CN1241885A - Apparatus and method for determining location of interference source and for measuring interference signal emitted therefrom - Google Patents

Abstract

An apparatus and method for determining the location of an interference source and measuring at least one signal characteristic of at least one external signal emitted by the interference source in a cellular mobile telecommunication system, wherein the apparatus comprises: an antenna for detecting the at least one external signal a motor, used to drive the antenna to rotate; a low noise amplifier, used to amplify the at least one external signal detected by the antenna; a spectrum analyzer, used to measure the at least one signal characteristic of the amplified signal; and control processing device for controlling the motor and the spectrum analyzer.

Description

Apparatus and method for determining the location of an interference source and measuring an interference signal of an interference source

This application claims priority to Patent Application Serial No. 98-26411 entitled "Apparatus and Method For Measuring Interference Source" filed with the Korean Industrial Property Office on July 1, 1998 rights, the contents of which are listed here for reference.

The present invention generally relates to a cellular mobile telecommunication system, and in particular to a device and method for determining the position of an interference source and measuring the interference signal sent by the interference source.

The cellular mobile telecommunication system divides the entire service area into multiple cells, and each cell is served by a base station. With a base station placed in the center of each cell, users can communicate with each other as they move between cells. The design of the cellular system enables a mobile station to continue a call as it moves out of a cell served by one base station and into another cell served by another base station. Furthermore, this design structure with respect to service area division into multiple cells makes it possible to reuse the same frequency. This improves frequency usage efficiency and enables the system to accommodate more users. For example, a mobile telecommunication system employing Code Division Multiple Access (CDMA) technology transmits a signal on a carrier by multiplying it by an inherent code and by extending the bandwidth before transmitting the signal to each user sharing the same frequency.

The performance of CDMA systems is often degraded due to interference generated by various sources. For example, signals between neighboring base stations cause cross-interference. However, in mobile telecommunication systems, cross-interference caused by signals between adjacent base stations is generally minimized by appropriate selection of the location of each base station. This is important in optimizing CDMA system performance. Therefore, when selecting the location of the base station, an external interference signal with a specific frequency band is measured in order to locate the base station at a position where the base station is least affected by the interference signal.

US Patent No. 3,783,448 entitled "Apparatus For Measuring Electromagnetic Radiation" discloses an apparatus for measuring electromagnetic radiation using an antenna and a detector for receiving electromagnetic waves. However, this arrangement, known as other prior art devices, does not fully determine and measure at the base station the source and strength of interfering signals occurring within the mobile telecommunication system.

The present invention seeks to provide an apparatus and method for determining the position of a source of interference emitting an interference signal or an external signal and measuring at least one signal characteristic of the interference signal using a directional antenna rotated by a motor.

The device according to a preferred embodiment of the present invention includes: an antenna for detecting the at least one external signal; a motor for driving the antenna to rotate; a low-noise amplifier for performing the at least one external signal detected by the antenna an amplification; a spectrum analyzer for measuring the at least one signal characteristic of the amplified signal; and a control processor for controlling the motor and the spectrum analyzer.

Preferably the antenna is a directional antenna. In addition, the antenna is preferably a YAGI antenna. Furthermore, it is preferable that the antenna has a narrow beam width. Preferably, the low noise amplifier has a gain greater than 35dB.

The motor rotates the antenna by a predetermined rotation angle according to the beam width of the antenna, and sends information on the rotation angle to the control processor. The control processor determines the azimuth/time relationship relative to the motor, and obtains the measured signal strength at the corresponding time azimuth from the spectrum analyzer, and displays the measured signal strength on the screen according to the azimuth/time relationship.

A preferred method of the present invention comprises the steps of: receiving the at least one external signal by an antenna; amplifying the received external signal by a low noise amplifier; analyzing the amplified signal by a spectrum analyzer; and using the interference direction-power intensity ratio to represent the analytical signal. The method also includes the steps of: rotating the directional antenna; converting the rotational speed of the directional antenna into an azimuth; and measuring and analyzing the power intensity of the signal according to each azimuth.

Preferably, the low noise amplifier has a gain greater than 35dB. Furthermore, preferably, the step of analyzing the signal in terms of interference direction-to-power intensity ratio shows overlapping results regardless of the measurement period.

With reference to the following detailed description of the present invention with reference to the accompanying drawings, the above-mentioned purpose, features and advantages of the present invention will become more clear, in the accompanying drawings:

Fig. 1 is the block diagram that the present invention is used for determining the position of the interference source that sends out interference signal and the device of measuring interference signal strength;

Figure 2 is a graph representing the location and magnitude of the interferer measured by the present invention; and

FIG. 3 is a flow chart of the method for measuring the strength of an interference signal sent by an interference source according to the present invention.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, well-known functions and constructions will not be described in detail since it might obscure essential details.

