KR100335431B1 - Digital signal transmission method and device - Google Patents

Abstract

In the digital signal transmission method according to the present invention, a parallel digital signal of N channels is converted into a serial digital signal and then transmitted through an optical cable. The method includes generating an extra channel of the signal inverted from the signal of the first channel, which is any one of the N channels of the parallel digital signal. The generated spare channel is included in the channels of the parallel digital signal to be a second channel adjacent to the first channel. Parallel digital signals of N + 1 channels including redundant channels are converted into serial digital signals. The converted serial digital signal is converted into an optical signal. The converted optical signal is transmitted through the optical cable.

Description

Method and apparatus for transmitting digital signals

The present invention relates to a method and apparatus for transmitting a digital signal, and more particularly, to a method and apparatus for converting a parallel digital signal of N channels into a serial digital signal and then transmitting the optical signal through an optical cable.

In transmitting a digital signal over a relatively long distance, when a conventional wire cable is used, a line drop of the wire cable causes a voltage drop in the signal being transmitted, and thus line drivers are required to compensate for this. In addition, when the parallel digital signal is transmitted as it is, since a plurality of channels must be transmitted, the material of the transmission cable is used a lot. Accordingly, a method of converting a parallel digital signal into a serial digital signal and then transmitting it through an optical cable is used.

However, in the transmission of a digital signal through the optical cable as described above, the problem that the high frequency noise is frequently generated as the length of the signal level is kept constant.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for converting a parallel digital signal into a serial digital signal and then transmitting the same through an optical cable. It is to provide a method and apparatus that can cause a switchover to occur.

1 is a block diagram showing an apparatus for transmitting a digital signal according to an embodiment of the present invention.

2 is a waveform diagram showing a serial digital signal from the multiplexer of the device of FIG.

3 is a block diagram showing a transmission device when the parallel digital signal of the device of FIG. 1 is an image signal.

<Explanation of symbols for the main parts of the drawings>

1 ... personal computer, 2, 6 ... multiplexer,

3, 7 .... optical signal generator, 31, 71 ... laser driver,

32, 72 ... laser diode array, 4, 8 ... optical cable,

11, 111, 112, 113 ... inverter, 9, 12 ... clock regenerator,

CK1 ... first clock signal, CK2 ... second clock signal,

CK3 ... third clock signal, B _{N + 1} ... extra bits,

R _P , G _P , B _P ... parallel image signal, V _sync ... vertical sync signal,

H _sync ... horizontal sync signal, EN ... enable signal,

R _S , G _S , B _S ... serial image signal, Dp ... parallel digital signal,

Ds ... serial digital signal, C _SYNC ... synthetic sync signal.

The transmission method of the present invention for achieving the above object is a method of converting the parallel digital signal of the N channels to a serial digital signal, and then transmitting through an optical cable. The method includes generating an extra channel of the signal inverted from the signal of the first channel, which is any one of the N channels of the parallel digital signal. The generated spare channel is included in the channels of the parallel digital signal to be a second channel adjacent to the first channel. The parallel digital signal of the N + 1 channels including the redundant channel is converted into a serial digital signal. The converted serial digital signal is converted into an optical signal. The converted optical signal is transmitted through the optical cable.

The transmission device of the present invention for achieving the above another object is a device for converting the parallel digital signal of the N channels to a serial digital signal, and then transmitting through an optical cable. The apparatus includes an inverted pulse generator, a multiplexer, an optical signal generator and an optical cable. The inverted pulse generator generates a signal inverted from a signal of a first channel, which is any one channel among N channels of the parallel digital signal. The multiplexer includes a parallel digital signal of N + 1 channels including the redundant channel by including in the channels of the parallel digital signal such that an output terminal of the inverted pulse generator is a second channel adjacent to the first channel. Convert to a serial digital signal. The optical signal generator converts the converted serial digital signal into an optical signal. The optical cable is provided to transmit the converted optical signal.

