HUDDLE Test

A huddle test is a metrology procedure that co-locates several sensors so they record the same input at once, isolating each instrument’s self-noise and revealing calibration offsets between units. The shared signal is estimated from the ensemble and subtracted, leaving the residual that quantifies instrument noise; accuracy improves with more reference sensors and a quiet site. The method is standard for seismometers and geophones and is applied to radiometers and other geophysical sensors to cross-check stability before deployment. In polar work it screens ice-mass-balance buoys, thermistor strings, and field radiometers so observing-network data stay comparable across instruments.