TWI501084B - Computer signal transmission system, kvm extender and method of data transmission - Google Patents

Description

Computer signal transmission system, keyboard-image-mouse extension system and data transmission method

The invention relates to a computer signal transmission system and a data transmission method, in particular to a computer signal transmission system and a data transmission method capable of automatically adjusting a signal transmission rate.

In the conventional remote control system, the transmission line connecting the transmitting end and the receiving end often limits the quality of the transmitted signal. It is well known that when a signal is transmitted in a transmission line, if the length of the transmission line is too long, the inherent resistance of the transmission line and the formed capacitance may affect the original signal, resulting in signal attenuation, distortion, and easy interference, when the receiving end receives the signal and performs data. When data recovery is performed, the error rate of the data is increased and may not be restored to the original correct data. Moreover, error correction of a large number of erroneous transmission signals by the receiving end consumes a large amount of system resources, which may result in transmission interruption due to failure to cooperate with the transmitting end. On the other hand, if the data is transmitted at a low speed only for the receiving capability of the signal receiving end, the efficiency of the transmission may be poor and the overall performance may be affected.

U.S. Patent No. 5,862,141 discloses a microwave communication system for adjusting the transmission rate of a signal by calculating the error rate of data received at the receiving end in a wireless transmission environment. If the data error rate is higher than an upper threshold, the transmission rate is lowered; otherwise, if the data error rate is lower than the lower threshold, the transmission rate is increased. The microwave communication system ensures the correctness of data restoration by dynamically adjusting the transmission rate.

However, the above transmission method still has a situation in which data restoration occurs at the receiving end of the data. Therefore, the use of transmission lines for data transmission still requires an effective technical solution to meet the needs of correctly transmitting data in response to the length of the transmission line. Therefore, it is necessary to propose a method that can balance the overall performance and the correctness of the data at the receiving end.

It is an object of the present invention to provide a computer signal transmission system, a keyboard-video-mouse extension system (KVM extender), and a data transmission method.

Another object of the present invention is to maintain the stability of data transmission and to improve the transmission interruption or transmission failure caused by high data error rate caused by transmission signal attenuation and distortion.

Another object of the present invention is to improve the versatility and adaptability of the product.

According to the above object of the present invention, the present invention provides a computer signal transmission system including a first module and a second module, wherein the first module and the second module are connected to each other by a transmission line, wherein the first module is at least The method includes: a line length detector for detecting the length of a transmission line; and a central controller coupled to the line length detector for setting a transmission rate according to the length of the transmission line detected by the line length detector; And a transmission rate generating unit that receives the transmission rate set by the central controller, and transmits the data to the second module at the transmission rate.

The present invention further provides a keyboard-image-mouse extension system, comprising: a first module connected to a computer host; and a second module coupled to the first module via a transmission line, the second module And connected to a display and a universal serial bus (USB) device, wherein the first module further comprises: a first converter, converting one single-ended image signal of the host computer output into one a differential image signal; a first USB interface for connecting to a USB port of the computer host; a first encoder/decoder for transmitting the host computer to the first USB signal of the USB device for encoding to obtain a a second USB signal; and a first transceiver for transmitting the second USB signal, wherein the second module further comprises: a second converter, converting the differential image signal into a single-ended image signal, and outputting a second USB interface for connecting to the USB device; a second transceiver coupled to the first transceiver for receiving the second USB signal; and a second encoder/decoder for Two USB signals for solution To obtain a third USB signal, and wherein the first module and second module each have a transmission rate logic unit for adjusting the transmission rate of the second USB signal depending on the length of the transmission line.

The invention further provides a keyboard-image-mouse extension system, comprising at least: a first module connected to a computer host and a first USB device; and a second module via a transmission line and the first module The second module is coupled to a display and a second USB device, wherein the first module further comprises: a first converter for converting a single-ended image signal outputted by the host computer into a differential image a first USB interface for connecting the first USB device; a first encoder/decoder for transmitting the first USB device to the first USB signal of the second USB device for encoding to obtain a second a USB signal; and a first transceiver for transmitting the second USB signal, wherein the second module further comprises: a second converter, converting the differential image signal into a single-ended image signal, and outputting to the display a second USB interface for connecting the second USB device; a second transceiver coupled to the first transceiver for receiving the second USB signal; and a second encoder/decoder for Two USB signals are decoded to get a third The USB signal, wherein the first module and the second module each have a transmission rate logic unit for adjusting the transmission rate of the second USB signal according to the length of the transmission line.

The invention also provides a data transmission method, comprising the steps of: (1) providing a transmission line for connecting a first module and a second module; (2) detecting the length of the transmission line; and (3) detecting the transmission line; The length of the transmission line, which sets a transmission rate; and (4) when the data is transmitted within the transmission line, the data is transmitted at the transmission rate.

