Measuring ELFs of 8Hz

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JulianLee
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Measuring ELFs of 8Hz

Post by JulianLee » Sun May 14, 2006 10:55 am

Hi there.

I'm looking to conduct an amateur experiment to detect ELF magentic fields. A precedent experiment I'm looking to replicate discovered output of variable frequency 0.3Hz-30Hz, centred around 7-8Hz.

Output will be in voltage, I expect in the range +-5v, but I suppose this could be adjusted using an amplifier.

I'm looking at the ADC-20/24, but I heard that the maximum sampling rate is 17.7Hz, which makes for a maximum frequency of 8.8Hz... (is that correct?)

What would happen if the frequency of my output is lower, would the acquirer simply not be able to pick it up?

If the frequency does fall below the range, would the acquirer still be able to measure the magnitude of the output (which is more important for me) if not its exact frequency?

If not, do you have any equipment which would be more suitable for detecting output in the range?

Thanks for your help!

Julian

Michael
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Post by Michael » Mon May 15, 2006 8:47 am

Hello Julian,

The ADC20/24 is primarily a data logger. I do not feel it is suitable for your application. Please consider our oscilloscope rangeof instruments. They will cover the voltage and frequency ranges you are looking for.

Please visit: http://www.picotech.com/oscilloscope-sp ... tions.html

Best regards,
Michael
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Julian

More questions

Post by Julian » Mon May 15, 2006 12:10 pm

Hi Michael,

Thanks for your reply. I'd need 16 bit or higher, so it looks like the ADC-216 would be most suitable. I don't have much experience with this, so could you please confirm for me that it could do the following:

Record an oscillating voltage input in a +/- 10V range (if that is too high, what would be a better range for me to adjust to?), which is unlikely to be a neat sine wave
Work with variable frequencies in the range 0.5Hz-30Hz


Also, are you able to offset a fixed component out from the input before taking measurements?


Thanks,

Julian

Michael
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Post by Michael » Mon May 15, 2006 12:38 pm

Hello Julian,

Thanks for the reply.

OK, the 216 has a max ±20V input range. So your signal level should be fine.

The range of the unit is 166kHz, again well within the spec you quoted.

Best regards,
Michael
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