United States Patent
`Marni et a1.
`Feb. 26, 1991
`[45] Date of Patent:
`
`{11] Patent Number:
`
`4,996,715
`
`[19]
`
`[54] RADIO TELEPHONE APPARATUS
`
`[75]
`
`Inventors: Kuniyoshi Marni, Saitama; Kiyoshi
`Hattori, Tokyo, both of Japan
`
`[73] Assignee: Kahushiki Kaisha Toshiba, Japan
`[21] Appl. No.: 248,921
`
`4,775,995 10/1988 Chapman et al. ..................... 379/58
`4,802,201
`1/1989 Yoshizawa et al.
`.................. 379/62
`
`Primary Examiner—Douglas W. Olms
`Assistant Examiner—Min Jung
`Attorney, Agent, or Firm——Banner, Birch, McKie &
`Beckett
`
`[22] Filed:
`
`Sep. 21, 1988
`
`[57]
`
`ABSTRACT
`
`Foreign Application Priority Data
`[30}
`Sep. 29, 1987 [JP]
`Japan ................................ 62-24462}
`
`Int. (31.5 ............................................... H04Q 7/04
`[51]
`[52} us. C1. ........................................ 455/33; 455/54;
`379/60; 379/63
`[58] Field of Search ..................... 455/33, 54, 67, 229,
`455/68, 69; 379/60, 70, 71, 61, 53, 59, 63;
`340/511
`
`{56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,032,723 6/ 1977 Mendoza ............................... 379/61
`4,475,010 10/ 1984 Huensch et a1.
`.
`.. 379/60
`
`4,593,273
`6/1986 Narcisse .......
`340/539
`4,761,806
`8/1988 Toki ...................................... 379/61
`
`Radio telephone apparatus for use in a cellular mobile
`telephone system comprises means for alarming at least
`a user operating the apparatus in response to a drop in
`signal strength of radio frequency signals received over
`an established communication channel when the appa—
`ratus approaches a boundary of service area in a cellular
`mobile telephone system. The signal strength is repeti-
`tively checked to determine if it has fallen below a first
`predetermined signal strength value. When the signal
`strength falls to or below a second predetermined signal
`strength value, the radio telephone apparatus causes a
`disconnection of the telephone link and returns the
`apparatus to a standby mode.
`
`24 Claims, 3 Drawing Sheets
`
`NICROPROCESSOR
`
`I4
`
`16
`
`[5
`
`_
`
`
`
`
`
`DISPLAY
`UNIT
`
`I
`
`CONVERTER
`
`RECEIVER
`
`BASEBAND UNIT
`
`ANTENNA
`COUPLER
`
`.
`
`
`
`
`I___-_!I
`
`
`
`
`
`.TRANSNITTER-
`BASEBAND UNIT
`LI!
`
`,/
`
`2I
`
`2
`
`
`
`I
`
`18
`
`I9
`
`0
`
`
`
`
`
`SPEECH
`
`SYNTHESIS
`
`
`UNIT
`
`
`EXHIBIT
`Petitioner - Kyocera
`
`PX 1014
`
`Kyocera PX 1014__1
`
`

`

`U.S. Patent
`
`Feb. 26, 1991
`
`Sheet 1 of 3
`
`4,996,715
`
`FIG. I
`
`MICROPROCESSOR
`
`14
`
`161'1!
`
`BASEBAND UNIT
`
`12
`
`BASEBAND UNIT
`
`18
`
`19
`
`SPEECH
`SYNTHESIS
`UNIT
`
`FIG. 5
`
`400ms
`
`Kyocera PX 1014_2
`
`

`

`U.S. Patent
`
`Feb. 26, 1991
`
`Sheet 2 of 3
`
`4,996,715
`
`FIG. 2
`=====-----------------------------~22
`RECEIVER
`
`23
`
`II
`ANTENNA
`COUPLER
`
`~---+~BASEBAND
`UNIT
`
`AID
`CONVERTER
`
`24
`
`FIG. 3
`
`VOLTAGE
`(BINARY DATA)
`sv~----------------­
`UIIIIIII) --------------------------------------------
`
`ov
`(00000000)...___......._ ______________ _
`FIELD INTENSITY
`
`Kyocera PX 1014_3
`
`

