Frequency Definition and 1000 Threads

This would appear to be a straightforward algebra problem, but it just doesn't pass the smell test for me. The issue might be with the number of electrons per cubic meter, as that was calculated in a previous problem, so let me know if that number seems wrong. My plasma frequency (##\nu##) not...

What property of a sinusoid makes it so special? I understand Fourier analysis, but really you could do Fourier using any periodic function as the building block. Sinusoids really do seem to be fundamental though, if you narrow the pass band of a filter with any random signal you will get a...

I am trying to simulate and process the Doppler signals. My main problem is a little more complex so I am only posting a simple version of it. Task1: I have a time-domain signal with the velocity of the target as mu. I need to change the velocity to mu cos(theta) where theta is a vector from 0...

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Now from physics I read that photons don't interact with one another normally, at higher energies they might through pair production but that is besides this point. So this means that for example if we have multiple sources of EM radiation like say multiple sub pixels within a screen then each...

Hello: Let's say you have a string and get data by changing the frequency a transverse wave in the string to get different standing modes. You measure the wavelength of each mode for each frequency. That is, the data you get are frequency and wavelength. Now, you are trying to find the...

Can someone give me a better intuition of bandwidth. The way I see it, is that the bandwidth is the range of frequencies which a signal/wave is allowed to have. This doesn't feel complete though. For example, how can I explain that TDMA, FDMA and CDMA are similar in this sense. As far as I know...

I've been searching the net but can not find any freely available literature. Can someone give me a quick lesson on boundary layer instability and its frequencies? I have an equation that claims to scale the instability frequency by: F = U/2*delta U is leading edge velocity delta is layer...

https://www.physicsforums.com/attachments/6-png.282284/?hash=0362cb24c9a8ed9b3ee9efab56a28e3d If the increasing frequency leads the current amplitude to increases, then Z decreases because V = I*Z and V remains unchanged...

Hi, I was reading through some online notes and was wondering: when dealing with coherent FSK, what is the minimum tone spacing and why? I know that for non-coherent FSK, we can show that the minimum is: ## f_1 - f_0 = \frac{1}{T} ## where ## T ## is the symbol period. However, if we are now...

I am trying to understand why the conjugate of a signal in the time domain doesn't produce an exact flip of the frequency domain spectrum. There is always a one-pixel shift in the result. The MATLAB code is shown below. I use a flip for the conjugate spectrum to show that it doesn't match the...

https://www.physicsforums.com/attachments/282201 Are we using this equation above to explain this question? The magnetic field is definitely in sinusoidal form but how does it proportional to the frequency of the source?

Hi, I was working through a filter design problem and got stuck on a concept. Scenario: Let us say we have the following pulse transfer function and the sampling frequency is ## f_s = 50 \text{Hz} ##. G(z) = \frac{1}{3} \left( 1 + z^{-1} + z^{-2} \right) The zeros of the transfer function...

I calculate as follow and get a correct answer, but I wonder why the weight of the ladder 6 kg is not included in the mass (m) in the numerator. w= √(mgd/I) = √ { （42*10*1)/ [(1/12)(6)(2^2)+42*1] } = √ (420/44) = 3.06

ω^2 - (ωo)^2 = 2 (-630) (0.32) = -403.2 This is what I have now and I stuck here.

The problem I am having is simple. I have a Gaussian spectrum initially. Like this, Process 1: S = m0/sqrt(2*pi*sigma^2) * exp(-(vel_axis - mu).^2/(2*sigma^2)); Here, mu is the mean velocity (frequency) and sigma is the standard deviation. vel_axis is the axis on which I am calculating this...

My lecturer said that the cryptosystem one-time pad, has a weakness which is when it is subject to frequency analysis. But after him trying to explain why that is a weakness of this system I am still unable to see why. Because the frequency of letters is completely irrelevant to the structure of...

So first I calculate the final velocity by multiplying the time by the acceleration, 9.8, to get 88.2 m/s. Now I use the equation. (343/(343-(-88.2))*108.3 = 86.1477. But the answer should be 88.47. What am I doing wrong here?

