JP2616409B2 - Pointer processing circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pointer processing circuit, and more particularly to pointer processing for a channel signal in a multiplex signal.

[0002]

2. Description of the Related Art Generally, pointer processing for a channel signal in a multiplex signal is performed, for example, according to CCITT Recommendation G. 707, G.R. 708, and G.R. 709 or ITU-T Recommendations G.707, G.708, and G.70
9

Here, a conventional pointer processing circuit will be described with reference to FIG.

The illustrated pointer processing circuit includes first to n-th pointer processing units 11 to 1n (n is an integer of 2 or more). The multiplex signal comprises first to nth channel signals, wherein the first and nth channel signals have at least data and pointer values. First to n-th channel signals are supplied to the first to n-th pointer processing units 11 to 1n, respectively. The first pointer processing unit 11 includes a pointer detection circuit 21, a stuff processing circuit 22, a selection circuit 23, a phase counter 24, and a comparison circuit 25, and the second to n-th pointer processing units 12 to 1n also have the first
The same components as those of the pointer processing unit 11 are provided.

Here, the operation of the first pointer processing unit 11 will be described with reference to FIG. As described above, the first pointer processing unit 11 supplies the first channel signal (FIG.
(A)) is given. The first channel signal has a plurality of time slots. For example, a pointer value 104 is added before the i-th time slot, and a non-data area 300 and a negative stuff A time slot 301 and a main staff time slot 302 are located. The pointer value in the data is detected by the pointer detection circuit 21 and output as a detection pointer.
Given to. The stuff processing circuit 22 compares the detected pointer value of the previous frame with the detected pointer value of the current frame, performs pointer processing based on a predetermined rule, and determines whether or not stuff execution is being performed. That is, the stuff processing circuit 22 detects the stuff state and transmits a stuff detection signal according to the detection result (FIG. 4B). Code “0” in the stuff detection signal
Indicates non-stuff, sign “+” indicates positive stuff, and sign “−” indicates negative stuff. Further, the stuff processing circuit 22 generates a comparison pointer by stuff processing (FIG. 4).
(C)).

As shown in the figure, a clock generation circuit 23 is connected to the first pointer processing section 11, and the clock generation circuit 23 is supplied with a continuous clock signal CLK and a plurality of timing signals. The clock generation circuit 23 responds to the timing signal according to the non-stuff clock signal (FIG. 4D), the negative stuff clock signal (FIG. 4E), and the positive stuff clock signal (FIG. 4F). )) Is output. The non-stuff clock signal, the negative stuff clock signal, and the positive stuff clock signal are supplied to the selection circuit 24. The selection circuit 24 selects one of the non-stuff clock signal, the negative stuff clock signal, and the positive stuff clock signal according to the stuff indicated by the stuff detection signal, and selects the selected clock signal (FIG. 4).
(G)) is given to the phase counter 25.

The phase counter 25 counts according to the selected clock signal, and compares the count value, that is, the stuff pointer offset value (FIG. 4 (h)) with a comparison circuit 26.
Give to. The comparison circuit 26 is provided with a comparison pointer value from the stuff processing circuit 22. The comparison circuit 26 compares the pointer offset value with the comparison pointer value, and when these values match, a data head instruction signal (FIG.
(I) is output.

The second to n-th pointer processing units 12
Also, as shown in FIG.
The clock generation circuit 23 is connected to the second to n-th pointer processing units 12 to 1n.

[0009]

As described above, in the conventional pointer processing circuit, it is necessary to provide a phase counter for each channel because the stuffing state is determined for each channel signal and the stuffing process is performed for each channel signal. However, as a result, there is a problem that the circuit scale increases when the number of channels increases.

An object of the present invention is to provide a pointer processing circuit having a small circuit size.

[0011]

According to the present invention, there is provided a pointer processing circuit for receiving a multiplexed signal in which a plurality of channel signals are multiplexed and processing a pointer included in the channel signal for each of the channel signals. Pointer detection means for receiving the channel signal, detecting the pointer and transmitting a detected pointer value; counter means for counting a pointer offset value common to each of the channel signals and transmitting the offset value as an offset count value; A comparison means for comparing and judging a value and the offset count value and outputting a data head position signal in the non-stuff state as a non-stuff state data head position signal; and a non-stuff state data head position signal and the offset count value. Based on the data head position signal and Pulse generating means for generating a data head position signal in the stuff state as a positive stuff state data head position signal and a negative stuff state data head position signal, and a stuff for performing a stuff determination according to the detected pointer value and outputting a stuff instruction signal Processing means for selectively outputting the non-stuff state data head position signal, the positive stuff state data head position signal, and the negative stuff state data head position signal as an output data head position signal in response to the stuff instruction signal. And a pointer processing circuit characterized by having a selection means.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

Referring to FIG. 1, the illustrated pointer processing circuit includes first to n-th pointer processing units 31 to 3n (the pointer processing unit shown in FIG. 1 is different from the pointer processing unit shown in FIG. 3). Its configuration is different). The first to n-th pointer processing units 31 to 3n respectively have first to n-th pointer processing units.
Are provided. First pointer processing unit 3
1 includes a pointer detection circuit 21, a stuff processing circuit 22, a comparison circuit 41, a pulse generation circuit 42, and a selection circuit 43, and includes second to n-th pointer processing units 32 to 3.
n (the second pointer processing unit 32 is not shown) has the same components as the first pointer processing unit 31. Then, the first to n-th pointer processing units 31 to 3
A phase counter 44 is connected to n.

