JPS58161553A - Optical transmitting and receiving device of bipolar signal - Google Patents

Abstract

PURPOSE:To obtain an extremely excellent detecting characteristic, by converting the way of correspondence between the logic level of a bipolar signal and the intensity level of an optical signal. CONSTITUTION:A level converting circuit 6 converts signals of logic levels +1, -1 and 0 with correspondence to relative light intensity levels 1, 0 and 0.5 respectively. These converted signals are amplified by an amplifier 1 and then converted into optical signals having their intensity modulated by a light source 2. This modulated optical signal is transmitted along an optical fiber 3 and supplied to a level reconverting circuit 7 after detected by a photodetector 4 and then amplified by an amplifier 5. The circuit 7 converts the signals of receiving relative light intensity levels 1, 0 and 0.5 into signals of logic levels +1, 0 and -1 respectively. As a result, a system having excellent sensitivity for signal detection is obtained. This system does not increase noises even though it is used to an optical data bus to which many optical transmitters are connected at one time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides logic levels of 1+/'', 10'', @-l.
Optical transmission/optical transmission for optically transmitting bipolar signals with
This invention relates to a receiving device.

Conventionally, this type of device has had a configuration as shown in FIG. In the transmitting section of this device, "+/" shown in Figure 1 (1)
, ``Q'', ``-/'' logic level one bipolar signal is amplified by the amplifier 1, and the light source is 〉Figure 1 (
The signal is intensity-modulated and converted into a mourning light signal as shown in A. Here, the logic level "+l" becomes the light intensity level "l" (relative value) K, the logic level "-7" becomes the light intensity level "0",
Logic level “0” is light intensity level @ o, z II
K is supported. The electrical signal modulated in this way is
The light propagates through the 7-eyeper J, is detected by a photodetector, and is amplified by an amplifier j.

In this way, the Bybo 2 signal will be regenerated on the receiving side.

By the way, in such a conventional method, even when the signal is not being transmitted, that is, the logic @0" level continues, the optical signal has a relative value of "0. This method has the drawbacks of increasing power consumption and shortening the lifespan of the optical element, but this method is not suitable for optical data buses. In the case of nine cases, there were even bigger problems as described below.

That is, when optical fibers are used as a data bus line, many optical transmitters and optical receivers are connected to the seven optical fibers. The optical transmitters are controlled by a path controller, and each transmitter operates to emit signals in a time-division manner. Therefore, while one optical transmitter is operating, other optical transmitters do not emit signals. Expressing this using the logic level of bipolar signals, while one optical transmitter is transmitting logic level "+/" or 1-/", the other optical transmitters are transmitting logic level "θ". If the conventional method described above is used for this data bus line, when one optical transmitter emits light at a relative level of 0, All optical transmitters in the relative level 1Q,! In other words, many optical signals from many optical transmitters are transmitted simultaneously on the optical fiber path line, even though they are direct current.By the way, optical signal detection From the point of view of this relative value "0. ! r'' DC-like optical signal causes noise in the receiver. This is called signal noise, and as mentioned above, when there is high-level DC light, the signal detection characteristics 9. Normally, optical receivers use direct-coupled amplifiers whose frequency characteristics extend to direct current, but for such receivers, a direct current optical signal with a relative value of -4" greatly increases the operating point of the amplifier. This may cause the detection characteristics to deteriorate. As mentioned above, the conventional method has such major drawbacks.

The present invention is the ninth book to solve the above-mentioned drawbacks, and therefore, an object of the present invention is to convert the correspondence between the logic level of a bipolar signal and the intensity level of an optical signal, thereby achieving an extremely efficient The object of the present invention is to provide a novel optical transmitting/receiving means that can obtain detection characteristics.

The above object of the present invention is to provide logic levels "+/", ""0".

In an optical transmitting device and an optical receiving device that convert bipolar signals having a ``-i'v)s level into three types of optical intensities of relative optical intensity levels ``/'', ``o, s'', and 0'' and transmit them. , the logic levels ``+l'', ``0'' m, 1'' are converted into relative light intensity levels ``/'', ``2.''o, t'' according to this order, and are transmitted. Optical transmitter and receiving relative light intensity level 11
”, @O”, “o, !f” at logical level A/”+/”11
0”.

