JPS59193656A - Burst signal receiver - Google Patents

Abstract

PURPOSE:To detect easily collision of signals by applying partial response conversion to a receiving signal, converting the result into an AC signal and performing signal identification by means of a binary identification device at the latter half code time corresponding to the Manchester code converted into two codes. CONSTITUTION:A transmission signal A inputted to a terminal 11 of an optical burst signal transmitter 10 is subject to the Manchester code conversion 14 by a clock signal f0, electrooptic-converted 15 via an enable signal 13 and transmitted as an optical signal 6. On the other hand, the signal 6 is photo-electric- converted 2 at an optical burst signal receiver 20, is subject to partial response code conversion 21 and an output D not including a DC component is amplified 3' in terms of AC. Nonlinear extraction is attained from the output at a timing extraction circuit 22, and signal identification is performed for a binary identification device 4 at the latter half code time corresponding to the Manchester code converted into the two codes by an output signal I of a 1/2-frequency division circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiving device suitable for receiving intensity-modulated burst signals, particularly optical burst signals.

<Prior Art> A conventional receiving apparatus for receiving an optical burst signal subjected to intensity modulation was constructed as shown in FIG. That is, the received optical burst signal 1 is converted into electricity by a photoelectric conversion circuit 2, and the electrical signal is amplified by an amplifier circuit 3, then identified by an identification circuit 4, and outputted to a received signal output terminal 5.

FIG. 2 shows signal waveforms at each part of FIG. 1. 2A shows the optical input signal 1, FIG. 2B shows the output when the amplifier circuit 3 is of the DC amplification type, and FIG. 2C shows the output when the amplifier circuit 3 is of the AC amplification type. As shown in FIG. 2A, since the received optical burst signal 1 is optical intensity modulated, there is no negative component in the signal.

Therefore, as shown in FIG. 2B, when using the amplifier circuit 3 that can amplify up to DC, there is no fluctuation in the DC level of the input signal to the discrimination circuit 4. Therefore, the optimum discrimination level of the discrimination circuit 4 is as shown by the dotted line ZS+. However, since the amplifier circuit 3 requires high gain and wideband amplification, it is actually difficult to use DC amplification, so an AC amplifier circuit is used. In this case, the output of the AC amplifier circuit is
As shown in Figure C, a transient response occurs due to DC interruption to the optical input burst signal, and the optimum discrimination level of the discrimination circuit 4 changes as shown by the dotted line tS2.33 The discrimination level of the normal discrimination circuit 4 is fixed. and in steady state 41
However, this level approaches the zero level, which has the disadvantage that the beginning part of the burst signal cannot be correctly identified. In order to reduce this transient response time region, there is a method of increasing the cutoff frequency of the AC amplifier circuit 3, but increasing the cutoff frequency causes waveform distortion in the output of the amplifier circuit 3 in a steady state. This has the disadvantage that the eye pattern deteriorates and identification errors increase.

On the other hand, when optical signals are simultaneously received from two or more locations (collision of optical signals), if there is a level difference of more than a certain level between the optical signals, an error in identifying the digital signal will not occur.

Although this is an advantage of digital signal transmission, it is not possible to obtain information on signal collisions, and the C8MA/CD method, which is one of the packet transmission procedures [References R, M, M, etCa]
lfe and 1)-R, BOggS+” Ethe
rnet: Distributed Packet
Switchingfor I,ocal Comp
uter Networks”, Communic
ations of the ACM, Vol. 19
, no, 7. July 1976:] was not applicable. In other words, if the signal collision force becomes too strong, for example, the optical transmission from all the transmitting sources is stopped and the transmission is restarted after a different appropriate time, but the function of one transmitting source deteriorates and the transmitting output decreases. If the level is low, signal collision will not be detected as described above, and the information from the transmitter whose level has decreased will not be received by the receiving device.

<Summary of the Invention> A first object of the present invention is to provide a burst signal receiving device that uses an AC amplifier circuit, has a short transient response time in burst signal reception, and is capable of binary discrimination.

A second object of the present invention is to provide a burst signal receiving device that can detect signal collisions with a relatively simple configuration.

According to the present invention, in a device for receiving a burst signal intensity-modulated by a Manchester code, that is, a dipulse code signal, by passing the received signal through a partial response conversion PR (1, -1) (bipolar conversion) circuit, This AC signal is converted into an AC signal, and this AC signal is processed by a binary discriminator at the latter code time corresponding to the Manchester code converted into a binary code, and the output is used as a burst signal receiving device; a fir output.