The invention can adjust the transmission rate of the data between the two according to the length of the transmission line connected to the first module and the second module, and realize the dynamic equalization of the transmission rate and the length of the transmission line. When the length of the transmission line is relatively long, low-rate transmission is adopted, and the transmission line length is relatively short, and high-rate transmission is adopted, so that not only the stability of data transmission can be maintained, but also the high data error rate due to attenuation and distortion of the transmission signal is improved. Causes a transmission interruption or transmission failure, while getting the highest rate of data transmission.

Please refer to FIG. 1, which shows a functional block diagram of a computer signal transmission system 20 implemented in accordance with the present invention. The computer signal transmission system 20 of the present invention includes a first module 21 and a second module 22. The first module 21 and the second module 22 are connected to each other by a transmission line 23, and the data and signals are transmitted through the transmission line 23. transmission. The first module 21 and the second module 22 respectively have transceivers 214, 224 for transmitting and receiving data. For example, when the first module 21 is the transmitting end and the second module 22 is the receiving end, the first module 21 transmits the data to the transceiver 224 through the transceiver 214, and is received by the second module 22. On the other hand, when the second module 22 is the transmitting end and the first module 21 is the receiving end, the second module 22 transmits the data to the transceiver 214 through the transceiver 224, and is received by the first module 21. Before the data transmission, the first module 21 and the second module 22 first detect the length of the transmission line 23, and adjust the transmission rate of the data according to the length of the detected transmission line 23.

As shown in FIG. 1, the first module 21 and the second module 22 respectively have line length detectors 212, 222. When the first module 21 is a transmitting end, before detecting the data transmission, in order to detect the length of the transmission line 23 and obtain the corresponding maximum transmission rate, the line length detector 212 of the first module 21 sends a first packet to The line length detector 222 of the second module 22 is configured to be transmitted by the transceiver 214 of the first module 21, transmitted in the transmission line 23, and received by the transceiver 224 of the second module 22. The line length detector 222 of the second module 22 immediately returns a second packet to the line length detector 212 of the first module 21 along the opposite path. The line length detector 212 of the first module 21 multiplies half of the time difference by the transmission rate of the packet according to the time of sending the first packet and the time of receiving the second packet, thereby obtaining the transmission line. The length of 23. On the other hand, when the second module 22 is a transmitting end, the line length detector 222 of the second module 22 can detect the length of the transmission line 23 in a similar manner before data transmission.

As shown in FIG. 1 , the first module 21 has a central controller 215 coupled to the line length detector 212 and a transmission rate generating unit 219 coupled to the central controller 215 . When the first module 21 is a transmitting end, when the data is transmitted, the central controller 215 of the first module 21 sets a transmission rate according to the length of the transmission line 23 detected by the line length detector 212, and notifies The second module 22 will transmit the data at the set transmission rate. The relationship between the transmission rate set by the central controller 215 and the length of the transmission line 23 may be a linear relationship or a non-linear relationship, but when the length of the transmission line 23 is longer, it should be set to a lower transmission rate, and the length of the transmission line 23 is shorter. It should be set to a higher transmission rate to ensure that the data can cooperate with the second module 22 during the transmission process, and the transmission interruption or the data transmission failure and the data restoration error occur. The transmission rate generating unit 219 of the first module 21 receives the transmission rate set by the central controller 215, and adjusts the transmission rate of the data to the transmission rate set by the central controller 215, and transmits the data to the transmission rate according to the transmission rate. Two modules 22. Similarly, the second module 22 has a central controller 225 coupled to the line length detector 222 and a transmission rate generating unit 229 coupled to the central controller 225. When the second module 22 is a transmitting end, the central controller 225 and the transmission rate generating unit 229 of the second module 22 set the transmission rate in a manner similar to that of the first module 21 when performing data transmission. The transmission rate transmits the data to the first module 21.

