JPH04295772A - Level measuring device - Google Patents

Abstract

PURPOSE:To obtain a level measuring device of a small size able to make the preservation and analysis of measured data. CONSTITUTION:Among the outputs put out after input signals are mixed with local oscillation signals to convert frequency by a frequency conversion measure 22, a signal within a passband to center about around a fixed frequency is passed by a passband variable filter measure 24, and the output level of this signal is detected by a level detecting measure 26, stored by a store measure 36 and displayed by a display 28. A local oscillation signal is changed into the frequency to change a measured signal into the fixed frequency by a change measure 30, according to the input of the frequency and kind of the measured signal, and the passband variable filter measure 24 is changed to the band according to the kind of the measured signal. A plurality of groups of the frequency kind and allowable level range of the measured signal is stored by an input information store measure 32, and the next group is automatically supplied to the change measure 30, at every measurement end of one measured signal. The output of the level detecting measure 26 and the allowable level range to this are judged by a judging measure 34.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a level measuring device for measuring the level of each frequency component of a signal under test.

0002

2. Description of the Related Art Generally, a new communal viewing facility as shown in FIG. 5, for example, is sometimes installed. In such a communal viewing facility, the head 2 transmits TV, FM broadcast signals, satellite broadcast signals, satellite communication signals, independent broadcast signals, and security downstream signals. In addition, TV and FM broadcast signals are
The satellite broadcast signal is received by TV and FM receiving antenna 4.
The satellite communication signal is received by the satellite communication receiving antenna and converter 6, the satellite communication signal is received by the satellite communication receiving antenna and converter 8, and the independent broadcast signal is obtained from the VTR 10 and the TV camera 12. The security downlink signal is obtained from the security center device 14. And each of these signals is
It is transmitted from the head end 16, amplified by various amplifiers 18 interposed in the main line and branch lines, and then sent to the branch 20 at each terminal.
It is supplied to each household through In addition, security uplink signals from each home are sent to the head 2 via the above-mentioned amplifiers 18.
The information is supplied to the security center device 14 of.

When such a communal listening facility is newly installed, it is important to check whether the levels of various signals at the input side, output side, and branch (or distribution) side of each amplifier 18 are at the expected levels. It is necessary to determine whether Conventionally, such a determination has been made by measuring each of the above levels using a checker or spectrum analyzer, and having the worker calculate the deviation between this level and a standard level to determine whether or not it is normal.

0004

[Problems to be Solved by the Invention] However, when a checker is used, there is a problem that measurement data cannot be stored or analyzed. In addition, when using a spectrum analyzer, it is possible to save and analyze measurement data when combined with a computer, but the device becomes large and cannot be used to measure the levels of amplifiers 18 installed at various locations. However, there is a problem that it is inconvenient to carry.

[0005] An object of the present invention is to provide a level measuring device that eliminates the inconvenience caused when using the above-mentioned checker or spectrum analyzer.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention mixes an input signal with a local oscillation signal of a specified frequency and converts the frequency, as shown in FIG. Frequency conversion means 22 and this frequency conversion means 22
A variable pass band filter means 24 for passing a signal in a designated pass band approximately centered at a predetermined frequency among the outputs of the filter means 24, a level detecting means 26 for detecting the level of the output of this filter means 24, and a level detecting means 26 for detecting the level of the output of this filter means 24; Detection means 2
and a display means 28 for displaying the output of 6. Furthermore, the present invention also includes changing means 30 for changing the frequency of the local oscillation signal of the frequency converting means 22 and the pass band of the variable pass band filter means 24. The frequency of the signal under test and its type are input to the changing means 30, and the changing means 30 controls the local oscillation of the frequency converting means 22 so that the signal under test is frequency-converted into a signal of the predetermined frequency. Change the frequency of the signal. Furthermore, the changing means 30
changes the passband of the variable passband filter means 24 according to the type of input signal under test. The present invention further includes an input information storage means 32, in which a plurality of sets of frequencies and types of measurement signals to be input to the changing means 30 are set.

