Note: Descriptions are shown in the official language in which they were submitted.
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DUAL CHANNEL FM RECEIVER WITH ON DEMAND INFORMATION SERVICES
RELATED APPLICATIONS
The present application is a continuation-in-part of U.S. Patent Application
Number 08/365,859 filed December 29, 1994 naming inventors John Richartz and
Dimitri Dimitriadis and entitled TRANSMITTING AND DISPLAYING ON A
RECEIVER INFORMATION DESCRIBING BROADCAST PROGRAMS; and a
continuation-in-part of U.S. Patent Application Serial Number 08/366,208 filed
December 29, 1994 naming inventors John Richartz and Dimitri Dimitriadis and
entitled SYSTEM FOR IDENTIFYING AND RESPONDING TO DIFFERENT
BROADCAST PROGRAMS. Both of the above U.S. Patent Applications are
assigned in common to the Assignee of the present application.
FIELD OF THE INVENTION
The present invention relates generally to communication systems, and
particularly to delivery of information services on demand to a remote personal
information terminal.
BACKGROUND OF THE INVENTION
Commercial FM (frequency modulation) radio stations can simultaneously
transmit both a main audio signal and a subcarrier signal. The main audio signal
carries the traditional voice and music presentation and the subcarrier signal can
carry for example a data signal for a paging system. Normal FM radios receive the
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main signal and paging devices such as the devices shown in U.S. Patent Number
4,713,808 entitled WATCH PAGER SYSTEM AND COMMUNICATION PROTOCOL
and issued December 15, 1987, receive paging messages transmitted on the
subcarrier.
Information service delivery to users of personal information terminals can
take a variety of forms. One type of information delivery system is by radio signal
broadcast to remote radio signal receiving devices. The communication link is a
one-way link, there being no radio signal transmission capability in the remote
personal information terminal.
Information service delivery has been incorporated into existing paging
systems. Users of the paging system devices subscribe to inro""alion services as
represented in a subscription arrangement previously established and maintained
by the paging system. Such inror",~lion subscription arrangements are established
by the paging system operator causing certain information service paging messages
to be directed to a given paging device.
A user so",eLi",es wants to only obtain a certain information service item
once or a limited number of times when needed. For example, when a travelling
user of a receiving device leaves a "home" region or city and goes to another area.
While in the distant area and away from home, the user has different information
service requirements. Furthermore, signal transmission in the distant area does not
correspond to signal transmission in the home region, i.e., a different frequency or
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set of frequencies carry information addressed to receiving devices normally located
in that distant area. To obtain information services while away from home, the user
could conlacl the paging system operator to direct certain information services to its
terminal while in the distant region. Upon leaving the distant region, however, the
user must again contact the paging system to modify its subscription.
Incorporating information services into a paging system can consume a
significant portion of the system bandwidth. For example, some information services
require transmission of a significant volume of data, e.g., stock information. In some
multiple-frequency paging systems, i.e., systems employing a plurality of
transmission facilities to provide paging messages to frequency-agile receivers, all
i, Iror"~alion services are provided on all transmission frequencies. Redundancy in
paging system transmission better ensures reception of vital information, i.e., paging
information, by paging devices. Since some information services consume
significant information delivery bandwidth. It is not feasible to incorporate a broad
spectrum of i"ro""~lion services into a paging system.
Accordingly, it would be desirable to provide in a one-way communication
system, e.g., in a paging system, an ability to provide on demand inr.,r"~alion
services without requiring the user to inleracl with the paging system by way of an
alternate channel of communication, e.g., by telephoning the paging system to
modify i, Iror,~l~lion service paging messages directed thereto. The user would like
to access on a limited basis, i.e., one or several times, information service items
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without inconvenience and without establishing an information service subscription
through interaction with the paging system.
The subject matter of the present invention provides information services on
demand by user whereby the user need not interact directly by alternate
communication channel with the paging system to receive selected information
service items on a limited basis.
SUMMARY OF THE INVENTION
The present invention provides in an information delivery system a receiver
receiving both a main FM station audio transmission and a subcarrier transmission.
In addition to normal paging messages, the receiver receives information services
on user demand by way of the subcarrier signal. The user selectively receives one
or both of an audio signal ard paging system data including information services on
demand.
A method of information service delivery under the present invention includes
reception of a set of i"ror",dlion service items in a plurality of inrc,r",alion categories.
