~IEEE TRANSACTIONS ON
`A
`I
`
`SEPTEMBER 1971
`
`VOLUME BC-17
`
`NUMBER 3
`
`Published Quarterly
`
`EDITOR'S NOTE .
`
`PAPERS
`
`Broadcasting: Evolution of Policy .
`
`Setting FCC License Fees According to Frequency Spectrum Utilization: A Suggestion ..
`
`Three-Channel FM Stereo Multiplex System for Compatible Broadcasting ...
`
`The Vertical Interval: A General-Purpose Transmission Path ..
`
`The Measurement of Short-Time Waveform Distortion in NTSC TV Facilities ..
`
`R. M. Morris
`
`61
`
`. C. T. Whitehead
`
`D. W. Webbink
`
`S. W. Halpern
`
`T. V. Anderson
`
`. H. Schmid
`
`62
`
`64
`
`70
`
`77
`
`83
`
`APPLE EX. 1020
`Page 1
`
`

`
`IEEE BROADCASTING GROUP
`
`The Broadcasting Group is an organization, within the framework of the IEEE, of members with principal professional interest in broadcast·
`ing. AU members of the IEEE are eligible for membership in the Group and will receive this TRANSACTIONS upon payment of the annual mem(cid:173)
`bership fee of $3.00. For information on joining, write to the IEEE at the address below.
`
`A. H. LIND, Chairman
`
`M. BURLESON
`L. B. DAVIS
`A. P. EVANS, JR.
`E. GRAHAM, JR.
`
`ADMINISTRATIVE CO.MMITIEE
`H. T. HEAD, Vice Chairman
`
`M. BURLESON, Secretary-Treasurer
`
`H.T.HEAD
`W. R. Hoos
`J. JoNES
`H.L.KASSENS
`
`R. E. LEACH
`H. T. LIND
`E. N. LUDDY
`
`E. L. SHUEY
`A. TAYLOR
`W. WHALLEY
`F. ZELLNER
`
`Ex Officio
`
`G.KUNK
`R. M. MoRRIS
`
`0. L. PRESTHOLDT
`R.A.ToWN
`
`IEEE TRANSACTIONS~ ON BROADCASTING
`
`ROBERT M. MoRRIS, Editor
`
`THE INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, INC.
`
`Officers
`
`JAMES H. MULLIGAN, JR., President
`RoBERT H. TANNER, Vice President
`HAROLD CHFsrNur, Vice President, Technical Activities
`
`CLARENCE L. CoATES, JR., Vice President, Publication Activities
`JOHN R. WHINNERY, Secretary
`RAYMOND W. SEARS, Treasurer
`
`Headquarters Staff
`
`JoHN L. CALLAHAN, Staff Consultant
`ELWOOD K. GANNETT, Director, Editorial Services
`WILLIAM J. HILTY, Director, Convention and Publishing Services
`WILLIAM J. KEYES, Director, Administrative Services
`JOHN M. KINN, Director, Educational Services
`LEON PoDOLSKY, Staff Consultant
`
`DoNALD G. FINK, General Manager
`CHARLilS F. STEWART, JR., Director, Member Services
`BETTY J. STILLMAN, Administrative Assistant to the General Manager
`RICHARD M. EMBERSON, Director, Technical Services
`EDWIN D. MACDoNALD, Conference Services
`SAVA I. SHERR, Standards
`
`Editorial Department
`
`H. JAMES CARTER, Managing Editor, Transactions
`
`Senior Editors: ANDREE ABRAMOFF, ANN H. BUROMEYER, CAROLYNE BLENOWITZ, GAIL S. FERENC
`Associate Editors: NANCY B. BuDDE, HELENS. GoLDMAN, MARILYN SALMANSOHN, NANCY VIGGIANO
`
`IEEE TRANSACTIONS ON BROADCASTING is published quarterly by The Institute of Electrical and Electronics Engineers, Inc., 345 East 47 Street,
`New York, N. Y. 10017. Responsibility for the contents rests upon the authors and not upon the IEEE, the Group, or its members. This journal
`is available in either microfiche or printed form. Individual copies may be purchased at $2.50 (first copy only) to IEEE members and $5.00 per copy
`to nonmembers. Annual subscription price: IEEE members, dues plus Group fee. Price for nonmembers available on request. Abstracting is per(cid:173)
`mitted with mention of source. All rights, including translation, are reserved by the IEEE. Requests for republication permission should be ad(cid:173)
`dressed to the IEEE Editorial Department, 345 East 47 Street, New York, N.Y. 10017. Copyright© 1971 by The Institute of Electrical and
`Electronics Engineers, Inc. Printed in U.S.A. Second class postage paid at New York, N.Y., and additional mailing offices.
`
`APPLE EX. 1020
`Page 2
`
`

`
`IEEE TRANSACf!ONS ON BROADCASTING, VOL. BC-17, NO. 3, SEPTEMBER 1971
`
`77
`
`during a three-channel transmission above that which
`is observed in a two-channel receiver during a two(cid:173)
`channel transmission.
`In the above a nalysis, the output peak S/ N ratio was
`defined as the ratio of the peak output signal power in
`the absence of noise to the mean output noise power in
`the presence of an unmodulated carrier [8 ].
`
`AcKNOWLEDGMENT
`The a uthor would like to express his sincere apprecia(cid:173)
`tion toM. J. Gans, W. C. J akes, Jr., B. R. Davis, and
`F. K. Harvey for their many helpful conversations and
`generous encouragement. H e would also like to thank
`B. A. Stevens for his extensive literature search of this
`subject.
`
`REFERENCES
`[1] J. P. Meure, "Four-channel st~reo FM-from one station," High
`Fidelity, vol. 20, Mar. 1970, pp. 72- 73.
`[2] G. D . Browne, "A pulse time multiplex system for stereophonic
`broadcasting," J. Brit. Inst. Radio Eng., vol. 23, Feb. 1962,
`pp. 129-137.
`[3] D. G. Fink, Television Engineering. New York: McGraw-Hill,
`1952, pp. 544-549.
`[4] J. C. Steinberg and W. B. Snow, "Symposium on wire transmis(cid:173)
`sion of symphonic music and its reproduction in auditory perspec(cid:173)
`tive: Physical factors," Bell Syst. Tech. J., vol. 13, Apr. 19.34,
`p. 257.
`[5] M. Gerzon, "Quadrature ambience with reference tone," Radio
`Electron., Dec. 1970, pp. 52, 53, 58.
`[6] P. F . Panter, Modulation, Noise and Spectral A nalysis. New
`York : McGraw-Hill, 1965, p. 161.
`[7] N. Parker and D. W. Ruby, "Some notes on t he calculation of the
`S/N ratio for a FM system employing a double-sideband AM
`multiplex signal," IRE Trans. Broadcast Telev. Receivers, vol.
`BTR-8, Apr. 1962, pp. 42-46.
`(8] M. Schwartz, Infprmation Transmission, Modulation, and Noise..
`New York: McGraw-Hill, 1970, p. 472.
`
`The Vertical Interval: A General-Purpose
`Transmission Path
`
`TED v. ANDERSON, ASSOCIATE MEMBER, IEEE
`
`Abstract-Equipment is now available to utilize the vertical in(cid:173)
`terval of the television signal to transmit digital information. A verti(cid:173)
`cal interval (VI) encoder selects any line, 13 through 20, onto which
`is clocked the data originating from a character generator, computer
`or other digital device. At the receiving point, data are decoded for
`display in "real time" using a character generator, printed out in hard
`copy, or used to initiate electromechanical operations through proper
`interfaces.
`Numerous applications exist for VI transmission: transmitting
`information to network affiliates, newswire distribution, remote
`computer access, centralized clock system control, remote control of
`VTR's and video switchers, and test signal transmission.
`
`INTRODUCTION
`
`H ISTORICALLY the vertical blanking interval
`
`has been utilized by television networks and
`common carriers to transmit video test signals.
`Equipment is now available that further permits the
`addition of digital information from character genera(cid:173)
`tors, computers, and other sources onto the vertical
`interval.
`Fig. 1 shows a picture of the vertical interval with
`data encoded on line 16. Note the equalizing pulses,
`vertical serration, and the beginning of the horizontal
`
`Manuscript received October 29, 1970 ; revised May 21, 1971.
`This paper was presented at the 1970 IEEE Broadcast Symposium,
`Washington, D. C., September 25, 1970.
`The author is with TeleMation, Inc., Salt Lake City, Utah.
`
`Fig. 1. Vertical interval with data encoded on line 16.
`
`lines that occur during vertical blanking. As you know,
`each television line is equal to 63.S J.lS. About SO J.lS of
`each line is used to handle the data. To determine the
`theoretical maximum amount of time or space available
`during the vertical interval, subtract line 13 from line
`20, equalling 7 lines: 7 X SO gives us 3SO J.lS, the total
`time available.
`The practical limit in handling raw data is about 40
`bits per horizontal line; however, by means of modula(cid:173)
`tion tech niques, we can easily have 160 bits per hori-
`
`APPLE EX. 1020
`Page 3
`
`

`
`78
`
`IEEE TRANSACllONS ON BROADCASTING, SEPTF.MBER 1971
`
`SHIFT REGISTE R
`
`ENCODER I DECODER
`
`l
`
`CUST OM ER
`DIGITAL EQU IPMENT
`
`Fig. 2. Vertical interval encoder/ decoder system.
`
`• •
`
`GATE $AI- OATA GAtH
`
`Fig. 3. TVI-100 Vertical Interval Encoder / Decoder.
`
`DATA
`
`D
`
`CLOCK OUT
`.....ill.l!L
`
`WIDE GATE OUT
`
`NARROW GATE OUT
`
`ADVANCE SIGNAL
`
`Fig. 4. TVI-100 circuit diagram.
`
`zontalline. The limitation is fixed by the bandwidth of
`the system which is just slightly greater than 4 MHz.
`It is possible to add data to more than one line at a
`time, making use of any line that has not been assigned
`or is not in use for test signals.
`
`ADDING DATA TO THE VERTICAL I TERVAL
`If we consider that we have access to one horizontal
`line (50 JJ-S) each 1/ 60 of a second in which to send in(cid:173)
`formation, this means we must wait approximately
`16 000 JJ-S before sending any other information. Storage
`is not necessary when adding test signals to the vertical
`interval since they are keyed directly into the selected
`line. However, to insert data, some means is needed to
`
`store the information generated at a fixed rate until it
`can be added to the video signal, such as the shift
`register in Fig. 2. Fig. 2 is a simple block diagra m of the
`vertical interval encoder or decoder system. It shows the
`TVI-100 Vertical Interval Encoder, a shift register,
`and the consumer's dig ital equipment. (The TVI-100
`can be either an encoder or a decoder, depending on the
`position of the encode/ decode switch shown in Fig. 3.)
`Starting with the video loopthrough (Fig. 4) we can
`follow the signal up to the noise filter, which is used to
`improve the signal-to-noise ratio of the system. The
`cutoff frequency is selected to roll off a peak white
`signal that precedes the front porch as much as possible
`without doing away with it altogether. The sync sepa-
`
`APPLE EX. 1020
`Page 4
`
`

`
`ANDERSON: THE VERTICAL INTERVAL
`
`79
`
`rator, a rather sophisticated device, is fed by a constant
`current source to prevent the average picture level from
`changing the clipping point.
`The stripped sync is then fed to a vertical integrater
`and to a low-pass filter, which improves the signal-to(cid:173)
`noise ratio even further. At this point, we actually
`invert the sync to trigger the monostable multivibrator.
`The output of this monostable is fed into a phase de(cid:173)
`tector that controls the frequency of a voltage-con(cid:173)
`trolled oscillator.
`In an earlier unit, the oscillator was shock-excited
`and the starting of the oscillator was determined by
`one horizontal sync pulse. If noise was present, a phase
`shift would result, which caused problems in getting the
`encoder and the decoder correctly phased together.
`In this later design, the voltage-controlled oscillator
`runs continuously. The horizontal sync pulses are inte(cid:173)
`grated for a complete frame, so if noise is present, it will
`average out and cancel. By feedback, we control the
`frequency and phase of the oscillator, causing it to run
`at about 7 MHz.
`The counter is TTL logic. You will notice it is marked
`for a count of 448. The monostables are a basic divide(cid:173)
`by-512 with the NAND gate detecting the 449th count
`and resetting the counter to zero. The counter is neces(cid:173)
`sary to lock the 7-MHz oscillator to the incoming sync
`for system timing.
`The TVI-100 provides for a wide and a narrow gate
`output. The narrow gate out is used for encoding, the
`wide gate out for decoding. These gate pulses are de(cid:173)
`rived from the counter: the divider is decoded to pro(cid:173)
`vide start and stop pulses to determine width of each of
`the pulses.
`Taps on the counter permit changing the clock fre(cid:173)
`quency, depending on the amount of data to be encoded
`in the vertical interval. Notice the lines from the gate
`circuit to the line counter. The line selector selects a
`line, 13 through 20. The monostables keep any incoming
`signal from triggering the line counter until the vertical
`interval approaches. When the vertical signal arrives,
`we start the line counter and let it run until it selects the
`desired line. To alert the character generator or com(cid:173)
`puter that information will be sent on the next line, an
`advance signal pulse is generated one line ahead of the
`line selected for transmission.
`The real key to the whole encoder is the analog gate
`circuit (Fig. 5). Starting from the video loopthrough,
`we see the input to the noise filter and sync separator.
`Notice the data input; we are in the encode mode. The
`data come into an emitter-follower that offers a high
`impedance to the video loopthrough and a low im(cid:173)
`pedance to the diode gate. When the narrow gate ar(cid:173)
`rives, we forward-bias the diode bridge, closing the gate.
`The TVI-100 clocks the data out of the shift register
`only when the diode gate is closed.
`The current adder, made of Ql and Q2, is designed
`so the collector junction is at ground potential. When
`
`t-NN--TO SYNC SEPARATOR
`
`Fig. 5. Analog gate circuit.
`
`the diode gate is closed, the digital information appear(cid:173)
`ing at the base of Q2 causes Q2 to require more current.
`This is supplied through the terminating resistor (R,)
`adding the digital information to the horizontal line
`that has been selected. The clamp is keyed from the
`counter circuit, so clamping is done on the back porch
`of the horizontal blanking.
`
`THE DECODING PROCESS
`If we put the encoder/decoder switch in the decode
`mode, the video signal now comes into the emitter(cid:173)
`follower. The gate circuit is controlled by the wide
`gate; data are encoded from the horizontal line in the
`vertical interval and coupled into the data output jack.
`The remaining circuitry is controlled to allow operation
`of this gate either to add data to the vertical interval
`or to remove them.
`What could happen to the video in the loopthrough
`path if the encoder malfunctions? You will notice that
`the system is capacitatively coupled. If C1 or C2 were
`to short, a high impedance remains parallel with the
`low impedance of the loopthrough.
`The current adder maintains a high impedance even
`when the diode bridge is forward-biased (gate closed).
`R,, the terminating resistor, is the load resistor and the
`current through it is determined by the unbalance in
`Ql and Q2 when the digital signal is coupled to the base
`of Q2.
`We should say more about how the digital informa(cid:173)
`tion is actually added to this horizontal line. The genera(cid:173)
`tor source resistance, shown in the figure, should be as
`close to 7 5 Q as possible to reduce reflection since the
`added signal energy tends to go both toward R. and R,.
`Tektronix has made us all aware of the importance of a
`return loss measurement; it is desirable that the return
`
`APPLE EX. 1020
`Page 5
`
`

`
`80
`
`IEEE TRANSACflONS ON BROADCASTING, SEPTEMBER 1971
`
`ADVANCE PULSE
`
`REMOTE CLOCK
`
`Fig. 6. Shift register to handle serial data.
`
`loss be better than 40 dB for optimum results.
`Return loss measurement, usually specified in deci(cid:173)
`bels, describes the amount of energy lost at the output
`of the loopthrough connector. Thus, if the video trans(cid:173)
`mission system is properly terminated, current adding
`in the vertical interval will be properly executed.
`
`REQUIRES SERIAL DATA
`
`Data can originate in various forms, but they must be
`in serial form in order to be encoded into the vertical
`interval. Since the data may be positive or negative
`logic, we can use the shift register as a buffer as well as
`a storage device. This also permits operation that is
`asynchronous with the TV system. In cases where we
`have large amounts of parallel data, the interface pack(cid:173)
`age is used to convert it to serial, then to binary phase
`modulation for best results.
`Fig. 6 shows a simple shift register used to handle
`serial data. Notice the block that represents the TVI-
`100. We see the video loopthrough and the symbol for
`current adder. The "Remote Clock" and "Data In"
`designations refer to slow data such as teletype, which
`are clocked in with its own timing device. The data are
`then shifted into the register. The wide gate serves as an
`inhib iting pulse to stop the incoming data while the
`TVI-100 clocks the data into the vertical interval.
`Usually a "#1" is sent to alert the decoder that data are
`coming.
`
`APPLICATIONS
`The versatility of the system is greatly expanded by
`its ability to selectively address a single station or a
`certain group of stations. It is important that the ad-
`
`(a)
`
`(b)
`
`(a) TVI-201 and (b) TVI-205 Vertical
`Fig. 7.
`Interval Control Encoder and Decoder.
`
`dress system be extremely reliable because of the one(cid:173)
`way nature of the transmission medium.
`TeleMation's TVI-201 Vertical Interval Control
`Encoder permits remote control of one or more video
`tape recorders. This unit, along with the TVI-205
`Vertical Interval Control Decoder (Fig. 7), can be used
`to operate any remotable device, selectively addressing
`and operating two latching relays and four momentary
`relays.
`Fig. 8 shows a typical remote addressing system. The
`two BCD switches on the TVI-201 permit the operator
`to formulate codes through 99. The two paired push
`buttons are latching relays; each of the other push
`buttons operate momentary relays. The TVI-205 De(cid:173)
`coder is programmed so that all units will respond to
`Code 99 for a common program and also respond to a
`
`APPLE EX. 1020
`Page 6
`
`

`
`ANDERSON: THE VERTICAL INTERVAL
`
`81
`
`PROGRAM VIDEO
`
`TRANSMITTER
`
`PROGRAM VIDEO WITH
`REMOTE VTR CONTROL COOES
`
`TVI-IOO +
`L--+---{~
`:
`TVI-201
`VERTICAL INTERVAL CONTROL
`ENCODER
`
`••
`
`••
`
`-
`
`-""!
`
`LOCATION
`I
`
`LOCATION
`3
`
`Fig. 8. Remote addressing system . The T\11-100 decodes the control codes from the progra m video a t receiver point. The
`T\11-205 transla tes the decoded control to activate the VTR.
`
`Fig. 9. Remote control data being sent on horizontal line.
`
`Fig. 10. Even on a noisy signal, data can be
`transmitted without error.
`
`program assigned to each one individually or a selected
`group.
`The use of the TVI-201 and TVI-205 will permit edu(cid:173)
`cational stations to selectively address tape recorders in
`their area. Station operators can turn on one or more
`preloaded tape machines, record the broadcast video
`signal, and shut off the recorders.
`Fig. 9, taken from the TVI-201, shows the complete
`horizontal line with the data being sent. The data con(cid:173)
`sist of address information and control functions with
`guard bits. To ensure against false operation, we send
`the command signal several times. As a further precau(cid:173)
`tio n against false operation, an integrator in the decoder
`requires that the correct address code (including correct
`guard bits) be received from approximately five con-
`
`secutive fields before the command is executed. The dura(cid:173)
`tion of the address code is t s or greater to provide in(cid:173)
`surance against failure to recognize a command.
`Fig. 10 shows a very noisy video signal with the da ta
`being received by the TVI-205. Even though the noise
`is at least as great in amplitude as the sync pulses, a ll
`digital functions are working very satisfactorily.
`Fig. 11 is a picture taken during an experiment in(cid:173)
`volving this system between Denver (KOA-TV) and
`Salt Lake City (KUED-TV). The TCG-1440 Char(cid:173)
`acter Generator, a long with associa ted transmitting
`equipment, was located in Denver. The TCG-1440 is
`USASCII Parallel. The interface package is the TDI-
`102, converting the parallel output of the character
`generator to serial and to binary phase-modulated
`
`APPLE EX. 1020
`Page 7
`
`

`
`82
`
`IEEE TRANSACTIONS ON BROADCASTING, SEPTEMBER 1971
`
`IN O~NVER AT THE 0Et4V
`EOUIPM£1fT USED
`CENTER
`IS AS FOI.,LQIIS:
`TKB-187 KEYBOARD
`INTERFACE
`TDI~l&Z DATA
`TDI-1113 DATA
`INTERFACE
`TDI-1&4 0AT4 INTERfACE
`SPOlllt.STER CARTR lOGE A!IIHO RECO~Df~
`TSG-tH& CHARACTER CENER'ATOR
`TV I• I GG ENCODER
`
`Fig. 11. Picture taken from TV receiver during VIDT test
`between Salt Lake City and Denver.
`
`signal. A page (560 characters) was transmitted in a
`little over 2 s.
`
`CoNCLUSION
`We feel this system has real potential as a means of
`disseminating information by a network to affiliated sta(cid:173)
`tions. By having such equipment at the point of origin
`and at each affiliate, it is easily possible to establish a
`reliable, continuous communications network at mini(cid:173)
`mal expense. Typically, the affiliate would be equipped
`with a ·separate control room monitor upon which pet(cid:173)
`work messages would appear. The network, by means of
`selective addressing, would address an individual.: ta(cid:173)
`tion, group of stations or all stations, transmitting pro(cid:173)
`gram
`log
`information, cueing
`information, rou ine
`messages or news flashes.
`
`At present, vertical interval data transmission is too
`new to permit accurate assessment of its potential. How(cid:173)
`ever, there is a broad variety of uses and the interest
`displayed by prospective users leads us to anticipate its
`finding wide acceptance in the television industry.
`Many of its proposed applications will require ·waivers
`or changes of FCC rules. It is hoped that the substan(cid:173)
`tially increased reliability of the new equipment avail(cid:173)
`able plus spectrum conservation afforded by use of the
`system will persuade the FCC to take a generous atti(cid:173)
`tude toward implementing the use of the vertical interval
`tra.nsmission and control apparatus. We are particularly
`in~ttrested in discovering new applications and we are
`anxious to discuss experimental projects that could lead
`to broadening the application and acceptance of this
`concept in the television industry.
`
`APPLE EX. 1020
`Page 8