MXPA01009009A - An upconverter for a television signal headend distribution center handling analog and digital signals and method of making and using the same - Google Patents

Abstract

An upconverter for converting IF television signals to VHF or UHF signals prior to broadcast is configured to process either analog or digital televison signals. The upconverter identifies the type of incoming television signal and generates an appropriate reference signal depending on whether the incoming televison signal is digital or analog. In an analog format, the reference signal is used by the modulator generating the IF signal to synchronize phase with the signals output by various other upconverters. In a digital format, the reference signal is used, for example, as a test signal for the upconversion circuit.

Description

ASCENDING CONVERTER FOR A TELEVISION SIGNAL ENTRY SECTION DISTRIBUTION CENTER THAT HANDLES ANALOG AND DIGITAL SIGNALS AND METHOD TO MANUFACTURE AND USER FIELD OF THE INVENTION The present invention relates to the field of the emission of television signals through aerial waves or through a cable network. More particularly, the present invention relates to an upstream converter for processing a television signal prior to its broadcast wherein the upstream converter is configured to process analog or digital split signals. BACKGROUND OF THE INVENTION Television signals, comprising an audio signal component and a video signal component, are emitted in the air through satellites or through cable networks. These signals are then received by televisions that present the signals as intelligible television programming. When television signals are originally generated, they are typically generated as intermediate frequency (IF) signals with a frequency of approximately 45 MHz in the electromagnetic spectrum. For television signals to be broadcast, either in the air or through a network of cables, and used by standard televisions, television signals must be converted to higher frequency signals in the very high frequency band (VHF). ) or in the ultra high frequency (UHF) band. This conversion is achieved through a device that is known as an up-converter. The up converter is located in the input section station where the television signals originate. The up converter takes the IF television signal, converts it into a VHF or UHF signal, and provides the converted signal for broadcast. In the television signal input section, an up-converter or a separate up-conversion circuit is used for each channel issued by the service provider. An example of an upconverter is illustrated in FIG. 1. The upconverter (100) receives an input IF television signal (101) provided to the conversion circuit (104). The conversion circuit (104) performs upconversion. The resulting VHF or UHF signal (102) is sent by the upstream converter (100). Traditionally, television signals have been analog signals. An analog television signal is based on a carrier wave (CW) at a specific frequency. Changes in the amplitude of the carrier wave that are known as modulations, are then made to carry the information of the television program encoded in the signal. Televisions respond to these modulations to generate the visualization of the broadcast television program. More recently, a trend has been developed to replace analog television signals with digital television signals. Digital signals can carry a greater volume of information with greater speed. Accordingly, the quality of the resulting image and the audio provided in a digital apparatus is significantly improved. The problem with the change to the digital format for the broadcasting of television signals is the need to replace the analogue broadcasting equipment and the existing analogue televisions with digital equipment. Accordingly, there is a need in the art for an upconverter that can easily process both digital and analog television signals before they are broadcast. This capability facilitates the transition from an analog signal format to a digital signal format. A particular problem for providing said double-mode up converter is the difference in the carrier frequency band between analog and digital broadcast formats. For example, in the analog format, television signals are carried by amplitude modulation of a base carrier wave. In North America, the base analog carrier wave has a frequency of 45.75 MHz. An upconverter operating in the analog format is shown in Figure 1. This upconverter (100) includes an oscillator (103) which sends a reference signal of 45.75. MHz. When numerous upstream converters are operated simultaneously to process various signals of television channels broadcast in the analog format, the phase of the various analog channel signals is preferably synchronized. This is known as the Harmonically Related Carrier Operation ("HRC"). In order to synchronize the phase of the channel signals, each upconverter (100) includes an identical oscillator (103) that can be synchronized with an external master reference. The oscillator (103) sends the reference signal (105) with the frequency of 45.75 MHz to the modulator (106) that is generating the input IF television signal (101). The upconverters for all the broadcast channels are typically interconnected through a control bus in order to coordinate their operation. Accordingly, the phase of the output IRF television signals of the various upstream converters can be coordinated. Unfortunately, this reference frequency required for HRC in the analog format (45.75 MHz) has no special meaning in the digital format. Digital signals are not simply modulated in amplitude, as in the case of analog signals, but use modulation systems such as quadrature amplitude modulation ("QAM") in which both the amplitude and the phase are modulated. In such a system, the analog reference frequency (45.75 MHz) is useless as a reference frequency for the modulator 106. Consequently, if the up-converter (100) is designed to process both analog and digital television signals, the Oscillator output (103) will be required for HRC operation in the analog format, but it will be useless or problematic in the digital format. Accordingly, there is a need in the art for an up converter and method for manufacturing and using it that more easily allows the up converter to process analog or digital television signals appropriately. COMPENDIUM OF THE INVENTION It is an object of the present invention to fulfill the requirements described above and others. Specifically, it is an object of the present invention to provide a rising converter and a method for manufacturing and using it that can process digital or analog television signals and produce a useful reference signal in any format. Additional objects as well as advantages and novel features of the invention will be presented in the following description or they can be obtained by those skilled in the art through the reading of these materials or the practice of the invention. The objects and advantages