TWI246009B - Automatic equalization of video signals - Google Patents

Abstract

A video compensation system for analog video transmission is described. The compensation system is employed in an analog video switching circuit such that each time a conductive path is switched, the system automatically tests the new switch path for a new compensation value. The compensation value is determined by measuring the response of the new path to a set of tones that are applied to the conductive path, the response to which is measured against a table of responses previously recorded. The measured responses are compared to the recorded responses to determine an appropriate compensation control voltage, which is applied to an equalizer system. In an alternative embodiment, the skew compensations also provided between red, green, and blue twisted pair lines in the cables by performing comparative analysis between corresponding pairs of the red, green, and blue signals.

Description

1246009 Description of the invention The example in Figure 1 is just an exemplary embodiment of how the AMS system is configured into a distribution structure. By reviewing the oldest, those skilled in the art will understand many structures (simple or more complex configurations). Furthermore, the example of FIG. 1 is merely described to give a surrounding environment in which the present invention is applicable, and the example is by no means intended to limit the broad perspective of the present invention. The system in Figure 1 provides a server! The KVM signal is controlled and switched between 15 and Workstation 3, and as a whole, it is also controlled by the system's MSA application 29. The AMS system in Figure 1 operates independently of software programs on the server 10 or workstation. Basically, the system establishes the connection I between the user on the 36-40 and the server 10-15, the switching and sending of KVM signals in the entire system, user authorization, and MSA 29 Guided software upgrades at the system level at the end of the unit. 15 As background, AMS 22-24 is connected to server 10-15 through CIPs 16-21. CIPs convert local KVM connections into proprietary long-distance signals and serve as an interface between a separate server and the KVM matrix system. The connection between the ciP and the AMS unit can be done with an industry standard uTPlus cable, just like all other connections between system components. 20 On the workstation side, the user is connected to Ba through 11-11531-35] \ 48 22-24. AUPs are a desktop design with power supply and can provide peripheral support for many different workstation types, such as PS / 2, Sun, etc. As shown in Figure 1, the AUP can be connected directly to a pair of four AMS or CIP modules via a UTPlus cable. AUPs may be in a mixing and matching group 1246009, invention description, such as AUP 34, which communicates with AMS 25 and CIP 21. Because the structure of the system using the present invention is not critical to the present invention, the example in FIG. 1 is only for explaining the analog video signal transmission between the component servers, CIPs, AMSs, AUPs and workstations. 5 In the example in Figure 1, AMS 22-25 is connected to server 10-15 through CIP 16-21 to convert the KVM signal from the local connector and sent to the long-line (long-distance) protocol. The physical connection between CIPs and AMSs is wound through UTPlus. On the other hand, AMSsm is also connected to AUPs 3 1 · 3 5 by uTpius cable. The maximum distance between CIPs and AUPs is dominated by degradation that occurs in analog video signals over long distances. For high-bandwidth, high-quality video with current compensation mechanisms, it is difficult to obtain a distance between CIPs and AUPs of about 300 meters. The basic purpose of AMS is to switch the video (and data) between input and output, thereby connecting the selected workstation 36-40 to the selected computer ι〇_15. 15 [Summary of the Invention 3 Summary of the Invention The analog user cabin (AUP) is the main user terminal interface of the AMS system. 8: 17-31-35 provides a KVM connection between the user terminal and Dove ~ 22_25 or CIPs 16-21. Because video degradation occurs in the electrical delay 20 d ', the present invention relates to a method for correcting video distortion caused by signal loss during video transmission. In one example, such revisions were born in AUP 31_35 and were performed during each switch from a user to a server. AUP also provides on-screen menu-based technology to allow users to select a new computer through the on-screen menu 1246009 玖, invention description for connection. Each time the user uses the OSD menu to select a new computer, the video correction function can be performed by the AUP to allow the user to be provided with fully compensated video shortly after the initial switch request. On the other hand, the computer interface module (CIP) converts the computer KVM signal into 5-a type that can be downloaded to AMS or AUP along the UTPlus cable. All UTPlus cables described here are usually four pairs of unshielded, twisted pair cables, which are graded category five or better. Of course, other alternative cables can be used in systems that also use the compensation system of the present invention. Each CIP uses a KVM computer port and a local connector for servers 10-15. 10 Matrix Switch Manager (MSA) 29 is a client software on computer 30 that allows the administrator of the analog matrix system to be easily configured from an additional LAN 28 or a remote computer 30 connected via a crossover cable , Monitor and maintain the system. MSA 29 allows administrators to perform functions such as user settings, server settings, system monitoring, system management, system login, and so on. MS A 15 29 can also perform port status, event registration, tracking routing, etc. via its network port. As mentioned earlier, in the system of Figure 1, and other analog matrix switching systems, the analog video is degraded as it travels along the cable. The invention compensates for video distortion on industry standard cable transmissions (such as CAT5, CAT5e and CAT-6 (20 including gigaflex), and any other standard electron microscope transmission) to provide high-quality video, up to 10-15 10,000 feet away. Compensation is accomplished by three compensation features, which are used independently or in any combination. The first is to automatically adapt to cable equalization, where the system automatically corrects frequency-dependent attenuation each time a correct KVM path is selected.

