JPS588618B2 - Denso Urono Pilot Warmer Warmer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an alarm circuit that detects fluctuations in a pilot signal and issues an alarm in a repeater installed on a transmission line.

A multi-relay transmission system is widely known in which a frequency is selected within a transmission bandwidth and automatic gain adjustment is performed based on a pilot signal transmitted at a constant level.

This system generally also monitors the pilot signal level, and is equipped with an alarm circuit that issues an alarm when the pilot signal level fluctuates beyond a certain standard alarm width.

This standard alarm width is set relatively wide to prevent alarms due to malfunctions, and is generally ±3 dB in Japan's broadband coaxial transmission system.

On the other hand, the pilot signal is also used when adjusting the reference gain of the repeater separately from this alarm circuit.

That is, when adjusting the reference gain during the initial setting of the repeater, etc., the automatic gain adjustment function is artificially stopped and the reference gain of the repeater is adjusted so that the pilot signal level becomes a specified value.

In this case, the allowable deviation from the specified value is selected to be considerably narrower than the reference alarm width described above, taking into consideration the level diagram and the signal-to-noise ratio due to overload.

In Japan's broadband coaxial transmission power system, ±0.5 dB is common.

For this reason, when adjusting the reference gain, a special measuring device is required to detect and measure the pilot signal level, and it is difficult to adjust the repeaters that have been installed in manholes and on utility poles in recent years. However, there are notable drawbacks, such as the need for a separate power source for the measuring instrument.

In order to eliminate such drawbacks, the present invention aims to improve the alarm circuit so that it can also be used when adjusting the reference gain.

The present invention is characterized in that when the automatic gain adjustment function is artificially stopped, the alarm reference width of the alarm circuit of the repeater becomes narrower.

This will be explained in detail below using the drawings.

FIG. 1 is a diagram showing an example of the configuration of a repeater embodying the present invention.

In the figure, 1 is the input, 2 is the reference gain adjustment circuit, 3 is the variable gain circuit, 4 is the amplifier circuit, 5 is the output, 6 is the pilot filter circuit, 7 is the pilot amplifier circuit, 8 is the control circuit, and 9 is the alarm circuit. , 10 indicates the alarm output.

Input 1 is coupled to the input of amplifier circuit 4 via reference gain adjustment circuit 2 and variable gain circuit 3.

The output of the amplifier circuit 4 is led to an output terminal 5, and is also branched and coupled to a pilot amplifier circuit 7 via a pilot filter circuit 6.

This output is branched and coupled to a control circuit 8 and an alarm circuit 9.

The output of the control circuit 8 is coupled as a control signal to the variable gain circuit 3, and an automatic/manual switching signal is also led to an alarm circuit 9.

The output of alarm circuit 9 is coupled to alarm output 10.

An input signal applied to input 1 is amplified by amplifier circuit 4 and sent to output 5.

At this time, the reference gain adjustment circuit 2 determines the center gain value of this repeater, and is constituted by a manual variable loss circuit.

Further, the variable gain circuit 3 is a loss circuit network that changes depending on a control signal when automatic gain control is performed.

A pilot signal is extracted from the output signal appearing at the output 5 by a pilot filter circuit 6 and amplified by an amplifier circuit 7.

This output is compared with a reference level in the control circuit 8, and a control signal is sent to the variable gain circuit 3 such that the output is always at the reference level.

The alarm circuit 9 also monitors the pilot signal level and
Only when this exceeds a certain alarm reference width, alarm output 1
Sends output to 0.

The normal alarm reference width is ±3.0 dB, as shown by the diagonal line downward to the left in FIG.

Next, when adjusting the reference gain of this repeater, the manual/automatic changeover switch of the control circuit 8 is operated to change over to manual.

As a result, the control signal to the variable gain circuit 3 is fixed.

At the same time, a signal indicating the manual state is sent to the alarm circuit 9, and the alarm reference width of the alarm circuit 9 is narrowed to ±0.5 dB, as shown by the diagonal line downward to the right in FIG.

If the reference gain adjustment circuit 2 is operated and adjusted so that the alarm output is not issued in this state, the reference gain will be ±0.5d.
It will be adjusted within B.

At this time, there is no need for a special measuring device or power source for measuring the pilot signal, and appropriate adjustments can be easily made while observing the alarm output.

In particular, if there is a circuit that emits a sound for the alarm output, it will be possible to adjust the reference gain while listening.

The alarm circuit 9 is normally configured to issue an alarm using a meter relay, so if the current supplied to the meter relay is applied through a switching type loss circuit and switched in response to manual/automatic switching in the control circuit 8, Can be easily configured.

Further, in the case of an electronic circuit, the comparison reference voltage for alarm generation may be changed in accordance with manual/automatic switching.

As described above, by adding extremely simple improvements according to the present invention, it is possible to obtain a repeater that does not require a special pilot signal measurement device when adjusting the reference gain.

In particular, adjusting work for repeaters installed in manholes or on utility poles eliminates the need for measuring instruments and power supplies to operate them, which saves money and improves work efficiency.

Note that the insertion positions of the reference gain adjustment circuit and the variable gain circuit described in the above embodiments are not limited to those shown in FIG. The present invention can be implemented in the same way even if it is configured as a part of.

It goes without saying that the numerical values of the levels and the like shown in the explanation of the above examples do not limit the scope of the present invention, and that appropriate levels and the like of the respective applied devices can be selected.

[Brief explanation of the drawing]

FIG. 1 is a configuration example diagram of a repeater embodying the present invention. FIG. 2 is an explanatory diagram showing how the standard alarm width changes. 1...Input, 2...Reference gain adjustment circuit, 3...Variable gain circuit, 4...Amplification circuit, 5...Output , 6... Pilot signal filter circuit, 7... Pilot signal amplification circuit,
8...Control circuit, 9...Alarm circuit, 1
0...Alarm output.

Claims (1)

[Claims] 1. An automatic gain adjustment circuit that adjusts the gain of a repeater inserted into the transmission path so that the pilot signal sent to the transmission path has a constant level at the repeater inserted into the transmission path; an alarm circuit that issues an alarm when the output pilot signal level fluctuates beyond an alarm reference limit; and the automatic gain adjustment circuit is configured such that the automatic gain adjustment operation can be artificially stopped. In a pilot signal alarm circuit for a road, when the operation of the automatic gain adjustment circuit is artificially stopped, the alarm reference width of the alarm circuit connected to the output of the circuit becomes narrower, and the pilot signal level becomes lower than the alarm. A pilot signal alarm circuit for a transmission line, characterized in that the reference gain of a repeater can be adjusted by operation so that the value falls within a reference width.