MXPA98009523A - Cross channel intermodulator distortion correction device for transmitters ntsc television transmissions / canalsadyacen dtv - Google Patents

Abstract

When the analog and digital television signals are amplified by the same high-power amplifier, in a television transmitter of analog format and digitally formed, intermodulation distortion (IMD) is caused by a digital television signal (DTV), which occupies a channel that is immediately below and adjacent to a television signal of analogous format (e.g., NTSC). This cross-channel intermodulation distortion must be corrected. The correction of the intermodulation distortion can be achieved by essentially pre-correcting for the radio frequency (RF) intermodulation distortion by processing the corresponding television DTV and NTSC signals at the intermediate frequency (IF). Preferably, the pre-correction is achieved by diverting the DTV IF signal and using it to compensate in advance for the expected intermodulation distortion in the radio frequency, which is inherent in the NTSC signal.

Description

CONFIGURATION TO USE WHEN LESS AN AUXILIARY ANTENNA FOR PROVIDE DIFFERENT RADIATION PATTERNS FOR SIGNALS NTSC AND DTV TELEVISION OF ADJACENT CHANNELS TRANSMITTED FROM A MAIN ANTENNA COM N CROSS REFERENCE TO THE RELATED APPLICATION This application is a partial continuation (CIP) of the Application of the United States of America Number 09 / 050,109, filed on March 30, 1998, which is hereby incorporated herein by reference in its entirety. .

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to television transmitters. More specifically, the invention relates to television transmitters in which the adjacent channel television signals, especially adjacent NTSC and DTV channel signals (digital television) are transmitted from a main antenna, but in which the component signals from the Two channels are routed differently through the use of one or more auxiliary antennas. 2. Related Technique Since the 1980s, the use of a single amplifier has been used to amplify the visual and auditory components of an NTSC television signal, when high energy UHF tetrophys were developed and klystrode / IOT devices were introduced (inductive tube of exit, by its abbreviations in English). The inductive outlet tube has been used, as well as the tetrode and its derivative, the ® diachronous, in the common amplification (that is, amplification using a single amplifier) of elements within the NTSC signal. With the advent of DTV (digital television), the Federal Communications Commission (FCC) of the United States of America has distributed television channels in such a way that it has resulted in many radio broadcasters have their respective DTV channels allocated immediately above their NTSC channels in the frequency spectrum (called the "n + 1" situation), or immediately below their respective NTSC channels (the "nl" situation). Broadcasters want to add DTV broadcast capability to their NTSC streaming ability, as cheaply as possible. However, the immediate adjacency of the related NTSC and DTV channels has given rise to technical problems that were not present in the simple NTSC channels. The problems that arose from the NTSC-DTV configuration of the adjacent channel are largely based on a combination of demanding requirements, including the smoothing of the antenna response over a wider bandwidth (12 MHz in the United States). United States, 16 MHz in most countries outside the United States of America), and the energy combination of the two transmitters, with a channel combiner where there is little or no backup band. It has been thought that the presence of situations n + 1 and n-l under the channel assignments of the Federal Communications Commission, requires separate amplifiers for the NTSC and DTV signals, even if a single antenna were used to transmit both signals. On the other hand, if the NTSC and DTV signals were generated separately, without using a common frequency reference to keep the signals in phase, additional problems would arise in the transmitted signals. In situation nl, in which a small backup band is present between the DTV channel (lower) and the NTSC (upper) channel, it is possible to provide a channel combination filter system to allow the two signals to be transmitted in a common antenna. But in the n + 1 situation, there is virtually no backup band between the NTSC channel (lower) and the DTV channel (upper): there is a sparse gap (200 KHz) between the audio carrier deviated from the NTSC signal (in the upper end of the NTSC channel) and the lower edge of the DTV channel. Especially in situation n + 1, therefore, it is not practical to use a filter combiner implementation at the entrance to a NTSC / DTV transmission antenna. Different systems are known including NTSC, DTV, or combination signals, including U.S. Patent Number 5,532,748 (Naimpally), U.S. Patent Number 5,412,426 (Totty), U.S. Pat. United States of America Number 5,200,709 (Saito et al.), U.S. Patent No. 5,148,279 (Gabor), U.S. Patent Number 5,127,021 (Schreiber), U.S. Patent Number 5,019,788 (Fischer et al.), U.S. Patent Number 4,423,386 (Gerard), U.S. Patent Number 4,227,156 (Mattfeld), U.S. Patent Number 4,117,413 (Moog), and U.S. Pat. Patent of "the United States of America Number 4,045,748 (Filliman)." The Totty patent describes a simultaneous transmission of information. n NTSC video information HDTV, but accomplishes this by digitizing analog NTSC signals originally, before combining the result with the digital HDTV data. Naimpally describes a hybrid digital and analog television signal, in which an analog signal is combined with a digital signal, before the combination is transmitted (see the frequency domain diagram of Figure 4, and the two parallel paths in the circuit diagram in Figure 5). More generally, Gabor describes a television transmitter which is said to be capable of transmitting fifty channels simultaneously, using a common amplifier and a single antenna (see the power amplifier module in Figure 3). Schreiber describes a more complex television transmission system in which a television signal is first divided into several frequency components, before being combined again, and transmitting the combined signal. Fischer et al. And Satio et al. Seem to illustrate the general approach of providing separate amplification paths for signals of different frequency ranges. Finally, the patents of Mattfeld, Gerard, Filliman and Moog, describe systems that amplify the signals of different frequencies. Mattfeld provides a common AM / FM amplifier at the intermediate frequency; Gerard provides a distributed amplifier that is said to reduce intermodulation products; Filliman deals with the separation and recombination of frequency-based audio signal bands; and Moog describes an amplifier with several filters to emphasize different frequency ranges (especially, audio). However, none of these documents solves the problem described above, in relation to the efficient transmission of NTSC and DTV signals from adjacent bands. Therefore, there has been a need in the art to provide a system that allows broadcasters to transmit NTSC and DTV signals from adjacent bands in an acceptably clean manner, and to do so at minimal cost. On the other hand, even assuming that the problem described above has been solved by the methods described in U.S. Patent Application Number 09 / 050,109 (and repeated in the following Detailed Description), and that a single amplifier of two Wide channels directs a single antenna to simultaneously transmit the NTSC and DTV signals, another problem arises. The Federal Communications Commission has ordered that the radiation pattern of the two adjacent channel signals may have to be different. Field tests have shown that, because the reception and demodulation processes of the NTSC are substantially different from the reception and demodulation processes of the DTV, the multipath anomalies have different effects on the two types of signals. This phenomenon shows that there is a need in the art to address differently the NTSC and DTV signals that are transmitted from a common antenna.

