United States Patent [191 [11] Patent Number: 4,879,606 Walter‘ et a1. ' . [451 Date of Patent: Nov. 7, 1989

[54] EDTV RECORDING APPARATUS for IDTV/EDTV System,” IEEE Transactions Con [75] Inventors: James M. Walter, Columbus; sumer Electronics, vol. 34, No. 1, Feb. 88, pp. 228-235. - Krishnamurthy Jonnalagadda, Masami Itoga et al., “Two Channel FM Recording For Plainsboro; Robert E. Flory, High-De?nition Baseband Signals”, IEEE Trans. Con Princeton, of NJ. sumer Electronics, vol. 34, No. 1, Feb. 88, pp. 78-84. M. Isnardi et al., “Decoding Issues In The ACTV Sys [73] Assignee: General Electric Company, tem”, IEEE Transactions On Consumer Electronics, Princeton, NJ. vol. 34, No. 1, Feb. 1988, pp. 111-120. [21] Appl. No.: 205,146 Y. Yasumoto et al., “A Wide Aspect Ratio Television [22] Filed: Jun. 6, 1988 System With Full NTSC Compatibility”, IEEE Trans actions Consumer Electronics, vol. 34, No. 1, Feb. 88, [51] Int. (31.4 ...... H04N 9/79 pp. 121-127. [52] U.S. C1...... 358/330; 358/ 12; 358/16; 358/11 Primary Examiner-John W. Shcpperd [58] Field of Search ...... 358/12, 15, 16, 310, Attorney, Agent, or Firm—Joseph S. Tripoli; Eric P. 358/ 330, 11 Herrmann; James B. Hayes [56] References Cited U.S. PATENT DOCUMENTS [57] ABSTRACT 4,476,484 10/1984 Haskell ...... 358/ 16 - Extended de?nition television (EDTV) signals includ

4,485,401 11/1984 Tan et a1...... 358/12 ing a compatible composite wideband signal and a sepa 4,510,520 4/1985 Parker et a1. 358/15 rate helper or extended de?nition signal are combined, 4,521,803 6/1985 Gittinger 358/141 for example, for recording purposes, using frequency 4,535,352 8/1985 Haskell ...... 358/11 multiplexing techniques. The helper signal is applied to 4,543,598 9/1985 Oliphant ...... '. 358/12 a modulator, which produces a suppressed carrier mod 4,613,912 9/1986 Shibata et al. .. 360/191 4,654,724 3/1987' Nagano ...... 358/310 ulated signal, to frequency shift the helper signal to a 4,661,850 4/1987 Strolle et a1. 358/12 spectral band abovethe frequency band occupied by 4,661,863 4/1987 Ichinot ...... 358/334 the compatible composite wideband signal. The fre 4,694,338 9/1987 Tsinberg 358/141 quency shifted and wideband signal are then added to 4,742,386 5/1988 Wilkinson ...... 358/13 form the combined signal. OTHER PUBLICATIONS S. Higuchi et al., “An Experimental Color Under VCR 11 Claims, 3 Drawing Sheets

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10 5 ( 3+R ENCODEEDTV _> O 8 G CS2 H —> A C —I E B N —> R8 72 / MEM. —> WS RS WH “H H41‘ MEMORY CONTROL 4,879,606 1 2 equipment cost to the broadcasters but also creates EDTV RECORDING APPARATUS signi?cant synchronizing and timing problems to main tain the proper relationship between the two signals. This invention relates to extended de?nition televi The present invention obviates equipment duplicity sion (EDTV) systems. 5 and the timing and synchronization problems in an EDTV facility. BACKGROUND OF THE‘ INVENTION In, for example, the Isnardi et al. system higher fre EDTV systems are systems which are designed to quency video information is effectively folded into the transmit and receive television signals and provide the 4.2 MHZ spectrum bandwidth of composite video sig consumer with reproduced images of higher quality 10 nals. As such the wide bandwidth channels (15 MHZ) of than those available from e.g. conventional NTSC sys the studio equipment is under-utilized. In addition the tems. In addition it is highly desirable that the EDTV majority 'of studio equipment is transparent to the systems utilize conventional broadcast channels and be makeup of the signal being processed. compatible with existing television receivers, that is, Realizing these characteristics of the studio equip that existing receivers be capable of reproducing an ment, the present inventors discerned that the band EDTV signal with image quality substantially as good width of the limiting studio components (the 6 MHZ as conventional NTSC. bandwidth of VTR’s) is suf?cient to frequency multi Two such systems are described in the Feb. 1988 plex the lower bandwidth signal with the higher band volume of the IEEE Transactions on Consumer Electron width composite signal for transmission through the ics, (Vol. 34, No. l). The ?rst system is described in the 20 studio. article by Isnardi et al., entitled “Decoding Issues In The ACTV System”, at pages 111-120. The second SUMMARY OF THE INVENTION system is described in the article by Yasumoto et al., The present invention comprises a video signal pro entitled “A Wide Aspect Ration Television System cessing system including an encoder for generating a With Full NTSC Compatibility” at pages 121-127. 