1. A method of controlling a virtual channel for building a channel map in an internet protocol television (IPTV) receiver, the method comprising:
receiving a master service information (SI) table including a first element defining location of a virtual channel map table;
parsing the first element in the received master SI table;
receiving the virtual channel map table including a second element defining location of a virtual channel description table based on the parsed first element and a first service identifier for identifying a virtual channel;
parsing the second element in the received virtual channel map table;
receiving the virtual channel description table based on the parsed second element, wherein the virtual channel description table includes a second service identifier;
determining whether a third element is omitted in the virtual channel description table, wherein the third element indicating designation of times when a virtual channel identified by the second service identifier is active, wherein the third element includes at least one of start time and end time;
determining the virtual channel identified by the second service identifier is always active, if the third element is omitted in the virtual channel description table;
parsing the third element in the received virtual channel description table if the third element is not omitted in the virtual channel description table;
determining whether the virtual channel identified by the second service identifier is inactive or active from the parsed third element, if the third element is not omitted in the virtual channel description table; and
controlling display of the virtual channel according to the parsed third element,
wherein details information of the virtual channel identified by the first service identifier corresponds to details information thats second service identifier is equal to the first service identifier,
wherein the second element is a default location, which is corresponding to every virtual channel in the channel map table, of the virtual channel description table, and
wherein an override location, which is corresponding to the virtual channel identified by the first service identifier, of the virtual channel description table overrides the second element, when the virtual channel map table includes the override location.
2. The method of claim 1, wherein the third element is virtual channel active times element.
3. The method of claim 1, wherein the master SI table further includes version information of the virtual channel map table.
4. An internet protocol television (IPTV) receiver of controlling virtual channel for building a channel map, comprising:
an IP network stack for receiving an IP stream including service information (SI) data and electronic program guide (EPG) data;
a file handler for demultiplexing the SI data and EPG data in the received IP stream;
a SI handler for demultiplexing a master SI table, a virtual channel map table including a first service identifier for identifying a virtual channel, and a virtual channel description table in the demultiplexed SI data, wherein the virtual channel description table includes a second service identifier and an element indicating designation of times when a virtual channel identified by the virtual channel service identifier is active, wherein the element includes at least one of start time and end time;
a SI decoder for parsing the element from the demultiplexed virtual channel description table; and
a controller for determining whether the element is omitted in the virtual channel description table, for determining the virtual channel identified by the second service identifier is always active, if the element is omitted in the virtual channel description table and for determining whether the virtual channel service identified by the second service identifier is inactive or active from the parsed element, if the element is not omitted in the virtual channel description table and for controlling display of the virtual channel according to the parsed element,
wherein details information of the virtual channel identified by the first service identifier corresponds to details information thats second service identifier is equal to the first service identifier,
wherein the second element is a default location, which is corresponding to every virtual channel in the channel map table, of the virtual channel description table, and
wherein an override location, which is corresponding to the virtual channel identified by the first service identifier, of the virtual channel description table overrides the second element, when the virtual channel map table includes the override location.
5. The IPTV receiver of claim 4, further comprises a storage unit for storing the demultiplexed master SI table, virtual channel map table, and virtual channel description table.
6. The IPTV receiver of claim 5, further comprises a display unit for displaying the virtual channel service.
7. The IPTV receiver of claim 4, wherein the controller controls the display unit to display the virtual channel.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A fixture for mounting a head window to a frame for use within a periscope system, said fixture comprising:
a baseplate wherein said baseplate includes at least three sections recessed from a face of said baseplate;
a clamping plate defining an aperture and including a recessed portion outside of said aperture wherein said recessed portion comprises an oval-shape shaped for the head window, said recessed portion being formed on one side of said clamping plate opposite the face of said baseplate and said recessed portion having a inner perimeter as an inner edge of the oval shape and an outer perimeter as an outer edge of the oval shape, with said clamping plate including a plurality of feet extending from said outer perimeter into said aperture with each of said feet including a groove having said outer perimeter of said recessed portion as an outer edge of said groove and said inner perimeter of said recessed portion as an inner edge of said groove;
a plurality of guide members capable of constraining relative movement of said clamping plate with respect to said baseplate for movement toward and away from said baseplate; and
at least three dial indicator gages secured to said clamping plate with a sensing end of each of said gages extending to each said recessed section of said baseplate with said gages operable for measurement of said relative movement between said clamping plate and said baseplate;
wherein the head window is capable of access through said aperture;
wherein said feet are capable of resting on the head window when the head window is in place and wherein said feet are capable of bonding the head window to said clamping plate.
2. The fixture of claim 1 comprising a plurality of springs mounted between said clamping plate and said baseplate.
3. The fixture of claim 2 comprising a plurality of threaded members protruding perpendicularly from said baseplate and corresponding threaded compression adjustment members, each of said plurality of springs being mounted over each of said plurality of threaded members wherein said springs are capable of forcing said clamping plate upward to allow removal of the head window from said fixture.