JPH1155331A - Optical digital signal receiving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To receive plural signals whose transmitting rates are different by a single filter in an optical digital signal receiving device for operating signal reproduction by receiving an optical signal in an NRZ(non-return to zero) system or an RZ(return to zero) system at different transmitting rates, and converting it into an electric signal. SOLUTION: A pulse generating means 1 generates a pulse whose pulse width is the half value of a clock cycle in a signal at the highest rate transmitting rate to be received at the changing point of a converted electric signal. A filter 2 outputs the clock frequency components of a signal at the highest rate transmitting rate included in this generated pulse. A pulse converting means 3 converts a sine wave signal outputted from the filter 2 into a pulse signal. A clock cycle converting means 4 coverts the cycle of the pulse signal outputted from the pulse converting means 3 into the clock cycle of the signal to be reproduced. A signal reproducing means 5 reproduces the converted electric signal based on an output clock signal from the clock frequency converting means 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical digital signal receiving apparatus, and more particularly, to an optical digital signal receiving apparatus which receives NRZ or RZ optical signals having different transmission rates, converts them into electric signals, and reproduces the signals. Related to the device.

[0002] The present invention is directed to an improvement of an optical receiver in an optical digital signal transmission system for transmitting an optical digital signal using an optical fiber.

[0003]

2. Description of the Related Art FIG. 11 shows a unipolar NR as a transmission signal.
FIG. 2 is a diagram illustrating a configuration of a conventional optical digital signal receiving device using a Z (Nonreturn-to-Zero) signal. FIG. 12 is a timing chart showing signal waveforms at various parts of the configuration shown in FIG.

In FIG. 1, an optical digital signal (S1) is input to a light receiving element 101 composed of a photodiode, and the light receiving element 101 converts the signal into an electric signal (S2). The reception amplifier 102 amplifies the electric signal (S2) to a predetermined amplitude, and sends the signal to the identification circuit 103 and the nonlinear circuit 104. The optical digital signal (S1) contains noise, and the signal (S3) sent from the reception amplifier 102 also contains noise. In order to eliminate this, a signal is reproduced in the identification circuit 103.

[0005] The non-linear circuit section 104 includes a reception amplifying section 102.
At the transition point of the signal (S3) sent from the
4) and send it to the filter 105. The filter 105 is a high-Q bandpass filter whose pass band is the clock frequency f ₀ of the transmission signal, and the pulse (S4)
The component of the frequency f ₀ contained in the output as a sine wave (S5). The non-linear circuit section 104 outputs the signal (S
Since the component of the clock frequency f ₀ is not included in 3), a process of generating the component is performed. The timing amplifier 106 converts the sine wave (S5) into a pulse signal (S6). The discrimination circuit 103 is mainly composed of a D-FF (Flip Flo
p), and determines the value “1, 0” of the signal (S3) sent from the reception amplification unit 102 at the rising timing of the pulse signal (S6) to determine the reproduction signal pulse (S
7) is generated and output.

FIG. 13 is a diagram showing a configuration of a conventional optical digital signal receiving apparatus using a unipolar RZ (Return-to-Zero) signal as a transmission signal. FIG.
4 is a timing chart showing signal waveforms at various parts of the configuration shown in FIG.

The configuration shown in FIG. 13 is basically the same as the configuration shown in FIG. 11, so that the same components are denoted by the same reference numerals and description thereof will be omitted. In the configuration shown in FIG. 13, the point that the non-linear circuit section 104 is removed is the same as FIG.
1 is different from that of FIG.

The optical digital signal (S11) has a pulse width
The RZ signal has an occupancy of 50%. Therefore, reception amplification
The signal (S13) sent from the unit 102 has a clock frequency
Number f ₀Is contained. Therefore, the filter 105
Directly from the signal (S13)₀Take out the ingredients of
The sine wave (S14) is output. That
Other operations are the same as those of the configuration shown in FIG.

[0009]

However, there is no problem if such a conventional optical digital signal receiving apparatus always receives and processes a signal having a single transmission rate. In order to be able to receive and process a plurality of signals different from each other, it becomes necessary to prepare and replace a plurality of filters having different filtering bands. Moreover,
Since a bandpass filter having a high Q is expensive, there is a problem that the product cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and an object of the present invention is to provide an optical digital signal receiving apparatus capable of receiving and processing a plurality of signals having different transmission speeds without changing a single filter. .