Please refer to FIG. 1 and FIG. 3 . In an embodiment, when the first module 21 is a transmitting end, the central controller 215 of the first module 21 is configured according to the transmission line 23 detected by the line length detector 212. The length, and an upper limit of the transmission rate is set against the line length and transmission rate upper limit table as shown in Fig. 3, while notifying the second module 22 that the data will be transmitted at a rate close to but not exceeding the upper limit of the transmission rate. When the transmission line is generally produced in the industry, there are some specifications of specific length (such as 300 ft, 700 ft, 100 ft, etc.). The upper limit of the line length and the transmission rate shown in FIG. 3 is the empirical value obtained by the experimental test. A memory 216 can be configured in the first module 21, and the line length and the upper limit of the transmission rate are stored in advance. For the central controller 215 to access. During the experimental test, 12 lengths of 300, 620, 700, ..., 1040 feet (ft) are selected for testing. When the length of the transmission line is less than or equal to 300 feet, the upper limit of the preferred transmission rate is 40 Mbps. When the transmission line length is 620 feet, the upper limit of the preferred transmission rate is 32 Mbps; and so on, when the transmission line length is 1040 feet, the upper limit of the preferred transmission rate is 10.7 Mbps. Therefore, when the length of the transmission line 23 detected by the line length detector 212 of the first module 21 is less than or equal to 300 feet, the central controller 215 sets the upper limit of the transmission rate to 40 Mbps; when the detected transmission line 23 When the length is between 300 and 620 feet, the upper limit of the transmission rate is set to 32 Mbps; and so on, when the length of the detected transmission line 23 is between 1000 and 1040 feet, the upper limit of the transmission rate is set to 10.7 Mbps. If the length of the transmission line 23 is more than 1040 feet, the upper limit of the transmission rate is 10.7 Mbps. On the other hand, in the case where the second module 22 is the transmitting end, similarly, a memory 226 can be disposed in the second module 22, and the central controller 225 of the second module 22 is stored in the memory 226 and the foregoing. The upper limit of the transmission rate is set in the same manner as described above, and is not described here.

Please refer to Figures 1, 2 and 3, and Figure 2 shows the transmission rate generating units 219, 229 as shown in Figure 1. The transmission rate generating unit 219 of the first module 21 and the transmission rate generating unit 229 of the second module 22 respectively include a first transmission rate logic subunit 2191, 2291, and a second transmission rate logic subunit 2192, 2292, respectively. The 12th transmission rate logic subunits 2193, 2293 and the like have twelve levels of modulation logic, and respectively have selection switches 2190, 2290. The twelve-level modulation logic of the transmission rate generating units 219, 229 is set according to the line length and transmission rate upper limit table shown in FIG. 3, and each transmission rate logic sub-unit corresponds to a transmission rate upper limit. When the data transmission is performed, when the first module 21 is the transmitting end or the second module 22 is the transmitting end, the transmission rate generating units 219 and 229 may perform the transmission determined by the first module 21 and the second module 22. Rate upper limit, selecting a transmission rate logic sub-unit corresponding to the upper limit of the transmission rate by selecting switches 2190, 2290, respectively, to adjust the rate of data transmission to be close to but not exceeding the upper limit of the transmission rate to approach but not exceed the transmission rate The rate of the upper limit is transmitted. For example, when the length of the detected transmission line 23 is 600 feet, the upper limit of the transmission rate is set to 32 Mbps according to the line length and transmission rate upper limit table shown in FIG. 3, and the second transmission rate logic subunit 2192 Corresponding to, 2292, the transmission rate generating unit 219 of the first module 21 and the transmission rate generating unit 229 of the second module 22 respectively pass the selection switches 2190, 2290 to respectively select the respective second transmission rate logic subunits 2192, 2292. Thereby, the rate of data transmission is adjusted to be close to but not exceeding 32 Mbps.

Since the computer signal transmission system 20 of the present invention can adjust the transmission rate of data between the two according to the length of the transmission line 23 connected to the first module 21 and the second module 22, when the length of the transmission line 23 is relatively long, Set a lower transmission rate, and set a higher transmission rate when the length of the transmission line 23 is relatively short, so that the stability of the data transmission can be maintained, and the high data error rate caused by the attenuation and distortion of the transmission signal is improved to cause the transmission interruption. Or the case where the transmission failed.

In the computer signal transmission system 20 of the present invention, the line length detector 212 and the transmission rate generating unit 219 of the first module 21 (or the line length detector 222 and the transmission rate generating unit 229 of the second module 22) may Field-programmable Gate Array (FPGA), Programmable Logic Device (PLD), Programmable Array Logic (PAL), Generic Array (Generic Array) Logic, GAL), Complex Programmable Logic Element (CPLD), or Special Application Integrated Circuit (ASIC), or implemented in hardware, firmware, integrated circuits, or mounted with detected transmission line lengths and The hardware or firmware of the application that adjusts the transmission rate according to the length of the transmission line. In the present invention, the transceivers 214, 224 of the first module 21 and the second module 22 can be implemented by an RS485 transceiver, and can be used as a transmission line 23 by using a fifth type of CAT-5 network cable. Serial transmission.

The first module 21 and the second module 22 of the computer signal transmission system 20 of the present invention can be applied as a local unit and a remote unit of a keyboard-video-mouse extension device (KVM extender). ), or the application is a computer-side adapter (dongle) and a keyboard-video-mouse switching device (KVM switch) to realize the stability of data transmission under the environment of long-distance transmission using a transmission line.

Please refer to FIG. 4a, which shows a functional block diagram of a keyboard-image-zoom extension system (KVM extender) implemented in accordance with the present invention. The keyboard-image-mouse extension system of the present invention includes a local end unit 51 and a remote unit 52, both of which are connected by a transmission line 53 (e.g., a fifth type of network cable). The local end unit 51 is connected to a computer host to transmit the image signals (RGB and sync signals) output by the host computer to the remote screen. In addition to connecting the screen, the remote unit 52 is connected to a keyboard and a mouse. To transmit a control signal representing the operation of the mouse or the keyboard to the host computer at the other end. Moreover, the local end unit 51 is also connected to a data port of the computer host, such as a USB port, and the remote unit 52 is also connected to a USB Mass Storage Device, such as a flash drive, a finger disc, and an external connection. The hard disk or the like, the computer host and a large amount of data storage connected to the remote unit 52 can transfer and store data to each other. In an embodiment, the local end unit 51 can also connect a large amount of data storage such as a flash drive, a finger disc, and an external hard disk, and the various data storage devices connected to the local end unit 51 and the remote unit 52 are connected to each other. Access to data is possible. In addition, please refer to FIG. 4b. In the remote control of multiple computers, a keyboard-image-sliding is placed between the local end unit 51 and the remote unit 52 of the keyboard-image-mouse extension system. The mouse switches the device 54, so that the user can remotely control at least two computers on the local end.

Please refer to FIG. 5 and FIG. 6 for the local end unit 51 and the remote unit 52 of the keyboard-image-mouse extension system in FIGS. 4a and 4b, respectively. Before transmitting data (such as USB related data), the local end unit 51 and the remote unit 52 can detect the length of the transmission line 53 by transmitting a packet or a signal having a specific waveform to each other. The local end unit 51 and the remote unit 52 respectively have RS485 transceivers 514, 524 (which can be implemented on a chip of the type ADM485) for transmitting and receiving data. As shown in FIG. 5, the local end unit 51 has a central controller 515 connected to a data connection port (such as a USB port) of the computer host, or connected to a large data storage device via the USB interface 5501. The data is transmitted in compliance with the USB standard by a USB Host Controller 550. As shown in FIG. 6, the remote unit 52 has a central controller 525 (which can be implemented as a W90N740 chip) connected to a mass data storage via a USB interface 5601, and is provided with a USB host controller 560. The central controller 515 of the local end unit 51 and the central controller 525 of the remote unit 52 set a transmission rate according to the length of the detected transmission line 53, or in an embodiment, according to the detected transmission line 53 The length is set according to the line length and transmission rate upper limit table shown in FIG.

As shown in FIG. 5 and FIG. 6, the local end unit 51 and the remote unit 52 respectively have an FPGA 511 and an FPGA 521, and the transmission rate logic units 519 and 529 and the first encoding/decoding are respectively disposed in the FPGAs 511 and 521. The 510 and the second encoder/decoder 520. The transmission rate logic units 519, 529 receive the transmission rate or the transmission rate upper limit set by the central controller 515, 525, and adjust the transmission rate of the data according to the transmission rate or the transmission rate upper limit. When the local end unit 51 is to transmit a first USB signal from the computer host or a large amount of data storage connected through the USB interface 5501 to a large amount of data storage connected to the remote unit 52 through the USB interface 5601, the first USB The signal is first encoded by the first encoder/decoder 510 of the local end unit 51 to obtain a second USB signal, which may include a Manchester Encoding mode. The second USB signal is transmitted by RS485 transceiver 514 and received by RS485 transceiver 524 of remote unit 52. The second USB signal is then decoded via the second encoder/decoder 520 of the remote unit 52 to obtain a third USB signal, and finally the third USB signal is transmitted to a plurality of data stores connected to the remote unit 52. Complete the transfer of the data. On the other hand, when the remote unit 52 wants to transmit a fourth USB signal of a large amount of data storage connected through the USB interface 5601 to a computer host connected to the local end unit 51 or a large amount of data connected to the local end unit 51 through the USB interface 5501. In the storage, the fourth USB signal is first encoded by the second encoder/decoder 520 of the remote unit 52 to obtain a fifth USB signal; likewise, the encoding method may include the Manchester encoding mode. The fifth USB signal is transmitted by RS485 transceiver 524 and received by RS485 transceiver 514 of local end unit 51. The fifth USB signal is further decoded by the first encoder/decoder 510 of the local end unit 51 to obtain a sixth USB signal, and finally the sixth USB signal is transmitted to the host computer or a large amount of data connected to the local end unit 51. The storage is used to complete the transfer of the data. The second USB signal and the fifth USB signal are transmitted between the RS485 transceiver 514 and the RS485 transceiver 524 at the transmission rate or at a rate close to but not exceeding the upper limit of the transmission rate.