Furthermore, the discrimination level of the binary discriminator is slightly shifted from zero, and discrimination is performed for each input code time,
A transition rule violation in the identified code string is detected by a transition rule violation detection circuit, and the detection output is detected as an abnormality in the burst signal, such as a signal collision or a synchronization abnormality. In other words, a ternary eye pattern is generated by the partial response conversion at every second No. 71 time in the first half corresponding to the Manchester code converted to a two-line code, and when a small level signal collides with a large level signal, the above-mentioned 3. The level of the direct Ainokuhn part is relatively greatly affected, and the binary identification of this part results in a transition rule violation, making it possible to detect the transition rule violation with one binary classifier. As can be understood from the above explanation, the premise of the receiving device of the present invention is that on the transmitting side, transmission data is converted into Manchester code, and the Manchester code data is used to intensity modulate a carrier wave such as light or radio wave.
Send as a strike signal.

<First example> FIG. 3 shows an example in which the present invention is applied to an optical communication system.

The transmission signal A (for example, the fourth fdA) input to the transmission data input terminal 11 of the optical burst signal transmitter 10 is input to the Manchester code conversion circuit 14.

A clock signal (fo) synchronized with the transmission signal A also enters the Manchester code conversion circuit 14 from the cross input terminal 12. As shown in FIG. 5, this Manchester code conversion rule gives a conversion output of "10" for an input of 0"'.

The conversion output for the input "1" is P01"'.The human power B of the transmittable input terminal 13 is at time t1 as shown in FIG. 4B.
When it rises up, the output C of the Manchester code conversion circuit 14
The signal (FIG. 4C) becomes a burst signal, undergoes optical intensity IW modulation in the electrical/optical conversion circuit 15, becomes an optical signal 6, and is sent out from the optical burst signal transmitter 10.

This optical signal 6 is converted into electricity by the optical-to-electrical conversion circuit 2 of the optical burst signal receiver 20 to which the present invention is applied.

The electrical signal output is converted into a signal from which the direct current component has been removed, as shown in the fourth diagram, by a universal response sign conversion circuit 21. This conversion rule is shown in Figure 5.
1 “1゜-1” for “input”, “o” for “0” input
, o''.The partial response code conversion circuit 21' is composed of an analog circuit, which delays the input by one bit and inverts the polarity.
It has a function of adding inputs with no delay, and exhibits a type of single-wave characteristic that removes DC components. With such a configuration, for example, an input of "10" will be converted to "1.-1" and "00", but since the second half -1" and the first half "0" overlap, it will be converted to "1-10". In the case of continuous takes, "1" at the first time of this conversion output is a value X that depends on the previous sign.Now, the output that depends on the previous sign is X, and the positive amplitude is When the output is shown as + and the negative amplitude output is shown as -, the code "1010' becomes "x-+" as shown in FIG.
-". The output waveform corresponding to this is the one corresponding to the column of the cover pattern input to the discriminator in FIG.

In this way, partial response conversion is a type of bipolar conversion, and since there is no DC component even if the signal subjected to partial response conversion is amplified by the AC amplifier 31, it is possible to achieve the optimal discrimination level as shown in Figure 2C. No fluctuations occur. The amplified output signal of this AC amplifier 3' is output to the discriminator 4.
and is input to the timing extraction circuit 22. The timing extraction circuit 22 performs nonlinear extraction (full-wave rectification (FIG. 4E)) to obtain a signal F (FIG. 4F) having a frequency 2fO, which is twice the information transmission lock (fo).
The signal is input to the /2 frequency divider circuit 23 and the carrier detection circuit 24. The carrier detection circuit 24 detects the carrier (input of the optical burst signal receiver) based on the presence or absence of a 2fO component with a frequency twice that of the information transmission lock.

As shown in FIG. 4G, this detection output G rises from point 15j at point t1 with a delay of >91 minutes by half a cycle of clock F, and enters the monostable multi-bi break 25. The output H (H in FIG. 4) of the monostable multivibrator 25 is input to the synchronization/% turn detection circuit 26.

