JPS6124939Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a spectrum analyzer, and specifically aims to provide a spectrum analyzer that can simultaneously display spectra under different setting conditions on the same display screen and compare their mutual relationships. It is.

As is well known, a spectrum analyzer is used, for example, to display the frequency characteristics of a high frequency filter or to display the frequency spectrum of radio waves. When adjusting the frequency characteristics of a high frequency filter, for example, it is convenient to be able to simultaneously display the entire frequency characteristic and an enlarged portion of the frequency characteristic. There are also cases where it is convenient to be able to display frequency characteristics and phase characteristics at the same time.

In this way, when displaying the entire frequency characteristic or enlarging a part of it, it is necessary to change the width of the sweep frequency, change the bandwidth of the intermediate frequency amplifier, or change the gain. Furthermore, the circuit configurations are different when displaying frequency characteristics and when displaying phase characteristics, and it is generally considered that these different states cannot be displayed at the same time.

The purpose of this invention is to provide a spectrum analyzer that can simultaneously display displays under various conditions as described above.

This invention is configured so that the conditions of each part of the spectrum analyzer can be set using electrical signals, and the condition setting signal can be read out from the memory, and the conditions of each part can be set using the read signal. It is composed of

Therefore, according to this invention, by changing the conditions every time the cathode ray tube used as an indicator is swept,
For example, it is possible to alternately display a state in which the entire frequency characteristic is displayed and a state in which a part thereof is enlarged, and as a result, the two states can be displayed simultaneously by using an afterglow characteristic or the like.

An embodiment of this invention will be described below in detail with reference to the drawings.

The example shown in the figure shows a case where the frequency characteristics of an object to be measured 105 such as a filter is displayed. In the figure, 101 is a local oscillator. Local oscillator 101
The constant frequency signal is frequency-mixed with the sweep signal of the sweep oscillator 102 in the frequency mixer 103 and outputs, for example, the sum component to the output terminal 104. The sweep signal output to the output terminal 104 is applied to the object to be measured 105, and is supplied to the input terminal 106 through the object to be measured 105. Input terminal 10
The signal supplied to 6 is converted into a low frequency signal by the sweep signal of the sweep oscillator 102 in a frequency mixer 107, and is converted into an intermediate frequency signal 1 of a constant frequency.
Get 08. The intermediate frequency signal is sent to intermediate frequency amplification circuit 1.
09, detected by a detector 111, and sent to a cathode ray tube display 113 through a mode changeover switch 112.
is supplied to the Y-axis input terminal of Cathode ray tube display 1
The lamp voltage generator 114 is connected to the X-axis input terminal 13.
A lamp voltage is supplied from the source, and the electron beam is swept in the X-axis direction. With this configuration, the frequency characteristics of the object to be measured 105 are displayed on the cathode ray tube display 113. When the switch 112 is switched to the fixed contact b side, the phase comparison output is given from the phase comparator 115 to the Y-axis input terminal of the cathode ray tube display 113, and the phase characteristics of the object to be measured 105 are displayed on the display 113. Ru.

The description up to this point is the configuration of a spectrum analyzer that has been well known in the past.

In this invention, the setting conditions of the lamp voltage generator 114 and the intermediate frequency amplifier 109 can be set by electrical signals.

The intermediate frequency amplifier 109 includes various bandpass filters 116a, 116b...1 having different bandwidths.
16n are provided, and by selecting one of these, it is possible to select whether to display the entire frequency characteristic of the object to be measured or to enlarge and display a part of the frequency characteristic. This selection is made in relation to the amplitude of the lamp voltage and the DC bias voltage to be superimposed thereon. Conventionally, this bandpass filter 116a,
The selection of 116b...116n is performed by a manual switch, but in this invention it is configured to be switched by an electric signal. For this purpose, register 117 and FET switches 118a and 118 are required.
b...118n is provided, and FET switches 118a, 11 are connected to the register 117 from the microcomputer 119 via the input/output interface 121.
8b...118n selection signals are applied to turn on any one of the FET switches.

Gain control amplifiers 112a to 112n are provided after each of the bandpass filters 116a to 116n, and a digital signal output from the microcomputer 119 is converted into an analog signal by a DA converter 123, and the analog signal is transmitted to each gain control amplifier. 122a to 122n, and the gain can be set electrically.

