JPH0442620A - Method and apparatus for coding and decoding - Google Patents

Abstract

PURPOSE:To facilitate the development of a high density digital information recorder while keeping upward compatibility with a convention information recorder by using a single decoding conversion means to decode different code signals transferred at an equal code transfer rate and provided from plural different coding means. CONSTITUTION:A single decoding conversion means A decodes different code signals transferred at an equal code transfer rate and supplied from plural different coding means. In such a coding decoding method, a single decoding conversion table or a single decoding conversion formula being a single decoding conversion means is used to select codes enabling decoding and not interfered with each other. Moreover, a coding decoding device B uses a reproduction means to reproduce medium (digital information) recorded by different coding means recorded by different coding means respectively. Thus, upward compatibility is attained to a conventional code signal at the time of decoding without providing of plural decoding theory circuits or plural decoding tables, and the development of a high density digital information recorder is easily attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a code/decoding method and apparatus, and particularly to a method and apparatus for decoding a recorded or transmitted digitally encoded signal.

[Conventional technology]

Conventionally, there have been many methods for encoding digital signals, and the present invention covers methods for decoding all of these encoded signals.

Table 1 below shows the encoding disclosed in USP 4115768 (hereinafter referred to as conventional example), and FIG.
The circuit configuration diagram configuring the conventional decoding example in the table, Figure 8 is U
FIG. 9 is a circuit configuration diagram of another conventional example disclosed in SP4463345, which is a circuit configuration diagram in which each block is decoded using a ROM conversion table. In Figures 7 to 9 of the drawings, 1 is a shift register, 2 is a logic circuit,
3 is a latch, 4 is a state memory, 5 is a ROM, and 6 is a counter.

Table 1 Data Words Code Words In order to explain the conventional example below, let us consider the 2-7 code of the conventional example, which is a recording system and whose current quantity is well known. This is shown in Table 1 above. The characteristic parameters of the codes in Table 1 are d=2°k=7. m=1. n=2. r
=3. However, here, d is each code word "
The minimum and maximum number of "0"s existing between "1" and "1", m and n respectively mean that m bits of data word are converted to n bits of code word, and r is the conversion bit length. Although there are 2-7 codes that have the same parameters as this conventional example, we will consider the most common conventional code here.

This 2-7 code decoding method is shown in the prior art example. The configuration diagram of FIG. 7 shows a generalized version of the decoding circuit. Other possible decoding methods include a method of having a state memory using a state transition diagram, as shown in Figure 8, or a method of decoding using a ROM conversion table for each block, as shown in Figure 9. It will be done.

[Problem to be solved by the invention]

As described above, as technology advances, modulation and demodulation devices are required to be faster and more dense. In response to this demand, many encoding methods suitable for higher density and higher speed have been proposed to date. However, if an attempt is made to replace the encoding method of a recording device or transmission device with a new encoding method suitable for higher density and higher speed, the signal encoded with the conventional code will be decoded with the new code as in the conventional example. Depending on the means used, it may not be possible to decode it. That is, a new decoding circuit such as the conventional example has a problem in that it cannot be made compatible with conventional codes. In addition, in order to solve these problems, it is necessary to create a device that can also decode conventionally encoded signals, that is, a device that is upwardly compatible with conventional decoding devices, and to have multiple decoding logic circuits. There is a problem in that it is necessary to switch between the two decoding tables or have multiple decoding tables and switch between them.

This invention was made to solve the above-mentioned problems, and allows different code signals transferred at the same code transfer rate and encoded by a plurality of encoding means to be decoded by a single decoding method. It is possible to achieve upward compatibility with conventional coded signals at the time of decoding without having multiple decoding theory circuits or multiple decoding tables by decoding using a conversion means, and it is possible to achieve upward compatibility with conventional coded signals at the time of decoding. The purpose of the present invention is to facilitate the development of a digital information recording device with higher density while maintaining compatibility.

[Means to solve the problem]

Therefore, in the present invention, a code decoding method is employed in which different code signals transferred at the same code transfer rate and encoded by a plurality of different coding means are decoded by a star decoding conversion means. This is what we are trying to achieve.

Further, in the above invention, the decoding conversion means is a single decoding conversion table or a single decoding conversion formula, and the code decoding method selects codes that do not interfere with each other to enable decoding. This is an attempt to achieve the previous J8 objective.

Further, in the present invention, the above-mentioned object is achieved by an encoding/decoding device comprising a reproduction means for respectively reproducing separate media recorded with different encoding means by a decoding circuit using any of the above inventions. This is what we are trying to achieve.

[Effect]

In the code/decoding method according to the present invention, a single decoding/transforming means decodes different code signals transferred at the same code transfer rate and encoded by a plurality of specific encoding means.

Further, the code decoding method in the above invention uses a single decoding conversion table or a single decoding conversion formula, which is a single decoding conversion means, to generate codes that do not interfere with each other and enable decoding. select.

Further, in the encoding/decoding apparatus of the present invention, the reproduction means reproduces media (digital information) recorded by different encoding means.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Figure 1 of the drawings is a circuit block diagram showing an embodiment of the present invention, Table 2 below is a conversion table for the ROM shown in Figure 1, Table 3 is a coding table for 3-bit and 4-bit conversion, and Figure 2 is a FIG. 3 is a conventional decoding circuit diagram, FIG. 3 is a decoding circuit diagram of this embodiment, FIGS. 4 to 6 are code set diagrams explaining the present invention in detail, and FIG. FIG. 5 is a code set diagram when the old code set and the new code set overlap, and FIG. 6 is a code set diagram when the old code set is included in the new code set.

Table 2 ROM table in Figure 1 Table 3 Table 3 Bit to 4 bit conversion table In Figure 1 of the drawing, A is a single encoding conversion means, and is a single decoding conversion table or a single decoding conversion table. It is a means for decoding different code signals that are transferred at the same code transfer rate and encoded by a plurality of different encoding means (see conventional example marked with #) (details will be described later). ). Reference numeral B designates a code/decoding device equipped with a reproducing means for reproducing media recorded by different encoding means, respectively, using a decoding circuit using the code/decoding method of the present invention. Table 3 above shows an example of coding for 3-bit to 4-bit conversion (hereinafter referred to as 3/4 code).

This embodiment will be explained below with reference to FIGS. 1 and 2 using the above-mentioned symbols 3 and 4 and the symbols 2-7 described in the conventional example.

In this embodiment, a single decoding conversion table, which is a single decoding conversion means A, is used to enable decoding (hereinafter referred to as decoding), that is, a conventional code (2-7
The explanation will be given by taking as an example a code (3/4 code) that does not interfere with each other during decoding. Although there are many codes that are more suitable for high density than the 3/4 code and do not interfere with each other during decoding, this code will be used to simplify the explanation. The feature parameters of this 3/4 code are (d, to, m, n, r) = (0, 2, 3,
4,1).

In this 3/4 code, the minimum signal interval is Tl1lIn=0.
757, so the code amount interference condition is 2-7.
Although it is more severe than the code, if this problem can be overcome, recording or transmitting at the same code transfer rate will result in T w+nd
ow is 0.5T for the 2-7 code, whereas this 3/4 code is 0.
．． Since it is 1.5 times larger than 75T, it is possible to record or transmit 1.5 times higher density data.

Therefore, the decoding of this 3/4 code will be considered as follows. As mentioned above, the 2-7 code has d=1. On the other hand, in this 3/4 code, there always exists a part in which the number of "0"s between "1"s is 1 or less in every code word. Therefore, no matter how these codewords are concatenated and no matter which part of the concatenated codewords is extracted, 2-7 in Table 1
There is no codeword pattern. Therefore, this 3/4 code can be said to be a code that does not interfere with each other during decoding compared to the conventional 2-7 code.

Originally, encoded signals recorded or transmitted using different encoding systems are processed by separate decoding means 11 and 12, as shown in FIG.
must be decrypted using However, like the 2-7 code shown here and the 3/4 code, the code transfer speeds are made equal. and select codes that do not interfere with each other during decoding. If these two conditions are given, as shown in FIG. , it becomes possible to combine.