`

`U.S. Patent
`
`Feb. 26, 1991
`
`Sheet 3 of 3
`
`4,996,715
`
`START
`
`FIG. 4
`
`Kyocera PX 1014_4
`
`

`

`1
`
`RADIO TELEPHONE APPARATUS
`
`4,996,715
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`This invention relates to the field of radio telephone
`apparatus and more particularly to a mobile telephone
`unit of a mobile telephone system.
`2. Description of the Relevant Art
`In cellular mobile telephone systems, a large geo(cid:173)
`graphical area is covered and served by breaking the
`area into a plurality of small zones or cells. Within the
`combined plurality of small zones, i.e., a service area, a
`mobile telephone is capable of establishing a communi(cid:173)
`cation link with another party. Outside the service area,
`however, the mobile telephone may not be served by
`the serving system. Accordingly, when a vehicle
`equipped with the mobile telephone leaves the service 20
`area and a communication link i.e., a speech line with
`another party has already been established, the commu(cid:173)
`nication link may suddenly be disconnected. This sud(cid:173)
`den break down of an established speech line displeases
`.
`users.
`
`10
`
`15
`
`2
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`An embodiment of the present invention will now be
`5 described with reference to the accompanying draw(cid:173)
`ings.
`FIG. 1 is a block diagram showing an arrangement of
`a mobile unit associated with one embodiment of the
`invention.
`Referring to FIG. 1, mobile unit 10 comprises an(cid:173)
`tenna coupler 11 for transferring signals from transmit(cid:173)
`ter section 12 to antenna 13 and for transferring signals
`from antenna 13 to receiver section 14, microprocessor
`15 for controlling elements of mobile unit 10, oscillator
`16 for generating tones, displaying unit 17 for displaying
`information sent from microprocessor 15, speaker 18 for
`outputting signals from receiver section 14 or from tone
`generated 16, microphone 19 for inputting signals to
`transmitter section 12, switch 34 controlled by micro(cid:173)
`processor 15, and speech synthesis unit 35 for synthesiz(cid:173)
`ing predetermined speech patterns.
`Transmitter section 12 includes baseband unit 20 cou(cid:173)
`pled to an input speech signal for processing signals at
`baseband frequency and transmitter 21 coupled to the
`output of baseband unit 20 for modulating the output
`signal to be broadcast via antenna coupler 11 and an(cid:173)
`tenna 13. Receiver section 14 includes receiver 22 cou(cid:173)
`pled to antenna coupler 11 for demodulating received
`signals, baseband unit 23 coupled to the output of re(cid:173)
`ceiver 22 for processing the received signals, and AID
`converter 24 for converting an analog signal supplied
`thereto to a digital signal responsive to control of mi(cid:173)
`croprocessor 15.
`More specifically, as shown in FIG. 2, receiver 22
`includes first signal source 25, mixer 26 for combining
`an incoming radio-frequency signal with the signal from
`first signal source 25, first I-F (intermediate-frequency)
`amplifier 27 for amplifying the output signal of mixer
`26, second signal source 28, mixer 29 for combining the
`output signal of first I-F amplifier 27 with signal from
`second signal source 28, second I-F amplifier 30 for
`amplifying the output signal of mixer 29, and I-F inte(cid:173)
`grated circuit (IC) 31. I-F IC 31 may comprise a plural-
`ity oflinear amplifiers 32 for amplifying received signals
`and a plurality of diodes 33 for detecting the strength of
`received signals.
`FIG. 3 shows the relationship between the voltage
`value detected by the plurality of didoes 33 and field
`intensity indicative of received radio frequency signal
`strength. The detected voltage value, for example 0-5
`volts is converted to a digital value having a range, for
`example of 00000000-11111111 by AID converter 24.
`This digital value is applied to microprocessor 15.
`When the detected voltage value decreases to a first
`predetermined value, for example, 1 volt, microproces-
`sor 15 controls switch 34 so that the tone output of
`oscillator 16 is applied to speaker 18 and transmitter
`section 12, thereby an alarm sound generated via
`speaker 18 is likewise transmitted to the radio channel
`via transmitted section 12. When the detected voltage
`value decreases to a second lower predetermined value,
`for example, 0 volts microprocessor 15 controls transis(cid:173)
`tor section U so as to terminate broadcasting and re(cid:173)
`ceiver section 14 so as to receive signals of a telephone
`signal link control channel. A voice synthesized alarm
`may also be provided by voice synthesis unit 35 as de(cid:173)
`scribed below.
`
`25
`
`SUMMARY OF THE INVENTION
`It is accordingly an object of the present invention to
`provide a radio telephone apparatus in which a user 30
`may know in advance that their vehicle in which their
`cellular telephone apparatus is installed is approaching a
`boundary of the service area.
`To achieve the object and in accordance with the
`purpose of the present invention, as embodied and de- 35
`scribed herein, the invention comprises means for re(cid:173)
`ceiving signals transmitted over a radio channel; means
`coupled to the receiving means for measuring the
`strength of the received signals; signal generating means 40
`coupled to the measuring means, and, in the event that
`a communication link using the channel bas already
`been stabilized, the signal generating means generating
`a first signal in response to the detection of a signal
`strength measured by the measuring means below a first 45
`predetermined value and generating a second signal in
`response to a decrease in signal strength to or below a
`second predetermined value; means responsive to the
`first signal for alarming at least one user of the appara- 50
`tus; and means responsive to the second signal for caus(cid:173)
`ing a disconnection of the communication link.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a schematical block diagram showing an 55
`arrangement of radio telephone apparatus associated
`with an embodiment of the present invention;
`FIG. 2 is a scbematical block diagram mainly show(cid:173)
`ing the detail of the receiver in FIG. 1;
`FIG. 3 is a graph of signal field strength versus volt- 60
`age showing the relationship between the voltage value
`detected by detectors and field intensity indicative of
`the strength of received signals;
`FIG. 4 is a flow chart of an algorithm showing the 65
`indication operation of the embodiment; and
`FIG. 5 is a time chart for explaining the provision of
`an alarm by the embodiment.
`
`Kyocera PX 1014_5
`
`

