JPS63263864A - Encoding circuit for non-isochronous signal - Google Patents

Abstract

PURPOSE:To accurately encode a non-isochronous signal, by providing a means which encodes the conversion point of the non-isochronous signal by four kinds of 2-bit codes generated by a first clock set as reference and a second clock before encoding the non-isochronous signal by a conversion point encoding method. CONSTITUTION:The group of the four kinds of 2-bit codes '10', '11' '01', and '00' generated by the first clock (a) set as reference and the second clock (b) having phase delay of 90 deg. to the clock (a) is formed. And the positions of the conversion points ex 1 and ex 2 of the non-isochronous signal nt in the groups (g), g 1, g 2,... are encoded by the 2-bit code. After that, the non- isochronous signal nt is encoded by the conversion point encoding method based on the recommendation R,111 of the CCITT. For example, a first conversion point ex 1 is encoded to '101' and a second conversion point ex 2 is encoded to '010'. Thus, since the signal is converted to a code regulated by the conversion point encoding method of the recommendation R,111 after the non- isochronous signal being encoded, accurate encoding can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a circuit for encoding a non-isochronous signal, and in particular to a circuit for encoding a non-isochronous signal according to the recommendation R of the International Telegraph and Telephone Advisory Committee.
, 111 Concerning an encoding circuit that converts to a code specified by the conversion point encoding method.

(Prior art) According to the Recommendation R.111 conversion point coding method of the International Telegraph and Telephone Consultative Committee (hereinafter referred to as CGIT'T), the sampling pulse is divided into groups of 4 bits υ1, A conversion code of 1 bit indicating the direction of polarity change and 2 bits indicating the conversion position is generated for one group located at the conversion point of the temporal signal, and is transmitted at a rate of 1 bit per 4 sampling pulses, Further, a bit indicating the polarity of the non-isochronous signal at that time is subsequently transmitted.

In addition, when one conversion point of the input non-isochronous signal is accepted by the encoding unit, reception of the next conversion point is prohibited until the conversion code is sent out, and the prohibited conversion point is used for the prohibition period. The conversion point is encoded as if it occurred at the time of the first standardized pulse immediately after the end of .

Here, a specific example of the above-mentioned R,111 transform point encoding method is as follows.
The explanation will be based on FIG. 3 and Table 1 below.

As shown in FIG. 3, the standardized pulses sp are divided into groups of four (IJl, Q2...), and where among the four sampling pulses sp within the group 01, Q2... Determine whether the isochronous signal nt is converting and the direction of polarity change at the conversion points EXI and EX2, that is, from 0 to 1, or from 1 to 0. This conversion point encoding method is expressed by one bit T1 indicating the conversion position and two bits C1 and C2 indicating the conversion position.The encoding method is shown in Table 1 below.

For example, in FIG. 3, if the non-isochronous signal nt is converted at the conversion point EXI in group q1, the bit T for the polarity change direction of the encoded signal qcd is
``1'' is entered, followed by converted image: bits C1 and C for U
2 have 11 Q II and 1 “1′, respectively.

enters. Incidentally, the bit P that follows roughly indicates the polarity of the non-isochronous signal nt, and in this case is "1".

Gaiharu. Note that the digital channel pulse dp is generated at a rate of 1 bit for every 4 sampling pulses sp.

Similarly, for the second transformation point EX2 in group q5,
As shown in Table 1, the polarity change direction pitch I-T1 is °0''.
However, the conversion position bits C11 and C21 each have QN.
, 11i11 are entered, followed by signal polarity bit P1. P
1 contains O'''.

As described above, the R,111 transform point encoding method encodes the non-isochronous signal using the transform points of (.

[Problem that the invention seeks to solve]

In the conversion point encoding method of the International Telegraph and Telephone Consultation@1 Recommendation R1111 mentioned above, if the sampling pulse and the conversion point of the non-isochronous signal occur at the same time, the conversion encoding becomes undefined and accurate encoding is not possible. The disadvantage is that it is not possible.

Specifically, as shown in FIG. 4, when the conversion point EX3 of the non-isochronous signal nt and the sampling pulse sp coincide, it becomes unclear where in the group q5 this conversion point EX3 is located, and the conversion position The disadvantage is that bits C12 and C22 are undefined.

[Means for solving problems]

The present invention is based on Recommendation R, 11 by the International Telegraph and Telephone Advisory Committee.
In a circuit that encodes a non-isochronous signal using the conversion point encoding method of No. 1, before encoding the non-isochronous signal using the conversion point encoding method, a first clock serving as a reference and, comprising means for encoding conversion points of the non-isochronous signal with four types of 2-bit codes generated by a second clock having a phase d of 90° with respect to the first clock; It is characterized by

[Effect]

Therefore, according to the present invention, the encoding of the conversion point does not become indefinite, and the non-isochronous signal can be accurately encoded.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block circuit diagram showing one embodiment of the present invention, and FIG. 2 is a time chart 11 for explaining the same.