of the invention can be obtained through the means mentioned in the claims. In order to achieve these mentioned objects as well as other objects, the present invention can be incorporated and described as an up converter to convert the IF television signal into a VHF or UHF signal that processes digital or analog television signals with equal effectiveness. The upconverter of the present invention may include an upconversion circuit for receiving an input television signal and for producing a converted television signal; and a reference signal circuit for supplying a reference signal to a modulator external to the upconversion circuit. The reference signal circuit provides a first reference signal if the input television signal is an analog signal and provides a second reference signal if the input television signal is a digital signal. Preferably, the first reference signal has a frequency of 45.75 MHz and the second reference sequence has a frequency of 44 MHz. The reference signal circuit preferably includes a voltage controlled oscillator with an output range that includes both the first reference signal as the second reference signal. A phase-locked loop circuit is used to control the oscillator to produce either the first reference signal or the second reference signal. »A control circuit can automatically determine whether the input television signal is a digital signal or an analog signal and configure the phase-synchronized loop circuit accordingly to produce either the first reference signal or the second reference signal . The control circuit can sample the input television signal to determine whether the input television signal is analog or digital. Alternatively, the control circuit can receive a control signal indicating whether the input television signal is a digital or analog signal. The present invention also encompasses a method for upconverting an IF television signal to a VHF or UHF signal including the production of a first reference signal if the input split signals are an analog signal and a second reference signal if the input television signal is a digital signal. The method may also include determining with a control circuit whether the input television signal is a digital signal or an analog signal and selectively providing the first reference signal or the second reference signal in response. The method of the present invention preferably includes the steps of selectively generating the first reference signal or the second reference signal with a voltage controlled oscillator, controlling the oscillator with a phase-locked loop circuit, and configuring the loop circuit synchronized in phase according to whether the input television signal is a digital or analog signal with a control circuit. BRIEF DESCRIPTION OF THE DRAWINGS The attached drawings illustrate the present invention and form part of the specification. Together with the following description, the drawings demonstrate and explain the principles of the invention. Figure 1 is a block diagram for illustrating the principles of an up converter for a television broadcast input section. Figure 2 is a block diagram of an upgraded converter according to the principles of the present invention. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES As noted above for an up-converter system that processes digital television signals, the 45.75 MHz analog reference frequency has no meaning and is useless as a reference frequency. A more useful reference frequency for a system that processes digital television signals would be the center frequency of the IF band, 44 MHz. The IF frequency band is 41 to 47 MHz. For example, a reference frequency of 44 MHz , central in relation to the digital band, can be passed without modulation, in the upconversion circuit as a test signal. The use of a test signal of this type will be described later in greater detail. Using this principle, the present invention offers an up converter capable of generating one or two different reference signals as appropriate for the analog or digital format of the processed television signals. With reference to Figure 2, a preferred embodiment of the present invention will be explained below. Figure 2 illustrates an improved up converter (200) that solves the aforementioned problems of the prior art. The upconverter (200) is similar to a conventional upconverter in that an IF television signal (101) is received, processed by an upconverting circuit (204) and sent as a VHF and UHF (102) signal. A voltage controlled oscillator (203) is provided to generate a reference signal (205) supplied to a modulator (207) that generates the input IF signal (101). The voltage controlled oscillator (203) has a sufficient range to produce a reference signal (205) with a frequency of either 45.75 or 44 MHz. The voltage controlled oscillator (203) is controlled by a phase-locked loop circuit (201), which means that the phase-locked loop circuit (201) provides a particular voltage signal to the oscillator (203) which dictates the frequency of the output (205) of the oscillator (203). The loop circuit synchronized in phase (201), in turn, is configured by a control circuit (202). The control circuit (202) determines whether the input IF television signal (101) is a digital signal or an analog signal. If the input IF television signal (101) is an analog signal, the control circuit (202) configures the phase-locked loop circuit (201) in such a way that the control signal provided to the voltage controlled oscillator (203) causes the oscillator (203) to produce a reference signal (205). ) with a frequency of 45.75 MHz appropriate for the analog signal processed. This reference signal can then be used in operation HRC to synchronize the phase of the output signals from the various upconverters that provide different signals of television channels. Alternatively, if the control circuit (202) determines that the input IF television signal (101) is a digital signal, the control circuit (202) reconfigures in phase-locked loop circuit (201) to produce a signal of different reference. In this case, the voltage controlled oscillator (203) which responds to the phase-locked loop circuit (201) sends a reference signal (205) of 44 MHz to the upconversion circuit (204). This reference signal is more useful in the digital format, for example, since the 44 MHz signal is central to the digital band, it can be fed, without modulation, through the modulator (207) to the upconversion circuit (204) as a test signal. The sent signal (102) can be examined to determine if the upconversion circuit (204) is functioning properly. The control circuit 202 can determine whether the input IF signal 101 is a digital signal or an analog signal in any of several equivalent ways. For example, the control circuit (202) may be connected (207) to the input line of the IF signal (101). The control circuit 202 can then sample the incoming IF signal 101 to determine whether the signal 101 is a digital signal or an analog signal.

