JP2000004261A - Method and device for transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide transmission equipment capable of multiplex transmission of plural kinds of information with a little delay. SOLUTION: At a transmission terminal 1, a selector 13 multiplexes a command and data inputted through different systems and generates a multiplexed signal sequence. According to predetermined encoding rules, an encoding part 14 generates a multi-level code by determining the amplitude value of a multi- level code this time based on the amplitude value of a multi-level code generated the last time. A transmission part 16 transmits the generated multi-level code sequence 6 through a transmission line 3 to a reception terminal 2. According to predetermined decoding rules, a decoding part 24 at the reception terminal 2 decodes and reproduces the command and data from the amplitude value of the multi-level code sequence 6 outputted from a reception part 21 and the amplitude value of the multi-level code received the last time. The decoding part 24 separately outputs the command and data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a transmission method,
More specifically, the present invention relates to a transmission method in which a multi-level code with good DC balance is transmitted through a transmission path.

[0002]

2. Description of the Related Art In a transmission apparatus, a transmitting end sends data to be transmitted to a receiving end to a transmission line. Further, the transmitting end:
In some cases, a command is sent to the transmission path to instruct the receiving end to execute a predetermined operation. These data and commands may be multiplexed and transmitted as a plurality of types of information as shown in FIG. In the symbol sequence 111 of FIG. 11, COM 112 and COM 113 are respectively
Command symbol. DATA 114 is a data symbol.

When the transmitting end continuously transmits the COM 112 shown in FIG. 11, the average value of the signal fluctuates depending on the characteristics of the transmission path. That is, the transmission path cannot correctly transmit a signal having the same code. Therefore, a transmission line code is adopted for the transmission device. The transmitting end converts a symbol (command or data) in which the same code is excessively continuous into a symbol in which different codes are mixed appropriately in accordance with a predetermined coding rule. By this transmission line coding, a signal with good DC balance is transmitted to the transmission line.

One of the transmission line codings is disclosed in US Pat.
No. 530,088 ". This US patent discloses so-called 4B5B encoding. Less than,
4B5B encoding will be described with reference to FIG.
12 is provided at the transmitting end. The encoding unit 121 includes the DATA 114 and COM of FIG.
112 or COM 113 is input. Data to be transmitted by the transmitting end is generated by being divided into blocks of 4 bits. Therefore, the 4-bit DATA 114
Is represented by one of 16 (= 2 ⁴ ) symbols. Also, the command to be transmitted is COM 112 and C
In the two cases of the OM 113, even if each is divided into blocks each having a length corresponding to 4 bits, only one symbol is represented. In other words, the transmitting end
When 114, COM 112 or COM 113 are summed, 18 symbols are transmitted to the receiving end.

In 4B5B coding, 18 symbols with good DC balance are selected in advance from 32 symbols that can be represented by 5 bits. The selected 5-bit symbol is assigned to the input 4-bit symbol. Thus, the rule of 4B5B encoding is determined.

[0006] As shown in FIG. 13 (a), the encoding unit 121 outputs a 4-bit symbol (COM 112, COM 11).
3 or DATA 114). The encoding unit 121 performs encoding based on the rule of 4B5B encoding, whereby a 4-bit symbol is converted into a 5-bit symbol (shown as Xcode in the figure) 115. The 5-bit symbol 115 is transmitted to the receiving end through the transmission path. At the receiving end, a decoding unit is provided. As shown in FIG.
It waits for the bit symbols 115 to be aligned. The decoding unit performs decoding based on the rule of 4B5B encoding, whereby the 5-bit symbol 115 is restored to the original 4-bit symbol (DATA114 or the like).

As described above, even if a signal sequence with poor DC balance is generated at the transmitting end, a signal sequence with good DC balance is transmitted to the transmission line by employing the transmission line code. Thereby, information can be correctly transmitted between the transmitting end and the receiving end. Further, in 4B5B encoding, a plurality of types of information (typically, commands and data) can be multiplexed.

[0008]

However, in the conventional 4B5B coding, the transmitting end and the receiving end have to wait for 4-bit and 5-bit symbols to be aligned. That is, when encoding and decoding, a transmission delay occurs. For this reason, there is a problem that a data transmission device having a restriction on transmission delay cannot secure a processing time for converting into a signal sequence with good DC balance. In the above-mentioned U.S. Patent, the 4-bit signal sequence is encoded by the encoding unit 1.
21, and a 5-bit signal sequence is output in parallel from the encoding unit 121. However, a serial-parallel conversion is performed before the encoding unit 121. A transmission delay occurs during the serial-parallel conversion. That is, in the conventional transmission path coding, the above-described transmission delay occurs in any part.

Therefore, an object of the present invention is to provide a transmission method and a transmission / reception apparatus capable of transmitting information with a small transmission delay while multiplexing a plurality of types of information.

[0010]

The objects of the present invention can be attained by the following first to fortieth aspects. A first invention is a method of transmitting a multilevel code represented by a plurality of amplitude values from a transmitting end to a receiving end via a transmission path, wherein the transmitting end transmits information to be transmitted to the receiving end in the past. Is generated according to a coding rule determined based on a relationship between the currently generated multi-level code and the currently generated multi-level code to generate a multi-level code sequence. And the receiving end receives the multi-level code sequence through the transmission path and, while obeying the decoding rule corresponding to the coding rule, determines the relationship between the currently received multi-level code and the multi-level code received in the past. , The received multi-level code sequence is decoded to reproduce information.

According to the present invention, the transmitting end encodes information according to the relationship between the past multi-level code and the current multi-level code and transmits the information to the receiving end. That is, the transmitting end is a conventional 4B5B
Information can be encoded without having to wait until a 4-bit block is completely input as in encoding. As a result, at the transmitting end, the processing time from generation of information to be transmitted to completion of encoding is reduced. Further, the receiving end can decode and reproduce information from the transmitting end based on the relationship between the current received multi-level code and the past received multi-level code. That is, the receiving end, like the conventional 4B5B decoding,
The information can be decoded and reproduced without waiting until the 5-bit code string is completely input. Accordingly, at the receiving end, the processing time from the reception of the multi-level code to the end of the decoding is reduced. Thus, according to the transmission method of the present invention, information can be transmitted with a small amount of delay.

Further, according to the present invention, the transmitting end converts transmission information into a multi-level code. Because of this multilevel code,
The relationship between the past multi-level code and the current multi-level code, that is, many patterns of amplitude values can be created. Therefore, patterns of different amplitude values can be assigned to a plurality of types of information. Thus, a plurality of types of information can be multiplexed and transmitted with a small delay amount.

A second invention is dependent on the first invention,
The transmitting end encodes information according to an encoding rule determined based on a relationship between the multi-level code generated immediately before and the currently generated multi-level code. And decoding is performed based on the relationship with the multi-level code received immediately before. According to the first aspect, it is necessary for the transmitting end and the receiving end to hold the amplitude values of the past multilevel code. According to the present invention, since the transmitting end and the receiving end use the amplitude value of the previous multi-level code for encoding and decoding, there is no need to hold a plurality of amplitude values. Thereby, the configuration of the transmitting end and the receiving end can be reduced in size.

A third invention is dependent on the first invention,
The information includes a plurality of types of symbols, and the transmitting end encodes the plurality of types of symbols into a multi-level code having the same pattern according to a coding rule, generates a multi-level code sequence, and generates the generated multi-level code. In the column, due to the phase change of the same pattern,
A change from one symbol to another is represented.
According to the present invention, the transmitting end transmits the change from one symbol to another symbol to the receiving end by changing the phase of the same pattern. Therefore, the receiving end can decode and reproduce another symbol by detecting the change in the phase. This change in phase can be detected based on the past and present amplitude values of the multilevel code, as in the first invention. That is, according to the present invention, similarly to the first invention, information can be multiplexed and transmitted with a small delay amount.

A fourth invention is according to the first invention,
The transmitting end generates a multi-level code sequence in which the same code is not excessively continuous, and transmits the multi-level code sequence to the transmission path. According to the present invention, excessive multi-code sequences do not exist in the multi-level code sequence, so that the DC balance of the multi-level code sequence is improved, and information can be correctly transmitted from the transmitting end to the receiving end.

A fifth invention is dependent on the first invention,
The transmitting end multiplexes a plurality of types of symbols as information,
The multiplexed symbols are encoded according to an encoding rule to generate a multi-level code sequence. According to the present invention, a plurality of types of symbols are multiplexed before encoding is performed. This makes it possible to easily generate a multi-level code sequence in which a plurality of types of symbols are multiplexed.

A sixth invention is according to the first invention,
The transmitting end performs encoding using the maximum and / or minimum amplitude values at least once within a predetermined time interval to generate a multi-level code sequence. In the present invention, the receiving end receives the maximum or minimum amplitude value at a predetermined time. In other words, the receiving end is notified of the maximum amplitude value and the minimum amplitude value of the multi-level code by the transmitting end. This allows the receiving end to:
Each amplitude value of the multi-level code can be identified accurately.

A seventh invention is according to the first invention,
The transmitting end and the receiving end change the encoding rule and the decoding rule as needed. According to the present invention, the encoding rule and the decoding rule are dynamically changed, so that an optimal multi-level code sequence can be transmitted to the transmission path.

An eighth invention is according to the first invention,
The transmitting end encodes a predetermined command as information into a multi-level code sequence, changes the encoding rule based on this command, and the receiving end reproduces the predetermined command and performs To change the decoding rule. According to the present invention, it becomes possible to synchronize the change timings of the encoding rule and the decoding rule based on a predetermined command. As a result, even if these rules are changed, information can be correctly transmitted between the transmitting and receiving ends.

A ninth invention is according to the first invention,
The transmitting end changes the number of amplitude values used for the multi-level code as needed. According to the present invention, the number of the amplitude values is dynamically changed, so that an optimal multi-level code sequence can be transmitted to the transmission path.

A tenth invention is according to the first invention, wherein the transmitting end encodes a predetermined command as information into a multilevel code sequence, and based on the command, an encoding rule, The number of amplitude values used for the multi-level code is changed, and the receiving end reproduces a predetermined command, and changes the decoding rule and the number of amplitude values used for the multi-level code based on the command. According to the present invention, the combination of the encoding rule and the decoding rule and the number of levels used in encoding and decoding are dynamically changed. As a result, a more optimal multi-level code sequence can be transmitted to the transmission path.

An eleventh invention is a method for optically transmitting a multilevel code represented by a plurality of amplitude values from a transmitting end to a receiving end through an optical transmission line, wherein the transmitting end transmits the multi-level code to the receiving end. The power information is coded according to a coding rule determined based on a relationship between a multi-level code generated in the past and a currently generated multi-level code, and a multi-level code sequence is generated. Performs electro-optical conversion on the code string to generate an optical signal,
The generated optical signal is sent to the optical transmission line, and the receiving end performs photoelectric conversion on the optical signal input through the optical transmission line,
A multi-level code string reproduced based on a relationship between a currently reproduced multi-level code and a previously reproduced multi-level code while reproducing a multi-level code string and following a decoding rule corresponding to the encoding rule. And reproduce the information.

A twelfth aspect is according to the eleventh aspect, wherein the transmitting end determines the encoding rule determined based on the relationship between the immediately generated multilevel code and the currently generated multilevel code. , And the receiving end performs decoding based on the relationship between the currently reproduced multi-level code and the multi-level code reproduced immediately before.

A thirteenth invention is according to the eleventh invention, wherein the information includes a plurality of types of symbols, and the transmitting end converts the plurality of types of symbols into a multilevel code having the same pattern according to a coding rule. Encoding to generate a multi-level code sequence,
In the generated multi-level code sequence, a change from one symbol to another symbol is expressed by the phase change of the same pattern.

A fourteenth invention is according to the eleventh invention, wherein the transmitting end generates a multi-level code sequence in which the same code is not excessively continuous, and sends it to the optical transmission line.

A fifteenth invention is according to the eleventh invention, wherein the transmitting end multiplexes a plurality of types of symbols as information, encodes the multiplexed symbols according to a coding rule, and performs multi-level coding. Generate a code string.

A sixteenth invention is according to the eleventh invention, wherein the transmitting end performs encoding using the maximum and / or minimum amplitude value at least once within a predetermined time interval, and performs multi-level coding. Generate a code sequence.

A seventeenth aspect is according to the eleventh aspect, wherein the transmitting end and the receiving end change the encoding rule and the decoding rule as necessary.