A first subset of inror",dlion service items are broadcast in a first transmission
channel and a second subset of information service items are broadcast in a second
transmission channel. Each transmission channel providing information service
items also includes indicia of information category found therein. Remote
information terminals respond to a user demand for a given information category by
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seeking indicia corresponding to the demanded inrorlllalion category in at least one
of the first and second transmission channels.
A system delivering inror",aLion services to remote information terminals
under the present invention includes a radio signal transmission portion providing
data transmission across a plurality of l,~"sr"ission channels. A l,d"s",ission
control portion receives inrurmalion items in a plurality of information service
categories and broadcasts such information items by way of the radio signal
l,~"smission portion in at least two of the transmission channels. Each radio signal
l,d"sr"ission includes indicia therein corresponding to at least one infor",alion
category available therein. At least one of the remote information terminals includes
a user-interface allowing a user to demand information in a selected inrunllalion
service caleuory. The terminal then seeks to user demanded information service
items in the selected category by monitoring at least one of the radio signal
l,a"sn,issions and col"paring information service category indicia therein to the
demanded information category.
The subject matter of the present invention is particularly pointed out and
distinctly claimed in the concluding portion of this specification. However both the
organization and method of operation of the invention together with further
advantages and objects thereof may best be understood by reference to the
following description taken with the accG",panying drawings wherein like reference
characters refer to like elements.
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BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention and to show how the same may
be carried into effect reference will now be made by way of example to the
accompanying drawings in which:
FIG. 1 illustrates a personal information terminal receiving both conventional
audio radio signal and data signal transmissions from FM radio stations.
FIG. 2 illustrates in block diagram the personal information terminal of FIG. 1.
FIG. 3 illustrates generally information services on demand by user system
enco",~assing three distinct geographic areas.
FIG. 4 illustrates in more detail signal transmission facilities of the system of
FIG. 3.
FIG. 5 illustrates a data packet transmission protocol employing multiple
frequency transmission wherein each ll ~nsr"ission references similar but relatively
offset time frames in a time-division multiplexed transmission protocol.
FIG. 6 illustrates a second form of a personal information terminal receiving
selected Wor"~alion service items on user demand in accorda"ce with the present
invention.
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FIG. 7 illustrates generally programming in the paging system receiving
information service data and distributing subsets of information service data among
transmission channeis.
FIG. 8 illustrates programming for information terminals showing normal
paging message reception and also showing information service reception
accordil,g to user demand.
FIG. 9 illustrates personal information terminal pro~"a",r"ing further detailing
on demand information service reception in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 illustrates a personal i"ror",dlion terminal 106 operating in accordance
with the present invention. FIG. 2 illustrates terminal 106 in block diagram.
Generally, terminal 106 is a combined audio and data FM radio signal receiving
device. With reference to FIG. 1, each terminal 106 includes a liquid crystal display
(LCD) 301 for presentation of FM radio tuning information and, as explained more
fully hereafter, and a LCD 300 for presentation of paging messages and inror",alion
services provided on demand in accordance with the present invention. Terminal
106 includes an AM/FM switch 180 as well as a volume dial 182 and tuner dial 184
to receive and present to the user a conventional audio signal.
In FIG. 2, each terminal 106 includes an antenna 186 coupled to receivers
188a and 188b. Receivers 188a and 188b produce baseband composite signals
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190a and 190b applied to bandpass filters 191 and 192, respectively. Bandpass
filter 199 monitors a subcarrier signal for application to a data decoder 193.
Bandpass filter 192 extracts a main audio channel for application to a stereo
decoder 194. Stereo decoder 194 applies right and left audio channels to a stereo
amplifier 195, which in turn drives right and left speakers 196 according to volume
control 182. Data decoder 193 drives a data presentation and storage block 197.
Each of receivers 188a and 188b may be selectively tuned to a given
broadcast frequency whereby a selected main audio signal and selected data
transmission are received concurrently from one or more FM radio stations. A
single frequency agile receiver may be employed to receive audio signal
transmissions, but during brief, e.g., 35 millisecond, intervals receive paging
message data packets on the same or a different bro~dc~st frequency. While such
brief loss of the audio signa! would possibly be audible to the user, the audio signal
would be generally c~",prehensible. The present embodiment, however, will be
shown with two separate receivers 188a and 188b, each individually tunable to a
selected FM station to receive audio and data transmissions, respectively.
