Analyser for acoustic spectral densities - uses eight parallel channel decoders with respective passband filters coupled with logic circuit with integration and summation stages

摘要

An acoustic spectral density integrating circuit comprises a bank of eight pass band filters (41) to (48) which pass frequencies in the bands 50-200, 200-400, 400-800, etc. The filters feed parallel circuits comprising respective rectifying and integration components (5) and (6). Signal levels are monitored in meters (7) prior to application to a ratio circuit (10) where each signal is divided by the sum of the whole eight integrated output to yield measurements on meters (8.1, 8.2, ...8.8) of the proportional frequency content of each pass band. The logic circuit incorporate filters, integrators, voltmeters, a summation unit, an inverter and multipliers.