EP0500704A1

EP0500704A1 - Signal processing apparatus for a widescreen television system

Info

Publication number: EP0500704A1
Application number: EP90917130A
Authority: EP
Inventors: Michael Anthony Isnardi; Jack Selig Fuhrer; Joshua Lawrence Koslov; James John Gibson
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1989-11-06
Filing date: 1990-11-05
Publication date: 1992-09-02
Also published as: PT95804A; JPH05501644A; WO1991007063A1; AU6748590A

Abstract

Dans un système de codage/décodage de signaux grand écran pour un signal de type télévision, les informations de chrominance (I, Q) du panneau latéral sont transmises (45, 46, 55) sous forme de double bande latérale sur un sous-porteur auxiliaire (SPA) ayant un phase d'inversion de champ par rapport à la phase d'un sous-porteur de chrominance normal. Les informations de luminance (YH) de haute fréquence du panneau latéral, à l'exclusion des informations de basse fréquence, sont également transmises (44, 50) sur le sous-porteur auxiliaire (SPA), mais sous forme de bande latérale individuelle. A titre d'exemple, le sous-porteur auxiliaire est à la fréquence de 3,58 MHz du sous-porteur de chrominance normal.In a wide screen signal coding / decoding system for a television type signal, the chrominance information (I, Q) of the side panel is transmitted (45, 46, 55) in the form of a double side band on a subcarrier auxiliary (SPA) having a field inversion phase with respect to the phase of a normal chrominance subcarrier. The high frequency luminance information (YH) from the side panel, excluding the low frequency information, is also transmitted (44, 50) to the auxiliary subcarrier (SPA), but as an individual sideband. By way of example, the auxiliary subcarrier is at the frequency of 3.58 MHz from the normal chrominance subcarrier.

Description

SIGNAL PROCESSING APPARATUS FOR A WIDESCREEN TELEVISION SYSTEM

This invention concerns apparatus for processing (encoding/decoding) a widescreen television-type signal having main and side panel information and an image aspect ratio, e.g., 16 x 9, greater than that of a standard television image.

A conventional television system, such as a system in accordance with the NTSC broadcast standard adopted in the United States and elsewhere, has a 4:3 aspect ratio (the ratio of the width to the height of a displayed image). Recently, there has been interest in using higher aspect ratios for television systems, such as 5:3, 16:9 and 2: 1 , since such higher aspect ratios more nearly approximate or equal the aspect ratio of the human eye than does the 4:3 aspect ratio of a standard television receiver display.

Advanced television systems for producing 5:3 aspect ratio images are described, for example, in U.S. patent 4,816,899 - Strolle, et al. and in U.S. patent 4,855,81 1 - Isnardi. In these systems side panel image information is encoded by time compressing low frequency side panel luminance and chrominance information into horizontal overscan regions, and by modulating time expanded high frequency side panel luminance and chrominance information on an auxiliary subcarrier. The side panel chrominance information in these systems encompasses a relatively narrow bandwidth of approximately 600 KHz.

It is also desirable for widescreen television systems to be compatible with standard television receivers to facilitate the widespread adoption of widescreen systems. One known compatible widescreen television system is described by M. A.

Isnardi et al. in an article "Encoding for Compatibility and Recoverability in the ACTV System", published in I E E Transactions on Broadcastin g. Vol. BC-33, December 1987, and in the aforementioned U.S. patent 4,855,81 1 of Isnardi. This known system includes apparatus designed for processing a widescreen video signal representing a 5 :3 aspect ratio image to develop a compatible widescreen television signal wh'ch produces a standard 4:3 aspect ratio display when received by a conventional television receiver, and which produces a widescreen 5:3 aspect ratio display when received by a widescreen television receiver. In this known system, low frequency side panel information is time compressed 6: 1 (resulting in a proportional increase in frequency) and placed in the horizontal overscan regions of the center panel information component. High frequency side panel information is time expanded about 1 :4.4 (resulting in a proportional decrease in frequency) before modulating a 3.1 MHz auxiliary subcarrier having a field alternating phase, forming a double sideband auxiliary signal which is combined with the main panel signal before being transmitted. To assist a decoder in recovering the center and side panel components at a widescreen receiver, the side panel and center panel luminance components are intraframe averaged above 700 KHz and 1.5 MHz respectively before modulation and combination at the transmitter.

If the described known compatible widescreen system were to process a 16x9 aspect ratio signal, images displayed by conventional NTSC receivers would exhibit noticeable geometric distortion, i.e., images would appear about 14% thinner. Geometric image distortion of about 5% or less is typically not noticeable by viewers. An attempt to meet this 5% distortion limit in the case of the known widescreen system resulted in having to reduce the side panel high frequency expansion factor, due to the side panel regions of a 16x9 display being wider than those of a 5x3 display. This produced an undesirable increase in the bandwidth of the time expanded side panel information. This matter, among others, is addressed by apparatus in accordance with the present invention.

In a widescreen signal processing system according to the present invention, side panel chrominance information is conveyed on an auxiliary subcarrier in double sideband form, and high frequency side panel luminance information is conveyed on an auxiliary subcarrier in single sideband form. In a preferred embodiment of the invention, an auxiliary subcarrier, at the frequency of a conventional chrominance subcarrier but exhibiting a field inverting phase relative to the phase of the chrominance subcarrier, is modulated both by the side panel chrominance information to produce a double sideband modulated signal, and by time expanded high frequency side panel luminance information exclusive of DC information to produce a single sideband modulated signal.

It is herein recognized as desirable, in accordance with an embodiment of the invention, to convey side panel chrominance information, such as the "I" color difference information, with a significantly greater bandwidth, than e.g. 600 KHz, in order to enhance side panel color resolution. In such a disclosed embodiment of the invention, first and second quadrature phased auxiliary subcarriers are modulated with first and second signals, respectively. The first signal contains both side panel high frequency luminance information and side panel narrowband "Q" color difference information. The second signal contains side panel wideband "I" color difference information. At a receiver/decoder, the auxiliary subcarriers are applied to a demodulator via a Nyquist filter for demodulating the side panel luminance and side panel "Q" color difference information, and to a demodulator for demodulating the side panel wideband "I" color difference information. The "I" modulating information as applied to both demodulators exhibits an inverse Nyquist characteristic which is the complement of that provided by the Nyquist filter. The inverse Nyquist characteristic is produced at a transmitter/encoder by an inverse Nyquist filter which filters the wideband "I" modulated auxiliary subcarrier. Brief Description of the Drawing

In the drawing:

FIGURE 1 illustrates a baseband frequency spectrum of a widescreen television signal developed in accordance with the principles of the present invention. FIGURES 2 and 3 illustrate optional frequency spectrums for side panel information in accordance with the present invention.

