Patent Publication Number: US-2003233667-A1

Title: Method and apparatus for implementing a scaled upgrading of an upgradeable set-top box

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] This invention relates to broadband communications systems involving both terrestrial and satellite digital television transmission and digital cable television transmission.  
       [0003] 2. Background Art  
       [0004] Digital television transmission technology shall be the de-facto transmission format in the very near future. In the United States, more and more stations are converting to the digital format of transmission to take advantage of the clarity of reception and to make use of the wide pipeline made available to distribute information which includes video, sound, and data. Transmission of digital visual and aural signals can be made via terrestrial systems or cable/broadband systems. Digital set-top boxes are used to receive the signals and subsequently provide output signals to an attached television receiver or stereo system.  
       [0005] In developing countries, however, the high cost of existing digital set-top boxes makes them too expensive for the majority of the viewing public. Such digital boxes have been originally designed to cater to customers in highly developed countries hence, additional “bells and whistles” or add-on features are typically included in the design to maximize its use inside the home. These features may include but are not limited to electronic program guides and internal memory to provide pausing and limited rewind functions, all for the convenience of the viewer. However, all these features add more costs in manufacturing the box and inevitably lead to a more expensive set-top box for the consumers. To this end, basic set-top boxes have been made available to viewers.  
       [0006] Generally, basic set-top boxes are designed with only the minimum circuitry needed to receive digitally formatted transmissions. While these basic set-top boxes satisfy the immediate need to deliver digital television signals at the most cost-effective method, their usefulness is lost as the entertainment and information needs of the viewer become more sophisticated. More to the point, when viewers wish to take advantage of the additional features available through broadband communications, they are typically required to replace their basic set-top box with a more sophisticated appliance. Consequently, the investment made in purchasing the basic set-top box is lost.  
       [0007] There is, therefore, a need for a set-top box whose features may be upgraded and expanded over time. In this way, features can be initially removed from the basic set-top to bring the cost of the box down to its barest minimum. As the financial resources of the viewer increase and his entertainment and information needs become more sophisticated, the set-top box can be upgraded and expanded, thereby avoiding the loss of the initial investment made in the set-top box.  
       BRIEF SUMMARY OF THE INVENTION  
       [0008] In an embodiment, the invention includes a method and apparatus for an upgradeable set-top box that provides for the reception of digital television signals conforming to either the Digital Video Broadcasting (DVB) or Advanced Television System Committee (ATSC) method of digital transmission. The upgradeable set-top box of the present invention is further able to receive standard television signals conforming to National Television Standards Committee (NTSC), Phase Alternation Line (PAL) or Sequential Couleur avec Memoire (SECAM) color systems. Still further, in an embodiment, the present invention is able to provide the following services: cable telephony, cable modem, web-based internet-over-TV, multi-channel digital audio, and prepaid options for the above-mentioned services.  
       [0009] In specific terms, the invention enables the reception of digital television signals from a digital television source that can be categorized as a terrestrial, satellite or broadband (cable television) broadcaster. In accordance with embodiments of the present invention, an upgradeable set-top box is connected to an aerial antenna which will receive the digital terrestrial signals from the broadcaster and in turn converts the received digital signals into standard NTSC, PAL, or SECAM RF signals or composite video signals ready to be fed to a standard compatible television receiver or monitor. In this way, the upgradeable set-top box provides digital receiver functionality to existing television sets hence lowering the cost of digital television reception.  
       [0010] As the capability of the viewer to spend increases, the upgradeable set-top box can be upgraded with the addition of an upgrade module. Once the upgrade module is added, the upgradeable set-top box can be appropriately viewed as an upgraded set-top box. The upgrade module provides additional features to the set-top box. For example, in an embodiment, the upgrade module provides remote tuning capability to the upgraded set-top box. The choice of channels to be viewed shall be fully controlled from a universal remote control. This would eliminate the use of separate controls for each different device.  
