JPH05167539A - Optical communication system - Google Patents

Abstract

PURPOSE:To attain light reception and conversion by surely separating a reflected optical signal from a regular optical signal when outgoing incoming call control is simultaneously implemented in the case of outgoing incoming call control of the optical communication system. CONSTITUTION:This system is provided with oscillators 2,3 controlling a light emission interval of electrooptic converters 4,5 different between a station equipment and a subscriber equipment and with received light strength detectors 6,7 detecting a peak of the optical signal received at a time interval other than the light emitting time decided by the oscillators 2,3 to detect the light receiving level. Thus, the effect of preventing a dead lock of the outgoing incoming call control procedure is obtained.

Description

Detailed Description of the Invention

[0001]

The present invention is used in an optical subscriber communication system. In particular, it relates to an incoming / outgoing call control means for single-path bidirectional communication by optical burst communication.

[0002]

2. Description of the Related Art In a conventional example, it is constructed by ignoring reflection on an optical communication path which is an intermediate path. Therefore, when using a light path with a large reflection level,
When the station device and the subscriber device are asynchronous during the call origination / receipt procedure, a light reception error may occur.

[0003]

In the conventional example, when an optical signal for an incoming / outgoing call is simultaneously sent out by the station device and the subscriber device, which are devices at both ends of the optical communication path, or when the outgoing call or the incoming call is made. When an incoming or outgoing call occurs during the time until the detection of the call signal, the station device and the subscriber device need to emit light and receive light at the same time. And a signal in which the light emission signal of its own device is reflected on the way. Therefore, depending on the relationship between the level of the regular received signal and the level of the reflected signal, the light emitting state of the opposite device may not be recognized correctly, and both devices may deadlock and communication may not be possible.

The present invention eliminates such drawbacks, and an object of the present invention is to provide an optical communication system having means for preventing a deadlock of an incoming / outgoing call control procedure.

[0005]

The present invention comprises a station apparatus and a subscriber apparatus connected by an optical path having the same transmission / reception path of burst-like optical signals transmitted / received to / from the station apparatus. , Each of the station device and the subscriber device, a converter for converting an electric signal to be sent to an optical signal, an oscillator for determining a light emission time interval, a detection circuit for detecting the level of the received optical signal, In an optical communication system including a conversion circuit for converting a received optical signal into an electric signal, a light emission interval control for setting the frequencies generated by the oscillators of the station device and the subscriber device to be relatively prime at the time of an incoming / outgoing call It is characterized by comprising means.

Here, it is preferable that the detection circuit includes means for performing peak detection of an optical signal received at a time interval other than the light emission time interval determined by the oscillator at the time of making or receiving a call.

[0007]

In the control of outgoing / incoming calls, the light emission interval is controlled to be different between the station device and the subscriber device, and the light reception level is detected by performing peak detection of the light signal received at time intervals other than this light emission time interval. .. This prevents deadlock in the incoming and outgoing call control procedure.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of this embodiment.

In this embodiment, as shown in FIG. 1, the station device 11 and the optical path 1 having the same transmission / reception route of burst-like optical signals transmitted / received between the station device 11 are connected. Station device 11 (subscriber device 12)
Is an electro-optical converter 4 (5) which is a converter for converting an electric signal to be transmitted into an optical signal, an oscillator 2 (3) for determining a light emission time interval, and a detection circuit for detecting the level of the received optical signal. Received light intensity detector 6 (7) and photoelectric converter 8 which is a conversion circuit for converting the received optical signal into an electric signal.
(9), and as a feature of the present invention, the oscillator 2 included in the station device 11 and the subscriber device 12
The light emitting interval control means 10 sets the frequencies generated by (3) to be relatively prime at the time of outgoing and incoming calls, and the detection circuit receives light at time intervals other than the light emitting time intervals determined by the oscillators 2 and 3 at the time of outgoing and incoming calls. It includes means for performing peak detection of the optical signal.

Next, the operation of this embodiment will be described. Figure 2
Is an example of temporal change of the transmitted / received light intensity pattern. The station device 11 uses the electro-optical converter 4 to emit light at time interval f ₀ for controlling incoming calls. The subscriber unit 12 has a time interval f ₁ (f ₁ ≠ f ₀ ) for call control.
Then, the electro-optical converter 5 is used to emit light shown at level 102 in FIG. At this time, the light reception level of the station device 11 is the level 1 obtained by adding the reflection level 111 to the regular light reception level 110.
Will be 04. The level is 106 in the subscriber device.
At this time, the peak values are detected by the received light intensity detectors 6 and 7 at intervals other than the light emission interval f ₀ or f ₁ of the electro-optical converter 4 or 5, and the peak value is detected by the opto-electric converters 8 and 9. Is converted to the reception result. That is, the peak value of the reflection level 111 can be easily known from the light emission interval of the electro-optical converter of the device itself, so that it is not detected.

[0011]

As described above, according to the present invention, the light emitting interval between the station device and the subscriber device is changed so that the light receiving level can be stably received regardless of being modulated by the reflected light. Since it is possible to detect the received light signal of the above, there is an effect that it is possible to prevent the deadlock of the incoming / outgoing call procedure that occurs due to the simultaneous outgoing / incoming calls that may occur at the beginning of communication.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a waveform chart showing the operation of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical path 2, 3 Oscillator 4, 5 Electro-optical converter 6, 7 Received light intensity detector 8, 9 Photo-electric converter 10 Light emission interval control means 11 Station device 12 Subscriber device

Claims (2)

[Claims] 1. A station apparatus and a subscriber apparatus connected by an optical path having the same transmission / reception path of burst-like optical signals transmitted / received between the station apparatus and the station apparatus and the subscriber. Each of the devices includes a converter that converts an electric signal to be sent to an optical signal, an oscillator that determines a light emission time interval, a detection circuit that detects the level of the received optical signal, and an electric signal that receives the received optical signal. In an optical communication system including a conversion circuit for converting, a light emission interval control means is provided for setting the frequencies generated by the oscillators of the station device and the subscriber device to be relatively prime at the time of incoming and outgoing calls. Optical communication system. 2. The optical communication system according to claim 1, wherein the detection circuit includes means for performing peak detection of an optical signal received at a time interval other than the light emission time interval determined by the oscillator when making or receiving a call.