JPH086302Y2 - Radio tester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a wireless device tester for performing a characteristic test of a wireless device, and more particularly to a wireless device tester capable of reducing unnecessary radiation to the outside.

[Prior Art] A wireless device tester can be used to measure the characteristics of a wireless device.

In recent years, as the characteristics of wireless devices themselves have improved, diversification of measurement methods and subdivision of measurement items have progressed, while there is a demand for automatic measurement of these.

These are required as a function of the radio equipment tester, and CRT
It is necessary to display various measurement results and operating procedures on a display device such as.

[Problems to be solved by the invention] However, by providing the CRT in the radio device tester, the clock signal for this CRT operation is radiated from the tube surface of the CRT, which affects the radio device to be measured, resulting in an accurate measurement. The characteristic could not be measured.

Further, inside the radio device tester, the CPU and the CRT are connected by a cable, and the clock signal in the video signal is radiated into the air while being transmitted through the cable portion,
It is a cause of unwanted radiation. Normally, the CRT and the CPU are separate units, respectively shielded by a shield case, and have a structure against noise. However, the cable portion connecting these units is not covered with the unwanted radiation.

Since harmonics are easily generated in the clock signal, it is necessary to take measures against radiation noise of unnecessary harmonic components.

Since the wireless device to be measured has high sensitivity, the sensitivity is suppressed by the radiation noise from the wireless device tester side, an accurate response cannot be made, and an accurate characteristic measurement cannot be performed.

The present invention has been made in view of the above circumstances, and provides a radio device tester capable of reducing radiation noise to the outside and accurately measuring characteristics of a radio device under test. It is an object.

[Means for Solving the Problems] In order to achieve the above object, the wireless device tester of the present invention is a CP
A control unit 3 having U11 for generating a video signal, a shielding case 7 for shielding the control unit, a display unit 5 having a CRT 27 for displaying on the CRT by the video signal, and a display unit for displaying the display unit 5. A radio equipment tester comprising a shielding case 9 which shields except a surface and a shield cable 30 which connects between the control unit and the display unit and is shielded by an external conductor 30a having a conductive outside. A low-pass filter 15 that cuts a CRT driving clock signal included in the signal at a frequency of approximately 100 MHz.

[Operation] According to the above configuration, the clock signal in the video signal is cut by the low-pass filter 15 at a predetermined frequency or higher and is supplied to the CRT.

Furthermore, a shielded cable is provided between the control unit 3 and the display unit 5.
30 allows the video signal to be transmitted in a shielded state from the outside.

As described above, even the radio equipment tester equipped with the CRT can prevent unnecessary radiation due to the clock signal in the video signal and does not generate radiation noise to the outside.

[Embodiment] FIG. 1 is a schematic view showing a radio device tester according to the present invention.

The radio device tester shown in the figure is composed of a control unit 3 and a display unit 5 which are each unitized inside the outer casing 1.

The control unit 3 is provided in the shielding case 7, and the shielding case 7 has a ground potential. Explaining the configuration inside the shielding case 7 of the control unit 3, first, a CPU 11 as a central processing unit is provided. Further, the video signal generation circuit 13 generates a video signal 14a for CRT display, a vertical synchronization signal 14b, and a horizontal synchronization signal 14c according to the control signal and data of the CPU 11. Further, the low-pass filter 15 cuts the video signal 14a output from the video signal generation circuit 13 at a frequency higher than a predetermined frequency. Here, when the clock frequency is 21 MHz, the cutoff frequency is approximately 5th order 100 MHz.

Of the LC filters used in the design of the cutoff frequency f according to the above equation, the capacitor can obtain the fifth-order frequency at 100 pF.

Here, the cutoff frequency is approximately 5 times the clock frequency.
The reason why the next 100 MHz is selected is that the clarity of the image is deteriorated at a cutoff frequency lower than this, and the radiation noise of a high frequency component is increased when a high cutoff frequency is selected.

In the opening 7a of the shielding case 7, the video signal 14
Connector 17 for a, vertical sync signal 14b, and horizontal sync signal 14c
Is provided.