In general, the techniques of addition and cancellation of antenna transmission patterns are known in the art. Conventionally, these techniques have been used where the tower structure of the antenna alters a designed radiation pattern, or where the antenna is in the presence of neighboring towers or antennas. Conventionally, addition or cancellation of the radiation lobe has been achieved by providing an auxiliary antenna close to a main antenna. A small amount (approximately one to ten percent) of the energy is coupled from the transmission line that feeds the main antenna. The signal coupled in phase and amplitude is adjusted before feeding to the main antenna. The auxiliary antenna is placed so that its own radiation pattern is added or subtracted from the radiation pattern of the main antenna, in a particular direction (horizontal) and / or elevation (vertical) or angle of inclination. Although this conventional addition and override configuration is useful for simple signals, this configuration is not suitable for directing signals having components that must be addressed differently. In particular, the known addition and override configurations can not direct an NTSC signal differently from that of an adjacent channel DTV signal (as described in the Detailed Description below), which is being transmitted from the same antenna. This is because two "adjacent" channel signals that are transmitted only from the same antenna must have the same radiation pattern.Thus, in a conventional manner, feeding the two components of a composite signal to an auxiliary antenna, it would simply be impossible to shape the radiation pattern of a component signal, without also affecting the radiation pattern of the other component's signal, this is because the signals are too close in frequency to allow for significant differentiation, especially in the UHF band (television channels 14-69) .The known systems do not seem to have solved or even recognized this problem.United States Patent Number 5,497,166 (Mahnad ) and United States Patent Number 5,414,437 (Mahnad), describe a frequency antenna oble, and specifically mentions that the HDTV will be sent to an antenna that is separated from the NTSC antenna; however, the separate address of the components of a composite signal is not described. U.S. Patent No. 5,504,495 (Bendov), discloses an antenna system that is designed to facilitate the conversion of NTSC to a "stacked" NTSC-and-HDTV transmission, and does not appear to be interested in the direction of a composite signal It appears that U.S. Patent Number 5,231,495 (Kaneko et al.), U.S. Patent Number 5,345,599 (Paulraj et al.), U.S. Patent Number 5,387,939 (Naimpally), U.S. Pat. of the United States of America Number 5,444,491 (Lim), U.S. Patent Number 5,557,333 (Jungo et al.) and U.S. Patent Number 5,559,808 (Kostreski et al.), are generally related to the use of more than one antenna, but they do not seem to describe the separate direction of the components of a composite television signal. Therefore, there is a need in the art to provide a practical configuration for directing in a different manner the NTSC and DTV signals that are transmitted from a common antenna. The present invention has been developed to meet this need.

