JPH09289482A - Fault detection method and device for radio system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna breakage detection method which is available regardless of types of used antennas and also can be applied to a reception-only branch by calculating the time average at every fixed time between the highest reception level and a reception level excluding the highest one among the reception levels of input signals and then detecting a fault of a radio system when the value obtained through subtraction carried out among the time averages is larger than the prescribed threshold. SOLUTION: The reception levels are almost equal to each other at the same time point among the signals which are received at the reception parts 1 to 4 via antennas ATN1 to ATN4 of a PHS base station. On the other hand, the reception level of the signal received at the reception part via a broken antenna is lower than that of the signal received via a normal antenna. A demodulation part 5 includes a circuit which detects the reception part that receives the highest reception level. Then the breakage of an antenna can be decided if a non-selected reception part is detected based on the detection result of the said circuit of the part 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna damage detection method used in, for example, a PHS (Personal Handyphone System).

First, one PHS base station is designed to cover a service area with a radius of several hundred meters. For this reason, a large number of PHS base stations are installed at intervals of several hundred meters, but the installation location is mainly for utility poles, telephone boxes, rooftops of buildings, etc. Maintenance personnel inspect each PHS base station one by one. Is difficult.

Also, since the number of base stations installed in the same area can be reduced by enlarging the service area, it is a means for enlarging the transmission output and enlarging the service area in an area where there are few telephone calls. It is used.

However, since the transmission output of the PHS terminal used by the user is constant, the reception sensitivity commensurate with the increase in the transmission output is set to PH.
S Base station must be equipped. For this reason, there is also a type in which a dedicated reception antenna is provided to increase the number of combined diversity reception sections, and thereby a desired reception sensitivity is obtained.

Here, if the antenna of the PHS base station is damaged, the transmission output and the reception sensitivity of the PHS base station are significantly deteriorated, so that the base station is likely to fall into a state where it cannot cover its service area. .

Therefore, some PHS base stations have a function of constantly monitoring the state of the antenna and notifying the PHS maintenance system when the antenna is damaged.

[0007]

2. Description of the Related Art As a conventional antenna damage detection method,
When the antenna is damaged, VSWR (Volta
ge Standing Wave Ratio)
There is a method of measuring the reflected power when the local station transmits, and when the measured reflected power exceeds a predetermined threshold value, an alarm is sent out indicating that the antenna is damaged.

As another method, a direct current resistance between the signal line of the antenna and the ground is 0 or close to 0 is used as an antenna, a direct current is passed between the signal line and the ground, and the direct current is cut off. There is a method of sending out an alarm when the antenna is damaged when it becomes.

[0009]

Among the above-mentioned antenna damage detection methods, the method of measuring the reflected power transmitted by the local station cannot be implemented unless the antenna can be transmitted, and is used only for reception. Not applicable to antennas.

Further, the method of utilizing a direct current is subject to the condition that the direct current resistance between the signal line of the antenna and the ground is 0 or close to that, which limits the antenna used.

An object of the present invention is to provide an antenna breakage detecting method applicable to a receive-only branch regardless of the type of antenna used.

[0012]

FIG. 1 is a diagram for explaining the principle of the first invention, and FIG. 2 is a diagram for explaining the operation of FIG. SW1,
SW2 and SW5 are switches.

According to the first aspect of the present invention, of the reception levels of the signals input via the respective antennas, the maximum reception level and the reception levels other than the maximum reception level are averaged at regular intervals to obtain a time average. .

Then, when the value obtained by subtracting the time average of the reception levels other than the maximum reception level from the time average of the maximum reception levels is equal to or more than a preset threshold value, it is detected as a fault of the wireless system.

According to the second aspect of the present invention, when all the antennas are damaged, the transmitting / receiving antenna detects the reflected wave as a fault of the radio system when the reflected wave exceeds a predetermined amount. The third aspect of the present invention integrates the number of selections for each antenna selected as the maximum reception level among the reception levels of the signals input via each antenna for a certain period of time.

Then, when the number of integrated selections for each antenna is less than or equal to a preset threshold value, it is detected as a fault in the wireless system. In the fourth aspect of the present invention, when all the antennas are damaged, the antenna for both transmission and reception is detected as a fault of the wireless system when the reflected wave is a predetermined amount or more.

According to a fifth aspect of the present invention, a first maximum reception level extracting means for extracting a maximum reception level among the reception levels of signals input through the respective antennas, the extracted maximum reception level and the maximum reception level. Averaging means is provided for averaging the reception levels other than the levels at regular time intervals to obtain the time average of the maximum reception level and the reception levels other than the maximum reception level.

