US005428671A
`United States Patent 19
`5,428,671
`(11] Patent Number:
`Dykeset al.
`\
`[45] Date of Patent:
`Jun. 27, 1995
`
`
`UNOACT
`
`[75]
`
`[56]
`
`
`
`i
`
`[54] MODEM FOR TIGHT COUPLING BETWEEN
`A COMPUTER AND A CELLULAR
`TELEERONE
`Inventors: Don A. Dykes, Houston; Robin T.
`Castell, Spring; Andrew C. Clark,
`Houston; Paul E, Nagel, The
`Woodlands; Huyen B. Tran,
`Houston; Randall L. Jones, Plano:
`Ronald L. Baldridge, Carrollton,all
`of Tex.
`[73] Assignee: Compaq Computer Corporation,
`Houston, Tex.
`[21] Appl. No.: 973,625
`.
`,
`[22] Filed:
`Noy. 9, 1992
`(50) Wee CAS escseepsee HO4M 11/00
`[52] US. Ch. cessessecscscseccsseneeeee
`.. 379/93; 379/97;
`379/58; 379/59; 379/355
`[58] Field of Search ............:.:.00+0-+ 379/93, 96, 97, 98,
`379/58, 59, 60, 61, 62, 63, 355; 375/8, 121,9
`:
`References Cited
`U.S. PATENT DOCUMENTS
`Re. 34,034
`8/1992 O'Sullivan .......ssseneeeees 379/59
`4,012,596
`3/1977 West, Jr. et al.
`4,568,800 2/1986 Orikasa ........
`4,658,096 4/1987 West, Jr. et al.
`4,680,787 7/1987
`.. 379/63
`4,697,281 9/1987
`Sahbekedanoreseniiannicenie 379/59
`4,718,080
`1/1988
`Ss
`senor
`3T9/59
`4,737,975 4/1988
`isiGeassGobalauaonpaccuscssbavs case 379/58
`4,732,949
`6/1988
`_
`
`4,759,059
`7/1988
`iba
`wo 379/161
`4,775,997 10/1988 West, Jr. et abs
`sees 379/58
`
`4,837,800 6/1989 Freeburgetal. ...
`. 379/59
`6/1989 Takahashi et al.
`..
`ses 379/98
`4,837,812
`7/1989 Hathcocket al.
`.. 379/58
`4,852,146
`
`
`.- 379/98
`4,868,863
`9/1989 Hartley et al.
`.
`eee
`seers 379/33
`4,887,290 12/1989 Dopetal.
`sseere 379/59
`4,890,315 12/1989 Bendixen etal.
`
`
`vense 379/60
`4,912,756 3/1990 Hop cesssesone
`ay 379/59
`4,972,457 11/1990 O'Sullivan-palainedanin
`4,980,910 12/1990 Oba et al......
`wee 379/354
`4,991,197
`2/1991 Morris.........
`wee 379/58
`
`seve 379/63
`5,127,041
`6/1992 O'Sullivan. ......
`5,131,019 7/1992 Sheffer et al. o....cccccccee 379/39
`
`7/1992 Hochfield et al. os... 379/98
`5,134,648
`9/1993 SaintOn -.-cecsecorsecessesereeee 379/93
`5,249,218
`FOREIGN PATENT DOCUMENTS
`459279
`5/1991 European Pat. Off csccsecesn 379/58
`504007 9/1992 European Pat. Off.
`.
`WO92/10047 6/1992 Finland .
`sennuarabiascesoLTOR
`8/1986 United Kingdom.
`. 379/59
`2170977
`
`6/1989 WIPO ..
`WO8905553
`.. 379/58
`
`5/1991 WIPO .oeeecceccccsescsseseeessseseseetes 379/58
`WO91/07044
`OTHER PUBLICATIONS
`Installation and User Instructions for THE Portable
`Cellular Connection TM, Motorola, Inc. (1992).
`The Go Anywhere Phone, Motorola, Inc. (1987).
`CP 3000, Uniden Corporation of America (1988).
`CDL 410 Features, OKI Telecom (Sep. 1986).
`“Features and Benefits,” Motorola, Inc. (1988).
`(List continued on next page.)
`an
`.
`.
`Primary Examiner—Curtis Kuntz
`Assistant Examiner—Jason Chan
`Attorney, Agent, or Firm—Pravel, Hewitt, Kimball &
`Krieger
`.
`
`ABSTRACT
`[57]
`A modem which includes connections for both land
`lines and a cellular phone. The modem contains high
`and low level routines that allow it to perform standard
`AT commandsrationally when connected to a cellular
`phone, and further perform additional AT commands
`that access cellular specific features. An applications
`software program in a computer connected to the
`modem can provide a numberof options for determin-
`ing whether to use the land line or the cellular phone
`when both are connected. First, it can default to the
`land line and only use the cellular phoneif the land line
`is not available. Alternatively, it can first use the cellu-
`lar phone and only use thelandlineif the cellular phone
`signal strength is not sufficient. Further, cellular file
`transfer operations can be abortedif the remaining bat-
`tery life in the cellular phoneis insufficient to reliably
`complete the transfer.
`
`
`
`
`
`19 Claims, 7 Drawing Sheets
`
`UNIFIED 1004
`
`UNIFIED 1004
`
`

