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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1answer
23 views

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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54 views

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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86 views

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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3answers
212 views

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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1answer
129 views

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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54 views

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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1answer
54 views

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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1answer
98 views

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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16 views

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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2answers
152 views

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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1answer
60 views

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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1answer
57 views

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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39 views

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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2answers
31 views

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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28 views

What is an equation that will show RF wave characteristics?

I want to show a RF wave on a spherical grid coordinate system. How can I show the RF wave when t = time and y = magnitude? I also want to show curvilinear coordinate transitions of the RF wave ...
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49 views

Crystal oscillator frequency measurement disturbance

I've been building a 10 MHz crystal oscillator circuit (Pierce configuration) followed by a frequency mixer attached to it. The oscillator circuit and mixer are powered by an ordinary power supply. I ...
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10 views

Insertion loss measurements, frequency sweep vs measuring points with a constant driving frequency

I have been modelling a surface acoustic wave delay line, and am trying to clarify what I am seeing in the different models and whether this is applicable to what would occur experimentally. In the ...
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1answer
81 views

Measuring the quality factor RLC circuit

I am trying to get the Q factor for this circuit but I don't know how to simulate it properly. I did a frequency sweep from 1 Hz - 30 MHz. The oscillating frequency is 16 MHz. I can't get the ...
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2answers
57 views

How to transform an AC signal of wide voltage to pulses

I want to build a device that measures frequency of possibly different electrical alternators, not having much control of their parameters. For this I need to get digital pulses out of the AC signal ...
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1answer
56 views

How to measure laser class of LIDAR

I just bought a LIDAR with the intention of building an indoors robot that uses it to navigate rooms in my apartment. The manufacturer website states: Low power infrared transmitter conforms to ...
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2answers
36 views

Time Domain and Frequency Domain Amplitudes

I was wondering about these two graphs, the first is taken from an Oscilloscope and the second is taken from a Spectrum Analyzer. Why is the amplitude in the frequency domain close to 1/3 of that in ...
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2answers
93 views

Reducing the range of a D flip-flop frequency detector

I'm designing a frequency tracking circuit and I came up with a circuit that tracks frequencies from Fclk to Fclk/2: However, it would be very nice if the bandwidth was a bit narrower, from Fclk to ...
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157 views

wrong frequency of LC based generator with LM311

I have a problem with the frequency of LC meter based on comparator (a very popular solution, similar to this one: http://www.vk6fh.com/vk6fh/lc_meter_vk6fh.htm). I have recreated generator part in ...
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3answers
377 views

How to find the frequency of any device? [closed]

Are there devices which can figure out at what frequency every device transmitting radio frequencies operate at precisely? Say from a high of 2.4 GHz microwave to a low of 402 Hz pacemaker.
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1k views

Teaching about LC filters

I'm preparing to teach some people regarding filters, and I'm confused regarding the use of the LC-filter circuit, specifically the circuit below: simulate this circuit – Schematic created ...
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2answers
199 views

Non-intrusive measurement of current and voltage

Sorry if this question is too basic for this forum... I'm an interested amateur but far from a professional. I'd really appreciate information from someone more informed than myself. Hypothetical ...
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4answers
96 views

Frequency Ratio Circuit

I'm attempting to design a circuit that will determine the frequency ratio between a known reference frequency \$f_\text{ref}\$, and an unknown signal frequency \$f_\text{sig}\$. The signal frequency ...
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1answer
123 views

Methods of measuring speed of anemometer

I enjoy DIY, but to keep things simple I purchased an anemometer cupset (3 cups). I feel that a magnetic reed switch would get "bounce" at higher speeds and I was thinking of a disk with a slot, and ...
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216 views

Maximum switching frequency

Is it possible to calculate maximum switching frequency of IGBT having only datasheet in hands? https://www.semikron.com/dl/service-support/downloads/download/semikron-datasheet-skm200gal173d-...
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105 views

Rubidium standard mystery output?

I've been playing with a frequency counter (Racal 2202R) that has a built-in rubidium standard. It has two outputs, "Rb OUT 1" and "Rb OUT 2". I could not find any documentation at all, but the ...
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1answer
62 views

Unit conversion: dBμV to dBm, including measured frequency

I'd like to ask for help with conversion of measured voltage V=10dBμV to dBm units. Voltage is measured on frequency ...
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3answers
640 views

Is it possible to measure frequency upto 500Mhz with 50Mhz oscilloscope?