Hello all, I don't know if this is the correct place to post, but I'm looking to detect all electromagnetic waves around me that have a frequency that is under the visible spectrum. The reason is to try and get some kind of idea of what kind of radiation is around me, so that I can be more...

Using this stimulation: https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_en.html It looks like frequency is decreasing as I increase tension but online it says frequency increases as tension does. Also, I am unsure about what happens to the Period

Hi all Is there any way to measure frequency deviation in a recorded frequency modulated time domain data? The little research i have done on net mostly concerns with frequency deviation measurement using spectrum analyzer in real time i.e. data continuously received on spectrum analyzer while...

Summary:: How to keep the same voltage and change the frequency of a A.C. universal motor. Hello there! I need some help regarding my final project for the university. I have a universal motor, supplied by a single phase, 220V source. I need to make this motor work at the same voltage, but to...

Hello everybody . I would like to ask you for an opinion. audio waves passing through a horn or waveguide experience a small or relatively large distortion. do you think it is possible to eliminate distortion by making use of constructive interference?

Say we have a transform of a line profile that extends out to the Nyquist frequency such that you cannot see the noise level, what could you change in your spectrograph arrangement that would allow you to see the noise level in the Fourier domain? My thought is that we can apply a filter, P(s)...

Some RF transistors are not 'characterised' for lower frequencies, can they still be used? I get that a lower operating frequency (HF/1.8MHz) may not be the commercial target for an UHF transistor (>136MHz) so no effort spent on characterising them. Likewise HF transistors >1.8MHz not...

In the context of control systems, if I have a vibratory second-order system, (ω_n)^2 / [s^2 + 2ζ(ω_n) + (ω_n)^2], I know how to get the natural frequency ω_n. So, if I have something like 2 / (3s^2+5s+2), I know how to get the natural frequency ω_n. However, if I instead have something like...

Hi hi, I'm looking into how temperature affects waves, but I don't know too much about this, in how temperature mixes with all of this, I have this questions: We have a particle vibrating at frequency ##f## at a certain temperature ##t_p##, and a medium with other temperature ##t_m1##. If the...

AM/FM radio stations, cell phone towers transmit signals at certain frequencies. How can the frequency of a signal change depedning on whether the receiver is moving towards or away from the source? I thought that the frequency of an electromagnatic wave is determined at the source (the energy...

So first I made an equation representing the forces Fnet=kx-12.8v a=1/m(kx-12.8v). Now I am not really sure how to get w from this. I could argue the mass is at its max amplitude when a=0, but that wouldn't help me find w. If I say x(t)=kx-12.8v, then 1/m would be w^2, but this isn't right...

Explanation: y1=6cos(180t) ＋） y2=6cos(186t) y1+y2 =6cos(180t)+6cos(186t)y =6(cos(180t)+cos(186t)) cos(A)+cos(B)=−2cos((A+B)/2)cos((A−B)/2) y=6(−2cos((180+186)t/2)cos((180−186)t/2)) y=−12cos(183t)cos(3t) y=(−12cos(3t))cos(183t) Comparing with the standard equation...

Hi, On a driving force graph ##y = displacement (m)## and ##x = time## where the external force start at t = 0 and the system is in equilibrium at x=0, it's easy to find the driving frequency. $$F = \frac{\omega}{2\pi}, \omega = \frac{2\pi}{T}$$ and we can get ##T## easily with the steady...

First I tried looking at the units of the answer, 1/m. Frequency is also 1/s and since I also have m/s, if i divide the frequency by the wave speed I get 1/m (same units as the answer). This gave the wrong answer though. Next I tried looking at the equation at t=0. y(x)=Asin(kx+2pi). I can then...

So first I found what b/2m is and got 0.287129. Then I found what the sqrt part of the equation was and got 1.128713. Then I added them together to find w. Then I divided by 2pi to find frequency and got 0.255, but the answer is 0.180.

This is the FM demodulation "discriminator" circuit. It is one of the simplest analog demod setups one could think of. An RF (FM) voltage signal is applied at V12 and the voltage at ' a' ' is supposed to contain the AF signal in its amplitude. The idea behind the circuit is that it resonates at...

