JPH02268024A - Active and standby reception circuit - Google Patents

Abstract

PURPOSE:To prevent loss due to signal branching by varying the coupling quantity between active and standby receivers with the control of a bias current of a PIN diode so as to branch the signal. CONSTITUTION:When an active receiver 1 is normal and a changeover circuit 4 at the output side is thrown to the position of the active side, no bias current is supplied to a PIN diode 6, the high respectively resistance of which is kept high, thereby minimizing the loss to the receiver 1. On the other hand, a constant bias current is supplied to a PIN diode 7 to keep signal leakage of a prescribed quantity thereby ensuring the operation monitor of the receiver 2 itself for the standby purpose. Then a monitor signal of the receiver 1 is used to allow a control circuit 5 to operate the changeover circuit 4 thereby selecting the receiver 2. In such a case, the bias current of the opposite condition to above is supplied to the input diodes 6, 7 to minimize the insertion loss of the receiver 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a receiving circuit that performs switching between active and standby, and particularly relates to a receiving circuit that reduces loss in the branch circuit portion.

[Conventional technology]

Conventionally, a signal switching circuit in this type of receiving circuit uses a hybrid branching method.

For example, as shown in FIG. 2, a hybrid 8 is provided on the input side of the active receiving device 1 and the backup receiving device 2, and a switching circuit 4 is provided on the output side. The input signal is then branched by the hybrid 8 and input to the active receiving device 1 and the backup receiving device 2. The switching circuit 4 on the output side is switched by a control circuit 9 operated by a monitor signal from each of the working and standby receiving devices 1.2, so that if one device (working side) fails, the other device ( (backup side) is selected to ensure reception.

[Problem to be solved by the invention]

In the conventional receiving circuit described above, the hybrid 8 is used to branch the input signal, so this hybrid has a branching loss of at least 3 dB or more, which is a major cause of performance deterioration in the system. Therefore, in the case of a receiving circuit having a backup receiving device, there is a problem in that the input to the receiving device is lowered by the loss caused by the hybrid, in this case by 3 dB or more, compared to a receiving circuit without a backup receiving device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a working protection receiving circuit that prevents losses due to signal branching.

[Means to solve the problem]

The working backup receiving circuit of the present invention includes working and backup receiving devices, a branch circuit provided on the input side of each of these receiving devices,
It includes a switching circuit provided on the output side and a control circuit that controls switching operations by the branch circuit and the switching circuit based on signals from each of the receiving devices, and the branch circuit has a PIN diode corresponding to each receiving device. The control circuit is connected to these PI
The configuration is such that the amount of coupling with each receiving device can be changed by controlling the bias current of the N diode.

[Effect]

In the above-described configuration, signal branching is performed by varying the amount of coupling with each of the working and standby receiving devices by controlling the bias current of the PIN diode, thereby eliminating the need for hybrid branching and suppressing loss due to signal branching.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention. In the figure, a branch circuit 3 is provided on the input side of the active receiving device 1 and the backup receiving device 2, and a switching circuit 4 is provided on the output side.

This branch circuit 3 is composed of PIN diodes 6.7 provided corresponding to each of the working and standby receiving bags W1 and 2, and a plurality of resistors and capacitors. Furthermore, the switching circuit 4 uses a circuit having the same switch configuration as the conventional one. The branch circuit 3 and the switching circuit 4 are controlled by a control circuit 5 operated by each monitor signal of the active receiving device 1 and the backup receiving device 2.

The control circuit 5 controls the branch circuit 3 by controlling the DC bias current of the PMN diode 6.7 in the branch circuit 3 to change the amount of coupling with the working and standby receiving devices 1.2.・It works like a sea urchin.

In this configuration, the input signal is branched by the branch circuit 3 to the active receiving device 1 and the backup receiving device 2.

At this time, the control circuit 5 operates as follows.

First, consider a state in which the working receiver 1 is normal and the output side switching circuit 4 selects the working side. At this time, no bias current is passed through the PIN diode 6, and the high frequency resistance of the PIN diode 6 is made high to minimize the loss to the working receiver side. On the other hand, a constant bias current is caused to flow through the PIN diode 7, and a constant amount, for example, 1
A signal leakage of about 0 dB is maintained to ensure that the standby receiving device 2 can monitor its own operation.

Here, if the current receiving bag W1 breaks down, 1. The control circuit 5 operates the switching circuit 4 based on the monitor signal of the active receiving device 1, and selects the backup receiving device 2.

At this time, the insertion loss of the backup receiving device 2 can be minimized by passing bias currents under conditions opposite to those described above to the PIN diodes 6 and 7 inside the branch circuit 3 on the input side.

Note that the maximum attenuation amount of the PIN diode 6.7 may be about 10 dB as described above, and as in the above embodiment, the maximum attenuation amount of the PIN diode 6.
This can be easily realized with a single stage configuration of diodes.

Furthermore, if the control speed of the branch circuit 3 is made slower than the follow-up speed of the AGC of the receiving device, errors will not occur in the signal when switching the branch circuit 3 even in PCM transmission.

〔Effect of the invention〕

As explained above, the present invention provides a PfN diode in a branch circuit that branches an input signal to each active and backup receiving device, and controls the bias current of these PIN diodes to change the amount of coupling with each receiving device. Since signal branching is performed using a hybrid system, there is an effect that branching by a hybrid is not required and loss due to signal branching can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional receiving circuit for active use and protection.

Claims (1)

[Claims] 1. Each of the working and backup receiving devices, a branch circuit provided on the input side of each of these receiving devices, a switching circuit provided on the output side, and signal switching by the branch circuit and switching circuit based on the signals of each of the receiving devices. and a control circuit for controlling the operation, the branch circuit has PIN diodes corresponding to each receiving device, and the control circuit controls the bias current of these PIN diodes to control the amount of coupling with each receiving device. A working standby receiving circuit characterized in that it is configured to be changeable.