Please refer to FIG. 5, FIG. 6 and FIG. 7 at the same time, wherein FIG. 7 shows a schematic diagram of the keyboard-image-mouse extension system of the present invention adjusting the transmission rate according to the length of the transmission line. If the transmission line length is 1040 feet, the transmission rate logic units 519, 529 of the FPGA 511, 521 will reduce the transmission rate of 40 Mbps (or the signal width of 25 ns in the figure) to 10 Mbps (or 100 ns signal width as shown). ), or reduce the transmission rate to a transmission rate upper limit close to but not exceeding 10.7 Mbps according to the line length and transmission rate upper limit table shown in FIG. 3, at a transmission rate of 10 Mbps or a transmission rate upper limit close to but not exceeding 10.7 Mbps. Data is transmitted through RS485 transceivers 514, 524.

In the keyboard-image-sliding extension system of the present invention, the FPGAs 511 and 521 in the local end unit 51 and the remote unit 52 can be replaced by the following components, such as a programmable logic device (PLD) and a programmable array logic ( PAL), General Logic Array (GAL), Complex Programmable Logic Element (CPLD), or Special Application Integrated Circuit (ASIC). Alternatively, the FPGAs 511 and 521 are replaced by hardware or firmware implemented in hardware, firmware, integrated circuits, or an application having the function of detecting the length of the transmission line and adjusting the transmission rate according to the length of the transmission line. In addition, the FPGA 511 in the local end unit 51 can be implemented as a wafer of the type PDK82C12.

Referring to FIG. 5 and FIG. 6 , the keyboard-image-mouse extension system of the present invention converts a single-end image signal outputted by a host computer into a differential image signal to a differential image signal. The transmission is performed, and finally the differential image signal is converted into a single-ended image signal output to the far-end screen. As shown in FIG. 5, the DB-15 port of the host computer outputs a video graphics array (VGA) signal (which is a single-ended video signal) to the local end unit 51, and includes three primary color signals (RGB signals) and vertical synchronization signals (VSYNC). Or simply V signal) and horizontal sync signal (HSYNC or H signal for short). The local end unit 51 has a multiplexer 517 and a single-ended to differential converter 518. The FPGA 511 of the local end unit 51 is provided with an oscillator 513 or a signal generator. In one embodiment, the 2M test signal generated by the oscillator 513 and the RGB signal are mixed by the multiplexer 517 into R+2, G+2, B+2 signals. The 2M test signal is used to determine the phase difference between the RGB signals at the receiving end to compensate. On the other hand, the H/V signal output by the host computer is converted into a processed H/V signal (processed H/V) 5139 by the encoding or further processing of the FPGA 511, and is represented by a V, H+V signal, thus indicating H. The /V signal has been converted from a non-composite form to a composite form. The single-ended to differential converter 518 will again convert the R+2, G+2, B+2, V, H+V signals and the 8M test signal generated by the oscillator 513 into R+V+2, G+8. +2, B+(H+V)+2 and other differential image signals. The 8M test signal is used to determine the amount of attenuation of the image signal transmitted from the transmitting end to the receiving end for compensation.

The local end unit 51 has an RJ-45 interface 5301 connected to an RJ-45 interface 5302 of the remote unit 52 by a transmission line 53, thus R+V+2, G+8+2, B+(H+V)+ The 2 differential image signals are transmitted in the transmission line 53 and transmitted to the remote unit 52. The multiplexer 517 and the single-ended to differential converter 518 of the local end unit 51 can be implemented by wafers of the models QS3257 and EL5378, respectively. The local end unit also has an electronic erasable programmable read only memory (EEPROM) 516 for temporarily storing the extended display identification data (EDID) of the screen for identification by the host computer. In this embodiment, although the signal generator or oscillator 513 is provided by the FPGA 511, the signal generator or oscillator 513 may also be an element or circuit independent of the FPGA 511.

As shown in FIG. 6, remote unit 52 has a differential to single-ended converter 528 that includes an RGB converter 5282 and an HV converter 5284. The differential image signals R+V+2, G+8+2, B+(H+V)+2 from the local end unit 51 are converted into RGB signals (reduced to single-ended video signals) by the RGB converter 5282, and the differential is The image signal R+V+2, B+(H+V)+2 is transmitted through the HV converter 5284 and processed by the FPGA 521 to precipitate an H/V signal (reduced to a single-ended image signal). The RGB signal and the H/V signal are output to the screen connected to the remote unit 52 through the DB-15 interface 5400. The RGB converter 5282 and the HV converter 5284 included in the remote unit 52 in the remote unit 52 can be implemented in wafers of the type EL 9112 and ADA 485, respectively.