Under the topic of simple harmonic motion comes the composition of two SHM's with the same angular frequency, different phase constants, and amplitudes in the same directions and in perpendicular directions. composition of SHM's in same direction: say a particle undergoes two SHM's described by...

So, my thinking was that we use the formula V=f(lambda) and substitute the f so, V = 440(lambda) but then i don't have another number to cancel or rearrange by. And since closed air columns have the fractions of 1/4, 3/4, and 1 1/4 (5/4), we could divide by those?

How do I calculate a resonate frequency of a length of pipe submerged totally under water? Do I just take speed of sound in water which is 1,481m/s at room temp, and decided it by length of pipe in meters multiplied by 4? so at 20 celsius water and 20cm pipe it would just be: 1481 / (.2 x...

Hi, EDIT: apologies for any ambiguity, but this is for DISCRETE systems, not analogue like the problem states. I was attempting a problem which is shown below . I am not really sure how to attempt this problem, but here is my attempt. Are there general methods for tackling these types of...

The "egg" initially spun around axis 1 with at ##\omega_s##. After being disturbed, it has started to possesses angular velocities along 2 and 3. The question is to find the rotational speed of ##\vec \omega=\vec\omega_1+\vec\omega_2+\vec\omega_3## to a fixed observer. It is calculated that...

I attempted using f = 1/(2pi x sqrt l/g) For Earth I found the value of length to be 0.0276m. Then I substituted the value in the equation, putting (1/3)g instead of g, to find the value of f in Mars. My answer is C. I am confused. Please help me.

So I was reading my topic named "atoms" and got confused at a paragraph. It goes like this.. I encircled the paragraph when they told " "frequency of electromagnetic waves emitted by the revolving electrons is equal to the frequency of revolution" I got confused at 'frequency of revolution'...

Here an excerpt of my sample. In this case the minor contributors match 100% with a reference sample from a suspect. I am now to calculate the profile frequency to calculate the likelihood ratio. Do I multiply the allele frequencies of both minor and major contributor and use this value as my...

n1sintheta1=n2sintheta2 1*sin36=n2sin24 n2=sin36/sin24 n2= 1.45 to calculate wavelength is lambda=c/f My question is that that how do I find the wavelength without given the frequency.

I feel this is not correct, from my understanding of data, discrete data will always have a corresponding discrete frequency table and continuous data will always have a corresponding continuous frequency table. The class interval ought to be ##0≤x<5##, ## 5≤x<10##... i need clarity on this...

Two of my pupils in secondary high school is doing a project on the sound generated by striking glass bottles drumsticks. They fill the bottle partially with water and strike the bottle with a drumstick and record the sound. Preliminary results: As long as the water level is in the cylindrical...

I recently finished reading Paul Davies book The Eerie Silence, which is a book about the SETI (Search for ExtraTerrestrial Intelligence) project. In The Eerie Silence, Davies says that scientists using radio telescopes to search for radio messages from space aliens set their radio telescopes...

The hint says to use the moment of inertia of the rod, however i have not covered this on my course and I don't know what it is. After googling moment of inertia of a rod I found that it is a quantity expressing a body's tendency to resist angular acceleration, and for a rod I=1/3ML^2. So...

I'm currently trying to get my head around the properties of UHF vs VHF propagation, specifically to do with diffraction around terrain and obstacles of various sizes (i.e buildings, vegetation etc). I understand from experience that UHF is generally more suitable in built up, urban...

When I record slow motion video of my filament bulb lamp connected to mains, I can be completely sure that it flashes 25 times per second. This is half of the 50 hertz AC frequency. I would expect it to flash 100 times per second as the current reaches a node twice per cycle in it’s AC wave. Why...

I have a practical question about frequency estimation of a noisy sine In some of my experiments I need to estimate the frequency of a noisy damped sine. Currently I just use uniform sampling (sampling at times t=n*T) (making sure to exceed the Nyquist criteria) followed by an FFT. In the...