On the other hand, the ramp voltage generator 114 is provided with a ramp signal source 124 and a DA converter 127.
24 to the adder circuit 126 through the gain adjustment circuit 125 and the DA converter 12
A bias voltage with a desired value is given from 7,
Added to ramp signal. The sweep center frequency of the sweep oscillator 102 is set by this bias voltage. A control signal 128 is also given to the gain adjustment circuit 125 from the input/output interface 121, and the amplitude of the ramp signal is set by this control signal 128. The sweep bandwidth of the sweep oscillator 102 is set by setting this amplitude.

A keyboard 129 is connected to the input/output interface 121, and setting conditions for each section can be input from the keyboard 129. The setting conditions are stored in memory.

In this invention, the setting conditions of each part are stored in a memory separately for different conditions, and the different setting conditions are read out alternately and each part is set by the read output.

This example shows a case in which two memories 131 and 132 are provided and different conditions are stored in the two memories 131 and 132. For example, the memory 131 stores conditions for displaying the entire frequency characteristic of the object to be measured 105, and the memory 132 stores conditions for displaying a portion of the frequency characteristics in an enlarged manner. The memories 131 and 132 are switched by the falling signal 201 (FIG. 2A) of the ramp signal source 124, and when the reading is completed and the conditions from the memory 131 or 132 are set in each setting section, Ramp signal 2 as shown in Figure 2A
02 is set to rise. Therefore, a start signal 203 (FIG. 2B) is applied to the ramp signal source 124 from the input/output interface 121.
Further, when displaying the frequency characteristics and the phase characteristics at the same time, the switch 112 may be operated in synchronization with the switching between the memories 131 and 132.

The cycle of the lamp voltage is appropriately set in consideration of the afterimage characteristics of the display 113 so that two different frequency characteristics that are switched for each sweep of the display are displayed at the same time.

As explained above, according to this invention, each setting section can be controlled by electrical signals, and the condition settings can be read and set from the memories 131 and 132, so that the condition setting memories 131 and 1
It can be alternately changed by the read signal from 32. Since the setting conditions are changed by the microcomputer 119, the setting conditions can be changed in a short time. Therefore, since the setting conditions can be changed each time the cathode ray tube display 113 is horizontally swept, the results may appear to be different depending on the afterimage characteristics of the display, as shown in FIG. 3, for example. can be displayed at the same time. In FIG. 3, 301 shows the overall frequency characteristics of the bandpass filter, and 302 shows the enlarged characteristics.

Therefore, this invention is suitable for use in, for example, adjusting the frequency characteristics or phase characteristics of a filter.

Although the memories 131 and 132 have been described as separate memories, the write addresses may be changed in the same memory. Further, the switching between the memories 131 and 132 may be performed not every one sweep but every two sweeps.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of this invention. FIGS. 2 and 3 are waveform diagrams for explaining the operation of this invention. 102: Sweep oscillator, 109: Intermediate frequency amplifier, 113: Display, 114: Lamp voltage generator, 117: Register, 123: DA converter, 1
24: lamp signal source, 119: microcomputer, 121: input/output interface, 13
1,132: Memory.

Claims (1)

[Scope of utility model registration request] There is a lamp voltage generator that can set the amplitude and frequency of the lamp voltage and the DC voltage superimposed on the lamp voltage using electric signals, and the oscillation frequency is swept by the lamp voltage output from this lamp voltage generator. a sweep oscillator, a first frequency mixer for obtaining an intermediate frequency signal of a constant frequency of the sum or difference of the frequencies of the sweep signal of the sweep oscillator and the input signal; and the output of the first frequency mixer is supplied;
An intermediate frequency amplifier whose bandwidth, gain, etc. can be changed by a control signal, a detector that detects the output of the intermediate frequency amplifier, and a local oscillator.
a second frequency mixer that frequency mixes the oscillation output of the local oscillator and the output of the sweep oscillator and outputs a test signal; and a phase that detects a phase difference between the output of the intermediate frequency amplifier and the output of the local oscillator. a comparator, a mode changeover switch that switches between the output of the phase comparator and the output of the detector, a cathode ray tube display that displays the output taken out by the mode changeover switch, the lamp voltage generator, and a microprocessor capable of supplying a setting signal to an intermediate frequency amplifier, setting and switching the states of the lamp voltage generator and the intermediate frequency amplifier, and controlling the switching of the mode changeover switch; means for transmitting the fall of the lamp voltage of the generator to the microprocessor; a memory in which two different sets of setting signals for the lamp voltage generator and the intermediate frequency amplifier are set and stored; The measurement switching means alternately applies the two sets of setting signals in the memory to the lamp voltage generator and intermediate frequency amplifier, and two characteristic displays are simultaneously displayed on the cathode ray tube display by switching the settings. Spectrum analyzer where the frequency of the above lamp voltage is set so that