`

`5,428,671
`Page 2
`
`OTHER PUBLICATIONS
`
`Spectrum Cellular and Dacom Systems Sign Bridge
`Manufacturing and Distribution Agreement for United
`Kingdom, Press Release dated Jan. 3, 1988, Spectrum
`Cellular Corporation.
`Spectrum Cellular Launches Portable Office with the
`Introduction of its LapPak Cellular Workstation, Press
`Release, Feb. 8, 1989, Spectrum Cellular Corporation.
`Spectrum and Telular Jointly Announce Signing of
`‘Two Contracts and Agree to Collaborate on New
`Products, Press Release, Dec. 6, 1988, Spectrum Cellu-
`lar Corporation.
`Spectrum Cellular Announces Expanded Product Line
`Offering Additional Compatibility for its Bridge Cel-
`lualr Modem, Press Release, Dec. 13, 1988, Spectrum
`Celluiar Corporation.
`P
`Case Histories in Cellular Data Communications, Spec-
`trum Cellular 1988.
`Peter Shikli, Solving Data Communications Problems
`with the Cellular Network, PICO Jan. 1988, pp. 14-17.
`HazCom One 1™, Spectrum Cellular.
`Stockholder Relations, Spectrum Cellular.
`Ameritech Mobile Communications Announces Mobil
`Access Data Service Utilizing Spectrum’s Bridge and
`Span Cellular Modems, Press Release, Feb. 17, 1987,
`Spectrum Cellular.
`Spectrum Cellular and Omnitel Announce Joint Devel-
`opmentof First Internal Laptop Cellular Modem, Press
`Release, Aug. 24, 1987, Spectrum Cellular.
`Tom Steinert-Threlkeld, Ringing a new era for pay
`Phones, The Dallas Morning News.
`
`Robert C. Adair, Cellular & Data: Coming on Strong,
`‘Cellular Business Jul. 1987, pp. 34-35.
`Spectrum Cellular: The First Name in Cellular Data
`Communication, The Only Name You Need to Know.
`Selling Cellular Data Communications Applications,
`Spectrum Cellular Corporation.
`Compaq Apache Modem Board Level Design Specifi-
`cation, p. 12.
`Toshiba Modem Boasts Wireless Transmission, Jun. 18,
`1990.
`Networking, Infoworld, Feb. 19, 1990 pp. 31, 39.
`Press Kit, Intelligence Technology Corporation, Nov.
`12, 1990.
`Hardware, Infoworld, Feb. 12, 1990, p. 23.
`GRiD PowerTek Debut Cellular/Laptop Combination,
`Feb. 26, 1990, p. 19.
`GRiD Portable Cellular Workstation Technical Speci-
`fications, PowerTek Industries, Inc.
`Toshiba Modems, May 1990, Toshiba America Infor-
`mation Systems, Inc.
`The Cellular Handbook, Microcom, Inc. 1990.
`MNP Cellular Modems, Microcom Systems, Inc. 1990.
`Microcom Announces New Cellular Family, Press Re-
`lease, Jun. 26, 1990, Microcom.
`Michael R. Zimmerman, Microcom Unveils Cellular
`Modems for Laptop Users, PC Week, Jun. 25, 1990.
`Microcom Networking Protocol (MNP), A Brief Tech-
`nical Overview, Microcom, Inc. 1990.
`Celjack TM Technical Specification, Telular,
`1989,
`,
`Compaq Mozart Modem Specification Rev. CX, pp. 15,
`61.
`
`Inc.,
`
`

