JPS61265932A - Space diversity system - Google Patents

Abstract

PURPOSE:To use effectively the frequency and to prevent interference by arranging a sub antenna of a transmission station and a sub antenna of a reception station to a low frequency transmission line, connecting respectively a receiver to a main antenna of the reception station and the sub antenna and comparing reception outputs of each receiver so as to select a signal with an excellent characteristic as a reception as a reception signal thereby coping with fading. CONSTITUTION:The sub antennas 103, 305 are arranged oppositely to a low frequency transmission line, no sight is attained by a normal transmission line and no communication is executed by the sub antennas 105, 305. If fading takes place, a transmission signal having frequencies f1, f2 sent from active lines 111, 113 is sent to the main antenna 303 of the 2nd station of the sub antenna 305 via the main antenna 103 and the signal might or might not be received by the main antenna 303 or the sub antenna 305 due to the fading. A signal with better S/N is selected from the reception of the main antenna 303 and the sub antenna 305 by selectors 345, 347 and sent to active routes 353, 355 via changeover devices 349, 351. Thus, even when little fading takes place, the communication is conducted properly.

Description

[Detailed description of the invention] [Technical field of invention] This invention relates to a space diversity system.

[Technical Background of the Invention] Conventionally, there are the following space diversity systems in route protection switching type line-of-sight microwave communication lines.

In the first method, as shown in FIG. 3, main antennas 103, 303 are provided at transmitting station A and receiving station B, and sub-antennas 105, 305 are provided on the low-frequency propagation path.
303 uses, for example, three channel frequencies f, f, f3, and the sub antenna 105 uses a channel frequency f4.305 that is different from the aforementioned frequencies. f5. f6 is used to communicate between transmitting station A and receiving station B.

In the figure, T1. T2. T3. T1', T2'.

T' represents a transmitter, R, R2, R3°R', R'
, R3' represent the receiver.

At receiving station B, the combiner 5.7.9 connects each receiver R1 to
, R1'receiver R, and R2'receiver R3°R3' are combined and used as a received signal.

As a second method, as shown in FIG.
Sub-antennas 105, 305 so that the polarization planes of 5 are orthogonal to each other.
is provided, and the switch 11 is switched to select either the reception output of the reception IR or R4 as the reception signal. Similarly, the switches 13 and 15 are switched to select one of the reception outputs of reception IR, R and reception outputs 11R, R6 and use it as a reception signal.

In either method, during normal operation, the main antenna 103.
Communication is performed via antenna 303, and when deep duct fading occurs, transmission and reception by main antenna 103 and 303 are cut off, and communication is performed by secondary antennas 105 and 305 on the low-frequency propagation path.

[Problems with Background Art] However, in the two space diversity systems described above, transmission and reception are performed using the sub antenna only when deep fading occurs, and it is not possible to deal with fading other than this.

In addition, the former method requires double the number of radio channels than usual to prevent interference, and the latter method has the problem that the effect of orthogonal polarization deteriorates when fading occurs.

[Purpose of the Invention] Therefore, the purpose of the present invention is to provide a space diversity method that can deal with not only deep duct fading but also other types of fading, can effectively utilize frequencies, and does not cause interference, in order to solve the above-mentioned problems. It's about doing.

[Summary of the Invention] In order to achieve the above object, the present invention arranges the main antenna of the transmitting station and the main antenna of the receiving station on a normal propagation path, and connects the sub antenna of the transmitting station and the sub antenna of the receiving station to a low frequency band. A selector is provided that is placed in the propagation path, connects receivers to the main antenna and the auxiliary antenna of the receiving station, and compares the received outputs of the receivers and selects the signal with better characteristics as the received signal. It is characterized by

[Embodiments of the Invention] Examples of the present invention will be described in detail below based on the drawings.

FIG. 1 shows a first embodiment of the present invention, in which a first station 1
and the second station 3 through the main antenna 103.303 and the sub antenna 105.305.

In this embodiment, a case will be described in which the number of active wireless channels is two and the number of backup wireless channels is one.

