Single-double sideband filtering and demodulating - converting signal with or without carrier into LF range from IF plane

摘要

The filtering uses an integrated circuit with a combination of an LF low pass filter and a narrow band LF band pass filter, forming a switch-capacitor filter (SKF). The resonance frequency of the band pass filter is slightly above the limit frequency of the low pass filter. The single or two-side band signal is converted into LF range from the IF plane of radio receiver by the SKF scanning. The desired signal side band lies in the pass range of the low pass filter. The carrier lies the pass range of the band pass filter. Both signals are then fed to sync demodulator mixer (M) for desired LF signal generation. ADVANTAGE - Low-cost suppression of disturbed side band.