in oscilloscope measuring Frequency spectrum

I am using a Keysight InfiniiVision MSOX3054T Scope having Bandwidth of 500MHz and Sampling rate of 5Gsa/s. I am learning to use the FFT Option in the scope. Below is the waveform I captured of my ...
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Noise on probe while measuring Switching Frequency of Buck Converter

I have a buck converter and I am measuring the voltage ripple at the output capacitor along with that I am measuring the switching frequency at the cathode of the diode. Please refer the below image. ...
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Frequency Sweep

I have heard the term "Frequency sweep" in testing context. I want to understand, when we say frequency sweep, we give a start frequency and a stop frequency. Assume a function generator with a ...
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Effect of the horizontal magnifier control on the sweep speed, sweep time and number of cycles observed?

What is the effect of the horizontal magnifier control on the sweep speed, sweep time and number of cycles observed? Sweep speed increases by ten times for a 10X magnifier, sweep time reduces by the ...
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