25 wideband video signal containing suf?cient information Both systms originate images in wide screen format, and for reproducing an image according to one of the con separately process the center and side portions of the ventional television standards, and for producing a fur image. Both systems generate a relatively wideband ther signal containing information, which when appro signal including information from the center image priately combined with the wideband signal, produces portions which is NTSC compatible. In addition both 30 an image of enhanced quality. Apparatus at the en systems generate a relatively narrowband signal con coder, frequency multiplexes the narrowband and wide taining auxiliary information for producing an enhanced band signals for local transmission among various pro image. The narrowband signal (V-T helper signal) gen cessing elements such as recording equipment. erated in the Isnardi et al. system includes ?eld differen tial signals for each image frame. This signal is utilized 35 BRIEF DESCRIPTION OF THE DRAWINGS in an EDTV receiver as an aid in generating progres FIG. 1 is a schematic drawing illustrating the fre sive scan signals with reduced motion artifacts. The quency spectrum of an EDTV signal, useful for describ narrowband signal- (multiplexed signal) generated in the ing the invention. Yasumato et al. system contains composite video infor FIG. 2 is a block diagram of an EDTV system em mation for the side portions of each image. bodying the present invention. Both the Isnardi et al. and Yasumato et al. system FIG. 3 is a pictorial representation of portions of transmit the wideband signal as a conventional NTSC several ?elds of video signal. signal. The narrowband signal is transmitted by quadra FIG. 4 is a block diagram of that portion of a particu ture modulating the picture carrier of the wideband lar EDTV system which generates a narrowband signal signal, so that all of the image information is transmitted 45 component. in a single channel. In contemporary broadcast studios for example, DETAILED DESCRIPTION video signals are generated in a camera and encoded The following description of the invention will be into NTSC format. Nominally these signals are cou expressed in terms of the Isnardi et al. EDTV system pled, over a single broadband conductor, to the various though it is to be understood that the invention is not studio processing, switching, special effects, etc. appa limited to the Isnardi et al. signal format. ratus, and then to the transmitter. To maintain signal Referring to FIG. 1, the spectral diagram A illus integrity much of the studio equipment has 15 MHZ or trates the spectral components of the wideband NTSC greater signal handling capability. Practically however, compatible signal produced by the Isnardi et al. EDTV the composite signal bandwidth is limited by the band 55 system (hereafter IEDTV). The signal consists of a width capability of video tape recorders, (VTR’s) luminance component S1 having frequency components which have a signal handling bandwidth of about 6 from zero to 4.2 MHZ, a frequency interleaved chromi~ MHZ. nance component S2 having frequency components The studio equipment does not have provision for from about 2MHz to 4.2 MHz, and a frequency inter handling the lower bandwidth signals generated in so leaved extended de?nition component S3 having fre EDTV systems. These signals must be carried around quency components from about 2-4.2 MHZ. The lumi the studio and delivered to the transmitter in parallel nance and chrominarice components contain informa with the wideband compatible NTSC signal. At the tion relating to the center portion of the image and also transmitter the two signals are combined for brbadcast includes compressed information relating to the side ing. In general it would appear that for a studio to han 65 panels. The luminance and chrominance signals are dle EDTV signals of the type having separate wideband combined in the conventional manner. Signal compo and narrowband components, duplicate equipment is nent S3 contains two subcomponents. The ?rst subcom required for the two signals. This not only doubles the ponent includes high frequency luminance information, 4,879,606 3 4 e.g., above 4.2 MHz. This information is frequency video recorder is approximately 6.1 MHz. The band shifted to the frequency band of 0-1.2 MHz. The second width of the IEDTV helper signal is 0.75 MHz. The subcomponent includes sidepanel high frequency infor carrier frequency for the modulated helper or extended mation which is encoded in NTSC format and fre de?nition signal of the IEDTV system, assuming dou quency shifted to the O —l.l MHz band. The two sub ble sideband modulation is thus 6.1 MHz minus 0.75 components are amplitude compressed and caused to MHz or approximately 5.35 MHz. This translates to quadrature modulate an alternate subcarrier of 3.1 approximately 682 fH/Z. Using 682 fH/Z there is substan MHz. The subcarrier is an interlaced frequency whose tially no mixing of the modulated extended de?nition phase is inverted on alternate ?elds. The quadrature signal and the wideband signal as indicated in the spec modulated alternate subcarrier is linearly added to com tral diagram C of FIG. 1. Note greater signal separation ponents S1 and S2 to form an NTSC compatible wide may be effected by utilizing a single sideband modu band composite video signal. lated signal rather than the double sideband signal as The spectral diagram B illustrates the frequency com illustrated. In this instance the carrier frequency applied ponents of the V-T helper or extended de?nition signal to