JP2592046Y2 - Spectrum analyzer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrum analyzer, and more particularly to a spectrum analyzer for suppressing display flicker caused by a minute level fluctuation. 2. Description of the Related Art For example, many spectrum analyzers usually provided in audio devices display frequency characteristics of reproduced sound from the viewpoint of convenience for users. In such an audio spectrum analyzer, in order to perform a discrete display by an indicator display, level data for each desired band is obtained from an input signal to be spectrum-analyzed, and the obtained level data is used as a reference for each discrete display level. The level is compared, and the indicator of the corresponding reference level is lit and displayed according to the comparison result. As described above, in a conventional audio spectrum analyzer, when converting band signal level data into display data, one reference level is used for each band. Only set. Therefore, when the signal level data for each band fluctuates in the vicinity of a certain reference level, a lamp one point (one step) above the reference level frequently turns on and off, so that the display is very difficult to see. There is a problem that it becomes. Accordingly, an object of the present invention is to provide a spectrum analyzer that minimizes a change in the lighting state of an adjacent display lamp due to a minute change in band signal level data. [0005] In order to solve the above-mentioned problems, a spectrum analyzer according to the present invention divides a display level into a plurality of level ranges for a predetermined band, and displays an indicator corresponding to each level range. A spectrum analyzer for detecting the signal level of each of the predetermined bands of the input signal, comparing the detected signal level with a reference level defined for each of the divided ranges, and lighting and displaying an indicator according to the comparison result. A determination means for detecting a change in the detection signal level to determine an ascending or descending change in the level change; and a reference level storage means for storing a reference level defined corresponding to the ascending or descending level change. And a reference level corresponding to an ascending or descending change in the level change determined by the determining means. Control means for comparing the output signal level and lighting the corresponding indicator. According to the present invention, a rising change and a falling change of an input signal level are determined, and a reference level determined at the time of rising and falling of the level change is compared with a detected input signal level. Turn on the indicator corresponding to. The indicator divides the display level into a plurality of level ranges for a predetermined band, is provided corresponding to each level range, and determines a signal level detected for each predetermined band for the input signal for each division range. Compare to the reference level,
An indicator according to the comparison result is turned on. Next, this invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment of a spectrum analyzer according to the present invention, and shows an application example to an audio apparatus. In this embodiment, a signal level detector 1 for each band is used.
, A microcomputer 2 and a display unit 3. The input audio signal is provided in the signal level detection unit 1 for each band, for example, for obtaining a signal for each of three predetermined frequency bands of a high frequency band, a middle frequency band, and a low frequency band. The signals are input to the high-pass filter 11A, the middle-pass filter 11B, and the low-pass filter 11C, and three band (high-, middle-, and low-band) signals are obtained. The band signals obtained by each of the band-pass filters 11A, 11B and 11C are input to corresponding DC detection circuits 12A, 12B and 12C, and a DC signal proportional to the magnitude of the input signal is detected. The signals are supplied to corresponding A / D converters 13A, 13B and 13C, and band digital level data for each band is output. The microcomputer 2 has a ROM 2
1, a CPU 22, and a RAM 23 are built in. The ROM 21 stores a program that defines the processing procedure of the CPU 22, and a reference level data group for each band. ROM 21
For example, reference level groups UB0 to UB5 when the level increases and reference level groups DB0 to DB5 when the level decreases as shown in FIG. 2 are stored. The CPU 22 uses the RO
According to the program procedure stored in M21, the digital data from the band-specific signal level detector 1 is compared with the reference level data and processed. In addition, the RAM 23 has
, The band-specific signal level data AD (i) output from the band-specific signal level detection unit 1 (i = 1, 2, 3)
And the band-specific signal level data PD (i) (i = 1) taken one time before the current AD (i) area.
1, 2, 3), an area used as a counter i on the program, and an area storing a display level LD (i) (i = 1, 2, 3) displayed on the display unit 3. Is provided. Here, i = 1 indicates a low frequency band, and i =
2 indicates a middle band, and i = 3 indicates a high band. The display unit 3
The low-band signal level, the mid-band signal level, and the high-band signal level are displayed by controlling the lighting of a plurality of lamps (eg, LEDs) arranged in the vertical direction. Now, the CPU in the microcomputer 2
The processing procedure of Step 22 will be described below with reference to FIG. FIG. 4 shows a flowchart of the processing procedure of the CPU 13 specified in the program stored in the ROM 21. First, the CPU 21 initializes the area PD
(I) “0” is set in (i = 1 to 3) and the area LD (i)
“0” is stored in each (i = 1 to 3) (step S1). Next, the signal level data for each band is fetched from the signal level detecting section 1 for each band,
In (1), the middle band data is stored in the area AP (2), and the high band data is stored in the AP (3) (step S2). For the next repetition processing, 1 is stored in i as an initial setting of the counter (step S3), and the data AD (i) read from the area AD (i) and PD (i) of the number i designated by the counter are set. i) is compared with PD (i) (step S4), and if AD (i) <PD (i), the reference level data group at the time of level decrease is compared with AD (i) in step S5 to change the display level. Find and LD
(I). On the other hand, in step S4, AD
If (i) ≧ PD (i), in step S6, the display level is obtained by comparing the reference level data group at the time of level increase with AD (i), and the result is stored in the corresponding area as LD (i). After steps S6 and S7, the data AD
(I) is stored as PD (i) of the corresponding area, the parameter i is incremented (step S7), and i <4 is determined in step S8 (step S8). If the determination in step S8 is i ≧ 4, the data LD
(1) -Low range, middle range,
After displaying the signal levels of the three bands of the high band and the high band, the process returns to the step S2. Now, for example, the reference level data group at the time of level increase is UBO = 10, UB1 = 20, UBB2 = 3.
