Patent Publication Number: US-8112784-B1

Title: Device comprising multiple channel selectors

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application Ser. No. 60/566,300, titled DEVICE COMPRISING MULTIPLE CHANNEL SELECTORS filed Apr. 28, 2004, which application is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to television converter devices for providing television programming to subscribers. More particularly, the invention relates to a television converter device for providing television programming to multiple TVs at a subscriber location. 
     BACKGROUND OF THE INVENTION 
     Most modern entertainment systems now include a television converter device, often in the form of a set-top-box (STB), as well as a television (TV). While TVs typically include tuners capable of selecting a channel of television programming from the multitudes of channels broadcasted over the air (typically via an attached TV antenna), STBs have become standard to access and select channels of television programming provided by alternate distribution services such as cable and direct-to-home satellite services. 
     STBs typically contain some kind of a channel selector, a control means, and typically a separate remote controller, for the user to give instructions to the STB. Channel selectors could take any form, ranging from a simple radio tuner to complex and specially designed hardware and software devices. In simple terms, channel selectors can select any channel of television programming from the multiple channels delivered to the STB by the programming distributor and then deliver that channel of television programming to the TV in a form that the TV is able to recognize and subsequently display (typically via channel 3 or 4 on the TV&#39;s tuner or via a separate baseband input). Current industry practice is for a programming distributor to provide each subscriber with one STB (with one channel selector) for each of the subscriber&#39;s TVs. 
     Modern STBs now support a wide array of functions and services that go beyond simple channel selection. It is now common for STBs to also be digital video recorders (DVRs) through the internal or external inclusion of a hard drive or other storage device, along with the associated control hardware and software. Many STBs also allow users to directly order pay-per-view movies from the programming distributor via a modem connected to a telephone line at the subscriber&#39;s location. Increasingly, STBs store information related to certain user preferences that increase user friendliness of the service. It has also become important that STBs provide users with some means of blocking undesirable television programming. 
     The trend in STB design is to include more and more components and functionalities in the STB. There is an economic incentive for this trend, as including an additional component in the STB is cheaper than providing that component as a standalone device. In addition, there is an operational incentive as the STB manufacturer can ensure that an included component will operate correctly with the other included components, thus increasing customer satisfaction with the overall product. Lastly, many consumers find entertainment systems with a large number of standalone components difficult to use. 
     As the trend has continued, several problems with the typical STB have been identified. One problem with STBs is associated with the recent development of the picture within a picture functionality found on some TVs, sometimes also referred to as picture-on-picture or picture-in-picture (PIP) display. PIP display allows a user to watch to two channels at the same time: typically with one channel shown in a substantially smaller window that overlays the other displayed channel that is shown on the main TV screen. This functionality, however, requires the use of an extra tuner or channel selector for each additional channel to be displayed. The additional channel selectors proportionally increases the cost of the device, be it a TV or STB, even though the second channel selector remains idle most of the time. 
     Yet another drawback to typical STBs is the inability to perform housekeeping functions, such as downloading system information, software updates, menus, and any content to be stored and displayed later or uploading stored information such as user viewing information and system performance information, while the STB is in use. As STBs have become more complicated, the need for performing such housekeeping functions has drastically increased. Most housekeeping functions, especially those that require the downloading of information embedded in a channel, require the use of a channel selector. However, because modern STBs typically contain a single channel selector, housekeeping functions requiring a channel selector cannot be performed while the channel selector is in use delivering television programming. 
     Programming distributors currently get around this problem in one or both of two ways. One way is to insert such housekeeping information in every channel of content delivered. Therefore, regardless of whether the channel selector is in use or not, housekeeping information is always available. This is a simple solution but is clearly an inefficient use of bandwidth. Another way is to wait until the STB is turned off to perform housekeeping functions. This, however, means performance of the housekeeping functions must then be dependent upon the user&#39;s use habits, which could prevent the functions from being performed in a timely manner. In addition, many users leave their STBs on all the time thereby preventing the performance of such housekeeping functions. 
     Another problem with modern STBs is referred to as ‘tuner delay.’ It takes all tuners and channel selectors a finite amount of time to “tune” from one channel to another. For example, a satellite STB can take up to two seconds to display a new channel after the receipt of a channel change command, during which time nothing is being delivered to the TV. This tuner delay is perceived by the subscriber and can be the source of much frustration on the subscriber&#39;s part. Better quality electronics can be used to reduce tuner delay, but the delay cannot be eliminated. In addition, such better quality electronics are also subject to the law of diminishing returns and they can typically cost much more than a lower quality tuner, for only an incremental decrease in tuner delay. 
     Programming distributors have also determined that it is now a problem that STBs can only support one TV. Although the additional functions have proved to be very popular with consumers, they have drastically increased the cost and complexity of STBs. For example, the cost of including an internal storage device can substantially increase the manufacturing cost of STBs. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention are methods and apparatuses that solve these and other problems associated with modern STBs. Embodiments of the present invention comprise a device, such as an STB, that includes two or more channel selectors and the necessary control electronics to allow each of the multiple channel selectors to operate independently. STB embodiments of the present invention may be connected to and support one or more TVs up to as many TVs as there are channel selectors in the STB. The STB embodiments allow each connected TV to receive television programming independent of what any other connected TVs may be receiving, at a significant cost savings over providing separate STBs for each TV. 