An eighteenth invention is according to the eleventh invention, wherein the transmitting end encodes a predetermined command as information into a multi-level code sequence, and changes the encoding rule based on the command. The receiving end reproduces a predetermined command and changes the decoding rule based on the command.

A nineteenth invention is according to the eleventh invention, and the transmitting end changes the number of amplitude values used for the multi-level code as needed.

A twentieth aspect is according to the eleventh aspect, wherein the transmitting end encodes a predetermined command as information into a multilevel code sequence, and based on the command, an encoding rule, The number of amplitude values used for the multi-level code is changed, and the receiving end reproduces a predetermined command, and changes the decoding rule and the number of amplitude values used for the multi-level code based on the command.

A twenty-first invention is an apparatus for transmitting a multilevel code represented by a plurality of amplitude values from a transmitting end to a receiving end through a transmission path, wherein the transmitting end transmits information to be transmitted to the receiving end. An encoding unit that encodes according to an encoding rule determined based on a relationship between a multi-level code generated in the past and a currently generated multi-level code to generate a multi-level code sequence, A transmitting unit that sends out the generated multi-level code sequence to the transmission path, the receiving end receives the multi-level code sequence through the transmission path, and while following the decoding rule corresponding to the encoding rule,
The decoding unit includes a decoding unit that decodes the multi-level code sequence received by the receiving unit and reproduces information based on a relationship between the multi-level code received by the receiving unit this time and the multi-level code received by the receiving unit before.

A twenty-second invention is according to the twenty-first invention, wherein the decoding unit is configured to perform the decoding based on the relationship between the multi-level code received by the receiving unit this time and the multi-level code received by the receiving unit immediately before. To perform decryption.

A twenty-third invention is according to the twenty-first invention, wherein the information includes a plurality of types of symbols, and the coding unit converts the plurality of types of symbols into a multi-level code of the same pattern in accordance with a coding rule. To generate a multi-level code sequence,
In the generated multi-level code sequence, a change from one symbol to another symbol is expressed by the phase change of the same pattern.

A twenty-fourth invention is according to the twenty-first invention, wherein the encoding unit generates a multi-level code sequence in which the same code is not excessively continuous.

A twenty-fifth invention is according to the twenty-first invention, wherein the transmitting end includes a multiplexing section for multiplexing a plurality of types of symbols as information, and the coding section converts the multiplexed symbol into Encoding is performed according to the encoding rule to generate a multi-level code sequence.

A twenty-sixth invention is according to the twenty-first invention, wherein the encoding unit performs at least once within a predetermined time interval.
Encoding using the maximum and / or minimum amplitude value is performed to generate a multi-level code sequence, and the receiving end further transmits the amplitude value of the multi-level code sequence received by the receiving unit at predetermined time intervals. And a normalizing unit for normalizing based on the maximum and / or minimum amplitude value to be obtained. According to the present invention, the maximum amplitude value and / or the minimum amplitude value of the multi-level code are determined at predetermined time intervals.
The transmitting end notifies the receiving end. The normalization unit normalizes the reception level of the reception unit based on the notified maximum value and minimum value. Thereby, the reception level of the receiving unit is corrected, so that the receiving unit can supply the decoding unit with a multi-level code string indicating an accurate amplitude value.

A twenty-seventh invention is according to the twenty-first invention, wherein the encoding unit and the decoding unit change the encoding rule and the decoding rule as necessary.

A twenty-eighth invention is according to the twenty-first invention, wherein the encoding unit encodes a predetermined command as information into a multilevel code sequence, and changes an encoding rule based on the command. Then, the decoding unit reproduces a predetermined command and changes the decoding rule based on the command.

A twenty-ninth invention is according to the twenty-first invention, wherein the encoding unit and the decoding unit change the number of amplitude values used for the multi-level code as needed.

A thirtieth invention is according to the twenty-first invention, wherein the encoding unit encodes a predetermined command as information into a multi-level code sequence, and, based on the command, an encoding rule, The decoding unit reproduces a predetermined command, and changes the decoding rule and the number of amplitude values used for the multi-level code based on the command.

A thirty-first aspect is an apparatus for optically transmitting a multilevel code represented by a plurality of amplitude values from a transmitting end to a receiving end through an optical transmission line, and the transmitting end should transmit to the receiving end. An encoding unit that encodes information according to an encoding rule determined based on a relationship between a multi-level code generated in the past and a currently generated multi-level code to generate a multi-level code sequence; A light-to-light conversion unit that performs light-to-light conversion on the multi-level code sequence generated by the unit to generate an optical signal, and sends the light signal to an optical transmission line, and the receiving end receives the light signal through the optical transmission line. A photoelectric conversion unit that performs photoelectric conversion to reproduce a multi-level code sequence; a multi-value code that the photoelectric conversion unit has reproduced this time while complying with a decoding rule corresponding to the encoding rule; Multi-level code sequence reproduced by the photoelectric conversion unit based on the relationship with the value code Decoding to include decoder for reproducing information.

A thirty-second invention is according to the thirty-first invention, wherein the decoding unit comprises: a multi-level code reproduced by the photoelectric conversion unit at this time;
Immediately before that, decoding is performed based on the relationship with the multi-level code reproduced by the photoelectric conversion unit.

A thirty-third aspect is according to the thirty-first aspect, wherein the information includes a plurality of types of symbols, and the encoding unit converts the plurality of types of symbols into a multi-level code having the same pattern in accordance with an encoding rule. To generate a multi-level code sequence,
In the generated multi-level code sequence, a change from one symbol to another symbol is expressed by the phase change of the same pattern.

A thirty-fourth invention is according to the thirty-first invention, wherein the encoding unit generates a multi-level code sequence in which the same code is not excessively continuous.

A thirty-fifth invention is according to the thirty-first invention, wherein the transmitting end includes a multiplexing section for multiplexing a plurality of types of symbols as information, and the coding section converts the multiplexed symbol into Encoding is performed according to the encoding rule to generate a multi-level code sequence.

A thirty-sixth invention is according to the thirty-first invention, wherein the encoding unit performs at least once within a predetermined time interval.
Encoding using the maximum and / or minimum amplitude value is performed to generate a multi-level code sequence, and the receiving end transmits the amplitude value of the multi-level code sequence received by the receiving unit at predetermined time intervals. And a normalizing unit for normalizing based on the maximum and / or minimum amplitude values.

A thirty-seventh invention is according to the thirty-first invention, wherein the encoding unit and the decoding unit change the encoding rule and the decoding rule as needed.

A thirty-eighth invention is according to the thirty-first invention, wherein the encoding unit encodes a predetermined command as information into a multi-level code sequence, and changes an encoding rule based on the command. Then, the decoding unit reproduces a predetermined command and changes the decoding rule based on the command.

A thirty-ninth aspect is according to the thirty-first aspect, wherein the encoding unit and the decoding unit change the number of amplitude values used for the multi-level code as needed.

A fortieth invention is according to the thirty-first invention, wherein the encoding unit encodes a predetermined command as information into a multi-level code sequence, and based on the command, an encoding rule, The decoding unit reproduces a predetermined command, and changes the decoding rule and the number of amplitude values used for the multi-level code based on the command.

[0052]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG.
FIG. 10 is a block diagram of a transmission device to which the transmission method according to the embodiment is applied. This transmission device includes a transmitting end 1 and a receiving end 2
Are communicably connected through a wired or wireless transmission path 3. First, the configuration of the transmitting end 1 will be described. Transmitting end 1
Are the first input unit 11, the second input unit 12, the selector 1
3, encoding unit 14, first holding unit 15, and transmitting unit 1
6 inclusive. A data string to be transmitted to the receiving end 2 is sequentially input to the first input unit 11. The first input unit 11
The input data sequence is output to the selector 13. Command symbols are sequentially input to the second input unit 12. The second input unit 12 outputs an input command symbol to the selector 13.

The selector 13 multiplexes the input data sequence and the input command symbol to generate a multiplexed symbol sequence. The generated multiplexed symbol sequence is output to encoding section 14. The data string and command symbol are
At the time of input to the selector 13, the signal formats (amplitude, symbol length, etc.) are not always unified. In this case, the selector 13 unifies the signal formats of the input data string and the command symbol. On the other hand, when both signal formats match, the selector 13 multiplexes the input data sequence and command symbol as they are. The encoding unit 14 is driven by the input multiplexed symbol sequence and performs the following encoding. Therefore, the encoding unit 14 includes a multi-level assignment unit 141 and a multi-level code sequence generation unit 142. The multi-value assignment unit 141
A symbol multiplexed on the input multiplexed symbol sequence is detected.

The multi-value allocating section 141 allocates a predetermined amplitude value to each detected symbol according to a predetermined coding rule. This amplitude value is predetermined according to the multi-level code to be generated. The amplitude value assigned this time (hereinafter, referred to as “current amplitude value”) includes the symbol detected this time and the amplitude value assigned in the past by the multi-value assignment unit 141 (hereinafter, referred to as “past amplitude value”). Is determined based on This past amplitude value is stored in the first holding unit 1
5 is held. Further, the multi-value assignment unit 141
Typically, the current amplitude value is assigned with reference to a table in which coding rules are described. In addition to referring to the table, the current amplitude value is also calculated by a state machine, a logic circuit, or a calculation by a CPU. It can be derived and assigned. The current amplitude value is obtained from the multi-value assignment unit 141.
It is output to the first holding unit 15 and the multi-level code sequence generation unit 142. The multi-level code sequence generator 142 generates a multi-level code sequence according to the input amplitude value, and outputs the generated multi-level code sequence to the transmitter 16.

In the above description, the multi-value assigning section 141 assigns a digitally expressed logical value as an amplitude value.
The multi-level code sequence generation unit 142 can be interpreted as generating a multi-level code sequence having an analog waveform according to the logical value. However, according to the design requirements of the transmission device, the multi-level allocating section 141 may directly generate a multi-level code sequence having an analog waveform from the input multiplexed symbol sequence and past amplitude values. Good.

The first holding unit 15 holds the input current amplitude value. This amplitude value is output to the multi-value assignment unit 141.
Is used as a past amplitude value. The first holding unit 15 holds the past amplitude values in a number determined according to the design requirements of the transmission device. If the current amplitude value is assigned using the previous amplitude value, the first holding unit 15 only needs to hold one amplitude value. In this case, the transmitting end 1 can be made compact, which is more preferable. Hereinafter, a case will be described in which the first holding unit 15 holds only one amplitude value, that is, only the previous amplitude value. The multi-level code sequence output from the encoding unit 14 is input to the transmission unit 16. The transmission unit 16 outputs the input multi-level code sequence to the transmission path 3 as a transmission path code.

Next, the configuration of the receiving end 2 will be described.
The receiving end 2 includes a receiving unit 21, a normalizing unit 22, a second holding unit 23, a decoding unit 24, a first output unit 25, and a second output unit 26. The receiving unit 21 receives the multi-level code sequence transmitted through the transmission path 3 and outputs the multi-valued code sequence to the normalizing unit 22. The normalization unit 22 typically includes an AGC (Automatic G
ain Controller) or ATC (Autom
atic Threshold Control
r), for example, in an AGC, an amplitude value of an output signal of an internal variable gain amplifier (not shown) is detected, and a control signal is generated based on the detected amplitude value.
The generated control signal is fed back to the variable gain amplifier. As a result, the fluctuating received signal level is normalized, and the multi-level code sequence is corrected to a correct amplitude value. The normalized multi-level code sequence is stored in the second holding unit 23 and the decoding unit 2
4 sequentially. The second holding unit 23 includes the receiving unit 21
When the multi-level code sequence output from is input, the amplitude value is held. The second holding unit 23 holds some amplitude values input in the past. The held amplitude value is used at the time of decoding by the decoding unit 24.

The decoding section 24 is driven by the multi-level code string output from the receiving section 21 and performs the following decoding and reproduction processing according to the coding rules used by the coding section 14 and the corresponding decoding rules. The decoding unit 24 operates at a predetermined cycle, and the amplitude value of each multi-level code output from the receiving unit 21, that is, the amplitude value of the multi-level code received this time (hereinafter, referred to as “current amplitude value”). ) Is detected. The decoding unit 24 further includes
The past amplitude value held in the second holding unit 23 is obtained. The decoding rules specify the relationship between the current and past amplitude values and the symbols to be decoded (hereinafter, referred to as decoded symbols). The decoding unit 24 decodes and reproduces a data string or a command symbol from the detected current amplitude value and the past amplitude value obtained from the second holding unit 23 according to the decoding rule. For decoding and reproduction, the decoding unit 24 refers to a table in which decoding rules are described, or performs an operation using a state machine, a logic circuit, or a CPU. The decoding unit 24 further separates the reproduced data string and the command symbol, and
5 and the second output unit 26.