       [0011] In another embodiment, the upgrade module provides the capability for the upgraded set-top box to be connected to a cable television system. When the viewer enrolls in a subscription cable television service, the upgraded set-top box is “cable ready,” hence no additional set-top converter is required. In accordance with this embodiment, internal circuitry in the upgraded set-top box shall have integrated A/B switch functionality so that viewers can switch from terrestrial digital/analog transmissions or cable television reception.  
       [0012] In yet another embodiment, a prepaid section is incorporated in the upgrade module to provide prepaid card functionality to the upgraded set-top box. This would enable the reception of digital pay channels that are also transmitted together with the free-to-air digital signals. With digital transmission, more than two standard definition channels can be received by the upgraded set-top box. Thus, the extra pay television digital channels can be distributed and received upon authorization by a prepaid card system.  
       [0013] In another embodiment, the upgraded set-top box can be further augmented by an expansion box that is removably attachable to the upgraded set-top box. In accordance with this embodiment, the expansion box is designed with expansion slots in which expansion modules providing additional and new services can be installed. The expansion modules could be, for example, expansion cards or similar devices which can be plugged into the expansion slots to provide additional functionality.  
       [0014] In another embodiment, the expansion box contains an integrated power supply section that will provide power to the upgraded set-top box and the additional expansion modules that may be installed.  
       [0015] The upgraded and expanded set-top box when used in a two-way cable television/broadband network can now deliver new and additional services depending on the expansion modules installed. Single expansion cards or a combination of a number of cards can be installed to provide the different services that are available from the broadband network.  
       [0016] Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES  
     [0017] The accompanying drawings illustrate the present invention and together with the description, further serve to explain the principles of the invention and to enable a person skilled in the relevant art to make and use the invention. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears.  
     [0018]FIG. 1A provides an exemplary external front view of an upgradeable set-top box according to an embodiment of the present invention.  
     [0019]FIG. 1B provides an exemplary external back view of an upgradeable set-top box and attachable power adaptor according to an embodiment of the present invention.  
     [0020]FIG. 2 provides an exemplary block diagram of an upgradeable set-top box and its electrical functions according to an embodiment of the present invention.  
     [0021]FIG. 3A provides an exemplary external front view of an upgrade module for upgrading the functions of an upgradeable set-top box according to an embodiment of the present invention.  
     [0022]FIG. 3B provides an exemplary external back view of an upgrade module for upgrading the functions of an upgradeable set-top box according to an embodiment of the present invention.  
     [0023]FIG. 4 provides an exemplary block diagram of an upgrade module and its electrical functions when coupled to an upgradeable set-top box according to an embodiment of the present invention.  
     [0024]FIG. 5A provides an exemplary external front view of an expansion box for expanding the functions of an upgradeable set-top box according to an embodiment of the present invention.  
     [0025]FIG. 5B provides an exemplary external rear view of an expansion box for expanding the functions of an upgradeable set-top box according to an embodiment of the present invention.  
     [0026]FIG. 6 provides an exemplary block diagram of an expansion box for expanding the functions of an upgradeable set-top box according to an embodiment of the present invention.  
     [0027]FIG. 7 provides exemplary external views of the expansion modules used in conjunction with an expansion box according to an embodiment of the present invention.  
     [0028] FIGS.  8 A- 8 B illustrate an exemplary method of upgrading the functions of an upgradeable set-top box using an upgrade module according to an embodiment of the present invention.  
     [0029] FIGS.  9 A- 9 C illustrate a method of expanding the functions of an upgradeable set-top box using an expansion box according to an embodiment of the present invention.  
     [0030] FIGS.  10 A- 10 B illustrate an exemplary method of expanding the functions of an expansion box according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0031] I. Upgradeable Set-Top Box  
     [0032] Referring to FIG. 1A, in an embodiment, the upgradeable set-top box  100  is comprised of a housing  105 , a display  140 , an upgrade slot  141 , and one or more function access buttons  115 . In an embodiment, the display  140  is a LED display and is used to visually communicate the status of the upgradeable set-top box  100  to a viewer. The upgrade slot  141  is an open area within the upgradeable set-top box  100  that is used to receive an upgrade module (described further below). The function access buttons  115  are provided for a user to selectively operate the upgradeable set-top box  100 . For example, the function access buttons  115  could be used to power the upgradeable set-top box  100  on and off or tune the upgradeable set-top box  100  to different channels.  
     [0033] Referring to FIG. 1B, in an embodiment, the upgradeable set-top box  100  is further provided with a plurality of audio-video ports  143 . The audio-video ports  143  provide the upgradeable set-top box  100  with the ability to receive and transmit audio and video signals. A number of radio frequency (RF) ports  142  are also included with the upgradeable set-top box  100 . In the present embodiment, three ports are provided for antenna input, cable television input, and RF output to a television set. A power input port  144  is used to provide power to the upgradeable set-top box  100  using for example, an external power supply adaptor  120 . The external power supply adaptor  120  can be acquired separately and used to power the upgradeable set-top box  100 . In the present embodiment, the output of external power supply adaptor  120  is in DC form and corresponds to the voltage and power requirements of the upgradeable set-top box  100 . A channel output selector  145  is used to selectively choose the channel output over which a viewer will watch the received broadcast signals using a standard broadcast television receiver. When necessary, an upgradeable set-top box expansion port  146  is available to couple the upgradeable set-top box  100  to an expansion box. Exemplary internal components of the upgradeable set-top box  100  of the present invention will now be described with reference to FIG. 2.  
     [0034] In an embodiment, the upgradeable set-top box  100  is further comprised of a signal splitter  203 , and an upgradeable set-top box tuner/receiver section  205 . The upgradeable set-top box tuner/receiver section  205  can be compliant with DVB-T, ATSC, or other standards depending on the type of technology adopted by the broadcaster. A de-scrambler  207  is provided to enable the reception of basic digital signals. A routing matrix  214  provides for the proper routing of the audio-video signals. This is particularly important when the functions of the upgradeable set-top box  100  are upgraded and/or expanded in accordance with embodiments of the present invention. More to the point, as upgraded and expanded functions are added, the electronic signals corresponding to those functions will need to be correctly routed to and from the appropriate modules.  
     [0035] An RF modulator  218  is provided to enable the upgradeable set-top box  100  to be connected to a standard television set. In an embodiment, the RF modulator  218  is tuned to a standard television channel selected via the channel output selector  145  (FIG. 1B). In another embodiment, the RF modulator  218  can be replaced with a Phase Alternating Line (PAL) compliant counterpart as required by the end user. Additional features of the upgradeable set-top box  100  will be described further below with reference to an exemplary implementation. To continue, in accordance with another embodiment of the present invention, an exemplary upgrade module  347 , will now be described with reference to FIG. 3.  
     [0036] II. Upgrade Module  
     [0037] The upgrade module  347  is used to provide the upgradeable set-top box  100  with additional functions. The upgrade module  347  is provided with a smart card slot  348  on a front face or portion  345  thereof. In accordance with embodiments of the present invention, the smart card slot  348  is used to receive prepaid smart cards. An infrared (IR) port  349  is also provided on the front face  345  for wireless remote control functionality. The back face or portion  346  of the upgrade module  347  is provided with interface connectors which will mate with corresponding ports (not shown) on the upgradeable set-top box  100 . In the present embodiment, the RF connectors  350  and  351  provide for the input and output of RF signals between the upgradeable set-top box  100  and the upgrade module  347 . An edge connector  352  provides for the exchange of power, audio, video, and other non-RF signals exchanged between the upgrade module  347  and the upgradeable set-top box  100 . Exemplary internal components of the upgrade module  347  will now be described with reference to FIG. 4.  