     For embodiments of the present invention wherein the device, such as an STB, includes additional components and functionalities, such as storage devices that support a DVR functionality, the control electronics also allow the channel selectors to share the additional components and functionalities, thus allowing any connected TV to also share them. For example, one STB embodiment that includes DVR functionality allow each attached TV to independently access any television programming stored on the STB&#39;s storage device and can store television programming independently of what is being displayed on any attached TVs. Another STB embodiment in accordance with the present invention may retrieve stored television programming from the storage device and deliver it to a first TV while, substantially simultaneously, retrieve and deliver other stored television programming to a second TV and store yet other television programming on the storage device. 
     The use of multiple channel selectors in a STB also allows the STB to provide PIP functionality. In one embodiment of an STB with two channel selectors, the STB can be operated in and switch between two modes: a PIP mode wherein both channel selectors deliver television programming to a single TV (i.e. one as a PIP display); and a two TV mode wherein each channel selector independently delivers programming to separate TVs. In another embodiment, one channel selector can deliver the same programming to two or more TVs simultaneously, for example as a PIP display on one of the TVs. In another embodiment of an STB with three channel selectors, the STB can be operated in multiple modes including: a PIP mode wherein all channel selectors deliver television programming to a single TV (i.e. two as PIP displays); a two TV mode wherein at least one of the TVs also has PIP functionality; and a three TV mode wherein each channel selector independently delivers television programming to three separate TVs. Thus, the present invention can support PIP functionality on multiple TVs at a significant cost savings to the user over the need for separate PIP-functional STBs for each TV. 
     The use of multiple channel selectors in a STB also allows the STB to perform housekeeping functions when any one of the channel selectors are not in use. Embodiments also include having an additional channel selector dedicated to performing housekeeping functions. The embodiments greatly increase the reliability and timeliness of the performance of housekeeping functions. 
     The use of multiple channel selectors can also reduce tuner delay. Thus, a channel change, in many instances, may be achieved by switching between channel selectors when appropriate. Idle channel selectors can be tuned to frequently selected user channels or a user&#39;s favorite channel. In addition, in an embodiment one very high quality (and thus high cost) channel selector with a very low tuner delay is provided along with a number of lower quality, less expensive channel selectors. Once a command is received to change channels, initially the fast channel selector tunes to the new channel. At some later time, the fast channel selector ‘hands off’ delivery of the channel to one of the slower channel selectors, leaving the fast channel selector available for the next channel change. This embodiment allows the present invention to reduce tuner delay to all attached TVs while requiring only one high quality channel selector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  illustrates a entertainment system utilizing a STB in accordance with an embodiment of the present invention. 
         FIG. 1   b  is a functional block diagram of the logical elements of an STB comprising an embodiment of the present invention. 
         FIG. 2  illustrates a functional block diagram of one embodiment of an STB with two channel selectors in accordance with the present invention. 
         FIG. 3  illustrates a functional block diagram of one embodiment of an STB with three channel selectors in accordance with the present invention. 
         FIG. 4  illustrates a functional block diagram of one embodiment of an STB with two channel selectors and an internal storage device in accordance with the present invention. 
         FIG. 5  illustrates a functional block diagram of another embodiment of an STB with three channel selectors in accordance with the present invention. 
         FIG. 6  illustrates the logical steps of one embodiment of a method of operating a STB with multiple channels selectors and an internal storage device. 
         FIG. 7  presents the logical steps of a more detailed method of operating a STB with multiple channels selectors and an internal storage device. 
         FIG. 8  presents the logical steps of a method of performing housekeeping operations on a STB with multiple channels selectors and an internal storage device. 
         FIG. 9  presents the logical steps of an embodiment of a method of operating a STB with an internal storage device and multiple channels selectors, wherein one of the channel selectors has a substantially shorter tuner delay. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In this specification, the present invention will be described using methods and systems related to subscriber satellite television service. This specific description is not meant to limit the invention to that one embodiment. The present invention may also be applicable to cable television systems, broadcast television systems or other television systems. The present invention is also described in terms of digital video recorder (DVR) devices. The present invention may also be applicable to digital-versatile-disc (DVD) recording devices or other television recording devices. One skilled in the art will recognize that the present invention can apply elsewhere. While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various other changes in the form and details may be made therein without departing from the spirit and scope of the invention. 
     As a general matter, the disclosure uses the term “signal.” One skilled in the art will recognize that the signal may be any digital or analog signal. Those signals may include, but are not limited to, a bit, a specified set of bits, an A/C signal, or a D/C signal. Uses of the term “signal” in the description may include any of these different interpretations. It will also be understood to one skilled in the art that the term “connected” is not limited to a physical connection but can refer to any means of communicatively or operatively coupling two devices. 
     As another general matter, the disclosure uses the terms “television converter,” “receiver,” “STB,” “television receiving device,” “television receiver,” “television recording device,” “satellite STB,” “satellite receiver,” “cable STB,” “cable receiver,” and “television tuner” to refer interchangeably to a converter device or electronic equipment that has the capacity to acquire, process and distribute one or more television signals transmitted by broadcast, cable, telephone or satellite distributors. DVR and “personal video recorder (PVR)” refer interchangeably to devices that can record and play back television signals and that may implement trick functions including, but not limited to, fast-forward, rewind and pause. As set forth in this specification and the figures pertaining thereto, DVR and PVR functionality or devices may be combined with a television converter. The signals transmitted by these broadcast, cable, telephone or satellite distributors may include, individually or in any combination, internet, radio, television or telephonic data or information. One skilled in the art will recognize that a television converter device may be implemented as an external self-enclosed unit, a plurality of external self-enclosed units or as an internal unit housed within a television. One skilled in the art will recognize that the present invention can apply to analog and digital satellite STBs. 
