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Mar 25, 2009, 02:59 AM
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Secrets of sampling


The answer is no. U don't need a 157khz samplerate to capture 40khz sonar. Through the magic of aliasing, U can sample at 50khz. On a 50khz ADC, the 40khz waveform shows up at 10khz. That's good enough for 2" of accuracy. This trick won't work on a soundcard because those have lowpass filters to reject everything above 20khz. Only bare ADC's.

157khz would be better, but we have to pay your mortgages off.

Libusb does indeed support queueing multiple URB's, so U don't need the dual endpoint trick from 7 blogs ago. Getting a 48Mhz PIC to do 3 transducers at 50khz is not easy. Probably not enough room for the radios.

Now page 2.

Most of our memory of Russian Heroine was from just the first 7 months in 2007. Have very sparse memories of her in 2008. Only saw her 4 times in 2009. On the inside, didn't notice the first 7 months receeding into history. They always felt just around the corner, but on the outside the times were getting rarer & we were missing her a lot more.

Having a car & a big salary let her join a lot more activities & keep busy. Before that point, she was pretty idle & unhappy. Those 2 things basically ended the 7 month honeymoon.

The $50,000,000,000,000 man strikes again.

After astronauts installed the final solar arrays on the space station, Osama made up a great line,

"This is really exciting because we're investing back here on the ground (in) a whole array of solar and other renewable energy projects. And so, to find out you're doing this up at the space station is particularly exciting."

Solar panels powering satellites. What a great renewable energy project.
Last edited by Jack Crossfire; Mar 25, 2009 at 03:17 AM.
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