Counts in Swarm

Technical Support
1

I was using Raspberry shake 1D and reading the data from Swarm (y-axis read ‘Counts’). I was trying to compare the data with the data mentioned in the ‘SpecificationsforRaspberryShakeV4’. In that file, it shows that the sensitivity is 3.81E+08 counts/m/s. Is it same as what we read on swarm without calibration and if not then how can we get this value? At what frequency were these values measured?
I want to confirm that the -3dB point that it mentions as 0.7Hz and 29Hz, does it means that the geophone is subjected to 0.7Hz and 29Hz vibration using a shaker table?

specification
specification663×815 55.3 KB

2

Hello tchauhaun6, and welcome to our community!

To answer your questions, point by point:

In that file, it shows that the sensitivity is 3.81E+08 counts/m/s. Is it same as what we read on swarm without calibration and if not then how can we get this value?
  • Here sensitivity is the overall gain of the system. This is the multiplier used to compare one Make/ Model of seismograph to another. When multiplied by the raw data (which is in counts), it returns true ground motion in meters/second.
At what frequency were these values measured?
  • The sensitivity was measured at 5 Hz, or in the middle of the “flat” portion of the instrument response curve.
I want to confirm that the -3dB point that it mentions as 0.7Hz and 29Hz.
  • You will need a Shake Table and sophisticated software to verify the sensitivity, poles and zeros.
does it means that the geophone is subjected to 0.7Hz and 29Hz vibration using a shaker table?
  • This is not very clear. The two frequencies you have listed are the -3dB points, or where the instrument response is no longer “flat”. If you can expand a bit I could try to provide more info regarding what you need.

Thank you for your interest!

1 Like
3

Thank you Stromchaser, my doubts are cleared.
I have one more question regarding the sleeman self noise mentioned in the datasheet. Is it just for the digitizer or the whole system?
And how do you calculate the amplitude in the y-axis.

4

No problem at all tchauhan6, happy to help!

For your question in the last message, the Sleeman self-noise is referred to the whole system, which is then consequently plotted in the charts that are available on our Technical Specification sheet (if anyone else reading this topic is interested): https://manual.raspberryshake.org/_downloads/RSGlobalTechnicalSpecificationsDocument.pdf