JPS5843700B2 - spectrum display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spectrum display device, and by setting the sensitivity of the full-band level display to be relatively lower than the sensitivity of the spectrum display, the present invention relates to a spectrum display device. It is an object of the present invention to provide a spectrum display device which can simultaneously display a level display and a level display (spectral display) of a plurality of divided frequency bands, and which can easily perform sound field correction.

FIG. 1 shows a block diagram when a spectral display device is used for displaying the frequency spectral distribution of an input signal level-adjusted by a graphic equalizer.

In the figure, 1 is a spectrum display device, which includes a frequency band division filter that divides an input signal into a plurality of frequency bands, a display unit that displays the signal level from the frequency band division filter for each divided frequency band, and its driving circuit. It becomes more.

The spectrum display device 1 also has a full-band level display section that constantly displays the peak level of the input signal by directly displaying the level of the input signal without passing it through the frequency band division filter.

2 is a graphic equalizer which arbitrarily increases or attenuates the level of the input signal independently for each of a plurality of divided frequency bands.

The center frequency of each divided frequency band of the frequency band divided filter characteristic of the spectrum display device 1 is made to coincide with each center frequency of a plurality of divided frequency bands whose level can be adjusted by the graphic equalizer 2.

First, we will explain the operation when the changeover switches S1 and S2, which are switched by movement, are both connected to contact a.
For example, an audio signal input to the input terminal 3 is supplied to the graphic equalizer 2 via the changeover switch S□.

This graphic equalizer 2 has the characteristics as shown in Figure 2B, and can be set within the range of maximum amplification amount +■■ and maximum attenuation amount -■■ for each of n divided frequency bands from center frequency f□ to fn. , arbitrarily and independently adjust the level of the input audio signal and output it.

The output acoustic signal of the graphic equalizer 2 is outputted by the speaker 5 via the output terminal 4, and is also supplied via the changeover switch S2 to the spectrum display device 1, where the frequency spectrum distribution is displayed.

As mentioned above, the spectrum display device 1 has a frequency band division filter that divides into a plurality of frequency bands, and its characteristics are as shown by the solid line in FIG. 2A. The frequency characteristic of the full-band filter that outputs the signal is shown by the dashed line t in FIG. 2A.

Therefore, the spectrum display device 1 has changeover switches S and S.
2 is connected to the contact aσ, the graphic equalizer 2 increases or attenuates the level of the acoustic signal input to the input terminal 3, and displays the frequency spectrum distribution and the peak level of the signal, respectively.

Next, when the changeover switches S□ and S2 are connected to the contacts, the noise with constant energy per octave generated by the pink noise generator 9, that is, the pink noise, is transmitted through the changeover switch S□ to the graphic The signal is supplied to the equalizer 2, where all the n divided frequency bands normally pass through without being level-enhanced or attenuated, and are applied to the speaker 5 via the output terminal 4, thereby producing sound.

The sound waves emitted by the speaker 5 are transmitted to the microphone 6
The signal is then converted into an electrical signal and supplied to the spectrum display device 1 through the output terminal 7, the microphone amplifier 8, and the selector switch S2.

Here, the frequency spectrum distribution displayed on the spectrum display device 1 is that of the pink noise produced by the speaker 5, so it is not flat like the frequency spectrum of the original pink noise. Changes depending on the sound field.

Therefore, the sound field can be corrected by adjusting the level of a predetermined divided frequency band wave using the graphic equalizer 2 so that the frequency spectrum distribution displayed on the spectrum display device 1 becomes even.

Spectral display devices used for such purposes are spectral displays that divide an input signal into multiple divided frequency bands using a frequency band division filter, and display the level of each divided frequency band to display the frequency spectrum of the input signal. and an all-band level display section that passes the input signal through an all-band filter whose pass frequency band is all the frequency bands of the plurality of divided frequency bands and displays its peak level.

Here, the passband energy integral value of each band filter that selects the frequency of the signal of each divided frequency band among the plurality of divided frequency bands is P, and the passband energy integral value of the all-band filter is defined as P. Assuming P4, when the sensitivities of both filters are the same, each band filter for frequency band division has a pass output pink noise level of △ as shown by the following equation for the same input pink noise than the above-mentioned all-band filter. Only L has a lower level difference.

Note that the energy integral value P is the same in each divided frequency band regardless of the center frequency of the divided frequency band (provided that each band filter setting is different from each other).

