United States Patent [19J
`Olson
`
`[54] METHOD TO ALLOW A RADIO
`TRANSCEIVER TO AUTOMATICALLY
`SELECT FROM AMONGST MULTIPLE
`RADIO SYSTEMS
`
`[75]
`
`Inventor: Carl B. Olson, San Carlos, Calif.
`
`[73] Assignee: Motor-0la, Inc., Schaumburg, Ill.
`
`[21] Appl. No.: 845,161
`
`[22] Filed:
`
`Mar. 27, 1986
`
`Related U.S. Application Data
`[63] Continuation-in-part of Ser. No. 687,104, Dec. 28,
`1984, abandoned.
`Int. CV ............................................... H04Q 7/00
`[51]
`[52] U.S. Cl . .................................. 45S/34.1; 455/54.2;
`455/56.1; 455/166.2; 379/58
`[58] Field of Search .................... 455/32.1, 33.1, 33.2,
`455/33.4, 34.1, 17, 54.1, 54.2, 56.1, 76, 77,
`166.2; 379/58
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`4,360,927 11/1982 Bowen et al. ...................... 455/54.1
`4,534.061 8/1985 Ulug ...................................... 455/17
`4,553.262 11/1985 Coe .................................... 455/34.1
`4,672,601 6/1987 Ablay .................................. 455/54.2
`
`I 111111111111111111111 lllll lllll lllll lllll 111111111111111111111111111111111
`US005261 l 17A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,261,117
`Nov. 9, 1993
`
`OTHER PUBLICATIONS
`Motorola® Systems Saber® FM Portable Radio Jan.
`1, 1990.
`Primary Examiner-Jin F. Ng
`Assistant Examiner-Philip J. Sobutka
`Attorney, Agent, or Firm-Steven G. Parmelee
`ABSTRACT
`[57]
`A method and means of automatically accessing several
`types of radio systems is described. The present inven(cid:173)
`tion allows a subscriber unit, which is normally opera(cid:173)
`tive in a operator selected radio system, to establish
`communication with an alternate system if a operator
`selected system cannot be found. The alternate system
`may be a conventional single channel mobile relay sys(cid:173)
`tem or trunked radio system in which the subscriber is
`authorized to operate. Once communications are estab(cid:173)
`lished with an alternate communication system, the
`present invention will periodically attempt to establish
`communication with the operator selected system while
`simultaneously attempting to be assigned a higher prior(cid:173)
`ity channel in the alternate communication systems
`according to a priority scan list. Further, the present
`invention will automatically ignore certain channels
`which are dedicated for car-to-car use.
`
`S Claims, 6 Drawing Sheets
`
`118
`
`116
`
`TO 116
`
`Ex.1024
`APPLE INC. / Page 1 of 12
`
`

`

`U.S. Patent
`
`Nov. 9, 1993
`
`Sheet 1 of 6
`
`5,261,117
`
`FIG.1A
`
`100
`
`..... ---
`
`118
`
`116
`
`TO 116
`
`122
`
`FIG.1B
`
`g
`
`INDICATOR
`
`VOLUME
`
`ON/
`OFF
`
`SYSTEM
`SELECT
`
`SUBFLEET
`
`120
`
`Ex.1024
`APPLE INC. / Page 2 of 12
`
`

