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Author Topic: How far can ultrasound hit a target through Heterodyning?  (Read 1927 times)

Offline mriver8

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And at what frequency can ultrasound destroy hair cells?


 

Online evan_au

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Re: How far can ultrasound hit a target through Heterodyning?
« Reply #1 on: 07/09/2014 04:42:58 »
Ultrasound can burst cells, but it is not just determined by frequency - the amplitude (power) and focus is also important.

Modern electronics (and even old valve amplifiers) can generate considerable power at ultrasonic frequencies without the use of heterodyning.

In what way were you thinking of using heterodyning?
 

Offline mriver8

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Re: How far can ultrasound hit a target through Heterodyning?
« Reply #2 on: 07/09/2014 05:05:49 »
I wasn't thinking of using it myself. I read something about the tech, and was wondering how far would it enable ultrasound to be delivered through the air?
 

Offline mriver8

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Re: How far can ultrasound hit a target through Heterodyning?
« Reply #3 on: 07/09/2014 05:38:05 »
See page 20 to 26 what is the freq and what methods can be used to block it?

https://docs.google.com/viewer?a=v&pid=explorer&srcid=0B-C2IpG-te-Lblhhd2V2eEh6WUk
 

Online evan_au

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Re: How far can ultrasound hit a target through Heterodyning?
« Reply #4 on: 07/09/2014 07:54:54 »
Quote
enable ultrasound to be delivered through the air

I notice that the lower frequencies were in the hearing range of cats and dogs; it would be very distressing, and would damage their hearing. Cat and dog hair would move in response to intense ultrasound, and may damage hair follicles.

Humans can't hear ultrasound (that's why it's "ultra"), and we don't have that much hair, so its not clear if it would have the same impact on humans.

If you want to deliver ultrasound efficiently, you won't deliver it through the air, as there are severe impedance mismatches between the transmitter and air, and between the air and the skin.

For medical ultrasound, they use a gel between the transmitter and the skin, to maximise power transmission, and minimise reflections.

I see that some of the tables were using exposure times of 1 hour. I can imagine a weapon that requires the enemy to remain in the same place for an hour in the presence of an ultrasound transmitter.

The best defence against a painful ultrasound weapon is to "run away; run away quickly!".
 

Offline mriver8

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Re: How far can ultrasound hit a target through Heterodyning?
« Reply #5 on: 11/09/2014 00:52:26 »
Yeah but I don't think the exposure was more then a few minutes for the destruction of hair folicles at freq somewhere between 200KHz and 3MHz I think if I'm reading it correctly? Also do you have a good link that explains the realationship between microwave pulse radiation and ultrasound waves?
 

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Re: How far can ultrasound hit a target through Heterodyning?
« Reply #5 on: 11/09/2014 00:52:26 »

 

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