WO1991007064A1 - Recepteur a balayage avec depassement manuel de routines de balayage de frequences - Google Patents

Recepteur a balayage avec depassement manuel de routines de balayage de frequences Download PDF

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Publication number
WO1991007064A1
WO1991007064A1 PCT/US1990/005264 US9005264W WO9107064A1 WO 1991007064 A1 WO1991007064 A1 WO 1991007064A1 US 9005264 W US9005264 W US 9005264W WO 9107064 A1 WO9107064 A1 WO 9107064A1
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WO
WIPO (PCT)
Prior art keywords
channels
receiver
data
protocol
channel
Prior art date
Application number
PCT/US1990/005264
Other languages
English (en)
Inventor
Garold B. Gaskill
Daniel J. Park
Original Assignee
At&E Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by At&E Corporation filed Critical At&E Corporation
Publication of WO1991007064A1 publication Critical patent/WO1991007064A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W8/00—Network data management
    • H04W8/22—Processing or transfer of terminal data, e.g. status or physical capabilities
    • H04W8/24—Transfer of terminal data
    • H04W8/245—Transfer of terminal data from a network towards a terminal
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J1/00—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general
    • H03J1/0008—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general using a central processing unit, e.g. a microprocessor
    • H03J1/0091—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general using a central processing unit, e.g. a microprocessor provided with means for scanning over a band of frequencies
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/02—Terminal devices
    • H04W88/022—Selective call receivers