`

`~ °' ~ ...
`...
`UI
`
`....J
`~
`~
`
`0\
`
`('I) -N
`
`00 =(cid:173)
`
`('I)
`
`0 ...,
`
`z 0
`
`\Q w
`\Q
`....
`~\Q
`~
`
`('t) = f"'t,-
`"ti = f"'t,-
`•
`~ • rJ).
`
`SPEAKER
`
`AMPLIFIER
`
`AUDIO
`
`-=
`
`2J0
`
`222
`
`228
`
`.-----, AMPLIFIER
`.. , AUD If NOGA TE
`
`1
`
`RE~~~~ER O
`
`226.
`
`SIGNAL
`OUTPUT _,.__.___.
`DATA 224·
`
`FIG.2
`
`314
`
`242 --
`
`~ (DATA) FROM
`INPUT SIGNAL
`TRANSMITTER
`
`FILTER ■-----.
`
`I LIMITER
`
`244
`
`I
`
`CILLATOR
`
`P.A. L
`
`340
`
`HI-LEVEL
`
`P.A.
`
`LOW-LEVE I g~NTROLLED ~ ,;;;;;;.)JI
`
`SYNTHESIZER~· 232
`
`I NO 2
`
`N0.11
`LO
`
`VOLTAGE
`
`ANO
`
`RF I
`
`220
`
`DETECTOR
`
`AUDIO
`r
`
`..r--1 FILTER
`CRYSTAL
`
`I
`
`FILTER
`CRYSTAL■
`
`218
`
`216
`
`214
`
`200
`
`212
`
`210
`
`208
`
`PRE-SELECTOR
`
`206
`
`Ex.1024
`APPLE INC. / Page 3 of 12
`
`

`

`U.S. Patent
`
`Nov. 9, 1993
`
`Sheet 3 of 6
`
`5,261,117
`
`FIG.3
`
`□
`
`:I:
`1-1
`("')
`::::0
`0
`"'tJ
`::::0
`0
`("')
`rr,
`Cl')
`Cl')
`0
`::::0
`
`I/0
`
`J14
`FILTER
`
`TRANSIMTTER
`!NPUT
`SIGNAL
`
`TO
`230
`
`224
`
`DATA
`OUTPUT
`SIGNAL
`RECEIVER UNMUTE
`PTT
`
`JOO
`
`Cl')
`Cl')
`~
`0::::
`C
`C <
`<
`I-<
`C
`
`232
`SYNTHESIZER
`AND
`VOLTAGE
`CONTROLLED
`OSCILLATOR
`
`307
`
`RAM
`
`JOJ
`
`DATA
`
`SYSTEM
`SELECTOR
`AND
`BUFFER
`
`SUBFLEET
`SELECTOR
`AND
`BUFFER
`
`J04
`
`J06
`
`JOB
`
`ROM/
`CODE PLUG
`
`Ex.1024
`APPLE INC. / Page 4 of 12
`
`

`

`U.S. Patent
`
`Nov. 9, 1993
`
`Sheet 4 of 6
`
`5,261,117
`
`START
`
`400
`
`F IG.4A
`
`414
`
`F =O
`s
`
`417
`
`YES
`
`F =O
`s
`
`Ex.1024
`APPLE INC. / Page 5 of 12
`
`

`

`U.S. Patent
`
`Nov. 9, 1993
`
`Sheet 5 of 6
`
`5,261,117
`
`422
`
`NO
`
`C=N
`START 0
`SELECT CHANNEL
`
`420
`HALT ANO WAIT
`FOR SYSTEM
`SELECTOR SWITCH
`CHANNEL
`
`426
`
`4JJ
`
`Fs=1
`MARK SEQUENC
`LOCATION
`
`Fs=O
`CONTINUE IN
`SCAN
`
`L
`
`464
`
`NO
`
`462
`
`F IG.4B
`
`Ex.1024
`APPLE INC. / Page 6 of 12
`
`

`

`U.S. Patent
`
`Nov. 9, 1993
`
`Sheet 6 of 6
`
`5,261,117
`
`FIG.4C
`
`Ex.1024
`APPLE INC. / Page 7 of 12
`
`