Referring to Figures 5 and 6, in the keyboard-image-mouse extension system of the present invention, the remote unit 52 is further connected to a keyboard or a mouse. The remote unit 52 has a PS2/USB controller 570 for processing control signals representative of the mouse or the operation of the keyboard. This PS2/USB controller 570 can be implemented on a CY7C67300 chip. The RS485 transceiver 524 of the remote unit 52 transmits a control signal representative of the mouse or the keyboard operation to the RS485 transceiver 514 of the local end unit 51, and transmits the control signal to the computer via the PS/2 or USB port. The host computer operates to connect to the computer host of the local end unit 51.

Referring to FIG. 8, in the keyboard-image-mouse extension system of the present invention, the transmission line 53 connecting the local end unit 51 and the remote unit 52 may be a fifth type of network cable having four pairs of twisted pairs therein. (twisted wire pair), in which three pairs of twisted pairs are used to transmit image-related signals, such as differential image signals R+V+2, G+8+2, B+(H+V)+2; The pair of twisted pairs are used to transmit data from a host computer or a large amount of data storage, and can also be used to transmit control signals of a mouse or a keyboard. The pair of twisted pairs are serial signals in the form of differential signals. Transmission.

The data transmission method according to the present invention comprises the following steps: (1) providing a transmission line for connecting a first module and a second module; (2) detecting a length of a transmission line; and (3) detecting the The length of the transmission line, which sets a transmission rate; and (4) when the data is transmitted within the transmission line, the data is transmitted at the transmission rate.

Referring to FIG. 9, in an embodiment, the data transmission method of the present invention comprises the following steps:

Step S402: providing a transmission line to connect a first module and a second module.

Step S404: Send a packet from the first module to detect a length of the transmission line, wherein the first module sends a first packet to the second module, and the second module returns a packet according to the first packet. The second packet is sent to the first module, and according to the time when the first module sends the first packet and the time when the second packet is received, half of the time difference is multiplied by the transmission rate at the time of the packet, thereby obtaining The length of the transmission line.

Step S406: A transmission rate upper limit is set according to the line length and transmission rate upper limit comparison table as shown in FIG.

Step S408: providing a plurality of transmission rate logic sub-units corresponding to different transmission rate upper limits, and adjusting the data transmission rate to be close to but not exceeding the transmission rate upper limit by selecting a transmission rate logic sub-unit corresponding to the upper transmission rate limit.

Step S410: The data is transmitted at a rate close to but not exceeding the upper limit of the transmission rate.

While the invention has been described above in terms of preferred embodiments, it is not intended to limit the invention. Various changes and modifications may be made without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

20. . . Computer signal transmission system

twenty one. . . First module

212, 222. . . Line length detector

214, 224. . . transceiver

215, 225, 515, 525. . . Central controller

216, 226. . . Memory

219, 229. . . Transmission rate generating unit

twenty two. . . Second module

23, 53. . . Transmission line

2190, 2290. . . switch

2191, 2291. . . First transmission rate logic subunit

2192, 2292. . . 2nd transmission rate logic subunit

2193, 2293. . . 12th transmission rate logic subunit

51. . . Local unit

510. . . First encoder/decoder

511, 521. . . FPGA

513. . . Oscillator

514, 524. . . RS485 transceiver

516. . . EEPROM

517. . . Multiplexer

518. . . Single-ended to differential converter

519, 529. . . Transmission rate logic unit

52. . . Remote unit

520. . . Second code/decoder

528. . . Differential to single-ended converter

550, 560. . . USB host controller

570. . . PS2/USB controller

5139. . . Processed H/V signal

5282. . . RGB converter

5284. . . HV converter

5301, 5302. . . RJ-45 interface

5400. . . DB-15 interface

5501, 5601. . . USB interface

2M, 8M. . . Test signal

EDID. . . Expand display identification data

R, G, B, H/V. . . Single-ended image signal

R+V+2, G+8+2, B+(H+V)+2. . . Differential image signal

DATA/KB/MS. . . Data/keyboard/mouse signal

S402, S404, S406, S408, S410. . . step

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a functional block diagram showing a computer signal transmission system implemented in accordance with the present invention.

Fig. 2 is a functional block diagram showing the transmission rate generating unit in Fig. 1.

