JPS5954344A - Timing reproducer - Google Patents

Abstract

PURPOSE:To attain timing reproduction from an NRZ code with a simple constitution, by providing the 1st and the 2nd pulse generating circuits comprising an AND circuit, delay circuit and an NOT circuit, and a circuit picking up an NOR output of the AND circuit so as to eliminate malfunction. CONSTITUTION:The 1st pulse generating circuit 20 comprises an AND circuit 11, a delay circuit 13 giving a delay to its output by a 1/2-bit length of a receiving signal, and an NOT circuit 17 inverting its output and applying the result to other input of the AND circuit 11. The 2nd pulse generating circuit 21 comprises an AND circuit 12 taking an input signal inverted at an NOT circuit 16 as one input, a delay circuit 14 giving a delay to its output by a 1/2-bit length of a receiving signal, and an NOT circuit 18 inverting its output and applying the result to the other input of an AND circuit 12. Further, the NOR circuit of the AND circuits 11, 12 is picked up at an NOR circuit 15.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a timing recovery device for recovering timing from a NIIZ code in self-synchronous baseband data transmission.

Prior Art and Problems RZ (
Return to Zero) coding system and NRZ
(Non Return to Zero) encoding system is known, but the latter has a simpler configuration of the encoding circuit and decoding circuit than the former, and the data transmission speed is approximately twice as high using the same transmitting and receiving elements. Because it can be achieved,
It has been particularly praised for its high-speed data transmission. However, since no change point appears in the baseband signal when consecutive 1'' or θ'' are included, the timing regeneration device has a more complex configuration than a similar device in the RZ coding system, and also has problems in terms of accuracy. .

For example, as shown in FIG. 1, there is a one-shot multivibrator 1 that receives an NRZ code and generates a positive polarity signal e1 synchronized with the signal, and a one-shot multivibrator that also receives an NRZ code and generates a negative polarity signal C2. A shot multivibrator 2 and an OR circuit inputting the signal C1,
An AND circuit 6 is provided which receives the output of this OR circuit B via a one-shot multivibrator 4.5 as one input and the signal e2 as the other input, and is configured to obtain the output from the bit timing OR circuit B. A timing regenerator is known (Japanese Unexamined Patent Publication No. 52-95106).However, the circuit configuration is still complicated because it requires as many as four one-shot multivibrators, and the one-shot multivibrator is weak against noise due to its wooden structure. Because it uses a Schott multivibrator, it has the disadvantage of being prone to malfunction.In other words, data transmitting/receiving circuits are generally susceptible to the intrusion of noise related to transmission lines, and the input is subject to instantaneous signals (whisker-like noise). etc.], which triggers the one-shot multivibrator and causes it to malfunction.

OBJECTS OF THE INVENTION An object of the present invention is to provide a timing recovery device that eliminates such malfunctions and can recover timing from NIIZ codes with a simpler circuit configuration. Below, two examples will be described in detail.

Embodiment of the invention FIG. 2 is a block diagram of the main parts of an apparatus according to an embodiment of the invention.
10 is an input terminal to which the NRZ code signal is applied.

11.12 is an AND circuit, 13.14 is a delay circuit, 15
is a NOR circuit, 16 to 18 are negative circuits, 19 is an output terminal,
20 is a first pulse generating circuit, and 21 is a second pulse generating circuit.

As shown in the figure, the timing regeneration device of this embodiment has the following features:
An AND circuit 11 which takes the input signal as one input, a delay circuit 16 which delays the output of the AND circuit 11 by 1/2 bit length of the received signal, and the output is inverted and applied to the other input of the AND circuit 11. a first pulse generating circuit 20 consisting of a NOT circuit 17; an AND circuit 12 which uses the input signal inverted by the NOT circuit 16 as one input; A second pulse generating circuit 21 consisting of a delay circuit 14 that delays by a long time, and a negative circuit 18 that inverts its output and applies it to the other input of the AND circuit 12, as well as the a) outputs of the AND circuits 11 and 12. A NOR circuit 15 is provided.

FIG. 6 is a diagram showing an example of signal waveforms at various parts when the second illustrated apparatus is operated. The operation of the second illustrated apparatus will be described below with reference to the same figure.

