JPH04351005A - Radio repeater - Google Patents

Abstract

PURPOSE:To identify it system abnormal oscillation when at least one reception input is excessive resulting in saturating a transmission output and suppressing the amplification factor and to immediately restore a relay amplification gain when the excess input of the said one wave is released in the ratio repeater receiving a radio wave from a mobile radio equipment, relaying and amplifying the received radio wave and re-transmitting the result. CONSTITUTION:A variable attenuator 12 varying the relay amplification gain is provided in front of a relay amplifier, a coupler 14 provided to a transmission output terminal detects a transmission output, the detection level is detected by a level detector 15 driving the level in two steps and the result is given to a control section 16. Thus, whether an excess input abnormality or abnormal oscillation is identified, and when the abnormality of the excess input is released, the attenuation of the variable attenuator 12 is immediately restored to the initial value.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a radio relay device that amplifies signals of multiple radio frequencies received by a receiving antenna and retransmits the same radio frequency as the received signal from a transmitting antenna. The present invention relates to a wireless relay device having a function of identifying the cause of an abnormality.

0002

[Prior Art] In mobile communications such as car phones, even in service areas, there are areas with weak electric fields where radio wave propagation loss is large and communication is difficult due to the influence of surrounding topography and buildings. be. A wireless relay device is available as a means of relieving such weak electric field areas.

For example, there are a two-way wireless relay device as shown in FIG. 7 and a one-way wireless relay device as shown in FIG. 6, but the present invention can be applied to both bidirectional and unidirectional devices. Therefore, the following explanation will be made regarding a unidirectional wireless relay device.

FIG. 6 is a block diagram showing the configuration of a conventional radio relay device, which is composed of a receiving antenna 1, a transmitting antenna 2, an amplifier 3 (gain G), a coupler 4, a level detector 5, and a control section 6. ing. Such a relay device has the following problems. (1) The transmitted wave sent out after being relayed and amplified wraps around to receiving antenna 1, and is transferred from transmitting antenna 2 to receiving antenna 1.
The propagation loss (Ld
If B) is smaller than the gain of the repeater (the gain from the receiving antenna terminal to the transmitting antenna terminal), the system becomes unstable and oscillation occurs. When oscillation occurs, the relay device transmits at saturated output, causing interference to the system. (2) If the mobile station gets very close to the receiving antenna of the relay device, the input to the relay device becomes excessive (input abnormality) and the output of the relay device becomes saturated. A relay device used in such a time multi-frequency system transmits only one wave,
Other radio signals are masked and become unusable.

[0005] Normally, the station placement design is done with sufficient consideration to avoid the problems (1) and (2) above, but (1)
In this case, even if the propagation loss between the transmitting and receiving antennas 7 is sufficient when the repeater is installed, factors that reduce the propagation loss between the transmitting and receiving antennas may occur due to subsequent changes in the surrounding conditions (such as buildings with reflective objects). Sometimes. Also, in the case of (2), problems may occur if the device is used in a place where it is not supposed to be used due to the design, or if there is an installation error.

[0006] Abnormalities in either of the above cases (1) and (2) result in a saturated output and cause disturbance to the system. In order to avoid this interference, the transmitting output is monitored by the coupler 4, and the transmitting output level is detected by the level detector 5.
When the signal is set to 1), the gain of the amplifier 3 is lowered by a control signal from the controller 6, thereby lowering the transmission output.

[0007]

However, with such conventional control, it is not possible to distinguish whether the system is in an oscillation state and the output is saturated, or whether the output is saturated due to excessive input. Therefore, if the output is abnormal, the repeater assumes that oscillation is the cause and reduces the gain to provide a low-gain relay service, but if the cause is excessive input, the gain returns to normal as soon as the input abnormality is removed. Since it cannot be restored, the gain will be used with reduced gain for a long period of time, resulting in deterioration of communication service.

[0008] In such a conventional device, in the case of excessive input (
The same control as in the case of abnormal oscillation (input abnormality) is carried out, and even if the excessive input state is canceled, the repeater does not recognize it, so it is difficult to restore the normal gain state. In the case of an oscillation state, it is unavoidable that it takes time to recover and the service area decreases, but in the case of excessive input, it is necessary to immediately return to the normal gain state as soon as the input abnormality is removed. SUMMARY OF THE INVENTION An object of the present invention is to provide a wireless relay device that can identify either an output abnormality due to excessive input or an output abnormality due to oscillation, and can restore the relay gain at the same time when the excessive input is canceled. .