This is achieved by a bipolar signal optical transmitting/receiving apparatus characterized by comprising: an optical receiving apparatus configured to correspond to and convert .@, 1'' in this order.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1(3) shows the correspondence relationship between the logic level of a bipolar signal and the intensity level of an optical signal converted according to the present invention. As shown in the figure, the logic level of the bipolar signal is "+/", "-/"
","on is the light intensity level as follows"/","OH!
”, “ova” is supported (°+/”→11″
, '-/"→10.S" II, 7"→"O"). What is important here is that the logic level 00" of the Baba Bora corresponds to the light intensity level 10". As long as you are satisfied ("+l"→"O,S", "-/"→"7
″) conversion does not change the effect much.

FIG. 3 shows an embodiment of the present invention. This is obtained by adding a level conversion circuit 6 and a level reconversion circuit to the input section and output section of the conventional device shown in FIG. Level conversion circuit 6
The signal shown in FIG. 1 (j) is generated from the signal shown in FIG. 1 (1), and the level reconversion circuit 2 reproduces the signal shown in FIG. 2 (c) from the signal shown in FIG. 1 (3).

An embodiment of the level conversion circuit board is shown in FIG.

First, the θ level of the bipolar signal is detected by the 0 level detection circuit t. Here, the period at the θ level is 10
'', +/ or -l, a signal of ``''/'' is output.Then, the +l level detection circuit detects the +l level.Here, during the period of +/level, it outputs a signal of ``''/''. , other levels output a signal of 'o'. By adding these two output signals together, the waveform shown in Figure (J) is obtained.

FIG. 5 shows an embodiment of the level reconversion circuit 7.

In the figure, lO is a +//-l level detection circuit, // is a θ level detection circuit, and they are (3) in Figure 1, respectively.
&) or (b) is a determination circuit having a detection threshold level. +i/-t level detection circuit io outputs "+l" when +l, "-l" when -/ and 0,
The θ level detection circuit 1/ outputs @θ level when the O level is set to "7" level in other states.

By adding these two output signals together, the bipolar signal shown in FIG. 1(1) is reproduced.

Because of the configuration described above, the use of the present invention has the following advantages.

(C) Since the case where the optical transmitter sends out a "0" level corresponds to the state in which it does not send out light, noise will increase even if it is used in an optical data bus where many optical transmitters are connected at the same time. Therefore, a system with excellent signal detection sensitivity can be constructed.

(g) When used for applications where there is no need to send out light at the "θ" level, or in applications where signals are sent in bursts, the percentage of time that light is sent out becomes small, reducing the lifespan of one light emitting source. It can be extended.

Although the present invention has been described above with reference to one preferred embodiment thereof, it goes without saying that the ice field invention is not limited to the nine embodiments.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional device, FIG. 2 is a diagram showing a bipolar signal waveform, and FIG. 3 is a block diagram showing an embodiment of the present invention. 5 is a block diagram of a level conversion circuit, and FIG. 5 is a block diagram of a level reconversion circuit. l...Amplifier, Co...Light source, 3...Optical fiber,
D...Photodetector, S...Amplifier, 6...Level conversion circuit, F...Level reconversion circuit, t...θ level detection circuit, 9,...+/Level detection circuit, lO...+
l/-l level detection circuit, I/...O level detection circuit. Patent applicant: NEC Corporation Representative: Patent attorney Yutabe Kumagai

Claims (1)

[Claims] A bipolar signal having three logic levels "+/", @o", and -/" is defined as a relative light intensity level "l". '0. In an optical transmitting device and an optical receiving device that convert and transmit three types of optical intensities: “+l”, @ “, and −7”t, the relative optical intensity [v
11'', ``0'', and ``0.2'', and a phototrace transmitting device configured to correspond to and transmit the signals in this order, and receive relative optical intensity levels ゛l'' and ``θ''. 'o, s'' to logic level 1+/l', @'',
1. An optical transmitting/receiving device for nine bipolar signals, comprising: an optical receiving device configured to correspond to and convert ζ to @−7″ in accordance with the order of ζ.