Apatity infrasound array
Three microbarographs Chapparel Model V had been installed near the sensors of inner circle of Apatity seismic array. The microbarographs data are transmitted to data collection point. There the data are digitized by RD-6 analog-to-digit convertor (Nanometrics) which is also used for seismic data digitizing (old system). But RD-6 includes a highpass filter so we made a new system based on L-1221 ADC. Data of both systems are transmitted in Apatity by radio modems where they are processed and stored.
The microbarographs are placed into waterproof bunkers. Each sensor connected to a fan pipe filter which suppressed wind noise (see pictures below).