`

`5
`
`428,671
`
`si3
`
`June 27, 1995
`
`Sheet 1 of 7
`
`U.S. Patent @E°3Sd
`
`WE°Sid
`
`

`

`5
`
`428,671
`
`June 27, 1995
`
`U.S. Patent GI°3id
`
`Sheet 2 of 7
`
`OE°DId
`
`
`

`

`US.
`
`Patent
`
`June 27, 1995
`
`Sheet 3 of 7
`
`5,428,671
`
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`

`

`U.S. Patent
`
`June 27, 1995
`
`Sheet 4 of 7
`
`5,428,671
`
`LAPTOP COMPUTER
`
`COMMUNICATION
`
` 300
`
`ROUTINES
`
`AT COMMANDS
`
`302
`
`MODEM HIGH
`LEVEL
`
`ROUTINES
`
`RNA
`
`— L
`PRIMITIVES
`
`308
`
`CELLULAR
`PRIMITIVES
`
`
`
`Sf ||VENDORNVENDOR’
`
`PRIMITIVES
`
`
`
`DAA
`
`DAA}
`
`DAA
`
`CELLULAR
`
`|---| CELLULAR
`
`PRIMITIVES
`
`PRIMITIVES
`
`PRIMITIVES
`
`PRIMITIVES
`
`FIG. 5
`
`

`

`U.S. Patent
`
`June 27, 1995
`
`5,428,671
`
`CELLULAR
`
`RINGING
`
`OR IN USE?
`
`AND TRANSMITVIA TXA Sheet 5 of 7
`
`GENERATE DTMF TONES
`
`END DTMF TONES TO
`
`DAA VIA DATA PUMP OR
`
`PULSE UNTIL DIAL
`
`MODIFIER OR DONE
`
`REMAINING DIAL
`
`MODIFIER AND
`
`SIGNAL ELEMENT
`
`OPERATIONS
`
`TRANSMIT SIGNAL
`
`ELEMENTSTO FIRST
`
`MODIFIER OR END OF
`
`COMMAND VIA
`
`CELLULAR BUS
`
`TRANSMIT
`
`SEND VIA
`
`CELLULAR BUS
`
`CAN USE
`
`CELLULAR'S DTMF
`
`GENERATOR?
`
`PERFORMDIAL
`
`MODIFIERS &
`
`GENERATE DTMF
`
`TONESIN DATA PUMP
`
`PERFORM DIAL
`
`MODIFIERS & TRANSMIT
`
`COMMAND TO
`
`VIA CELLULAR BUS
`
`

`

`U.S. Patent
`
`June 27, 1995
`
`Sheet 6 of 7
`
`5,428,671
`
`
`FILE_XFER mn
`
`USING
`
`CELLULAR
`
`PHONE?
`
`FIG. 5
`
`
`GET BATTERY
`
`LIFE LEFT
`
`CALCULATE
`
`UNCOMPRESSED
`
`TRANSMISSION TIME
`
`BATTERY STRONG
`
`ENOUGHTO COMPLETE
`
`TRANSMISSION?
`
`CALCULATE APPROX.
`
`
`
`
`TRANSMISSION TIME
`
`COMPRESSED
`
`
`
`
`
`UNCOMPRESSED
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`ENOUGH TO COMPLETE
`
`COMPRESSED
`
`TRANSMISSION?
`
`TRANSMIT
`
`FILE
`
`ATTERY STRON
`
`
`COMPRESS FILE
`
`
`RETURN
`
`
`
`
`
`
`
`AND TRANSMIT
`
`516
`
`

`

`U.S. Patent
`
`June 27, 1995
`
`Sheet 7 of 7
`
`5,428,671
`
`LAND LINE
`
`
`
`
`FIG. 7
`
` ALTERNATE\700
`
`
`
`
`CONNECTVIA
`
`CELLULAR
`
`CONNECTVIA
`
` CONNECT 3
`AVAILABLE?
`
`
`LAND LINE 702
` 704
`
`
`
`
`CONNECT
`
`MAKE CONNECTION
`
`
`OVER CELLULAR
`
`DETERMINE
`
`CELLULAR SIGNAL
`
`STRENGTH
`
`FIG. 6
`
`
`
`THRESHOLD? DISCONNECT
`
`CELLULAR AND
`
`CONNECT OVER
`
`LAND LINE
`
`