`

`1
`
`5,261,117
`
`2
`covered by the combination of trunked systems and
`mobile relays.
`
`METHOD TO ALLOW A RADIO TRANSCEIVER
`TO AUTOMATICALLY SELECT FROM AMONGST
`MULTIPLE RADIO SYSTEMS
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`This application is a continuation-in-part application
`based on U.S. patent application Ser. No. 687,104, filed
`Dec. 28, 1984, now abandoned.
`
`FIELD OF THE INVENTION
`This invention relates generally to the field of
`trunked radio systems and specifically to a method and
`means for automatically maintaining communications
`with a trunked or conventional mobile relay system as
`the mobile or portable unit moves from the radio cover(cid:173)
`age of one system to the radio coverage of another.
`
`5
`
`10
`
`SUMMARY AND OBJECTS OF THE
`INVENTION
`Briefly described, the present invention contemplates
`a method and means of automatically establishing com(cid:173)
`munication on an available communications channel in
`an area having a plurality of trunked and conventional
`communications systems. According to the principles
`of the present invention, a communicaton channel is
`established by searching for a communication channel
`on the preferred home trunked or conventional system,
`and remaining on that channel if one can be found. If a
`15 prime channel cannot be found, the mobile unit searches
`for an alternate channel according to a prearranged
`scan list. The mobile unit then locks onto the alternate
`channel if the alternate repeater responds with an ac(cid:173)
`knowledgement when interrogated. The mobile unit
`20 periodically attempts to reestablish communications on
`the preferred home system on a periodic basis; and
`simultaneously attempts to be assigned a higher priority
`channel on the alteniate communication system if a
`channel on the home system cannot be found.
`Accordingly, it is an object of the present invention
`to provide a method and means of expanding the range
`of a trunked system subscriber unit by providing the
`ability to seek out alternate communication systems.
`It is another object of the present invention to pro(cid:173)
`vide a method for automatically selecting the highest
`priority communication channel available to a suscriber
`unit.
`It is still another object of the present invention to
`35 provide a method and means of preventing the total loss
`of communications in a subscriber unit due to the un(cid:173)
`availability of a prime communication channel.
`It is yet another object of the present invention to
`provide a mobile subscriber unit which is compatible
`with plurality of communications systems.
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. IA is a drawing depicting the use of the present
`invention over a wide geographic area having several
`45 communication systems.
`FIG. 1B is a diagram of the control panel ofa mobile
`radio of the type which may advantageously utilize the
`method of the present invention.
`FIG. 2 is a schemaic diagram of a mobile receiver of
`the type which may advantageously utilize the method
`of the present invention.
`FIG. 3 is a schematic and block diagram of the pro(cid:173)
`cessing portion of the receiver of FIG. 2.
`FIGS. 4a-c comprise a flow diagram detailing the
`step-by-step execution of the method of the preferred
`embodiment of the present invention.
`
`DETAILED DESCRIPTION OF THE
`DRAWINGS
`FIG. 1 represents a three site system consisting of a
`trunked system 106 and two mobile relay systems 110
`and 114. Three different mobiles 102, 108 and 112 are
`also shown. The two mobile relays 110 and 114 transmit
`and receive their audio from a central dispatch point,
`104 via telephone circuits 116 and 118. These relays
`could alternatively be served by other carrier circuits
`such as microwave or fiber optics; or a configuration
`using remote controlled control stations. Mobile 108
`
`BACKGROUND OF THE INVENTION
`Trunked radio systems have developed as a means of
`increasing user mobile or portable units capacity in
`systems which operate in a fixed geographic area. In the
`past, a typical system was comprised of either a conven(cid:173)
`tional mobile relay system or a single site trunked sys- 25
`tern.
`A conventional mobile relay system may be com(cid:173)
`prised of a full duplex transceiver, receiving and trans(cid:173)
`mitting the audio signal to a fleet of mobile or portable
`units operating on the reverse pairing of those frequen- 30
`cies. This provides extended unit to unit coverage
`within the coverage area of the mobile relay. The ca(cid:173)
`pacity of a mobile relay system is severely limited by the
`number of users and the frequency and length of partic(cid:173)
`ular calls.
`Trunked systems alleviate the constraints of a single
`mobile relay system by operating on several alternative
`frequency pairs, and communications between units is
`done on channels which are dynamically assigned to
`them by a control unit on a separate control channel 40
`pair. In effect, trunking systems provide for automatic
`channel assignment in a mobile or portable radio.
`Trunked radio systems improve both spectral efficiency
`and operating characteristics of land mobile radio sys(cid:173)
`tems.
`Coverage from a given radio site is limited by Federal
`Communications Commission rules and regulations
`which require reducing the effective radiated power
`output of the mobile relay or trunked transmitter as the
`height above the average terrain is increased. This, in 50
`conjunction with local terrain and buildings, results in
`limited coverage from a single site.
`Increasing the amount of coverage may be accom(cid:173)
`plished by constructing additional trunked systems or
`mobile relays on additional sites to provide coverage in 55
`the desired areas. The selection of another trunked
`system or a mobile relay is an economic one, based on
`the coverage desired and the number of units that will
`be served by the coverage of the additional site(s). Ad(cid:173)
`ditionally, the FCC has loading standards, measured in 60
`units per frequency pair, so that providing too many
`frequency pairs can put a system operator at risk of
`losing exclusive use of their frequency pairs.
`The selection of single mobile relays to "fill in" trou(cid:173)
`ble spots is the best selection but suffers from a loss of 65
`system discipline as the unit operator has been tasked
`with the manual selection of the correct trunked or
`mobile relay system as they travel through the territory
`
`Ex.1024
`APPLE INC. / Page 8 of 12
`
`