     As yet another general matter, it will be understood by one skilled in the art that the term “television” refers to a television set or video display that may contain an integrated television converter device (e.g., an internal cable-ready television tuner housed inside a television) or, alternatively, that is connected to an external television converter device (e.g., an external STB connected via cabling to a television). A further example of an external television converter device is the EchoStar Dish PVR 721, Part Number 106525, combination satellite STB and DVR. 
     Finally, as a general matter, it should be understood that satellite television signals may be very different from broadcast television or other types of signals. Satellite signals may include multiplexed, packetized, and modulated digital signals. Once multiplexed, packetized and modulated, one analog satellite transmission may carry digital data representing several television stations or service providers. Some examples of service providers include HBO™, CSPAN™, ABC™, CBS™, or ESPN™. In satellite television, a service provider can also be compared to a “channel.” 
     The term “channel,” as used in this description, carries a different meaning from its normal connotation. In broadcast television, different analog signals of a television station may be carried on a carrier frequency and its sub-channels. A tuner in a television may then acquire and process these signals. In broadcast television, the term channel has thus become synonymous with the sub-channel or the station on that sub-channel. The normal connotation of the term “channel” is therefore not always appropriate to describe satellite television transmissions where multiple stations may be multiplexed onto a single carrier frequency. Satellite television distributors, however, may organize the satellite data into a group of different “virtual channels.” These virtual channels give the impression that the satellite television programs (the service providers) are placed in channels. This impression may assist user operation of the satellite STB since it models an analog television or analog receiving device. The virtual channels may appear in the electronic program guide (EPG) data and the user may choose programming by selecting a virtual channel. For instance, the user can select HBO, which may be on virtual channel 300, or CSPAN, which may be on virtual channel 210. These service providers or virtual channels are not necessarily carried in the same signal being sent from the same satellite. EPG data may come from a service provider (e.g., HBO), content provider (e.g., Disney), a third party (e.g., TV Guide) or from another outside entity. Thus, in satellite television service a channel may not be the same as in broadcast television service. Rather, channels may be more properly termed service providers in satellite television service. The term “channel” will be used in this description to describe the service providers and the virtual channels they may occupy. 
     Turning now to the Drawings, wherein like numbers denote like parts throughout the several views,  FIG. 1   a  presents an embodiment of an entertainment system  102  that includes a television converter device  100  in the form of a satellite STB (STB). Generally, the satellite STB  100  may receive one or more television signals from a cable television distributor, from a broadcast television distributor or from a satellite television distributor  104 . As a preferred embodiment, entertainment system  102  receives signals from satellite television distributor  104 . One skilled in the art will recognize that STB  100  may also receive video-digital subscriber line (DSL), Internet, wireless and other signals from content or video distributors. The satellite STB  100  may process television signals and may send the processed signals to one or more peripheral electronic devices, such as televisions  120 ,  132  and remote controls  126 ,  134 . The satellite STB  100  also may accept commands from remote controls  126 ,  134  or other peripheral electronic devices. More detail about the functionality of the satellite STB  100  is provided below. One skilled in the art will recognize that many embodiments of the entertainment system  102  are possible and within the scope of this invention. Other such embodiments may include, but are not limited to, various combinations or permutations of devices and connections for the delivery, storage, and display of communications, content and other data. 
     To further describe the entertainment system  102 , embodiments relating to receiving satellite television signals will be explained in more detail. A satellite television distributor  104  may transmit one or more satellite television signals  128  to one or more satellites  106 . Satellite television distributors may utilize several satellites  106  to relay the satellite television signals to a subscriber. Each satellite  106  may have several transponders. Transponders transmit the signal  130  from the satellite to the subscriber. For example, these signals  130  may be transmitted at a frequency of 2150 Mhz. 
     A transponder may also polarize the transmitted signal  130  in several ways. One form of polarization in satellite transmissions is circular polarization. For example, transponders of satellite  106  may transmit two signals (together as signal  130 ) on the same transponder, one signal that is right-hand polarized and another signal that is left-hand polarized. In other words, two signals may be simultaneously transmitted with opposite polarizations. The opposite polarizations may prevent interference. One skilled in the art will recognize that other ways of polarizing signals are possible. 
     The polarized signals can be received at satellite communication device  108 . The satellite communication device  108  may include one or more of the components that follow. One component of satellite communication device  108  may be a satellite dish. A satellite dish can focus the signal on one or more low-noise block filters (LNBF), also referred to as low-noise block down converters (LNBDC). The LNBFs may de-polarize and initially process the signal. This initial processing may include filtering noise from the signal and down-converting the signal. Down-conversion is sometimes required to transmit the signal  110  through certain cables, such as coaxial cables. The signal  110  arrives at the television converter device  100  via cabling. One skilled in the art will recognize that other methods and other systems of delivering the satellite signal  110  to the satellite STB  100  may be possible. 