Further, in the present invention, the input information storage means 32
The input of the frequency and type of the signal under test to the changing means 30 can be performed automatically each time the level measurement of one signal under test is completed, or the input of the frequency and type of the signal under test to the changing means 30 can be done automatically each time the measurement of the level of one signal under test is completed. It can also be configured to be performed in response to an operation.

Further, in the present invention, the input information storage means 32
In addition to the frequency of the signal under test and the type of signal under test, a permissible level range corresponding to the signal under test is set, and the permissible level range corresponding to the frequency of the signal under test input to the changing means 30 is set. It is also possible to provide a determining means 34 which receives a level range and determines this and the output of the level detecting means 26. Furthermore, a storage means 36 for storing the output of the level detection means 26 may be provided.

[0009]

[Operation] According to the present invention, when the frequency and type of the signal under test are input from the input information storage means 32 to the changing means 30, the changing means 30 changes the frequency of the local oscillation signal according to the input frequency. change. As a result, the signal under test among the input signals is converted into a signal of a predetermined frequency in the frequency converter 22. This converted signal is
The signal is supplied to the variable passband filter means 24. At this time, the changing means 30 sets the passband of the variable filter means 24 in accordance with the type of signal under measurement. The output of the filter means 24 is detected by the level detection means 26 and displayed on the display means 28. Therefore, if the frequency and type of the measured signal supplied from the input information storage means 32 to the changing means 30 are sequentially changed automatically or manually, each of the measured signals set in the input information storage means 32 The frequency level of the signal can be measured.

[0010] Further, by providing the determining means 34, it is possible to automatically determine whether each level measured as described above is within the permissible level range. Furthermore, if a storage means 36 is provided, each level measured as described above can be memorized and saved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below based on an embodiment shown in FIGS. 2 to 4. The level measuring device of this embodiment is for measuring the levels of the input, output, and branch (distribution) terminals of each amplifier in a public listening facility, and has an input terminal 40 as shown in FIG. There is. This input terminal 40 is connected, for example, to the input, output, or branch (or distribution) terminal of each of the above-mentioned amplifiers. Input of the above amplifier,
As mentioned above, the output or branch (or distribution) terminal can receive TV, FM broadcast signals, satellite broadcast signals, satellite communication signals,
A plurality of signals of different frequencies are generated, such as a self-broadcasting signal, a security downlink signal, and a security uplink signal. These signals are frequency-converted by frequency conversion means 42. This frequency conversion means 42 has a mixing section 44 and a local oscillation section 46, and converts the center frequency of the signal under test whose level is to be measured among the various signals mentioned above to a predetermined frequency, for example, 10.7 MHz. The frequency of the local oscillation signal of the local oscillation unit 46 is set so that . Further, the output signal of the mixing section 44 is transmitted to the passband variable filter means 4.
8. This variable filter means 48 has a center frequency of 10.7 MHz, but has different pass bands, for example, 250 KHz and 600 KHz.
, 10MHz bandpass filters 50, 52,
54, and among these, the type of signal to be measured, for example, T
Switch 5 is selected depending on whether it is a V broadcasting signal, a satellite broadcasting signal, a satellite communication signal, etc.
1 and 53, the output of the mixer 44 is supplied. Therefore, as the output of this variable passband filter means 48, the center frequency of the signal under test is set to 10.
The signal converted to 7 MHz is output only in a band selected according to the type of signal under test. This signal is amplified by amplifiers 56, 58 and then supplied to level detection means, such as a rectification/smoothing circuit 60, where its level is detected. This detected level is converted into a digital level signal by the A/D converter 62 and supplied to the CPU 66 via the bus line 64.