`

`5,261,117
`
`40
`
`3
`may be typically operating in the coverage area of mo(cid:173)
`bile relay 110. Mobile 112 may be typically operating in
`the coverage area of mobile relay 114. Mobile 102 may
`be operating in the overlap area of all three systems,
`106, 110 and 114.
`FIG. 1B represents a control panel of a mobile radio
`of the type which may advantageously utilize the
`method of the present invention. According to the prin(cid:173)
`ciples of the present invention, mobile 102 may auto(cid:173)
`matically operate on system 106 of FIG. lA by select- 10
`ing the automatic mode 122 on the mobile unit control
`head 120 of FIG. 1B and by selecting a trunking posi(cid:173)
`tion of selector switch 124. The control head 120 of
`FIG. 1B is the user interface portion of mobile unit 102
`of FIG. IA, and is typically installed in a location which 15
`is convenient to the user. The bulk of the electronic
`circuitry is typically disposed in a remote location to
`conserve space within the vehicle. Referring now to
`FIG. IA, as the mobile unit 102 moves out of the system
`106 to the coverage area of system 110, the mobile unit 20
`102 will transfer to the frequency pair of system 110.
`The mobile 102 will transfer to system 114 as it leaves
`the coverage area of 106 and 110. In the common over(cid:173)
`lap area of 110 and 114 which does not share any over(cid:173)
`lap with system 106, the mobile unit 102 will operate on 25
`the system which is highest in priority in the search list;
`i.e. remote site 110.
`Mobile unit 102 will operate on only the mobile relay
`systems 110 or 114 if conventional only operation is
`selected on system selector 124 of FIG. 1B, and the 30
`system of operation will be determined according to a
`prearranged search list. Mobile unit 102 will be manu(cid:173)
`ally locked to the operator's selection if the automatic
`selector, 122 of FIG. 1B, is turned off. A system subfleet
`selector switch, 126 of FIG. 1, selects the subfleet for 35
`trunking system operation only. If more than one
`trunked system is being searched for, only the prepro(cid:173)
`grammed subfleet will be searched for except on the
`trunked system that is selected by 124 which will search
`for the subfleet selected by 126.
`Conventional repeater systems are well known. A
`complete technical description of a conventional re(cid:173)
`peater system may be found in Motorola Instruction
`Manual 68P81025E60 entitled "Micor Base and Re(cid:173)
`peater Station". Similarly, a complete technical descrip- 45
`tion of a trunked radio system which may be used ad(cid:173)
`vantageously with the teachings of the present inven(cid:173)
`tion may be found in Motorola Instruction Manual
`68P81066E60 entitled "Trunked System Central Con(cid:173)
`troller." This and the abovementioned manuals are 50
`available from the technical writing services depart(cid:173)
`ment of Motorola Inc., 1301 E. Algonquin Rd.,
`Schaumburg II., 60196, and are herein incorporated by
`reference as if fully set forth herein.
`Referring now to FIG. 2, there is shown a schematic 55
`and block diagram of the receiving portion of a mobile
`unit which may be used advantageously with the teach(cid:173)
`ings of the present invention. The transceiver of FIG. 2
`may be constructed with any of several well known
`receiver components and many transceiver configura- 60
`tions would function satisfactorily in accordance with
`the teachings of the present invention. In the trans(cid:173)
`ceiver of FIG. 2, an R.F. signal is received and transmit(cid:173)
`ted through antenna 202 which is coupled to an antenna
`switch 204. The antenna switch selectively couples 65
`signals to the antenna depending on the operational
`mode of the transceiver 200. Received signals are cou(cid:173)
`pled from the antenna switch 204 to a preselector 206
