Paging system with energy efficient station location

• US 5,266,945 A
• Filed: 01/15/1991
• Issued: 11/30/1993
• 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: Peek, William H., Gaskill, Garold B.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): Magistre, Dervis
• Application Number:
  US07/642,131
• Time in Patent Office: 1,050 Days
• Field of Search: 340/825.04, 340/825.44, 340/825.13, 340/825.47, 340/825.48, 340/311.1, 340/825.49, 455/161, 455/166, 455/185, 455/186, 455/31, 455/32, 379/57, 379/63
• US Class Current: 340/7.33
• CPC Class Codes: G04G 21/04 using radio waves radio-controlled time-pieces G04R
• CPC Class Codes: H04B 1/088 with parts of the receiver detachable or collapsible
• CPC Class Codes: H04B 1/1615 Switching on; Switching off, e.g. remotely battery saving circuits associated with selective call operation H04W52/00; details of power consumption reduction in a PLL, H03L7/0802, H03L7/14, H03L2207/08, H03L2207/18; muting amplifiers by gain control see H03G3/34
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: H04W 52/0287 changing the clock frequency of a controller in the equipment
• 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 method for searching for a station carrying paging data without unduly draining the paging receiver battery. If a station to which the receiver is presently tuned becomes unreliable, the pager scans among channels listed in a local channel list. If no paging data is received on these channels, the scanning among the local list channels may optionally proceed for a further interval at a slower rate. After it appears that paging data will not be found on channels listed in the local list, the pager begins a full spectrum search at a slow rate until it again finds a channel carrying paging data. By this arrangement, battery power is expended at a rate roughly in accordance with the likelihood of finding a paging station.

Claims

1. In a battery operated radio pager receiver which can receive signals on a plurality of different frequencies in a frequency spectrum, said receiver only requiring activation for a very short period of time in order to determine if a paging signal is present at a particular frequency, the amount of power expended by said receiver during a particular period of time being dependent upon the number of frequencies sampled during said period of time, the combination of,

fast sweep means operable when said receiver is first activated for conducting a fast spectrum wide frequency sweep to locate a first frequency with a paging signal,

regular cycle means operable when said first frequency is located for initially receiving a first list of frequencies which have paging signals broadcast thereon,

means for periodically receiving paging signals on said first frequency,

local list fast scanning means operable when a signal is not received on said first frequency after initially receiving said first list, for scanning at a fast scanning rate through all the frequencies on said first list to locate a frequency with a paging signal, and for activating said regular cycle means when a signal is located,

local list slow scan means operable when a paging signal is not located by said local list fast scanning means for scanning for a first period of time at a slow scanning rate through all the frequencies on said first list to locate a frequency,

means activating said regular cycle means when said local list slow scan finds a frequency with a paging signal, and

means operable when said local list slow scan means does not find a frequency with a paging signal for searching through all frequencies in said spectrum at a very slow rate until a frequency with a paging signal is located,

whereby said battery life is extended by using a combination of slow and fast frequency scanning and frequency sweeping.

2. In a battery operated radio paging device, the method of searching in a frequency spectrum for a radio frequency carrying a pager signal without unduly draining said battery, said pager including a local list of radio frequencies on which signals are being broadcast comprising the steps of,

scanning through the frequencies on said local list at a first speed which is a relatively high rate of speed to locate a frequency with a paging signal,

when no frequency with a paging signal is found within a first period, reducing the rate of speed at which said scanning proceeds to a second speed, and continuing to scan through said local list local list for a second period of time, and

when no frequency is found with a paging signal searching through said entire spectrum of frequencies at a third speed which is a slow rate to find a frequency which has a paging signal and a new local list of radio frequencies,

whereby the rate of expenditure of battery energy is reduced by using a plurality of scanning speeds under different conditions.

3. A method of operating a radio pager in a system where the same message is broadcast on a plurality of frequencies, comprising the steps:

providing the pager with a local list of paging frequencies on which said message is broadcast;

periodically changing frequencies to another frequency on said list listening for a paging signal of said frequencies;

when a paging signal is not reliably received on a frequency, then scanning among the frequencies on said local list to find a paging signal, said scanning occurring at a first rate which is faster rate than the periodic changing frequencies rate;

when the scanning is unable to locate a paging signal within a predetermined interval of time, then slow scanning among the frequencies on the local list to find a paging signal, said slow scanning checking occurring at a slower rate than the said scanning rate; and

when said slow scanning is unable to locate a paging signal within a predetermined interval, then searching among a larger list of frequencies to find a paging signal, said searching occurring at a rate slower than said first rate.