FIGURE 4 shows details of a 16x9 widescreen display associated with apparatus according to the invention. FIGURES 5 and 6 show baseband frequency spectrums of widescreen signal components according to the invention. FIGURES 7 and 8 respectively show compatible widescreen television signal encoder and decoder apparatus according to the invention.

FIGURES 9 and 10 respectively show widescreen television signal encoder and decoder systems including apparatus according to the present invention.

FIGURE 11 shows details of a 16:9 aspect ratio widescreen image display associated with apparatus according to the invention. FIGURE 12 illustrates a baseband amplitude-versus- frequency spectrum of a widescreen television signal developed in accordance with the present invention.

FIGURES 13-15 show additional baseband amplitude- versus-frequency spectra of signal components associated with the disclosed apparatus. The amplitudes of these spectra are not drawn to scale.

As shown by Figure 4, the width of an image display of a 16x9 aspect ratio widescreen display encompasses 754 image pixels, 542 of which constitute the center (main) panel display area and 1 16 of which constitute each of the left and right side panel areas as shown. The seams between the center panel area and the left and right side panel areas each include an overlap region containing about 5-10 pixels which may be processed in a variety of known ways to render the side-center seams virtually transparent to a viewer.

In the system to be described, television signals are sourced with a baseband bandwidth of 0-5.4 MHz, which is slightly greater than the 0-4.2 MHz baseband bandwidth of a standard NTSC video signal. The additional bandwidth assures that after time expansion and compression of the video signal as will be discussed, a resulting main signal component exhibits a 4:3 aspect ratio and a 0-4.2 MHz video bandwidth compatible with the signal processing requirements of a standard NTSC television system. The method of encoding side panel information in accordance with the principles of the present invention will be discussed before describing the overall operation of the system. Referring now to the frequency spectrum in Figure 1 , side panel luminance high frequency information ("side highs") exclusive of low frequency information including DC is time expanded and transmitted as a single sideband component of an auxiliary subcarrier signal (ASC) at a baseband frequency FASC of 3.58 MHz, which is also the frequency FSC of the standard chrominance subcarrier (actually 3.579545 MHz). The chrominance subcarrier is quadrature modulated with the center panel (main panel) I and Q components. Before time expansion, the luminance side highs signal has energy in the frequency range of 1.0 MHz to 5.4 MHz. After time expansion by a factor of 3.0, the side highs information is mapped to a lower frequency range of 0.33 MHz to 1.8 MHz, as shown in Figure 5. Side panel low frequency luminance information including DC is time compressed into horizontal overscan regions as described in U.S. Patent 4,816,899 - Strolle et al.

The 3.58 MHz auxiliary subcarrier has a phase which inverts from field to field relative to the phase of the standard chrominance subcarrier. The lower sideband of the modulated time expanded luminance side highs component ranges from 1 .78 MHz to 3.25 MHz. The upper sideband of the modulated time expanded luminance side highs component, which is removed by a 3.58 MHz lowpass filter, ranges from 3.91 MHz to 5.38 MHz (not shown). The side panels contain narrowband "I" and "Q" chrominance information with a bandwidth of 642 KHz (including DC), which is 1.284 times the 500 KHz bandwidth of standard NTSC narrowband chrominance components. The factor 1.284 is a center panel time expansion factor required to develop an NTSC compatible main component from the original widescreen signal .

After time expansion by a factor of 3.0, the side panel chrominance I and Q bandwidths drop from 642 KHz to about 210 KHz, as shown in Figures 5 and 6. This bandwidth is small enough to occupy the frequency gap between the upper limit of the lower sideband of the modulated luminance side highs information (3.25 MHz) and the upper frequency limit of the video spectrum (4.2 MHz), as shown in Figure 1. The time expanded side panel I and Q chrominance components quadrature modulate the same auxiliary subcarrier that is modulated with the time expanded side panel luminance high frequency information. In this example the side panel I component and the side panel luminance highs component are modulated by the same phase of the auxiliary subcarrier. Alternatively, the side panel Q component and the side panel luminance highs component could be modulated by the same phase of the auxiliary subcarrier. The side panel component of the frequency spectrum shown in Figure 1 advantageously exhibits negligible energy in the vicinity of the high frequency limit (4.2 MHz) of the video band due to a 0.41 MHz guardband between the upper limit of the sideband modulation spectrum (3.79 MHz) and the 4.2 MHz upper limit of the video band. Thus side panel information is largely insensitive to unwanted side effects of IF (Intermediate Frequency) signal processing, such as group delay. The guardband is determined in accordance with the expression

F - (FASC + SPBW/EXP), where

F is the upper frequency limit of the video base band (4.2 MHz), FASC is the frequency of the auxiliary subcarrier (3.58 MHz), SPBW is the side panel bandwidth before time expansion (0.642 MHz), and EXP is the side panel time expansion factor (3.0).

The choice of the 3.58 MHz chrominance subcarrier frequency as the auxiliary subcarrier frequency provides several other benefits. Hardware cost and complexity are reduced because this frequency is readily available at both the transmitter encoder and the receiver decoder. Quadrature crosstalk around

3.58 MHz creates similar chrominance artifacts in both center and side panels, thereby reducing dissimilarities in displayed side and center panel information. A so-called "jail bars" artifact is also significantly reduced or eliminated from an image displayed by a compatible receiver which receives the processed widescreen signal, since side panel chrominance information is placed horizontally adjacent to side panel luminance information in the frequency spectrum associated with the auxiliary subcarrier. The "jail bars" artifact is caused by modulation of high energy side panel chrominance information into portions of the horizontal- vertical-temporal spectrum that are demodulated as flickering luminance stripes in compatible NTSC receiver displays. In the disclosed system, interference caused by side panel chrominance information on standard NTSC receivers is advantageously controllable by means of the color saturation adjustment which is available to a viewer.

Some advanced television systems advantageously employ the signal processing technique of intraframe averaging for encoding side and center panel information to facilitate their subsequent separation at a receiver. One such system is disclosed in U.S. Patent 4,855,81 1 of M. A. Isnardi, for example. Intraframe averaging can begin at 1.5 MHz in the time expanded center panel region of the main signal to avoid impairing lower frequency vertical detail information, and encompasses the entire frequency range of side panel luminance highs and side panel chrominance signals. In the system to be described herein, intraframe averaging of side panel information advantageously begins at a higher frequency than in the previously mentioned known widescreen system described in U.S. Patent 4,856,81 1 , resulting in improved side panel motion rendition.

The system disclosed herein also exhibits less noise in the reconstructed side panel regions compared to the system described in U.S. patent 4,855,81 1. Most of the noise is associated with the side panel low frequency information, which had been time compressed by a factor of six prior to transmission. A reduced side panel low frequency time compression factor permitted by the present system beneficially reduces the amount of noise developed in reconstructed side panel low frequency information.

Figure 2 shows a side panel modulation frequency response associated with an optional choice of an auxiliary subcarrier frequency FASC at 3.9 MHz. With this modulation scheme, the lower limit of the modulated side panel information occurs at a higher frequency (2.1 MHz) than the modulation scheme of Figure 1 ( 1.78 MHz). This result advantageously permits intraframe averaging of main panel information, as will be seen in Figure 7, to begin at a higher frequency (approximately

2 MHz) for better main panel vertical-temporal response.

Figure 3 depicts a side panel modulation frequency response associated with another optional choice of an auxiliary subcarrier frequency FASC at 2.3 MHz. This scheme also advantageously allows intraframe averaging of main panel information to begin at a higher frequency (approximately 2 MHz) compared to Figure 1 , for better main panel vertical-temporal response. This modulation scheme causes modulated side panel chrominance information to produce a downward moving "checkerboard" pattern which may be less visible than the flickering color interference pattern produced under certain conditions by the scheme of Figure 1. However, such flickering color pattern is unlikely to be perceived by a viewer. Although the 4.1 MHz upper frequency limit of the scheme shown in Figure

3 approaches the 4.2 MHz upper frequency limit of the video band, very little energy is exhibited near the upper frequency limit of side panel high frequency luminance information. Thus it is expected that the effects of intermediate frequency signal processing and filtering will not adversely affect side panel high frequency luminance information to a significant extent. In addition, the low energy upper frequency region of side panel high frequency luminance information could be attenuated slightly, if necessary, without seriously degrading the quality of the side panel image.

Figure 7 shows details of widescreen television signal transmitter apparatus for encoding a compatible widescreen television signal in accordance with the present invention. In this example it is assumed that each of the left and right horizontal overscan regions is about 2 microseconds wide. A television signal source 10, such as a television camera, provides 525 line, 2: 1 interlaced chrominance components I' and Q' and a luminance component Y\ The I and Q chrominance components are respectively low pass filtered in the horizontal, vertical and temporal (HVT) dimensions by units 12 and 13 to produce filtered components IF and QF. Units 12 and 13 each include a 3x3 (pixel) diamond shaped low pass filter oriented along vertical-temporal (VT) diagonal axes, and a 600 KHz horizontal low pass filter. Luminance component Y' is filtered by an HVT chrominance notch (band reject) filter 14 to produce a filtered luminance component YF. Filter 14 includes an input 3x3 VT chrominance bandpass filter which receives signal Y', followed by a 2.0 MHz horizontal high pass filter. An output signal from the high pass filter is subtracted from input signal Y' to produce output signal YF.

Components IF, QF and YF are separately intraframe averaged by means of units 16, 17 and 18, respectively. As disclosed in U.S. patent 4,855,81 1 for example, intraframe averaging is a signal conditioning technique which prepares two spatially correlated signals for mutual combining so that they can be recovered efficiently and accurately afterwards, such as by means of a field storage device. More specifically, with this technique a group of pixels one field (262H) apart is made to contain pixels of identical value such as by replacing original pixel values with their average value. Signal YF is intraframe processed above a given frequency such as 1.5 MHz, while the full bandwidth of signals IF and QF is intraframe processed. Frequency selective intraframe processor 18 includes a bandsplitter which provides low band and high band (above 1.5 MHz) output components. The high band component is intraframe averaged and afterwards combined with the low band component to form the output signal of processor 18.

The center panel areas of intraframe averaged signals Y, I and Q are time expanded by a factor 1.284 in units 20, 21 and

22 respectively. The I and Q components from units 20 and 21 are applied to a chrominance modulator 24 where they respectively modulate 3.58 MHz quadrature phase related standard chrominance subcarriers SC and SC Subcarriers SC and SC are generated by a network including a 3.58 MHz sinusoidal signal generator 70 for developing carrier SC, and a 90° phase shifter 72 for developing quadrature carrier SC from carrier SC. An auxiliary subcarrier ASC is derived from carrier SC by means of a field phase control unit 74, which produces auxiliary carrier ASC with a phase that inverts from one field to the next relative to the phase of the standard chrominance subcarrier. A 90° phase shifter 76 produces an auxiliary subcarrier ASC in phase quadrature with auxiliary subcarrier ASC. Signal YF from filter 14 is also applied to a 1 MHz horizontal bandsplit filter 28 which divides signal YF into a low frequency component YL including DC, and a high frequency component YH above 1 MHz. The side panel region of signal YL is time compressed by a factor of 4.0 in a unit 30. The output signal from unit 30 contains side panel low frequency information time compressed into respective right and horizontal image overscan regions, each of which is assumed to be about 2 microseconds wide in this example. The time compressed luminance side lows signal from unit 30 and the time expanded center panel luminance signal from unit 22 are time multiplexed together by means of a time multiplexer (MUX) unit 32. An adder 38 combines the modulated center panel chrominance signal from unit 24, and the signal from MUX 32 containing main panel luminance information and low frequency side panel luminance information compressed into horizontal overscan regions, to produce an output signal designated as component I .

Component 1 contains information which is compatible with standard television receivers having a 4x3 image aspect ratio. This component is combined in a unit 40 with additional side panel information contained in a component 2 to produce a compatible widescreen television signal which will develop a 16x9 widescreen image when displayed by a widescreen receiver. The output signal from combiner 40 can be conveyed via any number of conventional transmission media such as terrestrial RF broadcast or cable, for example.

Side panel information component 2 is developed as follows. Luminance side highs signal YH from filter 28 is intraframe averaged by a unit 42 before being applied to a unit 44 which time expands the side panel portions of signal YH by a factor of 3.0. The side panel of chrominance components I and Q from units 16 and 17 are similarly processed by units 45 and 46, respectively. Thus the output signal from unit 44 contains time expanded high frequency side panel luminance information, and the output signals from units 45 and 46 respectively contain time expanded side panel I and Q chrominance information.

The luminance side highs output signal from unit 44 is applied to an auxiliary modulator 50 for modulating 3.58 MHz auxiliary subcarrier ASC having a field reversing phase relative to the phase of standard chrominance subcarrier SC. A resulting double sideband modulated output signal from modulator 50 is converted to a single sideband signal by removing the upper sideband via a 3.58 MHz horizontal low pass filter 52. Side panel chrominance components I and Q from units 45 and 46 modulate respective quadrature phase related 3.58 MHz field phase inverting auxiliary subcarriers ASC and ASC in an auxiliary quadrature modulator 55 to produce a double sideband chrominance side panels modulated auxiliary signal. In this example the side panel luminance highs component and the side panel chrominance I component modulate the same phase of the auxiliary carrier, ASC, via modulators 50 and 55 respectively.

The single sideband luminance side highs signal from filter 52 and the double sideband chrominance sides signal from modulator 55 are amplitude attenuated by factors of 0.5 and 0.25 in units 54 and 57 respectively, to reduce the likelihood of these signals creating interference in standard aspect ratio compatible receivers. The double sideband chrominance modulated signal from modulator 55 is attenuated more heavily than the single sideband modulated signal from modulator 50 because the chrominance modulated signal contains more energy due to its double sideband nature and due to the fact that it may contain a high energy DC component, e.g., in the case of a color video signal. The attenuated signals from units 54 and 57 are combined in an adder 60 to produce component 2, which is thereafter combined with component 1 in adder 40.

Figure 8 shows details of a portion of a widescreen television receiver including apparatus for decoding the widescreen signal generated by the arrangement of Figure 7. A received baseband encoded widescreen television signal (e.g., from an RF tuner and intermediate frequency assembly not shown) is applied to a 1.7 MHz horizontal bandsplit filter for producing an output low band signal (LOWS), and an output high band signal (HIGHS) which is applied to an intraframe processor 1 12. Processor 1 12 averages (additively combines) and differences (subtractively combines) image lines 262H apart within frames, above 1.7 MHz, to recover main component 1 at an averaging output AVG, and auxiliary component 2 at a differencing output DIFF, substantially free of vertical-temporal crosstalk. A 200 KHz horizontal crosstalk guardband is provided between the lower limit operating frequency of unit 1 12 and the 1.5 MHz lower limit operating frequency of the center panel intraframe averager in the encoder of Figure 7. Recovered component 1 from unit 1 12 contains information which is essentially identical to image information of main component 1 developed at the encoder due to high intraframe spatial correlation. Additional details of processor 1 12 can be found in previously mentioned U.S. patent 4,855,81 1.

The main component signal from the averaging output (AVG) of unit 1 12 is subjected to three dimensional horizontal, vertical and temporal filtering in a filter 1 14. Filter 1 14 includes 3x3 V-T and horizontal filtering networks for providing modulated main panel chrominance information at a bandpass (BP) output, and high frequency main panel luminance information devoid of chrominance information at a chrominance notch output (NOTCH). An adder 1 16 combines the low and high frequency main panel luminance components from the outputs of filters 110 and 1 14 to produce reconstituted main panel luminance information at an output. This information is combined with the overscan region luminance information (which includes the time compressed side panel low frequency information) by means of a time multiplexer 1 18.

The modulated main panel chrominance component from filter 1 14 is demodulated by means of a quadrature demodulator 120 responsive to quadrature phase related locally generated standard chrominance subcarrier reference signals SC and SC Demodulated output signals from unit 120 are horizontally low pass filtered by means of 0.5 MHz filters 122 and 124 respectively to produce narrowband chrominance components I and Q, which are respectively time compressed by main panel compression units 130 and 132 with the inverse of the corresponding main panel time expansion factor at the encoder so as to restore the original spatial dimensions of the main panel information. Similarly, the main panel and overscan components of the output signal from MUX 1 18 are respectively time compressed and time expanded by means of units 134 and 136 to restore their original spatial relationships.

Restored main panel chrominance component I from unit 130 and restored side panel chrominance component I from unit 162 are spliced by means of a splicer 140 to produce a reconstituted 525 line 2: 1 interlaced widescreen color component F. Restored main panel chrominance component Q from unit 132 and a restored side panel chrominance component Q from a unit 164 are spliced by means of a splicer 142 to produce a reconstituted widescreen color component Q' . Restored main panel luminance information from unit 134 and restored side panel luminance information are spliced by means of a unit 144 to produce reconstituted widescreen luminance component Y \ Reconstituted widescreen components I', Q' and Y' are afterwards matrixed and processed by conventional television video signal processing networks to produce color image representative signals suitable for display by an image reproducing device. The side panel components which are combined with the main panel components as noted above are developed from component 2 as follows.

Component 2 from the differencing (DIFF) output of processor 1 12 is amplified by a factor of 4.0 in a unit 150 to compensate for the attenuation by a factor of 0.25 in unit 57 of the encoder. The amplified signal is then demodulated by a quadrature demodulator 152 which responds to quadrature phase related auxiliary reference subcarrier signals ASC and ASC having the same characteristics as the corresponding signals employed by the auxiliary modulator network at the encoder. One demodulated output of unit 152 is filtered by a 2.0 MHz horizontal low pass filter 155 to produce side panel chrominance component

Q. The other demodulated output of unit 152 is filtered by a 2.0 MHz horizontal low pass filter 154 to produce a signal containing side panel high frequency luminance information and side panel chrominance component I. The side panel output signals from filters 154 and 155 are time compressed by units 156 and 157, which respectively exhibit the inverse of the encoder side panel time expansion factor. The output signal from unit 156 is processed by a 0.6 MHz horizontal bandsplit filter 162 to produce a side panel luminance high frequency component at a high pass output (H), and the side panel chrominance I component at a low pass output (L). An adder 170 combines the side panel luminance highs component with the side panel luminance lows component from unit 136 to produce the reconstituted side panel luminance component which is applied to splicer 144. The output signal from unit 157 is processed by a 0.6 MHz horizontal low pass filter 164 to produce side panel chrominance component Q which is applied to splicer 142 as mentioned previously. The process of time compression via unit 156 before bandsplitting in unit 162 advantageously develops wider frequency separation between the side panel I component and side panel high frequency luminance component YS H- This allows the design parameters of bandsplitter 162 to be relaxed. The design parameters of filter 164 also are permitted to be relaxed due to prior time compression by means of network 157.

Reference is made to FIGURES 4 and 1 1 before considering the details of the encoder and decoder apparatus shown in FIGURES 9 and 10. As previously discussed in regard to FIGURE 4, the width of an image display having a widescreen 16x9 aspect ratio illustratively encompasses 754 image pixels, 542 of which constitute the center (main) panel display area and 1 16 of which constitute each of the left and right side panel areas. In the frequency spectrum of FIGURE 1 1 , side panel high frequency luminance information YSH ("side highs"), exclusive of low frequency information including DC, is time expanded and modulates a nominal 90° phase of a 3.58 MHz auxiliary subcarrier (ASC). The frequency of the auxiliary subcarrier (FASC) is also the frequency FSC of the standard NTSC chrominance subcarrier (actually 3.579545 MHz). The standard NTSC chrominance subcarrier is quadrature modulated with the center panel (main panel) I and Q components. The phase of the auxiliary subcarrier reverses from field to field relative to the phase of the standard NTSC chrominance subcarrier.