) However, in conventional spectral display devices, the second
As shown in Figure A, since the sensitivities of both filters were the same, the energy integral value in the entire passband of the all-band filter is compared with the energy integral value in the passband G of each frequency band division bandpass filter. As a result, a level difference △L expressed by equation (1) arises, and if the latter level is set to a sensitivity that can be displayed within a limited display dynamic range, the former level becomes too large and exceeds the display dynamic range. In the end, the sensitivity of both filters had to be set to a level that would not cause the entire band level display to scale over, making it impossible to display both effectively within the limited dynamic range of the display. There were drawbacks.

The present invention eliminates the above-mentioned drawbacks, and embodiments thereof will be described below with reference to FIGS. 3 to 6.

FIG. 3 shows a block system diagram and a panel surface of a first embodiment of the spectrum display device according to the present invention.

In FIG. 4, reference numeral 10 denotes an input terminal, into which the output audio signal of the graphic equalizer 2 or the pink noise from the microphone 6 via the microphone amplifier 8 enters, as explained in conjunction with FIG.

This input signal is appropriately amplified by an amplifier 11 whose gain can be adjusted by a variable resistor VR, and then passed through bandpass filters 12□ to 1.
2n and attenuator 13, respectively.

The bandpass filters 12□ to 12n have passband widths whose center frequencies are f□ to fn, which are made to match the center frequencies f□ to fn of the divided frequency bands of the attached graphic equalizer, and whose respective frequency characteristics are as follows. In Figure 5, ■, ~I
As shown in
have.

In FIG. 5, the broken line ■ indicates the frequency characteristic of the conventional bandpass filter shown by the solid line in FIG.

Further, ■ indicates the frequency characteristic of the full band filter 15, which will be described later.

In this embodiment, the Q of the bandpass filters 12□ to 12n is selected to be about 8, which is about 4 times as large as that of the conventional filter, so that △f becomes △F.

This is because the spectrum display device of this embodiment and the graphic equalizer installed in the connection manner as shown in FIG. 1 enhance the maximum level of only one of the n divided frequency bands. In addition, all other divided frequency bands are determined in consideration of the fact that when the amount of level enhancement is zero, the spectrum display of pink noise in the level-enhanced divided frequency band and the adjacent divided frequency band will not be displayed as increasing. .

Moreover, the Q of the band filters 12□ to 12n was made into a dog because the Q of the frequency band division filter characteristic was small in conventional spectrum display devices, so the graphic
This is to eliminate the drawback that not only the level display of the divided frequency band whose level is adjusted by the equalizer but also the level display of the adjacent divided frequency band changes simultaneously with the level adjustment.

The respective output signals of the bandpass filters 12□ to 12n are converted into DC signals by rectifying and smoothing circuits 14□ to 14n, and then supplied to the level axis drive circuit 18.

On the other hand, the input signal attenuated and taken out by the attenuator 13 is sent to the rectifying and smoothing circuit 16 via the full-band filter 15 having a pass frequency bandwidth including all the n divided frequency bands formed by the band-pass filters 12□ to 12n. Here, the signal is converted into a DC signal according to the peak level of the input signal, and then supplied to the level axis drive circuit 18.

Here, the frequency characteristic at the output end of the full-band filter 15 is as shown by the solid line ■ in FIG. 5, and is relatively The sensitivity is set low so that the level becomes lower by ΔL'.

This level difference ΔL' is selected to a value such that the indicated value of the entire band level display for the pink noise input signal is approximately the same as the indicated value of the spectrum display in the divided frequency bands of each center frequency f1 to fn. Ru.

For example, the Q of each of the bandpass filters 12□ to 12o is 8,
When n is 10, ΔL expressed by the above equation (1) under the condition that the sensitivity of the entire band level display and the spectrum display are the same is approximately 17.2 dB (note that P 1 =, n P
), so in order to set this △L to O, we write △L' in Figure 5.
As shown, the input level of the full-band filter 15 is set to be relatively low by about 17.2 dB with respect to the input level of the band-pass filters 12□ to 12n.

The level axis drive circuit 18 and the frequency axis drive circuit 19 are both synchronized by time division pulses from the decoder 17, and their output signals are supplied to the display section 20.

As a result, the rectifying and smoothing circuit 14□. 14 14...
, 14n output signals f□, f2°f3
．． . . . on the frequency axis of f. A plurality of rectangular light emitting elements (full band level display section 22
The peak level of the input signal is displayed as a bar graph.