COMPENDIUM OF THE INVENTION By means of the invention, it is not only practical to use a single high power amplifier, for the common amplification of signals from adjacent bands, but practical and economical. These adjacent band signals may include analog format signals such as NTSC signals, digital format signals such as DTV signals, in all combinations (NTSC / DTV, DTV / NTSC, NTSC / NTSC and DTV / DTV). On the other hand, the invention makes it possible for the different components of the transmitted composite signal to be directed differently. More specifically, the invention provides an apparatus for simultaneously transmitting signals of first and second television components (especially NTSC and DTV), which respectively occupy first and second channels that are immediately adjacent in frequency. The first and second television component signals have respective first and second radiation patterns, which are different from each other. The apparatus has a main antenna for transmitting a composite signal, including the signals of first and second television components (especially NTSC and DTV). The main antenna defines a composite radiation pattern. The apparatus also has at least one auxiliary antenna for transmitting a component bypass signal, which is derived from only one (NTSC or DTV, but not both) of the first and second television component signals. The auxiliary antenna defines a radiation pattern of the component which, when added to the composite radiation pattern that is defined by the main antenna, results in a combined radiation pattern in which the television signal of the first component has a pattern of radiation that is different from the radiation pattern of the television signal of the second component. The invention also makes it possible to provide two separate, separate auxiliary antennas for the television signals of the NTSC and DTV components, to provide an improved direction. Other objects, features and advantages of the invention will be apparent to those skilled in the art, after reading the following detailed description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is better understood if the following Detailed Description of the Preferred Modes is read, with reference to the figures of the accompanying drawings, in which like reference numbers refer to like elements in all respects, and in which: Figure 1 is a high-level functional block diagram, schematically illustrating the important elements of an exemplary, preferred embodiment of the present invention. Figure 2 illustrates the details of an exciter / transmitter 120 of the exemplary NTSC signal of the embodiment of Figure 1. Figure 3 illustrates the details of an exciter / transmitter 130 of the exemplary DTV signal of the embodiment of Figure 1. Figure 4 illustrates the details of an exemplary combiner 140 and amplifier 145 of the embodiment of Figure 1. Figure 5 shows an alternative to the embodiment of Figures 2-4, emphasizing an alternative implementation of the power level of the power connections. Automatic gain control feedback. Figure 6A illustrates a "modality of the inventive configuration for using two auxiliary antennas to provide different radiation patterns mutually to television signals NTSC and DTV from adjacent channels, transmitted from a common main antenna." Figures 6B and 6C illustrate two simpler modes each using only a single auxiliary antenna The mode of Figure 6B has only one NTSC 660 auxiliary antenna, and the embodiment of Figure 6C has only one DTV 661 auxiliary antenna.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES In describing the preferred embodiments of the present invention illustrated in the drawings, specific terminology is used for reasons of clarity. However, it is not intended that the invention be limited to the specific terminology that was selected, and it should be understood that each specific element includes all technical equivalents that operate in a similar manner to achieve a similar purpose. On the other hand, components and design procedures that are already known to those skilled in the art are omitted, for reasons of clarity. Referring to Figure 1, a high-level block diagram of a preferred embodiment of the present invention is illustrated schematically, with the conceptually less important components omitted for reasons of clarity. An NTSC signal driver / transmitter 120, receives an NTSC video signal (in the DC-to-4.2 MHz frequency range) and an audio signal, and provides a NTSC transmit-frequency signal (an RF signal in a assigned "N" channel), to a first input of a combiner 140. Analogously, a DTV signal (digital television) driver / transmitter 130 receives a bitstream (such as an MPEG bit stream adaptable with SMPTE 310M at 19.39 MHz), and provides a DTV signal adaptable by 8-VSB, transmission-frequency, to a second input of the combiner 140. The driver / transmitter 120 of the NTSC signal and the exciter / transmitter 130 of the DTV signal, operate under the timing of a common frequency reference 100 that helps the combined signals do not undesirably interfere with one another, as they would if they were not locked by phase. The combiner 140 linearly combines the transmission-frequency signals and provides a combined NTSC / DTV signal to a single high power amplifier 145. The single amplifier 145 drives a single transmission antenna 150 that transmits both the NTSC signal and the DTV signal. The characteristics of the amplifier are important to the invention, because, as introduced in the Background of the Invention, common wisdom would require two separate amplifiers and (possibly) two antennas, in a configuration that would have undesirable interference characteristics between the two signals. The invention of the applicant avoids the need for an additional amplifier and the undesirable interference characteristics that would be characteristic of conventional approaches for the problems of n + 1 and n-1. Figure 2 shows certain details of an exemplary embodiment of the exciter / transmitter of the NTSC signal of Figure 1. For reasons of clarity, the conventional features that are understood to be necessary or desirable for the implementation of the circuit are omitted. The exciter / transmitter 120 of the illustrated NTSC signal receives an NTSC video signal (in the DC-to-4.2 MHz frequency range) and an audio signal, and provides a NTSC transmit-frequency signal (an RF signal). on an assigned "N" channel) to the combiner (not shown in Figure 2). Those skilled in the art readily implement this total function, and it should be understood that the illustrated mode is shown by way of example and is not intended to limit the scope of the invention in any way. Additional details need to be provided, as many