Assuming that the human power α is 0" at the beginning, the output of the delay circuit 13 is "0", and the output of the NOT circuit 17 and therefore the other input of the AND circuit 11 is "1". In this state, the human power σ When becomes 1", the output of the AND circuit 11 becomes 1", and this output 2 is delayed for a certain period of time by the delay circuit 13, inverted by the NOT circuit 17, and added to one input of the AND circuit 11. , the output of the AND circuit 11 becomes "O", and the input of the delay circuit 13 becomes "O" again.
becomes. Therefore, after a certain time delay, the AND circuit 11
In this way, the feedback loop consisting of the antenna circuit 11, the delay circuit 13, and the negative circuit 17 generates the first pulse with a period twice the delay time of the delay circuit 13. It operates as the circuit 20, and this operation continues until the input α becomes "0".

On the other hand, while the input α is “1”, the output slave of the NOT circuit 1B is
Since the human power on the other side of the C an1 circuit 12 is O", the second pulse generating circuit 24 does not generate the 77-1 pulse. However, when the human power a becomes "0", the negative circuit 1B Since the other input of the AND circuit 12 becomes 1'' through 21 is operating, the input a is "O", and the first pulse generating circuit 20 does not generate pulses during that time.

Pulse output C obtained from the first pulse generation circuit 20 and pulse output C obtained from the second pulse generation circuit 21
is added to the NOR circuit 15, and the timing is determined by the falling edge of the output of this NOR circuit 15. As the delay circuits 13 and 14, for example, a lumped constant delay element called a delay line module using a ceramic microchip capacitor and a ferrite core can be used, and the delay time can be varied. By using , it becomes possible to easily deal with changes in transmission speed.

FIG. 4 is a block diagram of main parts representing another embodiment of the present invention, in which the same reference numerals as in FIG. 2 indicate the same parts, and 41 is a control 1
Iris input terminal, 42 is an exclusive OR circuit, 43, 44
is a six-person AND circuit. Depends on the characteristics of the receiver etc.
When the human input signal is distorted, the signal C may become distorted in such a direction that the pulse width of "1" is widened, or conversely, it may become distorted in the direction that the pulse width of "1" is narrowed. For example, when driving a switching element whose rising characteristic is inferior to its rising characteristic with an NRZ code as shown in Fig. 5 (A), the output of the switching element is as shown in Fig. 5(A).
The signal obtained by binarizing this signal using a threshold value of 5D has a widened pulse width of "1" as shown in FIG. 3(C). In this embodiment, accurate timing reproduction is performed even if there is some distortion in such a case, and the AND circuits 11 and 12 in FIG. 2 are replaced with AND circuits 45 and 44 operated by five people. An exclusive OR circuit 42 which replaces the output of the NOT circuit 17 with the input of the AND circuit 44 and the output of the NOT circuit 18 with the input of the AND circuit 46, and calculates the exclusive OR of the input a and the control signal y. is provided so that the upward direction can be reversed by switching the ``ifi'' control signal ``da'' to ``1'' and ``0''.

For example, if the input α is subject to distortion in which the pulse width of 1" always tends to narrow, the control signal y is set to 0". FIG. 6 is a diagram showing an example of the signal waveform of each part of the device shown in FIG. The AND circuit 44 of the pulse generating circuit 21 outputs the output of the NOT circuit 17 of the pulse generating circuit 2o of 9L1.
Since the output pulses 61 and 62 of the second pulse generating circuit 21 are generated in synchronization with the normal waveform (indicated by the dotted line) of the human power a, the output pulses 61 and 62 of the second pulse generation circuit 21 are generated in synchronization with the normal waveform (shown by the dotted line) of the human power a.

In addition, when the human power a is subjected to distortion in which the pulse width of "1" always tends to widen, the control i +++ +; r number 1 is changed to °゛1''
It is only necessary to invert the input a and shift the processing. FIG. 7 is a diagram showing an example of the (I) shape of each part of the device shown in FIG. 4 at this time.
By inverting , the output of AND circuit 4 is as follows:
Even if it becomes ``, the blade of negative circuit 1B becomes 1''t.''
1'' (= does not hold), the signal is generated in synchronization with the normal waveform (shown by the dotted line) of the output cackle waves 0, 7i & 18b jα of the first no-response generating circuit 20.

In a system where the human power a is subject to distortion where the response width always tends to narrow (A), the exclusive OR circuit 42 may be omitted.Also, the distortion force of the input a.

Even if the pulse width of "1" appears both in the narrowing direction and in the widening direction, the configuration in which the exclusive OR circuit 42 with the control signal DA set to 0' in FIG. 4 is omitted is used. The signal waveforms of each part of the father are generated in correct synchronization with the normal waveform of α, which is affected by distortion, as shown in FIG. , 11, when the pulse width of "1" is widened, the AND circuits 43 and 44 generate a force that is narrower than the normal width b) Two-whisker-like minute signal components 82 may appear.When such a component 82 is negative, a filter to remove such components 82 should be provided at the subsequent stage of the NOR circuit 15. At this time, the fall of the output d of the NOR circuit 15 is equal to r4 of the bit of the human power α.