[0011]

According to the present invention, there is provided an optical digital signal receiving apparatus as shown in FIG. Although not shown, this apparatus receives a plurality of NRZ optical signals having different transmission speeds and converts them into electric signals. The apparatus includes a pulse generator 1 for generating a pulse having a pulse width of half the clock cycle of a signal having the highest transmission rate to be received at a change point of the converted electric signal; Filter 2 for outputting the clock frequency component of the signal having the highest transmission rate, which is included in the pulse output from, a pulse conversion means 3 for converting a sine wave signal output from filter 2 into a pulse signal, and a pulse conversion means 3 for converting the cycle of the pulse signal output from the clock signal 3 into the clock cycle of the signal to be reproduced, and the reproduction of the converted electric signal based on the clock signal output from the clock cycle conversion means 4. And a signal reproducing means 5 for performing the following.

An optical digital signal receiving apparatus for receiving and processing an RZ optical signal having a pulse width occupation ratio of 50% has basically the same configuration as that shown in FIG. Absent.

First, ITU (International Telecommuni
The transmission speed of optical communication specified by cation union is 5
1.84Mb / s, 155.52Mb / s, 622.08Mb / s, 51.84Mb / s
155.52 Mb / s is 3 times, and 622.08 Mb / s is 12 times. Focusing on such a relationship, the present invention enables reception processing to be performed even when a plurality of optical signals having different transmission speeds are received by a receiver configured with a single filter.

That is, in the configuration shown in FIG. 1, the pulse generating means 1 generates a pulse of a predetermined width at each change point of the electric signal after conversion from the optical signal. This predetermined width is set to a value that is half the clock cycle of the signal having the highest transmission rate to be received. Since such a pulse contains a clock frequency component of the signal having the highest transmission rate, the filter 2 extracts this component as a sine wave signal. Then, the pulse conversion means 3 converts the sine wave signal into a pulse signal.

Next, the clock cycle converter 4 converts the cycle of the pulse signal output from the pulse converter 3 into the clock cycle of the signal to be reproduced. In particular,
Perform frequency division. That is, as described above, since the other transmission speeds have a relationship of 3 times and 12 times the lowest transmission speed, the clock period of the other transmission speed is higher than the clock period of the signal of the highest transmission speed. , 4 times, 12 times, etc. Therefore, the clock cycle converter 4 divides the pulse signal output from the pulse converter 3 to obtain a clock signal having a clock cycle of a signal to be reproduced. Using the clock signal thus obtained, the signal reproducing means 5
Performs signal reproduction of the converted electric signal.

In an optical digital signal receiving apparatus for receiving and processing an RZ optical signal having a pulse width occupation ratio of 50%,
Since the electric signal converted from the optical signal includes the clock frequency component of the signal having the highest transmission rate, the pulse generating means 1 having the configuration shown in FIG. 1 is not required. The other operations except for this point are the same as those of the optical digital signal receiving apparatus of the NRZ system.

Thus, a plurality of signals having different transmission speeds can be received and processed with the single filter 2.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. First, the principle configuration of the first embodiment will be described with reference to FIG. The first embodiment relates to an optical digital signal receiving apparatus of the NRZ system. At a change point of a converted electric signal, a pulse having a pulse width of a half value of a clock cycle in a signal of the highest transmission rate to be received is used. , A filter 2 for outputting the clock frequency component of the signal having the highest transmission rate included in the pulse output from the pulse generating means 1, and a sine wave signal output from the filter 2 as a pulse. Pulse conversion means 3 for converting the signal into a signal, clock cycle conversion means 4 for converting the cycle of the pulse signal output from the pulse conversion means 3 into a clock cycle of a signal to be reproduced,
A signal reproducing means for reproducing the converted electric signal based on the output clock signal from the clock cycle converting means.

First, ITU (International Telecommuni
The transmission speed of optical communication specified by cation union is 5
1.84Mb / s, 155.52Mb / s, 622.08Mb / s, 51.84Mb / s
155.52 Mb / s is 3 times, and 622.08 Mb / s is 12 times. Focusing on such a relationship, the present invention enables reception processing to be performed even when a plurality of optical signals having different transmission speeds are received by a receiver configured with a single filter.

