US20050020222A1

US20050020222A1 - Apparatuses and methods for tuning a frequency conversion device and processing a signal

Info

Publication number: US20050020222A1
Application number: US10/854,768
Authority: US
Inventors: Richard Nelson; Brian Sprague; Donald McMullin; Richard Prodan; Pieter Vorenkamp
Original assignee: Broadcom Corp
Current assignee: Avago Technologies International Sales Pte Ltd
Priority date: 2003-05-27
Filing date: 2004-05-27
Publication date: 2005-01-27
Also published as: US7233778B2; US20050017882A1

Abstract

An apparatus for tuning a frequency conversion device. The apparatus has a channel identifier, a channel cross-referencer, and a frequency conversion device tuner. The channel identifier is configured to identify a first channel to which a receiver is tuned. The channel cross-referencer is coupled to the channel identifier and is configured to cross-reference the first channel with a second channel. The frequency conversion device tuner is coupled to the channel cross-referencer and is configured to tune the frequency conversion device to the second channel. An apparatus for processing a signal. The apparatus has an input port, a signal format identifier, a switch, a converter, an output port, and a bypass signal path. The input port is configured to receive the signal. The signal format identifier is coupled to the input port and configured to identify the signal as having a first format or a second format. The switch is coupled to the signal format identifier. The converter is configured to be coupled to the switch and to convert the signal from the first format to the second format. The output port is coupled to the converter and configured to produce the signal. The bypass signal path is coupled to the output port and configured to be coupled to the switch and to convey the signal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/473,190, filed May 27, 2003, which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to television systems.
2. Background Art
Improvements in television (TV) technologies over the past half century have facilitated the development of different systems for providing TV signals. In addition to broadcast TV systems, such systems include community antenna TV (CATV) systems (i.e., cable TV) and direct-to-home (DTH) TV systems (i.e., satellite TV). Providers of broadcast and DTH TV signals must contend with the locations and the widths of the bands of frequencies in the electromagnetic spectrum that have been allocated to them by the United States Federal Communications Commission (FCC). Providers of CATV signals, which typically are conveyed via transmission lines, such as coaxial cables, can be limited by the lowpass filter characteristics of the transmission lines. For these reasons, the different systems generally operate over different bands of frequencies.
Because broadcast TV systems were developed before CATV systems or DTH TV systems, a majority of TV receivers currently in use are configured to operate at the bands of frequencies assigned for broadcast TV signals. Providers of CATV signals and DTH TV signals typically furnish their users with frequency conversion devices, such as set-top boxes, so that their TV signals can be presented on these TV receivers. A TV receiver and a frequency conversion device usually are operated independently. For example, the switch that provides power to the TV receiver is different from the switch that provides power to the frequency conversion device. Likewise, each of the TV receiver and the frequency conversion device has its own tuner. Often each of the TV receiver and the frequency conversion device has a corresponding remote control unit. This can cause confusion for the user. Although universal remote control units are available that combine the functions of the TV receiver and the frequency conversion device remote control units, such a remedy entails having the user obtain a third remote control unit.
Furthermore, it is also not uncommon that a broadcast TV channel with a given numerical designator (e.g., channel thirteen) is transmitted by a CATV system or a DTH TV system on a channel with a different numerical designator (e.g., channel nine). Here, the CATV channel or the DTH TV channel is merely a conduit for the broadcast TV channel. This situation can place the user in the position of having to remember two numerical designators for such a channel, particularly when a TV program (e.g., broadcast news) identifies the channel by the numerical designator of the broadcast TV channel. However, even when the broadcast TV channel and the CATV channel or DTH TV channel have the same numerical designator, it is not uncommon that these channels are transmitted within different bands of frequencies. For example, broadcast TV channel nineteen is transmitted at a band of frequencies centered at about 503 MHz while CATV channel nineteen is transmitted at a band of frequencies centered at about 153 MHz. Thus, there is a need for a method whereby a frequency conversion device can be tuned using a TV receiver tuner.
