CA2161018A1 - Telecom adapter for interfacing computing devices to the analog telephone network - Google Patents
Telecom adapter for interfacing computing devices to the analog telephone networkInfo
- Publication number
- CA2161018A1 CA2161018A1 CA002161018A CA2161018A CA2161018A1 CA 2161018 A1 CA2161018 A1 CA 2161018A1 CA 002161018 A CA002161018 A CA 002161018A CA 2161018 A CA2161018 A CA 2161018A CA 2161018 A1 CA2161018 A1 CA 2161018A1
- Authority
- CA
- Canada
- Prior art keywords
- adapter
- clock
- analog
- telecom
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
- H04M11/06—Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
- H04M11/066—Telephone sets adapted for data transmision
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
- H04M11/06—Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
Abstract
A telecommunications adapter interfaces computing devices to the analog telephone network, achieving a tightly integrated digital telecommunications link with the analog telephone network. The telecommunications adapter takes advantage of certain host resources including, preferably, the computer's signal processor, the computer's power supply and a computer/peripheral serial interface. System cost for digital communications over the analog network is therefore reduced. Furthermore, the telecommunications adapter is able to accept and deliver a digitized representation of the analog (voice) data stream in real time, supporting both existing and future voice-band communications technologies. Finally, the invention facilitates rapid and inexpensive adaptation to the various international telephone standards. Instead of replacing an entire modem, a relatively inexpensive satellite processor (i.e., the telecom adapter) may be replaced instead. Data stream synchronization is achieved between the digital data stream and a time-driven DSP task list within the computer. Wide-area communications data streams -either data or voice- obtained from analog telephone lines may therefore be conveniently manipulated and blended into the computer's sound facilities, for example.
Description
Wo 94/27399 TELECOM ADAPT~ FOR INTERFACING COMPUTING
DEVICES TO THE ANALOG TELEPHONE NETWORK
BACKGROUND OF TH~ INVENIION
Field of the Invention The present invention relates to data teleco.. ~ .;r~tions and more particularly to data teleco.. ~ ir~ti-ns over the wide-area analog t~l~hone nelwolk.
State of the Art The analog telephonf network by its nature uses analog 10 elf~tric ~l cign~lling over copper wire bel~ a central office and .-U.~ lf phr nf sets. Coll~uler co~ unic~tionc~ being based on digital cigrl~llin~, require an analog to digital conversion to be pelrolllled in order to support digital communir~tionc over the analog phone network. This conversion is typically done by a 15 modem (mod~ trJr/dfemr~ul~tor). This approach is adequate for basic digital data co.. ~-ir~tic-nc, and has been employed for the last several dec~les A typical modem concictc of a digital signal pl~cessol (DSP), a hybrid 2/4 wire interface, a codec, a mic~conlloller to manage system functionc, and a serial interf~r~
20 to the COIIIPUI~, typically using the RS232C cign~lling approach with ASCII enco-ling.
There are cignifi~nt disadvantages to this approach. By emlxd-ling the entire comm--nir~tions and signal proc~-ccing wo 94l273g9 ,2~6l~l8 filnrtinnqlity in an PYtçrnql device, a lower bound is placed on the cost of the device. FurthP-rrnore, the RS232C/ASCII signqlling co~venlion precludes access to non-digital (~log) signals that may be carried on the tPlephonP network. Direct` àccess to a digital 5 ~ ;nn of the analog ch-q-nnrl is réquired for voice l~nil;nn, text-to-speech conversion, proprietary enr~iing of video signals, and other related t-Prhnologies. Finally, conventional m~lernc do not allow for adaptation to the various in~ l;ona telP.phQnP standards, requiring instead repl~r~mPnt of the entire 10 m~?dçrn.
SUMMARY OF THE INVENTION
The present invention, generally spe~king, provides a teleco----"l~ ieq-tinn~ adapter for int~Prf~cing co~ uling devices to the analog t~lephon~P nclwol!~ that overcomes the foregoing 15 disadvantages and achieves a tightly integld~ed digital t 1~4~ n .~";mlc link with the analog plP~hnnç n~lwolL The teleco..,...~nirq~ionc adapter takes advantage of certain host C~ulces inr,lur~ing, preferably, the Colll~ult~l'S signal pl~cessor, the CO"Iput l's power supply and a co",puler/pf ;ph. al serial 20 intAPrf"ee. System cost for digital cGIllllllln~ qtion~ over the analog n~;lwol~ is thclefo~ reduced. Furthe~,..o~, the telecom,--un;r~tions adapter is able to accept and deliver a iigiti7~.d l~ n~;nn of the analog (voice) data stream in real time, suppol~ing both eYi~ting and future voice-band co....~ ni~q-tions technologies. Finally, the 25 invention fqrilitqtçs rapid and ini .~ns;~e adaptation to the various WO 94/27399 `
l;onal telephone standards. Instead of replacing an entire modem, a relatively ~eApensi~e ~tP-llite pr~cessor (i.e., the telecom adapter) may be repl~ced inc~^~
In particular, in accol lance with one embodiment of the 5 prOEnt invention, a telecommlmir~tion adapter for inyulling to a co,l,~ ~r woll~lion a digital data stream l~)fe~n~;ng a real time contin~lolls analog signal inchl~les ci~.;uil,~ for receiving an analog signal and converting the analog signal to a voice-rate or greater digital data stream and interf:~^e Cill;uiLl~ for receiving the digital 10 data stream and inp~ g the digital data stream to the CollllJut~
wo~L~ ;on through a colllnlunic~tionc port of the co",puler w~..L~ ;on. In accoldance with another aspect of the present invention, data stream syncl~ ion is achieved be~ the digital data stream and a time-driven DSP task list within the 15 co",puler. Wide-area collllllunir~tions data streams --either data or voice-- obtained from analog telephone lines may theleful~ be con~r~x~ienll~ manipulated and b4nd~ into the co-..ru~ ~'s sound f:~-ilitit s, for ~Y~mple.
BRIEP DESCRIPIION OF THE DRAWINGS
The present invention may be further understood from the following deseliption in conjunction with the ~pen~ed d~wings. In the drawings:
~2l6lol8 Figure 1 is a simp1ifi~d block diagram of a co,.,puta system in which the present invention may be used;
.~ ~
Figure 2 is a block diagram of a telecom adapter in accordance with the present invention;
Figure 3 is a diagram of a typical time-division-multiplex data stream;
Figure 4 is a diagram of a possible information field data frame of the data stream of Figure 3;
Figure S is a block diagram of a data stream ~nchrl~ni7~tion arr~ngement; and Figures ~8 illustrate a procedure used to y~ual~dl tee time-~,f~nce synchroni7~ti~ n belween the col"puler system and the ~leco.,l adapter.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS
The co,,,puler system of Figure 1 is exempl~ry of a wide variety of cG."l,ul~r systems, both large and small, in which serially conn~t~ co.. ~Jni~tion~ devices may be found and with which the present telecom adapta may be used. An address bus 20 and a data bus connecl a central proces~ing unit (CPU) to read-only WO 94/2739g 216 1018 PCT/U594/04782 memory (ROM), and, through bus transceivers, to random acre~s memory (RAM) and to a UART (universal asynchronous recei~c.
h; ~ ) or a USART (uni~l synch~nous/as~l,.cl,l(,nuus r tr~n~ el) that provides an int~rf~ to a serial I/O
S port(s). A tcl~w... adapter is shown connected to th~e serial port.
The present tel~lll adapter provides a versatile, general-~ull~ose interf~ to the wide-area communir~tion~ analog tel~phonP
nclwclL Referring to Figure 2, the telecom adapter cont~in~ analog to digital conversion f~iliti~s (103), electr~ and n.Pr~
10 int~rfaee hanlw~e (105), clock gene.~lion and/or recovery circuits (104), serial-to-parallel t~nc1~ti~n hardw~ (101) to eYc~h~nge the digital data bcl~.xn the telecom adapter and host CGIll~ut~l, and a state m~^hine (micl~conhuller 102) which m~nages the s~llcl~lom~t;~n and delivery of digital samples to the host via a 15 time-division-multiplexed data stream. The analog data SLI~..s are derived from signals from the tPl~phone ch~nnel (106) and a standard pl- ~h~ desk set (107).
A serial int~rf~r~ protocol and procedure is defined for 5~l -ching the ~leco." adapter through a short cable to a standard 20 co-....~vni~-~tions port, for example the serial port, of a cG",pu~r w~-k~ ;on. The co~ pul~r wo.k~l~t;on is ~Ccum~ to be e.luipped with direct nlc:~llol~ access (DMA) wl.~.~by DMA may be used to service the serial port and off-load the co-..~ule~s central pr~ c~;ng unit (CPU), allowing continuous real time co.. ~nir~tiQns to be IllAil~t;l;~-~?d. A related ~lotocol and wo g4l273gg ~2l6lol8 pr~dulc, described in U.S. Application Serial Number `
08/058,750, incol~laled herein by reference, enables non-DMA
capable co",~ute,~ to establish through the serial port a high-speed cG~ tinl~s link to digital networks inclu-ling the TntG~ ed 5 Services Digital Network (ISDN) and Private Branch FYch~nge (PBX) n ~,~WOl~, using a more advanced telecom adapter.
~ Pfe ing still to Figure 2, the external telephone network c4nl-~c!~ to the telecom adapter at jack (106). This signal is then c~nditioned by a suitable e1~t-ir~l interface to provide proper 10 signal amplifi~ti~-n and filt.oring before submic~i~n to the codec iti7Pr) interf:^e (103). The codec is c1~ d by an ir~tern~lly g~ c ,-t~l oseill~tor (104). This os~ t~r is also used to derive the telecom sample clock (108) that is delivered to and employed by the host for datastream synchroni7~ti~n as eYpl~inp~ hereinafter.
15 Digitized samples are çlocl~eli belwæn host and telecom adapter bit-~,~nchlunousl~ and in phase with sample ge-~ t;Q~ in the t~,lc~", adapter. Thus no b..rr~.;,.g of digital data within the telecom adapter is l~Uil~d.
Using full-duplex DMA hardware in the co",l)u~, a time-20 division-multipli~d (IDM) interface may be su~ ed. A t-~n~mit h~-l~h~l~P line (110) is provided on the serial interf~ e as shown in Figure 2. When the telecom adapter wishes to eY~h~nge a set of data from a c4ntinUQus bit rate (CBR) real time data stream witn the col"puler, it simply tr~n.~mit~ any bytes to be ll~ns~itl~d to the 25 co,npu~r and then uses the transmit h~n-i~h~k~ line (110) to force wo 94l273g9 PCTtUS94tO4782 ~161018 the co,-,l,u~l to transmit the appropliale number of bytes to the telecom adapter. In this way, the conct~nt bit rate stream can be ,..~in~ d will-Oul any intervention by the collllJulel's CPU.
1~U~P the telecom adapter is dir~lly servicing the source of the 5 stream, namely the co~ ni(~tions line, the telecom adapter is better able than the cGn,puler to ...~in~ the timing of the conct~rlt bit rate stream.
Control of the telecom adapter through the TDM interf~çe is ~lr~,l..-ed by a sorlw~e telecom adapter handler routine in the 10 co--l~u~r. Typically, TDM data streams are broken up into fixed length frames co~cicting of a control field and a data field as shown in Figure 3. The control field carries adapter dependPnt illfo~ n, and the information field carries the data. These frames are ~ ~d at a fLxed period of time, called the frame 15 period. The control field is used by the sorlwar~ handler to set up data buffers for these frames. The specifics of the control field depend on the ~ifir hardware imple ..~n~ n of the telecom adapter.
The information field of the TDM frarne c~nCictc of an 20 integr~l number of ;l~tf.lf .~red sets of data for, in the case of the analog te1P~phQn~P n~lwol~, each of two data streams. The nul~ber bytes in each set for a stream is called t,he stream's int~ ..re factor (lF). A possible frame for the telecom adapter of Figure 2 is shown in Figure 4 in which two streams are int~Prl~P~ved, each with an 25 intPrlP~ve factor of two.
Wo 941273gg PCT/US94/04782 216101~ :;
Each stream in the inl~r~"a~on field is char~ul~ ~ by three p~ the interle~ve factor, orr~ `e number of bytes in e~ch oc~iu~ ce of the stream, the o~fset, or the number of bytes into the info....-l;on field that the first byte of the stream occurs, S and the repeat factor--the offset bcl~cen the first byte of one occul,e. ce of the stream and the first byte of the next occulYellce of the stream. For ~A~"ple, in Figure 4, Stream 2's interlP~ve factor is two, its offset is one, and its repeat factor is two.
Providing for the eY~h~nge of digital real time data streams 10 ~t~cn various co.~.pQnf ntc of the host system and the tP1Pphone netwul!~ enables ih ~r~vol~ing of the host co"".u~r within a larger, possibly global, netwulk of CGnlpul~. Typical colll~ulel s~s~ ",s would include, but are not limited to, sound generation, audio r~or~.ng, video, and so on. In all cases, the host sul~s~", 15 data stream that e~ch~nges dah with the telecom adapter must be phase-synclllo,~iz~d with the telecom data stream.
A plOCC~duf~; for initi~li7~tirn and operation of the tPlP~om adapter by the host cG",~uler, to be describe~ plesenlly in relation to Figure 5, allows vide-area communi~tionc data strearns 20 obt~ined from analog t~PIephon~P lines to be conveniently manipulated and blended into the co",~u~r sound f~cilities~ for e~cample. Ihe host co."l)u~r cont~in~ signal ~f~ S~ g les~ui~s useful for g~l-at;o~ and d~P~tiQn of voice-band data signals (modem), speech gc~.lation, voice ~cog~ ;on, sound synt~PSi~
25 and the like. The pr~lu~e ensure that a precise integer Wo 94l27399 PCT/US94/04782 r~l~tionchip is ,..~ n~d between telecom data and the particular s~sy~tcnl of interestj such that the host intP~ s~lbsy~lll data stream is time-aligned with thé telecom adapter data stream.
Referring to Figure 5, the host co~p~ler system typically S employs a CISC (complex instruction set) microprocessor as the central p,ocessor (213). However, conte~polaly- CISC l,r~cessol~
by their nature lack suffici~-nt pnxes~;ng capacity to treat the digital telecom adapter datastream in real-time. For eY~mple, a V.32 analog modem signal could not be generated and delivered to the 10 tcle~l" adapter by the CISC CPU. Th~.efore, a Digital Signal ~ocessor (DSP) (205) is employed as a coprocessor to pelrol"~ the laborious but requisite signal tran~Ç.,l",ation colllput;~;on~ on the telecom data stream.
The DSP is a general purpose resource at the ~ l of 15 po~.ltially several host computer clients. The host co",~ ter o~ ;n~, system s~rlw~ th~erole employs a time-based sorlwdr~
s~h~--ling algo,itl"" to ensure its clients of re~col-~hle access to the DSP pr~s~ g ,~ soulces. The time-based scheduling concept is based on a list of tasks (206) that are defined by the host processor, 20 and e~uted in a sequential manner on the DSP. The time-base atomic unit is called a frame. For this reason the time-based s~ i~ system is also called a frame-based signal ~roceC~;,-g system.
wo g4l273gg 216iO~8 Operation of the telecom adapter is as follows. The bit-sy..cl,r~)nous clock (108) and bidire~tinnq-l datastreams are delivered to the host cG-,-puler on the serial interf~,ce (213). The serial data is clocked into a serial-to-parallel converter (211) according to the 5 trqnsitinn~ of the bit-synchronous clock. Since the datastream is req1tim~, continUQus~ and must be delivered reliably, regardless of tasks that may be running on the central pr~cessol (213), a deAi(~q~t~d Direct Memory Access (DMA) chqnnel (212) is used.
The DMA circuit moves data between the Telecom Sample Buffers 10 (210) and the telecom adapter.
At the same time, the DSP (205) may be ex~uting a parallel time-based task such as sound synthesis over the system speakers. In this case the speaker (210) is driven by a codec (207) from the sound sample buffers (209) which are filled as a result of 15 co...l~ul~;on~ made by the DSP. Again, since the datastream is realtime s~/"chr~nous, a DMA chqnnpl is deAi~qt~d to the sound system to ensure reliable transfer of the sound s~mrlos to the speaker.
In order to provide the reliable e~c-h-q-nge of sample data 20 between the host co-"puler sound system and the telecom adapter, the sound sample buffer must m-qintqin a fixed phase and time relqtion~hip with the telecom sample buffer. Note that, at the same time, the DSP op~lates according to a time-based schedllling alE,u~ ll. Th~efolt; the following procedure is implemented.
25 First, the telecom clock, which was previously shown to be bit-wo g4t273gg 216101~ -synchronous and in phase with the datastream delivered by the telecom adapter, is delivered to the host col,lpule~ USART (211) and a Phase-Locked Loop (203). The telecom data clock is used to synchronize the sound clock (201) which nominally operates at an 5 integer mllltiple of the telecom data clock. Thus the sound clock is phase-aligned with the telecom data clock.
The output of the PLL is then passed to a clock divider (204) which reduces the clock frequency to yield a periodic pulse.
This periodic pulse defines the DSP time frame and is used to 10 awaken the DSP and cause it to execute the task list. The tasks are eYe~utçd r~peliti-/ely according to the periodic pulse, which has a nominal period of ten milli~onds. Included in the tadsk list are the sound genc.dlion task(s), the telecom sample pr~cesC;,~ task(s), and a sample rate conversion task. The ~ullJo-ce of the sample rate 15 converter (211) is to transforrn the N samples found in the telecom sample buffer into M c~mplçs loaded into the sound sarnple buffer by the DSP. However, there must be a strict time ~ligr~mPnt beh.~cn the sound buffer and the telecom sample buffer.
Th~er~.~e, the telecom adapter is initi~li7~1 in precise reference to 20 the output of the clock divider (204).
The telecom adapter has a reset line (111) which is driven by the host colllyut~l. The reset line holds the telecom data and clock lines in a ql~ip-~nt state, when asserted. The clock line is activated, and sampling commences, when the reset line is de-25 asserted. A procedure illustrated in Figures 6-8 is executed by the wo 94l273g9 ~- 21 6lol8 t 12 ~;
System CPU (213) whereby the output of the clock divider is monilo,~d, such that the telecom adapter reset input is asserted and released at the a~propliale time to guarantee time-reference synchroni7~tion .
More particularly with reference to Figure 6, prior to time 1, the system CPU has already set up the DMA controller to start receiving data into the third sample of the receiver buffer where the DSP will expect to get the samples at the end of the 10 ms period.
The system CPU has set up the DMA controller to start tr~ncmitting data from the transmit buffer which has been initi~li7~d with two frames worth of null samples. When the system CPU
sees the 10 ms timer fire at time 1, it will active the reset (DTR) signal, bringing the telecom adapter out of the beacon phase and into operation. The telecom adapter will then grab the next receive sample from the codec and transmit it to the host, where DMA will place it into the receive buffer. The telecom adapter will then activate the Tx ~ndch~l~e line long enough to receive one sarnple from the host, which will be fed to the codec at the next c~mpling period. The telecom adapter will continue to exch~nge samples with the host in this way until the reset (DTR) signal is inactivated.
Each sample exc-h~nge consists of the telecom adapter se-rlding four receive bytes to the host and the telecom adapter retrieving four s~ bytes from the host, concicting of one sample for each of two çh~nn~,ls and two bytes per sample.
When the DSP receives a 10 ms intel.~p~ at time 2, there will be 80 receive samples in the receive buffer. The DSP
will block move these ~mpl~s into its own memory. The DSP
must skip every other sample in the buffer since both çll~nn~l's S s~mrl~s are in the buffer. Once the DSP has all the receive samples it will process these and produce transmit samples within 10 ms.
When the next 10 ms time goes off at time 3, the DSP will have placed the transmit samples in the transmit buffer 10 begin~ g with the first location after the initial 160 null samples.
The next time the telecom adapter and host exchange samples the real transmit sample will begin being sent. The maximum delay bel~n a receive sample and its c~lcsponding transmit sample will be two frame periods plus four sample periods, in this case 20 ms + (4*125~s) = 20.5 ms.
After the initi~li7~tion sequence is ex~uted, data is delivered from the telecom adapter to the host computer with both phase and time ~lignm~nt~ Thcçefolc the DSP, which is time edul~ for frame-based proceccing, is assured that the N telecom 20 ~mpllos, which arrive from the telecom adapter via the system DMA hardware, are entirely coincident with the gencl~tion of the M sound samples contitined in the sound sample DMA buffer.
The rorcgoing has described the principles, plefellcd embo~limentc and modes of operation of the present invention.
25 However, the invention should not be construed as limited to the wo g4l27399 - 2~ 6 ~ ~ 14 particular embo~im~-ntc licrucc~. Instead, the above-described ?1 embo~limentc should be regarded as illùstrative rather than restrictive, and it should be al,pr~'laled that v~ tionC may be made in those embotlirnentc by wolkels skilled in the art without S dcp~li~ g from the scope of the invention as defined by the following claims.
DEVICES TO THE ANALOG TELEPHONE NETWORK
BACKGROUND OF TH~ INVENIION
Field of the Invention The present invention relates to data teleco.. ~ .;r~tions and more particularly to data teleco.. ~ ir~ti-ns over the wide-area analog t~l~hone nelwolk.
State of the Art The analog telephonf network by its nature uses analog 10 elf~tric ~l cign~lling over copper wire bel~ a central office and .-U.~ lf phr nf sets. Coll~uler co~ unic~tionc~ being based on digital cigrl~llin~, require an analog to digital conversion to be pelrolllled in order to support digital communir~tionc over the analog phone network. This conversion is typically done by a 15 modem (mod~ trJr/dfemr~ul~tor). This approach is adequate for basic digital data co.. ~-ir~tic-nc, and has been employed for the last several dec~les A typical modem concictc of a digital signal pl~cessol (DSP), a hybrid 2/4 wire interface, a codec, a mic~conlloller to manage system functionc, and a serial interf~r~
20 to the COIIIPUI~, typically using the RS232C cign~lling approach with ASCII enco-ling.
There are cignifi~nt disadvantages to this approach. By emlxd-ling the entire comm--nir~tions and signal proc~-ccing wo 94l273g9 ,2~6l~l8 filnrtinnqlity in an PYtçrnql device, a lower bound is placed on the cost of the device. FurthP-rrnore, the RS232C/ASCII signqlling co~venlion precludes access to non-digital (~log) signals that may be carried on the tPlephonP network. Direct` àccess to a digital 5 ~ ;nn of the analog ch-q-nnrl is réquired for voice l~nil;nn, text-to-speech conversion, proprietary enr~iing of video signals, and other related t-Prhnologies. Finally, conventional m~lernc do not allow for adaptation to the various in~ l;ona telP.phQnP standards, requiring instead repl~r~mPnt of the entire 10 m~?dçrn.
SUMMARY OF THE INVENTION
The present invention, generally spe~king, provides a teleco----"l~ ieq-tinn~ adapter for int~Prf~cing co~ uling devices to the analog t~lephon~P nclwol!~ that overcomes the foregoing 15 disadvantages and achieves a tightly integld~ed digital t 1~4~ n .~";mlc link with the analog plP~hnnç n~lwolL The teleco..,...~nirq~ionc adapter takes advantage of certain host C~ulces inr,lur~ing, preferably, the Colll~ult~l'S signal pl~cessor, the CO"Iput l's power supply and a co",puler/pf ;ph. al serial 20 intAPrf"ee. System cost for digital cGIllllllln~ qtion~ over the analog n~;lwol~ is thclefo~ reduced. Furthe~,..o~, the telecom,--un;r~tions adapter is able to accept and deliver a iigiti7~.d l~ n~;nn of the analog (voice) data stream in real time, suppol~ing both eYi~ting and future voice-band co....~ ni~q-tions technologies. Finally, the 25 invention fqrilitqtçs rapid and ini .~ns;~e adaptation to the various WO 94/27399 `
l;onal telephone standards. Instead of replacing an entire modem, a relatively ~eApensi~e ~tP-llite pr~cessor (i.e., the telecom adapter) may be repl~ced inc~^~
In particular, in accol lance with one embodiment of the 5 prOEnt invention, a telecommlmir~tion adapter for inyulling to a co,l,~ ~r woll~lion a digital data stream l~)fe~n~;ng a real time contin~lolls analog signal inchl~les ci~.;uil,~ for receiving an analog signal and converting the analog signal to a voice-rate or greater digital data stream and interf:~^e Cill;uiLl~ for receiving the digital 10 data stream and inp~ g the digital data stream to the CollllJut~
wo~L~ ;on through a colllnlunic~tionc port of the co",puler w~..L~ ;on. In accoldance with another aspect of the present invention, data stream syncl~ ion is achieved be~ the digital data stream and a time-driven DSP task list within the 15 co",puler. Wide-area collllllunir~tions data streams --either data or voice-- obtained from analog telephone lines may theleful~ be con~r~x~ienll~ manipulated and b4nd~ into the co-..ru~ ~'s sound f:~-ilitit s, for ~Y~mple.
BRIEP DESCRIPIION OF THE DRAWINGS
The present invention may be further understood from the following deseliption in conjunction with the ~pen~ed d~wings. In the drawings:
~2l6lol8 Figure 1 is a simp1ifi~d block diagram of a co,.,puta system in which the present invention may be used;
.~ ~
Figure 2 is a block diagram of a telecom adapter in accordance with the present invention;
Figure 3 is a diagram of a typical time-division-multiplex data stream;
Figure 4 is a diagram of a possible information field data frame of the data stream of Figure 3;
Figure S is a block diagram of a data stream ~nchrl~ni7~tion arr~ngement; and Figures ~8 illustrate a procedure used to y~ual~dl tee time-~,f~nce synchroni7~ti~ n belween the col"puler system and the ~leco.,l adapter.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS
The co,,,puler system of Figure 1 is exempl~ry of a wide variety of cG."l,ul~r systems, both large and small, in which serially conn~t~ co.. ~Jni~tion~ devices may be found and with which the present telecom adapta may be used. An address bus 20 and a data bus connecl a central proces~ing unit (CPU) to read-only WO 94/2739g 216 1018 PCT/U594/04782 memory (ROM), and, through bus transceivers, to random acre~s memory (RAM) and to a UART (universal asynchronous recei~c.
h; ~ ) or a USART (uni~l synch~nous/as~l,.cl,l(,nuus r tr~n~ el) that provides an int~rf~ to a serial I/O
S port(s). A tcl~w... adapter is shown connected to th~e serial port.
The present tel~lll adapter provides a versatile, general-~ull~ose interf~ to the wide-area communir~tion~ analog tel~phonP
nclwclL Referring to Figure 2, the telecom adapter cont~in~ analog to digital conversion f~iliti~s (103), electr~ and n.Pr~
10 int~rfaee hanlw~e (105), clock gene.~lion and/or recovery circuits (104), serial-to-parallel t~nc1~ti~n hardw~ (101) to eYc~h~nge the digital data bcl~.xn the telecom adapter and host CGIll~ut~l, and a state m~^hine (micl~conhuller 102) which m~nages the s~llcl~lom~t;~n and delivery of digital samples to the host via a 15 time-division-multiplexed data stream. The analog data SLI~..s are derived from signals from the tPl~phone ch~nnel (106) and a standard pl- ~h~ desk set (107).
A serial int~rf~r~ protocol and procedure is defined for 5~l -ching the ~leco." adapter through a short cable to a standard 20 co-....~vni~-~tions port, for example the serial port, of a cG",pu~r w~-k~ ;on. The co~ pul~r wo.k~l~t;on is ~Ccum~ to be e.luipped with direct nlc:~llol~ access (DMA) wl.~.~by DMA may be used to service the serial port and off-load the co-..~ule~s central pr~ c~;ng unit (CPU), allowing continuous real time co.. ~nir~tiQns to be IllAil~t;l;~-~?d. A related ~lotocol and wo g4l273gg ~2l6lol8 pr~dulc, described in U.S. Application Serial Number `
08/058,750, incol~laled herein by reference, enables non-DMA
capable co",~ute,~ to establish through the serial port a high-speed cG~ tinl~s link to digital networks inclu-ling the TntG~ ed 5 Services Digital Network (ISDN) and Private Branch FYch~nge (PBX) n ~,~WOl~, using a more advanced telecom adapter.
~ Pfe ing still to Figure 2, the external telephone network c4nl-~c!~ to the telecom adapter at jack (106). This signal is then c~nditioned by a suitable e1~t-ir~l interface to provide proper 10 signal amplifi~ti~-n and filt.oring before submic~i~n to the codec iti7Pr) interf:^e (103). The codec is c1~ d by an ir~tern~lly g~ c ,-t~l oseill~tor (104). This os~ t~r is also used to derive the telecom sample clock (108) that is delivered to and employed by the host for datastream synchroni7~ti~n as eYpl~inp~ hereinafter.
15 Digitized samples are çlocl~eli belwæn host and telecom adapter bit-~,~nchlunousl~ and in phase with sample ge-~ t;Q~ in the t~,lc~", adapter. Thus no b..rr~.;,.g of digital data within the telecom adapter is l~Uil~d.
Using full-duplex DMA hardware in the co",l)u~, a time-20 division-multipli~d (IDM) interface may be su~ ed. A t-~n~mit h~-l~h~l~P line (110) is provided on the serial interf~ e as shown in Figure 2. When the telecom adapter wishes to eY~h~nge a set of data from a c4ntinUQus bit rate (CBR) real time data stream witn the col"puler, it simply tr~n.~mit~ any bytes to be ll~ns~itl~d to the 25 co,npu~r and then uses the transmit h~n-i~h~k~ line (110) to force wo 94l273g9 PCTtUS94tO4782 ~161018 the co,-,l,u~l to transmit the appropliale number of bytes to the telecom adapter. In this way, the conct~nt bit rate stream can be ,..~in~ d will-Oul any intervention by the collllJulel's CPU.
1~U~P the telecom adapter is dir~lly servicing the source of the 5 stream, namely the co~ ni(~tions line, the telecom adapter is better able than the cGn,puler to ...~in~ the timing of the conct~rlt bit rate stream.
Control of the telecom adapter through the TDM interf~çe is ~lr~,l..-ed by a sorlw~e telecom adapter handler routine in the 10 co--l~u~r. Typically, TDM data streams are broken up into fixed length frames co~cicting of a control field and a data field as shown in Figure 3. The control field carries adapter dependPnt illfo~ n, and the information field carries the data. These frames are ~ ~d at a fLxed period of time, called the frame 15 period. The control field is used by the sorlwar~ handler to set up data buffers for these frames. The specifics of the control field depend on the ~ifir hardware imple ..~n~ n of the telecom adapter.
The information field of the TDM frarne c~nCictc of an 20 integr~l number of ;l~tf.lf .~red sets of data for, in the case of the analog te1P~phQn~P n~lwol~, each of two data streams. The nul~ber bytes in each set for a stream is called t,he stream's int~ ..re factor (lF). A possible frame for the telecom adapter of Figure 2 is shown in Figure 4 in which two streams are int~Prl~P~ved, each with an 25 intPrlP~ve factor of two.
Wo 941273gg PCT/US94/04782 216101~ :;
Each stream in the inl~r~"a~on field is char~ul~ ~ by three p~ the interle~ve factor, orr~ `e number of bytes in e~ch oc~iu~ ce of the stream, the o~fset, or the number of bytes into the info....-l;on field that the first byte of the stream occurs, S and the repeat factor--the offset bcl~cen the first byte of one occul,e. ce of the stream and the first byte of the next occulYellce of the stream. For ~A~"ple, in Figure 4, Stream 2's interlP~ve factor is two, its offset is one, and its repeat factor is two.
Providing for the eY~h~nge of digital real time data streams 10 ~t~cn various co.~.pQnf ntc of the host system and the tP1Pphone netwul!~ enables ih ~r~vol~ing of the host co"".u~r within a larger, possibly global, netwulk of CGnlpul~. Typical colll~ulel s~s~ ",s would include, but are not limited to, sound generation, audio r~or~.ng, video, and so on. In all cases, the host sul~s~", 15 data stream that e~ch~nges dah with the telecom adapter must be phase-synclllo,~iz~d with the telecom data stream.
A plOCC~duf~; for initi~li7~tirn and operation of the tPlP~om adapter by the host cG",~uler, to be describe~ plesenlly in relation to Figure 5, allows vide-area communi~tionc data strearns 20 obt~ined from analog t~PIephon~P lines to be conveniently manipulated and blended into the co",~u~r sound f~cilities~ for e~cample. Ihe host co."l)u~r cont~in~ signal ~f~ S~ g les~ui~s useful for g~l-at;o~ and d~P~tiQn of voice-band data signals (modem), speech gc~.lation, voice ~cog~ ;on, sound synt~PSi~
25 and the like. The pr~lu~e ensure that a precise integer Wo 94l27399 PCT/US94/04782 r~l~tionchip is ,..~ n~d between telecom data and the particular s~sy~tcnl of interestj such that the host intP~ s~lbsy~lll data stream is time-aligned with thé telecom adapter data stream.
Referring to Figure 5, the host co~p~ler system typically S employs a CISC (complex instruction set) microprocessor as the central p,ocessor (213). However, conte~polaly- CISC l,r~cessol~
by their nature lack suffici~-nt pnxes~;ng capacity to treat the digital telecom adapter datastream in real-time. For eY~mple, a V.32 analog modem signal could not be generated and delivered to the 10 tcle~l" adapter by the CISC CPU. Th~.efore, a Digital Signal ~ocessor (DSP) (205) is employed as a coprocessor to pelrol"~ the laborious but requisite signal tran~Ç.,l",ation colllput;~;on~ on the telecom data stream.
The DSP is a general purpose resource at the ~ l of 15 po~.ltially several host computer clients. The host co",~ ter o~ ;n~, system s~rlw~ th~erole employs a time-based sorlwdr~
s~h~--ling algo,itl"" to ensure its clients of re~col-~hle access to the DSP pr~s~ g ,~ soulces. The time-based scheduling concept is based on a list of tasks (206) that are defined by the host processor, 20 and e~uted in a sequential manner on the DSP. The time-base atomic unit is called a frame. For this reason the time-based s~ i~ system is also called a frame-based signal ~roceC~;,-g system.
wo g4l273gg 216iO~8 Operation of the telecom adapter is as follows. The bit-sy..cl,r~)nous clock (108) and bidire~tinnq-l datastreams are delivered to the host cG-,-puler on the serial interf~,ce (213). The serial data is clocked into a serial-to-parallel converter (211) according to the 5 trqnsitinn~ of the bit-synchronous clock. Since the datastream is req1tim~, continUQus~ and must be delivered reliably, regardless of tasks that may be running on the central pr~cessol (213), a deAi(~q~t~d Direct Memory Access (DMA) chqnnel (212) is used.
The DMA circuit moves data between the Telecom Sample Buffers 10 (210) and the telecom adapter.
At the same time, the DSP (205) may be ex~uting a parallel time-based task such as sound synthesis over the system speakers. In this case the speaker (210) is driven by a codec (207) from the sound sample buffers (209) which are filled as a result of 15 co...l~ul~;on~ made by the DSP. Again, since the datastream is realtime s~/"chr~nous, a DMA chqnnpl is deAi~qt~d to the sound system to ensure reliable transfer of the sound s~mrlos to the speaker.
In order to provide the reliable e~c-h-q-nge of sample data 20 between the host co-"puler sound system and the telecom adapter, the sound sample buffer must m-qintqin a fixed phase and time relqtion~hip with the telecom sample buffer. Note that, at the same time, the DSP op~lates according to a time-based schedllling alE,u~ ll. Th~efolt; the following procedure is implemented.
25 First, the telecom clock, which was previously shown to be bit-wo g4t273gg 216101~ -synchronous and in phase with the datastream delivered by the telecom adapter, is delivered to the host col,lpule~ USART (211) and a Phase-Locked Loop (203). The telecom data clock is used to synchronize the sound clock (201) which nominally operates at an 5 integer mllltiple of the telecom data clock. Thus the sound clock is phase-aligned with the telecom data clock.
The output of the PLL is then passed to a clock divider (204) which reduces the clock frequency to yield a periodic pulse.
This periodic pulse defines the DSP time frame and is used to 10 awaken the DSP and cause it to execute the task list. The tasks are eYe~utçd r~peliti-/ely according to the periodic pulse, which has a nominal period of ten milli~onds. Included in the tadsk list are the sound genc.dlion task(s), the telecom sample pr~cesC;,~ task(s), and a sample rate conversion task. The ~ullJo-ce of the sample rate 15 converter (211) is to transforrn the N samples found in the telecom sample buffer into M c~mplçs loaded into the sound sarnple buffer by the DSP. However, there must be a strict time ~ligr~mPnt beh.~cn the sound buffer and the telecom sample buffer.
Th~er~.~e, the telecom adapter is initi~li7~1 in precise reference to 20 the output of the clock divider (204).
The telecom adapter has a reset line (111) which is driven by the host colllyut~l. The reset line holds the telecom data and clock lines in a ql~ip-~nt state, when asserted. The clock line is activated, and sampling commences, when the reset line is de-25 asserted. A procedure illustrated in Figures 6-8 is executed by the wo 94l273g9 ~- 21 6lol8 t 12 ~;
System CPU (213) whereby the output of the clock divider is monilo,~d, such that the telecom adapter reset input is asserted and released at the a~propliale time to guarantee time-reference synchroni7~tion .
More particularly with reference to Figure 6, prior to time 1, the system CPU has already set up the DMA controller to start receiving data into the third sample of the receiver buffer where the DSP will expect to get the samples at the end of the 10 ms period.
The system CPU has set up the DMA controller to start tr~ncmitting data from the transmit buffer which has been initi~li7~d with two frames worth of null samples. When the system CPU
sees the 10 ms timer fire at time 1, it will active the reset (DTR) signal, bringing the telecom adapter out of the beacon phase and into operation. The telecom adapter will then grab the next receive sample from the codec and transmit it to the host, where DMA will place it into the receive buffer. The telecom adapter will then activate the Tx ~ndch~l~e line long enough to receive one sarnple from the host, which will be fed to the codec at the next c~mpling period. The telecom adapter will continue to exch~nge samples with the host in this way until the reset (DTR) signal is inactivated.
Each sample exc-h~nge consists of the telecom adapter se-rlding four receive bytes to the host and the telecom adapter retrieving four s~ bytes from the host, concicting of one sample for each of two çh~nn~,ls and two bytes per sample.
When the DSP receives a 10 ms intel.~p~ at time 2, there will be 80 receive samples in the receive buffer. The DSP
will block move these ~mpl~s into its own memory. The DSP
must skip every other sample in the buffer since both çll~nn~l's S s~mrl~s are in the buffer. Once the DSP has all the receive samples it will process these and produce transmit samples within 10 ms.
When the next 10 ms time goes off at time 3, the DSP will have placed the transmit samples in the transmit buffer 10 begin~ g with the first location after the initial 160 null samples.
The next time the telecom adapter and host exchange samples the real transmit sample will begin being sent. The maximum delay bel~n a receive sample and its c~lcsponding transmit sample will be two frame periods plus four sample periods, in this case 20 ms + (4*125~s) = 20.5 ms.
After the initi~li7~tion sequence is ex~uted, data is delivered from the telecom adapter to the host computer with both phase and time ~lignm~nt~ Thcçefolc the DSP, which is time edul~ for frame-based proceccing, is assured that the N telecom 20 ~mpllos, which arrive from the telecom adapter via the system DMA hardware, are entirely coincident with the gencl~tion of the M sound samples contitined in the sound sample DMA buffer.
The rorcgoing has described the principles, plefellcd embo~limentc and modes of operation of the present invention.
25 However, the invention should not be construed as limited to the wo g4l27399 - 2~ 6 ~ ~ 14 particular embo~im~-ntc licrucc~. Instead, the above-described ?1 embo~limentc should be regarded as illùstrative rather than restrictive, and it should be al,pr~'laled that v~ tionC may be made in those embotlirnentc by wolkels skilled in the art without S dcp~li~ g from the scope of the invention as defined by the following claims.
Claims (20)
1. A telecommunications adapter for inputting to a computer workstation a digital data stream representing a real time continuous analog signal, comprising:
means for receiving an analog signal and converting the analog signal to a voice-rate or greater digital data stream; and interface means for receiving the digital data stream and inputting the digital data stream to the computer workstation through a communications port of the computer workstation.
means for receiving an analog signal and converting the analog signal to a voice-rate or greater digital data stream; and interface means for receiving the digital data stream and inputting the digital data stream to the computer workstation through a communications port of the computer workstation.
2. A method of exchanging a digital real time data stream composed of data samples between a computer that performs frame-based signal processing in accordance with a timing signal derived from an internal clock and an analog communications network, using a telecom adapter that provides a clock signal to the computer and receives a control signal from the computer, comprising the steps of:
phase-locking the internal clock and the clock signal provided by the telecom adapter;
using the control signal, initializing the telecom adapter in timed relation to the timing signal derived from the internal clock; and performing frame-based signal processing of the data samples in accordance with the timing signal.
phase-locking the internal clock and the clock signal provided by the telecom adapter;
using the control signal, initializing the telecom adapter in timed relation to the timing signal derived from the internal clock; and performing frame-based signal processing of the data samples in accordance with the timing signal.
3. The apparatus of claim 1, wherein the means for receiving and converting comprises:
a telephone line connector;
an analog conditioning circuit connected to the telephone line connector; and a codec connected to the analog conditioning circuit.
a telephone line connector;
an analog conditioning circuit connected to the telephone line connector; and a codec connected to the analog conditioning circuit.
4. The apparatus of claim 3, wherein the means for receiving and converting further comprises:
a microcontroller connected to the codec; and a sample clock connected to the microcontroller.
a microcontroller connected to the codec; and a sample clock connected to the microcontroller.
5. The apparatus of claim 4, further comprising a handset connector connected to the analog conditioning circuit.
6. The apparatus of claim 5, wherein the interface means frames the digital data stream using time division multiplex framing so as to provide for a plurality of logical data streams.
7. The apparatus of claim 1, wherein the interface means comprises a universal synchronous/asynchronous receiver transmitter (USART).
8. The apparatus of claim 7, wherein the interface means further comprises:
a microcontroller connected to the USART; and a sample clock connected to the microcontroller.
a microcontroller connected to the USART; and a sample clock connected to the microcontroller.
9. The apparatus of claim 8, wherein the interface means further comprises a serial cable connected between the USART and the communications port of the computer workstation.
10. The apparatus of claim 9, wherein the serial cable includes a plurality of data lines connected to the USART and a clock line connected to the sample clock.
11. The apparatus of claim 10, wherein the serial cable further includes a reset line and a transmit handshake line, both connected to the microcontroller.
12. The apparatus of claim 11, wherein the microcontroller pulses the transmit handshake line to request data from the computer workstation on a byte-to-byte basis.
13. The apparatus of claim 11, wherein the microcontroller is responsive to deactivation of the rest line to transmit a series of bytes to the computer workstation and, in one-to-one correspondence thereto, to receive a series of bytes from the computer workstation.
14. A computing apparatus for receiving from a telephone adapter data samples representing a real time analog signal and for processing the data samples, comprising:
a communications port;
means for storing the data samples;
means for directly transferring the data samples from the communications port to the means for storing;
means responsive to a clock signal from the telecom adapter for deriving a lower-frequency clock signal; and digital signal processing means responsive to each occurrence of the lower-frequency clock signal to receive a predetermined number of data samples from the means for storing and for processing the predetermined number of data samples to produce processed data samples.
a communications port;
means for storing the data samples;
means for directly transferring the data samples from the communications port to the means for storing;
means responsive to a clock signal from the telecom adapter for deriving a lower-frequency clock signal; and digital signal processing means responsive to each occurrence of the lower-frequency clock signal to receive a predetermined number of data samples from the means for storing and for processing the predetermined number of data samples to produce processed data samples.
15. The apparatus of claim 14, wherein the communications port is a serial port including a USART.
16. The apparatus of claim 14, wherein the means responsive to a clock signal from the telecom adapter for deriving a lower-frequency clock signal includes a local clock and a phased locked loop.
17. The apparatus of claim 15, further comprising means for storing the processed data samples.
18. The apparatus of claim 17, wherein the local clock is a sound clock, and the means for storing the processed data samples is a sound sample buffer.
19. The apparatus of claim 18, further comprising a codec connected to the sound sample buffer.
20. The apparatus of claim 19, further comprising a speaker connected to the codec and means for directly transferring the sound samples from the sound sample buffer to the codec.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/078,890 US5495246A (en) | 1993-05-10 | 1993-05-10 | Telecom adapter for interfacing computing devices to the analog telephone network |
| US08/078,890 | 1993-05-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2161018A1 true CA2161018A1 (en) | 1994-11-24 |
Family
ID=22146829
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002161018A Abandoned CA2161018A1 (en) | 1993-05-10 | 1994-05-02 | Telecom adapter for interfacing computing devices to the analog telephone network |
Country Status (6)
| Country | Link |
|---|---|
| US (2) | US5495246A (en) |
| EP (1) | EP0698327A1 (en) |
| JP (1) | JPH09506721A (en) |
| AU (1) | AU6778994A (en) |
| CA (1) | CA2161018A1 (en) |
| WO (1) | WO1994027399A2 (en) |
Families Citing this family (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5495246A (en) * | 1993-05-10 | 1996-02-27 | Apple Computer, Inc. | Telecom adapter for interfacing computing devices to the analog telephone network |
| US5835787A (en) * | 1994-07-07 | 1998-11-10 | Lucent Technologies, Inc. | System for bi-directionally transferring a digital signal sample from a CODEC to a particular memory location and a second sample from memory to CODEC |
| US5727233A (en) * | 1994-08-02 | 1998-03-10 | Apple Computer, Inc. | Byte-mode and burst-mode data transfer mechanism for a high-speed serial interface |
| US5953674A (en) * | 1997-02-12 | 1999-09-14 | Qualcomm Incorporated | Asynchronous serial communications on a portable communication device serial communication bus |
| IL120370A0 (en) | 1997-03-04 | 1997-07-13 | Shelcad Engineering Ltd | Internet and intranet phone system |
| US6138190A (en) * | 1997-09-16 | 2000-10-24 | Cirrus Logic, Inc. | Analog front end and digital signal processing device and method |
| ES2136560B1 (en) * | 1997-09-16 | 2000-10-01 | Univ Madrid Politecnica | TELEPHONE LINE INTERFACE FOR THE DEVELOPMENT OF INTERACTIVE VOICE APPLICATIONS BASED ON RECOGNITION AND SPEECH SYNTHESIS. |
| US6029239A (en) * | 1997-12-01 | 2000-02-22 | Advanced Micro Devices, Inc. | Configuring a communications system with a configurable data transfer architecture |
| KR100697258B1 (en) | 1998-05-08 | 2007-07-09 | 삼성전자주식회사 | Computer system with modem |
| US6625208B2 (en) * | 1998-09-25 | 2003-09-23 | Intel Corporation | Modem using batch processing of signal samples |
| US6502138B2 (en) * | 1998-09-25 | 2002-12-31 | Intel Corporation | Modem with code execution adapted to symbol rate |
| US6661848B1 (en) * | 1998-09-25 | 2003-12-09 | Intel Corporation | Integrated audio and modem device |
| US6490628B2 (en) * | 1998-09-25 | 2002-12-03 | Intel Corporation | Modem using a digital signal processor and a signal based command set |
| US7051111B1 (en) * | 2000-04-25 | 2006-05-23 | Digeo, Inc. | Multiple source proxy management system |
| US7688803B1 (en) | 2000-09-01 | 2010-03-30 | Young Steven J | System and method for coordinating between multiple telephony channels |
| US7200859B1 (en) | 2000-11-22 | 2007-04-03 | Digeo, Inc. | Apparatus and method for intelligent multimedia compression and distribution |
| US6813643B2 (en) | 2001-01-05 | 2004-11-02 | Digeo, Inc. | Multimedia system with selectable protocol module including MPEG logic and docsis logic sharing a single tuner |
| US20020114360A1 (en) * | 2001-02-20 | 2002-08-22 | Perlman Stephen G. | System and method for processing multiple broadcast multimedia streams |
| US20020116705A1 (en) * | 2001-02-20 | 2002-08-22 | Perlman Stephen G. | System and method for processing conditional access data |
| US7046805B2 (en) * | 2001-03-20 | 2006-05-16 | Digeo, Inc. | System and method for efficiently storing and processing multimedia content |
| US7093277B2 (en) * | 2001-05-30 | 2006-08-15 | Digeo, Inc. | System and method for improved multi-stream multimedia transmission and processing |
| US7386129B2 (en) * | 2001-05-30 | 2008-06-10 | Digeo, Inc. | System and method for multimedia content simulcast |
| US7463737B2 (en) * | 2001-08-15 | 2008-12-09 | Digeo, Inc. | System and method for conditional access key encryption |
| JP4136601B2 (en) * | 2002-10-30 | 2008-08-20 | 三菱電機株式会社 | Transceiver module |
| DE10353500B4 (en) * | 2003-11-11 | 2005-09-08 | Siemens Ag | Method and device for synchronizing data transmission between data pumps |
| GB2431839B (en) * | 2005-10-28 | 2010-05-19 | Sony Uk Ltd | Audio processing |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4602127A (en) * | 1984-03-09 | 1986-07-22 | Micro Processor Systems, Inc. | Diagnostic data recorder |
| JPH04506131A (en) * | 1988-10-10 | 1992-10-22 | エスエムハー マネージメント サービシーズ アクチェンゲゼルシャフト | Multipurpose communication device |
| FR2652173B1 (en) * | 1989-09-15 | 1994-05-06 | Apple Computer Inc | MODULATOR / DEMODULATOR DEVICE WITH VARIABLE CONFIGURATIONS FOR COMPUTER OR THE LIKE. |
| US5305312A (en) * | 1992-02-07 | 1994-04-19 | At&T Bell Laboratories | Apparatus for interfacing analog telephones and digital data terminals to an ISDN line |
| US5495246A (en) * | 1993-05-10 | 1996-02-27 | Apple Computer, Inc. | Telecom adapter for interfacing computing devices to the analog telephone network |
-
1993
- 1993-05-10 US US08/078,890 patent/US5495246A/en not_active Expired - Lifetime
-
1994
- 1994-05-02 WO PCT/US1994/004782 patent/WO1994027399A2/en not_active Application Discontinuation
- 1994-05-02 AU AU67789/94A patent/AU6778994A/en not_active Abandoned
- 1994-05-02 JP JP6525495A patent/JPH09506721A/en active Pending
- 1994-05-02 CA CA002161018A patent/CA2161018A1/en not_active Abandoned
- 1994-05-02 EP EP94915961A patent/EP0698327A1/en not_active Withdrawn
-
1995
- 1995-06-07 US US08/477,548 patent/US5631651A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| US5495246A (en) | 1996-02-27 |
| EP0698327A1 (en) | 1996-02-28 |
| JPH09506721A (en) | 1997-06-30 |
| US5631651A (en) | 1997-05-20 |
| WO1994027399A3 (en) | 1995-04-06 |
| AU6778994A (en) | 1994-12-12 |
| WO1994027399A2 (en) | 1994-11-24 |
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