Paging and time keeping system with transmission of time slot identification used for synchronization

• US 5,168,271 A
• Filed: 08/17/1990
• Issued: 12/01/1992
• Est. Priority Date: 11/27/1985
• Status: Expired due to Term

• Current Assignee: Protocol-ip.com, LLC, Seiko Instruments Incorporated (Seiko Group)
• Original Assignee: Seiko Corporation (Seiko Group), Seiko Epson Corporation (Seiko Group)
• Inventors: Hoff, Don G.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): ZIMMERMAN, BRIAN A
• Application Number:
  US07/568,932
• Time in Patent Office: 837 Days
• Field of Search: 340/825.44, 340/825.47, 340/825.48, 455/181, 455/343, 370/82, 370/83, 370/95.1, 379/60, 368/47
• US Class Current: 340/7.43
• CPC Class Codes: G04G 21/04 using radio waves radio-controlled time-pieces G04R
• CPC Class Codes: G04R 20/14 the radio signal being a telecommunication standard signal, e.g. GSM
• CPC Class Codes: G04R 20/20 the radio signal being an AM/FM standard signal, e.g. RDS
• CPC Class Codes: G04R 60/04 Antennas attached to or integrated in watch bracelets
• CPC Class Codes: G08B 3/1016 using wireless transmission calling systems using transmission by inductive loop H04B5/00
• CPC Class Codes: G08B 5/222 Personal calling arrangements or devices, i.e. paging systems selective calling systems and call receivers H04W84/00, H04W68/00
• CPC Class Codes: G08B 5/223 using wireless transmission
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 88/026 using digital address codes
• CPC Class Codes: H04W 88/185 Selective call encoders for paging networks, e.g. paging centre devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

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. The watch pager displays time, telephone numbers and icons representing common types of paging messages.

Claims

1. A time keeping and paging system for communicating time of day and paging information to a plurality of receivers, comprising

a plurality of transmitters, each of said transmitters operating at a different frequency,

a plurality of means, one associated with each transmitter, for transmitting successive frames of information, each of said frames having substantially the same duration and being divided into a plurality of time slots, each time slot having a time reference point, selected time slots having an associated time slot number corresponding to the time reference point thereof,

a plurality of multifrequency receivers for receiving said information, each of said receivers being associated with one of said selected time slots, each of said receivers having means for receiving information from any of said transmitters, each receiver only receiving information from one of said transmitters at any particular time,

the time slot number of said selected time slots being transmitted during the associated time slot,

means for normally maintaining each of said receivers in a low power state and for periodically activating each of said receivers for an activation interval to receive information transmitted during the associated time slot, the periodicity of said activation interval corresponding to the occurrence of said associated time slot, each activation interval having a time reference point corresponding to the initiation thereof,

means for tuning each receiver to a different frequency if a signal is not received on the frequency to which the receiver is tuned at a particular time,

means for interrogating the information received by a given receiver and for comparing the received time slot number with the time slot number associated with the given receiver, and

means in each receiver for changing the associated activation interval time reference point in response to comparison of the received time slot number with the time slot number associated with said receiver,

time display mean in each receiver for displaying the time of day, said time of day means being synchronized with said time reference point,

whereby a receiver can determine if it has been activated during its associated time slot and if not said receiver can calculate the amount of change needed in its activation interval time reference point to cause said receiver to be activated during its associated time slot, and if said receiver does not receive a signal on the frequency to which said receiver is tuned said receiver switches to a new frequency.

2. The combination recited in claim 1 wherein each receiver includes means for storing a list of frequencies and means for tuning to a different one of the frequencies on said list if a signal is not received on the frequency to which the receiver is tuned.