CN1128538C - NTSC video signal receivers with reduced sensitivity to interference from Co-channel digital television signals - Google Patents

Abstract

A video signal receiver for reducing interference sensitivity of co-channel digital TV signals includes a circuit for selecting a vestigial sideband amplitude modulation signal, converting the signal into an intermediate frequency signal and amplifying it. The vestigial sideband AM signal is selected from a channel containing interference. The amplified IF signal is co-detected to generate an in-phase co-detection response and a quadrature-phase co-detection response. The frequency components of the quadrature-phase coherent detection response above the predetermined frequency are phase shifted by 90° and combined with the in-phase coherent detection response to recover the low frequency portion of the video signal, which is almost free of interfering products. The low-frequency and high-frequency portions of the video signal are combined to obtain a full-band video signal.

Description

NTSC Video Signal Receiver with Reduced Sensitivity to Co-Channel Signal Interference

This is a continuation-in-part of Patent Application No. 08/821,944, filed March 21,1997.

technical field

This invention relates to NTSC television signal receivers, and more particularly to improvements in such receivers for rendering them substantially less sensitive to interference from co-channel digital television signals.

Background technique

A receiver for the video portion of an analog television signal is described in U.S. Patent No. 5,122,879, filed June 16, 1992, by Katsu Ito, entitled "Television Synchronization Receiver with Reduced Interference from a Lower Adjacent Channel Using a Phase Shifter" , which synchronously detects received analog television signals in both in-phase and quadrature phases. By avoiding the use of amplifiers with varactor tuning to improve noise figure, the Ito receiver synchronously converts the RF (radio frequency) amplifier response directly to baseband so that an adjacent lower channel can appear as one image. All video above 750 KHz of the quadrature-phase coherent response is phase shifted by 90° and linearly combined with the in-phase coherent response to suppress image frequency components that transition to baseband during synchronous detection of the video portion of the received NTSC signal. In US Patent No. 5,122,879, Ito does not disclose that this process also removes video components above 750KHz. In small display TV receivers, this concomitant loss of brightness at high frequencies is acceptable, however, this is only the case for watches.

Contents of the invention

It is shown here that by modifying the band-limited video signal receiver described by Ito to phase-shift the quadrature-phase synchronous detection response by 90° at all video frequencies, the interference of co-channel interfering digital television signals is eliminated from the band-limited baseband NTSC signal product. Assuming that the time constant of the automatic gain control circuit in the receiver is several horizontal scan lines, only a 90° phase shift of the quadrature phase synchronous detection response for frequencies above a few kilohertz can prevent co-channel interference in band-limited video signals The artifacts of the digital television signal appear on the television display or interfere with horizontal synchronization.

The present invention provides a video signal receiver with reduced sensitivity to interference from co-channel digital television signals, said video signal receiver comprising: a first input circuit for selecting a vestigial sideband amplitude modulation describing the video signal signal, converting said selected vestigial sideband AM signal into a first intermediate frequency signal and amplifying said first intermediate frequency signal to provide an amplified first intermediate frequency signal, initially received by said first input circuit The vestigial sideband AM signal includes a video carrier and full sidebands in addition to a vestigial sideband, and the vestigial sideband AM signal is selected from a plurality of channels, one or more of which often contains signals from a The same channel interference of digital television signal; it is characterized in that, described video signal receiver also comprises: Video synchronization circuit, for according to described video carrier signal and according to a carrier wave that differs with described video carrier signal on phase by 90° to synchronously detect the amplified first intermediate frequency signal for generating a first in-phase synchronous detection response and for generating a first quadrature phase synchronous detection response; All frequency components of the first quadrature-phase synchronous detection response above the frequency are shifted by 90° to produce a first phase-shifting circuit response; a first linear synthesis circuit takes the first in-phase synchronous detection response combined linearly with said first phase shifting circuit response to recover the lower frequency portion of said video signal depicted on said full sideband and on said vestigial sideband, free of any co-channel interference a digital television signal; and circuitry for recovering a higher frequency portion of said video signal depicted on said full sideband but not on said vestigial sideband.

The term "linear combiner" as used in this specification and its appended claims is a generic term for "additive combiner" or "adder" and "differential combiner" or "subtractor".