the modulator 16 will be increased to about 6 MHz of the IEDTV system. This signal has a bandwidth (764 fH/Z). To produce a single sideband signal the out which is limited to 750 kHz. The generation of this put of modulator is coupled through a single sideband signal will be discussed hereinafter with reference to ?lter 17 (shown in phantom) having a passband cen FIG. 4. tered about the lower sideband of the signal generated In order to convey the wideband and extended de?ni by the modulator 16. tion signals on a single channel as discussed above, the 20 Depending on the particular EDTV encoder utilized, extended de?nition signal is frequency shifted by modu~ the wideband composite signal S W}; may not be band lating a further carrier and being added to the wideband width limited. For example the chrominance compo signal to form the frequency multiplexed signal shown nent may contain a wideband I color difference signal in the spectral diagram C of FIG. 1. component with frequency components extending to Referring to FIG. 2, a localized television signal man 25 5.1 MHz (3.58+l.5 MHz). In this instance the wide agement system is illustrated. This system may include band signal must be bandwidth limited to provide room for example an entire broadcast studio or simply be a in the spectrum for the modulated extended de?nition video tape recorder. In the former situation element 20 signal. This function may be provided by inserting a may include such items as a video switcher for selecting lowpass ?lter 15 with, for example, a 4.2 MHz cutoff various video signal sources, a video recorder, and between the wideband output terminal of encoder 12 special effects equipment to fade or freeze images, form and the summing circuit 18. image montages, alter the speed of image action, etc. In The combined signal Sm is coupled to the composite the latter situation element 20 may consist of a single signal input terminal of element 20 which may be con video recorder such as for example a type “C” VTR. sidered to be a video recorder having a 6.1 MHz signal High quality video signals are provided in primary 35 bandwidth. Element 20 produces a processed (e.g., time RGB component form by the image source 10. Image shifted) combined signal 8'," having the same format as source 10 may be a progressive scan video camera signa Sm. If the signal 8'," is to be transmitted in a stan which generates 1050_ lines of video signal per frame dard broadcast channel, it must ?rst be decomposed and interval. The RGB component signals are coupled to an reformatted because the bandwidth of signal S’m ex EDTV encoder 12 which produces a wideband NTSC ceeds the bandwidth of standard video signals. compatible signal, SW3, and an extended de?nition sig The signal 5'", from element 20 is coupled to a ?lter/ nal, SNB. demodulator, 22, which separates the wideband signal The extended de?nition signal SNB is coupled to a S’WB from the modulated narrowband signal and fre balanced modulator 16 which frequency shifts this sig quency shifts (by, e. g., synchronous demodulation) the nal to a spectral band above the spectral band occupied 45 narrowband signal S'NB down to baseband. The sepa by the wideband signal SW3. The modulated extended rated signals S’WB and S'NB are coupled to a modulator de?nition signal and the wideband signal are respec circuit 24 which quadrature modulates a picture carrier tively coupled to summing circuit 18 which develops with the two signals. The modulated picture carrier is the frequency multiplexed signal SM. The spectral con then applied to a broadcast antenna 26 or the RF input tent of signal SM for the IEDTV system comports with of an EDTV receiver 27. the spectral diagram C of FIG. 1. Generation of the V-T helper signal of the IEDTV Preferably the modulator 16 is of the type which system will be described with reference to FIGS. 3 and produces a suppressed carrier signal so no contribution 4. The dots in FIG. 3 represent lines of video signal is added to the wideband signal in the absence of the from portions of four ?elds of a progressively scanned extended de?nition signal. In addition it is preferred 55 image. Each of the columns of dots represents a portion that the frequency of the carrier be locked to an even of a ?eld/frame of video signal. In generating the wide multiple of one half the line frequency of the wideband band luminance signal component and the chrominance signal to minimize the potential for the generation of components, the progressive scan signals are converted beat frequencies between the combined wideband and to interlaced scanned signals by selecting alternate lines extended de?nition signals. In the FIG. 2 apparatus the of signal and discarding the intervening lines. The se carrier is developed by accessing the horizontal line rate lected lines of signal are shown circumscribed by square signal F H from the EDTV encoder 12 and applying it to boxes. The selected lines are time expanded from the the phase locked loop 14. Phase locked loop 14 gener progressive scan line interval of 31.78 usec to the inter ates a carrier signal of NfH/Z which is coupled to the lace scan line interval of 63.56 usec._ carrier signal input terminal of the modulator 16. 