JPH0438614Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a novel receiver adjustment point detection device used for adjusting a receiver such as a radio receiver.

BACKGROUND ART Conventionally, when adjusting an electric circuit element that is included in a radio receiver and is to be adjusted, a high frequency signal modulated by a low frequency signal that is an audio signal is input to the radio receiver. The smaller the level, the less saturation will occur at the adjustment point, allowing for more accurate adjustment. However, in reality, if the high-frequency signal level is small, changes in the output signal of the radio receiver cannot be accurately captured due to the influence of the nozzle at a position that is off the adjustment point. I have no choice but to increase it and make adjustments.

Therefore, in the past, when the adjustment point of a radio receiver is shifted, the level of the high-frequency signal input to the radio receiver is increased to reduce the influence of noise contained in the output signal of the radio receiver, and the electric circuit The elements are being adjusted. The output signal level of the radio receiver saturates near the adjustment point, so in order to prevent saturation, the operator must vary the high-frequency signal level to reduce it and lower the output signal level near the adjustment point. It is.

In order to reduce the influence of noise and adjust the electrical circuit elements of the radio receiver, the output signal of the radio receiver is passed through a bandpass filter and only that output signal is captured.
Adjustments will readily occur to those skilled in the art. That is, a radio receiver is given a high frequency signal modulated by a low frequency signal of a predetermined frequency, for example 1kHz, and the output signal from the radio receiver is the low frequency signal of 1kHz, and the bandpass filter is , which has the characteristic of passing only this 1kHz low frequency signal. Generally, if a filter is a passive filter, it is constructed by combining a resistor R, a coil L, and a capacitor C.
An active filter using an operational amplifier or the like is constructed by combining a resistor R and a capacitor C, thereby limiting the frequency pass band. Therefore, in a filter, there is always a signal response delay due to the coil L and capacitor C, and the output signal of the filter is delayed by the response delay time τ compared to the input signal of the filter. This response delay time τ increases as the amount of attenuation of the filter increases, that is, as the order of the filter formed by the coil L and the capacitor C increases.

Therefore, in order to reduce the influence of noise,
When the order of the bandpass filter is increased, the response delay time τ increases, for example, τ=0.1 seconds. Therefore, when the electric circuit element to be adjusted is adjusted and the level of the output signal from the radio receiver reaches the adjustment point where it reaches the maximum point, the output signal from the radio receiver passes through the bandpass filter. A large response delay time τ occurs before the output is output from the adjustment monitor, and during that time τ the operator continues to adjust the electric circuit element, thereby causing the electric circuit element to e.g. When using a trimmer capacitor, a problem occurs in which the operator uses a screwdriver or the like to turn the trimmer capacitor too far from the adjustment point.

Purpose The purpose of the present invention is to provide a receiver adjustment point detection device that allows adjustment of electric circuit elements included in a receiver such as a radio receiver easily and accurately. It is.

Means for Solving the Problems The present invention is a receiver adjustment/inspection detection device that applies a high-frequency signal of a predetermined frequency to a receiver including an electric circuit element to be adjusted and displays the output from the receiver. , a high-frequency signal generator that generates a signal in which a high-frequency signal of a predetermined frequency to be received by a receiver including an electric circuit element to be adjusted is modulated with a low-frequency signal of a predetermined frequency, and supplies the signal to the receiver; a detection means for detecting the output level of the low frequency signal after demodulation of the receiver; a display means for displaying the output of the receiver; a bandpass filter that selectively passes a low frequency signal included in the output of the demodulator and has a variable attenuation amount in a frequency band other than the low frequency signal; , when the output level after demodulation of the receiver is small, the attenuation amount of the bandpass filter is increased, and when the output level after demodulation of the receiver is large, the attenuation amount of the bandpass filter is decreased. This is an adjustment point detection device for a receiver, characterized in that it includes a control means for controlling.

As described above, according to the present invention, the high frequency signal generator modulates a high frequency signal of a predetermined frequency with a low frequency signal having a predetermined frequency, for example, 1 kHz, and the modulated high frequency signal obtained in this way is is applied to a receiver such as a radio receiver, the receiver receives and demodulates a modulated high frequency signal from a high frequency signal generator, and derives the demodulated low frequency signal, and the detection means , detect the output level of the low frequency signal from the receiver. The low frequency signal from the receiver is given to the display means via a bandpass filter, and this bandpass filter selectively passes the demodulated low frequency signal output from the receiver, and displays the low frequency signal. In a frequency band other than the signal, the signal applied to the bandpass filter is attenuated, and the amount of attenuation is variable.

In the control means, in response to the detection output from the detection means, when the level of the output, which is a low frequency signal of the demodulator of the receiver, is small, that is, the level of the output, which is a low frequency signal of the receiver demodulator, is adjusted. When an electric circuit element, such as a trimmer capacitor, deviates significantly from the optimum adjustment point, the attenuation amount of the bandpass filter is increased. By increasing the amount of attenuation in the frequency band other than the low-frequency signal of the bandpass filter, the influence of noise contained in the output from the radio receiver at a position far away from the adjustment point can be reduced, and the adjustment can be made. It becomes easier. Increasing the amount of attenuation in a frequency band other than low frequency signals of a bandpass filter means, for example, increasing the order of the bandpass filter, which increases the response delay time τ. However, at a position deviated from such an adjustment point, even if the response delay time τ is large, it will not interfere with the adjustment work of the electric circuit elements.