If the symbol to be reproduced is derived from the current and previous amplitude values, the second holding unit 23 only needs to hold one amplitude value. in this case,
It is more preferable because the receiving end 2 can be made compact. First
The output unit 25 and the second output unit 26 output the data sequence and the command symbol output from the decoding unit 24 to the outside of the receiving end 2.

Next, first and second specific examples of the transmission method in the transmission apparatus of FIG. 1 will be described. In the first specific example, encoding and decoding in the case of quaternary transmission will be described. FIG. 2 is a diagram for explaining the encoding rule of the transmitting end 1 in FIG. In particular, FIG. 2A shows a symbol sequence 4 generated by multiplexing information input by the selector 13. In the symbol sequence 4 of FIG. 2A, COM41 and COM42, which are different command symbols, and DATA43 as a data sequence are multiplexed. COM4
1 is time t _{0 to} t ₁ , time t _{2 to} t ₃ , and time t
_{After 5,} it is included in the symbol sequence 4. COM42 is included in t ₄ ~t ₅ time t ₁ ~t _2, and time. DA
TA43 is included in the time t ₃ ~t _4.

FIG. 2 (b) shows the symbol of FIG. 2 (a).
Multiplexed signal sequence 5 (see solid line in the figure)
3) shows an example. As shown in FIG. 2B, the multiplexed signal sequence
At 5, COM41 and COM42 are multiplexed
Time interval, ie time t₀~ T₁, Time t₁~ T_Two,
Time t_Two~ T_Three, Time t_FiveAfter, and at time t_Four~ T _Five
, The same sign continuation occurs. Therefore, the encoding unit 14
By performing the encoding described above, COM41, COM42 and
The same code is not excessively continuous while expressing DATA43
A multi-level code sequence 6 is generated. FIG. 2 (c) is the same as FIG.
When the multiplexed signal sequence 5 is input to the encoding unit 14,
The time waveform of the multi-level code sequence 6 output from the encoding unit 14 (see FIG.
(See solid line). In this specific example, quaternary transmission is used.
The multi-level code sequence 6 is represented by four amplitude values. In this specific example
Are four amplitude values, "W", "X", "Y" and
And “Z” (W> X> Y> Z).

As shown in FIG. 2C, COMs 41 and 4
2 is represented by an alternation of “X” and “Y”. This
As a result, the multi-level code sequence 6 in which the same code is not excessively
Can be generated. The important thing here is that CO
How to express the change from M41 to COM42
It is. In this specific example, both change points are the same level.
It is represented by a value code being repeated twice. For example,
Time t₁Before and after "Y", "Y" continues twice. Also when
Interval t_TwoBefore and after "Y" are repeated twice, and the time t _FiveBefore and after
In this case, "X" is repeated twice. Thus, this coding rule
Then, the same sign sequence, that is, the transition from "X" to "X"
The transition or transition from “Y” to “Y” is COM41
Change from COM42 to COM42, or from COM42 to COM4
It is defined as a change to 1. It is important to note that
Interval t₁And time t_TwoThen, "Y" must be repeated twice
Changes from COM41 to COM42 and COM4
The change from 2 to COM 41 is to be expressed. What
In this coding rule, the way of changing the amplitude value is the same.
Express different command symbols
it can. The receiving end 2 performs decoding and reproduction processing described later.
Even if the relationship between the past and current amplitude values is the same,
Can decode and play back different command symbols.
You.

In the case where COM 41 and COM 42 have the same pattern, changing from the viewpoint of FIG.
Is expressed by the phase of the same pattern. For example, the phase does not change in the time waveform until time t _1. However, in the time waveform immediately after time t ₁ ,
The period and amplitude are the same, but out of phase. That is, a phase change occurs in the multi-level code sequence 6 at the time t ₁ . This phase change, at time t _1, COM4
A change from 1 to COM 42 is represented. The same applies to other times t ₂ and t ₅ .

It is to be noted that COM 41 and COM 42 may be represented by other patterns as long as the condition that the same code sequence does not continue excessively is satisfied. Other patterns are determined according to the characteristics of the transmission path 3. That is, the alternation pattern is a preferable example. The DATA 43 is represented by “W” and “Z”. Note that the encoding unit 14 includes
Data 43 represented by “0” and “1” is input. Therefore, the DATA 43 may be input to the encoding unit 14 without the continuation of the same code. In this case, the encoding unit 14 does not need to assign a multi-level code to the DATA 43. That is, “W” = “1” and “Z”
= “0”. Thereby, the encoding unit 14
Can perform encoding without unnecessary load. Next, an encoding rule when changing from a data string to each command symbol will be described. The transition from “W” or “Z” to “X” is D
The transition from the ATA 43 to the COM 41 is determined. Also, the transition from “W” or “Z” to “Y” is DAT
The transition from A43 to COM42 is defined. In the present embodiment, the multiplexed signal sequence 5 has a signal form represented by a plurality of levels. However, the multiplexed signal sequence 5 can be transmitted by, for example, activating a corresponding signal line as each symbol is selected. That is, in the present invention, it is completely irrelevant to what kind of signal form is adopted as long as it can be transmitted immediately and independently which symbol is selected.

Next, the detailed operation of the transmitting end 1 will be described with reference to FIG. As described above, the selector 13 multiplexes the data sequence and the command symbol input through the first input unit 11 and the second input unit 12, and
The symbol sequence 4 of (a) is generated. The generated symbol sequence 4 is a multiplexed signal sequence 5 having a time waveform shown in FIG.
Is output to the multi-value assignment section 141.

In the period from time t _{0 to} t ₁ , the multi-value assignment unit 14
1 detects the symbol COM41. Further, the multi-value assigning unit 141 extracts the previous amplitude value held in the first holding unit 15. When the extracted one is “X”, the multi-value assignment unit 141 assigns “Y” to the detected COM 41. This “Y” is output to the first holding unit 15 and to the multi-level code sequence generation unit 142. Further, when the extracted previous amplitude value is “Y”, the multi-value allocating unit 141 allocates “X” to the detected COM 41. This “X” indicates that the first holding unit 15 and the multi-level code sequence generation unit 1
42. As a result, from time t _{0 to} t ₁ , the multi-level code sequence generation unit 142 generates a multi-level code sequence 6 consisting of alternating amplitude values “X” and “Y”.

Immediately after time t ₁ , multi-level allocating section 141 converts symbol COM 42 from input multiplexed signal sequence 5.
Is detected. At this time, the first holding unit 15 holds either “X” or “Y” as the previous amplitude value. In this case, the multi-value allocating unit 141 detects the detected CO
The previous amplitude value “X” or “Y” is directly assigned to M42. FIG. 2C shows a case where the previous amplitude value is “Y”. As a result, before and after time t ₁ , multi-level code sequence generation section 142 generates multi-level code sequence 6 having a pattern in which “Y” is repeated twice.

The multi-value assignment section 141 detects the COM 42 from the time t ₁ to the time t ₂ . Therefore,
The multi-level allocating section 141 alternately allocates “Y” and “X” in this time interval and outputs the result to the first holding section 15 and the multi-level code sequence generating section 142. As a result, a multi-level code sequence 6 including alternations of “Y” and “X” is generated between times t ₁ and t ₂ .

The multi-value allocating section 141 calculates the time t _{2 to} t ₃
, The symbol COM41 is detected. In this time section, an amplitude value is assigned in the same manner as described above, and the multi-level code sequence 6 is generated. The As a result, the time t ₂ ~t _3,
A multi-level code string 6 including alternations of “Y” and “X” is generated. However, in the same manner as described above, to represent a change to COM41, time t ₂ before and after, the same reference numerals level "Y" is 2
Repeated times. By this repetition, time t _{1 to} t ₂
And alternating pattern, the phase changes of the alternating pattern of the time t ₂ ~t _3, changes from COM42 to COM41 is expressed. Immediately after time t ₃ , multi-value assignment section 141 detects DATA 43 (“1” or “0”).
At this time, the first holding unit 15 holds either “X” or “Y” as the previous amplitude value. In this case, the multi-value allocating unit 141 detects the detected DATA 42
Is assigned an amplitude value “W” or “Z”. Hereafter, D
ATA43 time t ₃ ~t ₄ to be inputted, the multi-level code sequence 6 represented by enumeration of "W" and "Z" is generated.

The multi-value assignment unit 141 detects the COM 42 immediately after the time t ₄ . At this time, the first holding unit 1
5 holds either “W” or “Z” as the previous amplitude value. Thereby, the multi-value assignment unit 14
It can be seen that 1 has changed from DATA43 to COM42. In this case, the multi-value allocating unit 141 initially allocates the amplitude value “Y”. As a result, before and after time t ₄ , the amplitude value changes from “W” or “Z” to “Y”, whereby a change from DATA 43 to COM 42 is expressed. Until time t ₅ after the initial amplitude value “Y” is assigned, “X” is used in accordance with the above-described encoding rule.
And "Y" are assigned alternately.

Note that although not shown in FIG.
When the ATA 43 changes to the COM 41, the multi-value allocating unit 141 initially allocates “X” as described above. Further, the COM 41 is detected after the time t ₅ , but since the assignment of the amplitude value at this time is as described above, the description is omitted. As a result, after time t ₀ , the multi-level code sequence 6 in FIG.
42 and output to the transmission unit 16. The transmission unit 16 outputs the input multi-level code sequence 6 to the transmission path 3.

FIG. 3 shows a decoding rule preset in the decoding unit 24 of FIG. The decoding rule in FIG. 3 shows the previous and current amplitude values and decoded symbols. The decoding rules will be specifically described in order from the top in FIG. 1. If the previous amplitude value is “W” or “Z” and the current amplitude value is “X”, the decoded symbol is the reception of COM41. 2. If the previous amplitude value is “W” or “Z” and the current amplitude value is “Y”, the decoded symbol is the COM42 reception. 3. When the current amplitude value is “W”, the decoded symbol is DA
This is the reception of “1” of TA43. 4. If the current amplitude value is “Z”, the decoded symbol is DA
This is the reception of “0” of TA43. 5. If the previous amplitude value is “X” and the current amplitude value is “Y”, the decoded symbol is the same as the previous decoded symbol. 6. If the previous amplitude value is “Y” and the current amplitude value is “X”, the decoded symbol is the same as the previous one. 7. If the previous and current amplitude values are both "X", the decoded symbol is a change in the command symbol, that is, a change from COM41 to COM42 or a change from COM42 to COM41. 8. Even when the previous and current amplitude values are both “Y”, the decoded symbol is a change in the command symbol as described above.

Next, the detailed operation of the decoding unit 24 in FIG.
This will be described with reference to FIGS. The decoding unit 24
Operations other than those described above are not important points of the present embodiment and are apparent from the above description, and thus will be briefly described. The multi-level code sequence 6 received by the receiving unit 21 is input to the decoding unit 24 and the second holding unit 23 after being normalized by the normalizing unit 22.

[0074] multi-level code sequence 6, since it is transmitted through the transmission line 3, as shown in FIG. 2 (d), delta based on the time t ₀
The signals are sequentially input to the decoding unit 24 with a delay of t. The decoding unit 24 detects the amplitude value of the input multi-level code sequence 6.
Since the multi-level code sequence 6 output from the receiving unit 21 is input to the second holding unit 23, the same amplitude value as that detected by the decoding unit 24 last time is held. The decoding unit 24 extracts the previous amplitude value from the second holding unit 23 every time the amplitude value is detected.

The decoding section 24 alternately detects “X” and “Y” as the current amplitude value during the time t _{6 to} t ₇ (FIG. 2).
(See (d)), "Y" and "X" are obtained alternately as the previous amplitude value. That is, if the previous amplitude value is “Y”,
This time is “X”, and if the previous amplitude value is “X”, this time is “Y”. Such a relationship between the previous and current amplitude values is described in Section 5. Or 6.
(See FIG. 3). Therefore, the decoding unit 24
At time t ₆ ~t _7, decodes the multi-level code sequence 6 according to the above decoding rules and continues to reproduce the COM41 as a decoded symbol. The decoding unit 24 outputs the reproduced COM 41 to the second output unit 26.