`

`4,996,715
`
`3
`Now the operations of mobile unit 10 in accordance
`with the embodiment will be described in reference to
`FIGS. 4 and 3.
`In this embodiment, the strength of received radio
`frequency signals is checked after a predetermined time 5
`interval (steps 401, 402, and 403), for example, every
`five seconds. The time interval is counted down by a
`timer of microprocessor 15 or, alteratively, a peripheral
`unit thereto. After the time delay expires at step 402, the
`microprocessor continues to step 403.
`If the digital value corresponding to the detected
`signal voltage at step 403 is equal to or lower than the
`digital value corresponding to the first predetermined
`voltage value (step 404), for example 1 volt, micro(cid:173)
`processor 15 activates switch 34 so that the output of 15
`oscillator 16 is applied to speaker 18 and to transmitter
`section 12, thereby an alarm tone generated by oscilla-
`tor 16 is sounded via speaker 18 and also transmitted to
`the radio channel via transmitter section 12. Therefore
`this alarm may also be heard by the other party to the 20
`conversation. If the overall duration of the alarmer is
`400 ms, for example, comprising a repeating nonsilence
`duration of 100 ms and a silence duration of 50 ms as
`shown in FIG. 5, users may easily perceive the alarm
`sound as distinct from other telephone signals and the 25
`alarm may not significantly interfere with the telephone
`conversation. Furthermore microprocessor 15 may
`control display unit 17 so that an alarm message, for
`example, "NEAR BOUNDARY" OR "speech line
`DISCONNECT SOON" is displayed. Microprocessor 30
`15 may simultaneously control speech synthesis unit 35
`so that an alarm message is sounded via speaker 18 and,
`on the other hand, transmitted to the radio channel via
`transmitted section 12 typically after the audible peri(cid:173)
`odic tone (FIG. 5) is sounded. In this case, speech syn- 35
`thesis unit 35 may artificially synthesize speech on the
`basis of prestored data or reproduce spoken words of
`the user which have been stored in advance (step 405).
`On the other hand, in the event that the digital value
`corresponding to the detected voltage returns to a level 40
`above the digital value corresponding to the first prede(cid:173)
`termined value (step 404) in the next iteration (the pre(cid:173)
`determined time interval has lapsed) or measurement at
`step 411, microprocessor 15 terminates displaying the
`alarm message if appropriate and the operation of mi- 45
`croprocessor 15 returns to step 401 (via steps 414 and
`415).
`Next microprocessor 15 checks whether the detected
`voltage value determined at step 403 is below a second
`predetermined value or has fallen to 0 voltage (step 407) 50
`after setting a timer to a second predetermined interval
`of, for example, 5 seconds (step 406). If the detected
`signal voltage is not below or has not fallen to the sec(cid:173)
`ond predetermined value, the operation of microproces(cid:173)
`sor 15 returns to step 401 to check the signal strength 55
`again to determine if it is below the first predetermined
`level. First, however, the timer turned on at step 406 is
`turned at step 413.
`If the detected voltage value determined at step 403 is
`at or below the second predetermined voltage value 60
`(step 407), it would be normally expected that the five
`second interval established at step 406 has not yet ex(cid:173)
`pired at step 408. Then the timer is set to a third prede(cid:173)
`termined interval of, for example, 5 seconds at step 409.
`Once the time expires at step 410, the signal level is 65
`checked against at step 411. At box 407, it is again deter(cid:173)