The main antennas 103 and 303 face each other, ensuring visibility on the normal propagation path. The sub-antenna 105.305 is disposed opposite to the low-frequency propagation path, and there is no line of sight on the normal propagation path, so no communication is performed via the sub-antenna 10-5.305. However, line-of-sight from the sub-antenna 105 to the main antenna 303 or from the sub-antenna 305 to the main antenna 103 is ensured, or communication is performed in a state close to a steady state.

At the first station 1, the main antenna 103 and the sub antenna 105
are connected to duplexers 107 and 109, respectively.

The current routes 111 and 113 include this current route 111.
The multiplied signals of frequencies f and f2 via 113 are
Distributors 115 and 117 are provided to divide the
15.117 is connected to the working transmitter 119.121, and under normal conditions, the transmission signal of the working route 111.113 is sent to the second station 3 via the working transmitter 119.121, the duplexer 107, and the main antenna 103. Sent.

The backup route 123 is connected to a backup transmitter 129 via switchers 125 and 127, and the frequency fp of this backup route is
The transmission signal is transmitted to the second station 3 side via the backup transmitter 129, the duplexer 109, and the auxiliary antenna 105.

On the other hand, the receiving device that receives the signal sent from the second station has the following configuration. A receiver 131 is installed in the transmitter/receiver duplexer 107,
133.135 is connected, and reception 1 is sent to the duplexer 109.
1137.139.141 is connected.

Receivers 11131.141 receive signals at frequency f', and receivers 133, 139 receive signals at frequency f'.

The receivers 135 and 137 receive the signal at frequency f', and selectors 143 and 145 respectively receive the signal.
．． 147.

The selector 143 compares the output signals of the receivers 11131 and 141 and selects the signal with a better signal-to-noise ratio (SN ratio).

The selectors 145 and 147 also select signals from the receivers 133 and 139 and the receivers 135 and 137, whichever has a better SN ratio.

Selectors 145, 147 are connected to working routes 153, 155 via switches 149, 151, respectively.

The switching devices 149.151 connected to the selector 143 check the line status of the working route 153.155 and the backup route 157, and switch between the working route 153, the backup route 157, and the backup route 157, respectively.
This is used to switch between the working route 155 and the backup route 157.

The configuration of the second station 3 is exactly the same as the configuration of the first station 1, and the elements of the second station are number.

Next, the operation when communicating from the first station to the second station will be explained.

During normal operation, the transmission signals of frequencies f and f2 from the working route 111.113 are transmitted via the distributor 115.117, the working transmitter 1tll19.121, the duplexer 107, and the main antenna 103 to the main antenna 303 or sub antenna 305 of the second station. reach.

The signal reaching the main antenna 303 is received by the receivers 333, 335 via the duplexer 307, and is received by the selectors 345, 3.
47.

Further, the signal reaching the sub antenna 305 is received by the receiver 339.337 via the transmitter/receiver duplexer 309, and is sent to the selector 345.3.
47.

The selectors 345 and 347 receive @333, respectively.

The signals received by 339 and the receiver 335.337 are compared, and the signal with a better S/N ratio is selected and the signal is sent to the switch 349.3.
51 to the current routes 353 to 355.

Next, when fading occurs, the working line 111.
The transmission signals of frequencies f1 and f2 sent from 113 are sent to the main antenna 303 or the sub antenna 305 of the second station via the main antenna 103 as described above, but due to fading, It may happen that the signal is received or not received by the sub antenna 305.

The received outputs of the main antenna 303 and the sub antenna 305 are selected by selectors 345 and 347 to select the signal with a better S/N ratio, and then sent to the active route 353 via switchers 349 and 351.
, 355.

In this way, even if slight fading occurs, appropriate communication can be performed.

If even deeper duct fading occurs, the main antenna 103 is connected to the main antenna 303 and the sub antenna 30.
5 is blocked out.

At this time, it becomes possible to see the auxiliary antenna 105 and the auxiliary antenna 305 on the low-frequency propagation path.

Therefore, the signal of frequency fO sent from the backup route 123 passes through the switching devices 125 and 127, and then goes to the backup transmitter 129,
It is transmitted from the duplexer 109 and the auxiliary antenna 105 to the auxiliary antenna 305 of the second station 3.