By the way, as mentioned above, various signals are supplied to the input terminal 40, and their levels also vary considerably. Therefore, in some cases, the A/D converter 6
When A/D conversion is performed using 2, overflow may occur. Therefore, the variable attenuator 6 is connected to the input terminal 40.
8 is provided. This means that when the signal under test is not excessive, the signal is passed through the switches 70 and 72, and when the signal under test is excessive, the signal is passed through the switches 70 and 72.
2, the signal at the input terminal 40 is supplied to the attenuator 74, attenuated by a predetermined amount, and then output. Note that switching control of the switches 70 and 72 is performed by the CPU 66. Also, C is equal to the amount attenuated by this attenuator 74.
Correction is performed on the digital level signal from the A/D converter 62 in the PU 66 .

Further, as described above, there are various signals supplied to the input terminal 40, and the frequency range of these signals is wide, for example, from 10 MHz to 770 MHz. If all the signals in such a wide frequency range were to be converted to 10.7 MHz using only the frequency conversion means 42, the frequency range over which the local oscillator 46 would have to oscillate would become too wide. Therefore, the frequency range in which the local oscillator 46 oscillates is narrowed, for example from 289.3 MHz to 75 MHz.
To limit the frequency to 9.05MHz, the signal under test must be 300MHz.
MHz to 770MHz, switch 76
, 78, and send this signal under test as it is to 300.
The signal is passed through a band pass filter 80 having a pass band from MHz to 770 MHz, and is supplied to the frequency conversion means 42. Also, the signal to be measured is from 10MHz to 300M.
Hz, the switches 76 and 78 are switched to supply this measured signal to the frequency converting means 82.
After converting the frequency from 410 MHz to a signal of 700 MHz, the signal is supplied to the frequency converting means 42. The frequency conversion means 82 has a pass band of 10 MHz to 300 MHz.
a bandpass filter 84, a mixing section 86, a local oscillation section 88 whose local oscillation frequency is fixed at 400 MHz,
It includes a band pass filter 90 with a pass band of 410 to 700 MHz and a high frequency amplifier 92. Note that switching control of the switches 76 and 78 is performed by the CPU 66.

The local oscillation section 46 of the frequency conversion means 42 is
Voltage controlled oscillator 94, programmable frequency divider 96, phase comparator 98, passband from 289.3MHz to 759MHz
．． The reference signal supplied to the phase comparator 98 is the oscillation signal of the oscillator 102 divided by the frequency divider 104. Then, in order to convert the signal under measurement to 10.7 MHz, the CPU 66 uses a programmable frequency divider 96 to change the frequency of the local oscillation signal generated by the voltage controlled oscillator 94 in the range of 289.3 MHz to 759.05 MHz. The frequency division ratio is changed.

The CPU 66 operates according to the program stored in the ROM 105, and its operations are broadly divided into manual measurement and automatic measurement. For manual measurements,
First, among the keys 106 shown in FIG. 3, the MAN key 106a
to instruct the CPU 66 that it is a manual measurement. Next, FREQ key 106b or CH key 1
06c to instruct the CPU 66 to specify the frequency or channel number of the signal to be measured, and then operate the numeric keypad 106d to set the frequency or channel number. Next, TV video/MUSE key 106e,
HDTV key 106f or TV audio/FM/DATA
The type of signal is set by operating one of the keys 106g. These set data are stored in the RAM 108. Note that these settings are performed based on the display made on the initial display screen displayed on the display unit 110. Then, when MEAS key 106h is operated, CP
U66 transmits the set frequency signal to 10.7MHz
The switches 76, 78,
A switch 51 that controls the programmable frequency divider 96 and connects one of the bandpass filters 50, 52, and 54 according to the set signal type between the mixer 44 and the amplifier 56; 53. In addition, if the TV video/MUSE key 106e is operated,
Passband is 250KHz, HDTV key 106
When f is manipulated, the passband is set to 10MHz,
When the TV audio/FM/DATA key 106g is operated, the passband is set to 600 KHz.

[0016] As a result, the signal under test becomes 10.7MH
z signal, its level is detected by a level detector 60, and converted to a digital level signal by an A/D converter 62. At this time, if the digital level is excessive, the CPU 66 switches the switches 70 and 72 to attenuate the signal under test. The digital level is corrected by this attenuated amount. The level of the signal under test measured in this manner is displayed on the display section 110. Further, when the MEMORY key 106i is operated, this digital level is stored in the RAM 108.