The YSH modulating information is initially in symmetrical double sideband form with respect to the auxiliary subcarrier frequency, but the auxiliary subcarrier exhibits an unsymmetrical YSH vestigial sideband configuration after the YSH upper sideband is limited to the 4.2 MHz channel limit frequency. Luminance side highs signal YSH has energy in the frequency range of 1.0 MHz to 5.4 MHz before time expansion. After time expansion by a factor of 3.0, the side highs information is mapped to a lower frequency range of 0.33 MHz to 1.8 MHz. Side panel low frequency luminance information including DC is time compressed into horizontal overscan regions as described in U.S. Patent 4,816,899 - Strolle et al. In this regard it is noted that various disclosed frequencies and bandwidths are based upon a side panel low frequency luminance time compression factor of 4: 1 in this example. However, other time compression factors, such as 5: 1 , could also have been chosen depending upon the requirements of a particular system. The time expanded lower YSH sideband of modulated auxiliary subcarrier ASC ranges from

1.78 MHz to 3.25 MHz as shown in FIGURE 1 1. The time expanded upper YSH sideband of modulated auxiliary subcarrier ASC ranges from 3.91 MHz to 5.38 MHz but is limited to 4.2 MHz by low pass channel filtering, which produces unsymmetrical YSH sidebands. The side panels contain narrowband "Q" color difference information with a bandwidth of 642 KHz (including DC), which is 1.284 times the 500 KHz bandwidth of a standard NTSC Q color difference component. The factor 1.284 is a center panel time expansion factor for developing an NTSC compatible main component from the original widescreen signal. After time expansion by a factor of 3.0, the side panel chrominance Q bandwidth drops from 642 KHz to about 210 KHz. This bandwidth is small enough so that when double sideband modulated on a 3.58 MHz carrier it occupies the frequency gap between the upper frequency limit of the lower YSH sideband (3.25 MHz) and the lower frequency limit of the upper YSH sideband (3.91 MHz).

The side panels also contain wideband "I" color difference information to enhance side panel color resolution. The side panel wideband "I" information exhibits a bandwidth of approximately 1.5 MHz, which drops to 0.5 MHz after time expansion by a side panel time expansion factor of 3.0.

The time expanded side panel Q and wideband I chrominance components, hereafter referred to as QS and IS respectively, quadrature amplitude modulate the auxiliary subcarrier. Specifically, side panel narrowband chrominance component QS and side panel luminance highs component YSH are frequency division multiplexed and modulate the same quadrature (90°) phase auxiliary subcarrier component. This modulated auxiliary subcarrier component is designated ASC and exhibits unsymmetrical sidebands with respect to YSH information and symmetrical double sidebands with respect to QS information, as illustrated. Side panel wideband component IS modulates the 0° phase auxiliary subcarrier component. This auxiliary subcarrier component is designated ASC and exhibits double sideband IS modulation with an unsymmetrical amplitude characteristic around the 3.58 MHz auxiliary subcarrier frequency. The illustrated shape of the IS amplitude characteristic results from filtering IS modulated auxiliary subcarrier ASC with a 3.58 MHz high pass "inverse" Nyquist filter at a transmitter/encoder to facilitate proper quadrature demodulation without crosstalk at a receiver/decoder, as will be explained in connection with FIGURES 9 and 10.

The choice of the standard 3.58 MHz chrominance subcarrier frequency as the auxiliary subcarrier frequency provides several benefits. Hardware cost and complexity are reduced because this frequency is readily available at both the transmitter encoder and the receiver decoder. Phase errors around 3.58 MHz creates similar chrominance artifacts in both center and side panels, thereby reducing dissimilarities in displayed side and center panel information. Again the "jail bars" artifact, such as has been known to be present in some 5:3 widescreen systems, is also significantly reduced or eliminated from an image displayed by a compatible receiver which receives the processed widescreen signal, since side panel chrominance information is placed horizontally adjacent to side panel luminance information in the frequency spectrum associated with the auxiliary subcarrier.

FIGURE 9 shows details of widescreen television signal transmitter apparatus for encoding an NTSC compatible 16:9 aspect ratio widescreen television signal in accordance with the present invention. A widescreen television signal source 10, such as a television camera, provides 525 line, 2: 1 interlaced color difference components wideband I^* and Q' and a luminance component Y\ The wideband I' and Q' chrominance components are respectively low pass filtered in the horizontal, vertical and temporal (HVT) dimensions by units 212 and 213 to produce filtered components IF and QF. Units 212 and 213 each include a 3x3 (pixel) diamond shaped low pass filter oriented along vertical-temporal (VT) diagonal axes, and respective 1.5 MHz and 0.5 MHz horizontal low pass filter elements. Luminance component Y' is filtered by an HVT chrominance notch (band reject) filter 214 to produce a filtered luminance component YF. Filter 214 includes an input 3x3 VT chrominance bandpass filter which receives signal Y', followed by a 2.0 MHz horizontal high pass filter. An output signal from the high pass filter is subtracted from input signal Y' to produce output signal YF.

Components IF, QF and YF above 1.5 MHz are separately intraframe averaged by means of units 216, 217 and 218, respectively. As disclosed in U.S. patent 4,855,81 1 for example, intraframe averaging is a signal conditioning technique which prepares two signals for mutual combining so that they can be recovered efficiently and accurately afterwards, such as by means of a field storage device. More specifically, with this technique a group of pixels one field (262H) apart is made to contain pixels of identical value such as by replacing original pixel values with their average value. Signal YF is intraframe processed above a given frequency such as 1.5 MHz, while the full bandwidth of signals IF and QF is intraframe processed. Frequency selective intraframe processor 218 includes a bandsplitter which provides low band and high band (above 1 .5

MHz) output components. The high band component is intraframe averaged and afterwards combined with the low band component to form the output signal of processor 218.

