JPH07321714A - Bipolar signal changeover circuit - Google Patents

Abstract

PURPOSE:To obtain a bipolar signal changeover circuit in which the number of unipolar/bipolar converters is reduced, no switch is required to simplify the configuration and signal interruption is prevented. CONSTITUTION:The changeover circuit is provided with tri-state buffers B1-B4 provided in respective paths of two unipolar signals being positive and negative signals for spare and active states, a unipolar/bipolar converter 7 converting a unipolar signal outputted from the tri-state buffers into a bipolar signal, and a control signal generating means 8 selecting outputs of the tri-state buffers B1-B4 as an active or a spare state and giving the result to the unipolar/bipolar converter 7, the selected tri-state buffer is set to be an active buffer, its output is given to the unipolar/bipolar converter 7 and the tri-state buffers not selected are set to a high impedance state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bipolar signal switching circuit, and more particularly to a switching circuit for a receiving side bipolar signal output of a radio device which constitutes a working / standby system.

[0002]

2. Description of the Related Art Generally, a receiving side of a wireless device is configured to have a working and a standby redundant configuration in order to cope with a failure of a communication path and to select a side having a good communication state for communication.
In particular, a wireless device that converts a bipolar signal into positive and negative unipolar signals on the transmitting side for wireless transmission, and then receives these unipolar signals on the receiving side and then converts them to bipolar signals for communication. Then, as shown in FIG. 5, the working digital signal and the backup digital signal output from the demodulating unit of the receiving apparatus are input from the input terminals IN100 and IN200, and the additional code in the wireless section is received by the receiving code processing units 101 and 201. After the removal, each data signal is input to the unipolar / bipolar converters 102 and 202 and converted into a bipolar signal in each. And working,
One of the two spare bipolar signals is selected by the switch 300 and output to the output terminal OUT300.
For example, "Digital Microwave Communications" supervised by Moruji Kuwahara,
See Planning Center Co., Ltd., issued May 25, 1984, page 313.

As a circuit configuration of the unipolar / bipolar converter and the switch in this case, the one shown in FIG. 6 has been generally proposed. In the figure, the input terminal IN1
Two positive-polarity signals and negative-polarity signals on the working side are input from 1, IN12, passed through buffers B11, B12, and then converted into a bipolar signal by a unipolar / bipolar converter 10. The converted bipolar signal is input to one terminal of the switch 30. Similarly, on the spare side, the positive side signal and the negative side signal on the spare side are input from the input terminals IN13 and IN14, respectively, and are converted into bipolar signals by the unipolar / bipolar converter 20 via the buffers B13 and B14. The converted bipolar signal is input to the other terminal of the switch 30. Then, in the switch 30, the control terminal CON
Either the working bipolar signal or the spare bipolar signal is selected by the switching signal input to T10 and output to the output terminal OUT10.

[0004]

The conventional bipolar signal switching circuit as described above has a problem in that the unipolar / bipolar converters 10 and 20 are required for each of the working and the spares, which makes the structure complicated. Further, the switch 30 is required as a switch, and a mechanical switch such as a relay switch or an electrical switch such as an analog switch is used as this switch, but in any case, the configuration becomes complicated. There is a problem. In particular, when a mechanical switch is used as the switch, a momentary disconnection of the signal may occur when the output end is momentarily opened so that the output end is not connected to any input side during the switching operation.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bipolar signal switching circuit having a simplified structure by reducing the number of unipolar / bipolar converters. Another object of the present invention is to provide a bipolar signal changeover circuit which simplifies the structure by eliminating the need for a working / standby changeover switch. Furthermore, the present invention provides a bipolar signal switching circuit which eliminates the instantaneous interruption of signals at the time of switching.

[0006]

SUMMARY OF THE INVENTION A bipolar signal switching circuit according to the present invention is provided with two positive and negative signals for working and protection.
Means for selecting one unipolar signal between working and spare,
And a single unipolar / bipolar converter for converting the selected unipolar signal to a bipolar signal.

For example, according to the present invention, a three-state buffer provided on each path of two unipolar signals, that is, a positive electrode signal and a negative electrode signal for current and standby, and a unipolar signal output from these three-state buffers are bipolar. A unipolar / bipolar converter for converting into a signal; and means for generating a control signal for selecting the output of the three-state buffer between working and spare and inputting it to the unipolar / bipolar converter. There is.

Here, the means for generating the control signal outputs a control signal for bringing the selected 3-state buffer into an active state and the non-selected 3-state buffer into a high impedance state.