The control means, in response to the detection output from the detection means, reduces the amount of attenuation in a frequency band other than the low frequency signal of the bandpass filter when the level of the output which is the low frequency signal after demodulation of the receiver is large. do. Reducing the attenuation amount of the bandpass filter means, for example, decreasing the order of the bandpass filter, and thereby reducing the response delay time τ of the bandpass filter.
becomes smaller. Therefore, while adjusting the electrical circuit elements, the operator can watch the output of the receiver on the display means and stop the adjustment when the output level of the receiver reaches its maximum. This makes it possible to accurately adjust the electric circuit elements, and eliminates the problem of overstepping the adjustment point when adjusting the electric circuit elements, as described in connection with the prior art described above. In this invention,
Does not occur.

Note that the output after demodulation of the receiver generally contains noise over the entire frequency band, and even near the adjustment point where the level of the output, which is a low frequency signal after demodulation of the receiver, is high, This noise is always included, and when it is near this adjustment point, the amount of attenuation in the frequency band other than the frequency of the low frequency signal becomes small in the bandpass filter as described above, and therefore the display means Although the signal applied to the signal contains noise over such a wide frequency band, the output level of the low-frequency signal is high, so its SN
The ratio is good. Therefore, the operator can accurately adjust the circuit elements.

Embodiment FIG. 1 is a block diagram showing the electrical configuration of an embodiment of the present invention. The output signal of the high frequency signal generator 1 is a signal obtained by modulating a high frequency signal of a predetermined frequency with a low frequency signal having a predetermined frequency, for example, 1 kHz, and this signal
is given to the radio receiver 2 via. The output signal sent from the line l2 of the radio receiver 2 is a low frequency signal having a frequency of 1 kHz after receiving and demodulating the high frequency signal from the high frequency signal generator 1. , and is formatted by the output receiving section 3. The output signal of the output receiving section 3 is given to the comparing section 4 via line l3, and the comparing section 4
Then, the output signal level is compared with a preset reference voltage level. In comparison section 4,
A signal corresponding to the level difference between the output signal and the reference voltage is sent to the control unit 5 via the line l4.
give to The control section 5 is connected to a bandpass filter 6 via a line l5, and the comparison section 4
In response to the output signal from the bandpass filter 6, the attenuation amount of the bandpass filter 6 is varied, in other words, the low frequency signal is selectively passed through, and the attenuation amount in a frequency band other than the low frequency signal is made variable.

From the output line l2 of the radio receiver 2, the second
A signal P1 as shown in FIG. 1 is sent out and applied to the bandpass filter 6. The attenuation characteristics of the bandpass filter 6 are shown in FIG. FIG. 2 shows the line l displayed on the adjustment monitor 7 when the output of the line l7 is applied to the adjustment monitor 7.
7 is a diagram showing the output level of No. 7 corresponding to the adjustment position of the trimmer capacitor. The radio receiver 2 includes an electric circuit element to be adjusted in its tuning circuit, and this electric circuit element is, for example, a trimmer capacitor, and the horizontal axis of FIGS. The adjustment position of the trimmer capacitor is shown, with reference mark B indicating the optimum adjustment point and reference mark A indicating a position shifted from the adjustment point B. Second
The output P1 derived from the radio receiver 2 in FIG. 1 via line l2 includes the demodulated low frequency signal s1 and noise n1 having a substantially constant level over the entire frequency band, The sum of such low frequency signal s1 and noise n1 is
The output is P1.

The characteristics of the bandpass filter 6 will be explained with reference to FIG. The horizontal axis of Fig. 2 represents the frequency,
The vertical axis represents the amount of attenuation of the bandpass filter 6.
This bandpass filter 6 is configured such that at frequency 0 (1 kHz in this embodiment) of the resistive frequency signal,
The low frequency signal is selectively passed through, and the amount of attenuation in the frequency band other than the low frequency signal is a1,
It is variable as shown by a2 and a3. In order to increase the attenuation amount of the bandpass filter 6 in the order of a3, a2, and a1, it is necessary to increase the order of the filter in that order, and in this case, the response delay time τ of the bandpass filter 6 increases in that order. .

When adjusting the trimmer capacitor provided in the radio receiver 2, the output level from the radio receiver 2 is small at the adjustment position A shown in FIG.
is controlled so that the amount of attenuation in the frequency band other than the low frequency signal in the bandpass filter 6 becomes large as shown by the attenuation characteristic a1 in FIG. Therefore, at adjustment position A, which is outside adjustment point B, the influence of noise is reduced and the radio receiver 2
selectively passes only the low frequency signal from the low frequency signal.

The bandpass filter 6 having the attenuation characteristic a1 with a large amount of attenuation has a high filter order, which results in a large response delay time τ. Since the position of the trimmer capacitor provided in the radio receiver is greatly deviated from adjustment point B, the operator must check if the adjustment position of the trimmer capacitor provided in the radio receiver is past adjustment point B. There's no way you'll end up with it.