The center panel areas of intraframe averaged signals Y, I and Q are time expanded by a factor 1.284 in units 220, 221 and 222 respectively. The I and Q components from units 220 and 221 are applied to a conventional NTSC chrominance modulator 224 where they respectively modulate 3.58 MHz quadrature phased standard chrominance subcarriers SC and SC Subcarriers SC and SC are generated by a network including a 3.58 MHz sinusoidal signal generator 270 for developing carrier SC, and a 90° phase shifter 272 for developing quadrature carrier SC from carrier SC. An auxiliary 3.58 MHz subcarrier ASC is derived from carrier SC by means of a field phase control unit 274, which produces auxiliary carrier ASC with a phase that reverses from field to field relative to the phase of the standard chrominance subcarrier. A 90° phase shifter 276 produces an auxiliary subcarrier ASC in phase quadrature with auxiliary subcarrier ASC. Auxiliary subcarrier ASC also exhibits a phase that reverses from field to field relative to the phase of the standard chrominance subcarrier.

Signal YF from filter 214 is also applied to a 1 MHz horizontal bandsplit filter 228 which divides signal YF into a low frequency component YL including DC, and a high frequency component YH above 1 MHz. The side panel region of signal YL is time compressed by a factor of 4.0 in a unit 230. The output signal from unit 230 contains side panel low frequency information time compressed into respective right and left horizontal image overscan regions, each of which is about 2 microseconds wide in this example. The time compressed luminance side lows signal from unit 230 and the time expanded center panel luminance signal from unit 222 are time multiplexed together by means of a time multiplexer (MUX) unit 232. An adder 238 combines the modulated center panel chrominance signal from unit 224, and the signal from MUX 232 containing main panel luminance information and low frequency side panel luminance information compressed into horizontal overscan regions, to produce an output signal designated as COMPONENT 1.

COMPONENT 1 contains information which is compatible with standard NTSC television receivers having a 4:3 image aspect ratio and which is intended to be viewed by a standard NTSC receiver. This component is combined in a unit 240 with additional side panel information contained in a COMPONENT 2 to produce an NTSC compatible widescreen television signal which will develop a 16:9 widescreen image when displayed by a widescreen receiver. The output signal from combiner 240 is frequency limited by means of a 4.2 MHz low pass filter 241. The filtered output signal can be conveyed via any number of conventional transmission media such as terrestrial RF broadcast or cable, for example. Side panel COMPONENT 2 is developed as follows.

Luminance highs signal YH from filter 228 is intraframe averaged by a unit 42 before being applied to a unit 244, which time expands the side panel portions of signal YH by a factor of 3.0 to produce signal YSH. The side panel portions of chrominance components wideband I and Q from units 216 and 217 are similarly processed by units 245 and 246 to produce time expanded side panel signals wideband IS and QS, respectively. Time expanded luminance side highs signal YSH is applied to an auxiliary 3.58 MHz quadrature amplitude modulator 250 for modulating 90° phase auxiliary subcarrier ASC. A resulting symmetrical double sideband YSH amplitude modulated output signal from modulator 250 is converted by means of output filter 241 to an unsymmetrical vestigial sideband signal with a 4.2 MHz upper frequency limit, as shown in FIGURE 1 1. Time expanded side panel chrominance component QS from unit 246 and time expanded wideband component IS from unit 245 are applied to an auxiliary 3.58 MHz quadrature amplitude modulator 255 including multipliers 280 and 282 and an adder 288. An inverse Nyquist slope filter 284 is associated with modulator 255. Signal QS modulates 90° phase auxiliary subcarrier component ASC via multiplier 280. Signal IS modulates 0° phase auxiliary subcarrier component ASC via multiplier 282. This modulated auxiliary subcarrier component is afterwards processed by inverse Nyquist slope filter 284 as will be discussed. Quadrature amplitude modulated auxiliary subcarrier components ASC and ASC are combined by adder 288.

The modulated luminance side highs signal from modulator 250 and the modulated chrominance sides signal from the output of combiner 288 in modulator 255 are amplitude attenuated by factors of 0.5 and 0.25 in units 254 and 257 respectively, to reduce the likelihood of these signals creating interference in standard 4:3 aspect ratio NTSC receivers. The chrominance modulated signal from modulator 255 is attenuated Page missing at the time of publication

image information of main COMPONENT 1 developed at the encoder due to intraframe processing. Additional details of processor 312 can be found in previously mentioned U.S. patent 4,855,81 1. The main COMPONENT 1 signal from the averaging output (AVG) of unit 312 is subjected to three dimensional horizontal, vertical and temporal filtering in a filter 314. Filter 314 includes 3x3 Vertical-Temporal and horizontal filtering networks for providing modulated main panel chrominance information at a bandpass (BP) output, and high frequency main panel luminance information devoid of chrominance information at a chrominance notch output (NOTCH). An adder 316 combines the low and high frequency main panel luminance components from the outputs of filters 310 and 314 to produce reconstituted main panel luminance information at an output. This information is combined with the overscan region luminance information (which includes the time compressed side panel low frequency information) by means of a time multiplexer 318.

The modulated main panel chrominance component from filter 314 is demodulated by means of a quadrature demodulator 320 responsive to locally generated, burst- referenced, standard NTSC chrominance subcarrier quadrature reference signals SC and SC. Demodulated output signals from unit 320 are horizontally low pass filtered by means of a 0.5 MHz filter 322 and a 1.5 MHz filter 324, respectively, to produce chrominance difference component Q and wideband chrominance difference component I. These components are respectively time compressed by main panel compression units 330 and 332 with the inverse of the corresponding main panel time expansion factor at the encoder to restore the original spatial dimensions of the main panel information. Similarly, the main panel and overscan luminance components are respectively time compressed and time expanded by means of units 334 and 336 to restore their original spatial relationships. Restored main panel chrominance component Q from unit 330 and restored side panel chrominance component QS from unit 362 are spliced by means of a splicer 340 to produce a reconstituted 525 line 2: 1 interlaced widescreen color component Q'. Restored main panel wideband chrominance component I from unit 332 and a restored side panel wideband chrominance component IS from a unit 364 are spliced by means of a splicer 342 to produce a reconstituted widescreen color component V. Restored main panel luminance information from unit 334 and restored side panel luminance information are spliced by means of a unit 344 to produce reconstituted widescreen luminance component Y\ Reconstituted widescreen components I', Q' and Y' are afterwards matrixed and processed by conventional television video signal processing networks to produce color image representative signals suitable for display by an image reproducing device. The side panel components which are combined with the main panel components as noted above are developed from COMPONENT 2 as follows. COMPONENT 2 from the differencing (DIFF) output of processor 312 is amplified by a factor of 4.0 in a unit 350 to compensate for the attenuation by a factor of 0.25 in unit 257 of the encoder (FIGURE 9). The amplified signal is demodulated by a 3.58 MHz synchronous quadrature amplitude demodulator 352 which includes multipliers 380 and 382. A Nyquist slope filter