`
`4
`which provides the primary stage of filtering the R.F.
`signal for a desired frequency. The output of preselec(cid:173)
`tor 206 is coupled to a dual conversion frequency con(cid:173)
`verter formed by mixers 208 and 212 and amplifier 210.
`5 A synthesizer circuit 232 controls the frequency which
`is recovered by the frequency converter by controlling
`the voltage controlled oscillator for the injection fre(cid:173)
`quency of mixer 208. The synthesizer 232 would typi-
`cally be referenced to a high stability oscillator 231. The
`injection signal of a second mixer 212 may also be pro(cid:173)
`vided by oscillator 231 through multiplier circuitry
`contained in synthesizer 232. Additional filtering of the
`received signal is provided by crystal filters 214 and
`218. Amplifier 216 compensates for signal losses caused
`by previous receiver circuitry.
`The audio output circuitry of transceiver 200 is
`formed by audio detector 220, an audio gate and pream(cid:173)
`plifier circuit 222, and an output amplifier 228 and
`speaker 230. The output of crystal filter 218 provides a
`signal suitable for further processing by the remainder
`of the audio output circuitry. In addition to audio pro-
`cessing, the audio detector 220 also recovers data from
`the received and filtered signal and provides the data
`signal to be used by the processing portion of trans(cid:173)
`ceiver 200. A squelch circuit (not shown) generates a
`receiver mute signal 226 which disables the audio out-
`put of receiver 200 in the absence of an acceptable sig(cid:173)
`nal.
`The transmitter portion of the transceiver 200 is
`formed by a microphone 244 which is coupled to audio
`processing circuitry 242. The processed audio signal is
`then applied to the synthesizer 232 through a level ad-
`juster 242. The R.F. output of synthesizer is then cou(cid:173)
`pled to the antenna switch 204 through R.F. amplifiers
`234, 236 which convert the R.F. signal to a suitable
`power level. A transceiver suitable for use in accor-
`dance with the teachings of the present invention is
`described in detail in Motorola instruction manual no.
`68P81043E50 entitled "Trunked Syntor X mobile ra(cid:173)
`dio" available from the technical writing services de(cid:173)
`partment of Motorola Inc., 1301 E. Algonquin Rd.,
`Schaumburg Ill., 60196, said manual herein incorpo(cid:173)
`rated by reference.
`Referring now to FIG. 3, there is shown a schematic
`and block diagram of the processing portion of the
`transceiver of FIG. 2. A microprocessor 302 provides
`both transceiver operational control functions as well as
`a number of data decoding and processing functions.
`The data signal 224 recovered by receiver 200 is cou(cid:173)
`pled to microprocessor 302 through a buffer circuit 310.
`The microprocessor 302 is further coupled to an address
`and data bus 303 which couples the microprocessor 302
`to the system and subfleet selector switch buffers 304
`and 306. The address and data bus 303 is also coupled to
`the synthesizer and voltage controlled oscillator 232 of
`FIG. 2. In the operation of the present invention, micro-
`processor 302 decodes and generates data signals in
`accordance with a predetermined signalling scheme.
`The generated data signals are coupled to the transmit(cid:173)
`ter input of synthesizer 232 through an adaptive filter
`314. The circuit components described in FIG. 3 are
`well known and any of several readily available compo(cid:173)
`nents may be used in accordance with the teaching of
`the present invention.
`Referring now to FIG. 4, there is a flow diagram
`describing the automatic access method of the present
`invention. When the automatic selection process is en(cid:173)
`abled at 402, decision 406 examines the system switch to
`
`Ex.1024
`APPLE INC. / Page 9 of 12
`
`