The spectrum display section 2F displays the frequency spectrum distribution of the input signal.

According to this embodiment, since the sensitivity of the entire band level display is set relatively lower than the sensitivity of the spectrum display by ΔL', each center of f0 to fn is set within the limited display dynamic range. It is possible to effectively display the level for each of the n divided frequency bands having frequencies. In particular, when the Q of each of the band filters 12□ to 12 is set to a dog, the level of each of the band filters 12□ to 12n can be displayed effectively. The energy integral value in the entire passband of the filter is extremely small compared to that of the full-band filter, and if the sensitivity of the spectrum display is adjusted to the dynamic range that can be displayed, the full-band level display will overscale. In addition, since the sensitivity of the above-mentioned full-band level display is set relatively lower than the sensitivity of the spectrum display by △L', the full-band level display can be prevented for the same pink noise human power. The indicated value of the section 22 and the indicated value of the spectrum display section 21 can be made almost the same, and therefore, when correcting the sound field characteristics evenly using the graph ink equalizer and pink noise, the entire band level display section This can be easily done by setting the indicated value of 22 as a reference level and adjusting the graphic equalizer so that the indicated value of the spectrum display section 21 is aligned with this value.

FIG. 4 shows a block system diagram and a panel surface of a second embodiment of the spectrum display device according to the present invention.

In the figure, the same parts as in FIG. 3 are given the same reference numerals, and their explanations will be omitted.

This embodiment is characterized in that the Q of the frequency band dividing bandpass filter is changed depending on the application, and at the same time, the sensitivity of the overall band level display is also changed.

In FIG. 4, the center frequencies of the passing frequency bands of 23□ to 23n are f□ to f, which are made to match the center frequencies f0 to fn of the divided frequency bands of the attached graphic equalizer, and each of them The frequency characteristics are shown in Figure 2A.
It has the same characteristics as the conventional characteristics shown by the solid line.

Furthermore, the center frequencies of the pass frequency bands of the bandpass filters 24□ to 24n connected in cascade to the bandpass filters 23□ to 23n are also f□ to fn, and the frequency characteristics of the output signals are shown in Fig. 5. It is configured as shown by I.

FIG. 6 shows the i-th band filter 231 of the band filters 23□ to 23n and the band filters 24□ to 23n.
This is a specific circuit diagram of an embodiment of a bandpass filter in which the i-th bandpass filter 241 of 24n is connected in cascade, and is a multiple feedback active bandpass filter using operational amplifiers 26 and 27. ing.

The output signals of the bandpass filters 23□ to 23n are supplied to the contacts C of the changeover switches SW□ to SWo, which are switched by movement, and the output signals of the bandpass filters 24□ to 24n are supplied to the contacts d of the changeover switches SW0 to SWn. Ru.

Therefore, depending on the changeover switches SW□ to SWn, the filter output signals with low Q from the bandpass filters 23□ to 23n or the filter output signals from the bandpass filters 24□ to 24. A filter output signal with a higher Q is selectively taken out and sent to the rectifier and smoothing circuit 14.
□ to 14n, respectively.

On the other hand, the attenuator 25 converts the input signal from the amplifier 11 into signals of different levels through the switch SWn+.
□ is supplied to contacts c and d, respectively.

This changeover switch SWn+□ is changeover switch SW□~S
When pink noise enters the input terminal 10, the output signal level of the attenuator 25 is relatively lower than the output signal level of the bandpass filters 23□ to 23n when the contact 76c is connected. On the other hand, when the contact d is connected, the attenuator 25 removes all the pink noise whose level is relatively △L' lower than the output signals of the bandpass filters 24□ to 24n. The signal is supplied to the bandpass filter 15.

Frequency band division bandpass filters 23□ to 23n.

The sensitivity of the entire band level display is changed in response to the switching of Q of 24□ to 24n, and when the contacts d of the changeover switches SW□ to SWn are connected, the same operation as in the first embodiment is performed.

The spectrum display device of this embodiment is used as the spectrum display device 1 in FIG. 1, and the changeover switch SWI SWn+
□ is linked with the changeover switches S□, S2, and when the contact a of the changeover switches S□, S2 is closed, the changeover switch SW□
By configuring ~SWn+□ to be connected in a closed manner to the contact C, the sound field characteristics due to pink noise can be corrected by aligning the indicated values of the spectrum display section 21 with the indicated values of the entire band level display section 22 as a reference. Sound field characteristics can be easily flattened, and accurate spectrum display can be performed.