     [0038] In an embodiment, the upgrade module  347  is designed to be inserted into the upgradeable set-top box  100 . In this way, additional functionality for the combined devices is achieved. In the present embodiment, the upgrade module  347  includes an A/B switch  424  that can select what input the combined devices will process. The A/B switch  424  is also used for exchanging RF signals  423  with an expansion box used to expand the functionality of upgradeable set-top box  100 . A prepaid card reader section  427  allows for a user of the combined upgradeable set-top box  100  and upgrade module  347  to access prepaid functions via the combined devices. The prepaid card reader section  427  is provided with computer programs (also called computer control logic) to determine the level of service the combined upgradeable set-top box  100  and upgrade module  347  can receive based on the amount of credit available on a removable SIM (Subscriber Identity Module) card to be inserted. An upgrade module tuner receiver section  429  is also provided. In the present embodiment, the upgrade module tuner receiver section  429  is a VHF/UHF/Cable TV tuner. The upgrade module tuner receiver section  429  allows the combined upgradeable set-top box  100  and upgrade module  347  to receive off-air VHF and UHF television signals as well as cable television channels. A remote control section  437  and the corresponding infrared pickup port  349  provide remote control functions to the upgradeable set-top box  100 . The remote control section  437  receives command signals from a remote control and transmits corresponding signals to control the upgradeable set-top box tuner/receiver section  205 , routing matrix  214 , A/B switch  424 , and the upgrade module tuner/receiver section  429 . The remote control section  437  is further useful for accessing and controlling the additional functions provided by attaching the upgradeable set-top box  100  to an expansion box (described in detail further below). Once attached, control signals  436  can be transmitted to the expansion box. Likewise, infrared signals  435  can be received via an infrared port. Additional features of the upgrade module  347  will be described further below with reference to an exemplary implementation.  
     [0039] As the entertainment and information needs of the viewer become more sophisticated, an expansion box  500  is designed to be removably attachable to the upgradeable set-top box  100 . In this way, additional functionality may be achieved without making the upgradeable set-top box  100  obsolete. An exemplary external view of an expansion box  500 , configured in accordance with embodiments of the present invention, will now be described with reference to FIGS. 5A and 5B.  
     [0040] III. Expansion Box  
     [0041]FIG. 5A shows a front perspective view of an embodiment of the expansion box  500 . Expansion box  500  has an insert slot  567  provided on a front face  502 . In the present embodiment, the insert slot  567  is a loading bay/slot. In this way, the expansion box  500  can be removably connected to the upgradeable set-top box  100  by sliding the upgradeable set-top box  100  into the insert slot  567  of the expansion box  500 . By slidably attaching the expansion box  500  and the upgradeable set-top box  100 , mechanical stability is achieved. After reading this disclosure, a person skilled in the relevant arts will recognize alternative methods of attaching the expansion box  500  and the upgradeable set-top box  100  without departing from the spirit and scope of the present invention.  
     [0042] The expansion box  500  is further provided with a display  564  on the front face  502 . The display  564  is used to show the status of the expansion box  500 . In an embodiment, the display  564  is a wide-screen LCD display. Expansion box function access buttons  563  are provided on front face  502  for menu navigation. Together, the display  564  and the expansion box function access buttons  563  allow different services to be accessed and any required set-up options to be inputted.  
     [0043] An access panel  568  provides accessibility to the ports of the upgradeable set-top box  100  when attached to a rear face  504  of the expansion box  500 . Further, expansion box  500  has a connection port  566  on the rear face  504  for connecting to the expansion port  146  on the upgradeable set-top box  100 . An expansion module access panel  565 , also disposed on the rear face  504 , can be removed to expose the ports of one or more expansion modules installed inside the expansion box  500 . Further details of the expansion box  500  will now be provided with reference to FIG. 6.  