65 The V~T helper signal contains information resident The bandwidth limitation for element 20 is nominally in the discarded lines and is generated as follows. The determined by the bandwidth of the video recorder helper signal for each discarded line X is formed by included therein. The bandwidth of composite signal averaging the signals from the temporally adjacent lines 4,879,606 5 6 (e.g., (A+B/2) and subtracting the average from the elements. In this instance the extended de?nition signal signal representing line X, that is the signal V-T for line will include vertical information rather than vertical X is ‘equal to X-—-(A+B)/2. Since there is nominally a temporal information. The extended de?nition signal high degree of redundancy between temporally adja corresponding to line X will be generated according to cent lines the V-T helper signal will contain relatively the algorithm (X—(C+D)/2). For an extended de?ni little energy and have relatively low frequency compo tion signal of this type a compatible receiver will be nents. At the IEDTV receiver the interlaced signals are arranged to combine the average of vertically adjacent converted to progressive scan signals for display. The lines (C+D)/2 with the extended de?nition signal to originally discarded lines are reconstructed with the aid generate signals representing the discarded lines X. of the V-T helper signal. To reconstruct line X the The apparatus described above is intended to be ex receiver forms the average (A+B)/2 of lines A and B emplary. Armed with the foregoing information one from the wideband signal and adds this average to the skilled in the art of video signal processing systems will V-T helper (X—-(A+B)/ 2). The sum corresponds to be able to construct variations thereo without straying signal representing line X. from the spirit of the invention. For example the cir In FIG. 4 the progressive scan high quality RGB cuitry illustrated in FIG. 2 may be incorporated in a signals from image source 10 are applied to a matrix Camcorder. circuit, 50, which develops progressive scanned lumi What is claimed is: nance, Y, and two color difference signals I and Q. The 1. Apparatus for recording an extended de?nition luminance signal is coupled to the cascade connected video signal comprising: delay elements 56 and 58 each of which delays the lumi a source of video signal; nance signal by 525 progressive scan line intervals. an extended de?nition television signal encoder cou During alternate line intervals, luminance signal pro pled to said source and ‘responsive to said video vided by delay element 56 corresponds to selected lines signal for generating a wideband video signal rep for wideband signal generation. During the selected line resenting luminance and chrominance information; intervals, the signal is written into memory 70 at the 25 and generating a narrow band video signal repre progressive scan signal sample rate under the control of senting differences between horizontal video signal .the write address control signal W5. Thereafter the lines which are separated in one of a spatial and signal applied to memory 70 is read out at half rate to temporal dimension; expand each selected line signal to 63.56 usec. Memory modulator means for frequency shifting said narrow read out of the wideband luminance signal is controlled band signal to produce a modulated signal occupy by the read address signal RS. ing a frequency band above the frequency band During intervening line intervals signal correspond occupied by said wideband signal; ing to discarded lines is provided by delay element 56. combining means, coupled to said modulator means Concurrent with a discard line (X) being provided by and said encoder for combining said wideband delay element 56, temporally adjacent lines (A, B) are signal and the frequency shifted narrow band signal available at the output port of delay element 58 and the to produce a combined signal; and input port of delay element 56 respectively. The tempo means including composite video signal recording rally adjacent line signals (A, B) are coupled to adder 64 means coupled to said combining means for record which generates their sum and applies the sums to the ing said combined signal. divide-by-two circuit 62. The output signal from divide 40 2. The apparatus set forth in claim 1 wherein said by-two circuit 62, corresponding to the average of the modulator means comprises: temporally adjacent signals, is coupled to the subtracter means for providing a carrier signal; 60. The signal provided by delay element'56 is coupled suppressed carrier modulating means, responsive to to a second input port of the subtracter 60 which gener said narrow band signal, for modulating said car ates the time compressed V-T helper signal. During the 45 rier signal. 7 intervening line intervals the compressed V-T helper 3. The apparatus set forth in claim 2 wherein said (extended de?nition) signal is written to memory 72 at modulating means further includes ?lter means coupled the progressive scan sample rate responsive to the write to said suppressed carrier modulating means, for passing address signals W H. Thereafter the samples in memory a single side band of said modulated signal. 