[0009]

Of the three-state buffers provided at the output ends of the working or spare unipolar signals, the selected three-state buffer is made active and its output is input to the unipolar / bipolar converter, and the unselected three-state buffer is selected. By setting the high impedance state, 1
It is possible to convert the selected unipolar signal into a bipolar signal with a single unipolar / bipolar converter and without requiring a switch for selection.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is an embodiment in which the present invention is applied to the receiving side of a wireless device, and here shows an example in which one working line and one protection line are used. On this receiving side, the reception signal received by the antenna 1 is separated into positive and negative unipolar signals of the working line 2 and the protection line 3 to perform predetermined reception signal processing, and the separated working signal. And selecting means 5 and 6 for switching and selecting each spare unipolar signal, and unipolar / bipolar converting means 7 for converting each of the selected working or spare positive and negative unipolar signals into a bipolar signal. The control signal generating means 8 monitors the reception state based on the bipolar signal and outputs a switching signal for switching between the working mode and the standby mode to the switching means.

FIG. 2 is a circuit diagram showing a specific configuration of the selecting means 5 and 6 and the unipolar / bipolar converting means 7. Two unipolar signals of the positive line signal and the negative line signal of the working line 2 are input to the input terminals IN1 and IN2. A 3-state buffer B is provided at each of the input terminals IN1 and IN2.
1, B2 are connected, and the outputs of these three-state buffers B1, B2 are input to the negative input terminal (−) and the positive input terminal (+) of the unipolar / bipolar converter 7, respectively.

Further, two unipolar signals of the positive line signal and the negative line signal of the protection line 3 are input to the input terminals IN3 and IN4. Three-state buffers B3 and B4 are connected to the respective input terminals IN3 and IN4, and the outputs of these three-state buffers B3 and B4 are the negative input terminal (-) and the positive input terminal (-) of the unipolar / bipolar converter 7. +)
Are input respectively.

That is, in this configuration, on the working side and the spare side, the outputs of the three-state buffers B1 and B3 for each positive polarity signal are wired-OR connected, and similarly, the outputs of the three-state buffers B2 and B4 for each negative polarity signal are generated. Wired OR to each other
They are connected to the negative input terminal (-) and the positive input terminal (+) of one unipolar / bipolar converter 7, respectively.

The outputs of the three-state buffers B1 to B4 are set to a high impedance state according to the states of the control signals input to the control terminals CONT1 to CONT4, or "L" or "H" depending on the input signals. Any of three different states. For example, FIG. 3 is a circuit diagram showing an example thereof, and here it is composed of a control signal side inverter circuit for inverting a control signal and an input signal side inverter circuit for inverting and outputting an input signal. In the figure, Q1 to Q9 are transistors, D1 and D2 are diodes, and R1 to R9 are resistors.

In this 3-state buffer, the control signal C
Is "L", it is in an active state, its output X becomes an inverted signal of the input signal A, and has an output level of "L" or "H". Further, when the control signal C is "H", the output X is in a high impedance state. Further, here, as shown in FIG. 2, the control terminals CON1 and CONT2 of the buffers B1 and B2 are put together, and similarly,
The control terminals CONT3 and CONT4 of B3 and B4 are collectively connected to the control signal generating means.

The control signal generating means 8 is for generating a signal for selecting the working or protection from the state of the received signal, and when selecting the working, each of the three-state buffers B1 and B2 on the working side. Control terminals CONT1, C
An "L" level signal is output to ONT2, and control terminals CONT3, CO of the three-state buffers B3, B4 on the spare side are output.
An "H" level signal is output to NT4. On the contrary, when the spare is selected, the three-state buffers B1, B on the working side are selected.
An "H" level signal is output to 2 and an "L" level signal is output to the spare 3-state buffers B3 and B4.

Therefore, in the bipolar signal conversion circuit having this structure, the control signal generating means 8 generates a control signal for selecting the active or standby mode on the basis of the reception state, and each of the four 3-state buffers B1 to B4. Output to. For example, when the active side is selected, a control signal of "L" level is output to the active 3-state buffers B1 and B2, and the standby 3-state buffers B3 and B4.
A control signal of "H" level is output to the. Therefore, on the working side, the three-state buffers B1 and B2 become active, the unipolar signals of the positive polarity signal and the negative polarity signal are inverted, and the unipolar / bipolar converter 7 is inverted.
Are input to the negative input terminal and the positive input terminal of the, and are converted into a bipolar signal here.

At this time, since the outputs of the respective state buffers B3 and B4 are in a high impedance state on the spare side, the spare side is in a state of being cut off from the unipolar / bipolar converter 7. Therefore, the operation of converting the bipolar signal in the unipolar / bipolar converter 7 is not affected by the unipolar signal on the spare side.

On the contrary, when the spare side is selected, the "H" level control signal is output to the active side 3-state buffers B1 and B2, and the spare side 3-state buffer B is output.
An "L" level control signal is output to B3 and B4.
Therefore, on the working side, each of the three-state buffers B1 and B2 is
Becomes a high-impedance state, each of the three-state buffers B3 and B4 becomes active on the spare side, and the positive-side signal and the negative-side unipolar signal on the standby side are respectively inverted and the negative-side input terminal and the positive-side input of the unipolar-bipolar converter 7 are inverted. It is input to the end and is converted into a bipolar signal here. At this time, since the working side is cut off from the unipolar / bipolar converter 7, the working side unipolar signal does not affect the unipolar / bipolar converter 7.

