CA2188790C

CA2188790C - Data communications device to selectively operate as an analog modem, a digital modem, and a terminal adapter

Info

Publication number: CA2188790C
Application number: CA002188790A
Authority: CA
Inventors: Steven R. Blackwell; John Timothy Pearson; Charles C. Fridlin, Iv
Original assignee: Motorola Inc
Current assignee: Motorola Mobility LLC
Priority date: 1995-02-28
Filing date: 1996-01-04
Publication date: 1999-12-21
Anticipated expiration: 2016-01-04
Also published as: EP0761044A4; IL116713A; JP3706631B2; TW295756B; IL116713A0; ZA961601B; WO1996027241A1; CA2188790A1; EP0761044A1; US5671251A; JPH09512978A

Abstract

An apparatus and method for a data commmni-cations device to selectively operate in a plurality of analog and digital modes, including as an analog mo-dem (762), as a digital modem (774), and as a temmi-nal adapter (794). The embodiments provide for a sin-gle, integrated data device to be con-figured and also subsequently reconfigured to provide for data communication over a variety of networks, in-cluding public switched telephone networks and digital networks, including Tl, El and ISDN. The various em-bodiments also provide for signal simulation (370) of the various networks, such that the actual coupled network is transparent to a data temminal transferring information through the data communication device to the network.

Description

~ W096127241 21 88790 ~ s DATA COMMUNICATIONS DEVICE TO SELECTIVELY OPERATE AS AN ANALOG
MODEMr ~ D~GITA~MODEM; AND A TERMINAL ADAPTER.
Field of the Invention This ~ ,), " ~ relates to data communications devices for L,d"a",ission and reception of data including, but not limited to, analog modems, digital modems, terminal adapters, and other analog or digital 10 data communications devices.
Background of the Invention T,d"b~ni"y data and other illfullll " :1 between two or more 15 separate locations is an i,,~,,tSasi,~u~y common occurrence in this ~i, ' ", ~ age~. In the 1970s and through much of the 1980s, a large ~..,t,rltd~e of such data transfers were made using analog modems, which modulate and demodulate digital data onto an analog carrier signal. Modems are a type of data communications device that typically 20 use analog I,a"s",iabi~n media, such as telephone lines.
Modems are classified as low-speed, medium-speed, and high-speed modems. The low-speed modems transfer data at rates between 300 bps (bits per second) and 1200 bps, with medium-speed modems operating at rates in the 2400- 4800 bps range, and with high-speed 25 modems having rates greater than 4800 bps. An analog modem is a data communication device which modulates data and transmits the modulated data as an analog signal, and also receives modulated data as an analog sisnal and demodulates the received data. Most analog modems receive and transmit the modulated data as an analog signal 30 over one twisted pair of wires, coupled to the Public Switched Telephone Network ~PSTN~) through an analog interface circuit. Currently, the fastest high-speed analog modems operate at data transfer rates of d~ulu~illldI~ly 30,000 bps, which some It:lecol"",-Jnications engineers consider to be near a lI,eorc:li,,dl limit of ~Idl)SlllibbiOn rates over most 35 analos telephone lines.

WO 96127241 2 1 8 8 7 9 ~
A variety of desirable r~ )n~, however, such as ~k,...)lo~ i"~
data files from and Lldi~s~ documents t~ vari~us n~tworks,- may require higher speeds of data lldl~SI~liasion than is currently prd~;ti~,aL,le, affordable, or available over most analog telephone lines. Accordingly, 5 many l~lt,cc",ll,l.mication providers have begun to offer and to i"~pl~"~
Yarious digital lldi~a~ ,aion services such as, for example, switched di~ital services, T1 services, E1 ssrvices, and Integrated Services Digital Networks (~ISDN~). Many typical digital cûnl ,~iùns use two such ~wisted pairs~ of wires, one for ~,d,,a,,,;aaiun and the other for reception, 10 coupled to a digital network through a digital interface circuit. A typical T1 ~onnecliùn has a data rate of 1.544 Mbps (megabits per sacond), which is furthertime division ml~ rl~Yed (~TDM~) into digital (not analog) tldl~al"i~aion channels. The T1 cu,~i~e~,tion comprises 24 channels, with each channel referred to as a DS0 having a data rate of 64,000 bps.
15 ISDN systems typically comprise two 64 Kbps ~B~ channels (for voice and data ~Idl~al"iaaion) and one 16 Kbps ~D~ channel (for signalling i"~ and low speed packet data). spq. ;r;. ~ ,s and standards for ISDN, T1, and E1 sarvices are described in numerous CCITT
n~ u"""~ Y, such as Recu."...~l,Jdt;~ll G (forT1, E1), and 20 na~u..""~"Jdli~ I (for ISDN). Other discussions of analog and digital l~lec~-"",unications services may be found in a wide variety of l.'~rel".i~s, such as R. Freeman, Reference ~A^nual for Telecommuni-~tin~ En~ineers. John Wiley & Sons, 1985.
Digital modems and terminal adapters have typically been used to 25 transfer data over such digital lines. Digital modems typically further encode the mnrlll~-~-c~ analog signal from a modem, using digital encoding schemes such as pulse code modulation ("PCM"), to transfer the analog signal over a digital line. Such digital modems would typically ba used when the other (or remote) modem receiving the data is 30 coupled to an analog line and, therefore, cannot receive the purely digital data which could be communicated over a digital line. Terrninal adapters are a type of data communication device designed to transmit and receive digitally encoded data directly from a digital network, without i~lt~ ;lly moduiation of data onto an analog carrier signal or 35 demodulation of an analog carrier signal into digital data.