[0009]

[Means for Solving the Problems] A radio relay device of the present invention amplifies a radio signal received via a receiving antenna with an amplifier and retransmits it from a transmitting antenna, in which a certain amount of attenuation is sequentially increased. a variable attenuator provided on the input side of the amplifier in order to change the gain of the amplifier; a coupler that detects a voltage proportional to the transmission output level from the transmission antenna; and a rectification of the detected voltage from the coupler. and a level detector that compares the transmission output level with a plurality of predetermined comparison voltage levels to specify the transmission output level and outputs a level detection output when the comparison voltage is exceeded, and when the transmission output level is in a saturated state. As the attenuation amount of the variable attenuator is changed, it is determined whether the saturation state is due to system oscillation or the input to the amplifier is excessive, based on the change in the level detection output of the level detector in multiple stages according to the change in the attenuation amount. and a control unit that performs control such that the amount of attenuation of the variable attenuator returns to an initial value as soon as the excessive input state is canceled when the excessive input state is caused. .

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an example of the configuration of a wireless relay device according to the present invention. The difference from the conventional example shown in FIG. 6 is that a variable attenuator 12 is inserted before the amplifier 3, and the level detector 5 is replaced as a detailed example thereof is shown in FIG. Figure 2
, 151 to 15n are n level detectors, and E1 to En indicate their comparison voltages. 150 is a rectifier.

Next, FIG. 2 shows details of the level detector 15.
The following circuit will be explained. Level detector 151-15
The n comparison voltages E1 to En are voltages for setting the transmission output level. A total of n level detectors can detect the transmission output that is attenuated from the saturated output of the amplifier 3 to n·xdB in xdB steps. In the following expression, when the transmission output exceeds the threshold value in the level detector 15, it is "detected", and when it does not, it is "not detected".

Under normal usage conditions (attenuation of the variable attenuator 12 is 0 dB, normal input, no oscillation), the comparison voltage E1 of the level detector 151 is not exceeded and the output of the level detector 151 cannot be judged. No detection (no output abnormality). A variable attenuator 12 is installed before such a linear amplifier 3.
When inserting, the attenuation amount of attenuator 12 becomes xdB, 2xdB
...(n-1)xdB, if the input is normal, the output of the level detector 15 ■■...n is determined to be no detection (no output abnormality). These determinations are made by the control unit 16.

FIGS. 3 and 4 show second and third embodiments of the level detector 15 used in the present invention. In order to reduce hardware in consideration of economic efficiency, the second embodiment of FIG. The comparison voltage E1 is set by the CPU 155 using the level detector 151 as one.
~En Outputs digital information corresponding to D/A
The configuration is such that a converter 156 converts them into analog signals and supplies E1 to En to a level detector 151 to obtain level detection outputs 1 to n. In the third embodiment shown in FIG. 4, the output of the rectifier 150, which is proportional to the transmission output level, is digitally converted by the A/D converter 157 and processed by the CPU 158 to obtain a desired detection output.

[I] First, discrimination between an input abnormality (excessive input) and an oscillation state will be explained with reference to FIGS. 1, 2, and 5. FIG. 5 is an explanatory diagram showing the state of abnormality determination control. The vertical axis in FIG. 5 represents the transmission output level of the wireless relay device, and the horizontal axis represents the time axis. That is, it shows the progress of increasing the amount of attenuation of the attenuator over time and identifying the cause of the output abnormality. The level detection output ■ on the vertical axis is the comparison voltage E1 of the level detection output ■ of the level detector 151 in FIG.
The corresponding transmission output level is shown. The same applies to the level detection outputs ■...n. Under normal usage conditions (the attenuation of the variable attenuator 12 is 0 dB, normal input, and no oscillation), the transmission output level is between detection levels ■ and ■, that is, region 2.
, and never exceeds the dotted line in FIG. Although it is unclear whether the initial state is an input abnormality or an abnormality due to oscillation, it is assumed that the level detector 151 is "detected", that is, the state is in region 1. (1) At this time, the attenuation amount of the variable attenuator 12 is xdB(
When changed to the initial state (0 dB), a, b,
It will be in one of the states c. (Amplifier gain (G-x)
dB)

[Table 1] However, ○ indicates detection, and × indicates no detection.

[0015] If the original cause of the abnormal output state is excessive input, the transmission output level when attenuated by x dB will be in region 2 or higher (region 2 or region 1). That is, the state becomes either b or a. If oscillation is the cause, the oscillation will stop and the normal state will be restored, resulting in the transmission output level being in region 3 corresponding to the amplifier gain (G-x) dB (does not exceed the dotted line in Figure 5), that is, state c? , or the oscillation does not stop and remains in the saturated output state, and the level of region 1 continues, that is, state a
Either it becomes. Therefore, the cause of the original abnormal output state is oscillation in state c, abnormal input in state b, and either oscillation or abnormal input in state a.

(2) Next, in case of state a in (1),
Since the cause of the output abnormality is unknown, if the attenuation amount of the attenuator 12 is further increased by x dB to a total of 2 x dB, then the states a', b1', b2', and c' as shown in Table 2 are considered.

[Table 2] Similarly to (1), if the cause of the output abnormality is excessive input, the transmission output level when attenuated by 2xdB is
This is the above (area 3, area 2, or area 1). That is, the state becomes b2', b1' or a'. If the cause is oscillation, either the oscillation is stopped and the state becomes region 4, that is, state c', or the oscillation does not stop and remains in region 1, that is, state a'. The value indicated by the dotted line in FIG. 5 indicates that if the input is normal and there is no oscillation, no more than this value will be detected. (3) If the judgment result is unknown in this way,
The cause can be determined by increasing the amount of attenuation of the attenuator 12 up to (n-1)xdB in dB steps.

[II] Next, a description will be given of control for restoring the gain of the relay device when the cause of the abnormality is determined to be excessive input and the excessive input is subsequently released. Since the input is large, the attenuation amount of the attenuator 12 is set to xdB as explained in [I].
b(b,b',b1',...bn-
If the condition 1) occurs, it can be determined that there is an input error. Thereafter, when the input abnormality disappears, the attenuation amount of the attenuator 12 is reduced by x dB until it returns to the initial gain of the relay device or region 2 (level detection output (2) is not detected, level detection output (2) is detected). In this way, the gain of the relay device can be restored instantaneously.

[0018]

[Effects of the Invention] As explained in detail above, by implementing the present invention, when the cause of an output abnormality is determined and it is determined that the output abnormality is due to excessive input, the output abnormality can be immediately detected when the input returns to normal. Since the gain of the relay device can be returned to its initial value, it has the great effect of suppressing the deterioration of service in a short period of time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a first embodiment of the main part of the present invention.

FIG. 3 is a circuit diagram showing a second embodiment of the main part of the present invention.

FIG. 4 is a circuit diagram showing a third embodiment of the main part of the present invention.

FIG. 5 is an explanatory diagram of the operation of the present invention.

FIG. 6 is a block diagram of a conventional device.

FIG. 7 is a block diagram of a conventional device.

[Explanation of symbols]

1 Antenna 2 Antenna 3 Amplifier 4 Combiner 5 Level detector 6 Control section 7 Detour route 8　Shared device 9　Shared device 12 Variable attenuator 14 Combiner 15 Level detector 16 Control section 30 Downstream amplifier 40 Upstream amplifier 150 Rectifier 151 Level detector 152 Level detector 15n level detector 154 Processing circuit 155 CPU 156 D/A converter 157 A/D converter 158 CPU

Claims (1)

[Claims] 1. A radio relay device that amplifies a radio signal received via a receiving antenna with an amplifier and retransmits it from a transmitting antenna, in which the gain of the amplifier is changed by sequentially increasing a certain amount of attenuation. a variable attenuator provided on the input side; a coupler for detecting a voltage proportional to the transmission output level from the transmission antenna; A level detector that compares with a plurality of predetermined comparison voltage levels and outputs a level detection output when the comparison voltage exceeds the comparison voltage, and changes the amount of attenuation of the variable attenuator when the transmission output level is in a saturated state, Determining whether the saturation state is due to system oscillation or excessive input to the amplifier from changes in the level detection output of the level detector in multiple stages according to changes in the attenuation amount, and determining whether the saturation state is due to excessive input to the amplifier. and a control unit that performs control such that the amount of attenuation of the variable attenuator returns to an initial value as soon as the excessive input is released.