Alternatively, the control circuit 202 can receive an input signal 206 that indicates whether the input IF signal 101 is a digital signal or an analog signal. The input signal (206) can be generated, for example, through a user input device through which a human operator indicates whether digital or analog signals are being broadcast. The control circuit 202 is preferably a component of microprograms. As will be readily appreciated by those skilled in the art, the provision of two different reference signals to the upconversion circuit, depending on the digital or analog nature of the incoming processed IF signal, can be achieved through several equivalent devices including several programmatic components. , microprograms and equipment, any of these arrangements is within the scope of the present invention. The above description has been presented only to illustrate and describe the invention. It is not intended to be complete or to limit the invention to a precise disclosed form. Many modifications and variations are possible taking into account the previous teachings. The preferred embodiment was selected and described in order to better explain the principles of the invention and its practical application. The above description is intended to enable other experts in the art to better employ the invention in various embodiments and with various modifications suitable for the particular use contemplated. The scope of the invention is to define through the following claims.

Claims (19)

1. CLAIMS An upstream converter for converting an IF television signal into a VHF or UHF signal, said upstream converter processes digital or analog television signals, said upstream converter comprising: an upconversion circuit for receiving an input television signal and for sending a converted television signal; and a reference signal circuit for supplying a reference signal to a modulator, external relative to said rising converter, which is generating said IF signal; wherein said reference signal circuit generates a first reference signal if said input television signal is an analog signal and generates a second reference signal, different from said first reference signal, if said input television signal is a digital signal The upconverter according to claim 1, wherein said reference signal circuit comprises a voltage controlled oscillator with an output range including both said first reference signal and said second reference signal. The upconverter according to claim 2, wherein said reference signal circuit further comprises a loop circuit synchronized in phase to control said oscillator to send said first reference signal or said second reference signal. The upconverter according to claim 3, wherein said reference signal circuit further comprises a control circuit for determining whether said input television signal is a digital or analog signal and for configuring said loop circuit synchronized in phase according to whether said input television signal is a digital signal or an analog signal. The upconverter according to claim 4, wherein said control circuit samples said input television signal to determine whether said input television signal is analog or digital. The upconverter according to claim 4, wherein said control circuit receives a control signal indicating whether said input television signal is a digital or analog signal. The upconverter according to claim 1, wherein said first reference signal has a frequency of 45.75 MHz and said second reference signal has a frequency of 44 MHz. A method for upconverting an IF television signal into a VHF or UHF signal regardless of whether said IF television signal is a digital or analog television signal, said method comprises performing said upconversion and sending a first reference signal if said input television signal is an analog signal and sending a second reference signal if said input television signal is a digital signal. The method according to claim 8, further comprising the selective generation of said first reference signal or said second reference signal with a voltage controlled oscillator. The method according to claim 9, further comprising controlling said oscillator with a loop circuit synchronized in phase. The method according to claim 10, further comprising the determination of whether said input television signal is a digital signal or an analog signal and the configuration of said loop circuit synchronized in phase according to whether said input television signal is a digital signal or an analog signal with a control circuit. . The method according to claim 11, further comprising sampling said input television signal with said control circuit to determine if said input television signal is analog or digital. . The method according to claim 11, further comprising the reception, with said control circuit, of a control signal indicating whether said input television signal is a digital signal or an analog signal. The method according to claim 8, further comprising determining with a control circuit whether said input television signal is a digital signal or an analog signal and selectively providing said first reference signal or said second reference signal in response. The method according to claim 8, further comprising providing said second reference signal to an upconversion circuit as a test signal to test said upconversion circuit. an upstream converter for converting an IF television signal into a VHF or UHF signal, said upstream converter processes digital or 16.Analogical television signals, said upstream converter comprising: an upconversion device for receiving an input television signal and for send a converted television signal; and a reference signal device for supplying a reference signal; wherein said reference signal device sends a first reference signal if said input television signal is an analog signal and generates a second output signal if said input television signal is a digital signal. The upconverter according to claim 16, wherein said reference signal device comprises a voltage controlled oscillation device with an output range that includes both said first reference signal and said second reference signal. The upconverter according to claim 17, wherein said reference signal device further comprises a loop-synchronized loop device for controlling said oscillation device to produce either said first reference signal or said second signal reference. The upconverter according to claim 18, wherein said reference signal device further comprises a control device for determining whether said input television signal is a digital or analog signal and for configuring said synchronized loop device in phase according to whether said television signal is a digital signal or an analog signal. The upconverter according to claim 19, wherein said control device samples said input television signal to determine whether said input television signal is an analog or digital signal. The upconverter according to claim 19, wherein said control device receives a control signal indicating whether said input television signal is a digital signal or an analog signal.