72 are read out at half rate responsive to the read ad 4. The apparatus set forth in claim 1 wherein said dress signal RH to expand the lines of extended de?ni wideband signal is formulated in horizontal line seg tion signal to encompass the interlace scan line interval. ments occurring at a line frequncy of fH, and said modu~ The I and Q component samples from the matrix 50 lator means comprises: are coupled to delay elements 52 and 54 to time align means for providing a carrier signal having a fre them with the luminance samples from delay element quency which is an integral multiple of said line 56. Selected lines of I and Q samples are written into frequency f;], and phase locked thereto; memories 66 and 68 respectively responsive to write modulating means, responsive to said narrow band address signals W5 and read out in time expanded for signal, for modulating said carrier signal. mat responsive to the read address signal R5. 5. The apparatus set forth in claim 1 wherein said The selected luminance Y, and I and Q lines of signal 60 means including composite video signal recording from memories 70, 66 and 68 are applied to the encoder means, further includes: circuitry 76, which generates the wideband signal de means coupled to said composite video signal record picted in the spectral diagram A of FIG. 2. ing means for separating said combined signal into The write address signals W5 and WH and read ad a ?rst signal representing said wideband video dress signals R5, R11 are generated in a conventional signal and a second signal representing said narrow . manner by the memory control circuit 74. ' band signal; and In an alternative embodiment delay elements 52, 54, further modulator means for modulating an RF pic 56 and 58 may be realized with one-line-period delay ture carrier with said ?rst and second signals. 4,879,606 7 - 8 6. A video signal processing system comprising: 9. The video signal processing system set forth in a source of video signal formatted in ?eld/frames of claim 8 wherein said means for frequency shifting said horizontal lines of image information; further luminance signal comprises: means for generating a carrier signal; encoder means coupled to said source and responsive 5 a balanced modulator, responsive to said carrier sig to said video signal for generating a wideband and nal and said further signal for generating a modu a further luminance signal, said wideband lumi lated double sideband suppressed carrier signal; nance signal being a baseband signal compatible and with conventional broadcast standards, said further ?lter means coupled to said balanced modulator for luminance signal representing signal differences passing a single sideband of said modulated double between one of spatially and temporally adjacent sideband suppressed carrier signal. horizontal lines of video signal occuping a fre 10. The video signal processing system set forth in quency spectrum adjacent the frequency spectrum claim 8 wherein said means including recording means further includes lowpass ?lter means for coupling said of the wideband luminance spectrum; and wideband luminance signal to said signal summing means including recording means for recording said means. ” wideband and further luminance signals. 11. A video signal processing system comprising: 7. The video signal processing system set forth in a source of extended de?nition television signals in claim 6 wherein said means including ‘recording means cluding a wideband composite video signal format comprises: ' 20 ted in frame/?elds of horizontal image lines, and a combining means for separably combining said wide difference signal representing differences between band and further luminance signal into a combined signals from one of temporally and spatially adja signal; and cent image lines; a source of a carrier signal synchronized to the rate of a video signal recorder for recording said combined 25 occurrence of said horizontal image lines; signal. , suppressed carrier modulator means, responsive to 8. The video signal processing system set forth in said difference signal, for modulating said carrier to claim 7 wherein said combining means comprises: produce a frequency shifted difference signal oc means, responsive to said further luminance signal, cuping a frequency spectrum adjacent the fre for frequency shifting said further luminance signal quency spectrum of the composite signal; to a spectral band substantially exclusive of the signal summing means coupled to said modulator and said source of extended de?nition television signal band of frequencies occupied by said wideband for combining said wideband composite signal and luminance signal; and said frequency shifted difference signal to produce signal summing means for linearly combining said a combined signal; and wideband luminance signal and frequency shifted means for recording said combined signal. further luminance signal. * * * * *

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