384 is associated with demodulator 352. Demodulator 352 responds to quadrature phase related auxiliary reference subcarrier signals ASC and ASC synchronized with corresponding signals employed by the auxiliary modulator network at the encoder. Multiplier 380 responds to an auxiliary subcarrier reference signal ASC of nominal 90° phase, and to COMPONENT 2 from unit 350 after being processed by Nyquist slope filter 384, for producing demodulated side panel signals YSH and QS. Multiplier 382 produces side panel signal IS in response to COMPONENT 2 from unit 350 and in response to 0° auxiliary subcarrier reference signal ASC. FIGURE 14 illustrates the spectral diagram of YSH, QS modulated 90° phase auxiliary subcarrier component ASC after processing by Nyquist slope filter 384, before demodulation. FIGURE 15 depicts the spectral diagram of IS modulated 0° phase auxiliary component ASC after processing by Nyquist slope filter 384, before demodulation. The symmetrical double sidebands of the IS modulated quadrature component ASC shown in FIGURE 15 result from the cascade of decoder Nyquist slope filter 384 and complementary (inverse) encoder Nyquist slope filter 284.

The cascade of inverse Nyquist processing at the encoder with Nyquist processing at the decoder produces a desired flat amplitude response for demodulated signal YHS at the decoder, and also assures that modulated auxiliary subcarrier component ASC exhibits symmetrical double sideband IS information so that proper quadrature demodulation is achieved at the decoder, i.e., so that IS remains in desired phase relationship and does not crosstalk into components YSH or QS.

Imparting a Nyquist slope to the higher energy double sideband region of the combined YSH, QS modulated signal (from 3.08 MHz to 4.08 MHz) reduces the effective energy of the double sideband region by one-half, so that a flat demodulation amplitude response results over the auxiliary subcarrier modulation frequencies. Without Nyquist slope filtering at the decoder, demodulating auxiliary subcarrier component ASC would produce an uneven YSH output amplitude response due to the mutually unequal energy distribution in the unsymmetrical YS H sidebands. Nyquist slope filter 384 at the decoder symmetrically low pass filters quadrature modulated COMPONENT 2 such that a one-half amplitude response occurs in the middle of the higher energy double sideband region at the 3.58 MHz auxiliary subcarrier frequency, over the 3.08 MHz and 4.08 IS signal bandwidth, as shown in FIGURE 14.

COMPONENT 2 from unit 350 in the decoder (FIGURE 10) also contains quadrature modulation component IS, which is subjected to low-pass Nyquist slope processing by filter 384. Such processing causes IS modulated auxiliary subcarrier component ASC to have an uneven amplitude response over the range of IS modulation frequencies. To compensate for this amplitude effect, at the encoder the IS modulated auxiliary subcarrier component ASC is processed by high-pass Nyquist slope filter 284, which has the inverse (i.e., complementary) characteristics of decoder Nyquist slope filter 384. Thus, at the decoder, IS modulated auxiliary subcarrier component ASC, as applied to multiplier 380 in the YSH, QS demodulator, exhibits a symmetrical double sideband amplitude response over the range of IS frequencies as shown by FIGURE 15. This symmetrical double sideband response assures that the IS information will be in quadrature with the YSH, QS information at the demodulator, whereby the IS information is rejected by the YSH, QS demodulator. Inverse Nyquist slope filtering at the encoder also advantageously reduces the energy of signal IS, which reduces the likelihood that IS information will interfere with standard television signal information. The demodulated YSH and QS components are separated by subsequent filtering. The YSH, QS information is symmetrically double sideband over the 3.08 MHz - 4.08 MHz IS frequency range, and is rejected by IS synchronous amplitude demodulator 352. The demodulated IS output signal from unit 352 is filtered by a 2.0 MHz horizontal low pass filter 355. The YSH, QS demodulated output signal from multiplier 180 of demodulator 352 is filtered by a 2.0 MHz horizontal low pass filter. The side panel output signals from filters 354 and 355 are time compressed by units 356 and 357, which respectively exhibit the inverse of the encoder side panel time expansion factor. The output signal from unit 356 is processed by a 0.6 MHz horizontal bandsplit filter 362 to produce a side panel luminance high frequency YSH component at a high pass output (H), and the side panel chrominance QS component at a low pass output (L). An adder 370 combines the side panel luminance highs component with the side panel luminance lows component from unit 336 to produce the reconstituted side panel luminance component which is applied to splicer 344. The output signal from unit 357 is processed by a 1.5 MHz horizontal low pass filter 364 to produce side panel chrominance component IS, which is applied to splicer 342 as mentioned previously. Signals Y', I' and Q' are afterwards combined as known to produce a widescreen image representative signal for display.

Claims

CLAIMS:

1. In a system for processing a widescreen television- type signal containing main panel information and side panel information, apparatus comprising: means for processing said main panel information; means for (70,74) providing an auxiliary subcarrier signal other than a standard chrominance subcarrier signal; means for (45,46,55) modulating said auxiliary subcarrier with side panel chrominance information to form a double sideband modulated auxiliary subcarrier with respect to said side panel chrominance information; and means for (44,50) modulating said auxiliary subcarrier with side panel high frequency luminance information exclusive of DC information to form a single sideband modulated auxiliary subcarrier with respect to said side panel high frequency luminance information.

2. Apparatus according to Claim 1 , wherein said auxiliary subcarrier inverts phase every 262II where H is a horizontal line interval.

3. Apparatus according to Claim 1 , wherein said auxiliary subcarrier is at the frequency of said standard chrominance subcarrier and exhibits a field inverting phase relative to the phase of said standard chrominance su bcarrier.

4. Apparatus according to Claim 1 , wherein said side panel high frequency luminance information (YH) constitutes lower sideband information (52) of said single sideband signal.

5. Apparatus according to Claim 1 , wherein said widescreen television signal exhibits an image aspect ratio of approximately 16 X 9.

6. Apparatus according to Claim 1 , wherein said side panel high frequency luminance information (YH) constitutes upper sideband information of said single sideband signal; and said auxiliary subcarrier is at a frequency less than the frequency of said standard chrominance subcarrier.

7. Apparatus according to Claim 1 , wherein side panel low frequency information is time compressed (30) into an overscan region of said television signal.

8. Apparatus according to Claim 3, wherein said auxiliary subcarrier is at the frequency of said standard chrominance subcarrier.

9. Apparatus according to Claim 3, wherein said auxiliary subcarrier is at a frequency above the frequency of said standard chrominance subcarrier.