     [0044] In an embodiment, the expansion box  500  is provided with one or more expansion slots  654 . A plurality of bus connections  653  are used for exchanging communications among the expansion modules  650  and other set-top box components, such as for example, a microprocessor  634 . The expansion modules  650  are inserted into one of the expansion slots  654  to expand the functions of the expansion box  500  and upgradeable set-top box  100 . Self-terminating RF splitters (not shown) are used to detect when an expansion module  650  is present within one of the expansion slots  654 . In the present embodiment, the self-terminating RF splitters are terminated to 75 ohms when no expansion module  650  is inserted. The expansion modules  650  are described in further detail below with respect to FIG. 7.  
     [0045] An on-screen display section  656  provides on-screen display functionality to the combined upgradeable set-top box  100  and expansion box  500 . The on-screen display section  656  is responsible for composing information to be displayed on a monitor or television screen. Such information can include for example, the digital or analog channel that the box is tuned to, an electronic program guide, web pages, and other related information. In the present embodiment, the on-screen display section  656  receives as its input, the auxiliary video signal  430  which originates from the upgrade module  347  and the auxiliary video signal  209  from the descrambler  207 . The microprocessor  634  is added to provide computer program logic to the combined upgradeable set-top box  100  and expansion box  500 . The computer program logic of the microprocessor  634  and its ability to control the additional functionality provided by the expansion modules  650  is supported by the on-board expansible memory  655 . An integrated power supply  657  is also included. In this way, power can be provided to the expansion box  500 , the upgradeable set-top box  100 , and the upgrade module  347 . The present embodiment would then allow for external power supply adaptor  120  to be discarded or used for other purposes.  
     [0046]FIG. 7 illustrates the different expansion modules  650  that could be used with the expansion box  500  in accordance with embodiments of the present invention.  
     [0047] An internet-over-television module  758  provides internet browsing using only a television set and an optional IR wireless keyboard.  
     [0048] A cable modem module  759  enables the combined expansion box  500  and upgradeable set-top box  100  to perform cable modem functions. An Ethernet port  770  is provided for connection to a personal computer.  
     [0049] A telephony module  760  provides telephone functionality to the combined expansion box  500  and upgradeable set-top box  100 . Two telephone ports  771  are provided for connection to standard analog telephone sets.  
     [0050] A digital multi-channel audio module  761  enables the combined expansion box  500  and upgradeable set-top box  100  to receive multi-channel stereophonic audio signals and connect them to a stereophonic component audio system. To facilitate such a connection, stereo RCA jacks  768  are provided.  
     [0051] In the present embodiment, the underside portion of the expansion module  650  is designed with connectors that will mate with corresponding ports on the expansion box  500 . Specifically, an RF connector  773  enables the transfer of RF signals from the expansion box  500  into the expansion module  650 . An edge connector  772  provides for the interchange of non-RF signals between the expansion module  650  and the expansion box  500 . Further, in the present embodiment, each expansion module  650  (for example, modules  758 ,  759 ,  760 , and  761 ) are provided with a dual color led  769  to indicate operation status.  
     [0052] The above described modules are meant for example only, and not limitation. More generally, the bus architecture of the expansion box  500  would enable further expansion modules of specific functions to be installed in the future. One such future expansion module  650  could be a modular card that would provide recording of received television programs on a built in RAM drive. Video of more than two hours can be stored in an appropriate storage medium in the modular card and can be played back later. Upon reading this disclosure, a person of ordinary skill in the relevant arts will recognize that this and other future broadband-based applications or services yet to be developed can be included by designing the compatible expansion card to be attached to the expansion box  500 . This flexibility inherent in the present invention makes the combined expansion box  500  and upgradeable set-top box  100  a very versatile device.  
     [0053] IV. Exemplary Method for Upgrading and Expanding  
     [0054] FIGS.  8 A- 10  provide an exemplary illustration of a method for upgrading and expanding the functionality of the upgradeable set-top box  100  in accordance with an embodiment of the present invention.  