`mined that the signal value, for example, is 0 volts and
`the signal level has remained at or below the second
`
`4
`predetermined level. Now time has expired at step 408
`and the mobile telephone receiver returns to a standby
`mode at step 412. This entails causing a disconnection
`from the telephone link at a telephone central office
`including terminating a broadcasting from transmitter
`section 12. Also, receiver section 14 returns to a control
`channel for receiving telephone link controls signals. It
`may be seen that two sequential measurements of signal
`level at, for example, 0 volts are required before the link
`10 is caused to be disconnected.
`From the above description, the first predetermined
`value for signal strength may be assumed to equal the
`second predetermined value in one embodiment or may
`be greater than the second predetermined value in a
`second embodiment. If at step 403 (FIG. 4) the signal
`strength value decreases below either the first or second
`predetermined value (the values being equal in the first
`embodiment, an alarm tone generated by oscillator 16
`may be immediately sounded via speaker 18 and also
`transmitted to the radio channel via transmitter section
`12 (and other appropriate indications made, for exam(cid:173)
`ple, via display 17). Furthermore, microprocessor 15
`sets the timer to a second predetermined interval at step
`406 of, for example, 5 seconds. Consequently, unless the
`signal strength value recovers within the second prede(cid:173)
`termined interval, the communication link will be dis(cid:173)
`connected at step 412. During the second predeter(cid:173)
`mined interval of time, the several indications of an
`alarm initiated at step 405 continue to be indicated to at
`least one party to the conversation.
`In accordance with the second embodiment and in
`the event that the second predetermined value is not the
`same value but may be less than the first predetermined
`value for signal strength, two types of alarm indications
`may be initiated. A frrst alarm message of form in accor(cid:173)
`dance with the above i.e. NEAR BOUNDARY may be
`ordered at step 405. However, in the second embodi(cid:173)
`ment a second indication step may be provided between
`steps 409 and 410 such that in the first passage through
`loop 407-411 a more urgent indication is provided for
`the third predetermined interval. For example, if the
`signal strength value decreases below the second prede(cid:173)
`termined value, urgent types of indicia such as a more
`rapid periodic alarm tone or a more important displayed
`message such as "SPEECH LINE DISCONNECT
`IMMINENT'' may be provided until the third prede(cid:173)
`termined interval lapses.
`The frrst, second and third predetermined intervals at
`steps 401, 406 and 409 and preferably as short as 4-5
`seconds to insure that in-use channels are freed for use
`by others after a reasonable period of time.
`We claim:
`1. A cellular radiotelephone unit for use in a cellular
`radiotelephone system for serving one or more geo(cid:173)
`graphic areas formed of a plurality of cellular zones, the
`cellular radiotelephone unit comprising:
`receiving means for receiving radio signals transmit(cid:173)
`ted over a speech radio channel or a control radio
`channel;
`measuring means, coupled to the receiving means, for
`measuring the strength of the radio signals received
`by the receiving means;
`alarming means for alarming at least the user of the
`cellular mobile radiotelephone unit in response to
`the detection of a signal strength value measured
`by the measuring means at or below a first prede(cid:173)
`termined value after a communication link with a
`
`Kyocera PX 1014_6
`
`