10. Apparatus according to Claim 1 , wherein said auxiliary subcarrier is at the frequency of said standard chrominance subcarrier and exhibits a field inverting phase relative to the phase of said standard chrominance subcarrier; said auxiliary subcarrier is quadrature modulated (55 ) with side panel chrominance information; and said side panel high frequency luminance information (YH) constitutes lower sideband information of said single sideband modulated auxiliary subcarrier.

1 1. Apparatus according to Claim 1 , wherein said modulated auxiliary subcarrier is combined (40) with processed main panel information in a common signal channel.

12. In a system for receiving a widescreen television- type signal containing main panel information, side panel chrominance information modulating an auxiliary subcarrier other than a standard chrominance subcarrier in double sideband form, and side panel high frequency luminance information exclusive of low frequency luminance information modulating said auxiliary subcarrier in single sideband form; apparatus comprising: means (1 12, 1 14) for separating said main panel information and said modulated side panel information demodulator (152) means responsive to a reference subcarrier for demodulating said side panel information; means ( 154-164) for processing demodulated side panel information; and means (140, 142) for combining processed demodulated side panel information with separated main panel information.

13. Apparatus according to Claim 12, wherein said auxiliary subcarrier and said reference subcarrier each exhibit a field inverting phase.

14. Apparatus according to Claim 12, wherein said auxiliary subcarrier is quadrature modulated with first and second side panel chrominance components; and said reference subcarrier comprises quadrature phase related components.

15. Apparatus according to Claim 14, wherein one of said first and second side panel chrominance components and said side panel high frequency luminance information are modulated in common with one of said quadrature phase related components of said reference subcarrier.

16. Apparatus according to Claim 12, wherein said separating means includes means ( 1 12) for summing and differencing picture elements separated by an image field for respectively producing separated main panel information and separated modulated main panel information.

17. Apparatus according to Claim 12, wherein said demodulating means (152) comprises quadrature demodulator means responsive to separated modulated side panel information and to an auxiliary reference signal for providing a first demodulated signal including a first side panel chrominance component (Q) at a first output, and a second demodulated signal including a second side panel chrominance component (I) and a side panel high frequency luminance component (YSH) at a second outpu t.

18. Apparatus according to Claim 17, wherein said auxiliary reference signal exhibits a field inverting phase relative to the phase of a standard chrominance subcarrier.

19. Apparatus according to Claim 17 and further comprising means (162, 164) for filtering output signals from said demodulating means for providing separate first and second side panel chrominance components and a separate side panel high frequency luminance component; and means (140-144) for combining said separate side panel luminance and chrominance components with main panel information to form a widescreen image.

20. Apparatus according to Claim 17 and further comprising means (156) for time compressing said second demodulated signal; and means (162) responsive to said time compressed second demodulated signal for separating said second side panel chrominance component and said side panel high frequency luminance component.

21. Apparatus according to Claim 17 and further comprising means (157) for time compressing said first demodulated signal; and means ( 164) for filtering said time compressed first demodulated signal.

22. Apparatus according to Claim 1 , wherein said side panel image information contains a luminance component and first and second color components, comprising: means (270-276) for providing first (ASC) and second (ASC) differently phased auxiliary subcarrier signals, other than a standard chrominance subcarrier conveying main panel chrominance information, at a common frequency; means (255,282,288) for modulating said first auxiliary subcarrier with said first side panel color component (IS) to form a double sideband modulated signal with respect to said first side panel color component; and means (250,255,260,280,288) for modulating said second auxiliary subcarrier with (a) said second side panel color component (QS) to form a double sideband modulated signal with respect to said second side panel color component, and with (b) side panel high frequency luminance information to form an unsymmetrical sideband modulated signal with respect to said side panel high frequency luminance information; wherein said first side panel color component (IS) is a wideband component having a wider bandwidth than said second side panel color component (QS).

23. Apparatus according to Claim 22, wherein said first and second side panel color components are "I" and "Q" color difference components, respectively.

24. Apparatus according to Claim 23, wherein said first (ASC) and second (ASC) auxiliary subcarriers are quadrature phase related and exhibit a field alternating phase unlike that of a standard chrominance subcarrier.

25. Apparatus according to Claim 22 and further including filter means (284) for imparting an unsymmetrical amplitude response over the modulation frequencies of said modulated first auxiliary subcarrier(ASC).

26. Apparatus according to Claim 25, wherein said filter means (284) is a Nyquist slope filter.

27. Apparatus according to Claim 22, wherein said filter means (284) is a high pass Nyquist slope filter; and said second auxiliary subcarrier (ASC) is a vestigial sideband modulated signal with respect to said side panel high frequency luminance information.

28. Apparatus according to Claim 22, wherein said modulated first (ASC) and second (ASC) auxiliary subcarriers are located in a common baseband channel.

29. Apparatus according to Claim 12 for receiving said widescreen television-type signal wherein side panel image information contains a luminance component and first and second color components, first and second differently phased auxiliary subcarrier signals other than a standard chrominance subcarrier sharing a common frequency, said first auxiliary subcarrier being modulated with said first side panel color component to form a double sideband modulated signal with respect to said first side panel color component, said second auxiliary subcarrier being modulated with (a) said second side panel color component to form a double sideband modulated signal with respect to said second side panel color component, and with (b) side panel high frequency luminance information to form an unsymmetrical sideband modulated signal with respect to said side panel high frequency luminance information, wherein said first side panel color component is a wideband component having a wider bandwidth than said second side panel color component; side panel signal processing apparatus comprising: means (312,314) for separating said main panel information and said modulated auxiliary subcarriers containing side panel information; first demodulator means (382) for receiving a first reference signal exhibiting the phase of said first auxiliary subcarrier, and for receiving a signal comprising said separated auxiliary subcarriers for providing a demodulated first side panel color component; and second demodulator means (380) for receiving a second reference signal exhibiting the phase of said second auxiliary subcarrier, and for receiving a signal comprising said separated auxiliary subcarriers, for providing a demodulated wideband second side panel color component.

30. Apparatus according to Claim 29 and further comprising

Nyquist slope filter means (384) for conveying said signal comprising said separated auxiliary subcarriers to said first demodulator.

31. Apparatus according to Claim 29, wherein said first and second side panel color components are respectively wideband "I" and "Q" color difference components;

.said first and second reference signals are quadrature phased and exhibit a field alternating phase unlike that of a standard chrominance subcarrier; and a Nyquist slope filter conveys said signal comprising said separated auxiliary subcarriers to said first demodulator.

32. Apparatus according to Claim 31 , wherein said Nyquist slope filter exhibits a low pass response.

33. Apparatus according to Claim 29, wherein said first and second auxiliary subcarriers are disposed in a common baseband channel.