A proyl~,llrl'able controller 170 orchestrates generally operation of terminal
106 including monitoring buttons 302, 304, and 306 and FM radio controls 180 and
184. Controller 170 activates and tunes receivers 188a and 188b and dictates
operation of data presentation and storage block 197 and of data decoder 193.
Thus, each terminal 106 monitors both selected audio and selected data
transmissions.
~7
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FIG. 3 illustrates generally an i"rur",alion service on demand by user system
encompassing three distinct geographic areas 1 00a, 1 00b, and 1 00c, in the
illustrated embodiment city A, city B, and city C, respectively. Each city or area 100
includes a plurality of radio signal transmission stations 102 each broadcasting, at
separ;ale frequencies and according to a given transmission protocol, a broadcast
signal 1 û4 to a plurality of personal information terminals (T) 106. Users of personal
information terminals 106 travel within a given city or area 100, or may travel
between areas 100.
Each personal i"ror",alion terminal 106 is a frequency-agile device capable
of tuning to selected frequencies, and thereby receiving information from a selected
one of stations 102, e.g., data and audio signals taken from different stations 102.
Data l,d"s",ission and reception within the information services system of FIG. 3
operates according to a given broadcast protocol. For example, the illustrated
system operates generally in the fashion of a paging system, or incorporated within
a paging system protocol. The present invention will be illustrated with reference to
a particular paging system protocol, but the invention is not limited to the particular
paging system and transmission protocol selected herein for illustration of the
present invention.
The present invention will be described in the context of a paging system as
disclosed in U.S. Patent Number 4,897,835 entitled HIGH CAPACIT'~ PROTOCOL
WITH MULTISTATION CAPABILITY and issued January 30,1990. In U.S. Patent
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Number 4,897,835, 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 broadcaslir,g 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 cor, e.;L 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. Receivers can be 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 con~ained 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.
FIG. 4 illustrates generally the transmission stations 102 of FIG. 3 as well as
delivery of information to stations 102 and coordinated information delivery among
the regions 100. In FIG. 4, a plurality of stations 102, each providing a separate
bro~dc~st signal 104, each include a subcarrier generator 120. Subcarrier
generalGrs 120 receive a data stream 122 from a paging system clearinghouse 124.
Subcarrier generalor~ 120 produce a subcarrier signal incorporated into the normal
=
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audio signal transmission, e.g., an FM signal transmission provided by a commercial
FM radio station comprising one of stations 102. Paging system clearinghouse 124
orchestrates delivery of paging data streams 122 to stations 102 accorcling to
paging system protocol. Such protocol includes not only fo", ldllirl~ and addressing
of paging information for reception by selected information terminals 106, but also
relative offset in paging data signal transmission among the stations 102.
Clearinghouse 124 interacts through a public switch telephone network (PSTN) 126
with a plurality of telephones 128, represented by a single telephone 128 in FIG. 4.
Telephones 128 allow callers to submit paging messages to clearinghouse 124 for
delivery to selected information terminals 106. Further, users of terminals 106
employ telephones 128 to interact with paging system clearinghouse 124 when
necesS:~ry.
Clearinghouse 124 also receives by way of telephone network 126
inrur,,,alion service items originating from inror",dlion sources 130. Information
sources 130 submit iuror"~alion in a variety of categories to clearinghouse 124. In
this manner, the paging system makes available i~rur~alion services in distinct
r~le~ories to users of terminals 106. Clearinghouse 124 further includes an
i"ler~ link 132 coupling clearinghouse 124 in a given area 1ûO with a
corresponding clearinghouse 124 in a se,uardle area 10û. In this manner,
coordinated distribution of paging messages and inror",a~ion services results among
the areas 1 OOa-1 OOc.
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FIG. 5 illustrates generally the time-division multiplexed protocol dictating
operation of stations 102 and personal information terminals 106. Each personal
information terminal 106 monitors a selected broadcast signal 104 during at least
one time slot 200 of an associated cyclically repeating time frame 202. Each time
frame 202 corresponds to one of stations 102, with a unique offset associated with
each station 102. Each time frame 202 includes a fixed number of time slots 200
each of fixed duration. Il Irur, "alion terminals 106 interpret the leading three time
slots, designated 200a, 200b, and 200c in FIG. 2, as control time slots. The
remaining time slots 200 in each time frame 202 carry data packets directed to one
or more members of the local population of personal inror"~alion terminals 106.
