JPS596614A - Automatic adjusting device of received frequency - Google Patents

Abstract

PURPOSE:To adjust received frequency precisely with a simple constitution by providing the titled device with a circuit for outputting a signal having the frequency corresponding to receiving frequency lagged by the frequency of a normal intermediate frequency signal from the oscillation frequency of a local oscillating circuit. CONSTITUTION:A required signal is applied to a control terminal 1 to actuate a motor control circuit 13, an intermediate frequency oscillator 15 and a mixing circuit 16 respectively. Consequently, the mixing circuit 16 mixes the output of the intermediate frequency oscillator 15 with the output of the local oscillating circuit 8 and outputs a high frequency signal having the frequency equal to the received frequency. Under said status, a switch 2 is turned off, said high frequency signal is applied to the receiver and an output obtained from an intermediate frequency amplifier circuit 9 and a wave detecting circuit 10 is applied to a level detecting circuit 12. In addition, a motor driving circuit 13 is controlled so that each output shows its peak value and the capacitance value of a variable capacitor 4 is adjusted by a motor 14 so that precise receiving frequency is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic reception frequency adjustment device used in super-hetero gain type radio receivers, etc. The present invention relates to an automatic reception frequency adjustment device that is capable of accurately adjusting the reception frequency with a simple configuration. The object is to provide an adjustment device.

Generally, a superheterodyne radio receiver is configured to convert a signal received by an antenna into an intermediate frequency signal using the output of a local oscillation circuit, and then perform detection. Therefore, the reception frequency is determined by the oscillation frequency of the local oscillation circuit, and there is usually no need to provide any additional circuit to the high frequency tuning circuit. however,
It is extremely difficult to accurately adjust the receiving frequency in a radio receiver for receiving shortwave broadcasting, so a variable capacitor for fine adjustment is separately installed in the high frequency tuning circuit, and this is manually operated to obtain an accurate tuning point. I have to. However, with this type of device, the operator has to make adjustments by hand while looking at a meter for tuning instructions, which makes the operation cumbersome and extremely difficult to obtain an accurate tuning point. be.

The present invention eliminates the conventional drawbacks as described above, and provides an excellent automatic receiving frequency adjustment device that can easily and accurately adjust the receiving frequency with a simple configuration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The automatic reception frequency adjustment device of the present invention will be described below with reference to drawings of an embodiment. In the figure, 1 is an antenna input terminal, 2 is a switch, 3 is a coil constituting a high frequency tuning circuit, 4 is a variable capacitor, 6 is a coupling capacitor, 6 is a high frequency amplifier circuit, 7 is the output of the high frequency amplifier circuit 6 and local oscillation 9 is an intermediate frequency amplifier circuit, 10 is a detection circuit, and 11 is a detection circuit 1.
0 is an output terminal, 12 is a level detection circuit which receives the output of the intermediate frequency amplifier circuit 9 and the output of the detection circuit 1Q, and 13
14 is a motor drive circuit controlled by the output of the level detection circuit 12; 14 is a motor controlled by the output of the motor drive circuit 13 to change the volume value of the variable capacitor 4;
16 is an intermediate frequency oscillator that generates an output with a frequency equal to the regular intermediate frequency, 16 is a mixing circuit that receives the output of the intermediate frequency oscillator 15 and the output of the local oscillation circuit 8, and 17° and 18 are the outputs of the mixing circuit 16. This is the wave filter and capacitor that supplies the antenna input circuit.

Incidentally, the motor control circuit 13. Both the intermediate frequency oscillation circuit 16 and the mixing circuit 16 are configured to become operational only when a required signal is supplied to the control terminal 19.

In the above embodiment, when the switch 2 is turned on and the signal applied to the antenna input terminal 1 is applied to the high frequency amplifier circuit 6 via the high frequency tuning circuit, its output is mixed with the output of the local oscillation circuit 8 in the mixing circuit 7. and converted into an intermediate frequency signal. Since the intermediate frequency signal is amplified by the intermediate frequency amplification circuit 9 and detected by the detection circuit 10, a required low frequency output can be taken out at the output terminal 11.

