Grillo Sensor Tests by USGS

Testing of three Grillo sensors in March 2023

Short summary of results from USGS Albuquerque Seismological Laboratory

Tested by: Dr. Adam Ringler, Albuquerque Seismological Laboratory
Report by: Dr. Vaclav Kuna, Grillo Holdings, Inc.

Sensor Self-Noise

Self-noise is approximately -80 dB relative to 1 m/s/s. The vertical axis have slightly higher
self-noise, which is due to differences in the construction of the different sensor axes. Self-noise
is very consistent between sensors.

Figure 1. Self-noise of horizontal X axis of 3 Grillo sensors.

Correlations and timing

A quick test showed correlations of signal among 3 sensors to be greater than 0.9 and
timing to be good relative to the other sensor to 1-2 samples (up to 64 ms). The values are
probably even a bit better but we will need more precise testing for that.

Figure 2. Correlation of horizontal X axis of 3 Grillo sensor’s.

Sensitivity

The sensitivities are well constrained to approximately 100000 counts/m/s/s. All tested
axes are within 3% of each other.

AL ALB01 BNX 99544.7+/-33.7 count/m/s/s
AL ALB01 BNY 99932.4+/-16065.6 count/m/s/s
AL ALB01 BNZ 100911.9+/-8.1 count/m/s/s
AL ALB02 BNX 97200.6+/-5.5 count/m/s/s
AL ALB02 BNY 98384.1+/-10.2 count/m/s/s
AL ALB02 BNZ 100631.1+/-7.4 count/m/s/
AL ALB03 BNX 97280.1+/-17.6 count/m/s/s
AL ALB03 BNY 98866.0+/-8.4 count/m/s/s
AL ALB03 BNZ 100935.1+/-64.2 count/m/s/s
Mean: 100935.1 counts/m/s/s

Range and clip levels

X and Y components are 4 g peak to peak (+-2g), the Z component is 1 g to -2g as it already
registers 1g of normal acceleration.