Instrument Response

The KMA network component naming delineates the sensor as follows, the Z-component is used as an example: 

Sensor	Channel	     Rate (Hz)
STS-2	HHZ	       100
	BHZ	        20
	LHZ	         1

SS-1	SLZ	       100
	ELZ	        20

Epi	HGZ	       100
	BGZ	        20

Positive numbers on the Z, N and E channels represent ground motion in the Z, N and E directions.

In the instrument responses given here, the FIR filter coefficients are not presented. The normalized pole-zero responses, calibration factor, and the system pole-zero responses are given. The system pole-zero responses consist of multiplying the constant in the normalized response by the calibration factor. The calibration factor in turn is constructed from the A/D sensitivity and the actual sensor gain.

Sensor Normalized Response Normalized Response Plot Sensor output Digitizer Calib Total Response Total Response Plot
STS-2 sts2.rsp sts2.png 1500 V/m/sec 419460 counts/V 6.29190E+08 counts/m/s asts2.rsp asts2.png
SS-1 ssa.rsp ssa.png 150 V/m/sec 419460 counts/V 6.29190E+07 counts/m/s ass1.rsp ass1.png
Episensor epi.rsp epi.png 40 V/g 419460 counts/V 1.713E+06 counts/m/s/s aepi.rsp aepi.png

Two SHELL scripts work with gsac to plot the responses.
DONRESP plots the normalized responses sts2.rsp, ss1.rsp and epi.rsp. The output figures  are sts2.png, ss1.png and eps.png respectively. DOARESP plots the total responses asts2.rsp, ass1.rsp and aepi.rsp with units of counts/m/sec, counts/m/sec and counts/m/sec/sec, respectively. The output files are asts2.png, ass1.png and aeps.png respectively.

The response plots can be seen by clicking on the respective link in the table.

SAC deconvolution commands


To convert an STS-2 channel to ground velocity in m/sec using gsac or sac2000, the following command is used: 
         transfer from polezero subtype asts2.rsp to none freqlimits 0.005 0.01 10 20

To convert an SS-2 channel to ground velocity in m/sec using gsac or sac2000, the following command is used: 

         transfer from polezero subtype ass1.rsp to none freqlimits 0.05 0.1 10 20

To convert from the Episensor channel to ground acceleration in m/sec/sec, the following command is used: 

         transfer from polezero subtype aepi.rsp to none freqlimits 0.05 0.1 20 40

To convert the resulting acceleration to ground velocity, one next integrated using the SAC command 

         int

The freqlimits option to the transfer command can be adjusted to achieve stability in the deconvolution. The values given in the example are chosen on the basis of the desired frequencies of interest for the 100 sps channel and also the expectation of bands in which there is good signal to noise.

The shell scripts developed for processing KMA data build upon these commands

Last changed January 24, 2007