Definitions

  • Receivers sometimes include the capability to tune through a number of channels to locate one carrying desired signals.
  • the receiver simply tunes every channel in the spectrum until a channel carrying the desired signals is found.
  • each transmitter broadcasts a list of alternative channels that are used in the area surrounding the transmitter. On finding one such station, the receiver is provided a small local list of other stations that it can examine for data if the original station is lost, obviating the need to tune through the entire frequency spectrum. This checking process is energy intensive and reduces the battery life available for the more productive task of receiving pages.
  • the pager may exhaust its battery vainly searching for paging signals where there are none. Accordingly, in the system disclosed in the above-referenced applications, after failing to find a paging signal on the channels included on its local list for a predetermined period (37.5 minutes in the illustrated embodiment) , the receiver begins a full spectrum scan to find a new paging channel. When it finds a satisfactory paging channel, the pager receives a new local list identifying paging transmitters in that new locality.
  • a frequency agile data receiver searches as needed, according to a first protocol, among a plurality of channels to find a channel carrying data.
  • a control activated by the user interrupts this first protocol and institutes a second protocol different than the first.
  • the first protocol may search at a relatively slow rate among a limited group of previously identified channels.
  • the second protocol may scan rapidly through the universe of candidate channels.
  • a person who knowingly moves to a new locality e.g., flies to another city
  • Fig. 1 is a schematic block diagram illustrating a paging system that may use the present invention.
  • Fig. 2 is a schematic block diagram illustrating a wristwatch paging receiver used in the system of Fig. 1.
  • Fig. 3 is a block diagram illustrating the partial contents of a microprocessor memory used in the paging receiver of Fig. 2.
  • Fig. 4 is a flow chart illustrating operation of the paging system of Fig. l.
  • the present invention will be illustrated with reference to a paging system (the "Gaskill" system) described in U.S. Patent 4,713,808 and in allowed application Serial No. 07/352,635. However, it will be recognized that the invention is not so limited.
  • the Gaskill system includes clearinghouses 10, broadcasting facilities 12 and wristwatch paging receivers 14.
  • the clearinghouses 10 are fully automated centralized facilities which accept messages, validate customer identification, determine message destinations and route messages to the appropriate broadcast facilities for transmission. Callers to the system dial a local clearinghouse telephone number and hear voice prompts that guide them through a simple process for sending messages.
  • the broadcast facilities 12 are typically conventional FM broadcast stations that carry paging data on subcarriers of their signals. Multiple stations are used for transmission in a given area. Diversity of signals combined with repeated transmission insures the paging subscribers receive their messages with a high degree of reliability.
  • the wristwatch paging receivers 14 are worn by the customers and receive the paging messages broadcast by the broadcast facilities.
  • the receiver basically includes an antenna 16, a frequency agile receiver 18, a data demodulator 20, a protocol decoder 21, a microprocessor 22 (with associated memory 24) and a user interface 26.
  • Memory 24 contains various data and programs relating to operation of the watch, such as a subroutine for finding a new station, a subroutine for obtaining a local channel list, a datum indicative of the frequency to which the watch is presently tuned, and a local channel list.
  • Fig. 3 illustrates some of the contents of this memory 24.
  • antenna 16 receives radio frequency signals in the desired reception band (here 88 to 108 MHz) and couples them to the frequency agile receiver 18.
  • the frequency agile receiver 18 processes the RF signals from the antenna and produces baseband output signals corresponding to a desired FM station within the reception band — typically an FM signal carrying the paging data on an SCA subcarrier thereof.
  • This SCA paging data is detected by the data demodulator 20, decoded by the protocol decoder 21 and is provided to the microprocessor 22 for processing.
  • the microprocessor 22 drives the user interface 26 to alert the user of paging messages.
  • local channel lists are transmitted to the pagers and provide a list of alternative channels to which the pager can refer if the channel presently being received becomes unreliable. For background, it may be helpful to review the disclosures of these applications.
  • the paging signals received by the receiver 14 are formatted as sequences of packets.
  • the first three packets of each sequence are termed "control" packets.
  • the first of the control packets is termed the “control 0" packet and contains the date and time and the first entry of the channel list.
  • the second packet is termed the "control 1" packet and contains the other entries in the channel list.
  • the third packet is a spare.
  • These three control packets are followed by 1024 "data" packets in which the paging data is transmitted.
  • Subsequent sequences are similarly formatted.
  • a new sequence (or "subframe") of 1027 packets is transmitted every 14.0625 seconds.
  • a “search” is an operation in which the receiver sequentially checks a plurality of previously identified channels (i.e. channels that have been identified by a local channel list) for a desired signal.
  • a “scan,” in contrast, is an operation in which the receiver tunes through all possible channels looking for a desired signal, without regard to whether any has been previously identified.
  • a paging receiver When a paging receiver is newly-energized, it first begins a spectrum-wide scan for a station carrying the paging data. When such a station is found, the receiver decodes the first and second packets and stores the local channel list contained therein into microprocessor memory 24. Thereafter, the receiver continues to operate on the original channel until there is a failure in reception, such as receipt of a packet with uncorrectable errors.
  • the receiver searches among other channels in the local list until good data is again received.
  • This procedure is illustrated in Fig. 4.
  • the microprocessor 22 causes the frequency agile receiver 18 to begin a fast scan of the entire FM broadcast spectrum, 88.1 to 107.9 MHz in increments of 0.2 MHz, until a channel with paging data is located.
  • the receiver reads the local channel list transmitted in the control 0 and control 1 packets thereof and stores the list in memory 24. Thereafter, the receiver momentarily energizes once every 1.875 minutes to listen for paging messages directed to the receiver's user. As long as reception on this channel continues to be reliable, the receiver stays in this low energy mode of operation, simply listening periodically for paging messages.
  • the receiver 14 will detect the loss of paging data utilizing a CRC error.
  • This error prompts the microprocessor 22 to begin a search through the channels listed in the local channel list for an alternative source of paging signals.
  • the transmission on these channels are generally all time- staggered relative to one another, so the receiver can tune to the first alternative channel for a given frame of information and, if unsuccessful, can tune to the next alternative channel, and so forth, all within the frame period of 1.875 minutes.
  • this search continues for four complete cycles through the local channel list (i.e., a maximum period of 7.5 minutes) looking for paging data.
  • the receiver's loss of the original signal was caused by some transitory effect, such as a momentary incident of multipath while the user drove between buildings in a downtown area, the receiver quickly resumes reception of paging signals, generally without loss of a single frame of data since each channel transmits each frame in time-staggered relation. If, however, the receiver has not reacquired a paging signal within this 7.5 minute search time, the microprocessor presumes the signal loss is not of momentary duration and ceases the receiver's relatively high energy search operation.
  • the energization of the receiver seven times every 1.875 minutes during this operation consumes power at a rate of seven times that consumed during normal operation, in which the receiver is energized only once every 1.875 minutes.
  • the microprocessor may optionally continue its searching though the local channel list, but at a slower rate, such as one channel every 1.875 minutes. This operation consumes power at the same rate as the normal receiving mode of operation, yet concentrates the search among the channels most likely to be carrying paging signals. In the illustrated embodiment, this slower searching mode continues for 30 additional minutes.
  • the microprocessor then instructs the frequency agile receiver to institute a spectrum-wide scan for paging data.
  • This scan is desirably conducted at a relatively slow rate, such as one channel every 1.875 minutes, to conserve battery power.
  • the microprocessor can be programmed to begin this mode of operation with one fast scan through the spectrum, and thereafter continue the scan at the more relaxed pace. This low energy scan continues until a paging signal is finally found.
  • the receiver reduces battery drain by searching among the listed channels more slowly. If this limited search continues to prove unavailing, the receiver begins scanning the entire spectrum, but at a rate that consumes little battery energy. Thus, the battery energy is expended where it is most likely to do the most good, with a high energy search among the most likely channels and a progressively lower energy search or scan as the likelihood of quickly finding a station diminishes. While this arrangement greatly reduces battery drain when a pager is moved from one geographical area to another, a period (37.5 minutes) may nonetheless elapse during which the pager vainly searches its original (now stale) local channel list looking for paging stations where there are none.
  • the paging receiver 14 is provided with a button 30 (Figs. 1 and 2) that can be activated by the user to cause the receiver to interrupt its normal searching mode of operation and institute a scanning operation instead.
  • the receiver undertakes a sweep of the spectrum, according to a protocol different than that normally used, for a channel carrying paging data.
  • the normal protocol is considered to be the series of steps following the first failure to receive paging data in the block entitled "Is Reception Reliable?" in Fig. 4.
  • the receiver does not initially limit itself to the previously identified channels stored in the local channel list. Rather, it sweeps spectrum-wide.
  • the receiver On locating a channel carrying paging data, the receiver obtains a new local list identifying other channels carrying paging data in the receiver's locale.
  • the receiver can begin this fast-scan operation with a just single fast sweep through the spectrum and thereafter continue the spectrum-wide scanning at a slower rate.
  • a person who knowingly moves to a new locality e.g., flies to another city