The non-isochronous signal nt is inputted from the terminal 4, and the detection circuit 1 detects the conversion point surrounded by a chain line. The input non-isochronous signal nt via the delay circuit 7
and the delayed signal, the non-isochronous signal n
When converting t, the input signal Qnt becomes O1 as shown in Figure 2.
When converting from 1 to 1'', a pulse d at the conversion point is generated, and when converting from 1'' to 0'', a pulse e at the conversion point is generated. The gate 73 is an OR gate, and the others are inverters.

These conversion point pulses d and e cause the polarity latch circuit 8 to latch the polarity of the non-isochronous signal nt via OR gates 81 and 82, thereby generating a polarity signal 1. Note that 83 and 84 are AND gates.

The conversion point pulses d and e are a reference clock a input from terminal 5 and a reference clock a input from terminal 6.
2 of the reference clock b whose phase is delayed by 90° from
Two reference clocks a.

b makes (10), (11), (01), (00) 4
A group Q, ql, Q2. ... is held in a D-type flip-flop circuit 9.10.

The data held in the flip-flop circuits 9 and 10 is converted into a code by a code conversion circuit 11 according to the recommendation R of the International Telegraph and Telephone Advisory Committee.
, 111, and the conversion circuit 11
generates two code signals j and k.

Furthermore, the conversion point pulses d and e are generated by the select signal generation circuit 2.
It notifies that there has been a conversion, and generates select signals f, Q, and h that determine the order of codes. a3. 21 to 211 are respectively Fritbufu ■] Tubu, and 25 is an AND gate.

Further, the Noritsubu flop circuit 14 generates the polarity signal m of the non-isochronous signal nt at that time using the clock a.

The aforementioned polarity signal i, code signal j, as well as select signals f, Q, h, and second polarity signal m are input to the selector circuit 12 and encoded as specified in the aforementioned R1111 conversion point encoding method. A signal cd is sent to terminal 15. Note that the second polarity belief m is used to create a gap between the first encoding unit Cd1 and the next second encoding unit cd2 of the encoding unit @cd.

In addition, in FIG. 1, the detection circuit 3 surrounded by a chain line is
This is a circuit that detects a conversion point that occurs when acceptance of a conversion point is prohibited, and the D-shaped flip-flop circuit 13 at the lower left is a circuit that creates a time when acceptance of this conversion point is prohibited. In addition, 1 in the figure
6 is a flip 70 block, 17 is a delay circuit, 31 is an AND gate, and 32 is an exclusive OR gate.

In the embodiment shown in FIG. 1, as shown in the upper part of FIG. The four types produced are 10), (11), (01), (
00) 2-pit codes are grouped and the group Q
, 01. The conversion point ex1. of the non-isochronous signal nt within q2°... After encoding the position of ex2 with the above 2-bit code, CC
The non-isochronous signal nt can be encoded using a transform point encoding method based on ITT recommendation R6111. in particular,
As is clear from FIG. 2, the first conversion point ex1 is “
101'', and the second conversion point eX2 is '010'.
” is encoded.

〔Effect of the invention〕

As explained above, the present invention includes a reference clock,
(10), (11), (01), (00
), the non-isochronous signal is encoded and then converted to the code specified by the R,111 transform point encoding method, which has the effect of accurately encoding without indeterminacy. That is, according to the present invention, a non-isochronous signal is converted into a code specified in the conversion point coding method of International Telegraph and Telephone Advisory Committee Recommendation R, 111.
It has the effect of allowing accurate conversion.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a time chart showing the same operation, and FIG.
The figure is a time chart for explaining the same as above, and FIG. 4 is a time chart for explaining the conventional example. DESCRIPTION OF SYMBOLS 1... Conversion point detection circuit, 2... Select signal generation circuit, 3... Conversion point detection circuit when conversion point reception is prohibited, 4.5, 6
．． 15...terminal, 7...delay circuit, 8...non-isochronous signal polarity latch circuit, 9.10.13
．． 14...Flip 70 tube, 11...Code conversion circuit, 12...Selector circuit.

Claims (1)

[Claims] Recommendation R. by the International Telegraph and Telephone Advisory Committee. In a circuit that encodes a non-isochronous signal by the conversion point encoding method of No. 111, before encoding the non-isochronous signal by the conversion point encoding method, the reference first clock and the The invention is characterized by comprising means for encoding conversion points of the non-isochronous signal with four types of 2-bit codes generated by a second clock having a phase delay of 90 degrees with respect to the first clock. A coding circuit for non-isochronous signals.