According to another aspect of the invention, the video signal receiver further includes circuitry for recovering the higher frequency portion of the video signal described on the full sideband of the vestigial sideband AM signal rather than on its vestigial sideband. The vestigial sideband AM signal supplied to such circuitry for recovering the higher frequency portion of the video signal is selectively filtered to remove any pilot carrier signal components of the co-channel digital television signal. Doing so avoids any artifacts of this pilot carrier signal that would be produced when recovering the higher frequency portion of the video signal. The video receiver also includes circuitry for linearly combining the higher frequency portion of the video signal on both the full sideband and the vestigial sideband AM signal with a lower frequency portion of the video signal As described, and almost free of any co-channel interfering digital TV signal products.

Description of drawings

Figures 1, 2, 3, 4, 5, 6 and 7 are each a block diagram of a television receiver capable of receiving NTSC analog TV signals as well as DTV signals respectively, the television receiver employing the method of the present invention to detect signals in interfering NTSC analog The appearance of the DTV signal on the same channel as the TV signal.

FIG. 8 is a preferred spectral response curve for portions of the television receivers of FIGS. 1, 2, 3, 4 and 5. FIG.

FIG. 9 is a block diagram of a synchronization circuit usable in any of the television receivers of FIGS. 1, 2, 3, 4, 5, 6 and 7. FIG.

FIG. 10 is a preferred spectral response curve of a portion of the television receiver of FIGS. 6 and 7. FIG.

Detailed ways

Figure 1 shows a television receiver capable of receiving NTSC analog TV signals as well as DTV signals. The over-the-air TV signal received by the antenna 1 is amplified by the tunable radio frequency amplifier 2 and sent to the first detector 3 . The radio frequency amplifier 2 and the first detector 3 have a tunable function and together they form the function of a tuner to select said digital television signal from channels at different positions in a frequency band. The first detector 3 comprises a first local oscillator providing a first local oscillator tunable in a frequency range above the Ultra High Frequency (UHF) TV broadcast band, and a first mixer, the first The mixer mixes this first local oscillator with the TV signal selected by the tunable radio frequency amplifier 2 to up-convert the selected TV signal to produce a 6-MHZ-bandwidth UHF at the frequency of the above-mentioned channel in the UHF TV broadcast band UHF intermediate frequency signal in the intermediate frequency band.

The first detector 3 supplies the IF band signal to the UHF band IF amplifier 4 for the NTSC audio signal, the UHF band IF amplifier 5 for the full-band NTSC video low signal, and the UHF band IF amplifier for the NTSC video high signal 6. The responses of the UHF band IF amplifiers 4, 5 and 6 are provided to respective second detectors 7, 8 and 9 for downconversion to respective VHF band IF signals in the VHF band below the very high frequency of the channel. The second detectors 7, 8 and 9 share a common second local oscillator for generating the second local oscillator and have their own second mixers to combine these second local oscillators with the UHF band intermediate frequency amplifier 4 respectively. , 5 and 6 responses are mixed together. The VHF band IF signals from the second detectors 7, 8 and 9 are respectively supplied to VHF band IF amplifier 10 for NTSC audio signal, VHF band IF amplifier 11 for full band NTSC video low signal and for NTSC video high signal VHF band intermediate frequency amplifier 12.

UHF band amplifiers 4, 5 and 6 include surface acoustic wave (SAW) filters for UHF mid-band NTSC audio signals, UHF mid-band full-band NTSC video signals and UHF mid-band NTSC video high signals, respectively. A passband SAW filter with a steep notch edge but a linear group delay and flat amplitude response is easier to do in UHF than VHF. This is why it is best to determine the total IF response for a UHF IF-band NTSC audio signal, a UHF IF-band full-band NTSC video low signal, and a UHF IF-band NTSC video high signal in the UHF IF-band rather than in the VHF IF-band.

The pair of SAW filters in the IF amplifier 5 for determining the overall IF response of the full-band NTSC video low signal ranges from 500 KHz to at least above the lower limit of a 6 MHz wide TV broadcast channel as a conversion of the VSB AM signal to the UHF IF band Those portions of the VSB AM signal between 3.5 MHz preferably have a substantially flat response, rejecting in-channel and adjacent channel NTSC audio signals, and have a substantially linear phase response throughout its passband. As long as the linear phase response is maintained from the NTSC video carrier frequency to 750KHz, the SAW filter in the IF amplifier 5 can reject or reject any co-channel interfering pilot carrier of the ATSC DTV signal. The self-resonance of the IF filter for low full-band NTSC video signals excited by impulse noise is near the middle of the IF passband. Therefore, if the IF filtering has at least a 3MHz bandwidth, ringing caused by impulse noise is less likely to affect the baseband video response below 750KHz.

The SAW filter in the IF amplifier 6 for determining the overall IF response of the NTSC video high signal rejects the in-channel and adjacent channel NTSC audio signals, and preferably this SAW filter pair acts as a switch to the UHF IF band The lower limit of a 6MHz wide TV broadcast signal around 1.75MHz exhibits a roll-off and an essentially linear phase response throughout the passband. A roll-off of around 1.75MHz for a 6MHz wide TV broadcast channel as a transition to IF does not receive adjacent channel NTSC audio signals, any co-channel interfering pilot carrier of ATSC DTV signals, and in-channel NTSC video carriers. The SAW filter in the IF amplifier 6 preferably exhibits a roll-off around the upper limit 550KHz of the 6MHz wide TV broadcast channel as converted into the UHF IF band and discards the in-channel audio signal.

FIG. 8 shows the desired overall response of the receiver at the outputs of the UHF intermediate frequency amplifiers 5 and 6 with reference to the lower frequencies of the original transmission channel.

The UHF band IF amplifiers 4, 5 and 6 may comprise broadband fixed gain amplifiers for driving their partial SAW filters from source impedance to minimize multiple reflections and for overcoming insertion loss of their partial SAW filters. The VHF band intermediate frequency amplifiers 10, 11 and 12 each include a controlled gain amplifier providing an amplification factor of up to 60 dB or more. Each VHF band intermediate frequency amplifier 10, 11 and 12 includes a forward automatic gain amplification control section responsive to the output signal level of the intermediate frequency amplifier 11. The forward AGC is preferably used to tolerate better noise figure. The radio frequency amplifier 2 is provided with an inverse automatic gain control responsive to the delay of the output signal level of the intermediate frequency amplifier 11.

The response of VHF IF amplifier 10 is provided to intercarrier audio detector 13, which provides the 4.5 MHz intercarrier audio IF signal to intercarrier audio IF amplifier 14, which amplifies and symmetrically limits the supply to FM in most designs. The amplified response of the detector 15. The FM detector 15 reproduces the baseband composite audio signal supplied to the sound reproduction section 16 of the NTSC receiver every normal operation. The audio reproduction section 16 of an NTSC receiver typically includes stereo decoding electronics. If the NTSC audio signal is selected in the IF amplifiers 4 and 10 as a narrow-band filter that can only pass through the FM audio carrier as a conversion to IF, then the intercarrier sound detector 13 can provide a multiplier that combines the response of the IF amplifier 10 with the The video carrier provided by the third local oscillator in circuit 17 to synchronize the full-band NTSC video low signal to baseband is multiplied.

In addition, if the NTSC audio signal is selected as a filter for conversion to IF in the IF amplifiers 4 and 10 to pass both the NTSC video and audio carriers, in order to achieve "quasi-parallel" audio, the intercarrier audio detector 13 can Is a simple rectifier or a square law device. The third local oscillator in circuit 17, which is used to synchronize the full-band NTSC video signal to baseband, then no longer provides the video carrier.

The output signal from the VHF intermediate frequency amplifier 11 is supplied to a circuit 17 for synchronously converting NTSC video carrier modulation to baseband, which circuit may take the structure shown in FIG. Both in-phase synchronous detectors and quadrature-phase synchronous detectors are used in circuit 17 as shown to synchronously convert the NTSC video carrier modulated to baseband. Synchronization is performed in the analog domain in specific circuit 17 to convert the NTSC video carrier The modulation is converted to baseband as shown therein, and the responses of in-phase synchronous detector 170 and quadrature-phase synchronous detector 171 used for this purpose are digitized using respective analog-to-digital converters 172 and 173 . The third local oscillator 174 in the circuit 17 provides the 0° phased oscillation to the in-phase synchronous detector 170 and the +90° phased oscillation or the -90° phased oscillation to the positive Cross-phase synchronous detector 171. The third local oscillator 174 is a controlled oscillator provided in the quadrature phase synchronous detector 171 in response to a phase control (AFPC) signal of an undesired low frequency component and an automatic frequency. Figure 9 shows the generation of an AFPC signal using a common Costa PLL configuration in which the responses of in-phase synchronous detector 170 and quadrature-phase synchronous detector 171 are filtered by low-pass filters 176 and 177, mixed in mixer 178 The responses of low pass filters 176 and 177, and the output of mixer 178 is filtered by low pass filter 179 to generate the AFPC signal for third local oscillator 174.

