Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N5/00—Details of television systems
  • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
  • H04N5/46—Receiver circuitry for the reception of television signals according to analogue transmission standards for receiving on more than one standard at will
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
  • H04N21/41—Structure of client; Structure of client peripherals
  • H04N21/426—Internal components of the client ; Characteristics thereof
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
  • H04N21/41—Structure of client; Structure of client peripherals
  • H04N21/426—Internal components of the client ; Characteristics thereof
  • H04N21/42607—Internal components of the client ; Characteristics thereof for processing the incoming bitstream
  • H04N21/4263—Internal components of the client ; Characteristics thereof for processing the incoming bitstream involving specific tuning arrangements, e.g. two tuners
  • H04N21/42638—Internal components of the client ; Characteristics thereof for processing the incoming bitstream involving specific tuning arrangements, e.g. two tuners involving a hybrid front-end, e.g. analog and digital tuners
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
  • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
  • H04N21/438—Interfacing the downstream path of the transmission network originating from a server, e.g. retrieving MPEG packets from an IP network
  • H04N21/4382—Demodulation or channel decoding, e.g. QPSK demodulation

Definitions

• the present invention relates to a television signal receiver, and in particular, the present invention relates to a broadband television signal receiver for receiving multi-standard analog television signals, digital television signals and data channels.
• a television or video recorder includes a television signal receiver (or television receiver) to receive terrestrial broadcast, cable television or satellite broadcast television signals and to process the television signals into the appropriate video signals for display or for recording.
• Television signals are transmitted in analog or digital formats and in accordance with a variety of standards.
• NTSC National Television Standards Committee
• PAL Phase Alternate Lines
• SECAM Sequential Couleur Avec Memoire
• television receivers are traditionally made specifically for the analog or digital format and for a specific standard.
• televisions or video recording equipments are dedicated equipments which can only be used in the geographic regions in which the television standard is broadcasted.
• Multi-standard equipments are known. In most instances, multi-standard equipments are built by duplicating the hardware necessary to receive television signals in different formats and in several standards, increasing the complexity and the cost of manu acturing the equipments .
• FIG. 1 is a block diagram of a conventional television receiver.
• the operation of television receiver 10 includes two main components. First, receiver 10 receives the incoming signal and converts the incoming radio frequency (RF) signal to an intermediate frequency (IF) signal. Then, receiver 10 converts the IF signal to the baseband signals.
• the baseband signals are coupled to appropriate video and audio decoders to generate the display signals (e.g. RGB) or sound.
• television receiver 10 includes a tuner 14 for receiving the input RF signal on input terminal 12 and converting the RF signal to an IF signal by one or more frequency conversions.
• the frequency conversions are generally implemented as single or dual super-heterodyne conversions.
• the intermediate frequency is dictated by the geographical area the receivers are to be used. Currently, there are five intermediate frequencies being used in the world. For example, in the United States, the IF is 41 to 47 MHz.
• Television receiver 10 includes a channel filter 18 and a demodulator 20 for converting the IF signal to video and audio baseband signals.
• Channel filter 18 is typically a discrete filter implemented as a SAW (Surface Acoustic Wave) filter.
• the shape of the SAW filter is designed specifically for the format (analog or digital TV) and the television standard (NTSC, PAL or SECAM) of the television signals being received.
• Demodulator 20 is typically a dedicated component and designed specifically for a predetermined television signal format and a predetermined television standard.
• a bank of channel filters 18a to 18c is provided, each of the channel filters designed for a specific format and standard.
• a bank of demodulators 20a to 20c is also provided, each demodulator receiving filtered signals from a corresponding channel filter.
• the demodulator is a VIF/SIF module.
• the VIF/SIF module provides a video output called CVBS (Composite Video Baseband Signal) and audio outputs, such as MPX or A2.
• CVBS Composite Video Baseband Signal
• the demodulator is a digital demodulator typically including a down-converter, an analog-to-digital converter and other supporting circuitry to perform the demodulation.
• the digital demodulator outputs data in a MPEG data stream.
• the conventional multi-standard television receivers have several shortcomings. First, conventional television receivers use discrete analog and digital components. The receivers are typically bigger in size and more costly to manufacture. Second, the conventional multi- standard television receivers require duplicate components to support the different television standards. Consequently, such multi-standard television receivers are large in dimensions and costly to manufacture.
• a television (TV) receiver includes a multi- standard channel filter with a programmable intermediate frequency adapted to receive television signals in a variety of television standards and formats.
• a receiver includes a tuner and a channel filter.
• the tuner receives input RF signals encoding information in one of a number of formats and converts the input RF signals to intermediate signals having an intermediate frequency (IF) .
• the intermediate signals are coupled to the channel filter.
• the channel filter includes an anti-aliasing filter for filtering the intermediate signals, an analog-to-digital converter for sampling the filtered intermediate signals and generating a digital representation thereof, and a signal processor for processing the digital representation of the intermediate signals in accordance with the format of the input RF signal .