       FIG. 1   b  illustrates a high-level block diagram showing some of the logical elements of a STB  100  in accordance with one embodiment of the present invention.  FIG. 1   b  illustrates an embodiment of the STB  100  that contains two channel selectors  150 ,  152 . It will be understood by the reader that the methods and apparatuses described herein will be equally applicable to embodiments that contain any number of channel selectors greater than one channel selector. 
     In the embodiment shown in  FIG. 1   b , the STB  100  also contains an internal storage device  154 . The storage device  154  is capable of recording and storing television programming provided by any of the channel selectors  150 ,  152 . The storage device  154  is further adapted to retrieve stored television programming and deliver it to any TV  120 ,  132  connected to the STB  100 . In embodiments, the STB  100  may also include at least one temporary buffer  156 . This buffer may comprise RAM or may simply be a portion of the storage device  154 . The buffer  156  may be used to manage the flow of television programming to the storage device  154  and, in some embodiments, to the connected TVs  120 ,  132 . 
     The STB  100  also contains control electronics  158  that control the operation of the channel selectors  152 ,  150  and the other logical elements contained in the STB  100 . The control electronics  158  may be one or more of a multitude of commercially available processors such as the Motorola™ 68000 or a processor from the Intel™ Pentium™ family. In addition, the control electronics  158  may be any type of custom ASIC, such as from the LSILogic G11 family, or FPGA, such as from the Altera Stratix™ family. In addition, the control electronics  158  may include discrete electronic components combined into a single circuit. The control electronics  158  may operate under the control of a software program, firmware program, or other program stored in memory or control logic. One skilled in the art will recognize that other embodiments of the control electronics  158  are possible. In the embodiment shown in  FIG. 1   b , the control electronics also include a modem for interfacing with the telephone line  112 . 
     The STB  100  contains a remote controller interface (RCI)  160 . The RCI  160  is capable of receiving commands from the STB&#39;s remote controllers  126 ,  134  and relaying them to the control electronics. In some embodiments, the RCI  160  may also send commands to the various remote controllers. In embodiments, at least one remote controller specific to each display device supported by the STB  100  is required. The STB  100  is able to identify the individual remote controllers and deliver programming to their associated TV. In one embodiment, each remote controller when sending a command to the STB  100 , also sends a unique identifier that indicates which TV the command relates to. This is but one example; other means of associating specific remote controllers with specific TVs are well known in the art and applicable here. As noted before, it is typical for remote controllers to include IR or UHF transmitters for wireless communication with the STB  100 . Because it is assumed that in any particular instance no more than one TV will be collocated with the STB  100 , UHF transmitters are used in remote controllers of TVs not collocated with the STB  100 . This is because UHF signals can easily penetrate walls of a typical home and communicate with a distant STB  100 , whereas IR signals cannot. For embodiments wherein the STB  100  is designed to be located in the basement or some other central location, all remote controllers use a UHF transmitter. It should be noted that UHF transmitters are but one example of a means for relaying information to a STB  100  located in a different room at a subscriber location. Other examples include wireless local area network (LAN) protocols such as Bluetooth, all of which are applicable here. 
     As  FIG. 1   b  shows, each channel selector  150 ,  152  in the STB  100  is shown as an independent element. The channel selectors can tune to or ‘select’ specific channels within the incoming signal  110  and deliver it to the internal storage device  154 , the temporary buffer  156  or any connected TV  120 ,  132  or display device as directed by the control electronics  158 . The channel selectors  150 ,  152  are each a device or set of devices that processes the signal  110  provided by the satellite communication device  108 . In other words, each channel selector  150 ,  152  may include demodulators, decoders, demultiplexers, and data packet selectors. One skilled in the art would recognize that the channel selectors  150 ,  152  may include fewer, more, or different components. The term channel selector  150 ,  152  is used herein to avoid confusion and remind the reader that the invention applies equally to analog and digital television receiver  100 . 
     Of interest here is the independence and interchangeability of the channel selectors  150 ,  152  as they are used by the STB  100 . Thus, in the two channel selector embodiment shown in  FIG. 1   b , at any given time any of the channel selectors may be idle, delivering television programming to one or more connected TVs  120 ,  132 , delivering programming as a PIP display to one or more connected TVs  120 ,  132 , delivering television programming to the internal storage device, delivering programming to the temporary buffer, or performing housekeeping functions. The only limiting factor is that each channel selector  150 ,  152  may only select and deliver programming from one channel at a time.  FIGS. 2 through 5  describe specific embodiments and give specific examples further illustrating the independence and interchangeability of the multiple channel selectors. 
     In the embodiments shown in  FIG. 1   a  and  FIG. 1   b , the STB  100  in accordance with the present invention is implemented as a stand-alone device. One skilled in the art will recognize that the present invention may be implemented in any number of ways and need not be a stand-alone device proximate to a TV. For example, the STB  100  may be a stand-alone designed to be located in a basement or some other central point at the subscriber&#39;s location that allows convenient connection to various devices in other rooms at the location. As another example, embodiments of the present invention may be implemented as part of a central home theater device that includes a display device and stereo sound system. A further example would be a home digital video storage library device, such as a DVD player with large capacity storage device, or a portal device to a remote video library. Such a library device would utilize the present invention to allow all the TVs at the subscriber&#39;s location to independently access television programming stored on or transmitted through the library device. 