Figure 3 shows a comparison of the line length and the upper limit of the transmission rate.

Figure 4a is a functional block diagram showing a keyboard-image-mouse extension system implemented in accordance with the present invention.

Figure 4b is a block diagram showing the function of a keyboard-image-zoom extension system (KVM extender) applied to remote control of a multi-computer according to the present invention.

Figure 5 is a functional block diagram showing the local end unit of the keyboard-image-mouse extension system of Figures 4a and 4b.

Figure 6 is a functional block diagram showing the remote unit of the keyboard-image-mouse extension system of Figures 4a and 4b.

Figure 7 is a diagram showing the keyboard-image-mouse extension system of the present invention adjusting the transmission rate according to the length of the transmission line.

Fig. 8 is a view showing a fifth type of CAT-5 network cable as a transmission line of the present invention having four pairs of twisted pairs.

Figure 9 is a flow chart showing a data transmission method implemented in accordance with the present invention.

20. . . Computer signal transmission system

twenty one. . . First module

212, 222. . . Line length detector

214, 224. . . transceiver

215, 225. . . Central controller

216, 226. . . Memory

219, 229. . . Transmission rate generating unit

twenty two. . . Second module

twenty three. . . Transmission line

Claims (34)

A computer signal transmission system includes a first module and a second module, wherein the first module and the second module are connected to each other by a transmission line, wherein the first module comprises at least: a line length detector For detecting the length of a transmission line, a central controller is coupled to the line length detector for setting a transmission rate according to the length of the transmission line detected by the line length detector; and a transmission rate The generating unit receives the transmission rate set by the central controller, and transmits the data to the second module at the transmission rate. The computer signal transmission system of claim 1, wherein the line length detector of the first module sends a first packet to the second module, and the second module transmits the first packet Returning a second packet to the line length detector, the line length detector determines the length of the transmission line according to the time when the first packet is sent and the time when the second packet is received. The computer signal transmission system of claim 1, wherein the central controller sets an upper limit of the transmission rate according to the length of the transmission line detected by the line length detector, and the transmission rate generating unit transmits the data. The rate is adjusted to be close to but not exceeding the upper limit of the transmission rate, and the data is transmitted at a rate close to but not exceeding the upper limit of the transmission rate. The computer signal transmission system of claim 3, wherein when the first module transmits data to the second module at the upper limit of the transmission rate, the second module can be restored to restore the data ( Data recovery) is correct. The computer signal transmission system of claim 3, wherein the transmission rate generating unit comprises: a plurality of transmission rate logic subunits respectively corresponding to different transmission rate upper limits; and a selection switch for selecting a pair The transfer rate logic subunit of the upper rate limit should be transmitted. The computer signal transmission system of claim 3, wherein the central controller sets the upper limit of the transmission rate according to a line length and a transmission rate upper limit table. The computer signal transmission system of claim 6, wherein the first module further comprises a memory for storing the line length and transmission rate upper limit table. The computer signal transmission system of claim 1, wherein the first module and the second module each have a signal transceiver for receiving and transmitting data. The computer signal transmission system of claim 1, wherein the first module and the second module are respectively a local end unit and a remote unit of a keyboard-image-mouse extension device, wherein the local unit The end unit is connected to a computer, and the remote unit is connected to a keyboard, a screen and a mouse. The computer signal transmission system of claim 1, wherein the first module and the second module are respectively a computer end adapter and a keyboard-image-mouse switching device. The computer signal transmission system of claim 1, wherein the transmission line is a fifth type of CAT-5 network cable. A keyboard-image-zoom extension system (KVM extender) includes at least: a first module connected to a computer host; and a second module coupled to the first module via a transmission line, the first The second module is connected to a display and a universal serial bus (USB) device, wherein the first module further comprises: a first converter for outputting a single-ended image of the host computer Converting the signal into a differential image signal; a first USB interface for connecting to one of the USB ports of the computer host; and a first encoder/decoder for transmitting the host computer to the first of the USB devices The USB signal is encoded to obtain a second USB signal; and a first transceiver is configured to transmit the second USB signal; wherein the second module further comprises: a second converter, the differential image signal Converting to the single-ended image signal and outputting to the display; a second USB interface for connecting to the USB device; a second transceiver coupled to the first transceiver for receiving the second USB signal And a second encoder/decoder The second USB signal is decoded to obtain a third USB signal, wherein the first module and the second module each have a transmission rate logic unit for adjusting the length according to the length of the transmission line. The transmission rate of the two USB signals. The keyboard-image-mouse extension system of claim 12, wherein when the first module is a transmitting end, the first module sends a packet to the second module, the second module The group generates a response signal according to the packet, and