Title:
VOICE SQUELCH CIRCUIT
Document Type and Number:
Japanese Patent JP3124331
Kind Code:
B2
Abstract:
PURPOSE: To reduce the effect of another telegraphic wave or FSK (Frequency Shift Keying) modulation wave or the like onto the demodulation voice output of a radio receiver.
CONSTITUTION: This voice squelch circuit provided to a detection output of a radio receiver is provided with a discrimination circuit 4 discriminating whether or not the pitch frequency of a demodulation signal detected by a pitch detector 1 is within the range of human voice frequencies, a comparator 5 receiving the detection outputs of detectors 2, 3 detecting respectively the energy of a low frequency band and that of a high frequency band of a demodulation signal and outputting a signal representing whether or not the signal is a voice signal, and with an integration discrimination circuit 7 ANDing the output of the comparator 5 and the output of the discrimination circuit 4 to average the result and outputting a signal representing whether or not the output of the circuit 7 indicates the presence of the voice signal.
Inventors:
Mitsuhiko Kitajima
Application Number:
JP27350691A
Publication Date:
January 15, 2001
Filing Date:
September 26, 1991
Export Citation:
Assignee:
Hitachi Kokusai Electric Co., Ltd.
International Classes:
H04B1/10; (IPC1-7): H04B1/10
Domestic Patent References:
| JP6035797A | ||||
| JP627224A | ||||
| JP5941936A |
Attorney, Agent or Firm:
Manabu Otsuka