     Furthermore, one skilled in the art will recognize that there are many different electronic means for implementing the present invention, regardless of the component, device or location of the STB. Such means include software means comprising software that can be executed at need on a processor within a component comprising the necessary hardware elements, firmware means wherein a fixed set of commands to be executed by a processor is embedded with the control circuitry of a component, hardware means wherein the present invention is expressed as fixed circuits that perform the functions when operated, or some combination of software, firmware and hardware means. From this discussion it should be clear that the present invention is directed more towards the functions and methods performed by the STB  100  than towards any specific means or devices for executing those functions. 
       FIGS. 2 through 5  show functional block diagrams of various STB embodiments of the present invention to illustrate the functionality of the present invention. Not shown in the FIGS. are those common elements of the STB that are not central to the illustration of the functionality of the present invention including, for example, the control electronics, the RCI, power supply, and cooling fan. 
       FIG. 2  shows a functional block diagram of one simple embodiment  200  of an STB  202  in accordance with the present invention capable of independently delivering television programming to two connected TVs (TV  1   210 , and TV  2   212 ) and in addition provide PIP functionality to TV  1   210 . The STB  202  receives a signal  211 , such as the filtered signal  110 , containing multiple channels of television programming from a programming distributor. The STB  202  is equipped with two channel selectors (channel selector  1   204 , and channel selector  2   206 ). The channel selectors  204 ,  206  each are able to select one channel of television programming from those that are contained in the signal  211  and deliver the selected channel of television programming to a connected TV or other device. 
     One skilled in the art will realize that the exact design of a channel selector can vary depending on the nature of the signal  211  of multiple channels (i.e. whether the television programming is in a digital or analog form, etc.). For example, a channel selector may include a digital decoder to change digital television programming (e.g. an MPEG-2 video signal as used by some direct-to-home satellite programming distributors) to an analog television programming signal (referred to as a baseband signal). Channel selectors for use digital television programming will also have some amount of on board buffering capacity, usually in the form of one or more RAM chips. In addition, the above channel selector may further include an NTSC encoder. NTSC encoders are used to modulate a baseband signal onto a channel 3 or channel 4 carrier frequency that subsequently can be displayed by TVs tuned to those channels. Channel selectors, digital decoders and NTSC encoders are well known in the art and need not be described further herein. 
     In the embodiment shown in  FIG. 2 , channel selector  1   204  is directly connected to TV  1   210  and is dedicated to delivering television programming to TV  1 . Channel selector  2 , however, can be connected to either TV via a switch  220 . This switch  220  illustrates the STB&#39;s ability to switch between 2 modes: a PIP mode and a two TV mode. While in 2 TV mode, channel selector  2  is connected through the switch  220  to TV  2   212 . Thus, while in this mode the STB  202  independently supports both TVs and each user is capable of viewing any channel available without interfering with the delivery of television programming to the other TV. For example, a user viewing one TV can view or select any channel the user desires regardless of, and without interfering with, what the user of the second TV is viewing. 
     While in PIP mode, channel selector  2   206  is connected through the switch  220  to TV  1   210 . In this configuration, channel selector  2   206  is capable of delivering television programming as a PIP display on TV  1   210  within that television programming that is delivered by channel selector  1   204 . 
     While a simple switch  220  is used to illustrate the ability of the STB  202  to switch the channel selectors between modes, one skilled in the art will realize that the switch  220  is merely illustrative and that some additional standard electronics, including PIP display circuitry, would be necessary to effectuate the functionality. However, such PIP display circuitry and other video signal combination and switching circuitry is well known in the art and need not be shown or discussed here in detail to adequately describe the present invention. 
     Another embodiment (not shown) of the present invention is a simple variation of the embodiment shown in  FIG. 2 . In the embodiment, channel selector  1   204  is also provided with a switch thus allowing PIP functionality to be available to both TV  1   210  and TV  2   212 . The embodiment can be considered to have three modes of operation: a PIP mode for TV  1 ; a PIP mode for TV  2 ; and a two TV mode. 
     Yet another embodiment is using the PIP mode to allow the viewer of one TV to see what is currently being displayed on the other TV, being recorded, or otherwise delivered to some device other than the TV. In this embodiment, the user of TV  1   210  is watching programming being delivered by channel selector  1   204 . The user gives a command to the STB  202  to display an indicator of what is currently being delivered by channel selector  2   206 , such as for example to TV  2   212 . The indicator could be a simple information screen that overlays the programming displayed on TV  1   210 , the information screen displaying textual information, such as an EPG entry indicating the channel and current programming being delivered by channel selector  2   206 . Alternatively, the indicator could be a PIP display overlaying part of the programming on TV  1   210 , the PIP display showing the current television programming being delivered by the other channel selector. In the PIP embodiment, the PIP display on TV  1   210  and the programming delivered to the other device or TV  2   212  are being simultaneously delivered by the second channel selector  212 . 
     This feature allows a parent to monitor what children are viewing on the other TV, or what children are having recorded. Another use is to periodically monitor the recording of a live event of unknown duration. When used as a parental control, it is also beneficial to allow the user of TV  1   210  to cease or otherwise interrupt the delivery of the second channel of television programming to TV  2   212 . 
