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Resample MHz signal

J

James Barlow

Jan 1, 1970
0
Please excuse me for starting another thread on this topic. My
apologies for not being specific enough the first time. But I did
learn something.

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 program I am using is CoolEdit, which has a built in tone
generator with modulation and eveloping. It can produce 8, 16 or 32
bit resolution at 12 discrete sample rates between 6000 and 192,000.

The idea is to take advantage of this program's functionality and
user-friendly GUI to produce complex signals above the audio range.

PC software (alone) is not a solution as the resulting bandwidth would
be 2KH-2MHz, and therefore beyond the capablities of a standard
soundcard. DSP-based boxes for musicians are equally unsuitable for
the same reason.

I seem to need a lab-type device, or something I can modify or build
from scratch. Do I have any viable options here?

I have Googled big time and so far found nothing. Signal transposers
would be a great project for an electronics magazine. Think of all the
applications.

I hope my aim is clear enough to attract an expert response.

James Barlow.
 
M

MooseFET

Jan 1, 1970
0
Please excuse me for starting another thread on this topic. My
apologies for not being specific enough the first time. But I did
learn something.

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 program I am using is CoolEdit, which has a built in tone
generator with modulation and eveloping. It can produce 8, 16 or 32
bit resolution at 12 discrete sample rates between 6000 and 192,000.

The idea is to take advantage of this program's functionality and
user-friendly GUI to produce complex signals above the audio range.

PC software (alone) is not a solution as the resulting bandwidth would
be 2KH-2MHz, and therefore beyond the capablities of a standard
soundcard. DSP-based boxes for musicians are equally unsuitable for
the same reason.

I seem to need a lab-type device, or something I can modify or build
from scratch. Do I have any viable options here?

I have Googled big time and so far found nothing. Signal transposers
would be a great project for an electronics magazine. Think of all the
applications.

I hope my aim is clear enough to attract an expert response.

Basically what you are after is a DAC that can go up to several MHz.
If the record is fairly short an "arbitrary function generator"
may be good.

Signatec makes some PCI DACs IIRC

Dyneng makes some PC104 ones, I think but they aren't likely fast
enough.

If your computer has an ISA slot doing a home made DAC wouldn't be
very hard. You would want to provide a little bit of buffering FIFO
and self clocking. The timing of writes on a PC is quite jittery.

The easy way to build this would be to make the PC into a "box that
does this function." Basically what I am thinking here is that you do
this part in DOS or Linux and basically take over the whole machine
while you do the output.

On DOS machines that aren't laptops, the 18.2Hz interrupt can be taken
over and can be used to transfer bursts of data at a much faster
rate. Laptops and Windows machines are less likely to be able to do
this. For some reason the BIOSes commonly used in laptops leave the
interrupts off for longish times.

Linus may be able to do it. Windows is extremely unlikely. In both
cases you need to be able to get to the code that sends the burst at
regular times.
 
P

Phil Allison

Jan 1, 1970
0
"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
 
C

colin

Jan 1, 1970
0
James Barlow said:
Please excuse me for starting another thread on this topic. My
apologies for not being specific enough the first time. But I did
learn something.

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 program I am using is CoolEdit, which has a built in tone
generator with modulation and eveloping. It can produce 8, 16 or 32
bit resolution at 12 discrete sample rates between 6000 and 192,000.

The idea is to take advantage of this program's functionality and
user-friendly GUI to produce complex signals above the audio range.

PC software (alone) is not a solution as the resulting bandwidth would
be 2KH-2MHz, and therefore beyond the capablities of a standard
soundcard. DSP-based boxes for musicians are equally unsuitable for
the same reason.

I seem to need a lab-type device, or something I can modify or build
from scratch. Do I have any viable options here?

I have Googled big time and so far found nothing. Signal transposers
would be a great project for an electronics magazine. Think of all the
applications.

I hope my aim is clear enough to attract an expert response.

a video card has a dac that will go upto 200mhz+ wich you can use.

I dont know how to do it myself exactly but ive read about it being done and
considered doing it myself a few times.

for a repetative pattern its probably quite easy.

you have to set the video timings so you dont get blanking etc,
and put your output into the video display memory.

ofc you wont be able to use your display at the same time,
unless you have a seperate vga adaptor.


COlin =^.^=
 
B

Bob

Jan 1, 1970
0
"James Barlow"

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

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

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.
Frequency shifting the audio band up into the supersonic region is easily
possible with analogue circuitry

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
 
P

Phil Allison

Jan 1, 1970
0
"Bob"
"Phil Allison"
I'm guessing that you want to send the resulting signal through the
air.

** A very wild guess indeed.

Many audio applications can loose the bass without anyone caring.


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

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


** 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
 
N

Nobody

Jan 1, 1970
0
a video card has a dac that will go upto 200mhz+ wich you can use.

The DAC is only 8-bit, which may not be enough for the OP.

If it is, then a video card gives you 3 x 200MHz+ DACs for a fraction of
the cost of the same thing sold as "test equipment".
I dont know how to do it myself exactly but ive read about it being done and
considered doing it myself a few times.

for a repetative pattern its probably quite easy.

you have to set the video timings so you dont get blanking etc,

Not all hardware supports this. There's invariably a fixed upper limit on
the number of pixels per line (determined by the number of bits in the
corresponding register), and you can't always reduce the blanking to zero
(the horizontal blank may be used to refresh DRAM).

Also, if you want to program the video hardware yourself, getting
documentation for modern video chips is far from straightfoward. Even
with the documentation, programming is far from straightfoward. If you
can get something from before the era of hardware 3D, it will be a lot
simpler.
 
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