When the operator adjusts the trimmer capacitor and the adjustment position approaches adjustment point B, the level of the low frequency signal output from the radio receiver 2 increases, and in response to this, the control unit 5 adjusts the bandpass filter. The attenuation characteristic of No. 6 is made smaller as shown by reference numeral a2 in FIG.

Furthermore, when the adjustment position of the trimmer capacitor of the radio receiver 2 approaches the adjustment point B and the level of the output of the low frequency signal from the radio receiver 2 increases, the control section 5 controls the adjustment of the bandpass filter 6. The damping characteristics are indicated by reference numeral a in Fig. 2.
As shown in 3, reduce the amount of attenuation. In this way, by reducing the amount of attenuation of the band pass filter 6, the filter order of the band pass filter 6 is reduced, and thereby the response delay time τ is reduced, for example. τ=0.02 seconds. Therefore, while the operator is adjusting the trimmer capacitor, at position B where the output of the adjustment monitor 7 is maximum as shown in FIG.
The adjustment operation can be stopped and thus at the adjustment point B of the trimmer capacitor, the adjustment can be stopped. At and near this adjustment point B, the output level of the low frequency signal derived from the radio receiver 2 is high, and therefore the SN ratio is large, so the amount of attenuation in the frequency band other than the low frequency signal of the bandpass filter 6 It is possible to accurately adjust the trimmer capacitor to the adjustment point B even if the value is small.

FIG. 2 3 shows the line l of the bandpass filter 6.
7 is a graph showing the relationship between the output level and the adjustment position of the trimmer capacitor. In the output from the bandpass filter 6, the level of the low frequency signal is high at adjustment point B, and the level of the low frequency signal is displayed low at position A, which is shifted from the frequency of 1 kHz of the low frequency signal. Therefore, the operator should check the line l7 displayed by this adjustment monitor 7.
It is sufficient to stop the adjustment work when the adjustment point B at which the maximum output level is obtained is obtained while checking the output level. Therefore, like point B in Figure 2,
With the attenuation amount of the bandpass filter 6 reduced as shown in a3, the operator can use the line l8 for convenience of illustration with a signal without response delay caused by the filter 6.
As shown in the figure, the circuit adjustment of the radio receiver 2 can be performed.

In this way, the output signal level of the radio receiver 2 is monitored by the comparator 4, the attenuation amount of the bandpass filter 6 is automatically varied, and the output level can be displayed on the adjustment monitor 7.

In FIG. 2 described above, the attenuation characteristics a1, a2, and a3 of the bandpass filter 6 are shown to have the same attenuation amount at frequency 0 of the low frequency signal; a2,a
The amount of attenuation at frequency 0 may be different for each frequency 0, and the operator can display the attenuation amount on the adjustment monitor 7 through the bandpass filter 6 having the characteristic a3 near the adjustment point B of frequency 0. All you have to do is adjust the trimmer capacitor so that the output level is maximized.

The present invention can be implemented to adjust not only the trimmer capacitor of the radio receiver 2, but also other electric circuit elements such as a volumetric volume and a coil core.

Effects of the invention As described above, according to the invention, when the output level of the low-frequency signal after demodulation of the receiver is small, the attenuation amount of the bandpass filter is increased, and the output of the low-frequency signal after demodulation of the receiver is increased. By reducing the amount of attenuation of the bandpass filter when the amount of attenuation is large, the adjustment position of the electric circuit element deviates from the adjustment point, and when the output level is small, there is no adverse effect due to noise, so the high frequency signal level given to the receiver can be reduced. No need to increase. Thus, according to the present invention, it becomes possible to easily and accurately adjust a receiver such as a radio receiver.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the electrical configuration of an embodiment of the present invention, and FIG. 2 is a diagram for explaining the operation of the configuration shown in FIG. 2...Radio receiver, 3...Output receiving section, 4...
...Comparison section, 5...Control section, 6...Band pass filter.

Claims (1)

[Claims for Utility Model Registration] A receiver adjustment point detection device that applies a high-frequency signal of a predetermined frequency to a receiver including an electric circuit element to be adjusted and displays the output from the receiver, which A signal obtained by modulating a high frequency signal of a predetermined frequency with a low frequency signal of a predetermined frequency to be received by a receiver including an electric circuit element to be received,
a high-frequency signal generator that generates a high-frequency signal and supplies it to the receiver; a detection means that detects the output level of the low-frequency signal after demodulation of the receiver; a display means that displays the output of the receiver; a receiver and a display means. a bandpass filter that is interposed between the receiver and selectively passes a low frequency signal included in the output after demodulation of the receiver, and has a variable attenuation amount in a frequency band other than the low frequency signal; In response to the detection output from the detection means, when the demodulated output level of the receiver is small, the attenuation amount of the bandpass filter is increased, and when the demodulated output level of the receiver is large, the attenuation amount of the bandpass filter is increased. An adjustment point detection device for a receiver, comprising: control means for controlling the amount of attenuation of the pass filter to be reduced.