`

`1
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`5,428,671
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`to communicate where normal phone connections are
`not available, such as from a car, bus, or train.
`Although standardized within a single country,tele-
`phonesystems around the world are generally nonstan-
`dard, and different hardware is required to connect to
`these various systems. Thus, a modem configured to
`connect to one country’s phone system would generally
`not be suitable for connection to another’s. The physical
`connection to a particular national phone system is
`made through what is known as a data access arrange-
`ment, or DAA. Eachparticular phone system will have
`its own associated DAA. Typically, modems are con-
`structed with a DAA built in. That, however, means
`that a modem suitable for one country would not be
`able to connect to another country’s phone system, or
`would at least require an external DAA.
`With portable, laptop, and notebook computers, the
`problem ofthe different DAA’s required for each coun-
`try becomes even more apparent. One would not wish
`to buy a notebookor laptop with a built-in modem that
`could not be easily modified for use in another country.
`An international traveler might never be sure to which
`country’s phone system he would primarily wish to
`connect. For example, if he lived in the U.S., he would
`want his laptop’s modem to be suitable for directly
`connecting to the U.S.’ phone system. But if he moved
`to Germany, he would wish his laptop’s modem to be
`suitable for directly connecting to the German phone
`system. But further, if our hypothetical businessman,
`living in the U.S., traveled to Germany, he would want
`to be able to connect his laptop into the German phone
`system even though his laptop’s modem is internally
`configured for connection to the U.S. phone system. To
`this end, external DAA’s have been used, with one
`phone system handled by default and others handled by
`the appropriate external DAA.
`For a computer user in a car, bus, or train, another
`recent technological development provides possibilities
`for laptop and notebook modem communications. With
`the recent expansion of cellular telephone systems, a
`cellular telephone has become a very common, and
`very portable, item. Not surprisingly, crude attempts at
`a marriage between cellular telephone technology and
`modem technology have been made using laptop and
`notebook computers and cellular phones. By connect-
`ing a laptop to a cellular phone, one can access a tele-
`phone network in generally the same wayas by directly
`hooking to a telephone wall outlet, or via a “landline.”
`
`MODEM FOR TIGHT COUPLING BETWEEN A
`COMPUTER AND A CELLULAR TELEPHONE
`
`BACKGROUND OF THE INVENTION
`1. Fieid of the Invention
`This invention relates to a modem designed to con-
`nect a computer with a cellular telephone. More specifi-
`cally, it relates to a modem with firmware and hard-
`ware designed to provide a tightly integrated coupling
`of functions between the computer and the cellular
`telephone, such that the computer can control features
`of the cellular telephone and inquire aboutcellular tele-
`phone conditions, and can respond accordingly.
`2. Description of the Related Art
`In the year 1948, a simple device was invented that
`was to have a profound impact on modern life. That
`device was the electronic transistor. It was the transis-
`tor that
`first made computers technically practical.
`These first computers were behemoths—centralized
`machines servicing a large numberofusers and a large
`number of tasks. While the economic impact of these
`mainframe systems was tremendous, it was not until the
`subsequent developmentof the microprocessor, and the
`attendant development of the personal computer, that
`computer technology directly impacted the lives of the
`modem consumer and small businessman.
`Whenthe personal computer market exploded in the
`1980's,it filled needs very different from those filled by
`the mainframe computer. Personal computers were
`used to perform individual, isolated tasks without com-
`munication with other computers except perhaps
`through manual exchange of floppy disks. The main-
`frame computerstill served the requirements ofcentral-
`ized data access and coordination among a large num-
`ber of users.
`But as the personal computer market developed, the
`advantages and possibilities of communicating among
`these machines becameapparent. Oneof the methods of
`communication that rose to the forefront was modem
`technology. By connecting modems to their personal
`computers, users could directly transfer data between
`and communicate in realtime with mainframes and
`other personal computers. For example, bulletin board
`systems have now become very popular, allowing a
`large numberofusers to remotely upload and download
`free software, exchange information, and engage in
`online forums. With modems’ rising speeds, increased
