1. A method for detecting glass breakage, said method comprising:
acquiring thermal images of a monitored area including a glass portion;
generating a reference image from a thermal image of said monitored area;
comparing subsequently acquired thermal images against said reference image; and
generating a glass breakage alert when said comparison indicates a change in thermal signature with respect to said reference image,
wherein said compared thermal image is determined as unchanged with respect to said reference image if differences between said thermal image and said reference image are within a predefined threshold, and determined as changed if differences between said thermal image and said reference image exceed said predefined threshold.
2. The method as in claim 1, wherein said reference image provides a baseline thermal signature of said monitored area when said glass portion is present.
3. The method as in claim 1, wherein a new reference image is generated at predefined intervals, said new reference image replacing a previous reference image.
4. The method as in claim 1, wherein said glass breakage alert is generated only after acquiring thermal images determined to be changed over a preset interval of time, and not issuing a glass breakage alert if a thermal image is acquired within said preset interval of time that is to be determined unchanged with respect to said reference image.
5. A method for detecting glass breakage, said method comprising:
acquiring thermal images of a monitored area including a glass portion;
generating a reference image from a thermal image of said monitored area;
comparing subsequently acquired thermal images against said reference image; and
generating a glass breakage alert when said comparison indicates a change in thermal signature with respect to said reference image,
wherein said glass breakage alert is generated only after acquiring thermal images determined to be changed over a preset interval of time, and not issuing a glass breakage alert if a thermal image is acquired within said preset interval of time that is to be determined unchanged with respect to said reference image.
6. The method as in claim 5, wherein said reference image provides a baseline thermal signature of said monitored area when said glass portion is present.
7. The method as in claim 5, wherein a new reference image is generated at predefined intervals, said new reference image replacing a previous reference image.
8. The method as in claim 5, wherein said compared thermal image is determined as unchanged with respect to said reference image if differences between said thermal image and said reference image are within a predefined threshold, and determined as changed if differences between said thermal image and said reference image exceed said predefined threshold.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What we claim is:
1. A switch supporting a multiple spanning tree protocol comprising:
a table including a default spanning tree in a multiple spanning tree;
a transceiver for transmitting, upon receipt of a frame having an individual destination address from a terminal side, an inquiry frame to a destination terminal of the individual destination address through the default spanning tree, and for transmitting inquiry response frames to all of the spanning trees in the multiple spanning tree if the destination terminal is connected to the switch; and
an optimum route selecting processor for selecting an optimum spanning tree based on information in the inquiry response frames from all of the spanning trees.
2. The switch as claimed in claim 1 wherein the optimum route selecting processor determines the optimum spanning tree by a hop count.
3. The switch as claimed in claim 1 wherein the optimum route selecting processor determines the optimum spanning tree by a path cost.
4. The switch as claimed in claim 1 wherein a packet used for the spanning trees is utilized as the inquiry frame.
5. The switch as claimed in claim 1 or 4 wherein the optimum route selecting processor transmits the inquiry frame and the inquiry response frame, upon receipt thereof to the default spanning tree if the destination terminal is not connected to the switch.
6. The switch as claimed in claim 1 wherein the optimum route selecting processor prepares a temporary spanning tree table based on the inquiry response frames received from all of the spanning trees, and selects the optimum spanning tree referring to the table.
7. A bridged network comprising:
a plurality of switches respectively supporting a multiple spanning tree protocol for a multiple spanning tree including a default spanning tree;
the switches including a first and a second switch,
the first switch having received a frame with an individual destination address from a terminal side transmitting an inquiry frame to a destination terminal at the individual address through the default spanning tree,
the second switch having received the inquiry frame transmitting inquiry response frames to all of the spanning trees in the multiple spanning tree if the destination terminal is connected thereto, and
the first switch having received the inquiry response frames from all of the spanning trees selecting an optimum spanning tree based on information in the inquiry response frame.
8. The bridged network as claimed in claim 7 wherein the first switch determines the optimum spanning tree by a hop count.
9. The bridged network as claimed in claim 7 wherein the first switch determines the optimum spanning tree by a path cost.
10. The bridged network as claimed in claim 7 wherein the first switch utilizes a packet used for the spanning trees as the inquiry frame.
11. The bridged network as claimed in claim 7 or 10 wherein the switches transmit the inquiry frame and the inquiry response frame, upon receipt thereof to the default spanning tree if the destination terminal is not connected to the switches.
12. The bridged network as claimed in claim 7 wherein the first switch prepares a temporary spanning tree table based on the inquiry response frames received from all of the spanning trees, and selects the optimum spanning tree referring to the table.