That is, in the configuration shown in FIG. 1, the pulse generating means 1 generates a pulse of a predetermined width at each change point of the electric signal after conversion from the optical signal. This predetermined width is set to a value that is half the clock cycle of the signal having the highest transmission rate to be received. Since such a pulse contains a clock frequency component of the signal having the highest transmission rate, the filter 2 extracts this component as a sine wave signal. Then, the pulse conversion means 3 converts the sine wave signal into a pulse signal.

Next, the clock cycle converter 4 converts the cycle of the pulse signal output from the pulse converter 3 into the clock cycle of the signal to be reproduced. In particular,
Perform frequency division. That is, as described above, since the other transmission speeds have a relationship of 3 times and 12 times the lowest transmission speed, the clock period of the other transmission speed is higher than the clock period of the signal of the highest transmission speed. , 4 times, 12 times, etc. Therefore, the clock cycle converter 4 divides the pulse signal output from the pulse converter 3 to obtain a clock signal having a clock cycle of a signal to be reproduced. Using the clock signal thus obtained, the signal reproducing means 5
Performs signal reproduction of the converted electric signal.

In an optical digital signal receiver for receiving and processing an RZ optical signal having a pulse width occupation ratio of 50%,
Since the electric signal converted from the optical signal includes the clock frequency component of the signal having the highest transmission rate, the pulse generating means 1 having the configuration shown in FIG. 1 is not required. The other operations except for this point are the same as those of the optical digital signal receiving apparatus of the NRZ system.

Thus, a plurality of signals having different transmission speeds can be received and processed with the single filter 2. FIG. 2 is a block diagram illustrating a specific configuration according to the first embodiment. FIG. 3 is a timing chart showing signal waveforms at various parts of the configuration shown in FIG. Hereinafter, when describing the configuration of the first embodiment shown in FIG. 2, FIG. 3 will be referred to as needed. 1 corresponds to the non-linear circuit section 14 in FIG.
Similarly, the filter 2 is connected to the filter 15, the pulse converter 3 is connected to the timing amplifier 16, and the clock cycle converter 4 is connected to the filter 15.
Is connected to the frequency dividing circuit 17 and the switch 18 by the signal reproducing means 5.
Corresponds to the identification unit 13.

In the configuration shown in FIG. 2, the transmission speed is 51.84 Mb / s.
And an optical signal having a transmission rate of 155.52 Mb / s are input and reception processing is performed. Here the transmission speed 155.
The clock frequency of the light signal of 52Mb / s and f _0.

In the figure, the optical digital signal of the NRZ system is
The light is input to the light receiving element 11 composed of a photodiode, and the light receiving element 11 converts it into an electric signal. The reception amplifier 12 amplifies the electric signal to a predetermined amplitude, and
3 and the non-linear circuit section 14. The optical digital signal contains noise, and in order to remove the noise, the identification unit 13 reproduces the signal from the electric signal (T1) sent from the reception amplification unit 12.

The nonlinear circuit section 14 outputs a pulse (T2) at a change point of the signal (T1) sent from the reception amplification section 12.
And sends it to the filter 15 and the divide-by-3 circuit 17. The pulse width T ₀ of the pulse (T2) is 1 / (2f ₀ )
Is set to As a result, this pulse (T2) contains a component of the clock frequency f ₀ . Note that even if the pulse width T ₀ of the pulse (T2) is slightly deviated from 1 / (2f ₀ ), the pulse (T2) has the clock frequency f _0.
Is contained in a smaller amount. Therefore,
The pulse width T ₀ of the pulse (T2) is not necessarily exactly 1 /
It need not be set to (2f ₀ ). Nonlinear circuit section 14
Will be described with reference to FIG.

FIG. 4A shows the internal configuration of the nonlinear circuit section 14, and FIGS. 4B, 4C, and 4D show the signal waveforms of each section of the nonlinear circuit section 14. The nonlinear circuit section 14
The delay circuit (DL) 14a and the exclusive OR circuit (EX-O
R) 14b, and the delay circuit 14a delays the signal (T1) sent from the reception amplifier 12 by a time T ₀ . Thus, the pulse D (= T2) is generated at the changing point (rising timing and falling timing) of the signal B (= T1).

Returning to FIG. 2, the filter 15 determines the transmission speed.
This is a high-Q bandpass filter having a pass band of the clock frequency f ₀ of the optical signal of 155.52 Mb / s, and the pulse (T2)
The component of the frequency f ₀ contained in the output as a sine wave (T3). The timing amplifying unit 16 converts the sine wave (T3) into a pulse signal (T4) and sends it to the divide-by-3 circuit 17 and the switch 18.

