JPS58204644A - Optical network monitor - Google Patents

Abstract

PURPOSE:To support the network control by means of the CSMA-CD system effectively, by using an optical distributor constituted so as not to fold back a transmitted optical signal to the own station, and detecting collision of data effectively. CONSTITUTION:The optical distributor 1 has the directivity not folding back the transmitted optical signal from the own station and connected to a bus 2 comprising optical fibers to constitute an optical network. The state of transmission of a transmission signal T from the optical transmitter 3 is detectecd at a display 5. On the other hand, an output of an optical receiver 4 is given to a gate 6 and a shift register 7 as a clock. An FF8 is set with an output of the register 7, and its receiving state detecting signal and a transmitting state detecting signal by the display 5 are processed 11 for logical product, and through the result of the processing, the generation of collision of data in the network 2 is detected and discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical network monitoring device that can accurately detect data collisions in an optical network.

[Technical background of the invention and its problems]

As a network control method with characteristics suitable for office automation systems,
8MA-CD (Carrlsr S@nae
Multiple Ae*mm-Co11ision
The Det@ction) method is known. This method uses coaxial cables exclusively to construct a network communication network, and is often used as a share in relatively expensive releases such as data file servers that accompany the development of the information society.

However, recently, the price of network equipment has increased. Optical networks have attracted attention as an economical network system with reduced installation costs, and the C8MA-C
It is expected that it will support the D method. However, it is very difficult to implement the CBMA-CD method t+ port in an optical network composed of conventionally known optical branching elements, and there are many problems.

That is, when information is communicated via a network using the C8MA-CD method, it is necessary to monitor and avoid data collisions on the network. However, in an optical network composed of optical branching elements, the intensity deviation of the received optical signal is generally large, so it is difficult to detect and determine the simultaneous presence of multiple lights (K) using conventional analog means. Furthermore, even in the original star-cassilla network, where the intensity deviation of the received optical signal is relatively small, the total deviation due to optical transmission output, optical connectors, optical cable loss, star-cassillary deviation, etc. can be reduced to 3 dB. It would also have been economically disadvantageous to try to ensure a top 6 ranking by keeping the score below.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and its purpose is to monitor the state of the source network and collect data regardless of the intensity deviation of the nine bows communicated via the optical network. Collision can be detected and C3
A practical optical network monitoring device that can effectively support network communication using the MA-CD method.
Our goal is to provide the following.

[Summary of the invention]

The present invention configures an optical network using an optical splitter configured so that the transmitted light from its own station is not returned to the own station, and the receiving board of the optical splitter of this optical network. When the signal obtained at the time is equal to or more than a predetermined number of bits within a certain period of time, this is detected as a reception wave, and the transmission state of the station is also detected to find the correspondence between this transmission state and reception state.・Th of data in the J6 Pi9 network
It is designed to determine whether arrows are drawn or not.

〔Effect of the invention〕

Therefore, according to the present invention, data collision in an optical network can be easily and reliably determined and detected by direct signal processing. Moreover, since the reception state is detected by detecting a signal with a predetermined number of bits or more within a predetermined time, even if the own station's transmitted signal is received discretely by mistake due to imperfections in the optical splitter, this will not occur. can be effectively removed and reliable judgments can be made. And as mentioned above, 2
Since digitization processing is possible, the processing circuit can be constructed at low cost, which has many practical advantages. Therefore, C8MA
- It becomes possible to construct a highly practical optical network system by effectively using the CD system.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an embodiment device. The optical splitter 1 must be of a directional type that does not return the source key signal from its own station to the above-mentioned own station, and is connected to the data bus 2 consisting of the original fiber to form an optical network. There is. An optical transmitter 3 of the station is connected to the sending port of the optical distributor 1, and an optical receiver 4 is connected to the receiving port. The transmission signal T transmitted via the optical transmitter 3 is then sent out from the optical distributor 1 to the data bus 2 and
(1) is received and input to the optical receiver 4 from the receiving/paying boat.

By the way, the transmission signal T transmitted from the optical transmitter 3 is input to the transmission=a indicating device 5, and its transmission state is detected. This transmission state detection is performed by detecting the presence or absence of transmission No. 18 from, for example, bit changes in transmission r-even. On the other hand, the received output of the optical receiver 4 is guided to a gate circuit 6 and is also inputted to a shift register 7 as a clock signal. This 77 Trenostar 7 has data “l”
``r'' Each time the original receiver 4 generates the received output ``1#'', it is manually inputted and transferred. So, if the input output "1" has occurred a fixed number of times, then the output of the shift reno stave will cause the flip-flop 8 to be output. ; It is now set. The dart circuit 6 is opened by this setting of the Fritunoflora f8, and the received output from the optical receiver 4 is stored in a processing circuit (not shown) of the station.

In addition, the shift register 7 and the flip-flop sFi,
The clock signal oscillated by the oscillator 9 is frequency-divided by the frequency divider 10, and is reset every eight time slots, for example. As a result, the reception state detection by the shift reno stub and the fling flop f8 is performed every 8 time slots, and the fling flop f8
"1# data" is set when the receiving state is detected.

The receive state detection signal 1d set in the free lag flop 8 and the send state detection signal detected by the transmitter display device 5 are supplied to the AND circuit 11 and subjected to AND processing. ing. Based on this AND result, when a reception signal state occurs during the transmission state of the station, it is detected and determined that this is a data collision occurrence in the optical network 2. The result of this determination is then output via the f-) circuit 12 every time slot.