       FIG. 3  shows a functional block diagram of another embodiment  300  of an STB  302  in accordance with the present invention capable of independently delivering television programming from an input multi-channel signal  311 , such as signal  110 , to two connected TVs (TV  1   310 , and TV  2   312 ) and in addition provide PIP functionality to either connected TV. In the embodiment, the STB  302  is provided with three channel selectors. Channel selector  1   304  is dedicated to delivering television programming to TV  1   310  and channel selector  2   306  is dedicated to delivering television programming to TV  2   312 . Channel selector  3   308 , however, through a switch  320  may deliver television programming to either TV  1   310  or TV  2   312 . Thus, the embodiment shown in  FIG. 3  may switch between several modes also: two TV mode (wherein channel selector  3   308  is idle); two TV mode with PIP display on TV  1   310 ; and two TV mode with PIP display on TV  2   312 . 
       FIG. 4  presents a slightly more complicated embodiment  400  of an STB  402  that can perform all the functions of the embodiment shown in  FIG. 2  as well as independently support the delivery of television programming stored on an internal storage device  408 , such as a hard drive. In the embodiment, the STB  402  is provided with two channel selectors capable of receiving a multi-channel signal  411  and delivering therefrom a channel of television programming that can be displayed by a connected TV. Both channel selector  1   404  channel selector  2   406  may deliver television programming to either TV  1   410  or TV  2   412  (illustrated by the associated switches  420 ). Thus, similar to the embodiment shown in  FIG. 2 , the embodiment shown in  FIG. 4  may switch between modes including a two TV mode, a PIP mode on TV  1   410 , and a PIP mode on TV  2412 . 
       FIG. 4  also differs from  FIG. 2  by the inclusion of an internal storage device  408  that is connected to both channel selectors  404 ,  406 . In the embodiment shown in  FIG. 4 , a channel selector is required to deliver television programming that has been stored on the storage device  408 . The storage device  408  is connected to both channel selectors such that it is capable of delivering stored television programming to either channel selector. Furthermore, in the embodiment shown the storage device  408  is a hard drive that has sufficiently fast data retrieval support the delivery of stored television programming to both channel selectors allowing the simultaneous viewing of different stored television programming. Thus, the STB  402  in  FIG. 4  may deliver either live or stored television programming completely independently of what is being delivered by the other channel selector. For example, while in a PIP mode a viewer could watch stored television programming on the main display and a second different stored television programming on the PIP display. 
     An additional functionality supported by the embodiment  400  shown in  FIG. 4  is the capability of recording one channel of television programming while simultaneously delivering a different channel of television programming to a connected TV. For example, channel selector  1   404  may be delivering television programming to TV  1   410 , while channel selector  2   406  is simultaneously delivering a different channel of television programming to the storage device  408  for recording. 
     Yet another functionality supported by the embodiment  400  shown in  FIG. 4  is the capability of substantially simultaneously recording television programming on the storage device  408  (which requires using one channel selector to deliver the television programming to the storage device) and retrieving stored television programming from the storage device  408  for delivery to a TV (using the remaining channel selector). It should be noted that some storage devices  408 , such as hard drives, cannot both store and retrieve (i.e. write and read) data simultaneously. However, because of the advances in the speed of hard drives and other storage devices and the availability of buffer memory, it is possible to say, for the purposes of this application, that storage devices can ‘substantially simultaneously’ store and retrieve data. This is because hard drive speeds and the speeds of other comparable storage devices are now so much faster than the speed at which data needs to be delivered to a TV and that it is possible, with the use of one or more temporary buffers, for the storage devices to easily keep up with the required data flow rate in a TV application. Methods and apparatuses of storing and retrieving data from hard drives and other storage devices in such a manner are well known in the art and need not be described here. 
       FIG. 5  illustrates an embodiment  500  of an STB  502  capable of supporting three TVs using three channel selectors that are completely interchangeable. The STB  502  includes three channel selectors  504 , each connected to a multi-channel signal  511 , such as, for example, signal  110 . In the embodiment  500 , each channel selector  504  can be switched so that it delivers television programming to any of the three connected TVs  510 ,  512 ,  514 . Thus, the embodiment  500  shown in  FIG. 5  supports a three TV mode in addition to all the modes described with respect to  FIG. 3 . In addition, the embodiment supports a single TV mode with two PIP displays wherein one channel selector  504  is delivering the main television programming shown on a TV and the other two channel selectors deliver additional channels of television programming as separate PIP displays overlaying the main display. 
     In the embodiments shown in  FIGS. 2 through 5 , the channel selectors are shown as being independently connected to TVs to which they are delivering television programming. It should be noted that alternative embodiments achieve the same functionality by replacing the independent connections with a single data bus that interconnects the channel selectors and the TVs. Such alternative methods of routing the television programming from the channel selectors to the various connected display devices are only variations on means of implementation and are within the scope of the invention. 
     An additional functionality of embodiments of the present invention relates to the performance of housekeeping functions for the device implementing the present invention. As discussed in the background, STBs with a single channel selector typically only perform housekeeping functions when they are ‘off’ as it is assumed that when the STB is on, it is in use. For embodiments of the present invention, the multiple channel selectors support the performance of housekeeping functions at any time, as long as a channel selector is currently not in use delivering television programming. Housekeeping can be considered another mode of operation wherein at least one of the multiple channel selectors is delivering housekeeping information, as may be provided on a designated housekeeping channel, and otherwise performing housekeeping operations. 