the first module obtains the length of the transmission line according to the time of sending the packet and the time when the response signal is received. The keyboard-image-mouse extension system of claim 12, wherein when the second module is a transmitting end, the second module sends a packet to the first module, the first module The group generates a response signal according to the packet, and the second module obtains the length of the transmission line according to the time when the packet is sent and the time when the response signal is received. The keyboard-image-mouse extension system of claim 12, wherein the second encoder/decoder further encodes a fourth USB signal sent by the USB device to obtain a fifth USB signal. The keyboard-image-mouse extension system of claim 15, wherein the first encoder/decoder further decodes the fifth USB signal to obtain a sixth USB signal. The keyboard-image-mouse extension system of claim 12, wherein the encoding method comprises a Manchester Encoding method. The keyboard-image-sliding extension system of claim 12, wherein the first encoder/decoder or the second encoder/decoder is a Field-programmable Gate Array (Field-programmable Gate Array; FPGA) implementation. The keyboard-image-mouse extension system of claim 12, wherein the second module is connected to a mouse or a keyboard, and the second transceiver will further represent the mouse or the keyboard operation. The control signal is transmitted to the first transceiver. The keyboard-image-mouse extension system of claim 12, wherein the first transceiver or the second transceiver comprises an RS485 transceiver. The keyboard-image-mouse extension system of claim 12, further comprising a central controller configured to set an upper limit of the transmission rate according to the length of the transmission line, wherein the transmission rate logic unit is based on the upper limit of the transmission rate Adjusting the transmission rate of the second USB signal, and adjusting the transmission rate of the second USB signal to be close to but not exceeding the upper limit of the transmission rate. The keyboard-image-sliding extension system of claim 21, wherein the transmission rate logic unit comprises: a plurality of transmission rate logic sub-units respectively corresponding to different transmission rate upper limits; and a selection switch, A transmission rate logic subunit used to select the upper limit of the transmission rate. The keyboard-image-mouse extension system according to claim 21, wherein the central controller is configured according to a line length and a transmission rate upper limit table to set the upper limit of the transmission rate. The keyboard-image-mouse extension system of claim 12, wherein the transmission line is a fifth type of CAT-5 network cable. The keyboard-image-mouse extension system of claim 12, wherein the transmission line is a twisted wire pair. A keyboard-image-zoom extension system (KVM extender) includes at least: a first module connected to a computer host and a first universal serial bus (USB) device; and a second The module is coupled to the first module via a transmission line, and the second module is connected to a display and a second USB device, wherein the first module further comprises: a first converter, One of the output signals of the host computer is converted into a differential image signal; a first USB interface is connected to the first USB device; and a first encoder/decoder is used to transmit the first USB device to The first USB signal of the second USB device is encoded to obtain a second USB signal; and a first transceiver is configured to transmit the second USB signal, wherein the second module further comprises: a second The converter converts the differential image signal into the single-ended image signal and outputs the signal to the display; a second USB interface for connecting the second USB device; and a second transceiver coupled to the first a transceiver for receiving the second USB signal; a second encoder/decoder for decoding the second USB signal to obtain a third USB signal, wherein the first module and the second module each have a transmission rate logic unit for The length of the transmission line adjusts the transmission rate of the second USB signal. A data transmission method includes: providing a transmission line for connecting a first module and a second module; detecting a length of the transmission line; setting a transmission rate according to the detected length of the transmission line; and when the data is on the transmission line When transmitting internally, data is transmitted at this transmission rate. The data transmission method of claim 27, wherein in the step of detecting the length of the transmission line, the first module sends a first packet to the second module, and the second module corresponds to A packet returns a second packet to the first module, and the length of the transmission line is determined according to the time when the first module sends the first packet and the time when the second packet is received. The data transmission method according to claim 27, wherein in the step of setting the transmission rate, an upper limit of the transmission rate is set according to the detected length of the transmission line. The data transmission method of claim 29, wherein the step of transmitting data comprises the steps of: providing a plurality of transmission rate logic subunits corresponding to different transmission rate upper limits; and selecting a transmission corresponding to an upper transmission rate limit. Rate logic subunit to adjust the rate of data transmission to near but not exceeding the upper limit of the transmission rate. The data transmission method according to claim 29, wherein the upper limit of the transmission rate is set according to a line length and a transmission rate upper limit table. The data transmission method of claim 27, wherein the first module and the second module are respectively a local end unit and a remote unit of a keyboard-image-mouse extension device. The data transmission method of claim 27, wherein the first module and the second module are respectively a computer end adapter and a keyboard-image-mouse switching device. The data transmission method of claim 27, wherein the transmission line is a fifth type of CAT-5 network cable.