In the case of automatic measurement, measurement conditions are first set. Configure which amplifier input in the communal listening facility,
Is it measured at the output or branch (distribution) terminal? What type and frequency or channel number of the signal is occurring at that terminal? What is the standard level and tolerance of the signal? There is something. Since a large number of signals are generated at the above-mentioned terminals, the above settings are performed for all of these large numbers of signals. Further, since a plurality of amplifiers are provided, such settings are performed for each terminal of each amplifier. These set conditions are stored in the RAM 108 as shown in FIG.
The data is stored for each terminal of each amplifier.

Such settings are performed while the display section 110 is displaying the initial display screen, and the input, output, or branch (distribution) terminal of which amplifier is to be measured is determined by the AMPNO. shown in FIG. key 106j, IN key 106k,
OUT key 106l, BR key 106m and numeric keypad 10
6d, and the frequency to be measured or channel number is set using the FREQ key 106b or the CH key 10.
6c and numeric keypad 106d, and the signal type is set using the TV video/MUSE key 106e, HDT
V key 106f or TV audio/FM/DATA key 1
This is done by operating 06g. Also, if you press both the * key 106t and the AUTO key 106n at the same time, the TV image measurement mode will be activated, and the AUTO key 106
If only n is pressed, the mode becomes TV video and audio signal measurement mode. The standard level and allowable deviation are set by displaying them at the corresponding positions on the initial display screen by operating the numeric keypad 106d.

For automatic measurement, operate the AUTO key 106n and select AMPNO. The process is started by operating the key 106j, then operating the numeric keypad 106d to input the number of the amplifier to be measured, and then operating the MEMORY key 106i and START key 106o. As a result, the CPU 66 displays the character being measured on the display unit 110, and the first signal under measurement of that amplifier number is 10.7.
Switches 76, 7 so that the frequency is converted to MHz.
8. Controlling the programmable frequency divider and controlling the switches 51 and 53 so that one of the bandpass filters 50, 52, and 54 is selected according to the first signal under test;
Obtain the digital level signal of the first signal under test. This digital level signal is displayed on the display unit 110 together with the frequency or channel number of the first signal under test, and the type of signal, and is stored in the RAM 108. Furthermore, the CPU 66 determines whether or not it falls within an allowable range defined by the standard level and allowable deviation. If it falls within the allowable range, level measurement of the second signal under measurement is started. Also, if it is not within the allowable range, the CPU 66
The alarm buzzer 112 used as a determination means is activated and subsequent measurements are stopped. When the START key 106o is operated, subsequent signal measurements are continued. Also ALA
When the RMOFF key 106p is operated, the alarm buzzer 11
2 stops, the display disappears, and even if the START key 106o is operated, no further measurement of the level of the signal to be measured is performed.

[0020] Similarly to the condition setting for automatic measurement, AMPNO. key 106j, IN key 106k, O
Using the UT key 106l or BR key 106m,
Set one terminal of a certain amplifier, set the frequencies of a plurality of signals to be measured at this terminal using the numeric keypad 106d, and press the TV video/MUSE keys 106e, H.
After setting only one type of signal to be measured using the DTV key 106f or the TV audio/FM/DATA key 106g and operating the MAN key 106a, AMPNO.
Operate the key 106j, then operate the numeric keypad 106d to input the amplifier number, and then press the UP key 106q or DOW.
Operate the N key 106r to select the frequency of the signal under test to be measured. At this time, the selected frequency is displayed on the display section 110. Then, when the MEAS key 106h and the MEMORY key 106i are operated, the level of the signal of that frequency is measured, displayed on the display unit 110, and stored in the RAM 108. When measuring another frequency, the user operates the UP key 106q or the DOWN key 106r to select the frequency of the next signal to be measured, and then operates the MEAS key 106h and MEMORY key 106i.

