Simplifed Transistorized FM Magnetic Tape System for Recording Ground Vibrations

Circuitry is described for multiple-channel FM recording, on magnetic tape, of continuous or transient ground vibrations in the frequency range 5-800 cps. Special features include: continuous amplitude and time calibration of each channel of the recording and playback system, origin-time recording on each channel for use with impact sources of vibration, provision for readout on a direct-writing recorder with restricted high-frequency response, provision for variable band-pass filtering.