     [0055] First, as shown in FIG. 8A, an upgrade module  347  is inserted into the upgrade slot  141  of the upgradeable set-top box  100 . This produces an upgraded set-top box  800  as shown in FIG. 8B. The upgrade module  347  provides the upgraded set-top box  800  with additional functionality previously unavailable in the upgradeable set-top box  100 . In accordance with embodiments of the present invention, this increased functionality is realized without having to replace the upgradeable set-top box  100 . As the information and viewing needs of the user become more sophisticated, the functionality of the upgraded set-top box  800  can be further enhanced using the expansion box  500 .  
     [0056] Referring to FIG. 9A, the upgraded set-top box  800  is shown being inserted into the insert slot  567  of the expansion box  500 . This produces an upgraded and expanded set-top box  900  as shown in FIG. 9B. As illustrated in FIG. 9C, the access panel  568  is removed to expose the audio-video ports  143 , RF ports  142 , channel output selector  145 , power input port  144 , and expansion port  146 .  
     [0057] Once the upgraded set-top box  800  has been inserted into the expansion box  500 , a connector  979  is used to attach expansion port  146  and connection port  566 . In an embodiment, the connector  979  is a multi-core jumper cable. The connector  979  is used to isolate the RF signals as well as to control the audio and video signals being exchanged between the expansion box  500  and upgraded set-top box  800 . In yet another embodiment, the functionality of the upgraded and expanded set-top box  900  can be further enhanced by expanding the features of the expansion box  500 .  
     [0058]FIGS. 10A and 10B provide an exemplary illustration of a method for expanding the functionality of the expansion box  500  in accordance with an embodiment of the present invention. The expansion module access panel  565  is opened to allow a peripheral device (for example, telephones, stereophonic components, and computers) to be connected to the expansion module  650  once the expansion module has been inserted.  
     [0059] Next, an expansion module  650  (for example, module  758 ,  759 ,  760 , or  761 ) is inserted into one of the expansion slots  654 . In the present embodiment, four expansion modules ( 758 ,  759 ,  760 , and  761 ) are shown in the expansion box  500 . Upon reading the disclosure, a person skilled in the relevant arts would recognize that one or more of the expansion modules can be added as needed. In this way, the functionality expansion can be scaled according to the needs and financial resources of the viewer. Continuing, once an expansion module  650  is inserted, the electrical output of the RF splitter would be adjusted to reflect the presence of the expansion module  650 . Once connected, the upgraded and expanded set-top box  900  can be set-up to use the newly added function.  
     [0060] With the expansion box  500  attached to the upgraded set-top box  800 , the viewer can take advantage of the different types of broadband services that can be made available through the single box design of the present invention. Hence, the investment in the upgradeable set-top box is maximized. For example, the Internet-Over-TV expansion module  758  can be added to enable the viewer to surf into World Wide Web pages with a built-in browser. In an embodiment, the browser is designed to be download upgrade-able. The browser allows a cable television headend-based server to deliver internet content to the subscriber to be viewed on the subscriber&#39;s television set. Further, with the use of a wireless keyboard via the infrared receiver port of the remote control, email downloading can be made possible using memory cached on the service provider&#39;s servers. Likewise, the remote control further enables the viewer to click hypertext links on the television screen. Consequently, the expansion module  650  should be compatible with the cable headend system to provide two-way communication over the air.  
     [0061] In accordance with the present embodiment, a cable modem expansion module  759  could also be added. In the present embodiment, the cable modem expansion module  759  is a DOCSIS compliant device enabled for use with a personal computer while the upgraded and expanded set-top box  900  is used to receive analog or digital television signals. Accordingly, corresponding output ports are included on the expansion modules or cards to be connected to a personal computer for internet communications. By maximizing the available bandwidth in the broadband network that the combined upgraded set-top box and expansion box are connected to, higher download speeds are obtainable.  