`

`4,996,715
`
`10
`
`5
`second party using the speech radio channel is
`established; and
`control means for controlling the receiving means to
`· receive radio signals transmitted over the control
`radio channel, in stead of the speech radio channel, . 5
`in response to the detection of a signal strength
`value measured by the measuring means at or
`below a second predetermined value, the second
`predetermined value being no greater than the first
`predetermined value.
`2. The cellular radiotelephone unit of claim 1 wherein
`the alarming means comprises means for generating
`sounds and a related sound signal.
`3. The cellular radiotelephone unit of claim 2 further
`comprising means for broadcasting the generated sound 15
`signal over the communication link with the second
`party.
`4. The cellar radiotelephone unit of claim 2 wherein
`the sound generating means comprises speech synthesis
`means for synthesizing predetermined speech patterns. 20
`5. The cellular radiotelephone unit of claim 2 wherein
`the generated sounds and related sound signal comprise
`a periodic signal of less than one second duration in
`which short periods of tone are interleaved with shorter
`periods of silence.
`6. The cellular radiotelephone unit of claim 4 wherein
`the predetermined speech patterns simulate the voice of
`the user of the unit.
`7. The cellular radiotelephone unit of claim 1 wherein
`the alarming means comprises a visual display unit.
`8. The cellular radiotelephone unit of claim 1 wherein
`the first predetermined value of signal strength is equal
`to the second predetermined value of signal strength
`and the control means controls the receiving means to
`receive over the control radio channel when the signal 35
`strength value is at or below the first or second prede(cid:173)
`termined value and after the alarming means alarms the
`user of the apparatus.
`9. The cellular radiotelephone unit of claim 1 wherein
`the frrst predetermined value of signal strength is 40
`greater than the second predetermined value of signal
`strength.
`10. A cellular radiotelephone unit for use in a cellular
`radiotelephone system for serving one or more geo(cid:173)
`graphic areas formed of a plurality of cellular zones, the 45
`cellular radiotelephone unit comprising:
`receiving means for receiving radio signals transmit(cid:173)
`ted over a reverse radio channel;
`broadcasting means for broadcasting radio signals to
`be transmitted over a forward radio channel;
`measuring means, coupled to the receiving means, for
`measuring the strength of the said signals received
`by the receiving means;
`alarming means for alarming at least the user of the
`cellular radiotelephone unit in response to a detec- 55
`tion of a signal strength value measured by the
`measuring means at or below a first predetermined
`value after a communication link with a second
`party using the forward and reverse radio channels
`is established; and
`control means for controlling the broadcasting means
`to terminate broadcasting radio signals over the
`forward radio channel in response to a detection of
`a signal strength value measured by the measuring
`means at or below a second predetermined value, 65
`not greater than the frrst predetermined value,
`the receiving means continuing to receive radio sig(cid:173)
`nals transmitted over the reverse radio channel
`
`60
`
`6
`after termination of signal broadcast over the for(cid:173)
`ward radio channel.
`11. The cellular radiotelephone unit of claim 10
`wherein the alarming means comprises means for gener(cid:173)
`ating sounds and a related sound signal.
`12. The cellular radiotelephone unit of claim 11 fur(cid:173)
`ther comprising means for broadcasting the generated
`sound signal over the communication link with the
`second party.
`13. The cellular radiotelephone unit of claim 11
`wherein the sound generating means comprises speech
`synthesis means for synthesizing predetermined speech
`patterns.
`14. The cellular radiotelephone unit of claim 10
`wherein the alarming means comprises a visual display
`unit.
`15. The cellular radiotelephone unit of claim 10
`wherein the first predetermined value of signal strength
`measured by the measuring means is equal to the second
`predetermined value of signal strength and the control
`means controls the broadcasting means to terminate
`radio signal broadcast after the signal strength value is
`at or below the first or second predetermined value and
`after the alarming means alarms the user of the unit.
`16. The cellular radiotelephone unit of claim 10
`wherein the first predetermined value of signal strength
`is greater than the second predetermined value of signal
`strength.
`17. A cellular radiotelephone unit of use in a cellular
`radiotelephone system serving one or more geographic
`areas formed of a plurality of cellular zones, the cellular
`radiotelephone unit comprising:
`receiving means for receiving radio signals transmit(cid:173)
`ted over a reverse radio channel;
`broadcasting means for broadcasting signals to be
`transmitted over a forward radio channel;
`measuring means, coupled to the receiving means, for
`measuring the strength of the signals received by
`the receiving means;
`sound generating means for generating sounds and a
`related sound signal;
`means for providing the sound signal generated by
`the sound generating means to the broadcasting
`means so that the sounds are transmitted to a sec(cid:173)
`ond party connected to the user of the unit over a
`communication link using the forward and reverse
`radio channels in response to the detection of a
`signal strength value measured by the measuring
`means at or below a first predetermined value after
`the communication link is established; and
`controlling means for controlling the broadcasting
`means to terminate broadcasting radio signals over
`the forward radio channel in response to the detec(cid:173)
`tion of a signal strength value measured by the
`measuring means at or below a second predeter(cid:173)
`mined value which is not greater than the first
`predetermined value after transmitting the sounds
`to the second party.
`18. The cellular radiotelephone unit of claim 17
`wherein the sound generating means comprises speech
`synthesis means for synthesizing predetermined speech
`patterns.
`19. The cellular radiotelephone unit of claim 17 fur(cid:173)
`ther comprising display means for providing a visual
`display indicating the return to a signal strength value
`above the frrst predetermined value after the signal
`strength value measured by the measuring means is at or
`below the frrst predetermined value.
`
`25
`
`30
`
`50
`
`Kyocera PX 1014_7
`
`