On the other hand, the output (1) of the 1/2 frequency divider circuit 23 (FIG. 4 1) has the same frequency as the information transmission lock (fO), and the same pattern detection circuit 26, clock output terminal 27 and discriminator 4
Output to. The discriminator 4 discriminates the output of the AC amplifier 3' by the clock of the 1/2 frequency divider circuit 23, and the
The identification output J of the N RZ code shown in is the received signal output terminal 5.
and the synchronization pattern detection circuit 26. The synchronization pattern detection circuit 26 detects a carrier for a certain period of time (time T1 when the output H of the monostable multivibrator 25 is at a high level).
), performs synchronization detection operation. At the rising edge of the tb clock query, the identification output J is sampled and the 1/2 frequency divider circuit 23 is reset until 0 is sampled. This time T1 is selected to be less than or equal to the preamble time of the normal transmission signal. If a specific synchronization turn is not obtained at the output J of the discriminator 4 (the example in FIG. 4 shows an alternating pattern of 1 and O) within this time, the synchronization pattern detection circuit 26 outputs K.
(K in FIG. 4) is output, and by inverting the output of the 1/2 frequency divider circuit 23, the synchronization pull-in is performed. O is detected at time t3 and a synchronized state is achieved.

After this synchronized pull-in, the eye: / / turn (example passed through a 72 MHz low-frequency p-wave generator) has a wink pattern in which the first half is 3 values and the second half is binary, and when identified in the second half, it becomes a 2-value wink pattern. Deterioration in value identification and identification can be reduced,
In addition, the discriminator 4 can be a simple binary discriminator circuit.

Second Embodiment> FIG. 7 shows the AC amplifier 3'' in the embodiment shown in FIG.
This is an embodiment in which an optical burst signal collision detection function is added to the optical burst signal receiving apparatus by changing the following, and parts corresponding to those in FIG. 3 are given the same reference numerals. Further, FIG. 8 shows an example of the operation waveforms of each part in FIG. 7, and parts corresponding to those in FIG. 4 are given the same reference numerals.

The operation is the same until an output is obtained from the AC amplifier 31 in FIG. If the outputs of the AC amplifier 3' are D1 and D2 in FIG. 8, respectively, when the signal arrives (optical signal collision), the input to the input terminal 30 in FIG. Extraction circuit 22
is input.

The timing extraction circuit 22 outputs a signal F having twice the frequency (2fo) of the information transmission lock in the same manner as described above. This signal F is passed through the OR circuit 36 to the divide-by-7 circuit 23.
It becomes an information transmission lock (■) at the frequency fO.

The input signal D1+D2 is discriminated by the discriminator 4 using the signal F, and the discrimination output is inputted to the shift register 31. The shift register 31 stores three codes of signals identified at 2fO cycles as a signal F. When the output of the first stage of the shift register 31 is ANDed with the output information transmission lock query of the 1/2 frequency divider circuit 23 and the AND circuit 33, reproduced data J is output as a 9R'Z code to the received signal output terminal 5. .

The combinations of three identification codes obtained at each stage of the three-stage shift register 31 are shown in the identification output column in FIG. FIG. 5 shows two types in which the threshold level of the discriminator 4 deviates from O by +Δ or -Δ as shown in FIG.

In FIG. 5, the transition rule violation column shows transition rule violations for the corresponding identification output code. That is, for example, the correct identification code "0"
There is no sign change such that 10'' becomes uooo'', and a pattern in which the second bit of these three bits becomes O is inevitable. Similarly, any change in the sign of the second bit in the 3-bit identification output shown in FIG. 5 violates the transition rule. Using this transition rule violation, signal collision can be detected in case of synchronization error or reception of the information transmission lock (FO).

The examples in FIGS. 7 and 8 show a case where the discrimination output L is the threshold value of the discriminator 4, and the transition rule violation detection circuit 32 detects that the 3-bit input from the shift register 31 is 6000", "0".
01", '1oo"u111", and outputs it. At time t4 in FIG. 8, the 3-bit input pattern iL of the transition rule violation detection circuit 32 becomes " 111, the transition rule violation detection circuit 32 outputs an output by matching the transition rule violation pattern shown in FIG. An output M is output to the controller 11 for detecting a collision (transition rule violation).

On the other hand, the carrier detection circuit 24 and monostable multivibrator 25 operate in the same manner as explained in FIG. 3, and generate gate information H for performing a synchronous pull-in operation for a certain period of time after carrier detection. This signal H and the collision (transition rule violation) detection output M are input to the AND circuit 35, and the output thereof is input to the 1/2 frequency divider circuit 23 through the OR circuit 36, and the 2fO clock pulse F is decreased by one. A synchronous pull-in is performed. That is, one pulse is subtracted by inserting one pulse between two pulses and converting them into one pulse with a longer width.

