Re: Resample MHz signal

Phil Allison 18 years ago

"James Barlow"

> What I am really looking for is external hardware that will allow me
> to upload an audio frequency WAV file, such a voice or music, from a
> PC and then play it back at 100 times the original sample rate.
>
> The idea is to take advantage of this program's functionality and
> user-friendly GUI to produce complex signals above the audio range.

** Which will NOT be the case with a 100 times increase.

eg 50Hz x 100 = 5000 Hz = very audible.

You are obviously a clueless jerk on a fool's errand.

God knows what crackpot idea you have in mind but will not tell us.

Frequency shifting the audio band up into the supersonic region is easily possible with analogue circuitry, but will not compress time duration of course.

....... Phil

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Bob 18 years ago

I'm guessing that you want to send the resulting signal through the air. All the ultrasonic transducers I have read about have a resonant point and the frequency response drops either side of it. There are some with -6dB points at around 50% and 150% of the resonant frequency but I'm not aware of any with multi-octave response. Anyone?

Perhaps a combination of frequency shfiting and frequency multiplication might be more practical eg shift 300Hz-10000Hz to 40300-50000 then play back 44 times faster to get a signal about 400KHz wide centred on 1.98MHz.

Perhaps do the frequency shift mathematically into a 192KHz PCM .wav file then a DAC running at just over 8Msample/sec.

Getting data out of a PC that fast is not that easy. I'd be thinking of an ethernet device with some buffering but that's mainly because I view low level drivers as a horrific thing to take on.

Many audio applications can loose the bass without anyone caring. The tiny loudspeakers in my laptop do nothing below 300Hz.

For voice you can get away with 300-3300hz though up to 8000hz helps intelligabilty.

The simplist approch, mixing with 40Khz produces a voice signal at 40300-43300 and an inverted voice signal at 39700-36400

An analog signal that avoids that seems to involve messing with a multi-octave 90degree phas shifter.

Bob

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Phil Allison 18 years ago

"Bob" "Phil Allison"

** A very wild guess indeed.

** The OP has stated he wants good waveform accuracy.

** For which low cost, easy to build, published designs exist.

Including one from me in the August '97 issue of Electronics Australia magazine.

( 22Hz to 20 kHz , +/- 2 degrees ) as part of a + 5Hz shifter for acoustic feedback suppression.

....... Phil

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