`standardization, and expanding uses, one is now hard
`pressed to find a personal computer system that does
`not use a modem.
`While intercommunication between personal com-
`puters and mainframes was on therise, another develop-
`ment was to have an impact on the need for communi-
`cating with distant systems. Personal computers were
`becoming smaller. From the original large under-the-
`desk machines, desktop machines evolved, then tran-
`sportables, and finally laptop and notebook computers.
`These laptops and notebooks are typically very mobile,
`easily traveling from city to city, state to state, and even
`country to country. But the advantage of portability
`itself presents a problem: while stationary machines can
`be conveniently connected to communication networks
`via a telephoneline, laptop users might wish to establish
`communication links from countries with which their
`laptop’s modemsare not compatible, or they might wish
`
`Using a cellular phone forestablishing a modem com-
`munications link does present attendant problems, how-
`ever. Certain standards have evolved for communica-
`tions between a computer and its attached modem.
`These physical links are generally made througha serial
`or parallel communications port or through the host
`computer bus, and logically certain commandsare sent
`to the modem, which returns certain responses. The de
`facto standard for these commands is the Hayes Mi-
`crocomputer Products “AT” command set. This com-
`mand set is well known in the art, and includes such
`commands as the ATDTn command, which instructs
`the modem to dial the number “n” and the ATH com-
`mand which instructs the modem to hang up thetele-
`phone. Unfortunately, these commands were designed
`with land line connections in mind, and certain aspects
`of cellular telephone systems do not lend themselves
`toward activation or use through these AT commands.
`For example, commandssuch as “take the phone off the
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`hook” makelittle sense in the cellular world, as the
`cellular phoneis either attempting to access its network
`or it is not-it does not go “off hook” before it does,
`Thus, the standardized AT commandsetis not always a
`perfect fit with cellular phones, and laptop software
`that uses the AT command set will not necessarily re-
`ceive expected results from attempting certain com-
`mands. Previous attempts at combining a cellular phone
`with a modem have required the use of special com-
`mand sequences, so that it was difficult to switch back
`and forth between the cellular phone anda landline.
`Such special sequences also led to problemsin achiev-
`ing seamless integration of high level applications. For
`example, a user’s computerized phone directory would
`often require complete reentry to place the needed
`special command sequences within the numbers to be
`dialed.
`It would be desirable to use a conventional land line
`commandset, such as the AT commands, in a way such
`that it was performed consistently whether a cellular
`telephone network or a land line system was used. It
`would also be desirable to provide access to various
`features of cellular phones not generally available in a
`land line.
`
`4
`If, however, the cellular phoneis not capable of being
`directed to generate DTMF tones, the modem gener-
`ates DTMFtones in its internal data pump andtransmits
`those tones overthe audio path to the cellular phone to
`perform additional functions after the connection to the
`called number is made.
`Other standard AT commandsalso behave predict-
`ably when used with a cellular phone attached to a
`modem constructed according to the invention. For
`example, the ATA (answer) and ATH (hang up) com-
`mands both behave predictably, even though land line
`operations do notreadily translate to the cellular phone
`model.
`Further, the AT command set of a modem con-
`structed according to the invention is extended to pro-
`vide control of cellular specific features that would be
`useful to the host computer and to provide access to
`cellular information. For example, the modem includes
`AT commandsthat return the manufacturer and phone
`number of the cellular phone, that enable and disable
`the cellular phone keypad, that lock and unlock the
`cellular phone, that sets the cellular NAM (numeric
`address module),
`that log time used by the cellular
`phone, that reset the cellular timers, that store and re-
`trieve phone numbers stored in the cellular phone, that
`display data on the cellular phone display, that deter-
`A modem constructed according to the invention
`mine the cellular battery strength, that return the status
`includes connections for both land lines and a cellular
`of certain cellular phone features (i.e., roam, in use, call
`phone. Communication software in the host computer
`forwarding, locked, system type), that select the appro-
`sends normal AT command codes to the modem, which