Furthermore, in this embodiment, the rectifying and smoothing section 11 is installed so that this level measuring device can be used as a tester.
4 is provided on the input side of the A/D converter 62. Then, when the TESTER key 106s is operated and an AC input voltage is applied to the input terminal 116 of this rectifying and smoothing section 114, this is converted into a DC voltage by the rectifying and smoothing section 114, and A
is supplied to the /D converter 62, digitized, and sent to the CPU 6.
6 and displayed on the display section 110. Further, the digital level signal stored in the RAM 108 can be data-transmitted to an external computer or the like via the interface section 118 and the connector 120.

In the above embodiment, the variable pass band filter means 48 is composed of three band pass filters 50, 52,
54, but a configuration may also be adopted in which one band pass filter is provided and its pass band is changed. Further, in the above embodiment, two frequency converting means 42 and 82 are provided, but only the frequency converting means 42 is provided, and instead, the local oscillation section of this frequency converting means 42 is oscillated from, for example, 300 MHz to 400 MHz. It may consist of two units, one that oscillates from 400 MHz to 770 MHz.

[0023]

As described above, according to the present invention, the levels of signals of various frequencies and types can be adjusted by sequentially supplying the frequency and type of the signal under test from the input information storage means 32 to the changing means 30. can be measured. Furthermore, if the input information is automatically supplied from the input information storage means 32, the levels of signals of various frequencies and types can be automatically measured, and rapid measurements can be performed. Further, even when supplying from the input information storage means 32 by key operation, measurements can be made more quickly than when the frequency and type are manually set each time. Furthermore, by comparing the level thus measured with the permissible level range in the determining means 34, it is possible to immediately determine whether or not the measured level is normal. Furthermore, since the measured level can be stored in the storage means 36, analysis can be performed by inputting this stored value into a computer or the like. As described above, the level measuring device according to the present invention has the same functions as conventional spectrum analyzers, and has a simple configuration, so it can be miniaturized and installed at various locations in communal listening facilities. It is easy to carry, even when measuring and analyzing the levels of each amplifier in the system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the general configuration of a level measuring device according to the present invention.

FIG. 2 is a block diagram of an embodiment of a level measuring device according to the invention.

FIG. 3 is a front view of the same embodiment.

FIG. 4 is a diagram showing a part of the inside of a RAM used in the same embodiment.

FIG. 5 is a block diagram of an example of a communal viewing facility.

[Explanation of symbols]

22 Frequency conversion means 24 Pass band variable filter means 26 Level detection means 28 Display means 30 Modification means 32 Input information storage means 34 Judgment means 36 Memory means

Claims (5)

[Claims] Claim 1: Frequency converting means for converting the frequency of an input signal by mixing it with a local oscillation signal of a designated frequency; A variable passband filter means for passing a signal in the passband, a level detection means for detecting the level of the output of the filter means, a display means for displaying the output of the level detection means, and a frequency and type of the signal under measurement. is input, and the frequency of the local oscillation signal is changed according to the input frequency so that the signal under test is frequency-converted into a signal with the predetermined frequency, and the type of the signal under test that is set is changed. a changing means for changing the pass band of the variable pass band filter means according to the change means; and an input information storage means storing a plurality of pairs of frequencies and types of the signal under test to be input to the changing means. Equipped with a level measuring device. 2. The level measuring device according to claim 1, wherein the frequency and type of the signal under test are inputted from the input information storage means to the changing means when the level of one signal under test is measured. A level measuring device characterized in that the measurement is performed automatically every time the level measurement is completed. 3. The level measuring device according to claim 1, wherein the frequency of the signal to be measured is input from the input information storage means to the changing means in response to a manual key operation. Automatic level measuring device. 4. The level measuring device according to claim 1, wherein the input information storage means also stores an allowable level range corresponding to the frequency of each of the signals under test, and the input information storage means further comprises: The permissible level range corresponding to the frequency of the signal under test inputted to the changing means is supplied from the input information storage means, and determining means is provided for determining between this and the output of the level detecting means. Characteristic level measuring device. 5. The level measuring device according to claim 1, further comprising storage means for storing the output of said level detecting means.