US006060996A Ulllted States Patent [19] [11] Patent Number: 6,060,996 Kaiser et al. [45] Date 0f Patent: *May 9, 2000 [54] PAGER BROADCAST SYSTEM [56] References Cited [75] Inventors: Gordon E. Kaiser, Balboa Island; Steven J. Davis, Hermosa Beach, both US' PATENT DOCUMENTS of Cahf' 5,206,855 4/1993 Schwendeman et a1. ....... .. 340/825.44 [73] AssigneeZ Cue Network Corporation Irvine 5,404,569 4/1995 Schwendeman et a1. ....... .. 340/825.44 Calif ’ ’ 5,440,298 8/1995 Kuramatsu ................... .. 340/825.44 5,535,430 7/1996 Aoki et a1. ........ .. 455/552 [*] Notice: This patent issued on a continued pros- 5,757,782 5/1998 Gaskill .................................. .. 370/313 ecution application ?led under 37 CFR 1.53(d), and is subject to the tWenty year patent term provisions of 35 U_S_C_ Primary Examiner—HoWard L. Williams 154(a)(2). Assistant Examiner—Jean B. Jeanglaude Attorney, Agent, or Firm—ToWnsend and ToWnsend and [21] Appl. No.: 08/931,450 CreW LLP [22] Filed: Sep. 17, 1997 [57] ABSTRACT _ _Related_ Ufs‘ Application Data Paging network distributes a paging messages through a [60] Provisional application No. 60/037,828, Feb. 5, 1997. satellite. uplink. and a loW poWer satellite. transceiver. WhlCh. [51] Int. Cl.7 ..................................................... .. G08B 5/22 receives a Satellite Signal and rebroadcasts it at low power to [52] US. Cl. ....................................................... .. 340/825.44 nearby pages The pagers are adapted to detect the low [58] Field of Search ................................ .. 455/384, 38.2, poWer retransmissions and to sWitch to PM broadcast band 455/381, 62.1, 12.1, 13.2, 552, 126, 127, transmissions if the loW poWer transmission is not detected. 575, 370/373, 314, 329, 343, 340/82544, 825.47, 825.48, 825.49, 825.52; 342/35707, 386, 457 11 Claims, 8 Drawing Sheets l00\ I VOILE PAGES [m2 * rlzo PHONE PAGES cuEsAT /* CUE SATELLITE ALPHA 7' TERMINAL HUB COMMANDSMAP mm/ r ‘04 FM PAGES FoRwARnEo FROM DISTRIBUTION RADIO OTHER NETWORKS SYSTEM STATION U.S. Patent May 9, 2000 Sheet 1 0f 8 6,060,996 93: 29.25 k E 555 N01 ZQSEEmE / \ \9222 E 2%:2; \Q:<5: 85.228 :2:524252mum: 82oz:51.6 U.S. Patent May 9, 2000 Sheet 3 0f 8 6,060,996 2935352 2X335 z?wwwma5%532:F1 k -5:525: 9?52%“550: EaAo?msama :21% 5:5;E5225: a?55s a:35287 NOm\fwom.203.EEw (E522;saw:5:3: migi,as HV$555 AHanE552553 E225: UP‘.m, ExHV5%2 New ESE$52: an$255E22852:M22; Q“?llowwsmM22; llétezo555 52IIOQEEZ“3mm: 105%652% a;ais U.S. Patent May 9, 2000 Sheet 5 0f 8 6,060,996 Q81 <2 MOSEEE .2 3..5:5? a; EE2:$522 223:82E 2%:2FlE: 223 a0%Not Ni. ?52655::E82nU J“ _ _ 6:20 iswt6 U.S. Patent May 9, 2000 Sheet 6 0f 8 6,060,996 J5 22% 2H; 5% N21o5Naaw\\ 8Kon.E1NE\ o8 \ @2522.2:5:225 52mm:2 mmbtzwz?t.ask-Soc:ma: #42255.uEmzzz GD‘.m 52:55> 52mm:2 wow "2: mowzum U.S. Patent May 9, 2000 Sheet 7 0f 8 6,060,996 @S. LISTEN FOR 87.5 NHZ CARRIER [S4 SCAN FOR SWIFT SUBCARRIER LOOK ONTO 87.5 IN 88408 MHZ CARRIER AND BAND LISTEN FOR PAGES YES {86 SWIFLTOIONBONNNRIER oormuus AND LISTEN FOR -1 PAGES POLLING ,slo r57 LOCK ONTO CHECK FOR mas SUBCARRIER 31.5 CARRIER AND LISTEN FOR PAGES N0 53 ,3" CHECK FOR 87.5 CARRIER U.S. Patent May 9, 2000 Sheet 8 0f 8 6,060,996 FIG: 8 6,060,996 1 2 PAGER BROADCAST SYSTEM BRIEF DESCRIPTION OF THE DRAWINGS CROSS REFERENCE TO RELATED FIG. 1 is a block diagram of a paging netWork according APPLICATIONS to the present invention. This application claims priority of US. Provisional Appli FIG. 2 is a block diagram shoWing the satellite hub of cation Ser. No. 60/037,828 ?led Feb. 5, 1997, Which is FIG. 1 in greater detail. incorporated herein by reference for all purposes. FIG. 3 is a block diagram shoWing the mobile transceiver of FIG. 1 in greater detail. BACKGROUND OF THE INVENTION FIG. 4 is a block diagram shoWing the pager of FIG. 1 in The present invention relates to paging netWorks. In 10 greater detail. particular, one embodiment of the present invention pro FIG. 5 is a block diagram of a pager card as might be used vides an improved paging netWork Which uses satellites to in a personal computer to receive pages. ?ll gaps in FM station coverage. FIG. 6 is a block diagram of a page server operable over Paging netWorks generally operate by broadcasting small the MBS and SWIFT protocols. packets of data Which are addressed to speci?c pagers. A 15 FIG. 7 is a How chart of a process for seeking an optimal pager listens to the broadcasts and responds to those packets reception mode in a pager. addressed to that pager. FIG. 8 is an illustration of pagers