0, UB4 = 50, UB5 = 60, and the reference level data group at the time of level decrease is DBO = 6, DB1 = 16, DB
2 = 26, DB3 = 36, DB4 = 46, DB5 = 56
And It is also assumed that PD1 = 0, AD1 = 20, and i = 1. In step S4, data PD (i) which is the previous signal level data and AD (i) which is the latest data
Are compared, it is determined that the signal level is rising when the data AD (i) is larger than the data PD (i), and the signal level is falling when the data AD (i) is smaller. Judge that you are. A reference level data group is selected based on such a determination process. At this time, since PD (i) <AD (i), in step S6, the display level is obtained by comparing the reference level data group at the time of level increase with the data AD (i). The display level is set to 0 (no display) when 0 <AD (1) <UB0, 1 when UB0 ≦ AD (1) <UB1, and 2 when UB1 ≦ AD (1) <UB2. . In this case, AD (1) is UB2 ≦ AD
(1) Since there is a relationship of <UB3, the display level is 2, and 2 is stored in LD (1) and 2 is stored in i in step S7. In step S9, since LD (1) is 2, the lower two indicators are turned on and the upper three indicators are turned off on the low-frequency display unit 31 of the display unit 3 in FIG. I = 2, i for AD (2) and AD (3)
= 3, the same processing is performed. Next, returning to the processing of step S2, when 19 is entered in AD (1), step S4
Is determined to be a level drop, and the display level is obtained using the reference level data group at the time of the level drop. As described above, in the present invention, since the reference level data group at the time of lowering the level is used, the display level becomes 2, and the display does not seem to change. Therefore, even if the signal level data to be ignored fluctuates in the vicinity of the reference level data, the apparent display does not change and it becomes very easy to see. On the other hand, since the conventional spectrum analyzer sets only one reference level data group, for example, if the reference level data group is the same as UB, the display level becomes 1. In other words, when the operation of the band-specific signal level detection unit is unstable and the signal level data AD1 fluctuates between 19 and 20, the display levels are repeatedly displayed as 1 and 2 accordingly, making the display very difficult to see. Become. The display of the spectrum of the audio reproduction signal is for recognizing the maximum value of the time series of the reproduction signal for each frequency. Therefore, in order to make the maximum value better recognized, the hysteresis is displayed with a relatively large width in a peak hold manner. In particular, music signals often contain high-level outputs momentarily, and if the hysteresis is set narrow, such instantaneous reproduced signals cannot be displayed (they appear to be lit darkly). ). Also,
Although it is not a car audio, it is effective to hold and display an instantaneous peak level for a relatively long time when determining a recording level or an output level by connecting to a recording device. In the present invention, a reference level for determining the hysteresis characteristic is defined for each of the rising and falling levels. For example, when the peak falls within the hysteresis width when falling from the peak (maximum value), once The next higher level can be illuminated to recognize the presence of a peak, and if it rises from the bottom (minimum value), if the bottom is within the hysteresis width, it will be once lower level Is turned on so that the bottom can be recognized. As described above, in the spectrum analyzer according to the present invention, the reference level group for determining the display level is set in correspondence with the rising and falling of the level. Since a hysteresis effect is imparted by using differently, display flicker caused by a small level change before and after the reference level can be suppressed, and an easy-to-view display can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration block diagram showing an embodiment of a spectrum analyzer according to the present invention. FIG. 2 is a diagram showing an example of contents stored in a ROM of a microcomputer 2 in the embodiment shown in FIG. FIG. 3 is a diagram showing an example of contents stored in a RAM of the microcomputer 2 in the embodiment shown in FIG. FIG. 4 is a flowchart showing a processing procedure of a CPU stored in a ROM of the microcomputer 2 in the embodiment shown in FIG. [Description of Signs] 1 band-specific signal level detection unit 2 microcomputer 3 display units 11A to 11C band pass filters 12A to 12C DC detection circuits 13A to 13C A / D converter 21 ROM 22 CPU 23 RAM

Claims (1)

(57) [Claims for utility model registration] The display level is divided into a plurality of level ranges for a predetermined band, and an indicator corresponding to each level range is provided.
A spectrum analyzer that detects a signal level of each predetermined band for an input signal, compares the detected signal level with a reference level determined for each division range, and lights and displays an indicator according to the comparison result. Detecting means for detecting a change in the detection signal level, determining a rising change of the level change, and determining a falling change; reference level storing means for storing a reference level determined corresponding to the rising and falling of the level change; Control means for comparing a reference level corresponding to an ascending or descending change in the level change determined by the determining means with the detection signal level, and lighting the corresponding indicator. analyzer.