From the time average of the maximum reception level,
When the value obtained by subtracting the time average of the reception levels other than the maximum reception level is equal to or greater than a preset threshold value, the wireless system is detected as a fault.

According to a sixth aspect of the present invention, second maximum reception level extraction means for transmitting the antenna as a selection result when the maximum reception level is extracted from the reception levels of the signals input through the respective antennas, and input An antenna-specific selection number accumulating portion for accumulating the number of selections for each antenna is provided using the selection result.

Then, when the integrated selection count for each antenna output by the selection count integration means for each antenna is less than or equal to a preset threshold value, it is detected as a fault in the wireless system.

Now, the principle of the first invention will be described with reference to FIGS. 1 and 2. For example, two branches of ANT1 and ANT2 are used as transmitting and receiving antennas of the PHS base station, and ANT3 and ANT4 are used as receiving antennas. 2 branches are provided.

When all the antennas are normal, the reception levels of the signals received by the receiving section 1 to the receiving section 4 via the corresponding antennas have almost the same value at the same time. However, a slight difference occurs in the reception level due to the installation condition of the antenna and the relationship of the propagation path between the PHS base station and the PHS terminal (not shown) that has transmitted the reception signal.

On the other hand, when the antenna is damaged, the reception level of the signal received by the receiving unit via the damaged antenna is lower than that when the antenna is normal. For example,
When the antenna ANT4 is damaged as shown by the cross mark in Fig. 1, as shown in Fig. 2 (a), the reception level of the signal received by the receiving unit 1 to receiving unit 3 via the normal antennas ANT1 to ANT3. 1
Compared to ~ 3, the receiving unit 4 via the damaged antenna ANT4
The reception level 4 of the signal received by is low.

When the antennas ANT3 and ANT4 are damaged (not shown), a normal antenna AN is displayed as shown in FIG. 2 (b).
Compared to the reception levels 1 and 2 of the signals received by the receiving unit 1 and the receiving unit 2 via T1 and ANT2, the damaged antennas ANT3 and ANT4
The reception levels 3 and 4 of the signals received by the receiving unit 3 and the receiving unit 4 via the low level have low values.

In this way, the damage to the antenna can be detected by directly monitoring the decrease in the reception level of each receiving section. Further, the PHS base station normally performs diversity combining reception. In this diversity combination reception, the reception level of the signal received by each reception unit is referred to, and the reception unit is selected or combined.

For this reason, a circuit (not shown) is provided inside the demodulation unit (DEM) 5 for detecting the reception unit having the maximum reception level. Therefore, if there is a receiving section that is not selected using this detection result, it is possible to determine that the antenna is damaged based on the detection result.

However, in these methods, when all the antennas are damaged, the reception level of the signal received by each antenna is lowered overall, so that all the antennas are selected evenly, and the antennas are damaged. I do not know that I did. Therefore, it is necessary to use it together with a method of monitoring the reflected wave of the transmitted wave.

By using such a method, it becomes possible for the maintenance system to grasp the antenna damage status of a large number of PHS base stations installed.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 is a block diagram of the first and second embodiments of the present invention, FIG. 4 is a block diagram of a main part of a reception level difference detecting section in FIG. 3, and FIG. 4, a block diagram of an embodiment of the present invention,
FIG. 6 is a configuration diagram of a main part of the branch selection number integration circuit in FIG.

The same reference numerals denote the same objects throughout the drawings. Further, the maximum reception level extraction circuit 521 in FIG.
Is also configured to output the maximum reception level and the antenna information that has reached the maximum reception level. Furthermore, in the following description, the receiving unit is a branch.

Here, FIG. 4 shows the reception level RS of the branch 3.
In the figure of one embodiment of the method for detecting the antenna damage by detecting the reception level difference between SI3 and the reception level RSSI4 of the branch 4, the reception level difference between the reception level RSSI1 of the branch 1 and the reception level RSSI2 of the branch 2 is detected. A method for detecting the antenna damage is not shown.

3 to 6 will be described below. The parts described in detail above will be outlined and the parts of the present invention will be described in detail. Branches 1 to 1 enclosed by dotted lines in FIG. Since the reception operation of the branch 4 is the same, the operation description of the branch 1 will be representative.