The operation of the first pointer processing unit 31 will now be described with reference to FIG. As described above, the first channel signal is supplied to the first pointer processing unit 11 (FIG. 2A). Note that the pointer value 104 is not shown in FIG. Pointer detection circuit 21
Then, a pointer value 104 indicating a data head position and a stuff state at the time of stuff is detected from the first channel signal, and the detected pointer value is sent to the stuff processing circuit 22 and the comparison circuit 41.

The phase counter 44 receives a predetermined clock signal and outputs a unique pointer offset value common to each channel. That is, the phase counter 44 counts the clock signal and outputs the count value as a pointer offset value (FIG. 2B). Then, the pointer offset value is given to the comparison circuit 41.
The comparison circuit 34 compares the detection pointer with the pointer offset value and outputs a data head pulse in the non-stuff state (non-stuff state data head pulse) (FIG. 2).
(C)).

The pulse generation circuit 42 is provided with a pointer offset value and a head pulse of non-stuff state data.
From the pointer offset value and the non-stuff state data head pulse, the data head pulse in the positive stuff state (positive stuff state data head pulse) shown in FIG. 2D and the data head pulse in the negative stuff state shown in FIG. A negative stuff state data head pulse is generated, and the positive stuff state data head pulse and the negative stuff state data head pulse are supplied to the selection circuit 43. The selection circuit 43 is supplied with the non-stuff state data head pulse from the comparison circuit 41.

On the other hand, the stuff processing circuit 22 determines whether the stuff state is positive stuff, negative stuff, or non-stuff based on the detected pointer, and outputs the result as a stuff instruction signal (FIG. 2 (f)). )). In this embodiment, in the stuff detection signal, code “0” indicates non-stuff, code “1” indicates positive stuff, and code “2” indicates negative stuff.

The selection circuit 43 selects any one of the head pulse of the non-stuff state data, the head pulse of the positive stuff state data, and the head pulse of the negative stuff state data in accordance with the stuff instruction signal and outputs it as the data head signal ( FIG. 2 (g)).

The second to n-th pointer processing units 32
Since the same operation as that of the first pointer processing unit 31 is performed in the steps 3 to 3n, the description is omitted here.

In the above-described embodiment, the pointer offset value for the positive stuff with respect to the pointer offset value is "+1", and the pointer offset value for the negative stuff is "-".
Although the value is set to "1", the pointer offset value for the positive stuff or the negative stuff may be set as appropriate in accordance with the allowable number of stuffs per frame. Although “level” is output, it can be set as appropriate according to the application.

Note that the pulse generation circuit responds to the non-stuff state data head position signal which is the reference phase by, for example,
Since only "+1" or "-1" is used, the circuit scale is extremely small, and the power consumption is extremely small.

[0022]

As described above, in the present invention, one phase counter is shared by all the channels, so that even if the multiplicity is large, the circuit scale does not increase and the power consumption can be reduced. effective.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a pointer processing circuit according to the present invention.

FIG. 2 is a time chart for explaining an operation of the pointer processing circuit shown in FIG. 1;

FIG. 3 is a block diagram showing a conventional pointer processing circuit.

FIG. 4 is a time chart for explaining an operation of the pointer processing circuit shown in FIG. 3;

[Explanation of symbols]

 11 to 1n pointer processing unit 21 pointer detection circuit 22 stuff processing circuit 23 clock generation circuit 24, 43 selection circuit 25, 44 phase counter 26, 41 comparison circuit 31 to 3n pointer processing unit 42 pulse generation circuit

Claims (1)

(57) [Claims] 1. A pointer processing circuit for receiving a multiplexed signal obtained by multiplexing a plurality of channel signals and processing a pointer included in the channel signal for each channel signal, wherein the pointer processing circuit detects the pointer upon receiving the channel signal. Pointer detection means for transmitting a detected pointer value, and counter means for counting a pointer offset value common to each of the channel signals and transmitting it as an offset count value, and comparing and determining the detected pointer value with the offset count value. Comparing means for outputting the data head position signal in the non-stuff state as a non-stuff state data head position signal, and a data head position signal in the normal stuff state based on the non-stuff state data head position signal and the offset count value. Data head position signal in negative stuff state Pulse generation means for generating a signal as a positive stuff state data head position signal and a negative stuff state data head position signal, a stuff processing means for making a stuff determination according to the pointer detection value and outputting a stuff instruction signal, Selecting means for selectively outputting the non-stuff state data head position signal, the positive stuff state data head position signal, and the negative stuff state data head position signal in response to an instruction signal as an output data head position signal. A pointer processing circuit.