[0029] FIG. 5 is a graph illustrating the characteristics of filter 15, shows a steep filtering characteristics in the frequency f _0. The divide-by-3 circuit 17 divides the pulse signal (T4) sent from the timing amplifying section 16 by 3 to generate a switch (SW).
18 is output. In this embodiment, the transmission speed is 155.52 M
Since an optical signal of b / s and an optical signal of a transmission rate of 51.84 Mb / s, which is one third of the optical signal, are inputted, the frequency division is performed by three. The divide-by-3 circuit 17 will be described with reference to FIG.

FIG. 6A shows the internal configuration of the divide-by-3 circuit 17, and FIGS. 6B, 6C, 6D, and 6E show the signal waveforms at various parts of the divide-by-3 circuit 17. Is shown. Divide-by-3 circuit 17
Are D-FF (Flip Flop) 17a, 17b, and NAND
It comprises a circuit 17c and an inverter 17d. The pulse (T2) is input to the reset terminals (R) of the D-FFs 17a and 17b, and the pulse signal (T4) is input to the D-FF1.
7a and 17b are input to respective clock terminals (C). Then, the pulse signal (T
5) is output.

Returning to FIG. 2, the switch 18 receives a pulse signal (T4) from the timing amplifier 16 and a pulse signal (T5) from the divide-by-3 circuit 17. Furthermore, from the outside, an optical signal with a transmission rate of 155.52 Mb / s and a transmission rate
An instruction to receive and process the optical signal of 51.84 Mb / s is received manually. When the switch 18 receives a command to receive an optical signal having a transmission rate of 155.52 Mb / s, the switch 18 selects the pulse signal (T4), and selects a transmission rate of 51.8 Mb / s.
When a command to receive a 4 Mb / s optical signal is received, a pulse signal (T 5) is selected and output to the identification unit 13. In the example shown in FIG. 3, an optical signal having a transmission rate of 51.84 Mb / s is received as an electric signal (T1). Naturally, an instruction is received to receive an optical signal having a transmission rate of 51.84 Mb / s. The pulse signal (T5) is output from the frequency dividing circuit 17 to the identification unit 1.
Sent to 3.

The discriminating section 13 is mainly composed of a D-FF, and determines the value "1, 0" of the signal (T1) sent from the receiving amplifying section 12 as the rising timing of the signal (eg, T5) sent from the switch 18. NRZ
A reproduction signal pulse (T6) of the system is generated and output.

The electric signal (T1) has a transmission speed of 15
The operation when an optical signal of 5.52 Mb / s is received and a command is received to receive an optical signal of a transmission rate of 155.52 Mb / s,
This is the same as the conventional device described with reference to FIGS.

Thus, it is possible to receive and process two optical signals having different transmission speeds only by providing the single filter 15. If the frequency dividing circuit 17 further performs frequency division of another frequency dividing ratio, three or more optical signals having different transmission speeds can be received and processed only by providing the single filter 15. It is also possible.

Next, a second embodiment will be described. FIG.
FIG. 3 is a configuration diagram of a second embodiment. The configuration of the second embodiment is basically the same as the configuration of the first embodiment. Therefore, the same parts are denoted by the same reference numerals,
The description is omitted. In the second embodiment, the clock cycle conversion means 4 shown in FIG. 1 corresponds to the divide-by-3 circuit 17, the switch 18, the peak detection circuit 19, and the level determination circuit 20 in FIG.

In the second embodiment, the peak detection circuit 1
9 and the level determination circuit 20 are newly added, and the input of the external command to the switch 18 is eliminated. That is, the sine wave (T
3) is input, and the peak detection circuit 19 outputs a sine wave (T
3) The peak level is detected. Here, the transmission speed 155.
Pulse (T2) when 52Mb / s optical signal is input
Is three times as high as when an optical signal having a transmission speed of 51.84 Mb / s is input. Therefore filter 1
Component of the frequency f ₀ which is input also because increase to 5, also increases the peak level of the sine wave (T3). Based on this level difference, the level determination circuit 20 performs switching control of the switch 18. That is, if the detected peak level is higher than the predetermined value, it is determined that an optical signal having a transmission rate of 155.52 Mb / s is received, and the switch 18 selects the pulse signal (T4). Transmission speed 51.84M if below
b / s optical signal is received and the pulse signal (T
Select 5).