As a result, the unipolar / bipolar converter 7 selects and inputs only one of the working signal and the spare signal, and converts it into a bipolar signal and outputs it from the output terminal OUT. Become. Therefore, only one of the working and the spare unipolar signals selected by the three-state buffers B1 to B4 is selected and input to the unipolar / bipolar converter 7, so that one unipolar / bipolar converter 7 is used. In this way, both current and standby reception are possible and the configuration can be simplified.

Further, when selecting the working and the spare, no switch means is required, and no mechanical switch is required in particular, so that the structure can be simplified. Further, when compared with an electric switch such as an analog switch which has been used conventionally, there is no significant difference in terms of simplifying the circuit configuration, but in this embodiment, switching of the output state by a 3-state buffer is performed. Because it only does
It is possible to prevent the loss of the signal without the instantaneous interruption of the signal occurring in the switch.

Here, the above-mentioned embodiment shows an example of the present invention, and for example, the 3-state buffer may have a circuit structure other than the inverter structure of the above-mentioned embodiment. For example, as shown in FIG. 4, 3-state buffers B1 'to B1 in which level inversion does not occur between input and output signals.
4 ', in which case the positive and negative signals of each unipolar signal are input to the positive and negative input terminals (+) and (-) of the unipolar / bipolar converter 7, respectively. Become. Further, in the above-mentioned embodiment, the structure of one working and one spare is illustrated, but the present invention can be applied in the same manner even in the case of a plurality of working and spare structures.

[0023]

As described above, according to the present invention, two unipolar signals, that is, a positive electrode signal and a negative electrode signal for the working and protection are selected for working and protection, and the selected unipolar signal is used in the unipolar / bipolar converter. Since it is converted into a bipolar signal, a plurality of unipolar signals can be selected and converted into a bipolar signal by one unipolar / bipolar converter, and the configuration can be simplified.

According to the present invention, a three-state buffer provided on each path of two unipolar signals, that is, a positive electrode signal and a negative electrode signal for the working and protection, and a unipolar signal output from these three-state buffers are converted into bipolar signals. One unipolar bipolar signal converter to convert,
The control signal to be input to the three-state buffer is controlled by means for selecting the output of the three-state buffer as either active or spare and generating a control signal to be input to the unipolar / bipolar signal converter. By doing so, the selected working or spare unipolar signal can be converted by one unipolar / bipolar converter, and a switch is not required for selection, so that the structure can be simplified.

Further, since the selected 3-state buffer is activated by the control signal and the unselected 3-state buffer is set to the high impedance state, the unipolar signal can be selected. There is no interruption of signal.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an example of a receiver to which a bipolar signal switching circuit of the present invention is applied.

FIG. 2 is a block circuit diagram of a main part of a bipolar signal switching circuit of the present invention.

FIG. 3 is a circuit diagram showing an example of a 3-state buffer.

FIG. 4 is a block circuit diagram of a main part of a bipolar signal switching circuit according to another embodiment of the present invention.

FIG. 5 is a block configuration diagram of a part of a receiving device including a conventional bipolar signal switching circuit.

FIG. 6 is a circuit diagram of an example of a conventional bipolar signal switching circuit.

[Explanation of symbols]

 2 working line 3 protection line 4 receiving means 5, 6 selecting means 7 unipolar / bipolar signal converting means 8 control signal generating means B1 to B4 3 state buffer

Claims (4)

[Claims] 1. A bipolar signal switching circuit for selecting two unipolar signals of a positive electrode signal and a negative electrode signal of a working and a protection and outputting them as a working or a protection bipolar signal. A bipolar signal switching circuit comprising: a selecting means; and a single unipolar / bipolar converter for converting the selected unipolar signal into a bipolar signal. 2. A bipolar signal switching circuit for selecting two unipolar signals of a positive electrode signal for a working and a spare and a negative signal for outputting as a bipolar signal for a working or a spare, respectively. A 3-state buffer provided on each path of the negative and negative signals, a single unipolar / bipolar converter for converting the unipolar signal output from these 3-state buffers into a bipolar signal, and an output of the 3-state buffer And a means for generating a control signal to be input to the unipolar / bipolar converter by selecting either the active or the standby mode. 3. The bipolar signal switching circuit according to claim 2, wherein the means for generating a control signal outputs a control signal for activating a selected three-state buffer and setting a non-selected three-state buffer in a high impedance state. 4. The bipolar signal switching circuit according to claim 3, wherein the means for generating the control signal outputs the control signal according to a reception state on the receiving side of the wireless device.