Additionally, synchronizing the NTSC video carrier modulation to baseband can be performed in the digital range after conversion to a final IF band just above baseband, so that the final IF can be digitized. This avoids any problems with the analog-to-digital converters 172 and 173 being slightly different in conversion gain.

The digital response Q of the quadrature-phase synchronous detector 171 is the product of the single-sideband components of the NTSC signal (i.e., those components with frequencies above 750 KHz) plus the DTV signal as they appear in the output I of the in-phase synchronous detector 170. Hilbert conversion. The reader's attention is now returned to Figure 1. This Hilbert transform derived from the response Q of the quadrature phase detector in synchronization circuit 17 is phase shifted to provide a 90° lag for all frequencies above a few kilohertz. A finite impulse response digital filter is suitable for the inverting Hilbert transform circuit 18 as is well known in the art of digital television receivers.

In linear combiner 19 the inverting Hilbert transform response of circuit 18 is linearly combined with the digital response I of the in-phase synchronous detector to produce a luminance signal with a cutoff slightly above 750 KHz. Due to its single-sideband nature with reference to the NTSC video carrier frequency, this luminance signal typically does not contain DTV products. Whether the linear synthesizer 19 is an adder or a subtractor depends on whether the operation of the quadrature-phase synchronous detector is chosen to lead or lag the operation of the in-phase synchronous detector.

The output signal from the VHF intermediate frequency amplifier 12 is supplied to a quadrature phase synchronous detector 20 for modulating the NTSC video carrier describing the higher frequency portion of the composite video signal to baseband. Quadrature phase synchronous detector 20 provides a digital response Q'. As an example, if the quadrature-phase synchronous detector operates in the analog domain, an analog-to-digital converter is cascaded after the synchronous detector to digitize its output. Quadrature-phase synchronous detector 20 is provided from circuit 17 for synchronously converting NTSC video carrier modulation to baseband from the same source (ie from phase shifting network 175). The response Q' of the quadrature phase synchronous detector 20 is the single sideband component of the NTSC signal (that is, those components whose frequency is higher than 750KHz) plus a part of the product part of the DTV signal passed by the SAW filter in the intermediate frequency amplifier 6. A Hilbert transform. This Hilbert transform provided from the response Q' of the quadrature phase synchronous detector 20 is provided with a 90° lag by the inverting Hilbert transform circuit 21 at least at frequencies above about 500 KHz. This process produces a response identical to that of an in-phase NTSC video detector at the same higher frequencies, but exhibits a low frequency cutoff that complements the high frequency cutoff of the linear synthesizer 19 .

Linear combiner 22 combines the responses of linear combiner 19 and quadrature phase synchronous detector 20 to produce a full-band composite video signal which is applied to the image reproduction section 23 of the NTSC receiver for displaying on reproduced images. This portion 23 of an NTSC receiver typically includes sync separation circuitry and chrominance signal reproduction circuitry; in a combined NTSC and HDTV receiver circuitry would also include circuitry for adapting the 4:3 ratio NTSC image for display to DTV Image of the circuit shown on the 16:9 display.

In order to provide 90° lag for frequencies as low as a few kilohertz, the inverse Hilbert transform circuit 18 requires a substantial amount of waiting time (or insertion delay). Providing a 90° hysteresis to a frequency that is a fraction of the horizontal scan line frequency means that the products of the non-cancelled DTV signal will be of sufficiently low frequency that they can be suppressed by operation of the receiver AGC. A shim delay is required in linking the I signal from the synchronous circuit 17 to the linear synthesizer 19 to balance the latency for the I and Q signals supplied to the linear synthesizer 19 . The pad delay must be cascaded with the inverting Hilbert transform circuit 21 so that its latency is less than that of the inverting Hilbert transform circuit 18 . Making the inverting Hilbert transform circuit 21 identical to the inverting Hilbert transform circuit 18 makes it possible to avoid the need for such spacers. When this change is made, the circuit benefits from a simplified technique that removes the need for separate inverting Hilbert transform circuits 18 and 21 .