Advancements in TV technologies have also facilitated the development of additional services that can be rendered via TV systems. Such services include, but are not limited to, more channels for TV programs, video on demand, and Internet communications. However, the ability to provide simultaneously several of these services to a user can be constrained by the widths of the bands of frequencies that are available for (e.g., assigned by the FCC) or capable of (e.g., the lowpass filter characteristics of transmission lines) providing TV signals. Because of these frequency constraints, expanding the number of services that TV systems can simultaneously provide depends upon an ability to increase the amount of data that can be transmitted within the given bands of frequencies.
The development of digital formatted TV signals has been instrumental in increasing the amount of data that can be transmitted within the given frequency bands. A digital formatted TV channel consumes less bandwidth than a conventional analog formatted TV channel. Also, digital formatted TV channels can be multiplexed together for transmission. For these reasons, providers of TV signals have pursued a transition to digital formatted TV signals. Unfortunately, digital TV receivers continue to cost significantly more than their analog counterparts. Therefore, the rate of transition to digital TV receivers has lagged the rate of transition to digital formatted TV signals. Thus, there is also a need for a method whereby an analog TV receiver can receive both analog and digital TV signals.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to television (TV) systems. In an embodiment, the present invention comprises an apparatus for tuning a frequency conversion device. The apparatus has a channel identifier, a channel cross-referencer, and a frequency conversion device tuner. The channel identifier is configured to identify a first channel to which a receiver is tuned. The channel cross-referencer is coupled to the channel identifier and is configured to cross-reference the first channel with a second channel. The frequency conversion device tuner is coupled to the channel cross-referencer and is configured to tune the frequency conversion device to the second channel. The first channel is defined by a first signal providing system and the second channel is defined by a second signal providing system.
The channel identifier can identify a carrier frequency of the first channel from a leakage of an electromagnetic energy from a receiver tuner of the receiver. The leakage of the electromagnetic energy can be from a local oscillator of the receiver tuner. The channel identifier can comprise a second receiver, a processor, and an identifier. Optionally, the channel identifier can further comprise a converter. The second receiver can be configured to receive the leakage of the electromagnetic energy. The converter can be coupled to the second receiver and configured to convert the electromagnetic energy to a different format. The processor can be coupled to the second receiver and configured to derive a frequency domain distribution of the electromagnetic energy. The identifier can be coupled to the processor and configured to identify the carrier frequency from the frequency domain distribution.
Alternatively, the channel identifier can identify a carrier frequency of the first channel from an electromagnetic signal transmitted from a remote control unit for the receiver. The channel identifier can comprise a second receiver, a processor, and an identifier. Optionally, the channel identifier can further comprise a converter. The second receiver can be configured to receive the electromagnetic signal. The converter can be coupled to the second receiver and configured to convert the electromagnetic signal to a different format. The processor can be coupled to the second receiver and configured to derive a frequency domain distribution of the electromagnetic signal. The identifier can be coupled to the processor and configured to identify the carrier frequency from the frequency domain distribution.
The channel cross-referencer can comprise a port, a processor, and a memory. The port is coupled to the channel identifier and configured to receive first data that identifies the first channel. The processor is coupled to the port and configured to produce second data that identifies the second channel. The memory is coupled to the processor and configured to store the second data.
In another embodiment, the present invention comprises an apparatus for processing a signal. The apparatus has an input port, a signal format identifier, a switch, a converter, an output port, and a bypass signal path. The input port is configured to receive the signal. The signal format identifier is coupled to the input port and configured to identify the signal as having a first format or a second format. The switch is coupled to the signal format identifier. The converter is coupled to the switch and configured to convert the signal from the first format to the second format. The output port is coupled to the converter and configured to produce the signal. The bypass signal path is coupled between the output port and the switch and configured to convey the signal. The first format is an analog format or a digital format. If the first-format is an analog format, then the second format is a digital format. If the first format is a digital format, then the second format is an analog format.
