Ultra short wave stereo broadcast signal receiver - has signal demodulated and transposed to ultra short wave band either directly or after modulation on carrier

摘要

The receiver has at least one input and one output frequency changer, and the filtered out channel signals are prepared at the i.f. stage. All channel signals are brought to a common constant level. The i.f. signal, or at least a part of it is demodulated in an f.m. demodulator (9) and the stereo multiplex signal is applied to a filter (13) (low-pass filter and/or absorber circuit), so that the sum signal (L+R, 0-15 kHZ) is transmitted and/or pilot signal suppressed. If signal-to-noise ratio (input signal) is insufficient for stereo reception, the signal selected by the filter (13) is modulated on a carrier and transposed to a channel in the ultra short-wave sound broadcasting band. If the signal to-noise ratio is sufficient, either the non-selected stereo multiplex signal, or the modulated stereo h.f. signal in the i.f. stage is transposed to a channel of the ultra short wave sound broadcasting band.