Personal information terminals 106 tune to a selected station 102 and
synchronize relative to the time frame 202 associated with that station 102. Each
terminal 106 stores therein a station list representing a set of stations 102 available
in a given area 100. By reference to the station list, an information terminal obtains
frequency values and relative time frame 202 offset values to selectively tune to
stations 102 in a given area 100, and thereby selectively obtain paging data and
inro""dlion services from a given station 102 and time slot 200.
Data packets transmitted during the control time slots 200a, 200b, and 200c
provide system information as discussed more fully hereafter. Each personal
inror",alion terminal 106 is associated with at least one of the remaining time slots
200 in each time frame 202. More typically, however, each terminal 106 is
associated with a set of time slots 200 within each time frame 202. Terminals 106
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each have a unique serial or identification number a portion of this number provides
a mask identifying a set of time slots 200 within each time frame 202. Each terminal
106 thereby identifies a set of time slots 200 assigned thereto. Each personal
information terminal 106 synchronizes operation relative to a selected station 102
and associated repeating time frame 202 to activate its radio signal receiving
circuitry and receive data packets transmitted during a targeted time slot 200.
Each station 102 broadcasts message data packets with reference to one of
repeating time frames 202, but time frames 202 are not in aligned synchronization.
Time frames 202 are offset relative to one another. This relative offset allows a
terminal 106 to switch frequencies, i.e., tune in a different station 102, and receive
more quickly a data packet during its assigned time slot. The terminal 106 need not
wait for the next assigned time slot in the original time frame 202. For example, if a
given terminal 106 finds corrupted data in a data packet provided during its
assigned time slot, it could wait until a next occurrence of an assigned time slot in
the current time frame 202. Relative offset among time frames 202 allows a terminal
106 to switch stations 102 and more quickly encounter an assigned time slot 200.
Radio stations 102 are, therefore, distinguished not only by distinct broadcast 104
frequencies of l,a-,sn,ission, but also according to a given relative offset of each
repeating time frame 202.
Each time frame 202 begins with control time slots 200a, 200b, and 200c.
Data packets l~dns",itted by a given station 102 during control time slots 200a-200c
provide a variety of configuration and system inro~",alion. Time slot 200a provides
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a data packet including a system flag 208. The system flag, in the illustrated
example comprising a 20 bit sequence "11110001111000110010", identifies to the
terminal 106 the paging system source of information provided in the broadcast
signal 104. Terminals 106 differentiate among one or more paging systems
employing similar L, d. ,smission protocol by reference to the system flag 208 leading
each time frame 202. As will be disc~ ~ssed more fully hereafter, variation in the
system flag available during control time slot 200a of each time frame 202 indicates
a sub-system within a given inror",dlion system. For example, sub-systems may be
designated for carrying particular categories of information, i.e., particular
information services.
Data l, ansmitted during control time slot 200b includes a variety of
configuration inror",dlion, including one or more information service codes 210.
Each code 210 indicates an ir~rur"~dlion service available in the associated
bro~dr~st signal 104. For example, a set of information codes designate one or
more of the following information services: weather, basketball scores, football
scores, hockey scores, Dow Jones index, transportation index, airline index, and
mutual funds index. For each information service available, a corresponding unique
code is assigned.
Terminals 106 seek particular in~ormation services in response to user
demand by monitoring stations 102 and receiving i"rc,r",dlion service codes 210,
and comparing received codes 210 to demanded codes 210. For example, a
terminal 106 seeks basketball scores by sequentially tuning to stations 102,
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monitoring the information codes 210 broadcast during a time slot 200b, and, upon
finding a station 102 broadcasli,lg basketball scores, receiving basketball scores
during a particular time slot 200 of the associated time frame 202. Similarly,
ter")i"als 106 seek particular information services in response to user demand by
monitoring broadcast 104 seeking a particular system flag 208, i.e., a system flag
208 associaled with a given one or set of information services. Information
terminals 106 need not have information subscription messages specifically directed
ll,ereto to receive selected information services. The ter",i"als 106 respond to user
demand by seeking information services according to the content of signal
broadcasts 104, i.e., by looking for particular service codes or particular system
flags.
Returning to FIG. 1, each terminal 106 includes a set of control buttons.
Activation of time button 30~ causes presentation of a current time and date on
display 300. The user activates button 304 to display stored or just-received paging
messages at terminal 106. Ir~ror"~alion service demand buttons 306, in the
illustrated embodiment individually designated 306a, 306b, 306c, and 306d, cause
terminal 106 to deviate from normal operation and seek information reflected in a
user i-,rur"~alion service demand initiated by user activation of one of buttons 306.