The decoding unit 24 calculates the time t₇Immediately after this
“Y” is detected as the width value (see FIG. 2D). Ma
In addition, the second holding unit 23 operates at time t₇Immediately before the receiving unit 2
1 holds the amplitude value “Y” output from
24 is the time t₇Immediately after the second holding unit 23
The amplitude value “Y” is obtained. The previous amplitude value was “Y” and now
The relation of “Y” for the times is based on “8. Corresponds to
I do. Therefore, the decoding unit 24 calculates the time t₇Before and after
It detects that the command symbol has changed. In this specific example
Is the command symbol of COM41 and COM42
Is assumed. Therefore, the decoding unit 24 calculates the time t₇
Before receiving COM41, the time t₇Directly
Later, the change from COM41 to COM42 is detected
Then, the reproduction of the COM 42 is started as a decoded symbol.
Time t₇~ T₈Then, time t₆~ T ₇As in
If the previous amplitude value is "Y", this time is "X"
Yes, if the previous amplitude value is "X",
"Y". Therefore, the decoding unit 24 calculates the time t₇~
t₈In the example, COM42 is reproduced as a decoded symbol.
to continue. The decoding unit 24 converts the reproduced COM 42 into a second
Output to the output unit 26. The second holding unit 23 operates at time t₈
Immediately after, the previous amplitude value “Y” is held. At the same time,
The signal unit 24 detects the current amplitude value “Y” (see FIG. 2).
(D)). In this case, the time t₇The same procedure as in
And decryption rule 8. According to the time t₈Before and after
It is detected that the symbol has changed. by this,
Reproduction of the COM 41 as a decoded symbol is started. Time
Interval t₈~ T₉Then, the relationship between the previous and current amplitude values is
4. Decoding rules And 6. Alternately follows, so that the time t₈~
t₉Now, COM41 is played back as a decoded symbol
I can. This COM 41 is output to the second output unit 26
You.

The decoding section 24 continues to detect either “W” or “Z” as the current amplitude value during the time t _{9 to} t ₁₀ (see FIG. 2D). During this time, the decoding unit 24 does not obtain the previous amplitude value from the second holding unit 23, Or 4. , "0" or "1" is continuously reproduced as a decoded symbol. That is, DATA
43 is reproduced. The decoding unit 24 outputs the reproduced DATA
43 is output to the first output unit 25. As described above, since the decoding unit 24 does not retrieve the past amplitude value from the second holding unit 23 in the case of the DATA 43, the decoding and the reproduction can be performed with a lighter load as compared with the case of the COM 41 and the like. However, even during the time t _{9 to} t ₁₀ , the second holding unit 23
The amplitude value “W” or “Z” output from the receiving unit 21 is input. Therefore, the second holding unit 23 sets the time t ₁₀
Immediately after, “W” or “Z” is held as the previous amplitude value. At the same time, the decoding unit 24 detects “Y” as the current amplitude value (see FIG. 2D). The relationship between the two amplitude values is described in 2. Corresponds to. Therefore, the decoding unit 2
4, immediately after the time t _10, COM as decoded symbol
42 is started.

FIG. 2D does not show a case where the previous amplitude value is “W” or “Z” and the current amplitude value is “X”. The relationship between the two amplitude values is determined according to 1. Corresponds to. As described above, when the multivalue assignment section 141 changes from DATA43 to COM41, the amplitude value “X” is initially assigned, so that the encoding rule and the decoding rule uniquely correspond. Although COM41 the time t ₁₁ and subsequent steps are detected, decoded and reproduced at this time, since carried out in the manner described above, and a description thereof will be omitted.

As described above, in this transmission method, the transmitting end 1
Represents transmission information to the receiving end 2 by the relationship between the amplitude value of the transmitted multi-level code and the amplitude value of the current transmission. That is, the transmitting end 1 can perform encoding if the relationship between the past and present amplitude values is known. On the other hand, in 4B5B encoding, a 5-bit transmission line code is generated after waiting for 4-bit transmission information to be completed. In other words, 4B5B
In encoding, it is necessary to wait for transmission information to be input in the future. However, the transmitting end 1 of the present transmission method refers to past amplitude values and assigns current amplitude values to perform encoding without waiting for future transmission information. Therefore, the transmitting end 1
Can perform higher-speed encoding than 4B5B encoding or the like.
Further, the decoding unit 24 of the receiving end 2 performs decoding according to the relationship between the amplitude value of the received multi-level code and the one received this time. The receiving end 2 can also decode and reproduce the transmitted information only by knowing the relationship between the past and present information. On the other hand, in 4B5B decoding, 4-bit information is not reproduced unless 5-bit information is prepared. In other words, 4
In B5B decoding, it is necessary to wait for transmission information to be input in the future. However, since the receiving end 2 does not need to wait for future transmission information, it can perform faster decoding than 4B5B decoding or the like. Accordingly, it is possible to provide a transmission method and a transmission apparatus capable of transmitting information from the transmitting end 1 to the receiving end 2 with a smaller transmission delay. Furthermore, in the present transmission device, the encoding unit 14 generates the multi-level code sequence 6 in which the same code is not excessively continuous. With this multi-level code sequence, DC balance can be achieved in the transmission path 3, so that the transmitting end 1 and the receiving end 2
The drift of the average value of the signal can be suppressed.

In the transmission method and the transmission apparatus, information to be transmitted is represented by a relationship between two amplitude values selected from multiple values (that is, past and present amplitude values). There are a considerable number of ways to select these two amplitude values because they are multi-level codes. That is, a relationship between two amplitude values (that is, a combination of two values) can be created by the number corresponding to the multi-value without generating the same sign continuation. This combination can be assigned to commands and / or data. Therefore, the encoding unit 14 can easily convert the multiplexed signal sequence 5 in which commands and data are multiplexed into the multi-level code sequence 6.

As a method of encoding based on past and present amplitude values, NRZ-I (Non Ret)
(urn to Zero-Inverse) coding. This NRZ-I encoding detects a change point between "0" and "1" in an input binary data string, assigns "1" if a change point is detected, and detects a change point. If not, "0" is assigned. However, in the NRZ-I coding, if there is no change from “0” to “1” or “1” to “0”, “0” is continuously assigned for a long time. As a result, the NRZ-I encoding generates a code sequence having the same code continuation depending on the input binary data sequence. As a result, the DC balance in the transmission path deteriorates, and it becomes impossible to transmit correct information. As described above, in the transmission method and the transmission device according to the present embodiment, the above-described specific effects are produced by combining information with past and current amplitude values and multi-level transmission.

By the way, the transmission method and the transmission apparatus are as follows.
The above-described effects can be obtained as long as multi-level codes of three or more levels are transmitted, without being limited to four-level transmission. Next, as a second specific example, a case where the present transmission method and the transmission apparatus perform ternary transmission will be described. Note that the configuration of the transmission device of the second specific example is the same as that of the first specific example, so that its illustration is omitted. That is, FIG. 1 is referred to in the following description. The difference between the two specific examples is the encoding rule and the decoding rule of the encoding unit 14 and the decoding unit 24. Hereinafter, this difference will be described.

FIG. 4 is a diagram for explaining the coding rules of this specific example. FIG. 4A shows a symbol sequence 7 output from the selector 13. In the symbol column 7,
COM 71 as a command symbol and DATA 72 as a data string are multiplexed. In this symbol sequence 7, the COM 71 determines the time t _{0 to} t ₁ and the time t ₂ to t ₂ .
included in t _3, DATA72 is included in the time t ₁ ~t _2. The selector 13 outputs a multiplexed signal sequence as an example of the symbol sequence 7 in FIG. However, from the viewpoint of simplification of description, this multiplexed signal sequence is assumed to be the same as that of the first specific example (see FIG. 2B), and is not illustrated or described in detail.

FIG. 4B shows a time waveform (see the solid line in the figure) of the multi-level code sequence 8 output by the coding unit 14 in response to the multiplexed signal sequence. In the multi-level code sequence 8, COM 71 and DATA 72 are represented by three amplitude values. In this specific example, “X”, “Y”, and “Z” (where X>Y> Z) are used as the three amplitude values. If the multiplexed signal sequence is generated in the same manner as in the first example, CO
M71 has the same code continuation when input to the encoding unit 14. COM71 indicates the amplitude value “Y” or “Z”
Is represented by a change from “X” to “X”. Furthermore, COM
71 is also represented by a change from the amplitude value “X” to “Z”. Thereby, in the multi-level code sequence 8, C
The OM 71 is basically expressed by an alternation of “X” and “Z”. This makes it possible to generate a multi-level code sequence 8 in which the same code is not excessively continuous.

The symbol of DATA 72 is either "0" or "1". In this specific example, “1” indicates a change in amplitude value from “X” to “Y” and “Y” to “Z”.
, And a change from “Z” to “Y”. That is, mutually different amplitude values are assigned to “1” this time according to the previously assigned amplitude value. In addition, “0” indicates a change from “X” to “X”, a change from “Y” to “Y”, and a change from “Z” to “Z”.
Assigned to any of the changes to. That is, "0"
, The same value as the previous amplitude value is assigned this time.

Next, the detailed operation of the encoding unit 14 of this example will be described with reference to FIGS. Selector 1
The symbol sequence 7 in FIG. 4A output from 3 is input to the multi-value assignment unit 141. From time t _{0 to} t ₁ , the COM 71 is input to the multi-value assignment unit 141. The multi-value assignment unit 141 detects the COM 71 and
When the holding unit 15 holds “Z” as the previous amplitude value, “X” is assigned as the current amplitude value. This “X” indicates that the first holding unit 15 and the multi-level code sequence generation unit 1
42. When the previous amplitude value is “X”, the multi-value assigning unit 141 determines that the current amplitude value is “Z”.
Assign. “Z” is output to the first holding unit 15 and the multi-level code sequence generation unit 142. As a result, time t ₀
From to t ₁ , the multi-level code sequence generation unit 142 generates, as the COM 71, the multi-level code sequence 8 composed of alternating “X” and “Z”.

Immediately after time t ₁ , multi-value allocating section 141 determines whether “0” or “1”
(DATA72) is detected. At this time, either “X” or “Z” is set as the previous amplitude value in the first holding unit 1.
5 is held. Assume that “X” is assigned immediately before time t ₁ as shown in FIG. In this case, when detecting “0” immediately after the time t ₁ , the multi-value assignment unit 141 assigns the previous amplitude value “X” as the current amplitude value as it is. On the other hand, the multi-value allocating unit 141 determines that “X” is allocated immediately before time t ₁ ,
If detected immediately after the "1" in the time t _1, assigns "Y" as the current amplitude value. As a result, “1” is expressed as a change from the amplitude value “X” to “Y” as described above. The multi-value assigning unit 141 immediately after the time t ₁ ,
Either “X” or “Y” is assigned as the current amplitude value, and the amplitude value is output to the multi-level code sequence generation unit 142 and the first holding unit 15.

The multi-value allocating section 141 calculates the time t _{1 to} t ₂
Up to the input DA according to the above-described encoding rule.
An amplitude value is assigned to TA72. Now, assuming that “0” is continuously detected from time t ₁ , multi-value assigning section 141 continues to assign “X” held in first holding section 15 immediately before time t ₁ . Multi-value assignment section 141
Is the amplitude value “Y” at the time when it changes from “0” to “1”.
Assign. According to the above encoding rule, the multi-value allocating unit 141 responds to “0” or “1” detected after allocating “Y” for the first time from time t _{1 to} t ₂ ,
Assign "Y" or "Z". As a result, time t ₁
From t _{2 to} t ₂ , the multi-level code sequence generation unit 142 generates the multi-level code sequence 8 including the amplitude value “X” until “1” is detected, as shown in FIG. Also, a multi-level code sequence generation unit 1
42, after detecting "1" (see time point of arrow A)
Until time t ₂ , a multi-level code sequence 8 represented by a series of amplitude values “Y” or “Z” is generated.

The multi-value allocating unit 141 calculates the time t_TwoOr later,
COM71 is detected. In addition, the first holding unit 15
Interval t_TwoImmediately before the “Y” or
One of “Z” is held. Multi-value assignment section 141
Is detected regardless of which amplitude value is held.
"X" is assigned as the current amplitude value to COM71
Te As a result, the data from DATA 72 to COM 71
Changes are represented by a transition from “Y” or “Z” to “X”.
Will be revealed. Thereafter, the multi-value assignment unit 141
Assign "Z" or "X" alternately while detecting
You. As a result, time t _TwoHereinafter, the multi-level code sequence generation unit 1
42 is a multi-value consisting of alternating values of the amplitude values "X" and "Z"
A code string 8 is generated.