W096/27241 2 l 8 8 7 9 0 ~ 25 Separate data communication devices such as analog modems, di~ital modems, and terminal adapters, are available and known in the art of modem tel~"""unications. Each such device, however, is typically ;"c~" ,, ' ' o for use in another fommat or mode, as data S communications devices have evolved to be either digital or analog, but not both. For example, in the prior art, an analog modem cannot be used to transmit data on a digital network. Co,,t:spor,ui,,y!~, in the prior art, neither a digital modem nor a temminal adapter could be used to transmit data on an analog ~,d,-~",;~s;un line.
1 û As modern lelecu,,,,,,unications ~Idllai~iùns to digital formats, existing analog mûdems ultimately may be rendered obsolete, wUh a COI~Cu,,, ~ loss of i"~.t"~lt by users in their analog equipment and other ~ 1uyy. In areas where digital network services have become both available and cost-effective to employ, those users that have ~I dl laf~l l tld to digital services may nûn~tl l~ need to communicate with analog networks, and vice-versa. For example, many cu"uord~i~ns may employ digital networks for intemal communications, while continuing to need analog services for external communications, for example, to allow an employee to log in and enter the system from a 2û remote location over the PSTN. In addition, many current analog system users continue to require analog Ircll~ ,lll;~ ,iun devices, but may want to plan for the future by investing in data communications equipment which will be col~ dliL,I~ with both current analog and future digital l,d,~s,,,;~siun schemes.
Current solutions to this cu,,,, ' ~y problem have been to ess~r,~;&l'j build separate analog and digital devices, which may then be illcoil,o,dlt:d into a single housing. For example, Motorola has manufactured various hybrid devices, such as the HMTA 200, which combines a terminal adapter with digital modem functions. Other 3û manufacturers, such as US Robotics, have simply built physically separate "cards~ which sepa,..:~,,y perfomm these i,,cul,,udlil,le digital and analog functions and which separately connect to digital or analog interfaces.
Current solutions to the analog and digital i"-,o",, ~i"'y problem 35 have been ir~ eq~l~tP, however, because such current solutions have .

W0 96/27241 P~
2l 887~0 simply physically combined otherwise separate sets of anaiog and digital hardware into one packag~ having both analog and digital interfaces often with redundant hardware such as ",i~;,u~ ru~ess~ RAM and ROM.
Theneedhasarisen theretore forasingle integrateddata 5 communications device which will provide complet~ analog and digital data l,d"~",ission services heretofore provided by separate i"d~ende,lt, and i"c~", - devices.
Brief Description of the Drawings FIG. 1 is a block diasram which illustrates a prior art use of an analog modem for data transfer.
FIG. 2 is a block diagram which illustrates a prior art use of a digital rnodem for data transfer to an analog modem.
FIG. 3 is a block diagram which illustrates a prior art use of a terminal adaptar for data transfer within digital networks.
FIG. 4 is a block diagram which illustrates a preferred ~",~o.li",er"
of the present invention.
FIG. 5 is a block diagram which illustrates the digital switching ",e. I,a,~;~",:, of the processor of the preferred ~ udi,,,e,,l of the present invention.
FIG. 6 is a block diagram which illustrates the digital multiplexing of the processor of tha preferred e",L,o~i",e"l of thr~ present invention.
FIG. 7 is a flow chart which illustrates the method of the preferred e",~o.li",e"l of the present invention.
FIG. 8 is a block diagram which illustrates a second e",l.udi",t", of the present invention.
FIG. 9 is a block diagram which illustrates a third e"ll,odi",erlt of the prasent invention.
APPENDIX A illustrates a source code program for i",pl~",e"ldli~n of the switching and simulation aspects of the preferred ~",b~di",e"l of the present invention.

2 1 ~ 8 7 9 0 ~ c - 1~S
Description of the Preferred Embodiment FIG. 1 is a block diagram which illustrates a prior art use of an analog modem for data transfer. As shown in FIG. 1, a local temminal 100, such as a computer, is coupled to a local analog modem 102 via transmit line 150 and receive line 151. Such transmit and receive lines 150 and 151, for example, may be part of an RS 232 interface (and cable) typically employed to couple a computer to a modem. The local analog modem 102 is coupled via line 110 to the PSTN 126. The line 110 may be a standard (twisted pair) telephone line which transmits an analog signal. A remote terminal 106, which may also be a computer, is coupled to a remote analog modem 104 via transmit line 161 and receive line 160. The remote analog modem 104 is coupled via line 120 to the PSTN
126. Line 120, like line 110, may also be a standard telephone line. As indicated in FIG. 1, the local terminal 100 and local analog modem 102 are arranged to transfer data, i, ,fur,, ~ and other signals, between a remote terminal 106 having a remote analog modem 104, over the PSTN
126. Data, including i,,~u,,, .~ and command signals, are l,d"~ftlr,t,d between the terminals and their ,~,e~ c analog modems over the various ,t:~,u~.ti~ transmit and receive lines 150, 151, 160, and 161.
Il~fu~ n from the terminal 100 is modulated and otherwise prucessed by the local analog modem 102 to form an analog modem signal to the PSTN 126 over line110. The analog modem signal is then lldll~f~ d to the remote analog modem 106 by the PSTN as an analog signal over line 120. Within the PSTN, the analog modem signal may be converted to a digital signal for l,dns",issiû,1 within the network, and reconverted to an analog modem signal for l,;lns",i~siol, over the analog lines 110 and 12û. The remote analog modem 106 demodulates the received analog modem signal and transmits the demodulated data to the remote terminal over line 160. Il,lu~",dl;on from the remote analog modem 106 may also be lldll~lllill~d to the local analog modem 102 using the same method operating in the opposite or reverse direction.
FIG. 2 is a block diagram which illustrates a prior art use of a digital modem for data transfer. As shown in FIG. 2, a local temminal 100, 35 such as computer, is coupled to a iocal digital modem 222 via transmit WO 96/27241 r~