As illustrated, buttons 306a-306d correspond to weather, stock, football, and
basketball information services. Button 306 assignments, i.e., association with a
particular information service category may be fixed as illustrated in FIG. 1, or
proyrdllllllable according to a given design or product criteria. A user of a terminal
106 receives specific information services on demand without establishing such
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information through a prearranged subscription established by direct interaction with
the paging system operator.
While the particular terminal 106 shown has only four ir~rcr"~alion service
demand buttons 306, a variety of alternate button and user-interface configurations
may be employed to implement user demand for or reference to any desired number
of information categories.
For example, FIG. 6 illustrates a watch-form terminal 106'. In FIG. 6, an LCD
display 320 provides alphanumeric information in "scrolling" fashion, i.e., presents
textual information of significant length by scrolling through the display 320. The
watch-form terminal 106', being limited in physical size and number of user-interface
buttons available, makes multiple use of buttons 322 and 324. More particularly, in
a normal mode of operation, button 322, when activated by the user, causes
presentation of time and date information on display 320 and button 324, when
activated, c~uses presentation of paging mess~ 3es on display 320. By el.leril ,9 an
information services demand mode, however, the watch-form terminal 106' makes
aller"ale use of buttons 322 and 324. For example, by pressing both buttons 322
and 324 concurrently terminal 106' enters an information services demand mode
wherein button 322 sequentially presents inror",dlion service categories on display
320. When the user displays a desired ir,ror",alion service on display 320, the user
activates button 324 to select or demand information in that category.
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The watch-form terminal 106' thereby allows the user to "scroll and select"
among available information categories. Reference to a given inrorl,)alion category
causes the device to seek information within that category in accordance with the
present invention.
The invention will be described with reference to the terminal 106 as shown
in FIG. 1, but certain proylamnling and operation described also applies to the
watch-form terminal 106' wherein "scroll and select" operation of buttons 322 and
324 substitutes operation of buttons 306 in the terminal 106 of FIG. 1.
Each terminal 106 monitors user activation of buttons 306 and seeks
information services by switching to one or more stations 102 and by seeking an
appropriate ir,ror",alion service code 210 or switching sub-systems by seeking
broadcast signals 104 bearing an appropriate system flag 208. Each device 106
seeks a selected in r~l"~lion service code 210 or a system flag 208 to satisfy the
user-requested demand for a given inrGr~.alion service. Station 102 tuning under
normal multiple-frequency bro~d~st systems supports improved signal reception by
tuning to a better-received station 102. Station 102 selection under the present
invention is not for correcting bad reception, but rather to seek certain ir~rOrlllaliOn
services on demand without use of an alternate channel of communication, i.e.,
without calling the paging system operator.
FIG. 7 illustrates generally processing within the paging system directed to
reception of information service data and distribution among transmission channels.
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In FIG. 7, the paging system receives in block 400 information service data from a
variety of information sources. In block 402, subsets of information service data are
assigned to a~propriate transmission channels. More particularly, some information
services may be assigned to dedicated paging systems, i.e., systems bearing a
system flag 208 indicating broadcast of information services generally or particular
information services. Further, information service data may be assigned to
particular stations 102 within a given paging system. Thus, "transmission channel"
as indicated in block 102 refers to paging subsystems dedicated at least in part to
information service bro~rlc~st or to particular stations 102 dedicated in whole or in
part to delivery of particular inrc,r")dlion services. Continuing to block 404, the
paging system broadcasts the information service data according to transmission
channel assignment. In other words, information data is directed to an appropriate
transmission channel. In block 404, such bro~dc~-st may be intermixed with normal
paging bro~dr~sts or directed to dedicated paging subsystems or dedicated stations
102.
In any case, inror",alion service transmissions bear appropriate system flags
208 and information service codes 210 indicating the content of the transmission,
i.e., indicating the r~te9sry of inror",~lion service available in that transmission.
Thus, the paging system receives a set of information services and directs subsets
of information services received to specific transmission channels. In this manner,
overall system bandwidth is maximized by placing information service data on
dedicated transmission channels, thereby leaving relatively more transmission
bandwidth available for paging message delivery.
18
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FIG. 8 illustrates generally operation of an information terminal 106 receiving
normal paging messages, including messages generated by callers submitting
requests to the paging system clearinghouse 124 or information service
subscriptions as established by pre-arrangement with the paging system. In
addition, FIG. 8 illustrates response by the information terminal 106 to user
activation of buttons 306 in implementation of information services on demand by
user.
