Apple Computer Inc. v. Burst.com, Inc.

Filing 116

Declaration of Leeron Kalay in Support of 115 Reply Memorandum In Support of Motion for Summary Judgment of Invalidity filed byApple Inc.. (Attachments: # 1 Exhibit A# 2 Exhibit B# 3 Exhibit C# 4 Exhibit D# 5 Exhibit E# 6 Exhibit F)(Related document(s) 115 ) (Brown, Nicholas) (Filed on 6/21/2007)

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Apple Computer Inc. v. Burst.com, Inc. Doc. 116 Att. 5 Case 3:06-cv-00019-MHP Document 116-6 Filed 06/21/2007 Page 1 of 6 Exh. E Dockets.Justia.com Case 3:06-cv-00019-MHP IEEE 'l'R:\NS.\C'l'IONS ON COMMUNIC.\TION TECHNOLOGY Document 116-6 Filed 06/21/2007 VOL. COM-14, NO. Page 2 of 6 OCTOBEI~ 5 1966 Transmission Facilities for General Pumose Wideband Services on Analog Carrier Systems J . Absiraci-Three newgeneral purpose wideband data facilities provide for the transmission of synchronous and nonsynchronous, 2-level data a t bit rates rangingfrom 19.2 to 250 kb/s.These facilities make use of half-group, group, and supergroup bandwidth telephone facilities. The majorcomponents involved are the type 303 wideband data station, the exchange area transmission systems (local loop, N-Carrier, TI Carrier), and the long-haul transmission systems [L-type multiplex (LMX) terminals, and coaxial cable and microwave radio circuits]. The group band system is representative and is discussed in some detail. The analog carrier systems were designed principally to handle voice frequencytransmission and they present special problems when they are adapted to accommodate wideband signals. For example, up to eight LMX group connector filters may be encounteredina 4000 mile circuit and each connector introduces over 150 ps of delay distortion in the transmission band. Special delay equalizers are added to each connector which reduce the distortion to f3 ps in the band 64 to 104 kHz. The modulation schemes utilized in the various wideband modems were carefully tailored to the respective carrier systems. The LMX modem, usedasan example in this paper, utilizes vestigial sideband, suppressed amplitude carrier, modulation. A carrierfrequency pilot is added to thetransmitted signal to facilitatecarrier recovery in the receiver. The pilot isseparated fromthe wideband signal in the receiver by acrystal bandpass filter. The filtered pilot isused for two functions; it isused to control an AGC circuit and hence the level of the received signal, and it is used in amultiple loop APC circuit to coherently demodulate the wideband signal. The APC circuit is new and promises improved performance over the conventional phase-locked oscillator when used inacoherentdetector. It is capable of maintainingsmaller phase errors in the presence of phase perturbations and, furthermore, the recoveredcarrier is always a t exactly the correctfrequency and hence the circuit is incapable of breaking lock. ity of 250 kb/s, full-group, which can handle up to50 kb/s, and half-group, capable of 19.2 kb/s operation. These systems aredesignated general p w p o s e in that they can handle synchronous or nonsynchronous, 2-level data at any bit speed up to their respective design maxima. Furthermore, the transmission facilities described in this paper are analog and can accept any signal that falls within their signal spectrum and power handling capabilities [I]. TI~ANSMISSION FACILITIES T Figure 1 shows a possible coast-to-coast wideband connection, although all carriersystemsdo not necessarily appcarin one circuit [2]. The type 303 data set transmitterattenuates t,he low-frequency components in the 2-level data signal by means of a simple high-pass filter. The low-frequency components are reinserted at the data set receiver byaregenerativefeedbackcircuit [3]. The consequent reduction in lowfrequency content in the transmitted signal alleviates low-frequency transmission requirements. A baseband repeater system (local loop) is available which permits transmission of the restored polar line signal over ordinary pairsin telephone cable. The local loop is currently used for wideband transmissionup to 20 miles, although most circuits are less than 10 miles in length. The N-Carrier transmission system (Fig. 1) is used on short-haul routes up to 200 miles. The N-Carrier wideband terminals, as well as those for L-Carrier and T1 Carrier, incorporate modulation schemes that are carefully tailored to the facilities. The bandwidth of the N-Carrier line is INTRODUCTION sufficient,for half-group or full-group wideband service, but HE ANALOG carrier systems that play a prominent is insufficient forsupergroup service. Thelatter is rerole in the transmission of wideband (data) signals in stricted to the use of a baseband local loop or T1 Carrier the Bell System are theN-Carrier for short-haul transmis- for exchange area transmission. The TI Carrier system utilized pulse code modulation sion and -the L-Multiplex for coast-to-coast transmission. and time-multiplexing techniques to provideshort-haul Local loops, which interconnect the dataset on the customer's premises and the centraloffice equipment, make use of transmission of 24 voice frequency signals. The system has speed of 1..544 mb/s. New wideband ordinary pairs in the telephone cables. In addition, there is asynchronousbit a ncw digital time-multiplexed transmission system, T1 the Carrier, that is used for exchange area service. The anaCOAXIAL CABLE LOCAL LOW N-CARRIER ILMXl log facilities were designed principally tohandle voice I\\ transmission, and they present special problems whenthey TOLL TOLL OFZlCC OFFICE are adopted to acconmlodate wideband signals. Threedistinctgeneralpurposewideband services are available: supergroup, having a maximum channel capac- -- Manuscript received January 26, 1966; revised May 27, 1966. Paper CP66-1031 presented a t t h e 1966 IEEE International Convention, New York, N. Y. The author is with the Bell Telephone Laboratories, Inc., North Andover, Mass. 655 OFFICE OFFICE Fig. 1. Wideband transmission circuit. Case 3:06-cv-00019-MHP 656 Document 116-6 Filed 06/21/2007 Page 3 of 6 IEEE C T O B E R C T IT E CS ON L O G YM U N I C A T I O N O TRANSA ON HNO COM terminals permit it to handle either eight 50-kb/s or two 250-db/s data channelsin place of the voice channels [4]. The half-group data service: is in a format that is not readily handled by the T1 Carrier [ 3 ] . The long-haul transmission plant is made up of LMX terminals together withrepeatercd coaxial cables and pointto-point microwave radio chancds. The terminals include several steps of single sideband, suppressed carrier, amplitude modulation.Twelve voice channels which are normally multiplexed in a group band extending from 60 to 108 kHz can be replaced with either two half-group wideband channels or one full-group channel. Five group channels aremodulatedintothe supergroupband andten supergroups are combined in a mastergroupband. The 250 kb/s service replaces five grllup channels and operates directly into the 312 to 552 kHzsupergroupband. The variousradiosystemscarry one to three mastergroups; the L3 Carrier multiplexes thret: mastergroups into a 7.97 MHz band; and, shortly, L4 Carrier will introduce a 16.98 M H z broadband channel composed of six mastergroups. The type 303 data service involves only the group and supergroup bands, but the signa,ls can be multiplexed into any position in the L3, L4, or ra,dio spectra. The restored polar line signal is recovered at the output of each of the transmission facilities depicted in Fig. 1. Thus, the type 303 data set can operate directly into any one of them, and, furthermore, the order of interconnection of the various systems is unimportant. The modulation techniques utjlized in the various widebandmodems were carefully sselected for optimum performance considering the particular data service and carrier facility involved. Each combination generates unique problems and constraints. The I M X group-band terminal is representative, however, and itherefore the remainder of the paper will be devoted to a discussion of this system. LMX GROUP BAND SYSTEM represents the relative envelope delay of the terminal receiver and transmitteralone and thelower delay cha,racteristic is of the group connector filter. The total relative envelope delay distortion (consisting of the sum of the two characteristics in Fig. 3 ) is indicated by the dotted curve in Fig. 4. The delay equalizer that is added to each connector reduces the distortion to approximately . t 3 ps as represented by the solid curve. A new connector and equalizer have recently been designed that will further improve the equalization to +1.5 ps per link so that the residual delay distortion will be =t12 ps for a typical 4000 mile circuit. 50 kb Wideband Modem Channel ChaTacteristics The 50 kb modem basebandchannelcharacteristic is shown in Fig. 5. It is designed to have a 50 Hz to 37 kHz, nearlysquarebandandallin-bandshaping is donein the type 303 data set [3]. The square band characteristic Fig, 2. LMX terminal and 1ocal.loop modifications for wideband servlce. Wideband Equipment The new equipment that has to be added to a LMX circuit to adapt it for data transmission is shown in Fig. 2. The upperdiagramdepictsastandard voice circuit consisting of a telephone set, local cable pairs, LMX terminals, and coaxial cable an'd microwave facilities. I n the lower figure, the system has been adapted for 50 lib wideband service. The 303 data set requires an additional cable pair to provide 4-wire transmission.' Special amplifiers and loss equalizers are spliced into the local cable to adapt it for wideband signals. .At the telephone office, a data transmitter and receiver (wideband modem) are added to modulate the restored polar line signal into the group band. FinaIly, special delay and loss equalizers are added a t connector points to correct the delay and attenuation distortion introduced bythe LMX bandpass filters. The delay distortion introduced by the LMX terminal equipment, is depicted in Fig. 3 . The upper characteristic A voice frequency coordination channel accompanies every standard wideband channel and requires two additional cable pairs not shown in the figure. DELAY u-sEc LMX R E C E I V E R A N D T R A N S M I T T E R R E LE N VVDL O P E A T I EEL L A Y FREQUENCY - K H z '"T DELAY 100 U-SEC \ 60 GROUPCONNECTOR RELATIVE ENVELOPE DELAY 1 100 m 80 90 IUB FREQUENCY -KHz Fig. 3. Delay a t junctions between LMX systems. DELAY EQUALIZED GROUP BAND 7 60 70 80 90 100 18 0 FREQUENCY-kHz Fig. 4 Residual delay distortion of the group band for one link of . LR4X. Case 3:06-cv-00019-MHP 1966 ON SERVICES WIDEBAND RONNE: Document 116-6 Filed 06/21/2007 Page 4 of 6 657 ANALOG CARRIER SYSTEMS permitsseveralmodems to be connected intandem if desired. The high-pass filter located in the type 303 data set transmitter shapes the spectrum low frequencies and at a rolloff network in the data set receiver shapes the highfrequencyband. The group band data channel after modulation is shown inFig. 6. The wideband nlodem for the LMX system incorporates vestigial sideband, suppressed carrier, amplitude modulation with coherent demodulation [5]. Vestigial sidebandoperationpermitsoptimumutilization of the availablebandwidth. Suppressing the carrierresults in maximum signal-to-noise performance since the LMX system is both total-power and single-tone limited [a]. The basic group extends from 60 to 108 kHz. The available CHANNEL CHARACTERISTIC bandwidth is somewhat restricted by a 104.08 kHz pilot tone which is used for automatic gain regulation of the LMX broadband terminals. The frequency band between the pilot and the 108 kHz band edge is available, however, for the voice frequency coordinationchannel. The wideband modem carrier frequency is 100 kHz, which divides the band into a 4 kHz vestigial upper sideband and a 37 kHz lower sideband, resulting in an equivalent baseband of 37 kHz. 0 I 0 25 kHz 37kHz Fig. 5 . Baseband 50 kb/s channel. VOICE FREQUENCY CHANNEL 4kHz VESTIGIAL SIDEBAND 7 1 6OkHz WIOEBANO CARRIER FREQUENCY Fig. 6. Group frequency 50 kb/s channel. YF IN ~ I Wideband Transmitter A block diagram of the transmitter is shown in Fig. 7. The baseband signal first passes through a line equalizer and low-pass filter. The line equalizer can be adjusted to compensate for variations in the loss and delay slope of the intra-office wiring. The low-pass filter limits the noise bandwidth and suppresses high-frequency signal components which would cause frequency foldover upon modulation. A crystal-controlled oscillator generates a 200 kHz sine wave which is then divided to 100 kHz by a single stage counter. I n this way a square wave carrier is generated with a precise 50 percent duty cycle for modulating the wideband signal. The carrier drives a balanced, two transistor, product modulator. The signal at the output of the modulator is double sideband, amplitude modulated. Power in the vicinity of the carrier frequency is small because of the high-pass filtering carried out in the data set. A carrier frequency pilot tone which is in-phase with the modulating carrier is added to the modulated signal at a power 9 dB below the average power in one sideband. The bandpass filter following the modulator passes the lower sideband and a 4 kHz vestige of the upper sideband. The filter suppresses all modulation products that fall outside the data channel toprevent interferencewithadjacent group channels that are multiplexed on either side of the wideband channel. The signal is then delay and loss equalized and combined with the voice frequency coordination channelfortransmission over the LMX facilities. The equalizer corrects the delay and amplitude distortion introduced by all transmission networks in the transmitter and receiver and also for the residual delay distortion in one link of LMX. Wideband Receiver A block diagram of the wideband receiver is shown in Fig. 8. The voice frequency and wideband signal are first ,separated by bandpass filters for demodulation. The receiving bandpass filters also limit the noise bandwidth and preventadjacentchannelsfrominterferingwiththe received signals. The 100 kHz carrier pilot is separated from the data signal by a narrow band crystal filter. The pilot is used to control the gain of the receiving amplifier and hence the power level of the received signal. The AGC circuit is fastactingto supplement the slow-acting regulators of the LMX terminals. Impairments due to signal level variations arise in two ways: 1) if the signal level is allowed to drop at the input of alink, the S/N ratio in that link will be reduced, and 2) a signal level variation at the input Fig. 7. Fifty kb/s wideband transmitter. IOBkHz CARRIER . - VF OUT SIGNAL Fig. 8. Fifty kb/s wideband receiver. Case 3:06-cv-00019-MHP 655 Document 116-6 Filed 06/21/2007 Page 5 of 6 lEEE 'l'H.\NS:\CTIONS OCTOBER TECHNOLOGY ON COMMUNICA'I'ION of a slicer is equivalent to a variation in theslice level and hence a decrease in noise immunity. The filtered 100 kHz pilot is slso used as a carrier to coherently demodulate the wideband signals. Phase errors introducedby the crystal pick-off <filter and associated circuits are corrected by a volt,agc!-controlledphase shifter. The error voltage tthat controls the phase shifter is generated by a detector in which the phase of the recovered carrier and the phase of the received carrier pilot are compared. This form of APC circuit has been called SL phaselocked filter. The demodulated dat,a signal is passed through a lowpass filter to suppress unwanted modulation products and then amplified to the required interface power level. A small attenuation andslope equalizer is used to compensate for intraoffice wiring similar to thatin the transmitter. The closed loop transfer function, @c(~)/cD,(~), the and transfer characteristic of phase error relative toinput, phase jitter, @ . , ( U ) / ~ ~ ( W )are also given in Fig. 9. These ex, pressions emphasize the principle characteristics of the phase-locked filter. The circuit response is not significantly influenced by the bandwidth of the crystal filter, providing the filter bandwidth is small compared to the loop bandwidth. The gain constant K can generally be selected on the basis of constant phase error requirements (due to frecluency offset) permitting an independent optimization of the transient response in terms of G(u), the low-pass filter characteristic. It is desirable to maintain the peak phase error of the recovered carrier resulting from phase jitter below approximately 5degrees so that thetransmission impairment from this source be insignificant>131. Some idea of the amount of transmission phase jitter that can be tolerated may be Coherent Demodulaior obt.ained bycalculating the phaseerrorresulting from The design of an APC circuit for use in a coherent de- sinusoidal input phase jitter at various frequencies and modulator poses some interesting problems. For example, amplit,udes. The magnitude of the sinusoidal input jitter funcsince the average power of the group band data signal is 9 is plotted in Fig. 10 (for a representative circuit) as a tion of the frequency of the input jitter that results in a dB above the level of the ca,rrier pilot,, it is a potential source of interference i n the carrier recovery circuit. The peak phase error of 5 degrees. This characteristic is for a phase-locked filter with a loop bandwidth, (1 K ) fi, of interference of data signals i:j nlinimized by transmitting the carrier pilot at thesame phase as that used for 1000 Hz. Note that the permitted frequency of the input jitter mustgenerally be much less than theloop bandwidth modulation. For proper operation, the phase detector carrier must be it1 quadrature with the pilot, and, therefore, if the phase error is to be maintained below the 5-degree the d a h components near the carrier are suppressed in the boundary. phase detector by phasecancellation. This condition is enhancedbymaintainingflattransmissionthrough the ,-PHASESHIFTER vestigial region in the transmitter andplacing the vestigial shaping network at the input of the data demodulator in the receiver. The signal energy t,hat falls outside the double sideband region is suppressed by a low-pass filter located at the outputof the phase detector. The commonly used circuit for carrier recovery is the phase-locked oscillator, consisting of a voltage-controlled *,-PHASE OF REFERENCE oscillator in a feedback loop. It suffers from an inherent CLOSED LOOP GAIN CARRIER PILOT ecmPHASEOFCARRIER narrowbandwidth.This att,ribu.te can oftenbe used to _ . %+KG(-I ecw %("I 4 0, .PHASE ERROR +KG(*l advantage when phase averaging or smoothing is required, H1(-1*100 KHz BPF PHASE ERROR RESPONSE EPUIVALENT LOW CHAR. but can contribute excessive signal impairment when used GIw)*LP.FCHAR. in a wideband modem. The carrier-recovery circuit should be capable of tracking faithfully the short-term as well as the long-term phase perturbations introduced by broadthe Fig. 9. Equivalent circuit of phase-locked filt,er. band facilities [2]. The phase-locked filter exhibits no inherent band limiting characteristic and in princip'le can be made to track phase perturbations of any desired frequency and amplitude faithfully. (In practice the bandwidth of the control loop must be limited to restrict thenoise bandwidth.) The equivalent linear circuit forthe phase-locked filter is given i n Fig. 9. This equivalent circuit is valid for phase errors less than about 30 degrees2but this in way restricts the no amplitude or frequency of the input phase perturbations I that, canbe considered. o io 160 1. 50 200 250 + I FUSS INPUT JITTER FREWENCY. li.HZ This restriction results from the use of a phase detector with a sinusoidal transfer characteristic ratherthan one wit.h a linear characteristic as assrlmed in Fig. 9. Fig. 10. Magnitude of sinusoidal input jitter, producing a peak phaseerror of 5", as a function of jitter frequency fi. Case 3:06-cv-00019-MHP Document 116-6 Filed 06/21/2007 Page 6 of 6 coNcLusloN The telephone carrier systems werc originally designed for voice frequency transmission but have proven adaptable to high-quality wideband service. This has been accomplished by the careful selection of a general data format (restoredpolar)and of modulation schemes tailored for each of the facilities. This paper describes the wideband terminal equipment designed for the LMX group band. Other signal processing schemes are required for the wideband terminals designed for the X-carrier and TI Carrier facilities. The phase-locked filter promises improved performance over the phase-locked oscillator when used in a coherent demodulator. It is not only capable of maintaining smaller phase errors in the presence of phase perturbations but the recovered carrier is always a t exactly the correct frequency and hence the circuit is incapable of bf,eakinglock. LOSS of pilot automatically shuts off the receiver, preventing tlhe generation of unintelligible signals due to noncoherent demodulation. REFERENCES [ l ] 11. T . James, "The evolution of wideband services in the U~ril,ed States," this issue, pp. (736-640. [2] J., J. Mahoney, Jr., Transmission plan for general purpose wtdeband services," this issue, pp. 641-648. [ 3 ] R.. 11. Fracassi and F. E. Froehlich, "A wideband data station," this i s s ~ epp. 648-654. , [4] R. Tarbox, "T1 carrier transmission systems for general purpose wideband services." 1966 I E E E Intemat'l Conv. Rec., pt,. 1, pp. 210-218. [5] F. K. Becker, J. R. Davey,and B. R. Saltzberg, "An A M vestigial sideband data transmission set using synchronolts detection for serial tmnsmission up to 3,000 bit,s per second," i l I E E Trans.(Communication and Electronics), vol. 81, ptj. I, Concise Papers The Covariance of the Frequency of a Narrowband Gaussian Random Process When tshe multiplicative disturbalrces of the channel are modeled as a random, time-variant linear filter, with a time-variant transfer function that is a realization of a zero-mean, Gaussian random field [ 3 ] ,the channel output is a realization of a zero-mean, nonstat,ionary, Gallssian random process. The resttlts given here are directly applicable to a F M system wing s11ch a channel. The complex representation [4]-[6] is used for all narrowband Gaussian random processes throughout this note, thus all narrowband Gaussian random processes are zero-mean and jointly circularly complex, i.e., Abstract-The mean and covariance of theinstantaneousfrequency of a narrowband, zero-mean, stationary, Gaussian random process are found when the quadrature components of the process areidenticallydistributed.Whenthe quadrature componentsare stationaryand statistically independent, the mean andcovariance expressions are identicalto well-known expressions. The mean and covariance of t,he instantaneous freqllency of a narrowband, zero-mean, stationary Gaussian random process have been found by Lawson and Uhlenheck [ l ] ,and Rice [2], Ilnder t,he const.raint that the quadratmure components: of t,he process are st,at.istically independent and identically distributed.Another method of finding the mean and covariance of the instantaneous frequency of a zero-mean, narrowband, Gaussian random process is presented here. The process need not be st,ationary, and the qnadrature components need not, be statistically independent,; however, the quadrat,nre components must be ident,ically distributed. When t,he process is not stationary, or t.he quadrature component,s are not, st.atist,ically independent, t,he covariance of the frequency contains a term that is not, present in Lawson and Uhlenbeck's [ I ] or Rice's [2] expressions. The mean and covariance of the inst,antaneous frequency are of int,erest in the analysis of F M systems t,hat, use a fading channel. I\iIanuscript received April 14. 1966; revised June 15, 1966. This paper presents renearch Derformed while the author was witkthe Communication Laboratory of ~. Stanforditesearch Institute. The author is with the Department of Electrical Engineering, Cornell University, Ithaca, N. Y . ~ E [ z ( t ) ]= 0 and E [ z ( ~ ) ! / ( u =] 0. ) (1) The statistics of two such processes are thlls cornplelely det.ermined by the cross-covariance fnnction czb,(t,u)= EML)Y*(?L)I and the two auto-covariance functions c.(t,u) = E [ z ( t ) z * ( u ) ] and cY(l,u) = E[u(l)y*(u)]. (2) (#) [The well-known expectation operator is E [ . ] and y* is the complex conjugate (and transpose, if appropriate) of 11.1 Other well-known properties of the complex representation are that the magnit,nde of the complex representation Iz(t)l is the envelope of the narrowband process, andthatthe phase of the complex representat,ioll + [ z ( t ) ] is the phase of the narrowband process. This note is also concerned with s(t), the instantaneous complcx frequency of a process, which is defined as the derivative, wit,h respect to time, of t,he natural logarithm of t.he process s ( t ) a- In[z(t)] = Ih[z(t)] = $(t)/z(t). a at (4) 659

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