Figure 2 shows a television receiver capable of receiving NTSC analog TV signals as well as DTV signals resulting from this simplification. Units 18-22 of the television receiver of Fig. 1 are replaced by adder 24, inverse Hilbert transform circuit 25 and linear synthesis circuit 26, and adder 24 is used to combine the Q output signal of synchronization circuit 17 with the Q output signal of quadrature sync detector 20 'The output signals are combined, the inverse Hilbert transform circuit 25 responds to the total output signal from the adder 24, and the linear synthesis circuit 26 is used to combine the inverse Hilert transform circuit 25 response with the I output signal of the synchronous circuit 17 to produce a cut-off slightly Brightness signal above 750KHz. Due to their single-sideband nature referenced to the NTSC video carrier frequency, such luminance signals are generally incompatible with DTV products. If quadrature phase synchronous detector 20 and the quadrature synchronous detector in synchronous circuit 17 operate out of phase with each other, rather than in phase as previously assumed, then adder 24 is replaced by a subtractor to achieve a balanced operation.

An advantage of synchronous detection of video high frequencies using a quadrature phase video carrier is that the overlap between video low frequencies and video high frequencies is automatically corrected. Additionally, overlap may occur at the highest video frequencies so the cancellation of DTV artifacts tends to be as high frequency as possible.

Fig. 3 shows a modification of the television receiver of Fig. 1 which uses, instead of quadrature phase synchronous detector 20, an in-phase synchronous detector 27 to synchronize the detection of the video high frequencies. The quadrature phase synchronous detector 20, the inverse Hilbert transform circuit 21 and the linear synthesizer 22 are omitted. Lap filter 28 low-pass filters the response of linear combiner 19 and high-pass filters the I' output signal of in-phase synchronous detector 27 before combining them linearly to produce a full With the composite video signal, this section 23 is used to reproduce the image on the display screen. The overlap frequency of the low-pass filtering and high-pass filtering cutoffs in the overlapping filter 28 is preferably at least 500 KHz. Since the receiver of FIG. 2 does not require overlapping filters 28, the television receiver of FIG. 2 has more economical hardware than the receiver of FIG.

Assume in Fig. 1, Fig. 2 and Fig. 3 television connection that the chrominance demodulation circuit is included in the image reproducing section 23 of the NTSC receiver for reproducing images on the display screen, so that the chrominance signal is supplied from the The image reproduction section 23 of the NTSC receiver which reproduces the image on the display screen is separated from the full-band composite video signal. However, another possibility is to separate the chrominance signal from the high frequency component of the composite video signal before the high frequency component of the composite video signal is combined with the low frequency component of the composite video signal.

FIG. 4 shows a variation of the television receiver of FIG. 3 having a conventional chromatic demodulation circuit 29 connected to respond directly to the baseband video high frequency detected by the in-phase synchronous detector 27. FIG. The chrominance demodulation circuit 29 is shown separate from the NTSC receiver section 30 for reproducing images on a display screen. Chrominance demodulation circuit 29 provides the color difference signal to section 30 of the NTSC receiver which receives the full-band composite video signal from overlapping filter 28 .

FIG. 5 shows a variation of the television receiver of FIG. 3 in which the chrominance demodulation circuit 29 is connected to respond directly to the baseband video detected by the quadrature phase synchronous detector 20 . Since the color burst is phase-shifted by 90° like other chrominance signal components, the Hilbert transform of the chrominance signal instead of synchronous detection of the actual chrominance signal has no essential influence on the recovery of the color difference signal.

The difference between Fig. 6 television receiver and Fig. 2 TV receiver is that the UHF band intermediate frequency amplifier 31 replaces the UHF band intermediate frequency amplifier 5, the second detector 32 replaces the second detector 8 of NTSC video low signal, and the VHF band intermediate frequency amplifier 33 replaces VHF band IF amplifier 11. Wherein, the VHF band intermediate frequency amplifier 31 has a passband suitable for the entire spectrum of the VSB AM NTSC video carrier modulation, the second detector 32 has a passband suitable for the entire spectrum of the VSB AM NTSC video carrier modulation, and the VHF band intermediate frequency amplifier 33 Has a passband suitable for the entire spectrum of VSB AM NTSC video carrier modulation. Figure 10 shows the desired overall response of the receiver at the output of the VHF intermediate frequency amplifier 33 with reference to the lower frequencies of the original transmission channel. This full bandwidth response allows the UHF band IF amplifier 6, the NTSC video high signal second detector 9, the VHF band IF amplifier 12, the NTSC video high signal quadrature phase synchronous detector 20, and the inverting Hilbert transform circuit 21 to be eliminated entirely. . Conversely, high pass filter 34 extracts the video high frequencies applied to linear synthesizer 22 from the response of inverse Hilbert transform circuit 18 for linear synthesis with the video low frequencies provided by linear synthesizer 19 .