vendors provide commercially available products that perform this total function. Referring to Figure 2, the video processor 210 manipulates the input video signal to compensate, in advance, for the distortion that is expected to occur at the intermediate frequency (IF) and the radio frequency (RF, for its acronym in English) of the transmission to the modulated visual signal. The video processor 210 provides these compensation functions such as differential gain compensation and differential phase compensation and compensation without luminance linearity, to achieve response linearity. An NTSC modulator 220 receives the compensated video signal from the video processor 210, along with an associated audio signal. Essentially, the modulator modulates the video and audio signals on an intermediate frequency carrier from a phase locked cycle (PLL) 225, which is locked by phase to the common frequency reference 100. The The modulator can comprise, for example, a rudimentary sideband filter (VSB), implemented with surface acoustic wave (SA) technology. In any case, the NTSC 220 modulator outputs an intermediate frequency signal with NTSC standard visual and auditory bearers at carrier frequencies of 45.75 MHz and 41.25 MHz, respectively. The frequency reference 100 may include, for example, an oscillator 101 that provides a stable frequency reference signal (such as 10 MHz) to different circuit components by a signal splitter 102. Oscillator 101 can be implemented as an oscillator of temperature-controlled crystal, an oven-controlled crystal oscillator, a GPS reference signal (global positioning system), and the like. The signal splitter 102 can be any circuit that displays the reference signal, ensuring a constant phase relationship across all the circuits it drives. The NTSC IF signal of the modulator 220 is previously distorted by an NTSC IF 230 processor to compensate for the distortion that is expected to occur at the radio frequency (RF) to the modulated NTSC signal. The NTSC IF 230 processor can compensate for these undesirable phenomena such as intermodulation distortion, cross-modulation distortion, and incidental distortion of carrier phase modulation, and the like, resulting in a compensated signal, modulated purely by amplitude, which is desirable. . The previously compensated NTSC IF signal is provided to the IF-to-transmission-frequency converter 240. The IF-to-transmission-frequency converter 240 also receives a sinusoidal carrier of a given frequency by the desired transmission frequency of the particular transmission "N" channel, such as in the UHF range, which is assigned to the transmission site involved. . The carrier is provided by a phase locked cycle (PLL) 250, which is locked by phase to an output of the frequency reference 100. The IF-to-transmission frequency converter 240 includes a mixer that provides a signal Modulated low energy NTSC (eg, one watt), on the transmission frequency of Channel N. Converter 240 inverts the frequency order of the auditory and visual components of this modulated NTSC signal, transmit frequency, low energy , so that the carrier of the visual component is now below the carrier of the auditory component, in accordance with transmission standards. A series of amplifiers, shown by the intermediate power amplifier 260 (IPA, for its acronym in English) and the impeller amplifier 270, amplify the modulated NTSC signal, transmission frequency, low energy, from the converter 240 at an energy level closer to the energy levels of the transmission. For example, the driver amplifier 240 can output an average peak energy signal of 2.5 kW in synchronization, with a hearing power of 125. This signal is provided to the first input of the combiner 240 shown in Figures 1 and 4. Preferably, the output of the signal to the combiner is subjected to automatic gain control (AGC, for its acronym in English). For this purpose, an example of an automatic gain control feedback path from the output of the impeller amplifier 270 to the IF-to-transmission-frequency converter 240 is provided. The control system of the gain control that can be of conventional design, and that is located inside the converter 240, ensures that the NTSC signal of substantially constant energy level is provided to the combiner. Referring now to Figure 3, details of an exciter / driver 130 of the exemplary DTV signal (Figure 1) are shown by way of illustration and do not limit the scope of the invention. As with the description of the exciter / driver of the NTSC signal of Figure 2, the following description omits conventional elements known to those skilled in the art, with the understanding that commercially available products perform the same total function performed by Figure 3. In addition, the present description is abbreviated because the functions performed by the elements 320, 325, 330, 340, 350, 360, 270, 375 and 377 of Figure 3, are analogous to the functions of the elements 220, 225, 230, 240, 250, 260, 270, 275 and 277 of Figure 2. Referring again to Figure 3, a modulator 320 receives a carrier frequency signal that is locked per phase by phase lock cycle 325 to a reference carrier, from the frequency reference element 100 (Figures 1 and 2). The modulator 320 also encodes an MPEG bit stream adaptable by SMPTE 310M, of 19.39 MHZ, and modulates a pilot carrier to 46.69 MHZ in accordance with (for example), the 8-VSB standard accepted by the Federal Communications Commission for transmission land. Modulator 320 outputs an intermediate frequency analog signal with a pilot carrier at 46.69 MHZ, on the upper edge of the 41-47 MHZ band designated for television signals at the intermediate frequency. __ A DTV IF 330 processor processes the intermediate frequency signal from the modulator, performing previously analogous pre-compensation and pre-conditioning functions, performed by the 23-0 processor (Figure 2) for the NTSC signals. However, the DTV IF 330 processor is preferably implemented as a digital signal processor (DSP), to perform the pre-compensation and pre-conditioning functions on a digitally contained signal, using techniques (such as finite impulse response filters) that are better suited for the processing of these signals. In any case, the DTV IF 330 processor provides a pre-compensated and pre-conditioned signal to an IF-to-transmission-frequency converter 340. The IF-to-transmission-frequency converter 340 converts the analog intermediate frequency signal from the DTV IF processor to a transmit-frequency signal. In the preferred application of this invention, in which the DTV channel is immediately adjacent to the corresponding NTSC channel in the frequency spectrum, in accordance with the channel assignments of the Federal Communications Commission, two