As a result, it becomes possible to automatically perform a receiving process of two optical signals having different transmission speeds. In addition,
In the second embodiment, the sine wave (T3) output from the filter 15 is input to the peak detection circuit 19, but instead, the peak detection circuit 19
Alternatively, the pulse signal (T4) from the timing amplifying unit 16 may be input.

Next, a third embodiment will be described. FIG.
FIG. 9 is a configuration diagram of a third embodiment. The third embodiment is an optical digital signal receiver for receiving and processing an RZ optical signal having a pulse width occupation ratio of 50%. The configuration is basically the same as that of the first embodiment. It is. Therefore, the same portions are denoted by the same reference numerals, and description thereof will be omitted.

In the third embodiment, the non-linear circuit section 14 is omitted and the reset circuit 21
Is newly added, and the identification unit 13 is changed to the identification unit 22. FIG. 9 is a timing chart showing signal waveforms at various parts in the configuration shown in FIG. Hereinafter, in describing the configuration of the third embodiment illustrated in FIG. 8, FIG. 9 will be referred to as appropriate.

With the configuration shown in FIG. 8, the transmission speed is 51.84 Mb / s.
And an optical signal having a transmission rate of 155.52 Mb / s are input and reception processing is performed. Again, the clock frequency of the optical signal transmission rate 155.52 Mb / s and f _0.

In the figure, an RZ optical digital signal having a pulse width occupation ratio of 50% is input to the light receiving element 11, and the light receiving element 11 converts the signal into an electric signal. The reception amplifier 12 amplifies the electric signal to a predetermined amplitude, and sends it to the identification unit 22, the filter 15, and the reset circuit 21. The electric signal (T11) sent from the reception amplification unit 12 is subjected to signal reproduction in the identification unit 22.

Since the electric signal (T11) is an RZ type signal having a pulse width occupation ratio of 50%, the transmission speed
The 51.84 Mb / s optical signal includes a clock frequency f ₀ component of the optical signal having a transmission speed of 155.52 Mb / s. Therefore, in the third embodiment, the nonlinear circuit section 14 becomes unnecessary. The filter 15 is a high-Q bandpass filter having a pass band at the clock frequency f ₀ of the optical signal having a transmission rate of 155.52 Mb / s, and converts a component of the frequency f ₀ included in the electric signal (T11) into a sine wave (T13). ). The timing amplifying unit 16 converts the sine wave (T13) into a pulse signal (T14) and sends it to the divide-by-3 circuit 17 and the switch 18.

The frequency dividing circuit 17 includes a timing amplifying section 16
Divides the pulse signal (T14) sent from by 3 and outputs it to the switch (SW) 18. D-FF of divide-by-3 circuit 17
A reset pulse (T12) is sent from the reset circuit 21 to each of the reset terminals (R) 17a and 17b. The reset circuit 21 generates a reset pulse (T12) at the rising timing of the electric signal (T11). Also in this embodiment, an optical signal having a transmission rate of 155.52 Mb / s and its 1
Since an optical signal with a transmission rate of 51.84Mb / s of / 3 is input,
The division by 3 is performed.

The switch 18 receives a pulse signal (T 14) from the timing amplifier 16 and a pulse signal (T 15) from the divide-by-3 circuit 17. Further, from outside, an optical signal having a transmission rate of 155.52 Mb / s and a transmission rate of 51.84 Mb / s
Of the optical signal to be received. When the switch 18 receives a command to receive an optical signal having a transmission rate of 155.52 Mb / s, the switch 18 selects the pulse signal (T14) and receives a command to receive an optical signal having a transmission rate of 51.84 Mb / s. The pulse signal (T1
5) is selected and output to the identification unit 22. In the example shown in FIG. 9, an optical signal having a transmission rate of 51.84 Mb / s is received as an electric signal (T11). Naturally, an instruction is received to receive an optical signal having a transmission rate of 51.84 Mb / s. Dividing circuit 1
7 sends a pulse signal (T15) to the identification unit 22.