The present invention provides a directional antenna that can locate the location of an interference source that emits an interference signal that interferes with a signal emitted by a base station system. The invention also provides a method of determining the location of an interference source emitting an interference signal and measuring the strength of the interference signal.

In the present invention, the signal strength received by the directional antenna is measured, and the measurement result is displayed on the screen or monitor. The results are preferably represented graphically on the screen, showing the direction and magnitude of the interfering signal. This graph can be used to determine the cell plan of the mobile telecommunications system and to determine where to place base stations in the system.

FIG. 1 shows the structure of a device according to the invention for determining the position of an interference source emitting at least one interference signal and for measuring the strength of the interference signal. As shown in Figure 1, this device comprises: antenna 100, is used for detecting external signal; Motor 200, is used for rotating this antenna; Low noise amplifier (LNA) 300, is used for amplifying the signal detected by antenna; Spectrum analyzer 400 , for measuring signal characteristics, such as propagation direction, amplitude, and frequency of the amplified signal; and a control processor 500, for controlling the motor and the spectrum analyzer.

The operation of the device of the present invention will be described below with reference to FIGS. 2 and 3 . The antenna 100 that measures at least an external signal is preferably a directional antenna, and more specifically, the antenna 100 is preferably a YAGI antenna with a narrow beam width. The motor 200 is preferably a stepper motor which rotates the YAGI antenna by a specific angle relative to the beam width of the YAGI antenna. If the period of rotation of the antenna 100 is known, the angle at which the signal level and amplitude are measured after the first rotation can be determined. For example, if the rotation period is 4 seconds, the signal level measured over 1 second is the signal level in the 90° direction, and the signal level measured over 2 seconds is 180. signal level in the direction.

The low noise amplifier 300 amplifies the signal according to the noise power level of the spectrum analyzer 400 . That is, the low noise amplifier 300 amplifies the signal level of the input signal to a signal level measurable by the spectrum analyzer 400 . The bandwidth of the low noise amplifier 300 is preferably able to amplify the most suitable frequency band to be measured, ie the frequency band used by the mobile telecommunication system; moreover, the gain of the low noise amplifier 300 is preferably greater than 35dB. The AC/DC converter 600 converts AC (alternating current) input into DC (direct current). The AC/DC converter also steps down the voltage to an appropriate level to provide an appropriate voltage to the motor 200 and the low noise amplifier 300 .

Referring to FIG. 1, the control processor 500 includes a PCMCIA (Personal Computer Memory Card International Association)-GPIB (General Purpose Interface Bus) card, which controls the motor 200 through the parallel cable 2, and controls the spectrum analyzer 400 through the GPIB1. The control processor 500 converts the rotational speed of the motor 200 into an azimuth/time relationship, ie the azimuth under the hour and minute readings on the clock face, and determines the signal level measured by the spectrum analyzer 400 at each time azimuth. The control processor 500 measures the time orientation when the motor 200 is rotating, and obtains the signal strength measured at each corresponding time orientation from the spectrum analyzer 400 . The measured signal strength is displayed on the screen or monitor by bearing. Therefore, signal level measurements and corresponding bearings are known simultaneously for each measurement. Thus, by displaying signal level measurements and their corresponding azimuths, the user can determine the interference level at each time azimuth.

As described above, the interference signal strength measured by the structure shown in FIG. 1 is displayed on the screen of the control processor 500 . Figure 2 shows the location and magnitude of the interferer and the signal, respectively, measured according to the present invention. As shown in Figure 2, signal interference is measured along a 360° circle, thereby measuring signal strength in all directions. Signal strength can be determined by measuring the amplitude at various locations and using FIG. 2 . For example, it was determined that the interference is strongest in signal directions 10 and 20 because the amplitudes are greatest in these directions. Therefore, it can be concluded that there are sources of interference in signal directions 10 and 20 .

FIG. 3 shows a flow chart of the method according to the invention for determining the location of an interference source and for measuring the strength of an interference signal emitted by this interference source. The measured information can be used to correctly determine where to place base stations in the cellular system where they are least affected by interference. The method comprises the steps of: receiving at least one external signal (S10) by a directional antenna; amplifying the received signal (S20) by a low noise amplifier with a predetermined gain; analyzing the amplified signal (S30) by a spectrum analyzer; - Power intensity ratio to represent the analyzed signal.

