JPH0711034U - High frequency receiver - Google Patents

Abstract

(57) [Abstract] [Purpose] No malfunction due to nearby interference waves, and the reception frequency does not drift due to temperature changes. A modulated wave signal received by an antenna 11 is high frequency amplified by a high frequency amplifier 13 of a superheterodyne circuit 12, and then converted into an IF signal by a frequency mixer 14 based on a local oscillation frequency signal from a local oscillator 15. To be done. The IF signal from the super-heterodyne circuit 12 is demodulated by the super-reproduction detection circuit 16 composed of the high-frequency oscillation circuit 17 and the quenching oscillation circuit 18, and then the noise component is removed by the low-pass filter 19 to obtain an audio frequency signal. Taken out.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a high frequency receiver, and more particularly to a high frequency receiver for a wireless remote controller used in various keyless systems.

[0002]

[Prior art]

 Generally, a remote controller using radio waves is used for an opening / closing system for doors, shutters, gates, entrances, blinds, etc. of automobiles. Conventionally, as shown in FIG. 2, a high frequency receiver used for such a wireless remote controller is AM-modulated by an antenna 1 by a super regenerative detection circuit 2 composed of a high frequency oscillation circuit and a quenching oscillation circuit. The high frequency signal was demodulated, the noise was removed from the demodulated output by the low pass filter 3, and the voice frequency signal was extracted.

[0003]

[Problems to be solved by the device]

 However, a high-frequency receiver equipped with a conventional super-regenerative detection circuit has a wide allowable range of the reception center frequency, and is very sensitive to interfering waves from other signal sources. There was a problem that the reception center frequency drifted due to aging. An object of the present invention is to provide a high-frequency receiver that does not malfunction due to proximity interference waves and that the reception center frequency does not drift due to temperature changes or the like.

[0004]

[Means for Solving the Problems]

 The present invention is a high-frequency receiver that demodulates a received modulated wave signal by a super-recovery detection circuit and extracts a voice frequency signal through a low-pass filter, based on a local oscillation frequency signal after high-frequency amplification of the received modulated wave signal. A super-heterodyne circuit for converting the signal into an IF signal is connected to the input stage of the super regenerative detection circuit.

[0005]

[Action]

 According to the present invention, the received modulated wave signal is converted into an IF signal by the super heterodyne circuit, and the converted IF signal is demodulated by the super reproduction detection circuit to obtain a desired audio frequency signal.

[0006]

【Example】

 Hereinafter, the high frequency receiver of the present invention will be described in detail with reference to embodiments. FIG. 1 is a block diagram of an embodiment of the high frequency receiver of the present invention. In FIG. 1, 11 is a control high frequency (carrier wave) of 310 MHz transmitted from a remote controller (not shown), which is AM-modulated by an audio frequency signal. An antenna for receiving radio waves, 12 is a super-heterodyne circuit for converting a high-frequency signal received by the antenna 11 into an IF signal, and the super-heterodyne circuit 12 has a high-frequency amplifier 13 for high-frequency amplifying an input modulated wave signal, It is composed of a local oscillator 14 which outputs a local oscillation frequency signal and a frequency mixer 15 which converts the output of the high frequency amplifier 13 into an IF signal of 10 to 20 MHz based on the local oscillation frequency signal. The local oscillator 14 may be composed of an LC oscillator, a crystal oscillator, a SAW resonator, or the like.

Reference numeral 16 denotes a super-reproduction detection circuit that demodulates the IF signal output from the super-heterodyne circuit 12. The super-reproduction detection circuit 16 includes a high-frequency oscillation circuit 17 that oscillates at the reception center frequency when the IF signal is input, and a low-frequency oscillation circuit. And a quenching oscillation circuit 18 which repeatedly oscillates the high frequency oscillation circuit 17 to start and stop the oscillation by intermittently oscillating at the radio frequency. A low-pass filter 19 removes noise such as a quenching frequency from the demodulated output of the superheterodyne circuit 16 and extracts a voice frequency signal.

Next, the operation of the high frequency receiver thus configured will be described. The modulated wave signal as the control wave from the antenna 11 is amplified by the high frequency amplifier 13 of the super-heterodyne circuit 12, and is converted by the frequency mixer 14 into an IF signal based on the local oscillation frequency signal from the local oscillator 15. . The IF signal from the frequency mixer 14 is input to the high frequency oscillation circuit 17 of the super regenerative detection circuit 16, and the high frequency oscillation circuit 17 oscillates at the reception center frequency by the input of the IF signal and also intermittently from the quenching oscillation circuit 18. Demodulation to the received waveform is performed by starting and stopping the oscillation operation based on the oscillation output. The demodulated output of the high-frequency oscillator circuit 17 is input to the low-pass filter 19, and the low-pass filter 18 removes noise such as quenching frequency contained in the demodulated output and outputs an audio frequency signal as a control signal. If the control signal is coded, the output of the low-pass filter is decoded to extract the control code.

[0009]

[Effect of device]

 As is clear from the above description, the high-frequency receiver of the present invention has the super-heterodyne circuit connected in the preceding stage of the super-regenerative detection circuit. This has the effect of preventing the drift of the reception frequency due to temperature changes and the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a high frequency receiver of the present invention.

FIG. 2 is a block diagram of a conventional high frequency receiver.

[Explanation of symbols]

 11 Antenna 12 Super Heterodyne Circuit 13 High Frequency Amplifier 14 Frequency Mixer 15 Local Oscillator 16 Super Regenerative Detection Circuit 17 High Frequency Oscillation Circuit 18 Quenching Oscillation Circuit 19 Low-pass Filter

Claims (1)

[Scope of utility model registration request] 1. A high-frequency receiver that demodulates a received modulated wave signal by a super-reproduction detection circuit and extracts an audio frequency signal through a low-pass filter. The received modulated wave signal is high-frequency amplified to a post-local oscillation frequency signal. A high-frequency receiver characterized in that a super-heterodyne circuit for converting into an IF signal based on the super-heterodyne circuit is connected to an input stage of the super-regenerative detection circuit.