`priate cellular system, that return the signal strength
`then selectively performs low level primitives, selected
`andset the signal strength threshold, that set the cellular
`according to whether a communications link is to be
`automatic shutoff time, and that permit setting of the
`established or has been established through a land line
`speaker and ringer volumes. Further, an AT command
`or throughacellular phone.
`is included that permits the host computerto specify the
`35
`In a modem built according to the invention, the
`modelof cellular phone that would be connected to the
`modem firmware provides a seamless control link be-
`modem constructed according to the invention.
`tween the host computer andthecellular phone. Specif-
`In a modem built accordingto the invention, applica-
`ically, AT commands normally sent to the modem for
`tions software in the computer performs a special se-
`controlling land lines behave predictably when the
`quence when it is desired to transfer a file over the
`modem is instead controlling the cellular phone.
`cellular phone. First, the high level computer queries
`An example of an AT command whichis moresuited
`the modem through AT commands to determine the
`towards landlines, but behaves rationally in the modem
`strength of the cellular battery. The modem determines
`constructed according to the invention, is the AT dial
`the cellular battery strength by communicating over the
`command, or ATDT. In a modem according to the
`cellular phone’s communications bus, and the modem
`invention, when the computer applications software
`then returns the results of these inquiries as a response
`sends a dial command to the modem, and the modem
`to the AT command requesting the battery strength.
`determines that a cellular phone is connected,
`the
`The computer application software determines, consid-
`modem first directs the cellular phone to receive the
`ering the current bits per second rate and the length of
`numbers specified by the dial command upto thefirst
`the file to be transferred, whether thecellular battery is
`delaying dial modifier character or the endofthestring.
`too weak to completethe file transfer. If the battery is
`The modem according to the invention instructs the
`strong enough,thefile is transferred normally, with the
`cellular phone to store these numbers by sending com-
`computer sending the file to the modem, which sends
`mands to the cellular phone through the cellular
`the data to the cellular phone.Ifthe battery is too weak,
`phone’s communication bus, as opposed to sending an
`the high level application software determines if the
`analogsignal to the cellular phone via the modem’s data
`battery is strong enough to send file if the file is first
`pump. After the numberto be dialed has been transmit-
`compressed. If the battery is still too weak, an ERROR
`ted to the cellular phone through its communications
`is returned to the user. Otherwise thefile is compressed
`and transmitted.
`bus, the modem then sends a SEND commandto the
`cellular phone on that same communications bus. This
`Further applications software in the computer con-
`instructs the cellular phone to dial the previously en-
`nected to the device according to the invention first
`tered number. After dialing that number, if the cellular
`attempts to establish a connection via a Jand line con-
`phoneis capable of generating its own DTMFcodes
`nected to the modem.If that land line is not working
`and can be directed to generate those codes throughits
`properly, or the connection cannot otherwise be made,
`cellular communications bus, the modem directs the
`then the applications software then instructs the modem
`cellular phone by commandsoverthe cellular commu-
`to initiate the connection through an attached cellular
`nications bus to generate the DTMF tones and appro-
`phone.
`priate pauses that correspond to the numbers including
`Application software in the computer connected to
`and following thefirst delaying dial modifier character.
`the device according to the invention can also first
`
`SUMMARY OF THE INVENTION
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`attempt to establish a connection via the cellular phone,
`and if the cellular phone signal strengthis insufficient,
`disconnecting the cellular phone connection and estab-
`lishing a connection over the Jandline.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`A better understanding of the present invention can
`be obtained when the following detailed description of
`the preferred embodimentis considered in conjunction
`with the following drawings, in which:
`FIGS. 1A-D show a laptop computer with a modem
`according to the invention connected for operation in
`various configurations.
`FIG. 2 showsa block diagram of the hardware in a
`modem designed to perform the methods according to
`the invention.
`FIG. 3 shows a block diagram of the sequences used
`to control the modem of FIG. 2, those sequences de-