In the figure, ANT1 and ANT2 are antennas for both transmission and reception, and ANT3 and ANT4 are antennas for reception only. First, the 1.9 GHz band received signal (π / 4 shift QPSK wave) received by the antenna ANT1 of the branch 1 in FIG. 3 is added to the first frequency converter MIX1 through the switch SW1 and the band pass filter BPF. .

Since the first local oscillator signal (not shown) is also added here, the frequency of the received signal is converted to the first intermediate frequency and then the unnecessary wave is suppressed through the band pass filter BPF '. After that, it is added to the second frequency converter MIX1 '.

Since the second local oscillator signal (not shown) is also added to the second frequency converter MIX1 ', the received signal of the first intermediate frequency is converted into the second intermediate frequency, and then the band pass filter BPF ", It is amplified to a predetermined level through the intermediate frequency amplifier IF AMP and added to the demodulator 51.

Therefore, the demodulator 51 demodulates the received signal of the second intermediate frequency and extracts the demodulated data. Further, the intermediate frequency amplifier IF AMP sends the obtained reception level (RSSI1) to the reception level difference detection unit 52.

In the branches 2 to 4, similarly to the branch 1, the received signal frequency-converted to the second intermediate frequency is sent to the demodulator 51, and the received levels RSSI2 to RSSI4 are sent to the received level difference detector 52, respectively. Send out.

The reception level difference detection unit 52 has a structure as shown in FIG. 4, and the reception level RSSI of each input branch is received.
1 to RSSI4 are added to the maximum value level extraction circuit 521.
The operation of this circuit depends on, for example, the reception levels RSSI1 and RSSI2.
And the receiving levels RSSI3 and RSSI4 are compared to determine the larger receiving level, and then the two receiving levels that have been determined are compared to determine the maximum receiving level (which is the instantaneous value. ) Is extracted and sent to the averaging part 522.

Therefore, the averaging section 522 averages the received maximum level received levels at regular time intervals (for example, 1 second), and calculates the averaged maximum level * RSSI _MAX as the first and second levels. Output to the subtraction parts 525 and 526 of.

On the other hand, the reception levels RSSI3 and RSSI4 are similarly averaged every fixed time (for example, 1 second), and the averaged reception levels * RSSI3 and * RSSI4 are subtracted from the corresponding subtraction part 52.
Output to 5,526.

The first and second subtraction parts 525 and 526 are (* RSSI
_{MAX - * RSSI3), (*} RSSI MAX - * RSSI4) calculates the added calculation results to the first, second comparator 527, 528. A threshold value X is added to these comparators, and if the subtraction result is greater than or equal to the threshold value, the detection result of antenna damage is sent out via the OR gate 529.

The configuration shown in FIG. 4 has each reception level RSSI.
Is averaged in the averaging part, but this circuit can be replaced with a maximum hold circuit (MAXHOLD). Also, PH
In the case of S, since the time division duplex (TDD) system is adopted, it is used for both transmission and reception instead of the transmission only antenna as shown in FIG.

Now, at the transmission timing, the output from the transmission circuit 61 is transmitted from the antenna ANT1 via the antenna changeover switches SW5 and SW1.
It passes through 62 and is detected by the detector 63 and added to the comparator 64. Since a threshold value is added to the detector 63, the detection result of antenna damage is sent out if the threshold value is exceeded.

Here, since the reflected wave may not be seen depending on how the antenna is damaged, a similar maximum holding circuit may be applied to the branches 1 and 2, and the reflected wave detection method may be used supplementarily. It is possible.

Further, in order to make averaging and maximum value retention more reliable, the operating time of these parts may be limited to only during a call (the reason will be described later). FIG. 5 shows an embodiment of a method for detecting antenna damage using the branch selection result.

As described above, the demodulation unit 5 includes the maximum reception level extraction circuit 521. This maximum value reception level extraction circuit selects the branch having the maximum reception level,
Since the branch selection result (including antenna information) is output, this selection result is sent to the branch selection number integration circuit 7 connected to the demodulation unit.

Here, the integration time generation circuit 76 in the branch selection number integration circuit shown in FIG. 6 receives, for example, the integration enable signal for a certain period of time when the call status signal indicating the call status is input. In addition to the integration part 71 and the branch 4 selection number integration part 72, the integration is enabled.

Therefore, the branch 3 selection number accumulating portion 71 shows the branch 3 selection result among the input branch selection results, and the branch 4 selection number integrating portion 72 shows the branch 4 selection result among the input branch selection results. Each is integrated, but when the applied integration enable signal is cut off, integration is stopped and the integrated value up to this point is applied to the corresponding comparator.
Add to 73, 74.