In the example of FIG. 4B, immediately before t ₂ , the first holding unit 15 stores “Y” as the previous amplitude value.
Alternatively, “Z” is held. However, DATA72
A case where only “0” is formed from time t _{1 to} t ₂ can be assumed. Therefore, the first holding unit 15 may hold “X” as the previous amplitude value immediately before the time t ₂ . In this case, the COM 71 detected immediately after the time t ₂
Is assigned “Z”. Thereafter, “X” or “Z” is alternately assigned to the detected COM 71 as described above. Therefore, just prior to time t _2, even when holding a "X" as the preceding amplitude value, the multilevel code string 8 composed of alternation of the amplitude values "X" and "Z" is generated.

FIG. 5 shows an example of the decoding rule of this example. The decoding rule in FIG. 5 shows the previous and current amplitude values and the decoded symbols. The decoding rules will be specifically described in order from the top in FIG. FIG. 5 shows an example of a decoding rule preset in the decoding unit 24 in the case of ternary transmission. The decoding rule in FIG. 5 shows the relationship between the previous and current amplitude values and the decoded symbols. Hereinafter, decoding rules 1. ~
5. Is specifically described.

1. If the previous amplitude value is “X” and the current amplitude value is “Z”, the decoded symbol is the reception of the COM 71. 2. If the previous amplitude value is “Y” or “Z” and the current amplitude value is “X”, the decoded symbol is COM71 reception. 3. If the previous amplitude value is “X” or “Z” and the current amplitude value is “Y”, the decoded symbol is DATA7
This is the reception of "1" of 2. 4. When the previous amplitude value is “Y” and the current amplitude value is “Z”, the decoded symbol is “1” of DATA 72.
Is received. 5. When the previous and current amplitude values are “X”, “Y”, or “Z”, respectively, the decoded symbol is the reception of “0” of DATA 72.

Next, the detailed operation of the decoding section 24 in this specific example will be described with reference to FIGS. 1, 4 and 5.
Note that the operation of the configuration other than the decoding unit 24 at the receiving end 2 has been described above, and will not be described here. Here, FIG. 4C shows a time waveform of the multi-level code sequence 8 input to the decoding unit 24. The multi-level code sequence 8 in FIG. 4C is different from that in FIG. 4B only in that it involves a transmission delay Δt due to the transmission path 3.

When the multi-level code sequence 8 is input, the decoding unit 24 periodically detects the amplitude value. Second holding unit 23
Holds the amplitude value of each multi-level code constituting the multi-level code sequence 8 output from the receiving unit 21. The decoding unit 24 obtains the previous amplitude value from the second holding unit 23 every time the amplitude value is detected. The decoding unit 24 alternately detects “X” and “Z” as the current amplitude value from time t _{3 to} t ₄ (see FIG. 4).
(See (c)), "Z" and "X" are obtained alternately as the previous one. That is, if the previous amplitude value is “Z”, the current value is “X”, and if the previous amplitude value is “X”, the current value is “Z”. The relationship between the previous and current amplitude values is determined according to 1. Or 2. Corresponds to.
Accordingly, the decoding unit 24, the time t ₃ ~t _4, when decoding the multilevel code string 8, continue to play a COM71 as a decoded symbol.

At time t ₄ , the amplitude value “X” is held by the second holding unit 23. Further, the decoding unit 24 calculates the time t
Immediately after step ₄ , "X" or "Y" is detected as the current amplitude value (see FIG. 4C). The decoding unit 24 obtains “X” as the previous amplitude value. The relationship that the previous and current amplitude values are “X” corresponds to “5. Corresponds to. In this case, the decoding unit 24 sets DATA7 at time t ₄ .
2 is detected, and "0" is reproduced as a decoded symbol. The relationship that the previous amplitude value is “X” and the current amplitude value is “Y” is determined by the decoding rule 3. Corresponds to. In this case, the decoding unit 24
The start of reception of the ATA 72 is detected, and “1” is reproduced as a decoded symbol. At times t _{4 to} t ₅ , the relationship between the previous and current amplitude values is 3. ~ 5. Therefore, the decoding unit 24 reproduces either “0” or “1” as a decoded symbol.

At time t ₅ , the amplitude value “Y” or “Z”
Is held by the second holding unit 23. Also, the decoding unit 2
4 detects the "X" as the current amplitude value immediately after time t ₄ (see FIG. 4 (c)). The decoding unit 24 obtains either “Y” or “Z” as the previous amplitude value. The relationship between the previous amplitude value of “Y” or “Z” and the current amplitude value of “X” corresponds to 2. Corresponds to. In this case, decoding unit 24, the time t _5, C as decoded symbol
Start playing OM71. The time t ₅ since, as described above, the relationship between the previous and current amplitude values, 1 in FIG. Or 2. Therefore, the decoding unit 24
The COM 71 is reproduced as a decoded symbol.

In the example of FIG. 4C, immediately before t ₅ , the second holding unit 15 stores “Y” as the previous amplitude value.
Alternatively, “Z” is held. However, DATA72
A case where only “0” is assumed from time t _{4 to} t ₅ can be assumed. In this case, the time t _2, there is a case where "X" is held as the preceding amplitude value. In this case, the decryption unit 24
The amplitude value “Z” is detected immediately after time t ₂ . The relationship that the previous amplitude value is “X” and the current amplitude value is “Z” corresponds to the decoding rule of FIG. Corresponds to. Therefore, the decoding unit 2
4 reproduces the COM 71 as a decoded symbol.

As described above, even in the case of ternary transmission, the transmitting end 1 determines the amplitude value of the transmitted multi-level code and
Information to be transmitted to the receiving end 2 is represented by the relationship with the amplitude value of the current transmission. Therefore, as mentioned above,
The transmitting end 1 can perform high-speed encoding. Further, the decoding unit 24 of the receiving end 2 performs decoding according to the relationship between the amplitude value of the received multi-level code and the one received this time. Therefore, the receiving end 2 can perform high-speed decoding. Accordingly, it is possible to provide a transmission method and a transmission apparatus capable of transmitting information from the transmitting end 1 to the receiving end 2 with a smaller transmission delay. Encoding unit 1
4 generates a multi-level code sequence 8 in which the same code is not excessively continuous. This multi-level code sequence allows DC balance in the transmission path 3, so that it is possible to prevent the average value of the signal from drifting at the transmitting end 1 and the receiving end 2. Further, even in the case of ternary transmission, the transmitting end 1 can send out a multi-level code string 8 in which commands and data are multiplexed. As described above, in the transmission method and the transmission apparatus according to the present embodiment, a special effect is produced by combining information with past and present amplitude values and multi-level transmission.

The concept of the present embodiment is not limited to ternary transmission and quaternary transmission, but can be applied to a method and an apparatus for transmitting a multi-level code of three or more values. The value of the multi-level code is set to an appropriate value depending on the number of commands to be transmitted and the like. Further, in the present embodiment, since the data string is originally represented by “0” and “1”, “Z” is simply assigned to “0” assuming that the same code does not exist in advance,
“1” was assigned to “W”. However, this assignment is a preferred embodiment, and two different amplitude value changes may be assigned to “0” and “1”.

(Second Embodiment) In the first embodiment, the receiving end 2 shown in FIG. 1 is provided with a normalizing section 22 for normalizing the received signal level of the receiving section 21. However, when the receiving unit 21 continuously receives the intermediate amplitude value for a long time (in the example of FIG. 2, “X” and “Y” correspond to the intermediate amplitude values), the normalizing unit 22 performs Cannot be normalized. This is because the normalizing unit 22 defines an intermediate amplitude value based on the maximum amplitude value and the minimum amplitude value of the multi-level code input from the receiving unit 21. That is, if the intermediate amplitude value continues for a long time, the receiving unit 21 cannot know the maximum or minimum amplitude value, and cannot amplify the received multi-level code sequence 6 or 8 to a correct amplitude value. Thus, the transmission method according to the second embodiment is effective. The configuration of the transmission apparatus according to the second embodiment is the same as that of FIG. That is, FIG. 1 is referred to in the following description. The difference between the two specific examples is the encoding rule and the decoding rule of the encoding unit 14 and the decoding unit 24. Hereinafter, this difference will be described.

Next, in the second embodiment, four-level transmission
The following is an example of this case. FIG. 6 shows the transmission of FIG.
FIG. 9 is a diagram for describing an encoding rule of end 1; In particular, the figure
6 (a) and 6 (b) are the same as FIGS. 2 (a) and 2 (b).
Therefore, their description is omitted. FIG. 6 (c)
Is obtained by inputting the multiplexed signal sequence 5 of FIG.
Of the multi-level code sequence 9 output by the encoding unit 14
The time waveform (see the solid line in the figure) is shown. In FIG. 6 (c),
As four amplitude values, “W”, “X”, “Y” and
“Z” (W> X> Y> Z) is used. FIG.
As shown in (c), in the multi-level code sequence 9, COM41 and COM41 are used.
And 42 are the maximum amplitude value “W” and the minimum amplitude value
Represented by "Z", DATA43 is a medium amplitude value
Expressed by "X" and "Y". 2 (c)
The value code string 6 has the opposite relationship to the multi-value code string 9. This
The multi-level code sequence 9 differs from the multi-level code sequence 6 in the following point. It
In other respects, the multi-level code sequence 9 is different from the multi-level code sequence 6
The same is true. In addition, from "X" or "Y" to "W"
A transition is defined as a transition from DATA43 to COM41.
It is. Also, transition from “X” or “Y” to “Z”
Is defined as a transition from DATA43 to COM42.
You. Such a COM41 or COM42 has a predetermined
It is generated at least once in the period T. This predetermined period
Is based on the time constant of AGC or ATC (normalization unit 22).
Is determined. Next, the detailed operation of the transmitting end 1 will be described with reference to FIG.
It will be described with reference to FIG. The multiplexed signal sequence 5 shown in FIG.
From the selector 13 to the multi-value assignment unit 141 of the encoding unit 14
Sent to. The multi-value assigning unit 141 uses the encoding rule
Therefore, the previous amplitude value held in the first holding unit 15 is
While referring to the time t₀~ T₁COM detected in
“W” and “Z” are alternately assigned to 41. The result
Result, time t₀~ T₁Then, the multi-level code sequence generation unit 142
Multi-level code sequence 9 composed of alternating values of amplitude values “W” and “Z”
Generate The multi-value allocating unit 141 calculates the time t₁Immediately after
Next, COM42 is detected. At this time, the first holding unit 1
When “Z” is held as the previous amplitude value in 5
Indicates that the multi-value assigning unit 141 assigns
This “Z” is assigned as it is. As a result, time t₁
Before and after, the multi-level code sequence generation unit 142 repeats “Z” twice.
A multi-level code string 9 to be returned is generated. Multi-value assignment unit 14
1 is the time t₁~ Time t_TwoCOM42 is detected during
Therefore, referring to the previous amplitude value, "Z" and "W"
Are assigned alternately. As a result, time t₁~ T_TwoIn
A multi-level code sequence 9 including alternations of “Z” and “W” is generated.
It is. The multi-value allocating unit 141 calculates the time t_Two~ T_ThreeIn
Since COM41 is detected, the amplitude value is calculated in the same manner as described above.
Are assigned, and a multi-level code sequence 9 is generated. The result
Result, time t_Two~ T_ThreeHave the alternation of "Z" and "W"
A multi-level code sequence 9 including the data is generated. Multi-value assignment section 141
Is the time t_ThreeTo "1" or "0" detected immediately after
On the other hand, while referring to the previous amplitude value, the amplitude value “X” or
Assigns "Y". After that, DATA43 is input
Time t_Three~ T_FourAre represented by a series of "X" and "Y"
A multi-level code sequence 9 to be represented is generated. Multi-value assignment unit 1
41 is the time t_FourImmediately after, COM42 is detected. This
, The first holding unit 15 stores the previous amplitude value
Either “X” or “Y” is held. Multi-value division
The abutment unit 141 determines whether the previous amplitude value is “X” or “Y”.
Presence and detection of COM42, DATA4
It turns out that it changed from 3 to COM42. in this case
, The multi-value allocating unit 141 assigns
An amplitude value “Z” is initially assigned. As a result, time t
_FourBefore and after, the amplitude value changes from “W” or “Z”
The state transitions to “Y”, which causes DATA 43 to output CO
The change of M42 is expressed. Divide the initial amplitude value "Z"
Time t after hit _FiveUp to the encoding rules described above.
Thus, “W” and “Z” are alternately assigned. Less than
The encoding unit 14 performs detection according to the encoding rule described above.
Assign an amplitude value to the symbol. As a result, time
t₀Thereafter, the multi-level code sequence 9 in FIG.
Generated by the generation unit 142 and output to the transmission unit 16
You. The transmission unit 16 converts the input multi-level code sequence 9 into the transmission path 3
Output to FIG. 7 shows the configuration of the decoding unit 24 according to the present embodiment in advance.
Indicates the decoding rule to be defined. The decryption rule in FIG.
The current amplitude value and the decoded symbol are shown. Figure
7, the decoding rules will be specifically described in order. 1. The previous amplitude value is "X" or "Y" and now
If the number of times is "W", the decoded symbol is
Receiving. 2. The previous amplitude value is "X" or "Y" and now
If the number of times is “Z”, the decoded symbol is
Receiving. 3. If the current amplitude value is “X”, the decoded symbol is DA
This is the reception of “1” of TA43. 4. If the current amplitude value is “Y”, the decoded symbol is DA
This is the reception of “0” of TA43. 5. The previous amplitude value was “W” and this time
In the case of "Z", the decoded symbol is
Is the same. 6. The previous amplitude value is "Z" and the current one is
In the case of "W", the decoded symbol is the same as the previous symbol.
You. 7. When the previous and current amplitude values are both "W"
The decoded symbol is the change of the command symbol,
Change from COM41 to COM42 or COM42
To COM41. 8. When the previous and current amplitude values are both "Z"
In this case, the decoded symbol is
It is a change. Next, the operation of the decoding unit 24 will be described with reference to FIGS.
explain. The multi-level code sequence 9 is received by the receiver 21.
After being normalized by the normalizing unit 22, the decoding unit 24
And input to the second holding unit 23. Required for transmission in the figure
The delay time is Δt. The second holding unit 23 is a decoding unit
24 holds the same amplitude value as that detected last time. Return
The signal unit 24 detects the amplitude value of the input multi-level code sequence 9.
Each time, the previous amplitude value is obtained from the second holding unit 23,
Decoding and reproduction of the multi-level code sequence 9 in accordance with the decoding rule 7
Do. This decoding and reproduction processing is described in the first embodiment.
Since the configuration is the same as that of the embodiment, the description is omitted. Second fruit
What is important in the embodiment is that the receiving unit 21 has a predetermined period.
Once every T, COM41 or COM42 must arrive
Therefore, the normalization unit 22 determines whether the predetermined period T (that is, its own
Once a time constant), the maximum amplitude value “W” and the minimum
Receiving the width value "Z". Therefore, normalization
The unit 22 includes a maximum amplitude value “W” and a minimum amplitude value
Accurately normalizes multi-level code sequence 9 by "Z" received signal
it can. Therefore, the decoding unit 24 at the subsequent stage and the second holding
The amplitude value assigned at the transmitting end 1 is given to the unit 23.
Multi-level code having "W", "X", "Y" and "Z"
Column 9 is entered.

