Filter design

[Electronman]

So my circuit has reached to that freq, WoW

 

[Sceadwian]

Not likely electronman, normal speakers won't produce that frequency. It was possibly a fluke, besides if I'm not mistaken only echo location sounds are that high their normal calls are similar to bird chirps.

 

[audioguru]

Your 40kHz carrier is a square-wave that has a lot of harmonics. If it is a perfect square-wave then its even-numbered harmonics like 80kHz, 160kHz etc. should have a very low level. The 3rd harmonic at 120kHz will have a high amplitude.

 

[Nigel Goodwin]

Well several days ago I read a paper about creating audio from ultrasound. So I want to design a circuit to do a similar task.
I have to filter out the output to create SSB or VSB somehow.

You guys, please let me know If those high pass filters which I designed (the above pictures) cause the output to be VSB if they do not remove the toltal lower side band?
If I am can not to create a good filter for SSB then I want to create a filter to truncated the lower sideband of the dsb with carrier signal. Any suggetion?

I've not followed the rest of this thread, but bat detector circuits are commonplace and simple - I've no idea why you're talking about sidebands and SSB?.

Mixer, local oscillator, audio low-pass filter - end of story.

 

[audioguru]

There is a company that produces high power ultrasonic transmitters that are modulated with speech and a sophistocated algorithm. When the ultrasonic wave strikes an object like a statue in a muzeum then the speech appears to be produced from the statue.

The company claims that the ultrasonics can be modulated with different languages and the modulation can be heard when the beam hits a person. The beams are very directional so people over here can hear one language and people beside them can hear another language.

I don't know if the ultrasonic beams are single-sideband.

 

[Sceadwian]

The army actually has a few test units that use large ultra high powered versions of those panels to disorient/disable (maybe kill) people at a distance.

 

[Electronman]

Your 40kHz carrier is a square-wave that has a lot of harmonics. If it is a perfect square-wave then its even-numbered harmonics like 80kHz, 160kHz etc. should have a very low level. The 3rd harmonic at 120kHz will have a high amplitude.

Why the third harmonic will have a higher amplitude than other ones?

 

[Electronman]

I've not followed the rest of this thread, but bat detector circuits are commonplace and simple - I've no idea why you're talking about sidebands and SSB?.

Mixer, local oscillator, audio low-pass filter - end of story.

Are not those circuit just a bat voice RECIEVER? I think they just detect the ultrasonic waves generated by BATS, Right?
My circuit CALLed a bat By emitting ultrasonic waves.

I told Before I want to crate audio out of ultrasound. Please check here up:
Sound from ultrasound - Wikipedia, the free encyclopedia

SSB with carrier is needed to reach less harmonic distortion and get higher efficiency and less bandwidth, Makes sense?

What are you meaning by your last paragraph?

 

[audioguru]

Why the third harmonic will have a higher amplitude than other ones?

A perfect square-wave is symmetrical. Then its even numbered harmonics are very low in amplitude (2nd, 4th, 6th, 8th harmonics etc).
But since the waveform of a square-wave is clipped then it has strong odd numbered harmonics (3rd, 5th, 7th, 9th etc) with the 3rd harmonic the strongest.

 

[wizard]

There is a company that produces high power ultrasonic transmitters that are modulated with speech and a sophistocated algorithm. When the ultrasonic wave strikes an object like a statue in a muzeum then the speech appears to be produced from the statue.

The company claims that the ultrasonics can be modulated with different languages and the modulation can be heard when the beam hits a person. The beams are very directional so people over here can hear one language and people beside them can hear another language.

I don't know if the ultrasonic beams are single-sideband.

Yea, those Emitters do work really audioguru.

Last year I was involved with designing one of those 'Parametric loudspeakers' using almost hundred of ultrasonic sensors as emitters. I amplitude modulated the input signal which actually was a recorded voice via an ultrasonic carrier.
The device was really directional and I was able to hear the voice at more than 330ft distance. When I shined the beam to the celling or to the wall's It seemed that the voice comes directly from That point, so the device was working like a virtual speaker too.
It was an interesting Device.

At the time of working with the said device I was seriously concerned about the effects of 50kHz to 60kHz ultrasonic signals generated by the emitter on human hearing system.