Preferably, the method further includes the steps of: driving the directional antenna to rotate (S50) by a separate rotating device and a separate control device; and transforming the rotational speed of the directional antenna into an azimuth/time relationship, and measuring each Signal strength in time orientation (S60). Preferably, the overlapping result is expressed in the step of expressing the analysis signal using the interference direction-power intensity ratio regardless of the measurement period.

Accordingly, the present invention provides an apparatus and method for determining the location of an interference source and measuring the signal strength of an interference signal emitted by the interference source. The device uses a motor to drive the directional antenna to rotate according to the instructions sent by the control processor. The apparatus and method of the invention can be used to determine the location of base stations during the design of a cellular mobile telecommunication system by providing information about the weakest and strongest interfering directions and interfering signal magnitudes over a 360° circle.

Although the embodiment has been described in detail by way of example with reference to the accompanying drawings, the present invention can be modified and replaced in various forms. It should be understood that the invention should not be limited to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Claims (20)

1. be used for the device that definite position of interference source is also measured at least one signal characteristic of at least one external signal of being sent by this interference source in a cellular mobile telecommunication system, described device comprises:

Antenna is used to detect described at least one external signal;

Motor is used to drive described antenna rotation;

Low noise amplifier, be used for to by described antenna detection to described at least one external signal amplify;

Spectrum analyzer is used to measure described at least one signal characteristic of amplifying signal; With

Processor controls is used to control described motor and described spectrum analyzer.

2. device as claimed in claim 1, wherein said antenna is a directive antenna.

3. device as claimed in claim 1, wherein said antenna are the YAGI antennas.

4. device as claimed in claim 1, wherein said antenna has narrow beam width.

5. device as claimed in claim 1, wherein said motor is scheduled to the anglec of rotation according to the beamwidth of antenna with described antenna rotation, and sends the information of the relevant anglec of rotation to described processor controls.

6. device as claimed in claim 1, wherein said processor controls are determined the orientation/time relationship with respect to described motor, and obtain at least measurement result on corresponding time aziniuth of described at least one signal characteristic from described spectrum analyzer.

7. device as claimed in claim 6, wherein said processor controls will be presented on the screen in measurement result on corresponding time aziniuth at least.

8. device as claimed in claim 7, wherein said screen display be described at least measurement result of described at least one signal characteristic of the position of interference source and described at least one external signal.

9. device as claimed in claim 1, wherein said at least one signal characteristic comprises the amplitude of described at least one external signal.

10. device as claimed in claim 1, the gain of wherein said low noise amplifier is greater than 35dB.

11. device as claimed in claim 1, wherein said motor is a stepping motor.

Also measure the method for at least one signal characteristic of at least one external signal of being sent by this interference source 12. be used for determining position of interference source in the cellular mobile telecommunication system, described method comprises the steps:

Receive described at least one external signal by directive antenna by the driven by motor rotation;

By low noise amplifier received external signal is amplified;

Analyze amplifying signal by spectrum analyzer; With

Analytic signal is presented on the screen, wherein said screen display be at least measurement result of described at least one signal characteristic of the position of interference source and described at least one external signal.

13. method as claimed in claim 12, wherein said analytic signal recently shows with interference radiating way-power level.

14. method as claimed in claim 12, wherein said method also comprises the steps:

The rotary speed of described directive antenna is transformed into orientation/time relationship; With

Described at least one signal characteristic of measurement analytic signal on corresponding time aziniuth.

15. method as claimed in claim 12, the gain of wherein said low noise amplifier is greater than 35dB.

16. method as claimed in claim 13, wherein said with analytic signal be presented at step on the screen comprise show overlapping result and no matter measuring period step how.

17. method as claimed in claim 12, wherein said at least one signal characteristic comprises the amplitude of described at least one external signal.

Also measure the device of at least one signal characteristic of at least one external signal of being sent by this interference source 18. be used for determining position of interference source in the cellular mobile telecommunication system, described device comprises:

Be used to detect the checkout gear of described at least one external signal;

Be used to drive the whirligig of described checkout gear rotation;

Be used for the amplifying device that amplifies by detected described at least one external signal of described checkout gear;

Be used to measure the measurement mechanism of described at least one signal characteristic of amplifying signal; With

Be used to control the control device of described whirligig and described measurement mechanism.

19. device as claimed in claim 18, wherein said checkout gear is a directive antenna.

20. device as claimed in claim 19, wherein said whirligig rotates predetermined angular according to the beamwidth of antenna with described antenna, and sends the information of the relevant anglec of rotation to described control device.

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