     [0062] An IP telephony expansion module  760  can be installed to meet the need for a second or third telephone line. IP Telephony enables the upgraded and expanded set-top box  900  to perform the functions of a network interface card providing telephone functionality. Through IP transmission, voice packets can be sent and received through the upgraded and expanded set-top box  900 , thereby providing additional functionality to the device. Two telephone line ports are provided where analog telephone sets can be connected. In accordance with this embodiment, the computer program logic needed to convert the analog telephone signals is designed into the ILP telephony expansion module  760 . Similar to the cable modem, this expansion module can operate independently from the television reception functions of the upgraded and expanded set-top box  900 .  
     [0063] Lastly, the multi-channel digital stereo audio expansion module  761  can be designed to provide for the reception of multiple channels of stereophonic audio which can be monitored in the television set or connected to an external sound/speaker system. More specifically, multi-channel digital audio enables the upgraded and expanded set-top box  900  to function as a multiple channel digital stereo audio receiver that converts received digital audio signals into baseband stereo audio ready to be fed to an audio system. Given the wide bandwidth available in the broadband system and advances in data compression techniques, additional pay audio channels can be made available to subscribers who have varied musical tastes.  
     [0064] Likewise, additional audio information can be displayed on the television set which includes but is not limited to artist information, song, lyrics and purchase information. Still further, developments in Bluetooth™ wireless technology can be implemented to minimize the use of connecting cables between the upgraded and expanded set-top box  900  and a conventional audio stereo system. Bluetooth™ wireless technology is a wireless communications standard promoted by a trade association operating under the name Bluetooth SIG, Inc.  
     [0065] It is further emphasized that future broadband services yet to be developed can be incorporated into the expansion box  500  by designing the corresponding compatible expansion module. The upgrade path from upgradeable set-top box  100  to upgraded set-top box  500  to upgraded and expanded set-top box  900  to modular card-based service expansions and similar advancements provides for a gradual upgrade of the set-top box based on the capacity of the viewer/subscriber to spend for his entertainment and/or information needs. An exemplary implementation of the present invention will now be described with reference to the above described figures.  
     [0066] V. Exemplary Implementation  
     [0067] Referring again to FIG. 2, input signals  201  are received by an external antenna and are then fed into the upgradeable set-top box  100 . The signal splitter  203  divides the signals into two signal streams. A first signal stream  202  is initially terminated for future feeding to the upgrade module  347 . A second signal stream  204  is fed to the upgradeable set-top box tuner/receiver section  205  of the upgradeable set-top box  100 .  
     [0068] The upgradeable set-top box tuner/receiver section  205  generates a tuner output signal  206 . In the present embodiment, the tuner output signal is an encrypted digital signal. The tuner output signal  206  is next fed to the de-scrambler section  207  which converts the encrypted digital signal into a standard stereophonic audio signal  210  and baseband video signal  211 . An auxiliary video signal  209  and an auxiliary signal  208  are initially terminated for future use when the upgradeable set-top box  100  has been upgraded.  
     [0069] The standard stereophonic audio signal  210  and the baseband video signal  211  are then fed to the routing matrix  214 . The routing matrix  214  will determine how the signals are routed between the inputs and outputs. When the upgrade module  347  is not yet in place, the default routing input of the routing matrix  214  shall be the stereophonic audio signal  210  and the baseband video signal  211  from the descrambler  207 .  
     [0070] The routing matrix  214  will output the stereophonic audio signal  210  and baseband video  211 . These outputs can be fed through RCA-type output ports to an external television monitor having audio and video inputs at the back of the monitor. Signals  431 ,  432 ,  436 , and  674  are initially terminated for future use once the upgradeable set-top box  100  has been upgraded or expanded. These signals will be described in further detail below.  
     [0071] Continuing with the present description, another set of stereophonic audio signals  216  and baseband video  217  outputs are fed to the RF Modulator  218 . The RF Modulator  218  then converts these signals into an RF modulated signal  219 . The RF modulated signal  219  can serve as input to the antenna input of a television set through F-type RF ports found at the back of the appliance. This is useful for older model broadcast televison sets that do not have RCA-type audio and video inputs.  