(Third Embodiment) In the first and second embodiments, fixed encoding rules and decoding rules are set in the transmission device. In addition, it is assumed that this transmission device is installed in various environments. Further, the surrounding environment of the transmission device is not constant but changes with time. In such an environment, it is assumed that the multi-level code sequence 6 or 8 transmitted by the transmission end 1 of the transmission device may maintain DC balance at one time but may not maintain DC balance at another time. it can. Furthermore, it can be assumed that the multi-level code sequence 6 or 8 maintains DC balance at a certain place but does not maintain DC balance at another place. Therefore, the transmission device according to the third embodiment is effective for always maintaining the DC balance of the multi-level code sequence 6 or 8.

The configuration of the transmission apparatus according to the third embodiment is similar to that of FIG.
Since it is the same as that of FIG. That is, FIG. 1 is referred to in the following description. The difference between the two embodiments is that the encoding rules and the decoding rules of the encoding unit 14 and the decoding unit 24 are changed as necessary. Therefore, a plurality of sets of encoding rules and decoding rules need to be set in the transmission device. Below, as a specific example,
The case where the first and second encoding rules are set in the encoding unit 14 and the first and second decoding rules are set in the decoding unit 24 will be described. In the following example, a case of quaternary transmission will be described.

FIG. 8 is a diagram for explaining the first and second coding rules of the transmitting end 1. FIG. 8A shows a symbol sequence 17 output from the selector 13.
The symbol column 17 includes COM as a command symbol.
171 and COM 172, and DAT as a data string
A173 is multiplexed. In this symbol row 17, C
OM171 is included in the time t ₀ ~t _1, time t ₂ ~t _3, the time t ₄ ~t ₅ and time t ₆ ~t _7. COM1
72 is included in the time t ₃ ~t ₄ and time t ₇ ~t _8. DATA173 is, time t ₁ ~t ₂ and time t ₅
It is included in the ~t _6. The selector 13 outputs a multiplexed signal sequence representing the symbol sequence 17 in FIG. However, from the viewpoint of simplification of description, this multiplexed signal sequence is the same as that of the first specific example (see FIG. 2B), and is not shown or described in detail. FIG. 8B shows a case where the symbol sequence 17 of FIG. 8A is input to the encoding unit 14.
5 shows a time waveform (see a solid line in the figure) of the multi-level code sequence 18 output by. Also in the present embodiment, as four amplitude values,
"W", "X", "Y" and "Z" (where W> X
>Y> Z).

As shown in FIG. 8B, in this embodiment, in the time section T ₁ (that is, from time t _{0 to} t ₄ and after time t ₈ ), the number of symbol strings 17 is large according to the first encoding rule. It is encoded into a value code string 18. In the first encoding rule, COM 171 and COM 172 are represented by alternating “W” and “Z”. Also, COM17
The change from 1 to COM 172 is represented by two consecutive multi-level codes of the same amplitude value. These points are the same as those of the first specific example, and thus detailed description is omitted. Further, “1” and “0” of DATA 173 are represented by “X” and “Y”. Also, DATA
The transition from 173 to COM 171 is expressed as a change from “X” or “Y” to “W”. DATA
The transition from 173 to COM 172 is expressed as a change from “X” or “Y” to “Z”.

The time interval T ₂ (that is, time t _{4 to} t _4)
8 ), the symbol sequence 17 is encoded into a multi-level code sequence 18 according to the second encoding rule. In the second coding rule, COMs 171 and 102 are represented by alternating “X” and “Z”. Further, the point that the change from COM 171 to COM 172 is represented by two consecutive multi-valued codes having the same amplitude value is the same as in the first encoding rule. Further, “1” and “0” of DATA 173 are represented by “W” and “Y”. Also,
The transition from DATA 173 to COM 171 is expressed as a change from “W” or “Y” to “X”. DA
The transition from TA 173 to COM 172 is expressed as a change from “W” or “Y” to “Z”.

The symbol column 17 in FIG.
A plurality of COMs 171 are multiplexed.
The signal format itself is the same. Each COM 172 has the same signal format, and each DATA 173 has the same signal format. However, the first and second coding rules are used in time intervals T ₁ and T ₂ . Therefore, in the multi-level code sequence 18 of FIG. 8B, the signal format of the COM 171 differs between the time sections T ₁ and T ₂ . Similarly, each COM17
2 also have different signal formats, and each DATA 173 also has a different signal format. To clarify this difference, FIG.
In (b), C coded in time intervals T ₁ and T ₂
The OM 171 is denoted by reference numerals “171 ′” and “171 ″”. Similarly, COM172
Are distinguished by reference signs “172 ′” and “172 ″”, and DATA 173 is distinguished by reference signs “173 ′” and “173 ″”.

In this embodiment, it is necessary to determine in advance how the amplitude value is assigned immediately after the coding rule is switched. In the present embodiment, immediately after switching from the first to the second encoding rule, COM
If 171 is detected, “W” is assigned and C
It is defined that "Z" is assigned when OM172 is detected. Immediately after switching from the second to the first encoding rule, it is defined that “X” is assigned when COM 171 is detected and “Z” is assigned when COM 172 is detected. You.

The transmitting end 1 must notify the receiving end 2 that the coding rule has been switched and the timing of the switching. For this purpose, in the present embodiment, the encoding unit 14 receives the COM 172 from the selector 13 and switches the encoding rule after counting four multi-level codes. In addition, the decoding unit 24
After inputting OM172 and counting four multilevel codes, the decoding rule is switched. Thereby, the encoding unit 1
4 and the decoding unit 24 synchronize the encoding rule and the decoding rule. That is, when the encoding unit 14 performs encoding according to the first encoding rule, the decoding unit 24 can perform decoding according to the first decoding rule corresponding thereto. Further, when the encoding unit 14 performs encoding according to the second encoding rule, the decoding unit 24 can perform decoding according to the second decoding rule corresponding thereto.

Next, the detailed operation of the transmitting end 1 will be described with reference to FIG. 1 and FIG. The selector 13 shown in FIG.
The symbol sequence 17 shown in (a) is output to the multi-value assignment unit 141 of the encoding unit 14. At time t _{0 to} t ₁ , COM
171 are detected periodically. Therefore, multi-level allocating section 141 alternately allocates amplitude values “W” and “Z” in this time interval according to the first encoding rule, and as a result, multi-level code sequence generating section 142 has “W” And "Z"
Code sequence 18 expressing COM 171 ′ by alternation of
Generate

Immediately after time t ₁ , multi-value assignment section 141 detects that input symbol sequence 17 has changed to DATA 173. At this time, “W” or “Z” is held in the first holding unit 15 as the previous amplitude value. However, regardless of the previous amplitude value, the multi-value allocating unit 141 allocates “X” as the current amplitude value when detecting “1”, and allocates “Y” when detecting “0”. Thereafter, the time t ₁ when DATA 173 is input is
The t _2, in the enumeration of the "X" and "Y" DATA17
The encoding unit 14 generates a multi-level code sequence 18 representing 3 ′.

In the period from t _{2 to} t ₃ , COM 171
Are periodically detected. Therefore, the encoding unit 14
As in the case of the times t _{0 to} t ₁ , the multi-level code sequence 18 expressing the COM 171 ′ by the alternation of the amplitude values “W” and “Z” is generated in this time section. However, “W” is assigned immediately after time t ₂ . Thus, as described above, a change from DATA 173 to COM 171 is expressed as a change from “X” or “Y” to “W”. As a result, the multi-level code sequence generation unit 142 generates the multi-level code sequence 18 expressing the COM 171 ′ by the alternation of “W” and “Z”.

Immediately after the time t ₃ , the multi-value assignment section 141
Detects COM 172 from the input symbol sequence 17. At this time, the first holding unit 15 holds the amplitude value “W” or “Z” assigned immediately before the time t ₃ (“Z” is shown in FIG. 8B). .).
In this case, the multi-value assignment unit 141 detects the detected COM1
The previous amplitude value “W” or “Z” is assigned to 72 as it is. As a result, from COM171 to COM17
The change to 2 is expressed. Further, the multi-value assignment unit 14
1 increments a counter (not shown) whose initial value is “0” by “1” every time an amplitude value is assigned to the detected COM 172. After time t ₃ , multi-level assignment section 141 continues to assign amplitude values according to the above-described first encoding rule. The time t _{3 when} COM 172 is detected
In t _4, "W" or "Z" is assigned alternately. Each time one of the amplitude values is assigned, the value of the counter is incremented by “1”. As a result, the multi-level code sequence generator 142 generates the multi-level code sequence 18 in which the amplitude value immediately after the time t ₃ is “Z” and the COM 171 ′ is represented by the alternation of “Z” and “W”. .

When the counter indicates "4", the multi-value allocating section 141 knows that it is time to switch the coding rule, stops using the first coding rule, and sets the second code. Start using the activation rules. Time t ₄ ~t ₅
In the example, COM 171 is periodically detected. Therefore, multi-level allocating section 141 allocates amplitude values “X” and “Z” alternately in this time interval according to the second encoding rule. However, immediately after switching from the first encoding rule to the second encoding rule, “X” is assigned as described above. As a result, in this time interval, the multi-level code sequence 18 in which the amplitude value immediately after the time t ₄ is “X” and the COM 171 ″ is represented by the alternation of “X” and “Z” is represented by the multi-level code sequence The generating unit 142 generates.