The multiplexer of the present invention converts the parallel digital signal of the N + 1 channels including the redundant channel from the output terminal of the inverted pulse generator into a serial digital signal, so that the level of the signal to be transmitted through the optical cable is kept constant. At least one level transition may occur per frame.

Preferably, the transmission device of the present invention further includes a clock regeneration unit. The clock regeneration unit generates a clock signal having a frequency of (N + 1) / N times the frequency of the clock signal input together with the parallel digital signals of the N channels and inputs the same to the multiplexer.

The optical signal generator includes a laser driver and a laser light generator. The laser driver generates a drive signal corresponding to the serial digital signal. The laser light generation unit generates a laser light signal in response to a drive signal from the laser driver.

Hereinafter, preferred embodiments of the present invention will be described in detail.

1 shows an apparatus by a digital signal transmission method according to the present invention.

Referring to FIG. 1, an apparatus for transmitting a digital signal according to the present invention is a device for converting a parallel digital signal Dp of N channels into a serial digital signal Ds and then transmitting the same through an optical cable 4. The apparatus includes an inverting element 11, a clock regenerating portion 12, a multiplexer 2, an optical signal generating portion 3 and an optical cable 4 as an inverting pulse generating portion. The inverting element 11 is a signal of the Nth channel which is any one channel among the N channels of the parallel digital signal Dp ( B _N ) And the inverted signal ( B _{N + 1} ). The clock regeneration unit 12 has a second clock signal CK2 having a frequency of (N + 1) / N times the frequency of the first clock signal CK1 input together with the parallel digital signal Dp of the N channels. ) Is input to the multiplexer 2.

The multiplexer 2 is included in the channels of the parallel digital signal Dp such that the output terminal of the inverting element 11 becomes the N + 1 channel adjacent to the Nth channel, so that the N + 1 channels including redundant channels are included. To convert their parallel digital signals into serial digital signals (Ds). The frequency of the third clock signal CK3 used in this conversion process is N + 1 times the frequency of the input second clock signal CK2. That is, if the frequency of the first clock signal CK1 is f1 and the frequency of the third clock signal CK3 is f3, Equation 1 below is established.

The optical signal generator 3 converts the converted serial digital signal Ds and the third clock signal CK3 into optical signals. The optical signal generator 3 includes a laser driver 31 and a laser diode array 32 as a laser light generator. The laser driver 31 generates a drive signal corresponding to the serial digital signal Ds and the third clock signal CK3. The laser diode array 32 generates a laser optical signal in response to a drive signal from the laser driver 31. The generated optical signal is transmitted through the optical cable 4.

FIG. 2 shows the serial digital signal Ds from the multiplexer 2 of the device of FIG. 1. Referring to FIG. 2, in the first frame, substantial data ( B ₁ , ..., B _N ) Are all low, but the extra bit ( B _{N + 1} ) Is inverted to a high state. In the second frame, the actual data ( B ₁ , ..., B _N ), 3 bits of signals are high. Where extra bits ( B _{N + 1} ) Is the previous bit ( B _N ) Is high, so it is inverted to low. In the third frame, the actual data ( B ₁ , ..., B _N ) Are all high, but the extra bits ( B _{N + 1} ) Is reversed to the low state. As shown in the first and third frames, even if the level of the signal to be transmitted through the optical cable (4 in FIG. 1) is kept constant, at least one level change may occur per frame. As a result, it is possible to suppress the optical transmission noise generated due to the constant level of the signal.

FIG. 3 shows a transmission device when the parallel digital signal of the device of FIG. 1 is an image signal.