     [0072] According to the present embodiment, in non-upgraded form, the upgradeable set-top box  100  is capable of receiving digital television signals and converting these signals into a compatible form that can be fed into a video monitor and/or television set. With minimal circuit components and practical absence of features, the upgradeable set-top box  100  is expected to cost within the reach of middle class television viewers.  
     [0073] Referring again to FIG. 4, the next stage of upgrade for the upgradeable set-top box  100  shall be the insertion of the upgrade module  347  into the upgrade slot  141  of the upgradeable set-top box  100 . This produces the upgraded set-top box  800 . In the present embodiment, the upgrade module  347  can receive input from two possible sources: the first signal stream  202  or a cable input  421 . Both inputs are attached to the A/B switch  424  in order to facilitate the selection and isolation of the two signals. In an embodiment, the A/B switch can be electronically controlled through control signals  425  generated from the prepaid card reader section  427 . Depending on the card inserted into the card reader section, the cable input signal can be disabled thereby preventing reception of cable television signals. The A/B switch output  426  is fed to the upgrade module tuner/receiver section  429 .  
     [0074] The upgrade module tuner/receiver section  429  generates a tuner section audio signal  431  and video signal  432 . The tuner section audio signal  431  and video signal  432  are each fed to the routing matrix  214  of the upgraded set-top box  800 . When analog reception is selected, the upgraded set-top box  800  will route the signal to the monitor and/or television outputs of the upgraded set-top box  800 .  
     [0075] In the present embodiment, the upgraded set-top box  800  shall have remote control features for the convenience of the viewer. Furthermore, with the analog tuner of the upgrade module  347 , all VHF, UHF and Cable Television channels can now be received by the box. Hence, there would be a single remote controller that can be used to watch either the digital or analog signals. Furthermore, the inclusion of the prepaid card reader section  427  provides prepaid functions to the upgraded set-top box  800 . Accordingly, prepaid signals  428 ,  475 , and  476  are used to authorize cable television services and digital terrestrial services on a prepaid basis. The inclusion of the upgrade module  347  further enables the upgraded set-top box  800  to receive wireless signals  435  from a wireless keyboard via the infrared ports also utilized by the remote control. In response to receiving the wireless signals, the remote control section  437  generates corresponding control signals  436  for input to the appropriate component (for example, the routing matrix  214 , the upgradeable set-top box tuner/receiver section  205 , upgrade module tuner section  429 , the A/B switch  424 , or an on screen display section  656 ). A control signal  436 , RF signals  423 , and auxiliary video signal  430  are initially terminated until the upgraded set-top box  800  has been joined with the expansion box  500 .  
     [0076] As the entertainment and information needs of the viewer become more sophisticated, the expansion box  500  can be attached to the upgraded set-top box  800 . In this way, additional functionality is achieved without making the upgradeable set-top box  100  obsolete. The expansion box  500  makes the integrated/combined boxes capable of accepting additional expansion modules for other value added services such as television internet, cable modems, cable telephone over IP and multi-channel digital audio reception.  
     [0077] Referring again to FIG. 6, RF signals  423  originating from the upgrade module  347  are split and distributed among the appropriate expansion modules  650  via the bus  653 .  
     [0078] The on-screen display section  656  receives as input, the auxiliary video signal  430  from the upgrade module  347  and the auxiliary video signal  209  from descrambler  207 . The on-screen display section  656  is further capable of receiving as input, the control signal  436  from the remote control section  437  initially terminated at the upgrade module  347 .  
     [0079] The microprocessor  634  provides overall control over the different sections within the expansion box  500 . Control lines  667  are used to exchange control information between the microprocessor  634  and the expansible on-board memory  655 , the on-screen display section  656  and the expansion modules  650  via the expansion slots  654  and bus connections  653 .  
     [0080] On-screen display section  656  next produces the video signal  674 . The video signal  674  is then fed back to the routing matrix  214  for eventual switching to the designated television or stereo system output.  
     [0081] VI. Conclusion  
     [0082] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only and not limitation. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.