The difference of Fig. 7 television receiver and Fig. 3 TV receiver is: have the UHF band intermediate frequency amplifier 31 of the passband that is suitable for the whole frequency spectrum of VSB AM NTSC video carrier modulation to replace UHF band intermediate frequency amplifier 5; Have suitable VSB AM NTSC video carrier modulation The second detector 8 of the passband of the entire spectrum of the entire spectrum replaces the second detector 8 of the NTSC video low signal; . Figure 10 shows the desired overall response of the receiver at the output of the VHF intermediate frequency amplifier 33 with reference to the lower frequencies of the original transmission channel. This full bandwidth response allows the UHF band IF amplifier 6, NTSC video high signal second detector 9, VHF band IF amplifier 12 and NTSC video high signal in-phase sync detector 27 to be omitted entirely. Conversely, the response I of the in-phase synchronous detector in synchronization circuit 17 is supplied to overlap filter 28 to provide it with a video high signal.

In some variants of the television receiver of FIG. 1, the chrominance demodulation circuit may be arranged to respond directly to the quadrature phase synchronous detector 20 or the inverse Hilbert transform circuit 21 response. In some variants of the TV receivers of Figures 6 and 7, the chrominance demodulation circuit may be arranged to respond directly to the I output signal or the Q output signal of the synchronization circuit 17 or directly to the response of the inverse Hilbert transform circuit 18; if These arrangements can also be made in the TV receivers of FIGS. 1 , 2 and 3 by changing their video low signal IF amplifiers to have an overall response of full baseband as shown in FIG. 10 .

Since the digital TV signal is random from scanning line to scanning line, and the chrominance signal tends to show strong line-line non-correlation before demodulation and strong line-line correlation after demodulation, so through horizontal Filtering reduces the effect of co-channel interfering digital signals on the chrominance demodulation results (like other forms of random noise). The above-mentioned NTSC receiver can be combined with the digital television receiver described in the applicant's patent application number 08/821,944 filed on March 21, 1997, wherein the patent title is "Use in a digital receiver from Auxiliary detection of NTSC interference in video signals from analog TV receivers". Knowing the foregoing disclosure, a person skilled in the art of television receiver design can easily make modifications to the television receivers disclosed so far that use PAL signals or SECAM signals instead of NTSC signals. While the foregoing disclosure describes NTSC television receivers that reproduce audio and video, the present invention is applicable to NTSC television receivers that do not reproduce audio and video, such as those incorporated in video cassette recorders or in NTSC signal cancellation filters. used in digital television receivers. A person skilled in the art of television receiver design can design many variations of receivers as described in the preferred embodiment, knowing the foregoing disclosure, and when the scope of the following claims is clarified, it is necessary remember.

Claims (20)