Immediately after time t ₅ , multi-value assignment section 141 detects that input symbol sequence 17 has changed to DATA 173. At this time, “X” or “Z” is held in the first holding unit 15 as the previous amplitude value. However, regardless of the previous amplitude value, the multi-value allocating unit 141 allocates “W” as the current amplitude value when detecting “1”, and allocates “Y” when detecting “0”. Thereafter, the time t ₅ when DATA 173 is input is
The t _6, in the enumeration of the "W" and "Y" DATA17
A multi-level code sequence 18 representing 3 ″ is generated by the encoding unit 14.

In the period from time t _{6 to} t ₇ , COM171
Are periodically detected. In this time interval, time t ₄
As with the t _5, the multi-level code sequence 18 representing the COM171 "by alternation of" X "and" Z "is generated. However, the amplitude value immediately after the t ₆ is" X ". Immediately after the time t ₇ , the multi-value assignment unit 141
Is detected. At this time, the multi-value assigning unit 141 assigns the amplitude value “X” or “Z” assigned immediately before time t _7.
(“Z” is shown in FIG. 8B) is directly assigned as the current amplitude value. Further, as described above, the multi-value assignment unit 141 starts counting due to the detection of the COM 172. At time t ₇ ~t ₈ which COM172 is detected, "X" or "Z" is the time allocated alternately, the counter value is incremented by "1".

Therefore, the multi-level code sequence 18 generated in this time section has the amplitude value “Z” immediately after time t ₃ , and the COM 17 is generated by the alternation of “Z” and “X”.
1 ". Further, when the counter indicates" 4 ", the multi-value allocating unit 141 knows that it is the timing to switch the coding rule, and stops using the second coding rule. Start using the one encoding rule. Thereafter, the encoding unit 14 repeats a series of operations described above,
A multi-level code sequence 18 is generated by encoding the input symbol sequence 17 according to the first or second coding rule.
This multi-level code sequence 18 is transmitted to the transmission path 3 by the transmission unit 16.

FIG. 9 shows a decoding rule preset in the decoding section 24 of the present embodiment. The decoding rule in FIG. 9 shows the previous and current amplitude values and decoded symbols. In particular, FIG. 9A shows a first decoding rule determined corresponding to the above-described first encoding rule. FIG. 9 (b)
Is the second encoding rule corresponding to the above-described second encoding rule.
Is the decoding rule. First, in order from the top of FIG.
The first decoding rule will be specifically described.

[0119] 1. When the previous amplitude value is “X” or “Y” and the current amplitude value is “W”, the decoded symbol is the reception of the COM 171. When the decoding rule is “W” immediately after the switching of the decoding rule and the decoding symbol is “W”, the decoding symbol is the reception of the COM 171. 2. If the previous amplitude value is “X” or “Y” and the current amplitude value is “Z”, the decoded symbol is COM172.
Is received. When four COM172 multi-level codes are received, the decoding rule is switched. Further, immediately after the switching of the decoding rule and when the current one is “Z”, the decoded symbol is the reception of the COM 172. Also,
When four COM-values of the COM 172 are received, the decoding rule is switched. 3. If the current amplitude value is “X”, the decoded symbol is DA
This is the reception of “1” of TA173. 4. If the current amplitude value is “Y”, the decoded symbol is DA
This is the reception of TA173 “0”. 5. If the previous amplitude value is "W" and the current amplitude value is "Z", the decoded symbol is the same as the previous decoded symbol. 6. If the previous amplitude value is "Z" and the current amplitude value is "W", the decoded symbol is the same as the previous one. 7. If the previous and current amplitude values are both "W", the decoded symbol is a change in the command symbol, that is, a change from COM171 to COM172 or COM1.
This is a change from 72 to COM171. 8. Even when the previous and current amplitude values are both “Z”, the decoded symbol is a change in the command symbol as described above.

Next, the second decoding rule will be specifically described in order from the top in FIG. 9B. 1. If the previous amplitude value is “W” or “Y” and the current amplitude value is “X”, the decoded symbol is COM171.
Is received. Also, immediately after the switching of the decoding rule, and when the current one is “X”, the decoded symbol is C
OM171 is received. 2. When the previous amplitude value is “W” or “Y” and the current amplitude value is “Z”, the decoded symbol is COM172.
Is received. When four COM172 multi-level codes are received, the decoding rule is switched. Further, immediately after the switching of the decoding rule and when the current one is “Z”, the decoded symbol is the reception of the COM 172. Also,
When four COM-values of the COM 172 are received, the decoding rule is switched. 3. When the current amplitude value is “W”, the decoded symbol is DA
This is the reception of “1” of TA173. 4. If the current amplitude value is “Y”, the decoded symbol is DA
This is the reception of TA173 “0”. 5. If the previous amplitude value is “X” and the current amplitude value is “Z”, the decoded symbol is the same as the previous decoded symbol. 6. If the previous amplitude value is "Z" and the current amplitude value is "X", the decoded symbol is the same as the previous one. 7. If the previous and current amplitude values are both “X”, the decoded symbol is a change in the command symbol, that is, a change from COM171 to COM172 or COM1.
This is a change from 72 to COM171. 8. Even when the previous and current amplitude values are both “Z”, the decoded symbol is a change in the command symbol as described above.

Next, the detailed operation of the decoding unit 24 will be described with reference to FIGS. Decoding unit 24 and the second holding portion 23, the multi-level code sequence encoded with different rules in a time interval T ₁ and T ₂ 18 (see FIG. 8 (c))
Is input through the receiving unit 21. This multi-level code sequence 18
Is accompanied by a delay Δt due to the transmission line 3 as in the other embodiments. The second holding unit 23 holds the same amplitude value as that detected by the decoding unit 24 last time. The decoding unit 24 obtains the previous amplitude value from the second holding unit 23 every time the amplitude value of the input multi-level code sequence 18 is detected, and decodes the multi-level code sequence 18 according to the decoding rule of FIG. And play. The manner of decoding and reproduction is the same as in the first embodiment,
The explanation is simplified.

What is important in the third embodiment is that the decoding unit 24 converts the portion of the signal format (the portion of the time section T ₁ ) according to the first encoding rule into the first it is decoded according to the decoding rules, and the second that of the encoding rules (part of time period T _1), is to decode according to a second decoding rule. The decoding unit 24 sets the time t ₉ to
In t _12, according to a first decoding rule (see FIG. 9 (a)), with reference to the previous amplitude value held in the second holding portion 23, COM171 included in the multi-level code sequence 18 ', D
ATA 173 'and COM 171' are decoded to obtain CO
Regenerate M171, DATA173 and COM171.

Before and after time t ₁₂ , decoding section 24 detects that amplitude value “Z” of input multi-level code sequence 18 is repeated twice. The decoding unit 24 determines the first decoding rule of 8.
, The change from COM 171 to COM 172 is detected, and the reproduction of COM 172 is started. Further, the decoding unit 24 increments a counter (not shown) whose initial value is “0” by “1” due to the start of the reproduction of the COM 172. Decoding unit 24 at time t ₁₂ ~t _13,
“Z” or “W” is detected alternately as the current amplitude value, and COM172 ′ composed of four multi-level codes is decoded with reference to the previous amplitude value “W” or “Z”, and COM1
Continue playing 72. Further, each time the decoding unit 24 detects the current amplitude value “Z” or “W”, the value of the counter is incremented by “1”. Therefore, it can be understood that the counter indicates “4” at the time when the decoding unit 24 reproduces the four multi-level codes constituting the COM 172 ′. Thereby, the decoding unit 24 knows the switching timing of the decoding rule, stops using the first decoding rule,
Start using the second decoding rule.

At time t _{13 to} t ₁₆ , the decoding unit 24 outputs the second
According to the decoding rule (see FIG. 9B), the COM 171 ″, DATA 173 ″, and COM 171 ″ included in the multi-level code sequence 18 are decoded while referring to the previous amplitude value held in the second holding unit 23. And COM171, DAT
Regenerate A173 and COM171. Before and after the time t _16, the decoding unit 24 detects that the amplitude value of the multilevel code string 18 entered "Z" is repeated twice. Decoding unit 2
4 is the second decoding rule 8. According to COM171 "
To COM 172 ", and starts reproducing the COM 172. Further, the decoding unit 24 sets the COM 1
Due to the start of reproduction of 72, the above-described counting is started. The decoding unit 24 continuously decodes the COM 172 ″ composed of four multi-level codes and continuously reproduces the COM 172 from time t _{16 to} t _{17. When} the counter indicates “4”, the decoding unit 24 , Stop using the second decoding rule and begin using the first decoding rule. Thereafter, the decoding unit 24 repeats the above-described series of operations, decodes the input multi-level code sequence 18 according to the first or second decoding rule, and reproduces a symbol.

In the above embodiment, the coding rule and the decoding rule are changed between the coding unit 14 and the decoding unit 24 as needed. This change is controlled by COM 172. Therefore, the transmission device, at each time interval T ₁ or T _2, can select the optimal encoding rules and decoding rules suitable for the surrounding environment. Also, for example, even if the multi-level code sequence 18 generated by the first coding rule cannot maintain DC balance in relation to the surrounding environment, the multi-level code sequence 18 can be changed to the second coding rule. The DC balance of the code string 18 can be improved.

In the present embodiment, only the encoding rule and the decoding rule are changed. However, the encoding unit 14
Is a quaternary code (see FIG. 2) as a first encoding rule,
Further, a ternary code (see FIG. 4) is used as a second encoding rule.
Can also be encoded. In this case, of course, the decoding unit 24 performs decoding using the first and second decoding rules shown in FIGS. In other words, the transmission device
The number of amplitude values used for encoding and decoding can be changed. For example, if the quaternary transmission is changed to the ternary transmission, the S / N ratio of the generated multi-level code sequence 18 is improved, so that the reliability of information transmission is improved. Further, when the transmission is changed from the ternary transmission to the quaternary transmission, the transmission rate of the generated multi-level code sequence 18 is improved, so that high-speed information transmission can be realized. By the way, the transmission device may transmit information having different priorities from the transmitting end 1 to the receiving end 2. In this case, the transmission device transmits the information with high priority (that is, important information) on the multi-level code sequence 18 having a small amplitude value and transmits the information with low priority (that is, information that is not so important). , Can be transmitted on the multi-level code sequence 18 of many amplitude values.

Furthermore, the transmission device may change the transmission speed (so-called baud rate). Further, in the present embodiment, the transmission device switches the coding rule and the decoding rule based on the COM 172.
However, the encoding unit 14 and the decoding unit 24 may switch between the encoding rule and the decoding rule based on a predetermined timing. Further, the transmission device can apply a combination of switching between the encoding rule and the decoding rule, switching between the number of amplitude values used for encoding and decoding, and switching between transmission speeds (baud rates).
Further, the transmission device can apply any two of the three types of switching.

(Fourth Embodiment) Although electric transmission has been described in the first to third embodiments, the present invention can be applied to optical transmission as described in the fourth embodiment. FIG. 10 is a block diagram illustrating a configuration of a transmission device according to the fourth embodiment. The transmission device of FIG. 10 differs from the transmission device of FIG.
1 and the receiving end 2 is replaced with the photoelectric conversion unit 3
2 in that it includes an optical transmission line 33 instead of the transmission line 3. Since other configurations are the same, in FIG. 10, components corresponding to the configurations in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The rules set in the encoding unit 14 and the decoding unit 24 may be any one of those already described. Therefore, in the present embodiment, the description of the encoding rule and the decoding rule is omitted.

In FIG. 10, the electro-optical converter 3 of the transmitting end 1
To 1, the multi-level code sequence generated by the coding unit 14 is input. The light-to-light conversion unit 31 performs light-to-light conversion on the input multi-level code sequence to generate an optical signal. This optical signal is emitted to the optical transmission line 33. The optical transmission path 33 transmits the input optical signal to the receiving end 2. An optical signal is incident on the photoelectric conversion unit 32 of the receiving end 2 through the optical transmission line 33. The photoelectric conversion unit 32 performs photoelectric conversion on the input optical signal, reproduces a multi-level code string, and outputs the multi-level code string to the normalization unit 22.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a block configuration of a transmission device to which a transmission method according to a first embodiment is applied.

FIG. 2 is a diagram illustrating an example of an encoding rule in quaternary transmission.

FIG. 3 is a diagram illustrating an example of a decoding rule in quaternary transmission.

FIG. 4 is a diagram illustrating an example of an encoding rule in ternary transmission.

