Question on Waves: Pulse Scattering in Dispersion Medium

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In summary, the conversation discusses the effects of dispersion on signal transmission through a dispersive medium, such as water. It is mentioned that pulses (sound waves) will scatter due to the varying velocity dependent on frequency in the medium. However, this is not considered true scattering since it is not caused by an abrupt change in properties. The conversation also touches on the use of frequency and amplitude modulation in ultrasonics and the limitations of signal transmission in electrically conducting water.
  • #1
orange
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Hey! Thanks for taking your time to read this question.

In a dispersive medium, the velocity is dependent of the wave's frequency. If you would send a signal through pulses in a dispersive medium such as water, would this not mean that the pulse will scatter?

Bye!
 
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  • #2
When you say signal, do you mean something like applying frequency moduluation or amplitude moduluation so the sound waves?

I am mostly familiar with applications of ultrasonics in which the frequencey and amplitude are invariant (fixed by source transducer), and the applications are very short range.

Over what distances would you apply this signal transmission?

Pulses (sound waves) disperse period.

IIRC, scattering occurs at distinct boundaires (such as gas/liquid or liquid/solid) or where there is an abrupt change of acoustical properties.
 
  • #3
Since a pulse is composed of a spectrum of frequencies and the medium is dispersive then the pulse will spread. This is not usually regarded as "scattering" which, as Astronuc properly points out, only occurs when there is an abrupt change in the properties of the medium, i.e. the change occurs on a scale comparable to or smaller than the wavelength of a given spectral component.
 
  • #4
Astronuc said:
When you say signal, do you mean something like applying frequency moduluation or amplitude moduluation so the sound waves?

I am mostly familiar with applications of ultrasonics in which the frequencey and amplitude are invariant (fixed by source transducer), and the applications are very short range.

Over what distances would you apply this signal transmission?

Pulses (sound waves) disperse period.

IIRC, scattering occurs at distinct boundaires (such as gas/liquid or liquid/solid) or where there is an abrupt change of acoustical properties.

Thank you for your answers Tide and Astronuc. I was thinking of any distance and for any kind of wave, including electromagnetic pulses. Sorry for being unspecific.

I had this scenario going; When, let's say, submarines communicate under water, they'd probably send pulses of radio waves to each other. Since the frequencies in the signal pulse travel with different speed the pulse will be spread and maybe unrecognizable when it reaches the other sub.

The spreading of the pulse will of course be very, very small. But let's say if it were to travel many times around the globe, the pulse would be worthless, correct?
 
  • #5
Orange,

I don't know the specifics of dispersion by ocean water but you have the right idea. There's just one thing, however. Ocean water is electrically conducting which makes it difficult to propagate all but the longest wavelength electromagnetic radiation.
 

1. What is pulse scattering in dispersion medium?

Pulse scattering in dispersion medium refers to the phenomenon of a pulse of energy being scattered as it travels through a medium with varying properties, such as a mixture of different types of particles or a medium with changing temperature or pressure.

2. How does pulse scattering affect the propagation of waves?

Pulse scattering can cause changes in the direction, speed, and intensity of waves as they travel through a dispersion medium. This can result in phenomena such as refraction, diffraction, and attenuation.

3. What factors affect pulse scattering in dispersion medium?

The properties of the medium, such as the types and concentrations of particles, as well as the characteristics of the pulse, such as its frequency, amplitude, and shape, can all affect pulse scattering in dispersion medium.

4. How is pulse scattering in dispersion medium studied?

Scientists use mathematical models and experimental techniques, such as scattering experiments, to study pulse scattering in dispersion medium. They also use computer simulations to visualize and analyze the effects of different parameters on the scattering process.

5. What are some real-world applications of pulse scattering in dispersion medium?

Pulse scattering in dispersion medium has many practical applications, such as in ultrasound imaging, radar technology, and underwater acoustics. It is also important in understanding the behavior of light in different environments, which has implications in fields such as optics and telecommunications.

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