situations are encountered. The "n-1" situation includes a DTV channel that is immediately below the NTSC channel, and the "n + 1" situation includes a DTV channel that is immediately above the NTSC channel. In FIG. 3, therefore, the IF-to-transmission-frequency converter 340 is illustrated as providing a signal in Channel Nl or Channel N + 1, where "N" is the channel assigned to the corresponding NTSC channel in FIG. Figure 2. Essentially including a mixer, the converter 340 receives a sinusoidal carrier signal from a phase locked cycle 350 which is driven by the frequency reference element 100 (Figures 1, 2), to be modulated by the DTV signal IF. The operation of the converter results in an inversion of the order of the frequency of the DTV signal. The pilot carrier is changed from the upper end of the channel (46.69 MHZ is close to 47 MHZ) to the lower end of the channel at the transmission frequencies. It is notable that, in situation n-1, this placement of the DTV signal at the lower end of the DTV channel places it at only 200 kHz away from the deflected NTSC auditory carrier. The converter 340 provides a low energy signaltransmitter-frequency, to a series of amplifiers, which are shown in Figure 3 as including an intermediate power amplifier (IPA) 360 and an impeller amplifier 370. The impeller amplifier 370 provides the combiner of Figure 1, an adaptive DTV signal of 8-VSB, in Channel Nl for the allocation status of channel "nl" or in Channel N + l for the channel allocation situation "n + l". The signal from the driver amplifier 370 is of a sufficient energy level to drive the high power amplifier 145 to provide the output energy of the transmission. A feedback path 145 of automatic gain control is provided from the output of the impeller back to the converter 340, which ensures that the signal provided to the combiner is of substantially a constant energy level. Referring now to Figure 4, a preferred implementation of the combiner 140 and the high power amplifier is illustrated. The combiner 140 is preferably implemented as a conventional quadrature hybrid combiner of the type discussed in detail in commonly assigned U.S. Patent No. 4,804,931, issued in 1989, and which, by integrity, is incorporated into the present as a reference. As those skilled in the art readily appreciate, hybrid combiners are four-port devices that have two outputs, each of which receives half the signal energy from each of the two inputs of the combiner. Thus, an undesirable characteristic of hybrid combiners is that, when the signals at their inputs are incoherent, the hybrid combiners divide the energy of each input signal. In the present use of the hybrid combiners, half the energy of each input signal is provided to the high power amplifier 145, while the other half of the energy of each input signal is wasted through the dissipation in the resistor 141 to the ground, despite the loss of energy to the resistor 141, the desirable linearity of the hybrid combiner, and the isolation of the input signals from one another to avoid by the same an undesirable mixing of the two inputs, a preferred implementation is made for the combiner 140. The high power amplifier 145 is an essential element of the invention, since it satisfies the demand for response raid (less than 1 dB) through a wideband amplitude of two channels (12 MHZ in the United States of America, 16 MHZ in most countries outside the United States of America), and the significant energy requirement to the signals NTSC + DTV with minimal inter-channel interference. The invention makes it easier for a device of a tetrode type, and especially a diacid amplification device such as a Thomson TH-680, to provide optimum performance for this application. Tetrode and diacritical implementations are preferred because of their ability to operate with cavity sections that can be tuned to wide bandwidths (two-channel width), to exhibit sufficient linearity so that cross-modulation and correction can be corrected. Intermodulation distortion, with established methods, and to provide significant transmission energy levels. Of course, the scope of the invention should not be limited to the solutions of the tetrode and the diacrum; Alternative implementations, such as those that include solid state amplifiers, also fall within the intention of the invention. The diachronic or tetrode energy amplifier can be replaced by a suitable wide-band solid-state amplifier, using an appropriate number of RF energy transistors to reach the required energy, and can operate advantageously in the two UHF and VHF bands . In an exemplary embodiment to which the invention should not be limited, the TH-680 can provide 104 kW of peak envelope energy, which can (as a non-limiting example) include the following distribution of energy levels. To reduce interference with channels outside the pair of adjacent channels, a suitable two-channel bandpass filter (BPF) (12 MHZ in the United States of America) is provided at the output of the amplifier 145. In order to comply with the transmission power standards, the amplifier 145 must amplify the combined NTSC + DTV signal, so that the bandpass filter provides an average synchronization signal peak energy (NTSC) of 25. kW, average NTSC hearing power of 1.25 kW, and average DTV energy of 2.5 kW. Of course, the variation of the above particulars, in accordance with commonly known principles, falls within the ability of those skilled in the art. As those skilled in the art readily appreciate, this amplifier includes a tube that performs energy amplification, as well as a resonator cavity that limits the range of frequency at which the tube amplifies the signals. For each assigned pair of adjacent channels (either Channel Nl through N, or Channel N through N + 1), one skilled in the art, after reading this specification, can easily implement, without undue experimentation, a tuned amplifier appropriately, using an appropriate device of the class of atrode and the cavity of the resonator. The implementation is different for each adjacent channel pair, but the design principles remain the same regardless of the particular assignment, and it is not necessary to provide additional details to illustrate the implementation and operation of the invention. For many applications, the high power amplifier 145 comprises a device of a tetrode class, especially a Thomson TH-680 device, available from Thomson Tubes Electronique. Table 1 shows some of the specifications of the TH 680, relevant to an exemplary NTSC application. It should be understood that the specifications are exclusively for one exemplary NTSC application, and that the scope of the invention should not be limited to a particular component or to a specific set of signal types.

The teachings of the invention can also be employed using Thomson TH-563 (with energy levels of half of those of TH 680 in Table 1), and TH-562 (with energy levels of one quarter of those of TH 680 in Table 1). The TH-610 is an air cooled diacrum (with energy levels of one sixth of those of the TH 680). Table 2 shows the tentative data showing the performance of the TH-610: Of course, one can choose the particular device used for a particular energy application (especially average energy at the synchronization peak), and the frequency response (preferably less than 1 dB variation across the entire frequency band). of two channels of interest) are found. Figure 5 illustrates an alternative implementation of the embodiment of Figures 2-4, emphasizing an implementation of the feedback settings of the alternative power gain automatic gain control, which ensures that the output power levels remain substantially constant . In Figure 5, the feedback paths 276 and 376 conducted from the transmit signal output by the bandpass filter 146, back to the respective IF-a-transmitters-frequency converters 240 and 240 are shown. The trajectories 276 and 376 are provided instead of the trajectories 275 and 375 (Figures 2 and 3, respectively). The bandpass filter 277 of the NTSC channel, and the bandpass filter 377 of the DTV channel, is provided in the feedback paths 276, 376, respectively, so that only the channel frequency components are returned to the converters 240, 340. Alternative feedback configurations operate with similar principles of feedback control, known to those skilled in the art. When the average energy rises from a desirable level of stable state energy, either at the outputs of the impeller amplifiers 270, 370, or at the filter outlet. of bandpass 146, the feedback configurations within the converters 240, 340, act to correct the variation to return the energy level at the sense point, back to the desirable level of stable state energy. The gain factor that the converters 240, 340 apply to the feedback signals in the paths 275, 375 or 276, 376, are different, and are determined by the differences in the magnitude of energy between the outputs of the driver amplifiers 270 , 370 and bandpass filter 146. However, the principles remain the same. In the embodiment shown in Figures 2 and 3, the gain correction is achieved locally (within the respective NTSC and DTV paths), and compensates only for the variations that occur through the amplification paths 260, 270 and 360, 370, respectively. However, the alternative implementation shown in Figure 5 achieves a more complete gain correction over the full path between the IF-to-transmission-frequency converters 240, 340, and the last output of the bandpass filter. 146. Thus, it is seen that a first aspect of the invention makes it possible for an amplifier to include preferably a tube of a tetrode class (such as a diacritic) and a cavity resonator chosen in an appropriate manner. The circuits provide signals of analogous format (for example, NTSC) and of digital format (for example, DTV) under the control of a common frequency reference. The input of the amplifier receives a signal from a device that combines the NTSC and DTV signals in a clean and linear manner in the frequency of the transmission, and amplifies the combined signal for transmission through a common antenna. In this way, the invention not only allows a single antenna to be used for the transmission of signals from adjacent channels of analog format and digital format, but also avoids interference between the components of the transmitted signal of analog format and digital format , by virtue of the substantial linearity of the combiner and the components of the amplifier.

A second aspect of the invention solves the problem of how to direct differently composite signals (especially NTSC / DTV), wide of two channels that are transmitted from a common antenna. As mentioned in the Background of the Invention, because the reception and demodulation processes of the NTSC are substantially different from the reception and demodulation processes of the DTV, the multipath anomalies have different effects on the two types of signals . The Federal Communications Commission has ordered that the radiation pattern of the two adjacent channel signals should be different. A basic concept of a solution to minimize the effects of multiple trajectories, would be to radiate each signal through different vertical inclination angles, and choose a radiation pattern of the horizontal NTSC signal, which is different from the radiation pattern of the DTV signal horizontal that is being transmitted from the same antenna. For example, this solution could include the address of the DTV signal within a group of skyscrapers, but pointing the main lobe of the NTSC signal next to tall buildings. You can choose the particular radiation pattern, based on the propagation studies that are based on the terrain and the structures that lie in the trajectories of the signals. Figure 6A illustrates one embodiment of the inventive configuration for using two auxiliary antennas, to provide different radiation patterns in a mutual manner for the television signals of adjacent channels that are transmitted from a common main antenna. In the configuration of Figure 6A, the reference numbers of the element refer to the elements numbered in a similar manner of Figures 1 to 5, and it is not necessary to repeat their description. Briefly, a commonly amplified composite NTSC-DTV signal is transmitted from a main antenna 150. Auxiliary antennas 660, 661 transmit the auxiliary signals NTSC and DTV, respectively. The sum of the signals of the antennas 150, 660, 661, determine the radiation pattern of the NTSC and DTV signals of simultaneous transmission. Referring to Figure 6A, a coupler 610 diverts a small percentage (from about one to about ten percent) of the energy of the output of NTSC exciter / driver 120. An amplifier 620 tuned to the N channel (the assigned NTSC channel), receives the signal diverted from NTSC. The amplified NTSC signal is adjusted per phase by the phase changer 630 and adjusted by level by the level adjuster 640, before reaching the auxiliary antenna 660 of the NTSC. Between the output of the phase / level adjusters, and the auxiliary antenna 660, there is a circulator 650 with a dummy load. The circulator absorbs the energy received by the auxiliary antenna 660 that has been radiated from the main antenna. The implementation and particular arrangement of the elements in the path between the coupler 610 and the antenna 660 can be varied, in accordance with the principles known to those skilled in the art. Therefore, the modality illustrated is purely exemplary in nature and should not serve to limit the scope of the invention. The antenna 150 transmits the composite signal NTSC + DTV, while the antenna 660 transmits a phased NTSC signal, adjusted by level, which affects the radiation pattern of the resulting transmitted signal. Can the radiation pattern be symbolized as: (NTSC + DTV) main? to «NTSCau? where ? denotes the addition of vector radiation patterns from the two antennas, and "a" is a fraction that indicates the degree to which the auxiliary NTSC signal is smaller than the NTSC component in the composite signal NTSC + DTV.