As explained in detail about the invention (2. According to the present invention (2), it is possible to extract a timing signal from an NRZ code with high precision using only two delay circuits and a small number of gates, and it is susceptible to noise. Since a one-shot multivibrator is not used, there is no risk of malfunction even if the human signal contains whisker-like noise. A configuration in which the output of the second negative circuit is fed back to the AND circuit, and the output of the second negative circuit is fed back to the first AND circuit (According to 2, there is an advantage that the timing can be reproduced without being affected by some distortion due to human input. .

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional timing regeneration device;
Figures 1 and 4 are main block diagrams showing different embodiments of the present invention. FIG. 3 is a diagram for explaining the operation of the second illustrated device, and FIGS. 5 to 8 are diagrams for explaining the operation of the fourth illustrated device. 10 is an input terminal to which one input word of the NRZ code is added; 11
．． 12 is an AND circuit, 15 and 14 are delay circuits, 15 is a NOR circuit, 16 to 18 are NOT circuits, 19 is an output terminal, 2
0 is a first pulse generation circuit, 21 is a second pulse generation circuit, 41 is a control signal input terminal, 42 is an exclusive OR circuit, and 43 and 44 are six-manufactured AND circuits. Patent applicant: Fuji Electric Manufacturing Co., Ltd. (1 other person)

Claims (1)

[Claims] (1) Input of NRZ code (with t6 in the method of regenerating the timing from No. 4, a first AND circuit to which the 1\IJ input signal is applied to the first input terminal and a second circuit that delays the output of the AND circuit by a predetermined time) a first pulse generating circuit comprising a first delay circuit and a first negative circuit which inverts the output of the delay circuit and applies it to a second input terminal f of the first AND circuit; a second AND circuit that is applied to the first input terminal; a second delay circuit that delays the output of the AND circuit for a predetermined time; and a second delay circuit that inverts the output of the delay circuit and connects it to the second input terminal of the second AND circuit. a second pulse generating circuit comprising a second inverting circuit and a second negative circuit; a gate for combining the outputs of the second pulse generating circuit and the first pulse generating circuit and outputting term f minc No. 13; ('l) In a method of reproducing timing from an input signal of an NRZ code, a first AND circuit to which a J group human input signal is applied to a first input terminal and the output of the AND circuit are delayed by a predetermined time. 7.) a first pulse generating circuit comprising a first delay circuit and a first NOT circuit which inverts the output of the delay circuit and applies it to the second input terminal of the first AND circuit; a second AND circuit whose inverted signal is applied to the first input terminal; a second AND circuit which delays the output of the AND circuit by a predetermined time; and a second AND circuit which delays the output of the AND circuit by a predetermined time;
The second human power η of the second AND circuit; 1. The second Banotos light-generating circuit consisting of the second -r foot circuit added to the first child, and the second and previous g122'B1 pulse generation circuits. The outputs of the first negative circuit are combined to output the dimming frj signal -(-, and the 14i power of the first negative circuit is expressed as the ')L
2 of the AND circuit, input the 5th input 0iii, and
1. A timing reproducing device characterized in that the output of the second occupancy circuit is manually inputted to the sixth manually-powered ailW child of the Wl'l1 add circuit. (In a method for regenerating timing from an input signal of a 51NRZ code, a means for inverting the nfS signal, a first AND circuit to which the inverted input signal is applied to a first input terminal, and an output of the AND circuit for a predetermined period of time. a first delay circuit that delays the delay; and a first NOT circuit that inverts the output of the delay circuit and applies it to the second input terminal of the first AND circuit.
a second AND circuit which applies a signal obtained by further inverting the inverted input signal to a first input terminal; a second delay circuit which delays the output of the AND circuit for a predetermined time; and a second delay circuit which inverts the output of the delay circuit. and a second NOT circuit which is applied to the second input terminal of the $2 AND circuit, and the outputs of the second and first pulse generating circuits are combined to generate a timing signal. The output of the first NOT circuit is input to the sixth input terminal of the second AND circuit, and the output of the second NOT circuit is input to the third input terminal of the first AND circuit. What is claimed is: 1. A timing reproducing device characterized by having a configuration in which input is input to an input terminal of the timing reproducing device.