The signal of frequency f that reaches the sub antenna 305 is received by the receiver 341 via the duplexer 309 and sent to the selector 343.
It is sent to the backup route 357 via.

When the receiving side detects this f, the backup route 323,
Switcher 325, 327 transmitter 329, duplexer 309
, sends a switching signal toward the first station 1 via the fW1 antenna 305.

In the first station 1, this switching signal is received by the receiver 141 via the sub antenna 105 and the duplexer 109, and is received by the selector 14.
3 to the backup route 157, and when the first station 1 detects this switching signal, the switch 125, 127 selects the line with the higher priority among the working routes 111, 113. For example, if the current route 111 has a higher priority, the switching device 125 blocks both the frequency f2 and fp signals, and the switching device 127 blocks the frequency f2 and fp signals.
1 signal is sent to the transmitter 129 and transmitted from the duplexer 109 and the auxiliary antenna 105 to the second station 3.

At the second station 3, the signal of this frequency f is transmitted to the sub antenna 305.
, is received by the transmitter/receiver duplexer 309 wosuke L/reception 1!1339 and is supplied to the switch 349 via the selector 345. At this time, the switch 349 switches from the backup route 357 to the working route 353, so the signal of frequency f1 is sent to the working line 353.

As described above, appropriate communication is performed even during mild fading other than deep duct fading.

FIG. 2 shows another embodiment of the present invention, in which the first station 1 and the second station 3 are provided with a switch 159,359 and a transmitter 111161,361.

During normal operation and when light fading occurs, the switch 159 connects the switch 127 and the transmitter 161, so that the transmitters 119, 121, and 161 select frequencies f and f.
, fO signals are transmitted from the main antenna 103 to the 283rd main antenna 303 and the auxiliary antenna 305.

These signals f , f , fp are sent to the receiver 333°3
39, Reception 1335.337, Reception l11331°34
1, and the selectors 345, 347, 343 select S.
A signal with a good N ratio is selected and the current route is 353.355.
and is sent to the backup route 357.

When deep duct fading occurs, the main antenna 303
And the sub antenna 305 cannot receive radio waves, and the frequency f
The switching signal of p' is sent to the switch 359, transmission 11329, II
The signal is sent to the sub antenna 105 of the first station 1 via the antenna 305.

In the transmitting station 1, this switching signal is sent to the backup route 157 via the duplexer 109, the receiver 141, and the selector 143, and this switching signal is detected.

When the switching signal is detected, the switching device 159 switches, and the first
Similarly to the embodiment, a signal with a higher priority among the signals of frequency f1 or f2 is sent to the second station 3 via the transmitter 129 and the auxiliary antenna 105, and is received within the second station 3.

In the two embodiments described above, the number of active wireless channels is 2.
Although the case where the number of spare wireless channels is 1 is taken as an example, the number of channels is not limited to this.

Further, the selector may compare the S/N ratio of the signals or may compare other characteristics.

[Effects of the Invention] As explained in detail above, the present invention provides a space diversity method that can deal with not only deep duct fading but also other types of aging, can effectively utilize frequencies, and does not cause interference. can do.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the invention, FIG. 2 is a block diagram of another embodiment, and FIGS. 3 and 4 are block diagrams of a conventional space diversity system. be. 1... 1st station, 3... 2nd station, 103.303...
・Main antenna, 105.305... Sub antenna, 13
1.133,135,137,139,141...Receiver, 331.333,335,337,339.341...
・Receiver, 1'43,145,147,343,345.347・
...Selector. Figure 3 Figure 4

Claims (1)

[Claims] The main antenna of the transmitting station and the main antenna of the receiving station are placed on the normal propagation path, the sub antenna of the transmitting station and the sub antenna of the receiving station are placed on the low frequency propagation path, and the main antenna and the sub antenna of the receiving station are placed on the normal propagation path. A space diversity system characterized in that receivers are connected to each other, and a selector is provided for comparing the reception outputs of the respective receivers and selecting a signal with better characteristics as a reception signal.