JPH0650886B2 - Digital transmission circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital transmission circuit having a frame forming circuit on the transmitting side and a frame synchronizing circuit on the receiving side, and particularly, by prohibiting the insertion of regular frame bits. The present invention relates to a digital transmission circuit in which an unintentional communication state is notified from the transmitting side and the receiving side recognizes the above state due to loss of frame synchronization.

(Prior Art) Conventionally, in order to discriminate between a significant communication state and an unintentional communication state, firstly, the digital transmission circuit is normally operated only during significant communication, and the operation of the digital transmission circuit is stopped except during significant communication. Secondly, there is a known method, and secondly, a method of providing at least one bit of a signal indicating a significant communication state / involuntary communication state in the information data and mutually notifying and recognizing the state via the state display signal. It is known.

(Problems to be Solved by the Invention) Although it is possible to suppress power consumption other than during significant communication in the above-described first known technology example, some method, such as formation of a power supply path, is generated every time there is a communication request. , Or inversion, it is necessary to start the digital transmission circuit. From starting the synchronous system and equalization system to the normal operation,
It has the drawback of requiring a fairly long training period.

On the other hand, in the above-mentioned second known technology example, although the significant / unintentional state conversion has immediacy, the state indication bit must be always accessed, and therefore, the circuit is the same as that in the significant communication during the unintentional communication. Operation is required, and there is a disadvantage that the same amount of electric power is consumed in both significant and insignificant times.

The object of the present invention is to notify the significant communication state / involuntary communication state by controlling the frame configuration circuit on the transmitting side so as to prohibit the insertion of regular frame bits and displaying the frame synchronization state on the receiving side. It is another object of the present invention to provide a digital transmission circuit configured to satisfy the immediacy and low power consumption at the same time by recognizing the above drawbacks.

(Means for Solving Problems) A digital transmission circuit according to the present invention comprises a transmitting side, a receiving side, and a transmission line connecting between the transmitting side and the receiving side, and significant information data is transmitted through the transmission line. It is possible to discriminate between a significant communication state in which the transmission and reception is performed and a non-meaningful communication state in which the simple code string that does not include the significant information data is transmitted and received. The transmission side is provided with a frame configuration circuit and a selection / control means, and the reception side is provided with a frame synchronization circuit.

The frame configuration circuit is for periodically inserting one or more frame bits into the information data string to be transmitted.

The selection / control means prohibits the insertion of a regular frame bit in the unintentional communication state and forcibly removes the frame synchronization on the far-end receiving side, and notifies the significant communication state / unintentional communication state /
It is for executing recognition.

The frame synchronization circuit is for detecting frame bits that are periodically inserted to establish frame synchronization.

(Example) Next, the present invention has been described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a digital transmission circuit according to the present invention. In FIG. 1, 1 is a transmission line, 10 is a frame configuration circuit, 20 is a frame synchronization circuit, 30 is a waveform transmission circuit, 40 is a waveform reception circuit, 70 is a control unit, and 90 is a selection circuit.

In FIG. 1, the information data string to be transmitted on the signal line 50 has frame bits of a predetermined pattern periodically inserted in the frame configuration circuit 10, and is sent to the transmission line 1 by the waveform transmission circuit 30. Waveform receiving circuit 4
Received by 0.

The frame synchronization circuit 20 detects a frame bit by the received code string from the waveform receiving circuit 40 to the signal line 60,
The frame synchronization is pulled in, and the synchronization state is output by a synchronization signal on the signal line 80, for example, a logic "1" is output at the time of synchronization and a logic "0" is output at the time of asynchronous.

The control unit 70 sets the control signal on the signal line 75 to, for example, a logic “1” and outputs it during significant communication, and sets it to a logic “0” and outputs during involuntary communication.

The selection circuit 90 selects, based on the control signal on the signal line 75, to send out the code string in which the frame bits are properly inserted from the frame composing circuit 10 during significant communication, and bypasses the frame composing circuit 10 during involuntary communication. Select to transmit a code string in which no frame bit is inserted. This makes it possible to forcibly remove the frame synchronization on the receiving side placed at the remote end during involuntary communication.
Can notify significant / unwillingness.

On the other hand, on the receiving side, frame synchronization can be established by receiving a code string in which frame bits are inserted, and synchronization cannot be established by receiving a code string in which no frame bit is inserted. When the synchronization signal output on the signal line 80 is synchronous (logic “1”), it can be recognized as a significant communication state, and when asynchronous (logic “0”), it is a non-meaningful communication state. Can be recognized.

In the embodiment described above, it is clear that the presence or absence of the scrambler and the descrambler has nothing to do with it.

FIG. 2 is a block diagram showing a detailed embodiment of the selection circuit 90 in FIG.

(Effects of the Invention) As described above, according to the present invention, the transmitting side prohibits the insertion of regular frame bits during involuntary communication, forcibly removes the frame synchronization of the receiving side placed at the remote end, and By detecting the frame bit inserted synchronously and establishing frame synchronization, there is an effect that notification / recognition of the state of significant communication / involuntary communication can be easily executed by the synchronization signal of the frame synchronization circuit. Further, in the involuntary communication state, there is an effect that the minimum circuit operation is necessary, and only the pull-in period of the frame synchronization is required for the state conversion from the involuntary communication to the significant communication.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a digital transmission circuit according to the present invention. FIG. 2 is a block diagram showing a detailed embodiment of the selection circuit of FIG. 1 ... Transmission path 10 ... Frame configuration circuit 20 ... Frame synchronization circuit 30 ... Waveform transmission circuit 40 ... Waveform reception circuit 70 ... Control unit 90 ... Selection circuit 50,60.75,80 ... Signal line

Claims (1)

[Claims] 1. A significant communication state comprising a transmitting side, a receiving side, and a transmission line connecting the transmitting side and the receiving side, and transmitting and receiving significant information data through the transmission line, and the significant communication state. In a digital transmission circuit capable of distinguishing from an involuntary communication state in which a simple code string that does not include significant information data is transmitted and received, the transmitting side periodically adds one or more frame bits to an information data string to be transmitted. A frame configuration circuit for inserting, and in the involuntary communication state, prohibiting the insertion of a regular frame bit and forcibly removing the frame cycle on the far end receiving side,
A frame synchronization circuit for selecting and controlling the notification / recognition of the involuntary communication state, and for the receiving side to detect the periodically inserted frame bits and establish frame synchronization. A digital transmission circuit comprising: