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4. 发明专利

GB2111335A A method of tuning an AM receiver 未知
公开(公告)号：GB2111335A
公开(公告)日：1983-06-29
申请号：GB8232883
申请日：1982-11-18
申请人： PIONEER ELECTRONIC CORP
发明人： MORI IWAO
IPC分类号： H03J1/00 , H03J7/06 , H03J7/18
摘要： The proposed change in LW broadcast frequency allocation systems will result in a transition period during which broadcasts may occur under the old or the new system. Switching to deal with reception of either the old or the new system will therefore be required. The old and new frequency allocation systems have frequency spacings of (kn+l) kHz and (kn) kHz respectively, where k and l are constants and n is a positive integer. This invention provides a method of tuning an AM receiver capable of automatically tuning at a frequency interval of kn+l kHz in accordance with a channel plan, characterized in that while receiving a frequency at the interval of kn+l kHz, the level of a field intensity signal at (kn+l kHz)-l kHz is detected and compared with the level of a field intensity signal at (kn+l) kHz, and the receiver is tuned to the frequency providing the higher field intensity signal level.

7. 发明专利

JPS60134632A AM RECEIVER 失效
公开(公告)号：JPS60134632A
公开(公告)日：1985-07-17
申请号：JP24211983
申请日：1983-12-23
申请人： PIONEER ELECTRONIC CORP
发明人： MORI IWAO
IPC分类号： H04B1/16
摘要： PURPOSE:To eliminate noise and to improve the S/N by inserting a low-pass filter between an AM detecting stage and a low frequency amplifier stage when an output of a DC level detector is the 1st prescribed time or below and inserting an attenuator to the pre-stage of a high frequency amplifier stage when the output is the 2nd prescribed value or over exceeding the 1st prescribed value so as to set the 1st automatic gain control circuit into the operating state. CONSTITUTION:When a DC voltage level detected by a DC level detector 16 is a level 1 or below, a control circuit 17 controls a switch 19 so as to insert a low-pass filter 18 to a line via a driver 22. Then the low-pass filter 18 is inserted between the low-pass filter 8 and a coupling capacitor 9. Thus, a high frequency noise superimposed on a signal when a weak input station is received is eliminated by the low-pass filter 18 so as to improve the S/N. In case of a strong input level, the input is attenuated by an attenuator 11 so as to receive a signal without distortion even at a strong input exceeding normal automatic gain control AGC range.

8. 发明专利

JPS5885623A TUNING METHOD OF AMPLITUDE MODULATION RECEIVER 失效
公开(公告)号：JPS5885623A
公开(公告)日：1983-05-23
申请号：JP18362981
申请日：1981-11-18
申请人： PIONEER ELECTRONIC CORP
发明人： MORI IWAO
IPC分类号： H03J1/00 , H03J7/06 , H03J7/18
摘要： PURPOSE:To eliminate troublesomeness for switching and deterioration of characteristics, by providing an automatic circuit which is capable of receiving a broadcast of a broadcasting station whose channel has been selected by a channel plan of 9nKHz, in an AM receiver which is automatically tuned by a 9n+ 2KHz step. CONSTITUTION:When a microprocessor 9 has scanned at a frequency interval of 9n+2KHz, and has stopped scanning by detecting electric field intensity exceeding a prescried level, a receiving instruction of 9nKHz is generated continuously. By this receiving instruction of 9nKHz, an FET12 becomes an on-state, and an electric field intensity signal is sample-held. Output of a sample-holding circuit A consisting of an FET10 and a capacitor 11, and a sample-holding circuit B consisting of the FET12 and a capacitor 13 are compared by a level comparator 14, an output of the level comparator 14 is waveform-shaped 15, is outputted to the microprocessor 9, and a larger one of the outputs of the sample-holding circuit A and B, that is to say, that which has larger electric field intensity is selected. In this way, 9n+2KHz and 9nKHz are switched automatically.

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