Abstract:
A video signal extender includes a housing that includes only a single power supply input configured to receive electrical power, a power supply output configured to provide power to a remotely located camera, and a video signal output configured to relay the video signal from the camera to a monitor or video recording device.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention generally relates to a video signal extender. 
       BACKGROUND OF THE INVENTION 
       [0002]    Video surveillance systems are commonly used in commercial, industrial, and government settings. In many cases, multiple remotely-located video cameras send captured video back to a central base of operations. Typically, the central base of operations includes one or more recording devices on which to store the captured video. Power may be routed from the central base of operations to each of the remotely-located video cameras. 
         [0003]    When the distance between the remotely-located video cameras and the central base of operations is great, it is necessary to place a video signal extender between the camera and base of operations to prevent degradation of the video signal that would render it unwatchable. However, in conventional video surveillance systems, video signal extenders are powered from an external source, such as an electrical outlet. This often requires the installation of electrical outlets in remote locations where such installation is not normally done. This can add considerable cost and complexity to the construction and maintenance of the surveillance system. 
         [0004]    It would therefore be desirable to have a video signal extender that provides a solution to the aforementioned problem. Embodiments of the invention provide such a video signal extender. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    In one aspect, embodiments of the invention provide a video signal extender includes a housing that includes only a single power supply input configured to receive electrical power. The video signal extender also includes a power supply output configured to provide power to a remotely located camera, and a video signal output configured to relay the video signal from the camera to a monitor or video recording device. 
         [0006]    In a particular embodiment, the video signal extender includes signaling means to indicate a power connection status. In some instances, the signaling means is an LED or light bulb. In a further embodiment, the video signal extender includes signaling means to indicate a video connection status. In certain instances, the signaling means is an LED or light bulb. The video signal extender may be plugless. It may also include circuitry for re-clocking the video signal from the video camera to the monitor or video recording device. In some embodiments, re-clocking the video signal includes routing the video signal through a cable equalizer, then through a cable driver that includes a re-clocking device. 
         [0007]    In another aspect, embodiments of the invention provide a surveillance system that includes a display monitor or video recording device, and a video camera having a wired connection to the display monitor or video recording device. The surveillance system also has a video signal extender coupled between the video camera and the display monitor or video recording device. The video signal extender includes a housing that has only a single power supply input configured to receive electrical power. The video signal extender also includes a power supply output configured to provide power to a remotely located camera, and a video signal output configured to relay the video signal from the camera to a monitor or video recording device. 
         [0008]    In certain embodiments, the video camera is located more than 275 feet from the display monitor or video recording device. In a further embodiment, a second video signal extender is coupled between the video camera and the display monitor or video recording device when the video camera is located more than 550 feet from the display monitor or video recording device. The video camera and display monitor or video recording device may be HD-SDI devices. In some embodiments of the surveillance system, re-clocking the video signal comprises routing the video signal through a cable equalizer, then through a cable driver that includes a re-clocking device. 
         [0009]    Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
           [0011]      FIG. 1  is a schematic block diagram of an exemplary video surveillance system incorporating a video signal extender, in accordance with an embodiment of the invention; 
           [0012]      FIG. 2  is a front view of the video signal extender, according to an embodiment of the invention; 
           [0013]      FIG. 3  is a side view of the video signal extender, according to an embodiment of the invention; and 
           [0014]      FIG. 4  is a schematic drawing of circuitry used in the video signal extender, according to an embodiment of the invention. 
       
    
    
       [0015]    While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0016]      FIG. 1  shows a schematic block diagram of an exemplary video surveillance system  100  incorporating one or more video signal extenders  102 , in accordance with an embodiment of the invention. Each of the one or more video signal extenders  102  is positioned between a respective video camera  104  and a central base of operations  106 . The central base of operations  106  has one or more video recording devices (VRD)  108 , such as a digital video recorder (DVR), and any associated display monitors, to store and display video captured by the one or more video cameras  104 . In certain embodiments, one or more of the video camera  104 , VRD, and display monitors are high-definition serial data interface (HD-SDI) devices. The central base of operations  106  also includes an electrical power supply  110  for each of the video cameras  104 . 
         [0017]    Typically, in video surveillance systems  100  such as that of  FIG. 1 , video cameras  104  can transmit signals along a coaxial cable, for example, up to 275 feet before the signal degrades to the point where it is unwatchable. In video surveillance systems  100  in which the distance between the video camera  104  and central base of operations  106  is greater than 275 feet, the video signal extender  102  is used to restore the video signal. Multiple video signal extenders  102  may be used when the distance between the video camera  104  and central base of operations  106  is greater than 550 feet. However, depending on the particular characteristics of the video surveillance systems  100 , video signal extenders  102  may be required to restore the video signal at distances less than or greater than 275 feet. 