The discrimination section 22 is mainly composed of a D-FF, and determines the value "1, 0" of the signal (T11) sent from the reception amplification section 12 as the rising timing of the signal (eg, T15) sent from the switch 18. And an RZ-type reproduction signal pulse (T1) having a pulse width occupation ratio of 100%.
6) is generated and output. Note that the identification unit 22 includes a delay function, and the signal (T11) is delayed by a predetermined time. Thereby, the signal (T1) shown in FIG.
1) is delayed by a predetermined time, and in fact, the signal (T15)
Can be determined at the rising timing of.

Note that the transmission speed is used as the electric signal (T11).
The operation when the optical signal of 155.52 Mb / s is received and the instruction to receive the optical signal of the transmission rate of 155.52 Mb / s is performed is the same as that of the conventional apparatus described with reference to FIGS. 13 and 14. Will be the same.

As described above, the reception processing of two optical signals having different transmission speeds can be performed only by providing the single filter 15 in this case. Note that the divide-by-3 circuit 17
In this case, if the frequency division is performed at another division ratio, it is possible to receive and process three or more optical signals having different transmission speeds only by providing the single filter 15.

Next, a fourth embodiment will be described. FIG.
0 is a configuration diagram of the fourth embodiment. The configuration of the fourth embodiment is basically the same as the configuration of the third embodiment. Therefore, the same portions are denoted by the same reference numerals, and description thereof will be omitted.

In the fourth embodiment, the peak detection circuit 2
3 and the level determination circuit 24 are newly added, and there is no input of a command to the switch 18 from outside. That is, the sine wave (T13) output from the filter 15 is input to the peak detection circuit 23, and the peak detection circuit 23 detects the peak level of the sine wave (T13). Here, when an optical signal with a transmission rate of 155.52 Mb / s is input, the peak level of the sine wave (T13) output from the filter 15 is determined when an optical signal with a transmission rate of 51.84 Mb / s is input. Increase compared to. Based on this level difference, the level determination circuit 24 controls switching of the switch 18. That is, if the detected peak level is higher than the predetermined value, it is determined that an optical signal having a transmission rate of 155.52 Mb / s is received, and the switch 18 selects the pulse signal (T14).
If it is equal to or less than the predetermined value, it is determined that an optical signal having a transmission speed of 51.84 Mb / s is received, and the pulse signal (T15) is selected.

As a result, it is possible to automatically perform reception processing of two optical signals having different transmission speeds. In addition,
Also in the fourth embodiment, the sine wave (T13) output from the filter 15 is input to the peak detection circuit 23, but instead, the peak detection circuit 2
3, the pulse signal (T1) from the timing amplifying unit 16
4) may be input.

[0051]

As described above, according to the present invention, a single filter outputs a signal of a clock frequency related to a received signal having the highest transmission rate among a plurality of received signals, and the period of the clock frequency signal is changed. The clock cycle conversion means converts the clock cycle of the received signal to be reproduced. Using the clock signal thus obtained, the signal reproducing means
The electric signal converted from the optical signal is reproduced.

Thus, a plurality of signals having different transmission speeds can be received and processed with a single filter.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a block diagram illustrating a specific configuration according to the first embodiment.

FIG. 3 is a timing chart showing signal waveforms at various parts of the configuration shown in FIG. 2;

4A is a diagram illustrating an internal configuration of a non-linear circuit unit, FIG. 4B is a diagram illustrating a waveform of an output signal T1 of a reception amplification unit, and FIG. 4C is a diagram of a waveform of an output signal of a delay circuit; (D) is a diagram showing a waveform of an output signal T2 of the exclusive OR circuit.

FIG. 5 is a diagram illustrating characteristics of a filter.

FIG. 6A is a diagram showing the internal configuration of a divide-by-3 circuit, and FIG. 6B is a diagram showing a pulse signal (T
It is a figure which shows the waveform of 4), (C) is a figure which shows the waveform of the pulse (T2) from a non-linear circuit, (D) is DF.
It is a figure which shows the waveform of the output signal of F (17b), (E)
FIG. 4 is a diagram showing a waveform of an output signal of the inverter.

FIG. 7 is a configuration diagram of a second embodiment.

FIG. 8 is a configuration diagram of a third embodiment.

FIG. 9 is a timing chart showing signal waveforms at various parts in the configuration shown in FIG. 8;

FIG. 10 is a configuration diagram of a fourth embodiment.

FIG. 11 is a diagram showing a configuration of a conventional optical digital signal receiving device using a unipolar NRZ signal as a transmission signal.