     The embodiments were described above as having multiple modes of operation related to what duty each of the channel selectors in any given embodiment were performing. For the broader embodiments, such as that shown in  FIG. 5  wherein each channel selector is independent and completely interchangeable with any other channel selector, each channel selector may be performing any one of the following duties:
         1. Delivering a channel of television programming from the multi-channel signal to any connected TV or other external device;   2. Delivering a channel of television programming from the multi-channel signal, as a PIP display, to any connected TV or other external device;   3. Delivering a channel of television programming from the multi-channel signal to an internal storage device for recording and storage;   4. Delivering a channel of television programming from the internal storage device to any connected TV or other external device;   5. Delivering a channel of television programming from the internal storage device, as a PIP display, to any connected TV or other external device;   6. Performing housekeeping functions; and   7. Idle and standing by for commands.       

     The above list is but one example of the duties that a manufacturer could have an STB perform with a channel selector. Many variations of this list are possible. Thus, embodiments of the present invention may have as many modes of operation as they have channel selectors multiplied by the number of duties each channel selector may perform. 
     Because the embodiments above have different modes of operation, one or more methods for changing between modes are required. The simplest method is a manual switch located on the device. Thus, taking the embodiment in  FIG. 2  as an example, the switch would set the STB  200  to either the PIP mode or the 2 TV mode. A second method is to use a simple protocol that determines which mode will supercede when both are requested. Again taking the embodiment in  FIG. 2  as an example, a command to deliver television programming to TV  2   212  would automatically change the STB  200  from the PIP mode to the 2 TV mode. 
     Yet another method is to provide some inactivity detection means that could determine when a channel selector is idle. Embodiments that include such an inactivity detection means support several additional functionalities by allowing intelligent mode changing. For example, in one embodiment whenever it is necessary to perform housekeeping, the next available channel selector could be used to perform this duty, ‘in the background’ if you will. Thus, the device can be changed into a housekeeping mode without interfering with the subscriber&#39;s use or waiting until the device is turned off. 
     As another example, in other embodiments with an inactivity detection means no channel selectors are allowed to ‘idle’ and stand by for further commands (see item 7, above). Rather, a ‘home’ or favorite channel is selected whenever a channel selector becomes inactive. In some embodiments, this home channel is determined by the user, either by express pre-selection or by the STB based on an analysis of the user&#39;s past viewing habits. In other embodiments, the programming distributor determines the home channel. Yet other embodiments use a combination of the above determination methods. In yet other embodiments, the previous channel viewed is selected. 
     Turning now to  FIG. 6 , the logical steps of an embodiment of a general method  600  of operating a STB with multiple channels selectors and an internal storage device, such as the one illustrated in  FIG. 4 , is presented. The method  600  begins when the STB receives a user command in a receiving step  602  that requires the use of a channel selector to deliver a channel of television programming to a specified TV. Examples of commands that require a channel selector are a ‘change channel’ command (i.e. a command to display a different channel of television programming on a specific TV), a ‘play stored programming’ command (in an embodiment in which a channel selector is required to deliver stored television programming to a TV), a ‘PIP display’ command (to display a second channel of programming as a PIP display on a TV) and a ‘record programming’ command (if the programming to be recorded is not also being displayed). 
     Upon receiving the user command, a determining step  604  determines the channel selectors that are available to perform the command received in the receiving step  602 . In the embodiment, the control electronics of the STB keep track of what duties each of the channel selectors are performing at any given time. Thus, information such as what channel a channel selector currently has selected and where each channel selector is delivering television programming, is readily available for use during the determining step  604 . 
     An example of a simple determining step  604  as applied to the embodiment illustrated in  FIG. 2  would be: use only channel selector  2   206  to deliver television programming to TV  2   212 ; use only channel selector  2   206  to deliver television programming as a PIP display to TV  1   210 ; if channel selector  1  is not performing housekeeping functions, use channel selector  1  for delivering television programming to TV  1   210 ; if channel selector  1  is performing housekeeping functions and TV  2  is not in use, use channel selector  2  to deliver television programming to TV  1 ; and if channel selector  1  is performing housekeeping functions and TV  2  is in use, stop performing housekeeping functions and use channel selector  1  to deliver television programming to TV  1 . 
     Based on results of the determining step  604 , allocating step  606  allocates a channel selector to deliver the programming necessary to execute the command received in receiving step  602 . Once a channel selector has been allocated, delivering step  608  delivers the programming necessary to execute the command received in the receiving step  602  using the allocated channel selector. 
       FIG. 7  presents the logical steps of a more detailed method  700  of operating a STB with multiple channels selectors and an internal storage device. As in the general method  600 , the method  700  begins when the STB receives a user command in a receiving step  702  that requires the use of a channel selector to deliver television programming. Next, a determination step  704  determines if the channel of programming requested by the user in the receiving step  702  is already selected by a channel selector. 
     There are several situations where this may occur. The user command may be to request delivery of a channel that is already being delivered to another TV or to the storage device. In addition, the user command may be to deliver a predetermined ‘home’ or favorite channel that channel selectors automatically select when idle or not otherwise directed to select specific channels as discussed above. If the determination step  704  determines that the requested channel is being delivered, then the allocating step  706  allocates the channel selector already delivering the channel of programming to deliver the programming necessary to execute the command received in the receiving step  702 . In this situation, the allocated channel selector will be delivering television programming to more than one device simultaneously. 