• the signal processor generates digital output signals indicative of information encoded in the input RF signal .
• the formats of the input RF signals include analog television signals and digital television signals.
• the receiver further includes a bank of demodulators, each coupled to receive digital output signals from the signal processor. Each of the demodulators operates to demodulate the digital output signals according to one of the formats of the input RF signal and generates the corresponding video and audio baseband signals.
• Figure 1 is a block diagram of a conventional multistandard television receiver.
• Figure 2 is a block diagram of a television receiver according to one embodiment of the present invention.
• Figure 3 is a circuit diagram of an anti-aliasing filter which can be used to construct the anti-aliasing filter of Figure 2.
• Figure 4 is a circuit diagram of an anti-aliasing filter which can be used to construct the anti-aliasing filter of Figure 2.
• Figure 5 is a waveform of a filter function that can be implemented in the DSP of Figure 2 for processing analog television signals.
• a television (TV) receiver includes a multi- standard channel filter with a programmable intermediate frequency adapted to receive television signals in a variety of television standards and formats.
• the channel filter accepts a preselected intermediate frequency regardless of the standards or formats of the television signals.
• the channel filter digitizes the incoming television signals and perform signal processing of the incoming signals in the digital domain.
• the TV receiver of the present invention eliminates the need for analog components, such as SAW filters.
• the TV receiver of the present invention can be readily integrated in one integrated circuit to reduce the size and the manufacturing cost of the receiver.
• the TV receiver of the present invention reconfigures the same circuit modules to support multi-standard reception, obviating the need to provide duplicate components.
• FIG. 2 is a block diagram of a television receiver according to one embodiment of the present invention.
• television receiver 50 receives input RF signals, such as those received on an antenna or on a cable line, on an input terminal 52.
• the input RF signals are coupled to a tuner 54 which operates to convert the input RF signal to an intermediate signal using one or more frequency conversions.
• tuner 54 can perform a single or dual super-heterodyne conversion.
• tuner 54 is a commercially available discrete component and outputs intermediate signals having an intermediate frequency (IF) that is determined by the geographic region of interest.
• IF intermediate frequency
• tuner 54 is an integrated component of receiver 50.
• tuner 54 can be designed to generate intermediate signals having an intermediate frequency of any values.
• the IF used by tuner can be the same as or different than the IF specified by the worldwide standards.
• TV receiver 50 includes a multi-standard channel filter 58, tuner 54 can use the same IF for receiving analog or digital television signals in any standards.
• the value of the IF in an integrated tuner is a matter of design choice.
• the IF is selected to be 20 MHz or higher.
• TV receiver 50 includes multi-standard channel filter 58 for filtering and processing the intermediate signals from tuner 54.
• Multi-standard channel filter 58 includes an anti-aliasing filter 60, an analog-to- digital converter (ADC) 62 and a digital signal processor
• channel filter 58 is capable of receiving intermediate signals from tuner 54 having any intermediate frequency. Furthermore, channel filter 58 digitizes the incoming televisions signals and performs subsequent processing in the digital domain entirely. Thus, by applying the appropriate sampling frequency at the ADC circuit and the appropriate signal processing functions at the DSP circuit, channel filter 58 can handle television signals in any format (analog or digital) and in any standard (NTSC, PAL or ATSC) .
• Anti-aliasing filter 60 performs pre-processing of the intermediate signals from tuner 54 to prevent aliasing from occurring when the intermediate signals are subsequently sampled and digitized by ADC 62.
• anti-aliasing filter 60 can be realized with a SAW filter.
• anti-aliasing filter 60 is implemented as shown in Figure 3 using capacitors and inductors.
• anti-aliasing filter 60 is realized with transconductors (gmC) 99 as shown in Figure 4.
• ADC 62 operates to sample the filtered intermediate signals to generate a digital representation thereof.
• ADC 62 is a 10-bit converter and has a sampling rate of up to 40 megasamples per second.
• the center frequency of anti-aliasing filter 60 and the sampling frequency of ADC 62 are selected based on trie intermediate frequency of the intermediate signal . In one embodiment, both the center frequency of anti-aliasing filter 60 and the sampling frequency of ADC 62 are set to be at least twice the bandwidth of the intermediate frequency signal.
• the center frequency of anti-aliasing filter 60 can be adjusted by varying the voltage Vctrl of transconductors 99.
• the sampling frequency of ADC 62 can be adjusted by using a voltage controlled oscillator and a phase locked loop.
• a tuning control circuit 67 is included for adjusting the center frequency of anti-aliasing filter 60 and the sampling frequency of ADC 62.
• Tuning control circuit 67 can receive a control signal external to TV receiver 50, such as a manual control signal from a user.
• Tuning control circuit 67 can also perform auto-detection of the intermediate frequency of the intermediate signals and adjust the operating frequencies of the anti-aliasing filter and the ADC accordingly.
• DSP 64 processes the digital signals according to the television standard to which the input RF signal is encoded.
• channel filter 58 includes a standard selection circuit 68 for selecting between the several analog television standards and the several digital television standards.
• DSP 64 applies the appropriate filter function, such as an impulse response, to the digital signals depending on the state of standard selection circuit 68.