Referring to Fig. 3, the personal computer 1 includes each 8-bit parallel image signal ( R _P , G _P , B _P ), Vertical sync signal ( V _sync ), Horizontal sync signal ( H _sync ), Enable signal ( EN ) And the first clock signal ( CLK1 ) The inverting elements 111, 112, and 113 each comprise an 8-bit parallel image signal ( R _P , G _P , B _P ) Generates a signal of any one channel and an inverted signal, respectively. The clock regeneration unit 9 generates a second clock signal CK2 having a frequency 9/8 times the frequency of the first clock signal CK1 from the personal computer 1 and inputs it to the multiplexer 6. Let's do it. This is because the total frequency for 24 bits is converted into the frequency for 27 bits added with 3 bits.

Inside the multiplexer 6, parallel / serial shift registers and a clock multiplier are provided. Each parallel / serial shift register is input with a 9-bit parallel picture signal containing respective spare bits. The clock multiplier applies a third clock signal CK3 having a frequency nine times the frequency of the second clock signal CK2 to the parallel / serial shift registers. Accordingly, each 9-bit parallel image signal corresponds to a corresponding serial image signal ( R _S , G _S , B _S Is converted to). In addition, the input enable signal ( EN ) According to the input vertical sync signal ( V _sync ) And the horizontal sync signal ( H _sync ), So that the synthesized sync signal ( C _SYNC Output as And, the input enable signal ( EN The third clock signal CK3 is output in accordance with.

The optical signal generator 7 is a serial image signal from the multiplexer 6 ( R _S , G _S , B _S ), The composite sync signal ( C _SYNC ) And the third clock signal ( CLK3 ) Is converted into an optical signal. Here, the laser driver 71 is a serial image signal from the multiplexer 6 ( R _S , G _S , B _S ), The composite sync signal ( C _SYNC ) And the third clock signal ( CLK3 Generates driving signals corresponding to Accordingly, the laser diode array 72 generates five laser optical signals by the driving signal from the laser driver 71. Each laser light signal is transmitted via the optical cable 8 to the position of the monitor.

As described above, according to the method and apparatus for transmitting a digital signal according to the present invention, a method and apparatus for converting a parallel digital signal into a serial digital signal and then transmitting it through an optical cable, the level of the signal to be transmitted through the optical cable Even if this is kept constant, at least one level change occurs per frame, and therefore, even if the level of the digital signal is kept constant, high frequency noise generated during optical signal transmission can be suppressed.

The present invention is not limited to the above embodiments, and modifications and improvements are possible at the level of those skilled in the art.

Claims (5)

In the method of converting the parallel digital signal of the N channels into a serial digital signal, and then transmitting over an optical cable, Generating an extra channel of a signal inverted from a signal of a first channel, which is any one of N channels of the parallel digital signal; Including the generated spare channel in the channels of the parallel digital signal to be a second channel adjacent to the first channel; Converting a parallel digital signal of N + 1 channels including the redundant channel into a serial digital signal; Converting the converted serial digital signal into an optical signal; And And transmitting the converted optical signal through an optical cable. In the device for converting the parallel digital signal of the N channels into a serial digital signal, and then transmitting over an optical cable, An inversion pulse generator for generating a signal inverted from a signal of a first channel, which is any one channel among N channels of the parallel digital signal; The output terminal of the inverted pulse generator is included in the channels of the parallel digital signal such that the output channel is a second channel adjacent to the first channel, thereby converting the parallel digital signal of N + 1 channels including the redundant channel into a serial digital signal. A multiplexer for converting; An optical signal generator for converting the converted serial digital signal into an optical signal; And Optical cable transmission device comprising a; optical cable for transmitting the converted optical signal. The method of claim 2, And a clock regeneration unit for generating a clock signal having a frequency of (N + 1) / N times the frequency of the clock signal input together with the parallel digital signals of the N channels and inputting the same to the multiplexer. Device for the transmission of signals. The method of claim 2, wherein the parallel digital signal, And each of the red, green and blue image signals to be transmitted from the computer to the monitor. The method of claim 2, wherein the optical signal generation unit, A laser driver generating a driving signal corresponding to the serial digital signal; And And a laser light generator for generating a laser light signal in response to a drive signal from the laser driver.