Those skilled in the art determine the level and phase adjustment of the auxiliary NTSC signal, as well as the value of the parameter "a", in accordance with the relative physical placement of the auxiliary antenna and the main antenna, and the propagation characteristic of the particular transmission area of interest. The elements 611, 621, 631, 641, 651, and 661, function for the high energy DTV signal, analogously to the operation of the elements 610, 620, 630, 640, 650, and 660 for the JJTSC signal of high energy, and it is not necessary to repeat the previous description. The antenna 661 transmits a phased DTV signal, adjusted by level that affects the radiation pattern of the resulting transmitted signal. Can the radiation pattern be symbolized as: (NTSC + DTV) main? b.DTVau? where ? denotes the addition of vector radiation patterns from the two antennas, and "b" is a fraction that indicates the degree to which the auxiliary DTV signal is smaller than the DTV component in the composite signal NTSC + DTV. Those skilled in the art determine the level and phase adjustment of the auxiliary DTV signal, as well as the value of the "b" parameter, in accordance with the relative physical placement of the auxiliary antenna and the main antenna, and the propagation characteristic. of the particular transmission area of interest. Figure 6A shows two auxiliary antennas 660, 661 to provide improved steering capability, to differentiate the radiation patterns of the component of the NTSC signal and the component of the DTV signal from the composite signal that is transmitted from the main antenna 150. However, only one of the two auxiliary antennas must be provided, in order to differentiate the radiation patterns of the components of the NTSC and DTV signals. Figures 6B and 6C illustrate two simpler modes that employ only a single auxiliary antenna. The embodiment of Figure 6B has only one auxiliary antenna 660 NTSC, and the embodiment of Figure 6C has only one auxiliary antenna 661 DTV. Any of the auxiliary antennas 660 or 661 alone, can perform the radiation pattern direction that is different for the NTSC and DTV signals, the composite signal of which is transmitted from the main antenna 150. Modifications and variations of the modalities are possible. which were mentioned above of the present invention, as will be appreciated by those skilled in the art in light of the above teachings. For example, the choice of components can be varied to achieve the functions described, the particular tuning methods (or programming) for the tunable (or programmable) elements, and the type and frequency of the signals to which the invention, in accordance with principles known to those skilled in the art, without departing from the scope of the present invention. Therefore, it should be understood that, within the scope of the appended claims and their equivalents, the invention may be practiced in another manner than that specifically described.

Claims (30)

1. CLAIMS 1. An apparatus for simultaneously transmitting signals of first and second television components that respectively occupy the first and second channels that are immediately adjacent in frequency, the signals of first and second television components having first and second radiation pans. second respective that are different from each other, the apparatus comprising: first supply elements for providing the signal of the first television component in the first channel, - second supply elements for providing the signal of the second television component in the second channel; elements for combining the signal of the first television component and the signal of the second television component, to provide a composite signal occupying the immediately adjacent first and second channels; a main antenna to transmit the composite signal, the main antenna defining a composite radiation pan; first deflection elements for diverting only one of the first and second television component signals, before the combination elements, to provide a signal deviated from the component; and an auxiliary antenna for transmitting the deviated signal of the component, the auxiliary antenna defining a composite radiation pan which, when added to the composite radiation pan of the main antenna, results in a combined radiation pan in which the signal of the First television component in the first channel, has the first radiation pan different from the second radiation pan of the signal of the second television component in the second channel.
2. 2. The apparatus in accordance with the claim 1, wherein: the signal of the first television component is a NTSC transmit-frequency signal; the signal of the second television component is a transmission-frequency DTV signal; the combined signal is a NTSC + DTV transmission-frequency signal, and the composite signal is a combined high-energy NTSC + DTV signal.