`signed to implement the methods according to the in-
`vention.
`FIG. 4 shows a flowchart of operation of the dial
`command as executed by the modem of FIG. 2 in accor-
`dance with the methods of the invention.
`FIG.5 showsa file transfer sequence as executed by
`the computer and modem of FIGS. 1A-1D according
`to the methodsof the invention.
`FIG. 6 shows a cellular versus land line selection
`sequence as executed by the computer and modem of
`FIGS. 1A-1D according to the methods of the inven-
`tion.
`FIG. 7 shows a flowchart of an alternative connect
`sequencefor selecting between theland line and cellular
`telephone based upon the available signal strength of
`the cellular telephone.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`Turning now to the drawings, FIGS. 1A-D show a
`laptop computer 10 with a modem 12 constructed ac-
`cording to the invention connected for operation in a
`variety of configurations. The modem 12 is integrated
`into the laptop computer 10, and the modem 12 has two
`external jacks for connection to a variety of devices.
`Thefirst of these jacks is an RJ11 type jack 14, and the
`second is an RJ45 type jack 16. Of course, these physi-
`cal jacks are exemplary only, and other types of jacks
`could be used. Further, the modem 12 is preferably, but
`not necessarily, integrated into the laptop computer 10,
`and the laptop computer 10 could be a type of computer
`other than a laptop. For example, a desktop system
`would also benefit from being connected to the modem
`12 constructed according to the invention.
`In FIG. 1A, the laptop computer 10 and the modem
`12 are connected by way of the RJ11 type jack 14 and
`a cable 20 to a telephone wall outlet 18, as one would
`find in any typical home. The RJ45 type jack 16is left
`unconnected. This configuration is analogous to a com-
`puter with an integrated modem connected to a tele-
`phone wall outlet.
`FIG. 1B again shows the laptop computer 10, but in
`this configuration the modem 12 is connected to a cellu-
`lar phone 22 via the RJ45 type jack 16 by an interface
`cable 20. In this configuration, the RJ11 type jack 14is
`left unconnected. The cellular phone 22 may have, for
`example, a DTMF generator 21, a cellular keypad 23,
`cellular timers 25, memory 27, a display 29, and a bat-
`tery 31. Some cellular phones have these features, while
`others do not, but they are well known to those skilled
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`in the art of cellular phone manufacture. The DTMF
`generator 21,
`the cellular keypad 23, the timers 25,
`memory 27, and the display 29 are all typically inter-
`nally controlled by circuitry in a cellular phone.
`FIG. 1C showsthe laptop computer 10 and modem
`12 configured for operation in a foreign country. In
`FIG. 1C, the laptop computer 10 is connected via the
`RJ45 type jack 16 to a telephone wall outlet 18, but in
`this configuration an external DAA 24 provides the
`circuitry necessary to adapt to the foreign telephone
`system. An advantage of the modem 12 constructed
`according to the inventionis that it can be easily modi-
`fied to changeits internal, “native” country. Thatis, the
`external DAA 24 is only needed if the modem 12 has
`not been configured internally for the country to which
`one is attempting to connect the laptop computer 10.
`Thus, if the modem 12is internally configured for the
`U.S. telephone system, if one is in the U.S., one need ~
`only connect the system as shown in FIG. 1A in order
`to communicate with the telephone system. Only if one
`goes to another country, say Germany, would one need
`the external DAA 24 as shown in FIG. 1C.
`But if the user then moves to Germany, that user
`could easily have the modem 12 modified such that the
`German telephone system becomes its “native” phone
`system. This would be done by a technician simply
`switching out an internal DAA, which will be described
`later. Then, while in Germany, the user configures the
`laptop computer 10 as shown in FIG. 1A for communi-
`cations with the German telephone system. When the
`user visits the U.S., the user would then use the external
`DAA 24, which is then specifically designed for the
`U.S.
`FIG. 1D showsa furtherpossible configuration ofthe
`laptop computer 10 with the modem 12 constructed
`according to the invention. In FIG. 1D,
`the laptop
`computer 10 is connected to both the cellular phone 22
`and the telephone wall outlet 18, which is here a tele-
`phone jack for the native telephone system of the
`modem 12. In this configuration, the laptop computer
`10 is connected to the cellular phone 22 via the RJ45
`type jack 16 and is connected to the native phone sys-
`tem via the RJ11 type jack 14 and the telephone wall
`outlet 18. As will be seen, an advantage of the modem
`12 constructed according to the inventionis that it can
`internally switch between communications with the
`cellular phone 22 and the telephone wall outlet 18.
`
`Logical Blocks of the Modem 12
`FIG. 2 showsa logical block diagram of the various