FIG. 5 is a diagram illustrating an example of a decoding rule in ternary transmission.

FIG. 6 is a diagram illustrating an example of an encoding method in a transmission method according to the second embodiment.

FIG. 7 is a diagram showing a decoding rule corresponding to the encoding method of FIG. 6;

FIG. 8 is a diagram illustrating an example of an encoding method in a transmission method according to a third embodiment.

FIG. 9 is a diagram showing a decoding rule corresponding to the encoding method of FIG. 8;

FIG. 10 is a diagram illustrating a block configuration of a transmission device according to a fourth embodiment.

FIG. 11 is a diagram illustrating a symbol command and a data string encoded by a 4B5B encoding method.

FIG. 12 is a diagram for explaining a conventional 4B5B encoding method.

FIG. 13 is a diagram for describing a problem of the 4B5B encoding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Transmission end 13 ... Multiplexing part 14 ... Encoding part 16 ... Transmission part 2 ... Reception end 21 ... Reception part 22 ... Normalization part 24 ... Decoding part 3 ... Transmission path 31 ... Electro-optical conversion part 32 ... Photoelectric conversion part 33 … Optical transmission line

Claims (40)

[Claims] 1. A method for transmitting a multi-level code represented by a plurality of amplitude values from a transmitting end to a receiving end through a transmission path, wherein the transmitting end transmits information to be transmitted to the receiving end in the past. Encode according to the encoding rule determined based on the relationship between the generated multi-level code and the currently generated multi-level code, generate a multi-level code sequence, and transmit the generated multi-level code sequence to the transmission path. The transmitting and receiving end receives the multi-level code sequence through the transmission path, and complies with the decoding rule corresponding to the coding rule, and determines the relationship between the currently received multi-level code and the multi-level code received in the past. A transmission method for decoding a received multi-level code sequence and reproducing information based on the multi-level code sequence. 2. A transmitting end encodes information according to an encoding rule determined based on a relationship between a currently generated multi-level code and a multi-level code generated immediately before the transmitting end. 2. The transmission method according to claim 1, wherein decoding is performed based on a relationship between the multi-level code obtained and a multi-level code received immediately before the multi-level code. 3. The information includes a plurality of types of symbols, and the transmitting end encodes the plurality of types of symbols into a multi-level code having the same pattern in accordance with a coding rule to generate a multi-level code sequence. The transmission method according to claim 1, wherein in the performed multi-level code sequence, a change from a certain symbol to another symbol is expressed by a phase change of the same pattern. 4. The transmission method according to claim 1, wherein the transmitting end generates a multi-level code sequence in which the same code is not excessively continuous, and transmits the generated multi-level code sequence to a transmission path. 5. The transmission according to claim 1, wherein the transmitting end multiplexes a plurality of types of symbols as information, and encodes the multiplexed symbols according to a coding rule to generate a multi-level code sequence. Method. 6. The transmission according to claim 1, wherein the transmitting end performs encoding using the maximum and / or minimum amplitude values at least once within a predetermined time interval to generate a multi-level code sequence. Method. 7. The transmitting end and the receiving end may include:
The transmission method according to claim 1, wherein the encoding rule and the decoding rule are changed. 8. A transmitting end encodes a predetermined command as information into a multi-level code sequence, changes an encoding rule based on the command, and a receiving end reproduces the predetermined command. 2. The transmission method according to claim 1, wherein the decoding rule is changed based on the command. 9. The transmission method according to claim 1, wherein the transmitting end changes the number of amplitude values used for the multi-level code as needed. 10. A transmitting end encodes a predetermined command as information into a multi-level code string, and changes a coding rule and the number of amplitude values used for the multi-level code based on the command. The transmission method according to claim 1, wherein the receiving end reproduces a predetermined command, and changes a decoding rule and the number of amplitude values used for the multi-level code based on the command. 11. A method for optically transmitting a multilevel code represented by a plurality of amplitude values from a transmitting end to a receiving end through an optical transmission line, wherein the transmitting end transmits information to be transmitted to the receiving end, Encoding is performed according to an encoding rule determined based on a relationship between a multi-level code generated in the past and a currently generated multi-level code to generate a multi-level code sequence. Performs optical conversion to generate an optical signal, sends out the generated optical signal to an optical transmission line, and performs a photoelectric conversion on an optical signal input through the optical transmission line to generate a multi-level code sequence. And reproducing the reproduced multi-level code sequence based on the relationship between the currently reproduced multi-level code and the previously reproduced multi-level code while obeying the decoding rules corresponding to the encoding rules. , Reproducing information, transmission method. 12. A transmitting end encodes information according to an encoding rule determined based on a relationship between a currently generated multi-level code and a multi-level code generated immediately before the transmitting end.
The transmission method according to claim 11, wherein decoding is performed based on a relationship between a currently reproduced multi-level code and a multi-level code reproduced immediately before. 13. The information includes a plurality of types of symbols, and the transmitting end encodes the plurality of types of symbols into a multi-level code having the same pattern according to a coding rule to generate a multi-level code sequence. 12. The transmission method according to claim 11, wherein in the performed multi-level code sequence, a change from a certain symbol to another symbol is expressed by a phase change of the same pattern. 14. The transmission terminal according to claim 1, wherein a multi-level code sequence in which the same code is not excessively continuous is generated and transmitted to an optical transmission line.
2. The transmission method according to 1. 15. The transmission according to claim 11, wherein the transmitting end multiplexes a plurality of types of symbols as information, and encodes the multiplexed symbols according to a coding rule to generate a multi-level code sequence. Method. 16. The transmission according to claim 11, wherein the transmitting end performs encoding using the maximum and / or minimum amplitude values at least once within a predetermined time interval to generate a multi-level code sequence. Method. 17. The transmitting end and the receiving end change encoding rules and decoding rules as necessary.
Transmission method described in 1. 18. A transmitting end encodes a predetermined command as information into a multi-level code sequence, changes an encoding rule based on the command, and a receiving end reproduces the predetermined command. 12. The transmission method according to claim 11, wherein a decoding rule is changed based on the command. 19. The transmission method according to claim 11, wherein the transmitting end changes the number of amplitude values used for the multi-level code as needed. 20. The transmitting end encodes a predetermined command as information into a multi-level code sequence, and changes a coding rule and the number of amplitude values used for the multi-level code based on the command, The transmission method according to claim 11, wherein the receiving end reproduces a predetermined command, and changes the decoding rule and the number of amplitude values used for the multi-level code based on the command. 21. An apparatus for transmitting a multi-level code represented by a plurality of amplitude values from a transmitting end to a receiving end through a transmission path, wherein the transmitting end generates information to be transmitted to the receiving end in the past. An encoding unit that encodes according to an encoding rule determined based on a relationship between the multi-level code thus generated and the currently generated multi-level code to generate a multi-level code sequence, and a multi-level code generated by the encoding unit. A transmitting unit for transmitting the code sequence to the transmission path; a receiving unit for receiving the multi-level code sequence via the transmission line; and a receiving unit for receiving the multi-level code sequence received by the receiving unit in accordance with a decoding rule corresponding to the encoding rule. A transmission device including a decoding unit that decodes a multi-level code sequence received by a receiving unit and reproduces information based on a relationship between the value code and the multi-level code received by the receiving unit before. 22. An encoding unit encoding information according to an encoding rule determined based on a relationship between a currently generated multi-level code and a multi-level code generated immediately before the encoding unit. 22. The transmission apparatus according to claim 21, wherein decoding is performed based on a relationship between the multilevel code received this time and the multilevel code received immediately before by the receiving unit. 23. The information includes a plurality of types of symbols, and the encoding unit encodes the plurality of types of symbols into a multi-level code having the same pattern according to a coding rule to generate a multi-level code sequence. 22. The transmission device according to claim 21, wherein in the generated multi-level code sequence, a change from one symbol to another symbol is expressed by a phase change of the same pattern. 24. The transmission device according to claim 21, wherein the encoding unit generates a multi-level code sequence in which the same code is not excessively continuous. 25. The transmitting end further includes a multiplexing unit that multiplexes a plurality of types of symbols as information, and the encoding unit encodes the symbol multiplexed by the multiplexing unit according to an encoding rule, and Generate a value code string,
The transmission device according to claim 21. 26. The encoding unit performs encoding using the maximum and / or minimum amplitude values at least once within a predetermined time interval to generate a multi-level code sequence, and the receiving end further includes: 22. The transmission device according to claim 21, further comprising a normalization unit that normalizes the amplitude value of the multilevel coded sequence received by the unit based on the maximum and / or minimum amplitude value transmitted at a predetermined time interval. . 27. The encoding unit and the decoding unit change the encoding rule and the decoding rule as needed.
A transmission device according to claim 1. 28. An encoding unit encodes a predetermined command as information into a multi-level code sequence, changes an encoding rule based on the command, and a decoding unit reproduces the predetermined command. 22. The transmission device according to claim 21, wherein the decoding rule is changed based on the command. 29. The transmission apparatus according to claim 21, wherein the encoding unit and the decoding unit change the number of amplitude values used for the multi-level code as needed. 30. An encoding unit encodes a predetermined command as information into a multi-level code sequence, and changes a coding rule and the number of amplitude values used for the multi-level code based on the command. 22. The transmission device according to claim 21, wherein the decoding unit reproduces a predetermined command, and changes a decoding rule and the number of amplitude values used for the multi-level code based on the command. 31. An apparatus for optically transmitting a multi-level code represented by a plurality of amplitude values from a transmitting end to a receiving end through an optical transmission path, wherein the transmitting end transmits information to be transmitted to the receiving end in the past. An encoding unit that encodes according to an encoding rule determined based on a relationship between the generated multi-level code and the currently generated multi-level code to generate a multi-level code sequence, A light-to-light conversion unit that performs light-to-light conversion on the multi-level code string to generate an optical signal, and sends the light signal to the light transmission path. The reception end receives the light signal through the light transmission path, and performs photoelectric conversion. A multi-level code sequence to reproduce the multi-level code sequence, and a multi-level code reproduced by the photoelectric conversion unit this time and a multi-level code previously reproduced by the photoelectric conversion unit while complying with the decoding rule corresponding to the encoding rule. The multi-level code string reproduced by the photoelectric conversion unit is decoded based on the relationship. And a decoding device for reproducing information. 32. The encoding unit encodes information according to an encoding rule determined based on a relationship between a currently generated multi-level code and a multi-level code generated immediately before the encoding unit. 32. The transmission device according to claim 31, wherein the unit performs decoding based on a relationship between the multi-level code reproduced this time and the multi-level code reproduced immediately before by the photoelectric conversion unit. 33. The information includes a plurality of types of symbols, and the encoding unit encodes the plurality of types of symbols into a multi-level code having the same pattern according to a coding rule to generate a multi-level code sequence. 32. The transmission device according to claim 31, wherein a change from one symbol to another symbol is expressed by a phase change of the same pattern in the generated multi-level code sequence. 34. The transmission device according to claim 31, wherein the encoding unit generates a multi-level code sequence in which the same code is not excessively continuous. 35. The transmitting end includes a multiplexing unit that multiplexes a plurality of types of symbols as information, and the encoding unit encodes the symbol multiplexed by the multiplexing unit according to an encoding rule, and performs multi-level coding. Generate a code sequence,
The transmission device according to claim 31. 36. The encoding unit performs encoding using the maximum and / or minimum amplitude value at least once within a predetermined time interval to generate a multi-level code sequence. 32. The transmission device according to claim 31, further comprising a normalization unit that normalizes an amplitude value of the multi-level coded sequence received by the unit based on a maximum and / or minimum amplitude value transmitted at a predetermined time interval. . 37. The encoding unit and the decoding unit change the encoding rule and the decoding rule as necessary.
A transmission device according to claim 1. 38. An encoding unit encodes a predetermined command as information into a multi-level code string, changes an encoding rule based on the command, and a decoding unit reproduces the predetermined command. The transmission device according to claim 31, wherein the decoding rule is changed based on the command. 39. The transmission apparatus according to claim 31, wherein the encoding unit and the decoding unit change the number of amplitude values used for the multi-level code as needed. 40. An encoding unit encodes a predetermined command as information into a multi-level code sequence, and changes a coding rule and the number of amplitude values used for the multi-level code based on the command. 32. The transmission device according to claim 31, wherein the decoding unit reproduces a predetermined command and changes a decoding rule and the number of amplitude values used for the multi-level code based on the command.