FIG. 12 is a timing chart showing signal waveforms at various parts in the configuration shown in FIG. 11;

FIG. 13 is a diagram showing a configuration of a conventional optical digital signal receiving device using a unipolar RZ signal as a transmission signal.

FIG. 14 is a timing chart showing signal waveforms at various parts in the configuration shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 pulse generating means 2 filter 3 pulse converting means 4 clock cycle converting means 5 signal reproducing means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04B 10/04 10/06 H04L 25/03

Claims (6)

[Claims] An optical digital signal receiving apparatus which receives an NRZ optical signal having a different transmission rate, converts the signal into an electric signal, and reproduces the signal, receives the signal at a change point of the converted electric signal from the optical signal. Pulse generating means for generating a pulse having a pulse width of half the value of the clock period in the signal having the highest power transmission rate, included in the pulse output from the pulse generating means,
A filter that outputs a clock frequency component of the signal with the highest transmission rate; a pulse conversion unit that converts a sine wave signal output from the filter into a pulse signal; and a cycle of the pulse signal output from the pulse conversion unit. Clock cycle conversion means for converting the signal into a clock cycle of a signal to be reproduced, and signal reproduction means for performing signal reproduction of the converted electric signal based on an output clock signal from the clock cycle conversion means. An optical digital signal receiving device. 2. An optical digital signal receiving apparatus which receives RZ optical signals having different transmission speeds, converts the optical signals into electric signals, and reproduces the signals, wherein the RZ system having a pulse width occupation ratio of 50% after conversion from the optical signals. A filter that outputs a clock frequency component of a signal having the highest transmission rate to be received, which is included in the electric signal, a pulse conversion unit that converts a sine wave signal output from the filter into a pulse signal, and a pulse conversion unit. Clock cycle conversion means for converting the cycle of the output pulse signal into a clock cycle of a signal to be reproduced, and a signal for reproducing the converted electric signal based on an output clock signal from the clock cycle conversion means. An optical digital signal receiving device, comprising: reproducing means. 3. An optical digital signal receiving apparatus for receiving and converting two optical signals of the NRZ system having a transmission rate of n times into an electric signal and reproducing the signal, wherein the converted optical signal is converted from the optical signal. At the transition point, a pulse generation unit that generates a pulse having a pulse width equal to half the clock cycle of the signal with the higher transmission speed, included in the pulse output from the pulse generation unit,
A filter for outputting a clock frequency component of the signal having the higher transmission speed; a pulse conversion unit for converting a sine wave signal output from the filter into a pulse signal; and a pulse signal output from the pulse conversion unit for n. Frequency dividing means for dividing, a pulse signal from the pulse converting means and a clock signal from the frequency dividing means, a selecting means for selecting and outputting one of them, based on an output clock signal from the selecting means An optical digital signal receiving device, comprising: signal reproducing means for reproducing a signal of the converted electric signal. 4. The method according to claim 1, wherein the selecting unit compares a peak level detected by the peak detecting unit with a predetermined value, and detects a peak level of an output signal from the filter or the pulse converting unit. And comparing and selecting means for selecting a pulse signal from the pulse converting means when the value is larger than a predetermined value, and selecting a clock signal from the frequency dividing means when the value is equal to or less than the predetermined value. The optical digital signal receiving device according to claim 3. 5. An optical digital signal receiving apparatus for receiving two optical signals of the RZ system having a transmission rate of n times and converting them into an electric signal and reproducing the signal, the pulse width converted from the optical signal. A filter for outputting a clock frequency component of a signal having a higher transmission rate, which is included in an RZ-type electric signal having an occupancy of 50%, and a pulse converter for converting a sine wave signal output from the filter into a pulse signal. A frequency dividing means for dividing the pulse signal output from the pulse converting means by n; a selection of receiving and receiving one of the pulse signal from the pulse converting means and the clock signal from the frequency dividing means to select and output one of them; Means for reproducing a signal of the converted electric signal based on an output clock signal from the selecting means. Communication device. 6. The selecting means, comprising: a peak detecting means for detecting a peak level of an output signal from the filter or the pulse converting means; and comparing a peak level detected by the peak detecting means with a predetermined value. And comparing and selecting means for selecting a pulse signal from the pulse converting means when the value is larger than a predetermined value, and selecting a clock signal from the frequency dividing means when the value is equal to or less than the predetermined value. An optical digital signal receiving apparatus according to claim 5.