3. 3. The apparatus in accordance with the claim 2, characterized in that it also comprises: second deflection elements for diverting energy from a second of the signals of first and second television components before the combination elements, to provide a second signal deviated from the component; and a second auxiliary antenna for transmitting the second signal deviated from the component, the second auxiliary antenna defining a second radiation pan of the component that, when added to the composite radiation pan defined by the main antenna, and the combined radiation pan defined by the first auxiliary antenna, results in a second combined radiation pan in which the signal of the first television component in the first channel has the first radiation pan that is different from the second radiation pan of the component television signal second, in the second channel. The apparatus according to claim 2, wherein the first deflection elements include: a phase shifter that adjusts the phase of the deviated signal of the component. The apparatus according to claim 2, wherein the first deflection elements include: a level adjuster that adjusts the level of the signal deviated from the component. The apparatus according to claim 2, wherein the first deflection elements include: a circulator that absorbs the received energy through the auxiliary antenna. The apparatus according to claim 2, wherein the first deflection elements include: a phase shifter that adjusts the signal phase deviated from the component; a level adjuster that adjusts the level of the signal diverted from the component; and a circulator that absorbs the received energy through the auxiliary antenna. The apparatus according to claim 2, wherein: the two immediately adjacent transmission channels are UHF channels. 9. The apparatus in accordance with the claim 2, where: the two immediately adjacent transmission channels are VHF channels. 10. The apparatus according to claim 2, wherein: the first channel is below the second frequency channel. The apparatus according to claim 2, wherein: the first channel is above the second frequency channel. 12. The apparatus in accordance with the claim 2, where: each of the first and second channels is 6 MHz wide. 13. An apparatus for simultaneously transmitting first and second television component signals that respectively occupy the first and second channels that are immediately adjacent in frequency, the first and second television component signals having first and second radiation patterns respective which are different from one another, the apparatus comprising: a main antenna for transmitting a composite signal including signals of first and second television components, the main antenna defining a composite radiation pattern; and a first auxiliary antenna for transmitting a signal deviated from the derived component from only one of the signals of first and second television components, the auxiliary antenna defining a radiation pattern of the component which, when added to the composite radiation pattern defined by the main antenna, results in a combined radiation pattern in which the signal of the first television component in the first channel has the first radiation pattern that is different from the second radiation pattern of the signal of the second television component in the second channel. 14. The apparatus in accordance with the claim 13, wherein: the signal of the first television component is a NTSC transmission-frequency signal; the signal of the second television component is a transmission-frequency DTV signal; the combined signal is a NTSC + DTV transmission-frequency signal, and the composite signal is a combined high-energy NTSC + DTV signal. The apparatus according to claim 2, characterized in that it also comprises: first deflection elements for diverting the energy from the first of the signals of first and second television components, to provide the first signal deviated from the component; second diverting elements for diverting energy from a second of the signals of first and second television components, to provide a second signal biased from the component; and a second auxiliary antenna for transmitting the second signal deviated from the component, the second auxiliary antenna defining a second radiation pattern of the component which, when added to the composite radiation pattern defined by the main antenna and the combined radiation pattern defined by the first auxiliary antenna, 'results in a second combined radiation pattern in which the signal of the first television component has the first radiation pattern, which is different from the second radiation pattern of the second television component signal in the second channel . The apparatus according to claim 13, wherein the first deflection elements include: a phase shifter that adjusts the phase of the deviated signal of the component. The apparatus according to claim 13, wherein the first deflection elements include: a level adjuster that adjusts the level of the signal diverted from the component. 18. The apparatus according to claim 13, wherein the first deflection elements include: a circulator that absorbs the received energy through the. auxiliary antenna The apparatus according to claim 13, wherein the first deflection elements include: a phase shifter that adjusts the signal phase deviated from the component; a level adjuster that adjusts the level of the signal deviated from the component; and a circidler that absorbs the energy received through the auxiliary antenna. 20. The apparatus according to claim 13, wherein: the two immediately adjacent transmission channels are UHF channels. 21. The apparatus according to claim 13, wherein: the two immediately adjacent transmission channels are VHF channels. 22. The apparatus according to claim 13, wherein: the first channel is below the second frequency channel. 23. The apparatus according to claim 13, wherein: the first channel is above the second frequency channel. 24. The apparatus in accordance with the claim 2, where: each of the first and second channels is 6 MHz wide. 25. A method for simultaneously transmitting first and second television component signals that respectively occupy the first and second channels that are immediately adjacent in frequency, the first and second television component signals having first and second radiation patterns respective which are different from one another, the method comprising: on a main antenna, transmitting a composite signal including the first and second television components signals, the main antenna defining a composite radiation pattern; and on an auxiliary antenna, transmitting a signal deviated from the derived component from only one of the signals of first and second television components, the auxiliary antenna defining a radiation pattern of the component that, when added to the composite radiation pattern defined by the main antenna, results in a combined radiation pattern in which the signal of the first television component in the first channel has the first radiation pattern that is different from the second radiation pattern of the signal of the second television component in the second channel. 26. The method of compliance with the claim 25, wherein: the signal of the first television component is a NTSC transmit-frequency signal; the signal of the second television component is a transmission-frequency DTV signal; the combined signal is a NTSC + DTV transmission-frequency signal, and the composite signal is a combined high-energy NTSC + DTV signal. 27. The method according to claim 25, characterized in that it further comprises: deviation energy from the first of the signals of first and second television components, to provide the first signal deviated from the component; deflection energy from a second of the signals of first and second television components, to provide a second signal biased from the component; and on a second auxiliary antenna, transmit the second signal deviated from the component, the second auxiliary antenna defining a second radiation pattern of the component that, when added to the composite radiation pattern defined by the main antenna and the combined radiation pattern defined by the first auxiliary antenna, results in a second combined radiation pattern, which is different from the second radiation pattern of the signal of the second television component in the second channel. 28. The method according to claim 25, wherein: the two immediately adjacent transmission channels are UHF channels. 29. The method according to claim 25, wherein: the two immediately adjacent transmission channels are VHF channels. 30. The method according to claim 25, wherein: each of the first and second channels is 6 MHz wide.