JPS60237731A - Switching device of if band circuit - Google Patents

Abstract

PURPOSE:To compensate amplitude characteristics and variation in signal level at the time of switching from an in-use circuit to a stand-by circuit and stabilize the switching by providing an IF band variable amplitude equalizer and a means which outputs a control signal corresponding to the level of a pilot signal to a stand-by circuit route. CONSTITUTION:An amplitude equalizer 5 for the IF band is inserted into the stand-by circuit of the IF band circuit switching device used for microwave communication for multiplex telephone signal transmission, and this equalizer 5 is controlled with the output of a control circuit 6. A stand-by circuit pilot signal and a pilot signals detected by a detector 2 for a noise and a detector 14 for an in-use pilot signal are inputted to the control circuit 6. Then, if one of detectors 11-13 for the pilot signal of the in-use circuit detects abnormality and the transmission-side switch of the other party station in driven to send the signal of the in-use circuit to the stand-by circuit, the detector 14 outputs the pilot signal. The quantity of equalization is varied with the output corresponding to variation in the level of the pilot signal to compensate base-band amplitude characteristics and variation in pilot signal level due to the switching between the circuits.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intermediate frequency (IF) band line switching device used in microwave communication for transmitting multiple telephone signals.

(Prior art) Conventionally, IF band line switching equipment used in microwave communication systems monitors the line pilot signal and noise level on the receiving side, and if any of these is detected to be abnormal. In this case, the switch on the transmitting side was operated through the line control equipment, the same signal was transmitted over the protection line, and the level of the pilot signal and noise was checked on the receiving side. If these levels are normal, the switch on the receiving end operates and the switching from the working line to the protection line is completed.

On the other hand, when transmitting television signals, there are more than 10 HOPs.
The reality is that there are many transmissions that extend over 100 days, and that there are many branches and additions from stations along the way. In microwave communication, the amplitude characteristics in the high frequency range of the baseband band deteriorates as the number of HOPs relayed increases (due to changes in characteristics due to propagation path conditions and addition of equipment), At the station, it is recommended to install an equalizer after the demodulator to compensate for the deterioration of the amplitude characteristics.
It was common.

FIG. 1 is a block diagram showing an example of a receiving section of a line switching device according to the prior art. In Figure 1, 11 to 14
are a detector for detecting the working line pilot and noise, 2 is a detector for detecting the protection line pilot and noise, 3 is a receiving end switch, and 4 is an FM oscillator for reinserting the pilot signal. .

When the line is switched from the working line to the protection line in the above configuration, the amplitude characteristics of the baseband band and the pilot signal level will fluctuate because the transmission route and equipment used will be different. There were drawbacks.

(Object of the Invention) The object of the present invention is to reduce the amplitude in the baseband band that occurs due to differences in transmission routes and differences in transmitting/receiving equipment when switching from a working line to a protection line in a microwave communication system. The above disadvantages are eliminated by reducing changes in characteristics, especially in high frequencies, and further stabilizing the level of the pilot signal that is used as a reference for line switching. It is an object of the present invention to provide an IP band line switching device configured to be able to correct the amplitude characteristics in the baseband band and the fluctuations in the No. 74071 level that occur.

(Structure of the Invention) The IF band line switching device according to the present invention has a working line and a protection line, and can switch between the two lines using a working protection changeover switch. instrument and multiple detectors.

This configuration includes a control circuit.

The IP band variable amplitude equalizer is installed on the route of the protection line and is used to compensate for fluctuations in amplitude frequency characteristics and pilot signal level in the baseband band in the IF band.

The plurality of detectors are each adapted to detect pilot signal levels and noise on the working lines and protection lines.

The control circuit controls the IF according to the detection level of the pilot signal.
This is for controlling the band variable amplitude equalizer.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of an IF band line switching device according to the present invention. In Figure 2, 11 to 14
are working line pilot signal and noise detectors, 2 are protection line pilot signal and noise detectors, and S
The Fi receiving end switch, 4#-iFMFM oscillator is an IF band amplitude equalizer, and the amount of equalization can be changed by an external control voltage. 6 is an amplitude equalizer 5 that operates according to the pilot signal level. This is a control circuit that outputs a control signal for control.

If an amplitude equalizer 5 in the IF band is inserted into the protection line and the equalization amount is changed by the output according to the fluctuation of the pilot signal level, the baseband amplitude characteristics and the fluctuation of the pilot signal level due to the switching of the line can be changed. It is possible to compensate for

Now, when one of the pilot signal detectors 11 to 13 of the working line detects an abnormality and drives the transmission @ side switch of the other station to transmit the signal of the working line to the protection line, the working line installed on the protection line A pilot signal detector 14 detects the pilot signal.

At this time, if the amplitude characteristics in the Cypeine band are degraded due to differences in transmission routes or equipment, this is detected as a drop in the pilot signal level. Based on the above-mentioned lowered detection level, the control circuit outputs a control signal a, and the equalization amount of the IF band amplitude equalizer 5 can be controlled in accordance with this output.

(Effect of the invention) As explained above, in the present invention, the backup line (KIF)
By configuring a band amplitude equalizer and a control signal that can output a control signal according to fluctuations in the pilot signal level, it is possible to convert the working line to the protection line, which is difficult to equalize in the baseband band. This has the advantage that it is possible to compensate for fluctuations in the amplitude characteristics in the baseband band and fluctuations in the pilot signal level that occur when switching lines.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the configuration of the receiving side of an IF band line switching device according to the prior art. FIG. 2 is a system diagram showing the configuration of an embodiment of the IP band line switching device according to the present invention. 11~14.2@--Detector 3...--Receiving end switch 4...φ--FM oscillator 5...IF band variable amplitude equalizer 6...Control circuit patent application People NEC Corporation Figure 1

Claims (1)

[Claims] An IP band line switching device that can switch between a working line and a protection line using a working/protection changeover switch, which is installed on the route of the protection line and is installed in the baseband band in the IF band. I to compensate for fluctuations in amplitude frequency characteristics and pilot signal level at
an F-band variable amplitude equalizer, a plurality of detectors for detecting the pilot signal level and noise in the working line and the protection line, and a standard IF band variable amplitude equalizer according to the detection level of the pilot signal. 1. An IP band line switching device comprising: a control circuit for controlling a converter.