`

`5,261,117
`
`5
`determine whether a conventional or trunked system
`has been requested. If the selector is set to a trunked
`system, item 408 provides the radio with a stored list of
`potential data channels which the radio is authorized to
`operate. Item 408 then causes the radio to scan potential 5
`data channels according to the stored list. If a data
`channel is detected, decision 410 examines the activity
`on the channel to determine whether it is a proper data
`channel. If a proper data channel has been detected, the
`radio will lock onto the data channel and operate in the 10
`trunked system. Failing to find a data channel decision
`410 directs the radio to item 411 to search for a backup
`trunking channel. If a backup trunking channel is de(cid:173)
`tected, the radio will remain there until decision 416
`detects the loss of the data activity on the channel. If the 15
`backup data channel is lost, decision 416 causes the
`automatic mode to reset the scan flag and to restart at
`402. If decision 411 did not find a backup trunking chan(cid:173)
`nel, the method of the present invention uses decision
`412 to determine if the trunked system scan flag (F s) is 20
`set to one. If the flag is set to one then decision 413
`checks to see if the scan is complete. If the scan is com(cid:173)
`plete, the flag is reset by 414 and the process is restarted.
`If the scan is not complete the scan list location is incre(cid:173)
`mented by one, the flag is reset in 429 and control trans- 25
`fers back to 430 to continue the scan.
`If at item 412 the trunking scan flag was not set,
`control is transfered to 430 to start the scan list from the
`beginning. Decision 431 examines the first system in the
`priority scan list and determines whether the system is 30
`trucked. If the system is trunked then item 433 sets the
`trunked scan flag (F s) to one, stores the position of the
`system in the scan list and transfers control to item 408.
`If the system is non-trunked, control is transfered to
`item 432 to test for channel activity. If channel activity 35
`is not detected, item 434 will interrogate the repeater to
`determine whether the radio is within the operating
`area of the particular repeater. If channel activity is
`detected, item 433 allows the radio to receive on the
`appropriate channel but prevents the interrogation, 434, 40
`of the mobile relay until the channel activity has ceased.
`The decision 436 is based on whether the mobile relay
`acknowledges the interrogation with a valid response.
`If decision 436 detects a valid response, item 438 will be
`selected and the radio will temporarily operate on the 45
`conventional mobile relay system. At this moment, two
`concurrent timing sequences are initiated at process
`448. While most microprossessors and microcomputers
`are capable of executing a single instruction at a time,
`techniques are well known for allowing a microproces- 50
`sor to execute more than one process and provide essen(cid:173)
`tially concurrent operation among several processes.
`The process initiated at item 450 provides a time keep(cid:173)
`ing function. Item 450 sets the contents of an acknowl(cid:173)
`edgment timer to a value which may be intergrally 55
`incorporated into the operating program or retrieved
`from the contents of memory which may be set accord(cid:173)
`ing to user preference. This value would typically be on
`the order of 60 seconds. An alternate timing sequence
`begins with decision 466 and will be fully discussed 60
`below.
`Item 452 provides a counter or clock register which
`is incremented once a second while the other portions
`of the present method are being executed. This leads to
`two decision blocks. Decision 454 examines items 450 65
`and 452 and determines whether the time limit has been
`exceeded. Decision 456 determines whether an ac(cid:173)
`knowledgment has been received during the time inter-
`
`6