     If the requested channel of programming is not already being delivered by a channel selector then a second determination step  708  determines if there is an idle channel selector available for allocation. If there is an idle channel selector available, allocation step  710  allocates an idle channel selector to deliver the programming necessary to execute command received an Receiving step  702 . If the second determination step determines that there is no idle channel selector available, in the embodiment illustrated, the channel selector currently delivering television programming to the user&#39;s TV is allocated by a third allocation step  712  to deliver the requested channels of programming received in the receiving step  702 . Regardless of which channel selector is allocated, once a channel selector is allocated the delivering step  714  delivers the requested channel of television programming completing the execution of the command received in the receiving step  702 . 
     The detailed method  700  decreases the amount of time necessary to perform a change channel command and thus reduces the amount of tuner delay perceived by the user. By preferentially using the channel selector that is already delivering the desired channel, when such a channel selector is available, there is no tuner delay. Although it may take the electronics a finite amount of time to switch the data delivered to the TV, the delay will be far less than that associated with tuning to or selecting a new channel. Also, by preferentially using a channel selector other than the one currently delivering programming to the TV, the user will not experience a period during which the TV receives no television programming. Thus, method  700  reduces the user&#39;s perception of tuner delay. 
       FIG. 8  presents the logical steps of a method  800  of performing housekeeping operations on a STB with multiple channels selectors and an internal storage device. The STB determines when it is necessary to perform housekeeping in the determination step  802 . This determination can be made based on the passage of time or can be in response to a condition of the STB or can be initiated by remote command, such as the receipt of a signal the new software is available from the television programming distributor. When it is determined that a housekeeping function needs to be performed and the housekeeping function requires the use of a channel selector, determining step  804  determines the channel selectors that are available to perform the necessary housekeeping function. Based on results of the determining step  804 , allocating step  806  allocates a channel selector to deliver the channel comprising the housekeeping information necessary to perform housekeeping functions. Once a channel selector has been allocated, an execution step  808  uses the allocated channel selector to select the channel comprising the housekeeping information and deliver it to an appropriate internal device for the execution of the housekeeping function. This device maybe the temporary buffer, the storage device, or the control electronics as necessary for the execution of the housekeeping function. 
       FIG. 9  presents the logical steps of an embodiment of a method  900  of operating a STB with an internal storage device and multiple channels selectors, wherein one of the channel selectors has a substantially shorter tuner delay (i.e. it is substantially faster at selecting a new channel and delivering television programming from it). Similar to the method shown in  FIG. 6 , the method reduces tuner delay perceived by the user, but this time by preferentially using the fast channel selector to perform all channel change commands wherever possible. 
     As  FIG. 9  shows the method  900  begins with the receipt of a user command, in a receiving step  902 , that requires the use of a channel selector to deliver a channel of television programming. Next, a determination step  904  determines if the channel of programming requested by the user in the receiving step  902  is already selected by a channel selector. If the determination step  904  determines that the requested channel is already being delivered, then the allocating step  906  allocates the channel selector already delivering the channel of programming to deliver the programming necessary to execute the command received in the receiving step  902 . In this situation, the allocated channel selector will be delivering television programming to more than one device simultaneously. 
     If the requested channel of programming is not already being delivered by a channel selector, then a second determination step  908  determines if the fast channel selector is available for allocation. If the fast channel selector is available, then a second allocation step  910  allocates the fast channel selector to be used to execute in the command received by the receiving step  902 . If the fast channel selector is not idle and available for allocation, then in the embodiment illustrated a third allocating step  912  allocates the channel selector currently delivering television programming to the user&#39;s TV. Regardless of which channel selector is allocated, once a channel selector is allocated the delivering step  914  delivers the requested channel of television programming to the user&#39;s TV. 
     The method  900  then continues with a third determination step  916  that determines if there are any remaining channel selectors idle and available. If there are no idle channel selectors, then no further action is taken under this method  900 . This situation may occur if all of the channel selectors on the STB are active and delivering programming at time to receiving step  902  receives the user command. However, if there is an idle channel selector available to be allocated, a fourth allocation step  918  allocates an idle channel selector to also execute the command received in the receiving step  902 . 
     After the allocation of the fourth allocation step  918 , a transition step  920  transitions delivery of the television programming from the fast channel selector to the second allocated channel selector allocated in the fourth allocation step  918 . As part of the transition step  920 , care is taken to ensure no interruption in television programming is perceived by the user. The transition step  920  also includes reallocating the fast channel selector leaving it available for use in subsequent channel changes. By preferentially leaving the fast channel selector available as much as possible, the method  900  effectively uses the single fast channel selector to reduce tuner delay as much as possible. 
     The methods shown in  FIGS. 6 through 9  are provided as examples to aid the reader&#39;s understanding of how the embodiments of the present invention might be operated. It will be obvious to the reader that the methods above are only generally presented and, depending on the exact embodiment of the present invention to which they are applied, may vary in differing amounts. Furthermore, as the methods are very suitable for implementation as software running on a processor within the control electronics, the exact algorithm used may be very different while achieving essentially the same results of choosing a channel selector from among several to effectuate a user command to deliver programming.