Further, details of this embodiment will be explained using FIG. 1 and Table 2.

As mentioned above, FIG. 1 shows the circuit configuration of this embodiment, and Table 2 shows the contents of the ROM decoding conversion table in the circuit of FIG. Here, in the 3/4 code, if there are 4 bits of the code word to be converted, 3 bits of the decoded word are uniquely determined.

Since the 2-7 code is a variable length code, in order to obtain a 2-bit decoded word from a 4-bit code word, it is necessary to look at the 4-bit preceding code word and the 2-bit following code word.

Therefore, the ROM input in this case requires 10 bits.

As shown in the ROM table 8 in FIG. 1, when a 3/4 code is input, the decoded word is output in 3 bits each
If the −7 code is manually generated, the decoded word of 2-7 decoding is
Two bits are output for each four bit code word. Z is a flag for automatically identifying the 3/4 code and the 2-7 code. If the input code word is known in advance, this bit Z is not necessarily necessary.

As stated at the beginning, according to the present invention, for all recording/transmission codes, by selecting different coding systems that do not interfere with each other during decoding, it is possible to simultaneously decode different codes. The means become possible.

Therefore, for example, two codes having mutually different properties, a 2-7 code like the conventional example and an 8-bit to 10-bit conversion code like JP-A-61-92476, can be processed by a single decoding means. Can be decrypted at the same time.

Also, i! The current layer is also one of the common J8 recording methods (d, ni, m, n) = (1,2°1.2).
For an MFM code with (d, k.

RLL with properties such as m, n) - (4, 19, 2, 5)
sign, or (d, to, m, n) = (4, ω, 2.5
) and other codes useful for sample servo systems do not interfere with each other during decoding. Therefore, by using the present invention, it is possible to realize a decoding means that can decode any of these codes.

Furthermore, in the above, "do not interfere with each other during decoding"
As a condition, we have explained the case where two sets of codes do not overlap as shown in Figure 44, but as shown in Figures 5 and 6, part or all of the set of old codes is the same as the new code. The present invention can be applied to any new code that gives the same decoded result even if it overlaps a part of the code.

〔Effect of the invention〕

As explained above, in the present invention, different code signals transferred at the same code transfer rate and encoded by a plurality of specific encoding means are decoded by a single decoding conversion means, and a plurality of decoding It is possible to achieve upward compatibility with conventional encoded signals during decoding without having coding logic circuits or multiple decoding tables, thereby providing upward compatibility with conventional digital information recording devices, for example. However, there is an effect that the development of an even higher density digital information recording device can be easily achieved.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram showing one embodiment of the present invention, Fig. 2 is a conventional decoding circuit diagram, Fig. 3 is a decoding circuit diagram of this embodiment, and Figs. 4 to 6 are details of the present invention. FIG. 4 shows the case of this embodiment, FIG. 5 shows the case where the old code set and new code set overlap, and FIG. 6 shows the case where the old code set overlaps with the new code set. It is a set diagram of each code when it is included. Fig. 7 is a circuit configuration diagram configuring decoding of the conventional example shown in Table 1, Fig. 8 is a circuit configuration diagram of another conventional example, and Fig. 9 is decoding using a ROM conversion table for each block. FIG. 3 is a circuit configuration diagram. A-1 decoding conversion means B-1 code decoding device 7----shift register 8---ROM 9-1/latch 11---2-7 code decoding means 12----3/4 code Decoding means

Claims (3)

[Claims] (1) Different code signals transferred at the same code transfer rate and encoded by a plurality of different encoding means,
A code/decoding method characterized in that decoding is performed by a single decoding/transforming means. (2) A claim characterized in that the decoding conversion means is a single decoding conversion table or a single decoding conversion formula, and selects codes that do not interfere with each other to enable decoding. 1. The code/decoding method described in 1. (3) Code/decoding characterized in that the decoding circuit according to claim 1 or claim 2 is provided with a reproduction means for respectively reproducing separate media recorded by different encoding means. Device.