JPS6326039A - Alarm circuit for deficient light receiving quantity - Google Patents

Abstract

PURPOSE:To offer a countermeasure such as checking of an optical connector by raising an alarm as the deficient light receiving quantity when a prescribed amount or over of pulse signal attended with a high frequency noise is outputted at an output of an optical receiver after a count means is reset. CONSTITUTION:If the luminous quantity of an optical signal inputted to the optical receiver 1 is deficient, an amplifier in the optical receiver 1 outputs a signal superimposed on the high frequency noise. When the level of the high frequency noise reaches nearly the same level as the reference level, lots of pulse signals are outputted in 1-bit time width in the output of the optical receiver 1 because of the high frequency noise. On the other hand, a counter 6 counts the pulse signal when the pulse signal attended with the high frequency noise is outputted from the optical receiver 1 while the clock pulse generated from a clock pulse generating circuit 4 is at an L level as shown in figure (c). When the counter 6 counts three pulse signals outputted from the optical receiver 1, an H level light receiving quantity deficiency detecting signal is outputted from its output terminal Y1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an alarm circuit for detecting insufficient amount of received light in an optical receiver including a photoelectric transformer that converts an optical signal into an electrical signal. The present invention relates to a light reception insufficient alarm circuit that issues an alarm in response to detection.

[Prior art 1] Optical receivers used in optical communications are photoelectric converters that convert optical signals into electrical signals! f! It has a built-in R. Such a light-receiving phlegm is known from Japanese Patent Publication No. 192155/1983. In such optical receivers, the photoelectric conversion detection power is used in a sufficiently larger area than the reference value (direct), and when the photoelectric conversion output is at the same level as the reference value, noise may cause incorrect discrimination. Sometimes.

[Problem to be Solved by the Invention 1] In the above-mentioned optical receiver, the amount of light received decreases due to poor connection of the optical connector, disconnection of the optical fiber, deterioration of the light emitting source at the other station, etc., and the photoelectric conversion output decreases to 1ull.
- When it reaches the same level as the value, it is necessary to detect this and issue an alarm.

Therefore, the main object of the present invention is to provide a light receiving amount insufficient alarm circuit which detects a shortage of light receiving amount in an optical receiver and issues an alarm.

Means for solving peaks between c] The present invention provides an insufficient amount of received light alarm circuit that detects an insufficient amount of received light m and issues an alarm in an optical receiver including a photoelectric converter that converts an optical signal into an electrical signal. There is a clock pulse generating means that generates a clock pulse with a width wider than the pulse width included in the received signal received by the optical receiver, and a clock pulse generating means that generates a clock pulse with a width wider than the pulse width included in the received signal received by the optical receiver. A counting means that counts the pulse signals and outputs an insufficient amount of received light detection signal when the counted value exceeds a predetermined value; and warning means for issuing a warning of insufficient quantity.

[Function] The insufficient amount of received light alarm circuit according to the present invention detects that the amount of received light is insufficient when a pulse signal accompanying high frequency noise is output from the optical receiver at a predetermined value or more after the counting means is reset. It is possible to issue an alarm as if there is a problem.

[Embodiments of the invention] FIG. 1 is a schematic block diagram of an embodiment of the present invention.

First, the configuration of an embodiment of the present invention will be described with reference to FIG. The optical receiver 1 is, for example, the one described in Japanese Patent Publication No. 57-192155 mentioned above, and an optical fiber 2 is connected to the optical receiver 1. The optical receiver 1 converts the optical signal transmitted from the optical fiber 2 into an electrical signal using a photoelectric converter, and amplifies the converted electrical signal using an amplifier and outputs the amplified signal. The output of the optical receiver 1 is given to a signal processing circuit 3 and first and second counters 6 and 7.

The signal processing circuit 3 performs processing such as serial-parallel conversion on the output of the optical receiver 1. A clock pulse generated by the clock pulse generation circuit 4 is applied to the counter 6 as a clear signal. The pulse width of the clock pulse generated by the clock pulse generation circuit 4 is selected to be approximately twice the pulse width of the pulse signal included in the output of the optical receiver 1. Further, the polarity of the clock pulse generated by the clock pulse generation circuit 4 is inverted by the inverter 5, and the clock pulse is given to the counter 7 as a clear signal. The counters 6 and 7 count pulse signals accompanying high frequency noise from the output of the optical receiver 1 during a period when either one is cleared by a clock pulse, and for example, a 74L8393 is used.

When counters 6 and 7 count pulses associated with high-frequency noise exceeding a predetermined value, their respective output terminals Y1
．． A detection signal of insufficient amount of received light is output from Y2.

