The CTBT/IMS infrasonic arrays at both I53US in Fairbanks and I55US in Antarctica have 8 microphones that are laid out in a pentagon-triangle pattern.  Model 5 Chaparral microphones, each with its own Geotech digitizer, are used at each sensor site.  Wind noise-reduction at each microphone site is accomplished using the standard CTBT design of a set of four rosettes of 24 radial pipes vented at the end of each pipe. Further details are given for each site in the links at the left, in addition to details on the Chaparral microphones.