Thus, according to the present device, since no reception output is originally generated when the own station is transmitting a signal, it is possible to effectively detect an r-event collision entering the optical network by detecting the reception signal. However, if the isolation between the transmitting and receiving boats is defective (due to manufacturing imperfections in the optical splitter 1), the transmitter 6 of the own station may slightly overwhelm the 48 aircraft 4. There is. It is difficult to distinguish this signal from signals from other stations, and therefore there is a risk that an erroneous reception state determination will be made. In this case, it is determined that the carrier sense signal from another station is negative, and as a result, there is a possibility that the signal method (ij) from the own station is lost in order to avoid data collision.Therefore, such a problem In order to avoid this, &C needs to have a function such as ignoring signals below a certain value.

Next, the optical reception power in the optical receiver 4 and its sign 1i4
When considering the 9 rate, the relationship is generally shown as shown in Figure 2. That is, as for the bit error rate with respect to the optical reception power, the higher the optical reception power is, the higher the optical reception power becomes. Therefore, in order to ensure reliable signal 1 detection, it is necessary to ensure that the power of signal 16, which is communicated from other stations, is greater than or equal to 21, as shown by f+ line area A in Figure 2. Become.

In addition, in order to prevent the reception input (g) caused by the imperfection of the optical splitter 1, the power of the unnecessary signal must be suppressed to below P2 as shown by the shaded area B in Figure 2. is also required.

On the other hand, when a pre-receiving ignition device 4 equipped with an automatic identification threshold control function is used, the code error rate is as shown by the solid line C, and the optical receiver 4 mistakenly receives data “1”. The probability of outputting `` will be shown in the figure below. However, in order to prevent reception letter 11!A from being detected even when the signal from the own station is distorted even when the g unit 4 has all of these characteristics, it is necessary to have the above two characteristics C. , D is the performance shown in the previous b
It is necessary that it not be included in U2 diagonally shaded areas A and B.

Therefore, in order to satisfy such conditions, the specifications required for the optical receiver 4 include the reception power width (P'I
It is essential to make the width of P's as narrow as possible and to reduce fluctuations in the above characteristics C and D.

However, if we pay attention to the percentage shown in the breakdown, the signal generation in this region is discrete, so taking this into consideration, the burden on the optical receiver 4 can be reduced to a considerable extent.

Based on the above considerations, even if a small amount of MjA interference signal is generated due to imperfections in the optical splitter 1, since the image signal is discrete, the transmission code may be a pit sequence such as a Manchester code.・If it is an inf” pendant, as mentioned above, by shifting the number of bits within a predetermined time to the 1 side using shift reno stuff, erroneous reception state detection due to a loop signal can be prevented.
It becomes possible to stop.

Thus, according to the present device, the receiver 4 within a predetermined time
Since the number of output bits is measured, even if the code error rate is quite low when receiving signals from other stations, the reception state can be detected by setting the free lag flop 8 almost constantly. obtain. In addition, even if a reception output is generated due to the spider-intrusion signal in #1, this signal will be transferred to the shift register 1 within a predetermined time.
Since the signal does not pass through the F, this discrete unnecessary signal can be effectively eliminated. Therefore, it is possible to perform reliable reception state detection here. In addition, with the output of Fritsuno Frog 8 detected in this way, r-)
Even if the circuit 6 is controlled, reception interference will not be caused.

As explained above, according to the present invention, data collisions in optical networks can be effectively detected, and C8
Network control using the MA-CD method can be effectively supported.

Moreover, the conditions for the received optical power p in the optical receiver 4 can be significantly relaxed, and the manufacturing margin for the optical receiver 4 can be greatly expanded, making it possible to manufacture the optical receiver 4 simply and at low cost. ■Becomes Noh. Furthermore, the optical distributor 1
This increases the tolerance for imperfections and facilitates fabrication. Therefore, it is possible to realize an optical network at low cost, and its reliability can also be improved.

Additionally, false collision detections for optical networks are prevented, and the occurrence of additional carrier sense conditions is prevented. As a result, sufficient opportunities to access the optical network are ensured, and great practical advantages such as the ability to effectively operate the optical network based on the C8MA-CD system are achieved.

Note that the present invention is not limited to the above embodiments. For example, it is also possible to detect the reception state in an analog manner. Further, the time period for detecting the receiving state, the number of bits for determining the receiving state, etc. may be adjusted depending on the purpose of signal communication in the photon network. Furthermore, the oscillation frequency of the oscillator 9 is determined by the number of oscillation waves transmitted through the optical network 2.
The transmitted light may be set to the same degree as the Net Cook code speed in No. 3. In summary, the present invention can be implemented with considerable modification without departing from the gist thereof.

4. Brief explanation of the drawings.

! Figure 1 is a schematic block diagram showing an embodiment of the present invention, and Figure 2 is a diagram showing the relationship between received optical power and code error rate in an optical receiver.

DESCRIPTION OF SYMBOLS 1... Optical distributor, 2... Data bus, S... Optical transmission, J machine 2, 4... Optical receiver, 5... Transmission display device, 6°12...c - circuit, y... shift register, 8... fritsuno 70 sozo, 9... oscillator, 1o.
...For frequency division;, 1)...AND circuit.

Claims (1)

[Claims] A transmitter F6 that detects the original transmission status of a station connected to an optical network via a directional optical splitter that does not output the optical transmission signal from the own station to the receiving port of the own station. A state detector and a receiver'+M? of the directional light distributor. -) When the optical signal output to the optical signal has a predetermined number of bits or more within a predetermined time, the reception state detector detects the optical signal as a No. 4 reception state and the logical product of the detection results of these state detectors is calculated. An optical network monitoring device comprising: means for detecting a collision of optical signals in the optical network.