초록 ▼

A manhole security cover includes a manhole cover body comprising a non-metallic RF signal transmissive material. The manhole cover body is seatable on a manhole frame to cover a manhole opening. In the seated position, the first side is accessible from outside the manhole, the second side is dispos

A manhole security cover includes a manhole cover body comprising a non-metallic RF signal transmissive material. The manhole cover body is seatable on a manhole frame to cover a manhole opening. In the seated position, the first side is accessible from outside the manhole, the second side is disposed within the manhole, and the peripheral edge portion engages a manhole cover support surface on the manhole frame. A manhole cover tamper sensor is responsive to a predetermined movement of the manhole security cover body. A transmitter is operatively connected to the manhole cover tamper sensor and configured to generate a radio frequency manhole cover tamper signal when the manhole cover tamper sensor detects the predetermined movement of the manhole security cover body. An antenna is operatively coupled to the transmitter to radiate radio frequency energy through the manhole cover body to a receiver located outside of said manhole.

대표청구항 ▼

1. A manhole security cover for covering an opening to a manhole, comprising: a manhole cover body comprising a non-metallic RF signal transmissive material;said manhole cover body having a generally planar first side, a second side spaced from said first side and a peripheral edge portion;said manh

1. A manhole security cover for covering an opening to a manhole, comprising: a manhole cover body comprising a non-metallic RF signal transmissive material;said manhole cover body having a generally planar first side, a second side spaced from said first side and a peripheral edge portion;said manhole cover body being operatively positionable during use thereof to seat on a manhole frame and cover said manhole opening, such that said first side of said manhole cover body is accessible from outside said manhole, said second side of said manhole cover body is disposed within said manhole, and said peripheral edge portion of said manhole cover body engages a manhole cover support surface on said manhole frame;a manhole cover tamper sensor responsive to a predetermined movement of said manhole security cover body;a transmitter operatively connected to said manhole cover tamper sensor and configured to generate a radio frequency manhole cover tamper signal when said manhole cover tamper sensor detects said predetermined movement of said manhole security cover body;an antenna operatively coupled to said transmitter to radiate radio frequency energy through said manhole cover body to a receiver located outside of said manhole; andsaid transmitter, said antenna and said tamper sensor being enclosed within a single transmitter/antenna/sensor (TAS) unit on said second side of said manhole cover body. 2. The manhole security cover of claim 1, wherein said TAS unit comprises a TAS housing having a TAS base and a TAS cover. 3. The manhole security cover of claim 1, wherein said tamper sensor comprises technology selected from the group consisting of electronic movement technology and electronic positioning technology. 4. The manhole security cover of claim 3, wherein said electronic movement technology is selected from the group consisting of inertial sensors, tilt sensors, proximity sensors, and/or vibration sensors. 5. The manhole security cover of claim 3, wherein said electronic positioning technology is selected from the group consisting of GPS devices. 6. The manhole security cover of claim 1, wherein said TAS unit comprises sensor control logic for distinguishing between actual manhole cover tamper events and non-tamper-related events. 7. The manhole security cover of claim 6, wherein said sensor control logic comprises programming, circuitry, and/or mechanical control elements to adjust a sensitivity of said tamper sensor and/or set its detection thresholds. 8. The manhole security cover of claim 7, wherein said sensor control logic is operable to establish a home position following installation of the manhole security cover on a manhole frame. 9. The manhole security cover of claim 8, wherein sensor control logic comprises an auto-leveling feature for establishing said home position when said manhole security cover is installed at a non-horizontal grade angle. 10. The manhole security cover of claim 8, wherein said sensor control logic is operable to detect said manhole security cover being moved a threshold distance from said home position, said sensor control logic utilizing one or more threshold distances to monitor translation in one or more directions, rotation in one or more directions, or both. 11. The manhole security cover of claim 10, wherein said sensor control logic utilizes a threshold distance for vertical movement of said manhole security cover that is equal to a thickness of said manhole cover body, such that an alarm may be generated if an unauthorized attempt is made to lift said manhole security cover enough so that a harmful instrumentality or agent could be dropped into said manhole opening. 12. The manhole security cover of claim 8, wherein sensor control logic is operable to provide an auto-leveling feature for establishing said home position when said manhole security cover is installed at a non-horizontal grade angle. 13. The manhole security cover of claim 1, further including: a key-actuated latch mechanism operable to engage and lock said manhole cover body to said manhole frame, said latch mechanism comprising one or more retractable latches on said second side of said manhole cover body and a latch drive unit, said latch drive unit being operatively coupled to said latches and accessible on said first side of said manhole cover body for engagement by a security key; andsaid TAS unit being mounted on a non-moving part of said latch mechanism at a location that is spaced from said second side of said manhole cover body in order to reduce false alarms caused by deflection of said manhole cover body. 14. The manhole security cover of claim 12, wherein said tamper sensor comprises a cover deflection sensor operable to sense cover deflections. 15. The manhole security cover of claim 14, wherein said cover deflection sensor comprises a linear sensing device that maintains contact with said manhole cover body. 16. The manhole security cover of claim 15, wherein said tamper sensor comprises a latch mechanism sensor operable to sense latch mechanism movement. 17. The manhole security cover of claim 16, wherein said transmitter is configured to generate a manhole cover latching signal when said latch mechanism sensor senses said latch mechanism being latched or unlatched, said TAS unit supporting a two-stage alert wherein receipt of an unlatching signal within a predetermined time period prior to receipt of a tamper signal enables a determination of whether removal of said manhole security cover from said manhole opening is authorized or unauthorized.