JPS60111539A - Optical space propagation repeater - Google Patents

Abstract

PURPOSE:To improve the raliability while avoiding the effect of reflection by subtracting a pulse width for delay time's share corresponding to the delay time where an optical signal of a transmission section is reflected in an outer package, made incident to a photodetection section and superimposed on an input optical signal. CONSTITUTION:The optical signal 14 transmitted from a light emitting element 13 is reflected in the outer package, becomes, a reflected light 15, made incident to a photodetector 8, superimposed on an optical signal 9 incoming at the outside of the outer package and the pulse width is widened by the signal delay's share due to the reflection in the outer package and in the electric circuit. Since the delay is known in advance, the pulse width due to the delay is formed by a pulse generating circuit 16, subtracted from the pulse width superimposed so as to reproduce the input signal at the outside of the outer package. Thus, the deterioration of the transmission quality due to the effect of reflection in the outer package is avoided so as to improve the reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an optical space propagation repeater in an optical space propagation network.

[Prior art and intercondylar points]

In recent years, optical space propagation communication systems have been widely applied to office automation (OA).

This is an attempt to alleviate the future increase in the number of terminals and the increase in the number of connection cables, and uses space as a medium to connect terminals and exchange information using optical signals. In this communication method, an optical signal is transmitted between a wired optical space propagation communication device (hereinafter abbreviated as an optical transceiver) using space as a medium. This communication method has the advantage that it is easy to add, remove, and move terminals because the medium is space. In Figure 1, the optical signal is housed in an envelope (2) having a conventional optical ψ Pilter characteristic, and a part of the optical signal (4) sent out from the optical output section (3) is reflected light (
5) The light enters the light receiving section (6). Therefore, when receiving optical signals from optical transceivers, etc.,
The input optical signal from the optical transceiver and the optical signal.

The optical signal delayed by a certain time Δ by the ν heater is superimposed on the optical signal, and the optical signal is received by the optical pot beater, so that the pulse width of the optical signal is apparently widened. FIG. 2(a) is an input optical signal from the optical transceiver, and FIG. 2(b) is an optical signal which is inputted again to the optical V beater after being delayed by a predetermined period of time △ in the party competition Peter. This optical signal is reflected within the dome and enters the optical receiving section (b) of the optical ψ repeater.

FIG. 2(C) shows the output when the optical signals of FIGS. 2(a) and 2(b) are superimposed, input to a light receiving element, and passed through an amplifier.

FIG. 2(d) shows the waveform ν when the waveform further passes through the comparator. In the explanation of FIG. 2, the case where the process of reflection in the light ν Peter is performed once is explained, but in reality, the process of reflection is infinite. When reflected light is incident in this way, the transmission quality is greatly degraded, making it impossible to construct a highly reliable network.

In order to avoid the above-mentioned reflection problem, the conventional transceiver -> optical band Peter (uplink) route is different from the li! , I-wave number carrier waves are used, and mutual interference is avoided with an electrical filter. A so-called frequency-based multiplexing technique (F'DM) is used, but it has drawbacks such as the need to use high-speed light emitting/receiving elements in order to realize FDM, and the circuit scale becoming large.

[Purpose of the invention]

The present invention improves the drawbacks of the conventional optical space propagation communication system described above, and avoids deterioration of transmission quality due to the influence of reflected light within the envelope, and provides a highly reliable optical space propagation communication system. It is about providing.

[Summary of the invention]

The present invention inputs a pulse width for a delay time corresponding to the delay time when the optical signal sent from the output part of the light repeater is reflected within the envelope, enters the light receiving part, and is folded with the input optical signal. The effect of reflection is avoided by subtracting from the optical signal superimposed on the optical signal.

〔Effect of the invention〕

According to the present invention, it is possible to avoid deterioration of transmission quality due to reflection of optical signals within the envelope of a light shade repeater by a simple means, and to perform high-quality information communication. The use of space propagation communication is promoted, and the effect of eradicating wounds is achieved.

[One Practical Example of the Invention] Referring to all four drawings below, a practical example of the present invention will be explained - Electrical/Harmful, Part 1 - Schematic configuration of an optical conversion circuit.

An optical signal (9) enters the light receiving element (8) from outside the envelope, undergoes optical-to-electrical conversion, is amplified by an amplifier (flo), and is converted into a calibrator (old).
is converted into a digital code. This is operated by driver 〇 and converted into electricity by light emitting element (1).

The transmitted optical signal L141 is reflected within the envelope, becomes a reflected light (15), enters the light receiving element (8) again, is combined with the optical signal (9) coming from outside the envelope, and becomes a pulse light S1. It spreads by the amount of internal reflection and signal delay in the electric circuit. Since this delay can be known in advance, the pulse width due to this delay can be generated by the pulse generation circuit 11G) and added to the superimposed pulse width to reproduce the input signal from outside the envelope. It is.

FIG. 4(a) shows input signals from outside the envelope -/) 1, etc.
Is Figure 4(b) a reflection shadow? This is a signal with a wider pulse width. Figure 4 fc) shows the pulse generator circuit BI.
B) is a pulse created by knowing in advance the delay due to optical reflection within the envelope and the delay in the i44 circuit. By subtracting this from shi 44 obstacle 1 (b) force 1, Figure 4 (d)
is generated, which is exactly the same as the optical signal incident from outside the envelope.

Also, in this embodiment, the electrical output of the comparator is reduced by 7292 widths corresponding to the delay time, but as shown in FIG. 5, an appropriate waveform corresponding to the delay time is subtracted from the electrical output of the amplifier. But it is clear that it can be done as well. The effect of reflected light here is weak.

An attenuator 08) is inserted to match the level with the reflected light.

[Brief explanation of the drawing]

Figures 1 and 2 show conventional examples - Figures 1, 3 to 5
The figure shows one embodiment of the present invention. 1...Sil beater, 2...Envelope, 3...Light output section. 4.14... Optical signal, 5. Reflected light, 6... Optical receiver. 7. Ceiling, 8. Light-receiving terminal %9... Optical signal from outside the dome, 10. Hate chanter, ] Converter, 12 Driver, 13 Light emitting element, 15. Reflected light 16. Pulse generation circuit, 17 ... Delay element, 18... Attenuator. 1 generation! I! Person: Bento specialist Kensuke Norichika (lead or 1 person) Figure 2

Claims (3)

[Claims] (1) An optical space propagation repeater comprising: means for delaying a light reception detection signal for a certain period of time; and means for subtracting an electrical waveform obtained by the delaying means from the light reception detection signal. (2) The optical space propagation repeater according to claim 1, characterized in that the electrical waveform corresponding to the delay time is made into a pulse waveform and is logically subtracted from the pulse width of the comparator output. (3) The subtracting means subtracts the output from the amplifier using an analog circuit.
The optical space propagation repeater as described in .