         [0018]    Unlike conventional video signal extenders, the video signal extender  102  of the present invention does not plug into an electrical outlet. Instead, the video signal extender  102  is powered by the same power supply  110  used to power the video cameras  104 .  FIGS. 2 and 3  illustrate front and side views, respectively, of a particular embodiment of the video signal extender  102 . In the embodiment shown, the video signal extender  102  is plugless. Thus, the video signal extender  102  obtains all of the power needed for its own operation from power supply  110 . 
         [0019]    The video signal extender  102  includes a housing  114  with first and second ports  116 ,  118  having BNC connectors. First port  116  is a video input which receives the video signal transmitted by the video camera  104 . Second port  118  is a video output which transmits the video signal to the base of operations  106  and its video recording devices  108  and associated displays. In alternate embodiments, first and second ports  116 ,  118  may include connectors other than BNC connectors. 
         [0020]    In the embodiment shown, third and fourth ports  120 ,  122  include wire connectors. In certain embodiments, the wire connectors are push-in or quick-connect-type connectors which allow for a bare end of the wire to be inserted into the third and fourth port wire connectors. Third port  120  is for the power input from electrical power supply  110 , while fourth port  122  is the power output to the video camera  104 . In certain embodiments of the invention, the power input and output is 12 volts DC. In other embodiments, the power input and output are 24 volts AC. However, it is envisioned that the power input and output voltage levels could be greater or lesser than the levels cited above. It is further envisioned that these power input and output voltages can be either AC or DC. 
         [0021]    The side view of  FIG. 3  shows first and second visual signaling means, or LEDs  124 ,  126 . First LED  124 , when lit, indicates a good video connection. Second LED  126 , when lit, indicates a good power connection. In some embodiments, the first and second LEDs  124 ,  124  are color-coded to be easily distinguishable. In alternate embodiments, visual signaling means other than LEDs may be used. A small light bulb or other suitable light-emitting device may be used. 
         [0022]      FIG. 4  shows a schematic diagram for an exemplary circuit design  150  for use in the video signal extender  102 , according to an embodiment of the invention. In the embodiment shown, the circuit design  150  does not amplify the video signal from the video camera  104 , but instead equalizes and re-clocks the video signal. 
         [0023]    As the length of the video cable increases, so does the attenuation of the video signal being transmitted along the cable. The attenuation is proportional to the square root of the signal frequency. An active equalizer operates to automatically adjust the gain of the equalization so that the output of the equalizer is the same as the original signal. To efficiently recover the video signal, the equalizer may be designed to dynamically adjust its gain. Thus, a cable equalizer may be configured such that the attenuation of the video signal is determined, and further configured such that the gain adjustment is controlled via a feedback loop. This allows the cable equalizer to automatically adjust its gain so that a signal transmitted along various lengths of the video cable can be equalized. 
         [0024]    However, even with equalization of the video signal, there can still be some signal degradation due to jitter. Jitter is the deviation of a signal&#39;s transitions in time from their ideal positions. Re-clocking a video signal can be thought of as “refreshing” or “regenerating” the signal. When a video signal is transmitted over a relatively long length of cable, the signal can suffer significant degradation. This signal degradation can take the form of noise and interference, decrease in amplitude, and most significantly “rounded edges” as the signal transitions from low-to-high or high-to-low (essentially low-pass filtering of the signal due to the capacitance of the cable). If this degradation becomes too severe, the video signal can be rendered unusable or unwatchable. To prevent this, a re-clocking device can be inserted in the signal chain. Typically, the re-clocking device uses the incoming signal as a template to regenerate a new signal with the same characteristics. Stated another way, re-clocking relies on the fact that the receiver knows the data-rate of the initial signal. The re-clocking device generates a stable, local clock at the known frequency, and re-clocks the signal coming out of the equalizer in order to reduce the accumulated jitter. 
         [0025]    Referring again to  FIG. 4 , circuit design  150  includes power input  152  and video input  154 . As can be seen from  FIG. 4 , the video signal from video camera  104  (shown in  FIG. 1 ) is input at video input  154 . The video signal is equalized by cable equalizer  156 , which takes the video signal and sends the equalized output to cable driver  158 . In the embodiment of  FIG. 4 , the cable drive  158  includes a re-clocking device. Cable driver  158  sends the re-clocked video signal to first video output  160 . A second video output  162  is also provided. 
         [0026]    All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
         [0027]    The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
         [0028]    Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.