`val set by items 450 and 452. If the decision 454 has not
`detected that the interval has timed out and, decision
`456 has decoded an acknowledgment, then the conclu(cid:173)
`sion is that another user has entered the system and the
`value of the acknowledgment timer, 450, should be
`incremented to a higher value and the timer, 452, re(cid:173)
`started at zero. This function is represented symboli(cid:173)
`cally by AND gate 458 and item 460.
`Should the timer decision 454 exceed the time inter(cid:173)
`val set by items 450 and 452 and decision 456 has not
`decoded an acknowledgment, the radio must reinterro(cid:173)
`gate the mobile relay to continue its operation. The
`symbolic AND gate 462 activates item 464 under this
`condition. Item 464 sets a re-interrogation flag (FR) and
`decision 432 is selected to determine whether there is
`any current channel activity. As noted above, if there is
`no current channel activity, item 434 will cause an inter(cid:173)
`rogation to be sent. At this point, if decision 436 indi(cid:173)
`cates an acknowledgment has been decoded, then the
`loop has been completed and the radio will continue to
`operate on the system, subject to the other timing se(cid:173)
`quences and the re-interrogation loop just completed.
`If at decision 436 no acknowledgment was decoded,
`then decision 440 checks to see whether a re-interroga(cid:173)
`tion is indicated that is, the flag FR equals one. If deci(cid:173)
`sion 440 determines that the flag has been set, then the
`radio clears the re-interrogation flag at item 442 by
`setting FR equal to zero and the process starts over
`again at 402. If decision 440 determines that the flag has
`not been set, then it is known that the radio has not
`found a channel yet and decision 444 is selected to de(cid:173)
`termine whether the radio has exhausted the possibili(cid:173)
`ties stored in the scan list. If the scan list has been ex(cid:173)
`hausted, decision 444 causes the process to be started
`over at 402. If the scan list has not been exhausted, then
`the scan list is incremented by one at item 446, and the
`radio again starts the loop at decision 432, on the next
`channel in the sequence.
`The other timing sequence initiated by process 448
`begins with decision 466. Decision 466 is similar to
`decision 406 in that the system selector is reviewed to
`determine whether the operator requested a trunked or
`conventional system for their primary communications.
`If decision 466 determines that conventional communi(cid:173)
`cations have been requested, then the conventional
`retry timer 468 is set to a predetermined value, for ex(cid:173)
`ample, 120 seconds. As with the timers described above,
`this value may be integrally incorporated into the oper(cid:173)
`ating program or alternatively be stored in a code plug
`or memory location which is read to determine the
`value of the retry interval. The timer formed by item
`470, is incremented once per second until decision 472
`indicates that the proper interval has occurred. This
`interval is the Tc time interval ANDED with no ocur(cid:173)
`rence of push-to-talk for 20 seconds. If decision 474
`determines that the radio is operating on the channel
`selected on the system selector, the decision loop is
`repeated. If the output of decision 474 determines that
`the radio is not operating on the channel selected on the
`system selector, and decision 476 determines that there
`is no channel activity, the radio will be programmed to
`the channel selected by the system selector by item 478.
`Decision 480 is selected to determine whether there is
`channel activity on the newly selected channel. If deci(cid:173)
`sion 480 detects activity, and decision 486 indicates the
`proper subaudible tone or data is present, the program
`will proceed to item 438 and lock onto the channel
`which is indicated on the system selector. If decision
`
`Ex.1024
`APPLE INC. / Page 10 of 12
`
`