In this case, the reception frequency can be easily changed by changing the oscillation frequency of the local oscillation circuit 8. However, it is extremely difficult to completely fine-tune the reception frequency when receiving shortwave broadcasts. In such a case, a required signal is applied to the control terminal 19, and the motor control circuit 13° intermediate frequency oscillator 16. The mixing circuits 16 are respectively put into operation. In this way, the output of the intermediate frequency oscillator 16 and the output of the local oscillation circuit 8 are mixed together in the mixing circuit 16, and a high frequency signal having a frequency equal to the receiving frequency is output. Therefore, in this state, the switch 2 is turned off, and this is applied to the high frequency amplifier circuit 6 via the high frequency tuning circuit. In this way, the high frequency signal and the output of the local oscillation circuit 8 are mixed in the mixing circuit 7, and an intermediate frequency signal corresponding to the difference is output. Then, this intermediate frequency signal is amplified by the intermediate frequency amplification circuit 9 and detected by the detection circuit 10 as before.

The output of the intermediate frequency amplification circuit 9 and the output of the detection circuit 1o are truly applied to a level detection circuit 12, where their levels are detected. If the detected level is below a predetermined value, a predetermined output is desired from the level detection circuit 12, thereby controlling the motor drive circuit 13 and driving the motor 14. Therefore, the capacitance value of the variable capacitor 4 changes as the motor 14 is driven, and the intermediate frequency amplification circuit 9 and the detection circuit 1
The output of ° is controlled to the peak value. When the outputs of the intermediate frequency amplifier circuit 9 and the detection circuit 10 exceed a predetermined value and show a peak value, the operation of the motor drive circuit 13 is stopped, thereby completely adjusting the receiving frequency. Therefore, by stopping the application of the control signal to the control terminal 19 and turning on the switch 2 in this state, the reception signal can be accurately received.

As is clear from the above embodiments, the automatic reception frequency adjustment device of the present invention allows accurate adjustment with a simple configuration, is easy to operate, and is extremely advantageous in practice.

In the embodiment, the high frequency tuning circuit is composed of a coil 3 and a variable capacitor 4, and this capacitor 4 is connected to the motor 14.
However, the above capacitor 4
Instead, a variable capacitance diode or the like may be used and the voltage applied thereto may be controlled. Further, in the embodiment, an intermediate frequency oscillator 15 and a mixing circuit 16 are added, and the output of the intermediate frequency oscillator 16 and the output of the local oscillation circuit 8 are respectively applied to the mixing circuit 16 to obtain a high frequency signal equal to the receiving frequency. However, it goes without saying that it is also possible to add a PLL oscillator or the like separately and thereby obtain a high frequency signal equal to the direct reception frequency.

[Brief explanation of the drawing]

The figure is a block diagram of an embodiment of the automatic receiving frequency adjustment device of the present invention. 1... Antenna input terminal, 2... Switch, 3... Coil, 4... Variable capacitor, 6... Coupling capacitor, 6.・・・・・・
High frequency amplifier circuit, 7...Mixing circuit, 8...
...Local oscillation circuit, 9...Intermediate frequency amplification circuit,
10...Detection circuit, 11...Output terminal, 12...Level detection circuit, 13...
Motor drive circuit, 14...Motor, 16...
...Intermediate frequency oscillator, 16...Mixing circuit, 1
7... Mud wave device, 18... Capacitor, 1
9... Control terminal.

Claims (1)

[Claims] A circuit is provided that outputs a high frequency signal with a frequency corresponding to the reception frequency that is shifted by the frequency of the regular intermediate frequency signal with respect to the oscillation frequency of the local oscillation circuit, and the output of this circuit is transmitted to the local oscillation circuit through the high frequency tuning circuit. The oscillation output of the oscillation circuit is applied to the mixing circuit, and the high frequency tuning circuit is controlled by the output of the level detection circuit which receives the intermediate frequency output so that the output level of the intermediate frequency signal obtained by the mixing circuit shows a peak value. An automatic receiving frequency adjustment device configured to automatically control the tuning frequency.