The comparators 73 and 74 compare the magnitude of the applied common threshold value X ₂ and the input integrated value. If the comparison result is smaller than the threshold value X ₂ , that is, if the antenna connected to the branch is not selected X ₂ times or more within a certain period of time, the antenna connected to the branch is considered to be damaged and the antenna damage is detected. The result is sent out via the OR gate 75.

When not in a call, the selected result is due to noise and is not accurate, so it must be ignored. Further, although the circuit of FIG. 6 applies only the branch 3 and the branch 4, the same circuit can be applied to the branch 1 and the branch 2, and the reflected wave detection method can be used supplementarily. is there.

That is, regardless of the type of the antenna used, the device can detect the antenna damage detection even in the reception-only antenna, so that the maintenance of the antenna becomes easy.

[0052]

As described in detail above, according to the present invention, it is possible to provide an antenna breakage detection method applicable to a receive-only branch regardless of the type of antenna used. .

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the first aspect of the present invention.

FIG. 2 is a diagram illustrating the operation of FIG. 1, where (a) is the case where the antenna 4 is damaged and (b) is the case where the antennas 3 and 4 are damaged.

FIG. 3 is a configuration diagram of the first and second embodiments of the present invention.

FIG. 4 is a main part configuration diagram of a reception level difference detection unit in FIG.

FIG. 5 is a configuration diagram of the third and fourth embodiments of the present invention.

FIG. 6 is a main part configuration diagram of a branch selection number integration circuit in FIG.

[Explanation of symbols]

 5 Demodulator 6 Transmitter 7 Branch selection number integration circuit 51 Demodulator 52 Reception level difference detection unit 61 Transmission circuit 62 Circulator 64 Comparator 71 Branch 3 selection number integration part 72 Branch 4 selection number integration part 73, 74 Comparator 75 OR Gate 521 Maximum reception level extraction circuit 522 to 524 Averaging part 525, 526 Subtraction part 527 First comparator 528 Second comparator 529 OR gate

Claims (6)

[Claims] 1. A radio system configured to receive radio waves by a space diversity receiving method using a plurality of antennas and transmit a radio wave by also using a predetermined number of antennas among the plurality of antennas for transmission. , Of the reception levels of the signals input via each antenna,
A value obtained by averaging the maximum reception level and reception levels other than the maximum reception level at regular intervals to obtain a time average, and subtracting the time average of the reception levels other than the maximum reception level from the time average of the maximum reception level. A method for detecting a fault in a radio system, wherein the fault is detected as a fault in the radio system when the value is equal to or more than a preset threshold. 2. The wireless system failure according to claim 1, wherein when all the antennas are damaged, the transmitting / receiving antenna is detected as a failure of the wireless system when the reflected wave is a predetermined amount or more. Detection method. 3. The radio system according to claim 1, wherein among reception levels of signals input via each antenna,
A radio characterized by integrating the number of selections for each antenna selected as the maximum reception level for a certain period of time, and detecting the number of selections for each antenna as a fault of the wireless system when the number of selections is less than a preset threshold value. System failure detection method. 4. The fault of the radio system according to claim 3, wherein when all the antennas are damaged, the antenna for both transmission and reception is detected as a fault of the radio system when the reflected wave exceeds a predetermined amount. Detection method. 5. The radio system according to claim 1, wherein among reception levels of signals input via each antenna,
A first maximum reception level extracting means for extracting a maximum reception level; and the extracted maximum reception level and reception levels other than the maximum reception level are averaged at regular intervals to obtain the maximum reception level and the maximum reception level. Averaging means for respectively obtaining the time average of reception levels other than the above is provided, and when the value obtained by subtracting the time average of the reception levels other than the maximum reception level from the time average of the maximum reception level is greater than or equal to a preset threshold value. A wireless system failure detection device having a configuration for detecting a failure in a wireless system. 6. The radio system according to claim 1, wherein among reception levels of signals input via each antenna,
Second maximum reception level extraction means for transmitting the antenna when the maximum reception level is extracted as a selection result, and an antenna-specific selection number accumulating portion for accumulating the number of selections for each antenna using the input selection result are provided. A radio system failure detection device characterized in that it is configured to detect a failure of the radio system when the integrated selection count for each antenna output by the selection count integration means for each antenna is equal to or less than a preset threshold value.