1. A video signal receiver having reduced sensitivity to interference from co-channel digital television signals, said video signal receiver comprising: A first input circuit for selecting a vestigial sideband AM signal describing a video signal, converting said selected vestigial sideband AM signal into a first intermediate frequency signal, and amplifying said first intermediate frequency signal to provide an already The amplified first intermediate frequency signal, the vestigial sideband amplitude modulation signal initially received by the first input circuit includes a video carrier and full sideband in addition to a vestigial sideband, and the vestigial sideband amplitude modulation signal is derived from A selection of channels, one or more of which will occasionally contain co-channel interference from a digital television signal; It is characterized in that the video signal receiver also includes: A video synchronization circuit for synchronously detecting the amplified first intermediate frequency signal according to the video carrier signal and according to a carrier having a phase difference of 90° from the video carrier signal, for generating a first in-phase synchronization detection responses and for generating a first quadrature-phase synchronous detection response; a first phase shifting circuit for 90° phase shifting all frequency components of said first quadrature phase synchronous detection response above a predetermined frequency to generate a first phase shifting circuit response; a first linear synthesis circuit linearly combining said first in-phase synchronous detection response with said first phase shifting circuit response to recover said full sideband and said vestigial sideband the lower frequency portion of said video signal, which does not contain any co-channel interfering digital television signals; and Circuitry for recovering higher frequency portions of said video signal depicted on said full sidebands but not on said vestigial sidebands. 2. A video signal receiver as claimed in claim 1, wherein said first input circuit selects said vestigial sideband AM signal describing a video signal so as to include the entirety of said vestigial sideband and extend from the video carrier to at least 1.75MHz part of the full sideband. 3. A video signal receiver as claimed in claim 2, further comprising: circuitry for recovering the higher frequency portion of the video signal depicted in the full sideband rather than in the vestigial sideband; and A second linear synthesis circuit for restoring the video signal by linearly combining the lower frequency portion of the video signal with the higher frequency portion of the video signal. 4. A video signal receiver as claimed in claim 3, wherein said circuit for recovering the higher frequency portion of said video signal comprises: A second input circuit for selecting a portion of said full sideband of said vestigial sideband modulated signal, converting the selected portion into a second intermediate frequency signal and amplifying said second intermediate frequency signal to provide an amplified second IF signal; a synchronous detector for synchronously detecting said amplified second intermediate frequency signal according to said carrier having a phase difference of 90° from said video carrier signal, for generating a second quadrature phase synchronous detection response ;and second phase shifting circuit for 90° phase shifting all frequency components of said second quadrature phase coherent detection response above a predetermined frequency to generate one for recovering said higher frequency portion of said video signal The second phase shifting circuit responds. 5. A video signal receiver as claimed in claim 2, further comprising: a second input circuit for selecting a portion of said full sideband of said vestigial sideband AM signal, converting the selected portion into a second intermediate frequency signal and amplifying said second intermediate frequency signal to provide an amplified second intermediate frequency Signal; a synchronous detector for synchronously detecting said amplified second intermediate frequency signal based on said carrier which is 90° out of phase with said video carrier signal for generating a second quadrature phase synchronous detection response ;and an adder for adding said second quadrature-phase synchronous detection response to said first quadrature-phase synchronous detection response to be applied to said first phase shifting circuit, said first phase shifting circuit to high all frequency components of said first and said second quadrature phase coherent detection responses at a predetermined frequency are phase shifted by 90° to produce said first phase shifting circuit response; said first phase shifting circuit response determines said first linear synthesis circuit for recovering, in addition to said lower frequency portion of said video signal described both on said full sideband and on said vestigial sideband, The higher frequency portion of the video signal on the full sideband but not on the vestigial sideband is recovered. 6. A video signal receiver as claimed in claim 2, further comprising: a second input circuit for selecting a portion of said full sideband of said vestigial sideband AM signal, converting the selected portion into a second intermediate frequency signal and amplifying said second intermediate frequency signal to provide an amplified second intermediate frequency Signal; a synchronous detector for synchronously detecting said amplified second intermediate frequency signal based on said video carrier signal for generating a second in-phase synchronous detection response for recovering said higher frequency portion of said video signal; and an overlap filter for restoring the video signal by combining the lower frequency portion of the video signal with the higher frequency portion of the video signal. 7. A video signal receiver as claimed in claim 1, further comprising: A second linear synthesis circuit for restoring the video signal by linearly combining the lower frequency portion of the video signal with the higher frequency portion of the video signal. 8. A video signal receiver as claimed in claim 7, wherein said circuit for recovering the higher frequency portion of said video signal comprises: A second input circuit for selecting said full sideband portion of said vestigial sideband AM signal, converting the selected portion into a second intermediate frequency signal and amplifying said second intermediate frequency signal to provide an amplified second IF signal; a synchronous detector for synchronously detecting said amplified second intermediate frequency signal based on said carrier having a phase difference of 90° from said video carrier signal to generate a second quadrature phase synchronous detection response; and a second phase shifting circuit for phase shifting by 90° all frequency components of said second quadrature phase synchronous detection response above a predetermined frequency to generate said higher frequency portion for recovering said video signal A second phase shift circuit responds. 