in use inside a mobile One Way to broadcast messages is to use subcarriers of transceiver range and outside the mobile transceiver range. eXisting radio stations. This avoids the need for the operator of a paging netWork to purchase and maintain separate DESCRIPTION OF THE PREFERRED broadcast equipment. A standard FM radio station broad EMBODIMENT casts up to ?ve subchannels on subcarriers of 0 KhZ, 19 KhZ, 38 KhZ, 57 KhZ and 68 KhZ. The ?rst tWo subcarriers are In the preferred embodiment, a paging netWork subscriber used for mono and stereo transmission, respectively, of the is provided With a pager. A mobile paging transceiver is radio station broadcast picked up by ordinary radio receiv 25 provided either to the subscriber or a group of subscribers ers. The other three subcarriers are knoWn as SCA likely to be located near the mobile paging transceiver When (Secondary Channel Authority) subcarriers, and can be used a page is received. A typical transceiver is adapted to be to carry audio or data transmissions for receipt by specially mounted in a vehicle and the pagers of subscribers Who use con?gured receivers. Where a paging netWork broadcasts the vehicle are associated With that particular transceiver. using the SCA subcarriers of the radio station, the pagers are The pager listens for a loW-poWer signal from the trans con?gured to listen to a particular subcarrier band and ceiver. If the pager is out of range and cannot pick up the decode data thereon, looking for messages With that pager’s signal, it listens for a paging signal on an FM broadcast address. Many thousands of such pagers are in use today and channel. Since the transceiver broadcasts as loW poWer, it therefore can be made inexpensively. Another simpli?cation broadcasts just outside the FM broadcast band to avoid in the pager market has been the standardiZation of 35 being sWamped by a broadcasting FM station. Because the protocols, so that most pagers made today for SCA use have transceiver frequency is just outside the FM broadcast band, been standardiZed. conventional FM circuitry can be used, albeit With a local Because it is dif?cult to cover a large geographic region, oscillator capable of tuning just beyond the FM broadcast band. such as the North America continent, With continuous radio 40 coverage, a paging netWork might have gaps in coverage. If In a speci?c embodiment, the transceiver transmits on a pager is in an uncovered area, it Will not receive messages 87.5 MHZ to avoid FM broadcasts in the 88—108 MHZ band. sent to it. Since pagers are generally receive-only, the paging If the pager is out of range of the transceiver, it scans the FM netWork does not have a Way to ensure that the pager broadcast band to ?nd a station signal having a subscarrier received a message, therefore it is incumbent on the paging 45 broadcasting pages using the SWIFT protocol. If a SWIFT netWork to make efforts to ensure coverage. protocol subcarrier is not found, the pager scans for an MBS Of course, pagers Would be more likely to receive signals protocol subcarrier. Periodically, the pager Will look for the if they have better antennae, higher poWer, etc. 87.5 MHZ carrier or the SWIFT subcarrier. In North Unfortunately, longer range pagers are often unsuitable for America, and possibly other geographic areas, SWIFT refers applications Where the user of the pager Wants a compact, to an 8000 bps data channel modulated on the 76 kHZ light device to carry around. subcarrier of a cooperating radio station’s signal, Which Therefore, What is needed is a system for increasing pager MBS refers to an 1187.5 bps data channel modulated on the reception Without adding to the bulk of a pager. Preferably, 57 kHZ subcarrier of a cooperating radio station’s signal. the increase must be done Without modifying the design of Referring noW to FIG. 1, a block diagram of an overall the basic, standardiZed pager. 55 paging system 100 is there shoWn. For simplicity, the details of conventional FM signal distribution are omitted and only SUMMARY OF THE INVENTION one FM radio station, one transceiver and one pager are An improved paging netWork is provided by virtue of the shoWn. In practice, hoWever, several FM radio stations present invention. In one embodiment, a page service sends Would be broadcasting pages (or other conventional non-FM pages to a satellite, Which broadcasts them to satellite 60 broadcast methods might be used) and many transceivers transceivers, some of Which are mounted in vehicles. The and pagers Would be in use.