Abstract

Un récepteur de données à variabilité en fréquences élevée, trie, selon un premier protocole, une pluralité de canaux pour retrouver un canal portant des données (B). Une commande (30) actionnée par l'utilisateur interrompt ce premier protocole (B) et introduit un deuxième protocole qui est différent du premier. Lorsque le premier protocole est utilisé pour un récepteur de téléappel (14) il peut accorder séquentiellement le récepteur sur une pluralité de canaux préalablement identifiés afin de retrouver un canal sur lequel des données de téléappel sont convenablement reçues (F). Le deuxième protocole peut s'accorder séquentiellement sur tous canaux possibles afin de retrouver un tel canal. Grâce à cette disposition, une personne qui passe dans une autre région (se déplace par avion à une autre ville) peut donner des instructions au récepteur de téléappel d'abandonner une liste de canaux candidats préalablement identifiés et de commencer un balayage spectral afin de retrouver de nouveaux canaux de téléappel satifaisants.
PCT/US1990/005264 1989-10-31 1990-09-17 Recepteur a balayage avec depassement manuel de routines de balayage de frequences WO1991007064A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43045789A 1989-10-31 1989-10-31
US430,457 1989-10-31

Publications (1)

Publication Number Publication Date
WO1991007064A1 true WO1991007064A1 (fr) 1991-05-16

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Country Status (2)

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AU (1) AU6546390A (fr)
WO (1) WO1991007064A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0529991A1 (fr) * 1991-08-23 1993-03-03 Nec Corporation Procédé de recherche de canal radio dans un système d'appel de personnes à canaux multiples
EP0593027A1 (fr) * 1992-10-14 1994-04-20 Nec Corporation Récepteur d'appel radio et procédé de recherche de canal radiofréquence

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3755782A (en) * 1972-08-28 1973-08-28 Ibm Communication system polling method
US4247908A (en) * 1978-12-08 1981-01-27 Motorola, Inc. Re-linked portable data terminal controller system
US4419765A (en) * 1979-10-12 1983-12-06 Keith H. Wycoff Signal absence detector
US4644347A (en) * 1983-08-10 1987-02-17 Motorola, Inc. Multiple frequency message system
US4710972A (en) * 1985-10-21 1987-12-01 Sony Corporation SHF receiver
US4750198A (en) * 1986-12-12 1988-06-07 Astronet Corporation/Plessey U.K. Cellular radiotelephone system providing diverse separately-accessible groups of channels

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3755782A (en) * 1972-08-28 1973-08-28 Ibm Communication system polling method
US4247908A (en) * 1978-12-08 1981-01-27 Motorola, Inc. Re-linked portable data terminal controller system
US4419765A (en) * 1979-10-12 1983-12-06 Keith H. Wycoff Signal absence detector
US4644347A (en) * 1983-08-10 1987-02-17 Motorola, Inc. Multiple frequency message system
US4710972A (en) * 1985-10-21 1987-12-01 Sony Corporation SHF receiver
US4750198A (en) * 1986-12-12 1988-06-07 Astronet Corporation/Plessey U.K. Cellular radiotelephone system providing diverse separately-accessible groups of channels

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0529991A1 (fr) * 1991-08-23 1993-03-03 Nec Corporation Procédé de recherche de canal radio dans un système d'appel de personnes à canaux multiples
US5565859A (en) * 1991-08-23 1996-10-15 Nec Corporation Method of detecting a paging channel in a multi-frequency radio pager network
EP0593027A1 (fr) * 1992-10-14 1994-04-20 Nec Corporation Récepteur d'appel radio et procédé de recherche de canal radiofréquence
AU676202B2 (en) * 1992-10-14 1997-03-06 Nec Corporation Paging receiver and radio frequency channel searching method for the same

Also Published As

Publication number Publication date
AU6546390A (en) 1991-05-31

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