If a violation of the transition rule occurs even after synchronization pull-in, as at time t5t6t7... in FIG. can be used as a collision detection signal. In this case as well, as shown in the explanation of FIG. 3, errors are unlikely to occur in the received signal output J. Furthermore, as shown in FIGS. 5 and 6, violations of the transition rule tend to occur in the first half of the wink pattern (ternary eye pattern). Therefore, by reducing the threshold value Δ, it becomes easier to receive interference waves (coding collisions), and it becomes possible to detect interference waves (collisions) with a small level. ′
:1: Since the received signal is generated in the latter half of the wink pattern (binary eye pattern), it is less susceptible to interference waves. Since the threshold value is small, Umabetsukan, 4, used in the first half and second half of Wink Patare can be used in common.

Effects> As explained above, according to the present invention, an AC amplifier can be used in the burst receiving device, the transient response time to the burst signal is short, low level 1M collision detection is possible, and identification deterioration of the received signal is prevented. There are advantages such as the fact that the transition law Jfj is small, and the information transmission lock erroneous synchronization signal can be obtained from the transition law Jfj; Furthermore, the device of the present invention requires fewer additional circuits than conventional circuits.These features make it suitable for high-speed packet transmission receiving devices, C8
It can also be applied to an MA/CD type receiving device. It is clear that ζ shown for an optical burst signal receiver can also be applied to a burst signal receiver for a transmission line using a coaxial cable or a pair of wires. However, especially in transmission using optical intensity modulation, the OdB loss of electrical signals on the transmission line is a loss of 20 dB in optical power, so collisions between optical bursts with large level differences are likely to occur. It is particularly suitable for detecting collisions of optical nostrils.

As a method for highly reliable collision detection, 0, 1 is used as the transmission information pattern. At this time, the threshold individual cover turn becomes indeterminate and −〇+ from FIG.
This corresponds to the case where there is no received signal, which corresponds to the case where there is no received signal. Therefore, when detecting a collision based on a violation of the transition law, including when there is no received signal, it is not affected by the noise of the signal that has become zero level due to incompleteness of partial response conversion or cancellation, so when the received signal is zero, other When a small level burst is input, the original collision can be detected and highly reliable information can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional optical burst receiver,
2 is a waveform diagram of each part of the optical burst receiver shown in FIG. 1, FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. 4 is a diagram showing an example of waveforms of each part of FIG. 3. FIG. 5 is a diagram showing various combinations of code conversion used in this invention, FIG. 6 is a diagram showing an eye pattern (wink pattern) of input to a discriminator, and FIG. Block Diagram,
Figure 8 is a diagram showing an example of waveforms at each part of Figure 7. 1: Received light, 2: Photoelectric conversion circuit, 3: Amplification circuit, 4:
Discriminator, 5: Received signal output terminal, 10: Optical burst receiver, 11: Transmission data input terminal, 12: Clock input terminal, 13: Transmission enable input terminal, 14: Manchester code conversion circuit, 15: Electrical/optical conversion Circuit, 20: Optical burst signal receiver, 21: Partial response conversion circuit, 22
: Timing extraction circuit, 23 : 1/2 frequency divider circuit, 2
4: carrier detection circuit, 25: monostable multivibrator, 26 two-synchronization pattern detection circuit, 27: clock output terminal, 3o: input terminal, 31: three-stage shift register, 3
2: Transition law violation detection circuit, 37: Collision (transition rule violation) detection output terminal. . Patent issued and approved by Takashi Kusano, representative of Nippon Kamei Hyōden Telephone Corporation, 30

Claims (1)

[Claims] (1) In a receiving device for a burst signal that has undergone intensity modulation after Manchester code conversion, a partial response conversion circuit that converts the received signal into alternating current by partial response conversion, and the conversion output of the partial response conversion circuit are supplied. A burst signal receiving device, characterized in that it is equipped with a binary discriminator that identifies a signal at a later code time corresponding to a Manchester code converted into a Manchester code, In the signal receiving device, a partial response conversion circuit converts the received signal into alternating current by partial response conversion, the conversion output of the partial response conversion circuit is supplied, and this is converted into Manchester code converted into 2 codes. A binary discriminator that identifies signals at a discrimination level slightly different from zero for each corresponding code time, and a transition rule violation detection circuit that outputs a transition rule violation of the identified code string as a received burst code abnormal output. What is claimed is: 1. A power tip burst signal receiving device comprising: