US 2437300 A
Description (OCR text may contain errors)
March 9, 1948.
Filed Aug. 25, 1944 E. I ABINl TELEVISION AND SOUND TRANSMITTING SYSIM 2 Sheets-Sheet 1 Amm March 9, 1948. E. LABIN TELEVISION AND SOUND TRANSMITTING` SYSTEM Filed Aug. 2S, 1944 2 sheets-sheet 2 S Sw R Sw 19-44.41. 4j MN QN @E 2% NM EN.; n mH 4.4.4 eturlifdgfll@TLT- -@Titlwm ,-m4Lfv1mMfl l F r. b Naw/xm Y WE1 4 v @la mwlllt IIIIIIEIIIIIIIIIIIIEIIIIIIII SufC [wml f @lm l .l. .l .l ff Z. .0 N
INVENTOR Armi/VH Q www SA www@ Patented Mar. 9, 1948 TELEVISION vAND SOUND TRANSMITTING SYSTEM 'Emile Labin, New York, N. Y., Vassigner to. Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Delaware Application August 25, 1944, Serial No. 551,201
7 Claims. (Cl. P18-5.8)
This invention relates to television transmitting systems and more particularly to a system for transmitting a multiple of television programs.
Television broadcasting systems are being developed along substantially the same lines as the standard A. M. (amplitude modulation) broadcasting systems. The method used is the following: In the larger centers of population, New York city for examplethe studios of the several television broadcasting stations are situated conveniently to the program originating sources. From these studios the programs are piped by line to the respective transmitting stations which are located primarily for maximum populated area coverage and which transmit on individual authorized frequencies. At the receiving end the listener, of course, separates-the various stations by frequency tuning, l
While this system of broadcasting has proved entirely satisfactory for the lower frequencies, the same advantages do not necessarily follow at the higher frequencies employed in television. In fact, at these higher frequencies several major disadvantages arise. To give a few examples:
There can only be a limited number of optimum transmitting locations about the area to be served, and since height of the transmitting antenna in such area is all important at the higher frequencies, those stations not possessing these important locations are at a serious disadvantage with respect to their competitors. In New York city for example, there is only one Empire State *i building dominating in height the entire city and centrally located. The television broadcasting company controlling this location enjoys, therefore, a monopoly which even a considerably larger amount of power at other locati-ons cannot overcome.
The listeners receiver in an area served by several broadcasting stations is also at a distinct disadvantage with the existing system. With the various transmitting stations located at different compass points `with respect to the receiving location, it is not possible for a single simple receiving antennato be operated at maximum eiliciency due to the problem of reflections from' nearby buildings and other multi-path transmissions. This is especially tine with television, although not much less so with music and voice broadcasting. The practical reduction of these rellection effects entails lthe use of a' directive antenna which `when placed in the best position with respect to one transmitter might be quite unsatisfactory for receptions from another .transmitter. Hence, in order to receive all the stations, in addition to the normal receiving tuning, a delinitely impractical rotation of the antenna or a switching antenna system is necessary.
In addition to the above-mentioned disadvantages there are still others such as the duplication of transmitting apparatus and transmitting antenna towers, and the reduced eiiiciency of duplii cate operation.
It is an object of this invention to provide a multiple television broadcasting system which overcomes the above-,mentioned disadvantages of existing and other heretofore proposed broadcasting systems.
Another object is to provide a multiple television broadcasting system incorporating the unique advantage of ultra-high frequency .pulse transmission. Y f
Another object of the invention is to provide a multiple television transmitting system for transmitting all of the programs of a plurality of television transmitters over antennas located at a common advantage point for the area served.
A further object is to provide a method and means for television transmission whereby the synchronizing signals and the sound signals are transmitted on a multichannel carrier separate from the picturecarrier; and in the case of multiple television programs, each picture program is transmitted on a separate carrier frequency while the synchronizing signals and the sound signals for each picture program are transmitted over a single multi-channel carrier.
- Still another object of the invention is to provide a television transmitting system so arranged that the entire amplitude swing of the transmitter may be substantially fully employed for the picture signals alone.
The different carriers of the multiple television system are broadcast according to my invention over their respective antennas which I locate at a single vantage point such as at the top of the highest building of a city or on a tower located at some other high elevation within the area served. The antennas preferably are the omnidirectional type although they may have certain directional characteristics if desired. By this arrangement no one transmitter has the unfair advantage of having an antenna located much higher than another. By grouping the several transmitters the total transmitting equipment is simplied by combining certain operations. For
example, instead of transmitting the sound accompanying each picture over a separate sound transmitter at a frequency close to the picture carrier frequency, I concentrate al1 sound transmission in one single multi-channel transmitter. In addition, I utilize the same synchronizing signals for all of the picture transmitters and by transmitting the synchronizing signals separate from the picture signals, the entire amplitude swing of the picture transmitters can be fully employed for picture signals only. Further, the synchronizing signals being common to all picture transmitters serve to synchronize receivers for selective reception of any desired one of the picture programs as well as for the corresponding sound channel.
For a further understanding of thev invention, reference may be had to the following detailed description to be read in connection with the accompanying drawings, in which Fig. 1 is a block diagram of a multiple claims, such expression is to be regarded broadly tion.
For multi-channel transmission the pulses I3 are applied to a pulse multiplier 28 for producing a proper'nu'mber of pulses per second for the tele- Y vision transmitting system according to my invention, and
Fig. 2 is agraphioal illustration used in ex-v plaining the operating principles of the system.
In Fig. 1, an illustrated-example of a multiple television system is shown according to the principles of my invention. The system is shown for three television transmitters although a greater orlesser number may be provided as will be made clear from the following detailed description. Three sound transmitting channels i, 2 and 3 of a multi-channel transmitter liv are associated with the three picture transmitters 5, ii and l. The transmitters 4, 5, 6 and 'I operate on different carrier frequencies fn, f1, f2, and f3, as indicated, the outputs thereof being applied to antennas 9, IIl'and II, respectively, all of the antennas being mounted on a common tower I2 located at a Vantage point in the area served.
The same synchronizing signals are employed forthe different picture transmitters whereby the video signals of the diierent picture transmitters are all synchronized alike. The synchronizing pulses have-as their basis the pulses I3, graph a of Fig. 2, produced by base pulse producer` IA. The pulses I3 are preferably oi a repetition frequency desired for the horizontal synchronizing pulses although this is not essential. rIo obtain the horizontal synchronizing pulses I5, graph b, the pulses I3 are applied `to a horizontal synchronizing pulse Shaper I6. ri'he pulses I5 are shown to be of a given width whereby they are distinguished from other width pulses provided for other channels. To produce the vertical synchronizing pulses, the pulses i3 are applied to a pulse divider i'I whereby the pulse repetition frequency is reduced to the desired frequency for the vertical synchronizing pulses which correspond to the number of picture frames per second. The pulse divider Il may be arranged to shape the output pulse thereof for distinguishing the vertical synchronizing pulses from the horizontal synchronizing pulses but as shown I have included a separate shaper I3 for this purpose. The output pulses of shaper i3 are of a width indicated by vertical synchronizing pulse I 9 of graph c whereby it may be selected by pulse width discrimination from the other pulses of the multi-channel carrier.
While this system herein shown uses the s0- called horizontal and vertical synchronizing signals it will be recognized that other types of synchronizing signals may be used such as where a picture scanning method different from the line scanning method is employed. Therefore, where the expression synchronizing signals or synchronizing pulses are used in the appended different channels required. As shown by graph d, the multi-channel pulses 2l are four times the number of base pulses I3. This provides three channels for sound transmission and one channel for transmission of the horizontal and vertical synchronizing pulses. By increasing the number oi `multi-channel pulses 2I additional channels may be added. rl`his may be accomplished by maintaining narrow width pulses and decreasing the time intervals between pulses of successive channels.
According to the multi-channel feature ernployed vin this system the sound signals from sources 22, 23 and 24 are so chopped up relative to a base taken at a negative potential at or below the maximum negative signal value that interleaved segments of signal energy are obtained therefrom for modulation of the pulses 2l at time modulator 25 according to some principle of time modulation. In the example shown this is accomplished by applying pulses I3 to a Shaper 2S which widens the pulses to the width of the signal segment desired. These Wide keying or chopper pulses are applied for channel I through a delay device 21 whereby the chopper pulses for channel I are retarded an amount t1 causing them to coincide with the pulses of channel I as indicated in graphs d and e. The keyer pulses of shaper 26 thus retarded are applied to an amplier 23 to which the signal energy from source 22 is applied. The amplifier 28 is normally blocked to the signals from source 22 but is keyed to passthe signal energy in response to the keyer pulses. 'Ihe amplifier 28 thus selects pulse segments 29 of the signal energy for the duration of each keyer pulse. The pulse segments 29 of graph e for channel I are shown, for eX- ample, of a minimum value corresponding to a maximum negative value of signal energy. The pulse segments 33 for channel 2 are shown in graph f timed at interval t2 from pulses n and as decreasing in amplitude according to the signal energy indicated by envelope 3| from source 23. Likewise pulse segments 32 of graph g for channel 3 is timed an interval t3 from pulses r and are shown to represent progressively increasing values according to signal envelope 33 for source 24.
The interleaved pulse segments 23, 3l) and 32 are applied as a train of pulses to time modulator 25 to which the train of pulses 2| are also applied. Since pulse segments 29 coincide with the pulses of channel I, the pulses thereof are displaced in time position according to the respective vamplitude of the corresponding pulse segments 29. Any T. M. modulator may be used at 25 that is capable of displacing pulses according to the instantaneous Values of signal energy either by retardation or by a translation process. For retardation of pulses a delay network may be employed where the inductance includes one .t lne-lentes ltno .employment et e o odnlotol @dented toretortl hen '1s-esti* .Slneetlieinnlse seeniients nlltnderroln left to riehtloerenli fa sponeingreterda nl. h at the left and dec right yshell/.n:inle
ments? lnoreese lnemplitnele nl green oJ tlie .een sn in reases "from left olf'illiistretlonf llnefontpnt nlllses ottiniernoenletor@eine ope nliesl to miser t4 toeet o. r l and yvertical .pulses I 5l 1n telle lnlse retention -iri ein i otceeoeln einen t for .pones mixer is of known character having a limit clipping A leylel as indiategliath vwhereby the super-imposed pulses of graph h are eliminated leaving for transmission the pulse train indicated sin graplfi This pulse tlelnlntlnlles the tlorinontel synehronltlne nillses I5, the vertical synchronizingpnls I9 and the channel pulses I, 2 and 3. This train of multichannel pulses is applied from -fthemi-Xer 34 toA the transmitter 4 whereby the pulses aretransf mitted von acarrier frequency f *'.lne `ni'otnre Vioeo steriel horizontal lolenliille n11les M nien peles lett tile Sheller 8- vThese .sllnners may loe. of any1-known ny include for varying of the corresponding synchronizing pulse. This relationship is indicated in graphs i and y'.
The horizontal and. vertical synchronizing pulsesIS and I9 are applied together withthe blanking pulses vHB and VBto each of the Lpicture cameras 39, 40 and 4I to control alike the picture scanning of all the television cameras, the graph j serving as an example of the output of each television camera. It will be observed that since tno llorloontelleno yerftleelornonronltine `piilses .are otsnnerzlnnosedion. .tnelolonkine inlses of eo 'signet ,the -entire emnliterle 'swine of tllevtransniitters .5i-6 ene r1' .may :be employed ,-by the picture signals. In the systems lier.einlcnefore providing o r.tonl nosite video .steriel the pitture i' unnsllrnitedto n nertonlyof the enio. noityof ltlie transmitters so es toireserlre .et eert thereof .for-tile horizontal .end vertlenl Ysyl''1,olnronltine signals- ,Etten Atelevision reoetvler arranged to reeel-Ve simultaneously two fenrrriers, thelinnlti-onennel terrier onfreonenoy fo, and one of the other rier frequencies transmitted over .antennasi9l, Il!
and I.I The recoit/.er lstunable as tothe different rreqnenotes f1. fe., and is While reoeptionlofthe multi-enennel carrier foismelntainedfor the fre- @optioniof anyoneei tnefothers.. .In .this Way the :receiver ls'meintnlned ,in synonronlsmreeersle lessor the A.tuning from one to another of xcnetlinee orlnore ftelerisi'n snr-ogretnis- Tlfno tnnlneof tile reeeiner also ineliloleslneensifor tim-ine fiornone sonno Channel-.to enotner ln. aeoordenoewltntne nletllr-e Droereln rseleoteol lol' .lreonenoy timing:-
For e nioreieornplete oisonsslonfof tlle television receiver nrlnolnles reference met loe heil to my @il-ending application, Seriell No. 551,203, lell August, 2 5, r194e- -li-roln the-foregoing @le,serlntion.it is reollllrep- Perentthet @reinvention ororides-rnaxirnnrnuseage of the optimum transmitting location of each servite tirent lt `flxlso greatly .nllnlrnizes the troublesome reileotlon nrololeni :encountered :in
. television retention slnee eeen `neeelver be several tele lreetionel antenne installed 'flhis prot-isles for and leeliletl retention Qualit-i' Atromall-fef the tele- Visiontrensinitters,
eeldltlonto tile advantage of maximum and eoulnl retention quality, greater efficiency and lower oostfoperottion results .dueto the combining of the v7Common trens1nit-t.ine voperations of :tile
Y n:transmitting-systems. For eX- amnleftliere -isc'tlleielirninetion,of several duplicatiQIlS of .equipment in both the transmitter and antenna installations as is clear from lthe foregoing description. Y
yllhile inave described herein the vprinciples of my inyention infconnection with-a specific e1nbodiment, :it is to beclearly `understood that this description is madeonly by way of example and not asa limitation on theinilention and the scope ofthe. accompanying claims.
'1. A television --transmitting system comprising means vfor producing horizontal and vertical `syn-- chron'izing 4pulses for use with each of a plurality of television channels, means for producing lines of difieren-t picture signals for each channel in synchronlsm` with said Ahorizontal and Vertical synchronizing pulses, means to produce pulses modulated according to sound signals accompanying at least one of said picture signals, means to aiszeco transmit said picture signals on individual carrier frequencies, and means to transmit on another carrier frequency said horizontal synchronizing pulses, said vertical synchronizing pulsesand said sound modulated pulses.