• the coefficients of the filter functions are stored in a look-up table in a memory 70. DSP 64 retrieves the coefficients from memory 70 to be applied to the incoming digital signals.
• DSP 64 is a programmable and reconfigurable processor.
• DSP 64 implements a finite impulse response (FIR) filter which is reconfigured based on the TV standard selected.
• FIR finite impulse response
• DSP 64 includes two computing units to speed up the computation time. Specifically, the filtering operations of the real and imaginary parts in the frequency domain are carried out in parallel. In other embodiments, DSP 64 may include only one computing unit.
• Standard selection circuit 68 can be implemented in one of many ways. The selection of the correct standard can be made manually by the user of the television system, such as by activating a switch, or the selection can be made automatically by providing an auto-detection capability in TV receiver 50. In the present embodiment, auto-detection is implemented by detecting in the baseband signals the presence or absence of carrier signals which uniquely identify the television standards. For example, analog television signals can be identified by the analog visual carrier signal while digital television signals can be identified by the pilot carrier. Each demodulator in bank 66 generates a signal which is fed back to standard selection circuit 68 indicating which television standard the input signal is encoded. In other embodiments, other means for selecting between the different standards can be used.
• DSP 64 applies a video filter function and a sound filter function to the digitized signals to separate the video signals from the audio signals.
• the video and sound filters can be implemented as FIR filters. An example of such filter function is shown in Figure 5.
• DSP 64 can also implement other filter functions such as ghost cancellation for reducing the interference of the input signal.
• the filter response is then derived from the measured channel response .
• DSP 64 applies a filter function to the digitized signals.
• the filter function can be implemented as a FIR filter.
• An example is the ATSC-VSB standard where the filter response is specified as raised root cosine with 0.114 roll- off (refer to the ATSC A-83 specification) .
• additional filter functions such as an equalizer for echo cancellation (multipath), can also be implemented in DSP 64. The filter response is then derived from the measured channel response.
• the output signals from channel filter 58 are coupled to a bank of demodulators 66 for generating into the appropriate video and audio baseband signals.
• the video and audio baseband signals are usually coupled to video and audio decoders before being displayed or playback on a view screen.
• demodulators 66 include a demodulator for analog television signals 66a, a demodulator for digital television signals 66b and a demodulator 66c for digital data channels.
• Analog demodulator 66a performs demodulation of the analog television signals in the digital domain.
• a digital-to-analog converter (not shown) can be included between the output terminal of DSP 64 and the input terminal of analog demodulator 66a.
• Analog demodulator 66a provides three output signals: a Composite Video Baseband Signal (CVBS) containing the video information, and audio 1 and audio 2 containing the audio information.
• Audio 1 and audio 2 signals can be AM modulated, FM modulated or Intercarrier signals.
• the intercarrier signal is a signal that can contain any format of modulated sound. It is usually connected to an external audio decoder.
• TV receiver 50 can readily interface with other standard components, such as a video and sound decoder, thereby providing compatibility with existing television components.
• An additional digital-to-analog converter may be coupled to the output terminal of demodulator 66a if analog output signals are desired.
• Digital demodulator 66b operates to decode the incoming digital television signal .
• digital television signals are modulated in a VSB, QAM or COFDM scheme.
• Digital demodulator 66b generated an MPEG data stream as output signals, thereby providing compatibility with other existing television components.
• TV receiver 50 is an integrated circuit where tuner 54, channel filter 58 and demodulators 66 are all integrated onto the same piece of integrated circuit. In another embodiment, TV receiver 50 can be manufactured as two or more integrated circuits .
• the television reciever of the present invention can be configured as a broadband receiver for receiving multi-standard analog or digital television signals, and broadcast data channels. Furthermore, the receiver can be configured to receive analog television channels from different television standards. Thus, the television receiver can be readily adaptable for use worldwide for television reception.
• the television receiver of the present invention can be used to receive television signals distributed in any manner and provides excellent reception performance.
• the TV receiver of the present invention can be used for the reception of terrestrial broadcast and cable transmission.
• the television reciever of the present invention eliminates the needs for analog components, such as SAW filters. Therefore, all the circuit modules of the TV receiver, including filtering functions, equalizer, ghost cancellation and video and sound splitter can be integrated onto the same integrated circuit. Increasing the level of component integration has the effect of reducing the size of the receiver and the manufacturing cost thereof.
• the television receiver of the present invention provides interfaces that are compatible with interfaces of existing components. Specifically, the television receiver of the present invention provides video, audio and MPEG output signals that are compatible with analog or digital television standards so that the receiver can be readily adapted into existing television systems.

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• 2004
  • 2004-01-20 WO PCT/US2004/001615 patent/WO2005081519A1/en not_active Application Discontinuation
  • 2004-01-20 CN CNA2004800407370A patent/CN1969543A/zh active Pending
  • 2004-01-20 JP JP2006551014A patent/JP2007519365A/ja active Pending
  • 2004-01-20 EP EP04703714A patent/EP1706994A1/en not_active Withdrawn

Non-Patent Citations (1)

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