Paging and time keeping system with transmission of time slot identification used for synchronization
US5168271A · kind A · utility
Assignees
Inventor
Key dates
| Filing date | Aug 17, 1990 |
| Grant date | Dec 1, 1992 |
| Priority date | — |
| Expiry date | Aug 17, 2010 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02D30/70
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A wide area paging system is disclosed in which paging messages input to the system in one local area can be broadcast to a receiver in any other local area without necessarily broadcasting the message in all areas. A local area clearinghouse in each area stores resident subscriber data including current location and receiver serial number. This data is used to transfer messages over a data network to the correct clearinghouse. The system uses a TDM data protocol. The data is encoded and transmitted at a very high rate (e.g., 19,000 baud) in short packets (256 bits/13 milliseconds) via stereo FM sidebands. Receivers are assigned to receive sequentially numbered time slots matching a portion of their address. The addresses of intended receivers are included in the data packets. Battery-powered receivers are deactivated between packets and reactivated in accordance with the sequential time slot number scheme to receive an incoming packet. Messages longer than a packet are segmented and transmitted in two or more packets, linked together by data contained in the packets. A watch pager used in the system employs a wristband antenna which electromagnetically couples to the user's body. …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.