On the other hand, the display unit 5 is provided in the shielding case 9, and the shielding case 9 is set to the ground potential. In the opening 9a of the shield case 9 of the display unit 5, the video signal 14a,
A connector 21 for the vertical synchronizing signal 14b and the horizontal synchronizing signal 14c is provided. The signal of the connector 21 is supplied to the CRT section video circuit 23. The CRT section video circuit 23 converts the supplied signal into characters, figures, etc., and supplies it to the CRT control section 25. The CRT control unit 25 has a high voltage power supply circuit for driving the CRT 27, and outputs a signal for screen display to the CRT 27 based on the signal from the CPU unit video circuit 23. The CRT 27 performs various displays on the tube surface 27a according to the screen display signal. This pipe surface 27a
The part is the opening 1a of the outer casing 1 and the opening 9b of the shielding case 9.
It is provided in the part.

A shielded cable is provided between the control unit 3 and the display unit 5.
Connected by 30. In the shielded cable 30, the transmission line is composed of a multi-core cable, the outer conductor 30a is a copper foil,
Alternatively, the one shielded by a metal net or the like is used. The transmission lines at both ends of the shielded cable 30 are connected to the connectors 17 and 21, respectively, and these transmission lines are the video signals 14a,
The arrangement is predetermined for the transmission of the vertical synchronizing signal 14b and the horizontal synchronizing signal 14c.

Then, as shown in the side view of FIG. 2, the outer conductors 30a are electrically connected to the shielding cases 7 and 9 at both ends of the shielded cable 30, respectively. As a result, the outer conductor 30a of the shielded cable 30 is set to the ground potential.

According to the above configuration, the control unit 3 side has a low-pass filter.
Unwanted harmonic components are cut by 15, and unnecessary harmonic components are not emitted from the CRT 27 tube surface 27a of the display unit 5.

Further, between the control section 3 and the display section 5, the internal transmission line is shield-connected by the external conductor 30a by the shield cable 30, and unnecessary radiation of this shield cable 30 portion is prevented.

FIG. 3 (a) is a graph showing radiation noise at the CRT27 tube surface 27a portion by the radio equipment tester having the above configuration, and FIG. 3 (b) shows the shielded cable 30,
CR by radio equipment tester without using low-pass filter 15
It is a graph which shows the radiation noise in a T-tube surface part.

As is clear from these graphs, the radio device tester according to the present invention was able to significantly reduce radiation noise.

[Advantages of the Invention] According to the present invention, noise countermeasures are taken inside the radio equipment tester that cause unnecessary radiation, so that radiation noise to the outside can be reduced.

As a result, the characteristics of the measured radio device can be measured accurately and with high accuracy without giving radiation noise to the measured radio device side.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a radio device tester according to the present invention, FIG. 2 is a side view showing an end of a shielded cable, and FIG. 3 (a) is a graph showing radiation noise of the radio device tester.
FIG. 3B is a graph showing the radiant noise of the wireless device tester without noise countermeasures. 1 ... Outer housing, 3 ... Control part, 5 ... Display part, 7, 9 ...
Shielding case, 7a, 9a ... Opening, 11 ... CPU, 13 ... Video signal generation circuit, 14a ... Video signal, 14b ... Vertical sync signal, 14c ... Horizontal sync signal, 15 ... Low pass Type filter, 17, 21 …… Connector, 23 …… CRT video circuit, 25 ……
CRT control section, 27 …… CRT, 27a …… Pipe surface, 30 …… Shielded cable, 30a …… Outer conductor.

Claims (1)

[Scope of utility model registration request] 1. A control unit (3) having a CPU (11) for generating a video signal, a shielding case (7) for shielding the control unit, and a CRT (27), wherein the video signal is used. CRT
A display unit (5) for displaying, a shielding case (9) for shielding the display unit except the display surface thereof, and an outer conductor (30a) for electrically connecting the control unit and the display unit. In a radio equipment tester consisting of a shielded cable (30) shielded by, a low-pass filter (15) that cuts a clock signal for CRT drive included in a video signal in the control unit at a frequency of approximately 100 MHz, A wireless device tester having: