JPS59158119A - Level display device - Google Patents

Abstract

PURPOSE:To confirm the mutual relation between an input and a muting level clearly and easily and to facilitate the setting of the muting level by switching and displaying the input level and muting level on one display means. CONSTITUTION:The output of a 1F circuit 3 is converted by a rectifying circuit 10 and supplied to a comparing circuit 12 to obtain an output corresponding to an input signal. The comparing circuit 12 is supplied with a reference value corresponding to the set value of the muting level. Therefore, the comparing circuit 12 generates an output according to whether the signal level from the rectifying circuit 10 is larger than the reference value or not. The reference value is set by a variable resistor 13. A switch 17 for switching the display means is provided, and when the muting level is set, the switch is placed at the side of a contact (b) and the resistor 13 is varied by looking at a meter to set the muting level to a desired level. The switch is placed normally at the side of a contact (a) to display the signal level on the meter. When the muting level is checked during reception, the switch is switched to the side (b) to display the current set level on the meter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a level display device suitable for use, for example, in displaying a signal level or muting level in an FM receiver.

Background Art and Problems In general, in FM receivers, if the carrier wave is large, the S/N ratio is improved due to the limiter effect, but when the peak of the carrier wave and the peak of the noise voltage are the same, below the so-called threshold level, When the limiter effect disappears, the amplitude modulation and the phase modulation also increase, resulting in a sudden increase in noise. Therefore, if such noise is likely to occur, for example, if you are receiving a broadcast while selecting a channel, or if you are receiving a broadcast with an extremely weak signal input, you may want to adjust the output of the receiver to eliminate such noise. A so-called muting circuit for blocking is provided in the receiver.

Further, some FM receivers of the normal synthesizer tuner type have an auto-tuning function, and in such receivers, it is common practice to use the auto-tuning stop signal also as a muting signal.

By the way, in areas where radio waves with various signal strengths are mixed, it is necessary to use FM with a fixed muting level.
The receiver may not be able to release muting or stop auto-tuning when a signal is higher than the set muting level, and may respond to signals that are not originally required by the user. In order to eliminate these inconveniences, an FM receiver has been proposed in which the user can normally set the muting level as desired.

In such FM receivers, the muting level is generally set using a variable resistor, or the muting level setting value is displayed on the knob or groove surface to which the variable resistor is attached. This is done by printing a scale. Tsu′=! , the input signal strength level display and the muting level setting value display are treated as completely different things. Therefore, in such a method, if variations occur in the variable resistor's changing characteristics or mechanical parts, the scale can only serve as a guide, and good accuracy cannot be obtained. 1. In actual use, although there is a deep relationship between the input signal strength level and muting level setting values, the relationship between them is not clear.

Purpose of the Invention In view of the above, the present invention provides a highly accurate method that allows the mutual relationship between the input signal level and the muting level to be clearly and easily confirmed, and also allows the muting level to be easily set to any desired value. A level display device is provided.

SUMMARY OF THE INVENTION The present invention includes a signal detection means for obtaining an output according to the input signal strength, a level setting means for setting a muting level, and a comparison between the output of the signal detection means and the output of the level setting means. a comparison means for obtaining a testing output;
A level display device comprising a display means, wherein the display means is switched to display the output of the signal detection means and the output of the level setting means,
The mutual relationship between the input signal level and the muting level can be clearly and easily confirmed, and the muting level can be easily set.

EXAMPLE The present invention will be described in detail below with reference to FIGS. 1 and 2, taking as an example the case of receiving F'M stereo broadcasting.

Figure 1 shows the circuit configuration of this embodiment. In the figure, broadcast waves captured by a receiving antenna (1) are transmitted to a high frequency circuit (2) including a frequency conversion circuit and a local oscillation circuit (not shown). ) is converted into an intermediate frequency signal, then supplied to an intermediate frequency amplifier circuit (3) for amplification, and further supplied to an FM detector (4) including a limiter for demodulation. This demodulated signal is sent to the FM multi-solex circuit (5).
where the left channel 1 word of the stereo signal (
L) and right channel believe! (R) is separated and taken out and output to output terminals (8) and (9) via gate circuits (6) and (7), respectively.

In addition, a rectifier circuit 00) consisting of a capacitor, a diode, etc. is provided on the output side of the intermediate frequency amplifier circuit (3) in order to obtain an output according to the input signal strength, and the output of the intermediate frequency amplifier circuit (3) is After the signal is converted into a DC signal by the rectifier circuit 00), it is sent to the comparator circuit (12) via the buffer circuit 0υ.
is supplied to one input terminal of This comparison circuit (12)
A reference value corresponding to the muting level setting value described later is given to the other input terminal of the
Therefore, when the level of the signal supplied from the comparator circuit (14 is the rectifier circuit α0 via the buffer circuit 0υ) is smaller than the reference value, a muting output is generated on the output side. Dirt circuit (6)
and (close the force f-t, FM multigrex circuit (
5) so that the left channel signal and right channel signal are not output to the output terminals (8) and (9), respectively.

On the other hand, when the signal level from the rectifier circuit GQI is higher than the reference value, the comparator circuit 02) uses its output signal to open the date circuit (6) and the power dart, and the FM multi-lux circuit (5) The left channel signal and the right channel signal are outputted to output terminals (8) and (9), respectively.

A variable resistor (13) is provided as a reference value setting means,
One end of this variable resistor 03 is connected to the positive voltage source terminal 1B via a resistor α, and the other end is grounded via a resistor (15). The sliding terminal of this variable resistor (13) is connected to the other input terminal of the comparator circuit a via the buffer circuit αe. Therefore, by setting the muting level using the variable resistor (13), a reference value corresponding to the desired muting level is applied to one input terminal of the comparator circuit (12).

Further, a switch aη for switching display means is provided on the output side of the buffer circuits (1υ and (16)), and this switch a
The contact a of 7) is connected to the output side of the buffer circuit <11), and the contact a is connected to the output side of the buffer circuit (16). A common terminal of the switch circuit αD is grounded via a semi-fixed resistor αυ. And this resistor a
The sliding terminal 8 is connected to a meter (a) as a display means via a buffer circuit a. And when setting the above muting level, use the switch (17)
switch to the contact side, and connect the meter as shown in Figure 2A (
Adjust the variable resistor 03) while looking at the scale 20) to set it to the desired muting level, for example 30 dB. Therefore, if the input signal strength is below this muting level of 30 dB, the output of the receiver will be cut off.

In the normal reception state, the switch (Iη) is switched to the contact a side.Then, the meter ■ is switched to display the signal level as shown in Figure 2B, and the rectifier circuit 0
0) etc., the level is displayed according to the strength of the signal supplied thereto.

Also, if you want to check what value the muting level is set to when receiving broadcasts, etc., by switching the switch αη to the contact side each time, the currently set muting level will be displayed on the meter ( 2υ.Therefore, the user only needs one meter (20)
By simply switching the switch 0η, the relationship between the human input signal level and the muting level can be immediately confirmed.

Note that the swing width of the meter +20 is adjusted using a semi-fixed resistor θ mark. Furthermore, even if there is a deviation between the scale of the meter (20) and the absolute value, the relationship between the signal strength and the muting level setting value remains unchanged, so the muting level should be set under actual usage conditions. There is no problem.

In this manner, in this embodiment, the mutual relationship between the signal strength level and the muting level can be easily confirmed by using one meter.

APPLICATION EXAMPLE In the above-described embodiment, the present invention has been explained using the case of receiving FM stereo broadcasting as an example, but the present invention is not limited to this, and the present invention can also be used to display the signal level and muting level of other transmission information. It is similarly applicable to other cases.

Effects of the Invention As described above, according to the present invention, since the level corresponding to the input signal strength and the muting level are displayed by switching one display means, it is easy to see the mutual relationship between the signal input level and the muting level. The muting level can be clearly and easily checked, and the muting level can be easily set.

[Brief explanation of the drawing]

Figure g1 is a circuit configuration diagram showing an embodiment of the present invention, and Figure 2 is a diagram for explaining the operation of Figure 1. (5) U F M -r Roux y-grex circuit,
+6), (7) is r-) circuit, 00) is rectifier circuit,
(+1), +16), living 9, sofa circuit, G
2) is a comparison circuit, Φ is a variable resistor, aη is a switch, r
21 is a meter. Figure 1

Claims (1)

[Claims] A signal detecting means for obtaining an output according to the input signal strength, a level setting means for setting a muting level, and a comparing means for comparing the output of the signal detecting means and the output of the level setting means to obtain a muting output. , and display means, wherein the display means is switched to display the output of the signal detection means and the output of the level setting means.