Is there a way to measure higher frequency measurements with a 50 MHz oscilloscope (eg rigol ds1054z)? Perhaps some post processing of captured waveforms? Or with the help of some adapters? I have a ...
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3answers
258 views

Measure frequencies fast and precise

I need to measure frequencies between 25kHz and 150kHz with a precision of minimum 50Hz. I'm using a MCU 8051(C8051F382 Silicon) with 48MHz clock, and need the measure to be done under 100us, so I can'...
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1answer
206 views

Circuit for converting motor tacho-sensor sine wave output to 5V TTL for MCU

I'm trying to measure the speed of a washing machine motor. The motor has a speedometer attached to it, which generates a sine wave with frequency equal to rotation frequency of the motor. I'm ...
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2answers
70 views

What are the methods to measure distribution transformer vibration in 0.5g range?

It may seem obvious to use widely available analog devices MEME accelerometer for measurement in range of 0.5g. I did thorough study on this and found out that MEMS sensors either doesn't work or ...
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1answer
81 views

Can the frequency of an electrical current be heard and distinguished from other frequencies just by connecting circuit to a speaker?

I have a circuit that I want to be able to detect the frequency of the current going on it (part of the circuit is AC, the power supply is going to be at least 3v, probably 5v, and 6v DC at most). I ...
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2answers
231 views

PIC period measurement sometimes 1 overflow count wrong

Short info: I'm using a PIC18F4580 to measure the period time of two positive pulses using the CCP 1 on the MCU. And then writing the result to an LCD. When testing I sometimes get a result thats one ...
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5answers
745 views

Reciprocal Frequency Counter Mean

I have designed a high precision frequency counter circuit. I am using it to measure a frequency of around 35kHz that is stable to 0.1mHz. I can measure the frequency using a Stanford Research Systems ...
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1answer
151 views

Frequency Counter Problem

I'm a Electrical Engineering Student and i have to respond to this question before I can do the lab work. "A frequency counter with an internal 1MHz oscillator and six frequency dividers is given to ...
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1answer
230 views

Enabling external reference to HP/Agilent Signal Generator (8648C)

What is the proper way to use an external 10 MHz clock signal for an HP/Agilent signal generator (in my case: 8648C)? With my Tektronix, Rohde & Schwarz devices, internal/external reference has ...
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2answers
3k views

LTSpice: How to use .meas command to find the fundamental frequency of non-sinusoidal signal?

I want to find fundamental frequency of a periodic signal (non-sinusoidal) in certain time window using the .meas command in LTSpice. I was using the following ...
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1answer
436 views

Simple way of measuring RPM of motor by How to make Frequency/Pulse counting circuit

I want to measure RPM of a motor. For this, I am planning to put an assembly where an IR LED facing with IR sensor under line of sight. With every rotation, the line will be cut once - and hence the ...
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1answer
78 views

Grounding oscilloscope probe effects

I have built an active band-pass filter on a breadboard with the use of an MC33078p op amp. Gain is 32 on paper. When I apply the AC signal to the circuit, 18.1mV P-P and 660kHz, the oscilloscope ...
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4answers
472 views

Differential Amplifier's Unusual Behavior

This circuit is made of one differential BJT transistor pair and voltage-amplification stage with negative feedback. simulate this circuit – Schematic created using CircuitLab About this ...
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3answers
236 views

Is a 0.01s time base really useful in a frequency counter?

I am currently designing a frequency counter based on the PIC16F628A. It is working as expected but I would like to add some useful features. According to the images found by googling, I noticed that ...
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1answer
153 views

Measure duration of a non periodic message on FPGA with VHDL

I'm trying to measure the duration of a non periodic signal(message) on FPGA, as below : I want to measure the duration of the measured signal by counting the number of reference clock's period. I ...
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0answers
460 views

interfacing tcs3200 color sensor with STM32f746zg

I want to interface TCS3200 color sensor with STM32f746ZG. Since the TCS3200 outputs a frequency based on the amount of light received, I need some way to count the number of pulses for different ...
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309 views

How are high-speed circuits tested if test equipment doesnt exist?

How was testing done for Ghz to THz range circuits and devices before fast enough scopes and frequency counters existed?
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326 views

Count based frequency meter

I'd like to understand how a frequency meter treats a sine wave, i think i got it, but still I'd like some confirmation. So i was taught with square signals where the meter counts the impulses in a ...
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1answer
136 views

What's the difference between measurement resolution and digits per second in time measuring devices

In time/frequency counters/analyzers in technical specifications you can almost always find resolution and digits per second values next to each other. What is the difference?