`

`5,261,117
`
`50
`
`7
`486 indicates an improper subaudible tone or data, then
`the program will transfer to item 430 to start from the
`top of the search sequence. If the decision 480 deter(cid:173)
`mines that the channel is not active, then item 482 will
`generate an interrogation. If an acknowledgment is 5
`decoded by decision 484, then the radio will proceed to
`item 438. If an acknowledgment is not decoded by deci(cid:173)
`sion 484, then the program will transfer to item 430
`which restarts the search from the top of the search
`scan list. When entry into block 430 was preceded by to
`decisions 484, 486, or 499, the scan list is modified to
`place the last used channel above the scan list. This
`speeds-up the reacess time. During the initial pass(cid:173)
`through block 430, there was no last used channel and
`the process starts with the normal priority list.
`If the decision 466 was no, then the radio should be
`retrying to reaccess the selected trunked communica(cid:173)
`tions system. Item 488 sets the trunking retry interval to
`120 seconds. The timer interval is stored in a manner
`which is identical to the values of the timers described 20
`above The timer formed by item 490 is started and
`incremented once a second until decision 492 indicates
`that the time interval has elapsed. This interval is the Tb
`time interval ANDED with no occurrence of push-to(cid:173)
`talk for 20 seconds. If decision 493 determines that the 25
`radio is operating on the system selected by the system
`selector, the decision loop is repeated. If the output of
`decision 493 determines that the radio is not operating
`on the channel selected on the system selector then
`decision 494 checks for channel activity. If channel 30
`activity is not occuring on a backup channel, the system
`will wait until the activity ceases before transfering to
`item 496. If the backup data word is decoded, by item
`495 the selection of item 496 will occur without delay.
`Item 496 will check the previously defined trunking 35
`sequence, and program the radio to operate on the
`trunked system according to the trunking sequence.
`Decision 498 transfers program control to item 408 if a
`data channel has been found. If the date channel se(cid:173)
`quence was not found, decision 498 selects decision 499 40
`which looks for a backup channel. Ifno backup channel
`is found, decision 499 restarts the timer loop by setting
`490 back to zero, and transfers control to 430. If deci(cid:173)
`sion 499 detects that a backup channel was found, then
`the program transfers to decision 416 which holds the 45
`radio on the backup channel until the backup channel
`identifying data word is lost. if the backup channel is
`lost. the program exits decision 416 where item 417
`resets the trunking scan flag and the entire routine is
`started from the beginning, 402.
`The final path possible exists if the decision 406 indi(cid:173)
`cates that a conventional channel has been selected. If
`decision 406 indicates that a conventional channel has
`been requested, decision 418 determines whether the
`conventional selection is a simplex (car-to-car fre- 55
`quency). If decision 418 determines that a car-to-car
`frequency has been requested, then the automatic pro(cid:173)
`cess must be halted and item 420 is selected, as there are
`no mobile relays in this configuration to respond with
`acknowledgments. The instructions executed by item 60
`420 allow the radio to operate on the selected channel
`until the system selector is changed which restarts the
`program at 402. If decision 418 determines that a car-to(cid:173)
`car frequency has not been requested, then item 422 will
`program the radio to the channel indicated on the sys- 65
`tern selector and decision 424 checks for channel activ(cid:173)
`ity. When there is no activity, decision 424 selects item
`426 and an interrogation will be sent. If the decision 428
`
`8
`indicates that an acknowledgment was decoded, then
`the radio will lock onto that channel at item 438. If
`decision 428 determines that an acknowledgement was
`not successfully decoded, then item 430 will be selected
`and the conventional system scan process will be initi~
`ated.
`In summary, a method and means for multi-system
`operation has been described. According to the princi(cid:173)
`ples of the present invention, a communication channel
`is established by searching for a communication channel
`on the selected trunked or non-trunked system, and
`remaining on that channel if one can be found. If the
`selected channel cannot be found, the mobile unit
`searches for an alternate system according to a prear-
`15 ranged scan list. The mobile unit then locks onto the
`alternate channel if the alternate non-trunked system
`responds with an acknowledgement when interrogated,
`or if the trunked system data channel is found. The
`mobile unit attempts to reestablish communications on
`the operator selected system on a periodic basis, and
`simulta!leously attempts to be assigned a higher priority
`channel on the alternate communication system scan list
`if the operator selected system cannot be found, and the
`current alternate system cannot be reacquired. Accord(cid:173)
`ingly, other uses and modifications will be obvious to
`one of ordinary skill in the art without departing from
`the spirit and scope of the principles of the present
`invention.
`I claim:
`1. A method of controlling a portable or mobile trans(cid:173)
`ceiver for automatically seeking an available communi(cid:173)
`cations system if a operator selected communication
`system is not available in an area having a plurality of
`trunked and non-trunked communications systems, said
`method comprising the steps of:
`(a) searching for a communication channel on an
`operator selected trunked or non-trunked commu(cid:173)
`nication system, and remaining on that system if it
`can be found;
`(b) searching for an alternate channel on another
`trunked or non-trunked communication system
`according to a prearranged priority scan list, if said
`operator selected system cannot be found;
`(c) locking onto an alternate non-trunked system if
`the alternate non-trunked system responds with an
`acknowledgement when interrogated, or locking
`onto a trunked system upon detecting a trunked
`system data channel;
`(d) periodically attempting t