`elements of the modem 12 constructed according to the
`invention. The laptop computer 10 physically contains
`the modem 12 and connects via an internal connector to
`a UART/support chip 100. The UART/support chip
`100 typically connects to the host bus of the laptop
`computer 10, for example an EISA or ISA bus, al-
`though it could be any type of typical communications
`bus. The UART/support chip 100 then appears as a
`universal asynchronousreceiver transmitter (UART) to
`the laptop computer 10. The UART/support chip 100
`connects to, among otherthings, a microcontroller 102
`by both serial and parallel buses. The UART/support
`chip 100 provides a variety of functions to the modem
`12, including communications to the laptop computer
`10, clock controls, configurable registers, and power
`down control for the microcontroller 102. The UART-
`/support chip 100 is typically an application specific
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`integrated circuit, but could instead be constructed of
`discrete components.
`The microcontroller 102 is typically an embedded
`controller, and in the preferred embodimentis a 68302
`integrated multiprotocol processor, manufactured by
`Motorola Incorporated. The microcontroller 102 com-
`municates with a data pump 104 by both serial and
`parallel buses. The data pump 104 is typically a modem
`data pumpchip set supporting the various protocols of
`modem communication, including V.32bis protocol and
`fax protocols. In the preferred embodiment, the data
`pump 104 is a WE ® DSP16A-V32FB-LTV.32bis plus
`FAX Data Pump Chip Set, sold by AT&T Microelec-
`tronics. This chip set includes a digital signal processor
`(DSP) support chip 106, a DSP 108, and a coder-
`decoder (CODEC) 110. This chip set is interconnected
`according to AT&T specifications and provides the
`typical data pumpfeatures of control, analog-digital and
`digital-analog conversion,digital signal processing, and
`interfacing.
`The microcontroller 102 communicates with the data
`pump 104 by both serial and parallel buses. The serial
`bus is used to transmit and receive data that will become
`the transmitted and received modem data, while the
`parallel bus is used to control and configure various
`features within the data pump 104. These features are
`controlled through the DSP support chip 106. The data
`pump 104 converts the digital serial data provided by
`the microcontroller 102 into the appropriate analog
`format. This is typically done by the DSP 108, which
`then transmits and receives the data via the CODEC
`110.
`The CODEC110 connects to the actual external lines
`through analog transmit and receive signals, TXA and
`RXA.These signals are selectively connected to either
`an internal DAA 112 ora cellular/external DAA inter-
`face 114. The internal DAA is then connected to a
`normal telephone line by the RJ11 type jack 14, while
`the cellular/external DAA interface 114 can be con-
`nected through the RJ45 type jack 16 to the external
`DAA 24 or the cellular phone 22. When connected to
`the cellular phone 22, a number of data lines from the
`microcontroller 102 and UART/support chip 100 form
`a cellular communications bus, whichis a serial, digital
`bus that varies for each make of cellular phone 22.
`Various signals are typically used to interface with
`telephonelines, including the ring indicator signal RI*
`and the off hook control signal OH*. A DAA generates
`and receives these signals, as well as the TXA and RXA
`signals, and converts them into a formatsuitable forthat
`particular country’s two-wire telephone system, or
`whatever type of telephone system to which the DAA
`is connected. Various digital lines, including RI*, OH*,
`a clock line CLK*, and a data line DTA,form a set of
`switched data lines between the cellular/external DAA
`interface 114, the UART/support chip 100,
`the mi-
`crocontroller 102, and the internal DAA 112. In this
`embodiment, the OH*signal line is physically driven by
`the DSP support chip 106. These lines, as well as the
`TXA and RXA lines, can be switched by the microcon-
`troller 102 to connecteither the cellular/external DAA
`interface 114 or the internal DAA 112.
`In operation, the modem 12 according to the inven-
`tion and as logically shown in FIG. 2 is connected in
`one of the configurations shown in FIGS. 1A-D. Thus,
`the RJ45 type jack 16 is connected to either a cellular
`phone 22 or an external DAA 24, which would gener-
`ally be a DAA constructed for operation in a country
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`otherthan that ofthe internal DAA 112. The RJ11 type
`jack 14 is directly connected to the phone system of the
`native country of the modem 12, that native country
`being determined by the country with which the inter-
`nal DAA 112 is compatible. The internal DAA 112 is
`typically a separate physical board inside the laptop
`computer 10 that is directly connected to the modem
`12. If one desired to mov