In FIG. 8, terminal 106 begins scanning generally for a data transmission in
block 500. Upon finding a data transmission, decision block 502 determines
whether a valid system flag 208 is present, i.e., the terminal 106 receives
information during a control time slot 200a. If a valid system flag is not present,
processing returns to block 500 for further scanning to detect data transmission. If a
valid system flag is found in decision block 502, processing advances to block 504
where terminal 106 stores the system station list including frequency and relative
time frame 202 offset values. In block 506, terminal 106 tunes to a system station.
Decision block 508 .leter.,.ines if the currently tuned system station 102 operates
accordi, .9 to a valid offset and frequency. If not, processing returns to block 506 to
tune to a next system station 102. If a valid frequency and offset are found in block
508, processing advances to block 510 where terminal 106 targets a next time slot
200 for the time frame 202 associated with the presently tuned station 102, i.e.,
ta. gels its assigned next time slot 200 to activate and receive information directed to
that particular terminal 106.
19
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Continuing to block 512 terminal 106 sets an interrupt for the next targeted
time slot to receive if present during that time slot 200 normal paging information
including i"ro""dLion service subscriptions as established by pre-arrangement with
the paging system. In block 514 terminal 106 interrogates buttons 306 to determine
user activation. If a user has activated one of buttons 306 processing branches to
block 516 where terminal 106 executes an information service demand procedure
(FIG. 9).
Processing eventually reaches block 518 where terminal 106 activates its
radio receiving circuitry and receives a data packet during the targeted time slot
200. Thus block 518 represents normal message reception accorcling to normal
paging system p,olocol including reception of inror",alion services as established
by pre-arrangement. Following block 518 processing returns to block 510 where
ter" ,i"al 106 tar~els a next time slot 200 according to system protocol. If terminal
106 loses contact with the presently tuned system station 102 processing returns to
block 506 where ter" ,inal 106 employs the system station list to select a next station
102 for reception of paging system i"ror",dlion.
FIG. 9 illu~lrales programming of terminal 106 as represented in block 516 of
FIG. 8. In FIG. 9 an information service demand procedure receives as parameters
a system flag 208 and an ir~ror"~alion service code 210. Activation of one of buttons
306 indicates to terminal 106 both a valid system flag 208 and a valid service code
210 for the user demanded information service. In block 600 terminal 106 scans for
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a valid information service system flag 208, i.e., one corresponding to the system
flag associated with the demanded ir,ror",dlion service. Decision block 602
determines if a valid information service flag 208 has been obtained. If not,
processing returns to block 600 for continued scanning in pursuit of a valid
information service system flag 208. When a valid information service flag 208 is
obtained, processing advances to block 604 where terminal 106 obtains a system
station 102 list. In block 606, terminal 106 tunes to a system station 102 and, in
decision block 608, determines if that station 102 provides a valid information
service code 210. In other words, tarS~ets the control time slot 200b of that station
102 and interrogates the information service codes 208 for a match with the
demanded information service. lf not, processing returns to block 606 where a next
system station 102 is tuned in pursuit of an appropriate information service code
210 therein. When a valid information service code 210 is obtained, processing
advances to block 610 where terminal 106 targets an i"form~lion service time slot
200 of the current time frame 202. In block 612, terminal 106 receives the
demanded i"ror",dlion service data for storage and presentation on display 300.
Thus, information services on demand by user has been shown and
described. The user need not interact directly with a paging system to receive
specific information services on a limited basis. A travelling user, upon entering a
new area 100 and activating one of buttons 306, indicates to terminal 106 a desired
i.,ror",~tion service. Terminal 106, in turn, seeks such inrorl"alion service without
prior knowledge of local station 102 frequencies or prior knowledge of systems irl
which such information services may be obtained. Terminals 106 seek information
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services by content, i.e., system flags 208 or information service codes 210, found in
broadcasts 104. The user merely presses a selected button 306 on its terminal 106,
and need not engage an alternate communication channel, e.g., telephone the local
paging system, to obtain particular information services on a limited basis and
without formal subscription therefor.
It will be appreci~ted that the present invention is not restricted to the
particular embodiment that has been described and illustrated, and that variations
may be made therein without departing from the scope of the invention as found in
the appended claims and equivalents thereof.