In addition, since the sensitivity of the whole band level display is set relatively lower than the sensitivity of the spectrum display, the level display for each divided frequency band with each center frequency f□ to fn and the whole band level display are limited. The displayed dynamic range is effectively utilized.

It goes without saying that the attenuators 13 and 25 are not limited to those that attenuate the input signal by a certain amount, but may be of a structure that allows the level attenuation amount to be arbitrarily varied continuously.

As described above, the spectrum display device according to the present invention is provided with means for attenuating the input signal level of the full-band filter relative to the input signal level of each of the plurality of band-pass filters for frequency band division. Since the sensitivity of the band level display is set relatively lower than that of the spectrum display, the limited display dynamic range of the spectrum display section and the full band level display section can be effectively used for both the spectrum display and the full band level display. It is possible to display the peak level of the band, and it is also possible to vary the amount of attenuation by the attenuation means according to the content of the input signal. , while sufficiently narrowing the pass frequency band width of each of the band filters for frequency band division, and when the input signal to be displayed is pink noise, the level indication value of the spectrum display section and the level of the entire band level display section. The input signal level of the full-band filter for displaying the full-band level is set relative to the input signal level of each of the plurality of band-pass filters for frequency band division by a predetermined amount that is approximately the same as the indicated value. Since a means to attenuate the noise is provided, pink noise that has passed through a graphic equalizer is emitted from a speaker, which is converted into an electrical signal by a microphone, and this electrical signal is used as an input signal for a spectrum display device to correct the sound field characteristics. When doing so, it is extremely easy to make corrections that even out the sound field characteristics by adjusting the graphic equalizer so that each indication value on the spectrum display section is uniform based on the level indication value on the entire band level display section. Also, even if the level of only a certain divided frequency band is adjusted using a graphic equalizer when inputting pink noise, the level indication values of adjacent divided frequency bands will not change simultaneously with this level adjustment, and therefore the level will be even higher. It has many features such as being able to accurately correct sound field characteristics.

[Brief explanation of the drawing]

Figure 1 is a block system diagram showing an example of the case where a spectrum display device is used to display the frequency spectrum distribution of an input signal whose level has been adjusted by a graphic equalizer. 3 and 4 are block diagrams and diagrams showing the panel surfaces of each embodiment of the spectrum display device according to the present invention, and FIG. 5 is a diagram showing the frequency characteristics of the spectrum display device and graphic equalizer. FIG. 6 is a diagram showing an example of the frequency characteristics of the main part of FIG. 3 or FIG. 4, and FIG. 6 is a specific circuit diagram showing an example of the main part of FIG. 1... Spectrum display device, 2... Graphic equalizer, 6... Microphone, 9... Pink noise generator, 10...
・・Input terminal, 12□~12n, 231~23n, 24
□~24n...Band filter for frequency band division, 13, 25...Attenuator for sensitivity adjustment, 1
5...Full band filter, 21...Spectrum display section, 22...Full band level display section,
S□, S2...Input selection switch, sw
-8vv...Switch for filter Q switching 1 n CH, SW...Switch for sensitivity selection. n+1

Claims (1)

[Scope of Claims] 1. A spectrum display unit that divides a human signal into a plurality of frequency bands using a plurality of bandpass filters for frequency band division and displays the level of each frequency component signal of each divided frequency band; A spectrum display device having a full-band level display unit that displays the peak level of the input signal through a full-band filter that uses all of the plurality of divided frequency bands as one pass frequency band, Means is provided to attenuate the input signal level of the full band filter relative to the input signal level of each of the band filters, and the sensitivity of the full band level display is set relatively lower than the sensitivity of the spectrum display. A spectrum display device characterized by: 2. A spectrum display unit that divides the human signal into a plurality of frequency bands using a plurality of bandpass filters for frequency band division and displays the frequency component signals of each of the divided frequency bands at respective levels; In a spectrum display device having an all-band level display section that displays the peak level of a signal passed through an all-band filter that uses all divided frequency bands as one passing frequency band, adjacent divided frequency bands of the plurality of divided frequency bands are The pass frequency bandwidth of each of the frequency band division band filters is made sufficiently narrow compared to the frequency interval between both center frequencies of the frequency band, and when the input signal is pink noise, the spectrum display section and the level indication value of the all-band level display section are approximately the same. A spectrum display device comprising means for relatively attenuating the input signal level of a filter.