line 250 and receive line 251. Such transmit and receive lines 250 and 251, for axample, may be part of a digital modem interface (and cable), Cu~ .dldl l_ to the analog RS 232 interface, also typically employed to couple a computer to a digital modem. The local digital modem 222 is coupled via ~igital transmit line 260 and digital receive line 261 to a digital network 228, which is further coupled to the PSTN 126. The di~ital transmit and receive lines 260 and 261 may be standard digital lines, such as T1, E1, or ISDN lines, which transmit a digUal signal. Also as shown in FIG. 2, remote terminal 106, which may also b~ a computer, 1 û is coupled to a remote analog modem 104 via transmit line 161 and receive line 160. As in FIG. 1, the remote analog modem 104 is coupled via line 120 to the PSTN 126 and line 120 may also be a standard analog telephone line. As indicated in FIG. 2, the local terminal 100 and local digital modem 222 are arranged to transfer data and other i"' Illdti~l and signals, between a remote tarminal 106 having a remote modem 104, over the disital network 228 and the PSTN 126. Data, including i~fu~ dt;on and command signals, are llalla~lltld between the terminals and their respective modems over the various transmit and receive lines 250, 251, 160, and 161. I,,fui,,,d~ion from the local temminal 100 is first pruc~a~ed by the local digital modem 222 to form a modulated ânalog signal, which is then further encoded (for example, using a pulse code modulation (PCM) scheme having either a mu-law or an A-law w~ ,andl,,) to form a digital signal ~,d"s",illed to the digital network 228 and further l,d"a",illad to the PSTN 126. The PSTN reconverts the digital signal to a modulated analog signal, which is then lldlla~ d to the remote modem 106 by the PSTN as an analog signal over line 120.
The remote modem 106 demodulates the received modulated analog signal and transmits the demodulated data to the remote terminal over line 160. I,,iur,,,a~iu,~ from the remote modem 106 may also be lldi-all,itl~d to the local digital modem 222 using the same method operating in the opposite or rev~rse direction.
FIG. 3 is a block diagram which illustrates the prior art use of a terminal adapter to transmit data over local and remote digital networks.
As shown in FIG. 3, a local terminal 100, such as computer, is coupled to a local terminal adapter 223 via transmit line 250 and receive line 251.

WO 96/27241 2 1 8 8 7 9 0 ~ I/.L ~ ~ G 125 Such transmit and r~ceive lines 250 and 251, for example, may be part of a terminal adapter interface (and cable), c~ Ja,d~l~ to an analog RS
232 interface, also typically employed to couple a computer to a terminal adapter. The local terminal adapter 223 is coupled via digital transmit line 260 and digital receive line 261 to a digital network 228, which is further coupled to the PSTN 126. As in FIG. 2, the digital transmit and receive lines 260 and 261 may be standard digital lines, such as T1, E1, or ISDN, which transmit a digital signal. As shown in FIG. 3, remote terminal 106, which may also be a computer, is coupled to a remote terminal adapter via transmit line 261 and receive line 260. The temminal adapter 272 is coupled via transmit line 271and receive line 270 to the remote digital network 265. The local digital network 228 is coupled to the remote digital network 265 via the PSTN 126. As indicated in FIG. 3, the local terminal 100 and local terminal adapter 223 are arranged to transfer data and other i"'~ . ", ~ and signals, between a remote terminal 106 having a remote terminal adapter 272, over their ,~.ye.iLiJo digital networks 228 and 265, through the PSTN 126. Not shown in FIG.

3, the local and remote terminal adapters may also be coupled to the same digital network, without an i" ~ve"i"~ PSTN. Data, including i"fu"".~ti.~n and command signals, are lldll~ d between the terminals and their ,~ape~ti~ c terminal adapters over the various transmit and receive lines 250, 251, 260, and 261. Ill'~ llldliùn from the local terminal is formatted or ~,v..esse~l to form a digital signal such as, for example, a DSO format digital signal, which is then lldl~SIIIi~ to the digital network 228, which may be further lldl~s",itl~d to the PSTN 126. The remote digital network 265 receives the digital signal from the PSTN 126, and transmits the digital signal to the remote terminal adapter 272. Not shown in FIG. 3, the remote terminal adapter may alsû be arranged to receive the digital signal directly from the local digital network 228. The remote terminal adapter decodes the received digital signal and transmits the decoded data to the remote terminal over line 260.
I".'ur",dlid~, from the remote terminal 106 may also be lldll~ d to the local terminal 100 using the same method operating in the opposite or reverse direction.

W096/27241 2 1 88 7 90 ~ s ~
FIG. 4 is a block diagram illustrating the preferred 61llbodil~ l of the present invention. As discussed in greater detail below, the data communication device of the preferred ~",l,o(li",e"~ may be sele~ oly configured by the user to operate in any one of a plurality of modes, 5 namely, as an analog modem, as a digital modem, or as a terminal adapter. In addition, after a first operating mode is selected, the data communication device of th~ preferred el,lbudi,,,el,,~ may be reconfisured by the user to operate in a second. third or otherwise different operating mode. As shown in FIG. 4, a data communication device 300 is 10 r~l Irle~bl9 to a terminal 100 to transmit and receive data over the PSTN
126, when coupled to the PSTN 106 through an analog interface circuit 314 (also known as a data access alldl~6111t711l or "DM~), and to transmit and receive data over the digital network 228, when coupled to the digital network 228 through a digital interface circuit 318. As used 15 herein, ~digital network~ or"digital communications network" shall also include digital c~r",e.,~;~ns or interfaces to the central office of the public switched network, including through T1 or E1 interfaces, in addition to digital networks such as ISDN. The user of the data communications device 300 may select the type of operating mode (as an analog modem, 20 as a digital modem, or as a terminal adapter), through a plurality of user command signals ~ntered via the user interface 3û1 coupled to the processor 370. The user may initially select a particular operating mode, and may subsequently change or revise the operating mode. For example, a user may initially couple the data communication deYice 300 25 to a first communications network such as the PSTN 126, and c~l,t,a,uor,.li,,u~ly select the operating mode of the device to be as an analog modem, through user command signals entered through the user interface 3û1. S~hse~ently, the user may haYe capability to access a second communications network, such as a T1, ISDN or other digital 30 nt,t..olki"g interface or capability installed at the user facility. The user may then reconfigure the data communication device 300, through other user command signals (from the plurality of user command signals) entered through the user interface 301, to operate in various digital operating modes, such operating as a digital modem or operating as a 35 terminal adapter.

~O 96/27241 2 ~ 8 8 7 9 0 PCTIUS96100125 The user interface 301 may have many types o~ e,l,L,d.li"~e"l~. For example the user interface may be a dedicated personal computer and in that event may be i". ur~.u,dLdd within the terminal 100. In other ~"~L,od;",~"t., the data communication device 300 may be one of many 5 devices coupled to a network and may have an overall system controller such as a Motorola DAS 925 with a system manager described in detail in the pending United States Patent Application Serial No. 08/285 260 entitled ~Advanced Communication System Architecturen filed August 3 1994 andi,,~u,uol byreferenceherein. Inthatcase theuser 10 interface 301 may be ill~GIluuld~dd within the overall system controller which could be used to simultaneously configure all of the data communication devices 300 for the desired operating mode to dU~rU~Jlidldly match the installed PSTN or digital network.
As shown in FIG. 4 the controller 304 is co~ Irla~hl~a to the terminal 100 through transmit data line 301 and receive data line 302. The transmit and receive data lines 301 and 302 may be i"~Gr~,GrdIed within any ap~,,upridIe interface and cabling dlldl~ge~ llI. The controller 304 which may be a Motorola 68302 ~ ucurlll~ is coupled via data bus 305 to a data pump 308 which may be a Motorola 56002 general digital 20 signal processor plu~ld"""dd as a data pump. The data pump 308 receives data command signals and other i"fur",dLion from the controller 304 and the data pump 308 then generates a sampled data signal. The data pump 308 is also coupled via bus 350 to a first codec (ncoder-decoder) 310. A coder-decoder is known as and referred to in 25 the communications field as a codecn and shall also be referred to herein as a "codec~. The first codec 310 is preferably a linear codec and receives the sampled data signal from the data pump typically at a samplir~g rate of 9600 samples per second and then generates a modulated analog signal from the sampled data signal. The first or linear 30 codec 310 is also known and may be i,,,ul~l,,e,,L~d as an analog-to-digital (A/D) converter and digital-to-analog (D/A) converter. The modulated analog signal from the linear codec 310 is ~Idl,~",illed via line or bus 352 to the first switch 312. In the preferred ~",Lodi",e"I the first switch 312 is an analog switch and may be im~ ",~"led in any number 35 of forms such as a solid state or ",ecl,a"i.;al relay or as a discrete 21 887~0 WO 96127241 PCT/US96/Oill25 transistor or integrated circuit dl I dl)y611 ~el 1l (Ç,~9~, CMOS, BJT). The first switeh 312 may also include a plurality of otherwise separate switching i"a~:l,d"i~",s, for example, to c~r,~,o,~d to aaeh separate data path of the data busses. The switch 312, in tum, in response to a control signal 5 l,d"~".;lled via iine 326, may route the modulated analog signal from the linear codec 310 to a first interface circuit, shown in FIG. 4 as the analog interface circuit 314, via bus 354, or may route the modulated analog siynal to the second codec 316, shown in FIG. 4 as a preferably a non-linear PCM (pulse code modulation) codec 316, via bus 356.
Continuing to refer to FIG. 4, the processor 370 consists of a ",i~"uplu.~asaor, such as an Intel 8032, and digital switching circuits, such as a digital multiplexer (~MUX~), to form a ~r.~yldr"",dL,le distributed switching Illtll.:lldllialll. The processor 370 provides a control signal to the first swltch 312 via line 326. In the preferred e",l)~,~i",Q"I, the control 15 signal has first and second values, such as a high voltage (a logic one (1)), and a low voltage (a logic zero (0)). The switch 312, in response to the control signal having the first value, such as a high voltage, transmits the modulated analog signal from the linQar codec 310 to the first (analog) interface circuit 314 via bus 354, and in response to the control 20 signal having the second value, such as a low voUage, transmits the mn~ ted analog signal to the non-linear PCM codec (or ~PCM codecN) 316 via bus 356. Al~ 'n~o'y, the control signal having two values may also be consi~ d to be two signals and, in that event, may be cun~icle,~d first and second control signals. From the analog interface 25 drcuit 314, the modulated analog signal may then be lldn:,",illad via line 1 û6 through the first communications netwûrk shown in FIG. 4 as PSTN
126, and in this mode, the data communications device 300 is operating in a first mode as an analog modem. The first interface circuit such as the analog interface circuit 314 would also typically provide a variety of 30 functions, such as power level setting, il"~,eddllce matching, and may include hybrid circuitry to transfer i~fu~ d~ion from two sets of twisted pair l,d,,:,,,,is:,lun lines to one pair of lld~s"-i ,sion lines.
The processor 370 is further coupled to the second (PCM) codec 316 via bus 358, to the analog interface circuit 314 via bus 364, to the 35 controller 304 via bus 366, and to the digital interface cirCuit 318 via bus ~ W0 96/27241 2 1 ~ ~ 7 9 0 r~l,u~ - -t ILS

362. In response to the control signal from the processor 370 having the second value, such as a low voltage, the switch 312 transmits the rnn~ rt analos sisnal to the PCM codec 316. The PCM codec disitally encodes the modulated analog signal using a pulse code 5 modulation scheme to provide a digital modem signal and, in this second operating mode, the data communication device is operating as a digital modem. The PCM codec 316 transmits the digital modem signal to the processor 370, which routes or transmits the the digital modem signal to the second interface circuit, shown in FIG. 4 as digital interface circuit 318, via bus 362. The second or digital interface circuit 318 is co~rle~hle to a second communications network, shown in FIG. 4 as digital network 228, and ~,,u~esses the digital modem signal for l,dns",issiùn overthe second (digital) network. For example, the digital interface circuit may act as a time division multiplexer to place the digital 15 modem signal, havins a DS0 format, in the apprupridl~ digital channel or time slot.
The processor 370 also receives from and transmits to the controller 304, via bus 366, various data signals and control signals. In the ev~nt the data communication device 300 is to be operable in a third 20 operating mode, as a terminal adapter, as dt,tt:"";"ed by one of the plurality of user command signals from the user interface, the processor transmits a processor command signal to the controller via bus 366. In the third or terminal adapter mode, the controller ~,u~,esses digital illfUrllld~iùli received from the termi~al to fomm a digital i~fur~di;ùn signal,25 and transmits the digital i, ,fur,, " ~ signal to the processor 370 via bus 366. The processor 370, in turn, routes or transmits the digital i"fur",c~ signal via bus 362 to the digital inter~ace circuit 318 for Ildl 1~ ,sion over the digital network 228. The digital interface circuit 318 also p,u~esses the digital il,lu"".~t;oli signal for lldl-s",ia~ion over 30 the digital network, in a manner identical to the pluCea:,il,g of a digital modem signal discussed above.
While the prefenred ~"ILo~il"~"~ of the present invention illustrated in FIG. 4 has been described in detail with regard to i"'~ ", ~i~n l,d"~",;~,sion, it will be u"de,~luod by those skilled in the art that a similar analysis applies with regard to i~u~ reception.

W096127241 2 1 887qQ P~ 5 ~

Accordingly, such data or i,,furl,, ~i~n ~,d,)a",isaion and reception are ~enerally referred to as data or illfull~l 1 transfer to acc~"" ' the bi-di,t,..tional flow of data.
In summary, FIG. 4 illustrates a data communications device 5 s~:~cth~ operable in at least one of a plurality of operating modes, including a first operating mode and a second operating mode, the data communications deYice co~ ~rl~hle to a terminal and to at least one of a plurality of communications networks for l,d"s~"i"g data between the terminal and one of the plurality of communications networks, including a 10 first communications network and a second communications network, the data communications device c~,,,urisi,,g. a controller; a data pump coupled to the controller; a first codec coupled to the data pump; a second codec; a first interface circuit co~ ~rle~hle to the first communications network; a second interface circuit ~n~rl~ble to the 15 second communications network; a first switch coupled to the first codec, to the second codec and to the first interface circuit; and a processor coupled to the controller, to the second codec, to the first int2rface circuit, to the second interface circuit, and to the first switch, the processor I~pGr,~ , to at least one o~ a plurality of command signals to sele..t~
configure the data communications device for operation in the first operating mode for communications through the first communications network and for operation in the second operating mode for communications through the second communications network. The various first and second codecs may be linear or non-linear, and in the preferred e",L~o-~i",e"~, the first codec is a linear codec and the second codec is a non-linear PCM codec, having a mu-law or an A-law co,,,uandur. The first and second communications networks may be a PSTN, T1, E1, ISDN, or any other analog or digital communications networks.
Accordingly, FIG. 4 also illustrates a data communications deYice wherein the first communications network is a public switched telephone network, the second communications network is a digital communications network, the first interface circuit is an analog interface circuit, the second interface circuit is a digital interface circuit; and wherein the processor is ,t:~,on~i~rc to a first command signal of the W096/2724l 2 l 8 8 7 9 0 PCTIUS9610012~i plurality of command signals to produce a first control signal to the first switch to sel~. ti~ couple the first codec to the analog interface circuit and to couple the first codec to the second codec whereby the data communications device is configured in an analog modem operating 5 mode when the first codec is coupled to the analog interface circuit and whereby the data communications device is configured in a digltal modem operating mode when the first codec is coupled to the second codec. FIG. 4 further illustratss a data communications device wherein the processor is further responsive to a second command signal of the 10 plurality of command signals to produce a second control signal to the controller whereby the data communications device is configured in a terminal adapter mode for the processor to transfer data through the digital interface circuit to the digital communications network. Also as shown in FIG. 4, the data communications device may further comprise 15 an input port coupled to the processor and co~lrle~hle to a user interface for entry of at least one of the plurality of command signals.
FIG. 5 is a block diagram which illustrates the distributed switching ",e11,a";_." of the processor 370 in the preferred e,nbocli",e"l of the present invention. In the preferred e"lL.odi",~ r,l the typical "analog 20 modem aspects~ of the data communication device 300, namely the controller 304 and the data pump 308, do not require any separate i" " -~ or ~IUy~d~ y concer";ny the type of network with which the data communication device 300 will be communicating. For example these analog modem aspects do not need to be pruy,d,,,,,,ed 25 to recognize or otherwise rknow~ if the device will be coupled to a PSTN
or a digital network. In the preferred embodiment as shown in FIG. 5, this is a~co",~,l;. :,ed through the processor 370, which includes distributed switching circuits 376 and digital multiplexers 375 CO~ illy a distributed switching ",eol,anis"" such that pr~dtl~r",i"ed signalling 30 and n ) i~,~u""dlion l,dns",ill~d to and from the network (via bus 362 and bus 364) are either l,d"~",illed (switched through) to and from the controller 304, or are simulated by the processor 370, and the simulated signalling illCu~lll io n is then l,d,\a",illed (switched through) to and from the controller 304. The ~,~d~lt,r",i,)ed signalling i"fur",dliol, 35 (or plurality of i~urll ~ signals) would typically include for the analog W096/27241 21 887qO r~ 5 ~

mode, the ring sisnal to the controller via line 380, line current to the controller via line 381, the off hook signal from the controller via line 382, and the loop bits (or loop signal) from the controller via line 383, and for the digital mode, signalling bits such as the A and B signalling bits (and, 5 for other formats, also C and D signalling bits) on bus 362. The off hook and the ring signals are also known as r,: liud~;ùn signals and, as used herein, ar~ ref~rred to ~ 6~ with the other signals as signalling i"' r,,,dliui~ or as i"f~.~" ~ signals. Lines 380, 381, 382, and 383 may also be part of the bus 366 coupling the controller 304 and the processor 370, and are shown as separate lines in FIG. 5 (and in FIG. 6) for ease of reference purposes only.
FIG. 6 is a block diagram illustrating in greater detail the digital m~ x (~MUXn) 375 of the processor 370. The multiplexers 375 are controlled by a MUX control signal on line 392 from other parts of the processor 370, as configured by the plurality of user command signals discussed a'oove. As shown in FIG. 6, the ring signal to the controller on line 380 may be lld"~lllitl~:d directly from the analog interface circuit 314 on line 384 or may be simulated by the processor and ~Idl)~ d on line 385, in response to cr ~ a,u~ or equivalent digital signalling i"lur",dtion from the digital interface circuit 318. The line current on line 381 also may be lldllalllitl~d directly from the analog interface drcuit 314 on line 386 or may be simulated by the processor and lldllalllill~d on line 387, also in response to G~ ,or, ii"~ digital signalling i"fur",dLiù,~ from the digital interface circuit 318. The off hook signal from the controller (to initiate or place a call) on line 382 may be ~,d,~s",illed direGtly to the analog interface circuit 314 on line 388 or may be simulated by the processor (which generates the ~I~,C ru~rid~d signalling bits), and lldl~s,,,i~I~d on line 387 to the digital interface circuit 318. Similarly, the loop bits from the controller ~for diagnostic or "training" pur,ooses) on line 383 also may be lldi-s"~ d directly to the analog interface circuit 314 on line 39û or may be lldll~lllilI~ on line 391 to ûther parts of the processor (which performs the c,pp,UuridIe software loops based upon the loop bits). The digital interface signalling bits, such as the A and B signalling bits, may vary depen-~i"g upon the actual signalling scheme employed in the particular network, such as LOOP, GROUND, TRUNK, TRUNK with ~ wos6/2724l 21 R8790 r~ 6.'~ 125 WINK, FEATURE GROUP B, and FEATURE GROUP D. These various modes are user selectable (or p,uy,d,,,,,,abld) through the plurality of user command signals entered via the user interface 301.
In summary, FIG. 5 and FIG. 6 further illustrate a data 5 communications device wherein the processor, in response to digital signalling j"t~ tic 1 from a digital network, provides c~"~:,,uol~di"y simulated analog signalling i,,fur,,,dliùl, to the controller; and wherein the processor, in response to analog signalling i"'t ",d~i~n from the controller, provides ctj"t,:,por,diny simulated digital signalling 10 i"lur", -n to a digital network. In addition, the analog signalling illlull,, 1 may comprise a ring signal, line current, off hook, and loop bits, and the digital signalling illlulllldliùl~ may comprise A and B bits.
FIG. 7 is a software flow diagram which illustrates the muUiple configuration and data transfer method of the preferred el"l,o~i",t~"l of 15 the present invention. The method begins at start step 700, and the temminal sends data to the controller, step 710. The processor dttt7lill;l,ds whether an analog modem or digital modem conneution is requested, step 720. If a modem cu"na~tid~ is not requested, the data communication device proceeds in terminal adapter mode and converts 20 the data from the terminal 100 to a terminal adapter mode format, step 790. The data communication device 300 then ebld~lishes a co~ e.;lion to the digital network, step 792, and transmits data to (and from) the remote terminal adapter over the digital network, step 794.
Continuing to refer to FIG. 7, if a modem conneu~ n is requested 25 in step 720, the data from the terminal is converted to a sampled analog signal, step 730, and the sampled analog signal is converted to an analog modem signal, step 740. The processor then del~r",i"ds whether a PSTN c;t nne~,ti.~n is requested, step 750. If a PSTN conneution is requested, a conne~,~ion is e:,~dLlir,l)ed with a remote modem via the 30 PSTN, step 760, and the analog modem signal is lldll:,lllitlt:d to (or received from) the remote modem, step 762. If a PSTN col,~ is not requested in step 750, the analog modem signal is converted to a digital modem signal, step 770. The data communications device then e~ ,hes a connection to the remote modem over the digital network W096127241 21 88790 r~~ v Et~l~S ,~

(and the PSTN), step 772 and transfers data to and from the remote modem over the digital network and the PSTN, stap 774.
In summary FIG. 7 illustrates a method of sele~ thri~ly operating a data communications device in at least one of a plurality of operating modes, including a first operating mode and a second operating mode the data communications device co~ IrleAhle to a terminal and to at least one of a plurality of communications networks for lld,la~ data between the terminal and one of the plurality of communications networks including a digital communications network and an analog communications network, the method C~ ,ulisilly: (a) receiving data from the terminal; (b) selecting an operating mode which may further include entering at least one of a plurality of user command signals; (c~
the received data to terminal adapter format data when the terminal adapter operating mode has been selected and ~Idlla~tlrlill~ the terminal adapter format data to or from the digital network; (d) modulating the received data to form an analog modem signal when the modem operating mode has been sQlected; (e) routing the analog modem signal to the analog network when a analog modem operating mode has been selected; and (f) digitally encoding the analog modem signal and routing the digitaily encoded analog modem signal to the digital network when a digital modem operating mode has been selected. Steps (e) and (f) above may also fui-ther comprise: providing a control signal to selectively engage the analog communication network or the digital communication network.
In addition, as illustrated in FIGS. 4-7 the method of operating a data communications device of the present invention further i ~",~,iaes.
(g) r~:.j.o" ii"g to analog and digital signalling information. This step in tunn may fuither include: (91) simulating analog signalling ill~ulllldLio from received pr~dt,l~ll"i"ed digital signalling information; and (92) simulating digital signalling illi'Ulllld~ for lldns,llisvi~n from predut~r",i"e~ analog signalling information.
FIG. 8 is a block diagram which illustrates a second e",i.~cii",t"~l of the present invention. As shown in FIG. 8 the temminal 100 is co~pleAhl~ to the data communications device 400 via transmit line 150 and receive line 151. These transmit and receive lines 150 and 151 are ~ W0 96/27241 2 ~ 8 8 7 q O

coupled to an analog modem 420, which transmits and receives an analog modem signal over bus 422. Bus 422 is coupled to a switch 412.
In response to a cont~ol signal via line 415, the switch 412 may route the analog modem signal to the analog interface circuit 314 via bus 414, for 5 lld~SIII;~ tiun over the PSTN 126. Also in response to a control signal via line 415, the switch 412 may route the analog modem sisnal via bus 416 to the PCM codec 408. The PCM codec 408 converts the analog modem signal to a digital modem signal l,d" ,",illed to the digital interface circuit 318 via bus 418, for l,dns",ission overthe digital network 228.
In summary, FIG. 8 illustrates a data communications device s~l~.,li~ly operable in an analog modem mode and in a digital modem mode, the data communication device ~o~rleAhle to a terminal, and rm Ip~^h~e to a public switched telephone network or to a digital communication network, the data communication device co"",,i~i"~. an analog modem co~ IrleAhle to the terminal; a PCM codec; an analog interface circuit co~ lpl~-hle to the public switched telephone network; a digltal interface circuit coupled to the PCM codec and co~r~eAb~e to the digital communication network; and a switch coupled to the analog modem, to the PCM codec and to the analog interface circuit, the switch ~ C to a control signal to sel~c.i~ cly couple the analog modem to the analog interface circuit and to couple the analog modem to the PCM
codec, whereby the data communication device is operable in the analog modem mode when the analog modem is coupled to the analog interface circuit, and whereby the data communication device is operable in the digital modem mode when the analog modem is coupled to the PCM
codec.
FIG. 9 is a block diagram which illustrates a third el,lLtotii",er,l of the present invention. The terminal 1 ûû is co~ Irle~hle to the data communications device 500, also via transmit and receive lines 150 and 151. Transmit and receive lines 150 and 151 are coupled to a controller 504~ The controller 504 is coupled to data pump 508 via bus 505, and to the digital interface circuit 518 via bus 560. The data pump 508 contains a PCM codec i,,~t,,,u.' , as described and claimed in U.S. Patent No.
5,365,545, issued November 15, 1994, entitled "Modem - Channel Bank Converter~, i,,.;c.r,,,tu,dl~d by reference herein. Among otherthings, the 21 88791~ --PCM codec i"'.~ I -' - may convert sampled analog data, sampled at a rate o~ 9600 samples per second, to sampled disital data, sampled at a rate of 8000 samplQs per second. In response to a control signal, which may be lldllalll"' ' frorn the terminal 100 through the controller 504, 5 senerated by the controllsr 504 or otherwise provided by the controller 504, the data pump 506 may generate a sampled analog data signal I~dlla"~ d to the linear codec 512 via bus 510, or may generate a digital modem signal lldllall "' '~ to the di3ital interface circuit 518 via bus 558.
The linear codec 512 convarts the sampled analog data signal to an 10 analog modem signal, which is then lldlls",itl~d to the analog interfac~
circuit 514 for l, dl lal "iasiun over the PSTN. The digital inter~ace circuit 518 plu~.ess~s the digital modem signal for ~IdilSlllia~iOn over the digital network.
In summary, FIG. 9 illustrates a data communications d~vice 15 ~ 'y operable as an analog modem, as a digital modem, and as a terminal adapter, co~nlsRhl~ to a public switched telephone network and to a digital communication network, the data communications device c~",,~.r,ai"y. a data pump, the data pump having a PCM codec i" ~ ' ' , a linear codec coupled to the data pump; an analog 20 interface circuit coupled to the lin~ar codec and co~ IrleAble to the public switched telephone network; a digital interface circuit co~rl~Ahle to the digital communication network; a controller coupled to the data pump and to the digital interface circuit, the controller s~l~..tl~,ly providing a first control signal to the data pump to selectively operate the data pump 25 in an analog mode and engage the linear codec and the analog interface circuit, the controller further selectively providing a second control signal to the data pump to sel~..ti.~ly operate the data pump in a digital mode and to engage the digital interface circuit, whereby the data communication device is operable as an analog modem when the data 30 pump is in the analos mode, whereby the data communication device is operable as a digital modem when the data pump is in the digital mode, and whereby the data communication device is operable aâ a terminal adapter when the data pump is not in either the analog mode or in the digital mode.

~ W096127241 21~ a8790 P~
As is evident fnom the various e,,lbu.li,,,~r,~a of the present invention diseussed above, the data communieation deviee disclosed herein con ~t~s a single, integrated device which is capable ot eonfiguring and reconfiguring for operation in a variety of modes, such as 5 operating as an analog modem, as a digital modem, and as a temminal adapter, and is further eapable of eommunieating data over a variety of types of otherwise ~ ,",~ analog and digital networks. As l~tnl )~ed above, the prior art ess~ required separate and indt,l,~nd~"l deviees or other hardware to provide for data 10 eommunieation over these various networks.
The novel data eommunieation deviee of the present invention is the first sueh deviee to be c~"-~ d~le, reconfigurable, or ''~I.y,ddedL,le~
to meet the potentially changing requirements of the user. In addition, the data eommunieation device may be eonverted or reeonfigured to a 15 different mode of operation without any hardware con-r,raion, addition, or s~ tion, providing yet additional advantages. First, the data eommunieation deviee may be eonfigured or reconfigured remotely, through the user interface, which may have its own network <,~pAI. ~ ~ic, Accordingly, an installer or other serviee personnel may eonfigure andtor 20 reeonfigure the data eommunieation device from a remote loeation, for example, from a manufacturing facility located across the country.
Seeond, the data communication device hardware is eonvertable and u~ylddedLJle, such that a users current investment in data eommunieations equipment may be preserved nuL~i llaLdrldillg network 25 ehanges. For example, a user's eurrent needs may indieate eontinued use of a PSTN for data n~t~. ki"g. The data communications device of the present invention would provide for the user to currently connect its data communications equipment through the PSTN, while simultaneously pnoviding for future conne,,1iun to digital networks through 3û the same hardware, ~,t,ser./i.,g the user's current equipment investment while providing for ~r y in the future. When this upy,ddable data communication device according to the present invention is used in a digital or an analog network system, it is possible to make a heretofore unavailable effortless transition between the analog network and the 35 digital network.

WO96127241 21 8g790 r l~u~ ot~

Third, because the data communications device disclosed herein is capable of combinin~ three separate devic~s into one integrated, fully functioning device, the data communications device disclosed herein provides for powar ~onser~d~i~n, as fewer devices are required, and 5 acco,.l~"~ , fewer devices are required to be powered at any given time.
In addition, because the single, integrated data communications device disclosed herein performs the functions of three heretofore separate devices, the data communications deYice of the present invention ~iy"i~i~d"lly reduces the number of devices required at a network 10 i" " ~icn and may siylli~i~dlltl~ reduce the housing and other space requirements of the network facility.
From the fore~oing, it will be observed that numerous variations and ",- "" .)s may be effect~d without departing from the spirit and scope of the novel concept of the invention. It is to be ~lld~lalOod that no 15 limltation with respect to the specific methods and apparatus illustrated herein is intended or should be inferred. It is, of course, inta~ded to cover by the appended claims all such ",- "" " ).1S as fall within the scop~ of the claims. The invention is further defined by the following claims.

Claims

CLAIMS:

1. A data communications device selectively operable in at least one of a plurality of operating modes, including a first operating mode and a second operating mode, the data communications device coupleable to a terminal and to at least one of a plurality of communications networks for transferring data between the terminal and one of the plurality of communications networks, including a first communications network and a second communications network,the data communications device comprising:
a controller;
a data pump coupled to the controller;
a first codec coupled to the data pump;
a second codec;
a first interface circuit coupleable to the first communications network;
a second interface circuit coupleable to the second communications network;
a first switch coupled to the first codec, to the second codec and to the first interface circuit; and a processor coupled to the controller, to the second codec, to the first interface circuit, to the second interface circuit, and to the first switch, the processor responsive to at least one of a plurality of command signals to selectively configure the data communications device for operation in the first operating mode for communications through the first communications network and for operation in the second operating mode for communications through the second communications network.

2. The data communications device of claim 1 wherein the first codec further comprises a linear codec.

3. The data communications device of claim 1 wherein the second codec further comprises a non-linear codec.

4. The data communications device of claim 1 wherein the second codec further comprises a mu-law PCM codec.

5. The data communications device of claim 1, further comprising:
the first communications network is a public switched telephone network, the second communications network is a digital communications network, the first interface circuit is an analog interface circuit, the second interface circuit is a digital interface circuit; and wherein the processor is responsive to a first command signal of the plurality of command signals to produce a first control signal to the first switch to selectively couple the first codec to the analog interface circuit and to couple the first codec to the second codec, whereby the data communications device is configured in an analog modem operating mode when the first codec is coupled to the analog interface circuit, and whereby the data communications device is configured in a digital modern operating mode when the first codec is coupled to the second codec.

6. The data communications device of claim 5 further comprising:
the processor is further responsive to a second command signal of the plurality of command signals to produce a second control signal to the controller whereby the data communications device is configured in a terminal adapter mode for the processor to transfer data through the digital interface circuit to the digital communications network.

7. The data communications device of claim 6 wherein the first codec further comprises a linear codec and wherein the second codec is a PCM
codec.

8. A method of selectively operating a data communications device in at least one of a plurality of operating modes, comprising of a first operating mode and a second operating mode, the data communications device coupleable to a terminal and to at least one of a plurality of communications networks for transferring data between the terminal and one of the plurality of communications networks, including a digital communications network and an analog communications network, the method comprising:
(a) receiving data from the terminal;
(b) selecting an operating mode;
(c) converting the received data to temminal adapter format data when the terminal adapter operating mode has been selected and transferring the temminal adapter format data to or from the digital network;
(d) modulating the received data to form an analog modem signal when the modem operating mode has been selected;
(e) routing the analog modem signal to the analog network when a analog modem operating mode has been selected; and (f) digitally encoding the analog modem signal and routing the digitally encoded analog modem signal to the digital network when a digital modem operating mode has been selected.

9. The method of operating a data communications device of claim 8 further comprising:
(g) responding to analog and digital signalling information.

10. The method of operating a data communications device of claim 9 wherein step (g) further comprises:
(g1) simulating analog signalling information from received predetermined digital signalling information; and (g2) simulating digital signalling information for transmission from predetermined analog signaliing information.