9. A video signal receiver as claimed in claim 1, further comprising: A second input circuit for selecting a portion of said full sideband of said vestigial sideband AM signal, converting the selected portion into a second intermediate frequency signal and amplifying said second intermediate frequency signal to provide an amplified second IF signal; a synchronous detector for synchronously detecting said amplified second intermediate frequency signal based on said carrier having a phase difference of 90° from said video carrier signal to generate a second quadrature phase synchronous detection response; and an adder for adding said second quadrature-phase coherent detection response to said first in-phase coherent detection response for application to said first phase shifting circuit, said first phase shifting circuit being higher than all frequency components of said first and said second quadrature phase synchronous detection responses at a predetermined frequency are phase shifted by 90° to produce said first phase shifting circuit response; said first phase shifting circuit response determines the said first linear synthesis circuit for restoring said lower frequency portion of said video signal described on said vestigial sideband in addition to said full sideband, also on said vestigial sideband The higher frequency portion of the video signal is depicted on the full sideband rather than on the vestigial sideband. 10. A video signal receiver as claimed in claim 1, further comprising: a second input circuit for selecting a portion of said full sideband of said vestigial sideband AM signal, converting the selected portion into a second intermediate frequency signal and amplifying said second intermediate frequency signal to provide an amplified second intermediate frequency Signal; a synchronous detector for synchronously detecting said amplified second intermediate frequency signal from said video carrier signal for generating a second in-phase synchronous detector for recovering said higher frequency portion of said video signal response; and an overlap filter for restoring said video signal by combining said lower frequency portion of said video signal with said higher frequency portion of said video signal. 11. A video signal receiver as claimed in claim 1, wherein said first input circuit selects the entire said vestigial sideband AM signal describing a video signal but discards the accompanying in-channel audio signal and any synchronous interference Pilot tone for a digital video signal. 12. A video signal receiver as claimed in claim 11, further comprising: a high pass filter providing a high pass filtered response to said first phase shifting circuit response; and a second linear synthesis circuit for restoring said video signal by linearly combining said lower frequency portion of said video signal with said high pass filter response to said first phase shifting circuit response. 13. A video signal receiver as claimed in claim 11, further comprising: an overlap filter for recovering the video signal. 14. A video signal receiver as claimed in claim 1, wherein said first input circuit comprises: a first detector for selecting a single one of said plurality of channels and converting an NTSC signal therein into a UHF IF signal; a first amplifier providing frequency-selective amplification to a portion of said UHF IF signal to produce a first amplifier response comprising a response to said vestigial sideband, said video carrier, and a relatively at least a portion of said full sideband response in the low frequency portion; a second detector for converting said first amplifier response into a first VHF IF signal; a second amplifier providing frequency selective amplification to said first VHF IF signal to produce a second amplifier response provided from said first input circuit as an output signal to said video and including a response to said vestigial sideband, said video carrier, and at least a portion of said full sideband describing a lower frequency portion of said video signal. 15. A video signal receiver as claimed in claim 14, further comprising: a third amplifier providing frequency-selective amplification to a portion of said UHF IF signal to generate a third amplifier response to only a portion of said full sideband; another second detector for converting said third amplifier response into a second VHF IF signal; a fourth amplifier providing frequency selective amplification to said second VHF IF signal to produce a fourth amplifier response for only a portion of said full sideband provided as an output signal from said second input circuit. 16. A video signal receiver as claimed in claim 15, further comprising: a synchronous detector for synchronously detecting said fourth amplifier response based on said carrier being 90° out of phase with said video carrier signal to generate a second quadrature phase synchronous detection response; second phase shifting circuit for phase shifting by 90° all frequency components of said second quadrature phase synchronous detection response above a predetermined frequency to generate a higher frequency portion for recovering said video signal a second phase shifting circuit response; and A second linear synthesis circuit for recovering the video signal by linearly combining the lower frequency portion of the video signal with the higher frequency portion of the video signal. 17. A video signal receiver as claimed in claim 15, further comprising: a synchronous detector for synchronously detecting said fourth amplifier response based on said carrier being 90° out of phase with said video carrier signal for generating a second quadrature phase synchronous detection response; and an adder for adding said second quadrature phase coherent detection response to said first quadrature phase coherent detection response for application to said first phase shifting circuit, said first phase shifting circuit having all frequency components of said first and said second quadrature phase synchronous detection responses above a predetermined frequency are phase-shifted by 90° to produce said first phase-shifting circuit response; said first phase-shifting circuit response determines with said first linear synthesis circuit for recovering, in addition to said lower frequencies of said video signal described both on said full sideband and on said vestigial sideband, There are said higher frequencies of said video signal depicted on said full sidebands but not on said vestigial sidebands. 18. A video signal receiver as claimed in claim 15, further comprising: a synchronous detector for synchronously detecting said fourth amplifier response from said video carrier signal for generating a second in-phase synchronous detection response for recovering the higher frequency portion of said video signal; and an overlap filter for recovering said video signal by combining said lower frequency portion of said video signal with said higher frequency portion of said video signal. 19. A video signal receiver as claimed in claim 14, further comprising: a high pass filter providing a high pass filtered response to said first phase shifting circuit response; and and a second linear synthesis circuit for recovering said video signal by linearly combining said lower frequency portion of said video signal with said high pass filtered response to said first phase shifting circuit response. 20. A video signal receiver as claimed in claim 14, further comprising: an overlap filter for recovering the the video signal.

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