2. A television transmitting system comprising means for producing a train of vertical synchronizing pulses of a desired repetition frequency, means for producing a train of horizontal synchronizing pulses at a repetition frequency equal to a given multiple of the repetition frequency of said vertical synchronizing pulses, means for producing lines of diiferent picture signals in synchronism with said horizontal and vertical synchronizing pulses means for producing a third train of pulses of the repetition rate of said horizontal pulses timed a given interval relative to said horizontal synchronizing pulses, means to time modulate said third train of pulses according to sound signals accompanying said picture signals, means to transmit said picture signals on individual carrier frequencies, and means to transmit on another carrier frequency said horizontal synchronizing, said vertical synchronizing and said time modulated pulses.
3. A multiple television transmitting system I comprising means for producing a train of horizontal and vertical synchronizing pulses, at least two separate picture line producing means each responsive to said train of synchronizing pulses for producing lines of picture signals for a television program, means for multi-channel modulating a train of pulses according to the sound accompanying each picture program, means for transmitting the picture signals of one of said line producing means on one carrier frequency, means for transmitting the picture signals of the second line producing means on a second carrier frequency, means to transmit on a third carrier frequency said horizontal and vertical synchronizing pulses and the train of sound modulating pulses.
4. A multiple .television transmitting system comprising means for producing a train of vertical synchronizing pulses of a desired repetition frequency, means for producing a train of horizontal synchronizing pulses at a repetition frequency equal to a given multiple of the repetition frequency of said vertical synchronizing pulses, at least two picture line producing means each responsive to said vertical and horizontal synchronizing pulses to produce lines of picture signals for a television program, means for producing a third train of pulses at the repetition rate of said horizontal synchronizing pulses, means to retard differently the vpulses of said third train to produce different series of pulses timed different intervals relative to said horizontal synchronizing pulses, means for modulating a characteristic of the pulses of the diiferent series according to the sound signals accompanying the different television programs, means for transmitting the picture signals of vone of said producing means on one carrier frequency, means for transmitting the picture signals of the second of said line producing means on a second carrier frequency, and means for transmitting said horizontal and vertical synchronizing pulses and each series of said sound modulated pulses on a third carrier frequency.
5. A multiple television transmitting system comprising a plurality of television transmitters 8 operating on different carrier frequencies, each transmitter having means for producing lines of picture signals separated by horizontal and vertical blanking intervals, means for producing a single train of horizontal and vertical synchronizing pulses for controlling the picture line producing operations of said transmitters, a multi-channel transmitter operating on still another carrier frequency having separate sound channels correspending-to the picture program of said television transmitters, and at least one further channel for transmission of said horizontal and vertical synchronizing pulses for synchronizing receivers for reception of any desired one of the programs transmitted from said television transmitters.
6. A method of transmitting a television program comprising producing horizontal and vertical synchronizing signals for use with each of a plurality of television channels, producing lines of different picture signals for each channel in accordance with the timing of said horizontal and vertical synchronizing signals, producing pulses a characteristic of which is modulated according to sound signals accompanying said picture signals, transmitting said picture signals on one carrier frequency, and transmitting on another carrier frequency said horizontal synchronizing signals said vertical synchronizing signals and said sound modulated pulses.
7. A method of transmitting a plurality of television programs comprising producing a train of horizontal and vertical' synchronizing pulses, producing lines of picture signals for each of the television programs in synchronism with said train of horizontal and vertical synchronizing pulses, producing a train of pulses, modulating a characteristic of different series of said train of pulses according to the sound accompanying the different television programs, transmitting the picture signals of said plurality of programs on diiferent carrier frequencies, and transmitting said train of horizontal and vertical synchronizing pulses together with the sound modulated pulses for said plurality of programs on still another Carrier frequency.
REFERENCES CITED The following references are of record in the ille of this patent:
UNITED STATES PATENTS Number Name Date 1,403,841 Carson Jan. 17, 1922 1,859,465 Piirington May 24, 1932 1,975,055 Weinberger et al. Sept. 25, 1934 2,089,639 Bedford Aug. 10, 1937 2,149,333 Brown Mar. 7, 1939 2,195,103v Urtel Mar. 26, 1940 2,227,045 Urtel Dec. 31, 1940 2,243,677 Lindenblade May 27, 1941 2,262,838 Delorain'e Nov. 18, 1941v 2,278,788v Knick Apr. 7, 1942 2,282,046 Goldsmith May 5, 1942 2,329,339 De Baun Sept. 14, 1943 2,414,453 De France J an. 21, 1947' FOREIGN PATENTS Number Country Date 322,025 Great Britain Nov. 28, 1929 450,303 Great Britain July 14, 1936