This light reception insufficient detection signal is applied to an input terminal A of a flip-flop 9 via an OR gate 8. The flip-flop 9 is set in response to the detection signal for insufficient amount of received light, and provides an 'l-1' level signal from its output terminal Z to the base of the transistor 10, such as a 74L810.
7 etc. are used.

A series circuit of a resistor 12 and a light emitting diode 11 is connected to the collector of the transistor 10. Further, a reset switch 13 is connected to the flip-flop 9.

FIG. 2 is a waveform diagram of each part of FIG. 1.

Next, with reference to FIG. 1 and FIG. 2, a specific operation of an embodiment of the present invention will be described.

When the optical signal transmitted from the optical fiber 2 is given to the optical receiver 1 and the amount of received light is sufficiently larger than the reference level shown in Fig. 2<a>, the optical receiver 1 rises to the "H11 level" Output a signal.

On the other hand, the clock pulse generating circuit 4 generates a clock pulse having a pulse width t2 that is approximately twice the pulse width t1 included in the output of the optical receiver 1, and supplies the clock pulse to the counter 6. Further, this clock pulse is inverted by an inverter 5 and applied to a counter 7.

The counters 6 and 7 are reset when the clock pulse is at the "H" level, and their outputs Y1 and Y2 are at the "L" level and do not output an insufficient amount of received light detection signal.

However, when the amount of light of the optical signal input to the optical receiver 1 is insufficient, the bottle width device included in the optical receiver 1 is
), a signal on which high-frequency noise is superimposed is output. When the level of this high frequency noise becomes approximately the same level as the reference level, the output of the optical receiver 1 becomes
As shown in Figure (b), many pulse signals are output in the time width of one bit due to high frequency noise.

On the other hand, as shown in FIG. 2(C), the counter 6 detects the high frequency noise from the optical receiver 1 when the clock pulse generated from the clock pulse generation circuit 4 is at the "L'° level." When the pulse signal is outputted, the number of pulses Ff3 is counted. And the counter 6 is the optical receiver 1
When three pulse signals are counted, a detection signal of an insufficient amount of received light at the 11 HIT level is output from the output terminal Y1. This light reception insufficient detection signal is applied to the input terminal A of the flip-flop 9 via the OR gate 8, and the flip-flop 9 is set as shown in FIG. 2(e). When flip-flop 9 is set, an "H" level signal is applied from its output terminal 2 to the base of transistor 10. In response, the transistor 10 becomes conductive, current flows to the light emitting diode 11 via the resistor 12, and the light emitting diode 11 lights up as shown in FIG. 2(f), indicating that the amount of light received is insufficient. .

In this way, the light emitting diode 11 is turned on when the amount of light received is insufficient, so the user can immediately know when the amount of light received is insufficient by looking at the display, and can take countermeasures such as checking the optical connector. You can take it.

[Effects of the Invention] As described above, according to the present invention, when a pulse signal accompanying high frequency noise is output from an optical receiver in response to a shortage of received light, the pulse signal exceeds a predetermined value. If so, an alarm will be issued so that countermeasures such as checking the optical connector can be taken based on the alarm.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram of an embodiment of the present invention. FIG. 2 is a waveform diagram of each part of FIG. 1. In the figure, 1 is an optical receiver, 2 is an optical fiber, 3 is a signal processing circuit, 4 is a clock pulse generation circuit, 5 is an inverter, 6.7 is a counter, 8 is an OR circuit, 9 is a flip-flop, and 10 is a transistor , 11 is a light emitting diode,
13 indicates a reset switch. Figure 1

Claims (2)

[Claims] (1) In an optical receiver including a photoelectric converter that converts an optical signal into an electrical signal, a received light amount insufficient alarm circuit detects an insufficient amount of received light and issues an alarm, the received signal being received by the optical receiver. a clock pulse generating means for generating a clock pulse having a width wider than a pulse width included in the optical receiver; a counting means for counting pulse signals and outputting a detection signal for detecting insufficient amount of received light when the counted value exceeds a predetermined value; An insufficient amount of received light alarm circuit, comprising an alarm means for issuing an alarm for insufficient amount of light. (2) The counting means includes a first counting means that is reset by a clock pulse generated from the clock pulse generation means, and a clock pulse that is reset by a clock pulse whose polarity is inverted from the clock pulse generated from the clock pulse generation means. 2. The insufficient amount of received light alarm circuit according to claim 1, further comprising: a second counting means for calculating the output of the first and second counting means; and means for supplying one of the outputs of the first and second counting means to the alarm means.