`

`4,996,715
`
`7
`20. The cellular radiotelephone unit of claim 17
`wherein the first predetermined value of signal strength
`is greater than the second predetermined value of signal
`strength.
`21. A method for alarming a user and a second party S
`connected together over a radio communication link,
`the method for use in a cellular radiotelephone unit, the
`method comprising the steps of:
`receiving radio signals transmitted over a control
`radio and a speech radio channel;
`broadcasting radio signals to be transmitted over the
`speech radio channel;
`measuring the strength of the received radio signals;
`providing sounds and a related sound signal, the re- -
`lated sound signal being transmitted to the second 15
`party in response to the detection of a signal
`strength value below a first predetermined value
`after the communication link using the speech
`radio channel is established;
`
`8
`controlling the broadcasting means to terminate
`broadcasting the radio signals and the receiving
`means to receive signals transmitted over the con(cid:173)
`trol radio channel in stead of the speech radio chan(cid:173)
`nel in response to the detection of a signal strength
`value at or below a second predetermined value
`after transmitting the related sound signals to the
`second party.
`22. The method of claim 21 further comprising the
`10 step of
`visually displaying an indication when the received
`signal strength returns to a level above the first
`predetermined value.
`23. The method of claim 21 wherein the sounds and
`related sound signals comprise synthesized speech.
`24. The method of claim 21 wherein the first prede(cid:173)
`termined value of signal strength is greater than the
`second predetermined value of signal strength.
`• * • * •
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`60
`
`65
`
`Kyocera PX 1014_8
`
`