JPS62116044A - Phase modulating system - Google Patents

Abstract

PURPOSE:To eliminate bad influences to the code error rate characteristic in the in-service monitoring system of a repeater, by providing the 2nd discrimination circuit on the output side of the discrimination circuit of the repeater and phase-modulating clock signals inputted to the 2nd discrimination circuit. CONSTITUTION:At a discrimination circuit 1 the input signal shown in Fig. (A) is discriminated at the clock of a main transmission line shown in Fig. (B) showing the output of a timing circuit 2. The discriminated waveform which is free from noises and has a rectangular shape as shown in Fig. (C) is inputted to another discrimination circuit 4 and the input signal is discriminated at the clock shown in Fig. (D) which is obtained by phase-modulating the clock of the output of the timing circuit 2 by means of a phase-modulator circuit 3. Namely, the clock which is the output of the timing circuit 2 is phase- modulated by a phase modulator circuit 3 and, even when the discrimination point moves from a point (d) to another point (e) or (f), the eye pattern is not narrowed and no noise is produced. Accordingly, even when alignment jitters are accumulated because of multiple repeating transmission, the code error rate characteristic is free from any bad influences.

Description

[Detailed Description of the Invention] [Summary] In an in-service monitoring system for a repeater, a second identification circuit is provided on the output side of an identification circuit within the repeater, and a phase difference is applied to a clock signal input to the second identification circuit. By applying modulation, it is possible to avoid adversely affecting the bit error rate characteristics.

[Industrial application field]

The present invention relates to an improvement in a phase modulation method of an in-service monitoring method in which monitoring information for monitoring the code error rate of an optical repeater, etc., is transmitted to a terminal station by phase modulation of a main transmission clock signal, for example.

In the phase modulation method described above, it is desirable that the bit error rate characteristics not be adversely affected even when alignment jitter accumulates due to multiple repeat transmission.

[Conventional technology]

Figure 3 is a block diagram of the conventional example, Figure 4 is a time chart of waveforms of each part in Figure 3, and (A) and (B) are a and b in Figure 3.
corresponds to the point.

In the figure, 1 is an identification circuit, 2 is a timing circuit, and 3 is a phase modulation circuit.

The waveform of the digital signal sent to the repeater is blunted by the bandwidth of the equalizing amplifier to optimize the S/N of the discrimination point in the discrimination circuit 1, and at the input of the discrimination circuit 1, the waveform becomes dull. The eye pattern waveform is accompanied by noise generated on the receiver 8 side as shown in FIG. 8A.

The clock is extracted from this waveform by the timing circuit 2,
The clock shown by the solid line in FIG. 4(B) is output.

For example, 21KHz is applied to this clock in the phase modulation circuit 3.
Phase modulation with a phase modulation width P-P of 30 degrees is performed, and at the rising point of this phase-modulated clock, the discrimination circuit 1 discriminates between O and 1, and the phase-modulated discrimination result is By outputting, the monitoring information of the repeater is transmitted to the terminal station.

[Problem that the invention seeks to solve]

However, when there is no phase modulation, the discrimination point is d in Figure 4.
Even if the eye pattern is wide and there is some jitter, code identification errors will not occur. However, if phase modulation is used to move the identification point to points A and C, identification will occur in a narrow area of the eye pattern, which may cause noise. The influence is also large, and when alignment jitter accumulates due to multiple repeat transmission, there is a problem that it adversely affects the bit error rate characteristics.

[Means for solving problems]

The above problem is due to the fact that there is a second
This problem is solved by the phase modulation method of the present invention, in which a second identification circuit (4) is provided, and phase modulation is applied to the clock (No. 8) input to the second identification circuit (4).

[Effect]

According to the present invention, the noise is removed from the waveform identified by the identification circuit (1), and in the case of 1, it becomes a rectangular waveform. In this case, even if the clock moves due to phase modulation, the eye pattern will not become narrower and there will be no noise, so alignment can be achieved by transmitting multiple times. Even if jitter accumulates, it will no longer have an adverse effect on the bit error rate characteristics.

〔Example〕

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a time chart of waveforms of each part in Fig. 1, and (A) to (D) are the first
This corresponds to points a w and d in the figure.

In the figure, numeral 4 indicates an identification circuit, and the same reference numerals indicate the same functions throughout the figures.

The difference between FIG. 1 and FIG. 3 is that the identification circuit 1 receives the input signal shown in FIG. 2(A) using the main transmission line clock shown in FIG. The identified rectangular waveform without any noise shown in FIG. The difference is that the clock shown in FIG. 2(D), which is phase-modulated by the modulation circuit 3, is used for identification.

That is, since the waveform input to the identification circuit 4 is a rectangular waveform with no noise as shown in FIG. Dots from 2 to E.

Since the eye pattern does not become narrower even when moving to the 0 point, and there is no noise, even if alignment jitter accumulates due to multiple repeat transmission, there will be no adverse effect on the bit error rate characteristics.

〔Effect of the invention〕

As explained in detail above, according to the present invention, when transmitting repeater monitoring information to a terminal station, identification is performed using a phase-modulated clock signal, and when alignment jitter accumulates due to multiple repeat transmissions. This also has the effect of eliminating any negative effects on the bit error rate characteristics.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the embodiment of the present invention, Fig. 2 is a time chart of waveforms of each part in Fig. 1, Fig. 3 is a block diagram of a conventional example, and Fig. 4 is a waveform diagram of each part of Fig. 3. This is a time chart. In the figure, 1.4 is an identification circuit, 2 is a timing circuit, and 3 is a phase modulation circuit. Kohatsurou's Yase jtsu 70 tsu 20 Tei 1 Kuchihitsu 1 mon each timbre of 5 timchi V-) - Kaya 2 En

Claims (1)

[Claims] In an in-service monitoring method in which repeater monitoring information is transmitted to a terminal station by phase modulation of a main transmission clock signal, a second identification circuit (4) is provided on the output side of the repeater internal identification circuit (1).
), and the clock signal input to the second identification circuit (4) is subjected to phase modulation (3).