Claims (1)

I24_93 Patent application scope 1 · An analog video switch, which includes: a switch 'to establish different conduction paths between a group of workstations receiving analog video signals and a group of servers transmitting analog video signals; 5- A memory device 'stores a predetermined table of response characteristics of a specific conductor path pattern when the conductor path pattern receives a set of predetermined frequency tones; a test circuit that communicates with different conduction paths to record the conduction path The measured response to the set of pre-determined frequency tones; 10 an equalizer circuit to apply a compensation signal to the analog video signal component in relation to the conduction path to the set of pre-determined frequency tones. 2. The switch according to item 1 of the scope of patent application, wherein a set of hue having a predetermined frequency is selected between a value of 325 κΗζ and a value of 48 MHz. 15 3. The switch of claim 1 in the patent scope further includes a multi-turn test circuit and an equalizer, one for each component of the analog video signal. 4. The switch according to the scope of the patent application, wherein the test circuit includes at least one computer interface module and at least one user module. 5. The switch of the fourth item in the scope of patent application, in which the computer interface cabin includes a circuit for receiving a tone request from the user cabin and responding to the conduction path by applying the group of predetermined tone frequencies. 6. The switch of item 5 in the scope of Patent No. 4, in which the user cabin issues a hue request and judges the measured response. 7. As stated in the patent range switch, the equalizer includes a set of low 27 _9i; ν ^ ~ fe, 'patent application range', and high filter, which are independently controlled by the compensation signal . 8 · An analog video de-shifting circuit for video compensation of color video transmitted on cables with different transmission delays, including: 5 one switch to receive three individual color video components on three inputs One, and select two of the three color video components as a rotation, then the other two of the color video components, and then at least one correspondence of any one of the two color video components; a right-angle circuit, to Rectangle the edges of each of the two color video component pairs approximately; a phase detector 'to detect the phase difference between the rectangular video components; a integrator coupled to the phase detector; A digitizer to digitize the output of the integrator; 15 a processor to generate a control signal in response to the output of the integrator; and a delay circuit to add a selective delay to the three color video components based on the control signal . For example, it is stated that the circuit of item 8 in the patent claims that one or more right-angle 20-phase detectors, integrators, digitizers, and processors are included in a common integrated circuit. 10. The circuit of claim 8 in which the delay circuit includes an additional switch that controls a plurality of binary delay values. U · An analog video signal that compensates for transmission over an undefined cable length 28 The method of claiming the patent scope includes: when the conductor path pattern of the path length receives a set of color tones with a predetermined frequency, storing in advance the response characteristics of a specific conductor path pattern of one of the many incremental conductor path lengths Decision table; each set of pre-determined compensation values for each of the response characteristics is stored for each of the conductor path lengths; the undecided electrical viewing length of the conductor path type is tested to record the cable length for Set of pre-determined frequency hue measurement responses; 10 15 Compare the measured response with the pre-stored table to identify a close match between the measured response value and the pre-stored table value; identify a counterpart of the pre-determined compensation value; compare the pre-stored value The corresponding value of the determined compensation value is applied to a first equalizer to compensate the analog video component. η The method as described in the patent application, where the county determines the frequency of the color is selected between 325KΗζ and 48MHz. 13. The method in the scope of the Chinese Patent Application, which further includes receiving-tone requirements and responding by applying the set of predetermined frequency tones to the cable length. 20 14 · If the compensation value of item No. 丨 丨 of the scope of patent application is applied to this method 15 · If the compensation value of item No. 14 of the scope of patent application is applied to the method, it further includes the corresponding device as low, medium And high compensation values. The method further includes using the counterpart as a dc pass value. 29 Γ './' lose 3 faces t Τ t t 铖 2 Han