The signal format identifier can determine if energy within a frequency band of the signal is greater than a threshold energy. The signal format identifier can comprise a filter, a comparer, and a controller. The filter can be configured to isolate the energy within the frequency band. The comparer can be coupled to the filter and configured to compare the energy within the frequency band with the threshold energy. The controller can be coupled to the comparer and configured to position the switch.
Optionally, the apparatus can further comprise a mixer coupled to the output port and configured to convert the signal from being centered at a first frequency to being centered at a second frequency.
Optionally, the apparatus can further comprise a demodulator and an encoder. The demodulator can be coupled to the converter and configured to demodulate the signal. The encoder can be coupled to the converter and configured to encode the signal. The apparatus can also optionally further comprise a mixer. The mixer can be coupled to the demodulator and configured to convert the signal from being centered at a first frequency to being centered at a second frequency. The apparatus can also optionally further comprise a demultiplexer and a filter. The demultiplexer can be coupled to the demodulator and configured to demultiplex the signal to a first channel and to a second channel. The filter can be coupled to the encoder and configured to isolate the first channel from the second channel. The apparatus can also optionally further comprise a combiner. The combiner can be coupled to the encoder and configured to combine the first channel with the second channel.
In yet another embodiment, the present invention comprises a method for tuning a frequency conversion device. A first channel to which a receiver is tuned is identified. The first channel is cross-referenced with a second channel. The frequency conversion device is tuned to the second channel. The first channel is defined by a first signal providing system and the second channel is defined by a second signal providing system.
To identify the first channel, a carrier frequency of the first channel to which the receiver is tuned can be identified from a leakage of electromagnetic energy from a receiver tuner of the receiver. The electromagnetic energy can be at a radio frequency. To identify the carrier frequency, the leakage of the electromagnetic energy can be received. Optionally, the electromagnetic energy can be converted to a digital format. A frequency domain distribution of the electromagnetic energy can be derived. The carrier frequency can be identified from the frequency domain distribution.
Alternatively, to identify the first channel, a carrier frequency of the first channel to which the receiver is tuned can be identified from an electromagnetic signal transmitted from a remote control unit for the receiver. The electromagnetic signal can be at an infrared frequency, a radio frequency, or other frequency. To identify the carrier frequency, the electromagnetic signal can be received. Optionally, the electromagnetic signal can be converted to a digital format. A frequency domain distribution of the electromagnetic signal can be derived. The carrier frequency can be identified from the frequency domain distribution. To cross-reference the first channel with the second channel, first data that identifies the first channel can be received. The first data can be cross-referenced with second data that identifies the second channel. The second data can be produced.
In still another embodiment, the present invention comprises a method for processing a signal. The signal is identified as having a first format or a second format. The first format is an analog format or a digital format. If the first format is an analog format, then the second format is a digital format. If the first format is a digital format, then the second format is an analog format. The signal can be a radio frequency signal. If the signal has the first format, then the signal is converted from the first format to the second format. Preferably, if the signal has the second format, then the signal is conveyed. Optionally, the signal can be converted from being centered at a first frequency to being centered at a second frequency.
To identify the format of the signal, energy within a frequency band of the signal can be determined to be greater than a threshold energy. The frequency band can be within a channel of the signal. To determine if the energy within the frequency band is greater than the threshold energy, the energy within the frequency band can be isolated and compared with the threshold energy.
Optionally, if the signal has the first format, then the signal can be converted from being centered at a first frequency to being centered at a second frequency, demodulated, encoded, or any combination of the foregoing. Optionally, if the signal has a first channel multiplexed with a second channel, then the signal can be demultiplexed to the first channel and to the second channel. Optionally, if the signal has a first channel and a second channel, then the first channel can be combined with the second channel. Optionally, if the signal has a first channel and a second channel, then the first channel can be isolated from the second channel.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.
FIG. 1 is a block diagram of an embodiment of a frequency conversion device tuning apparatus 100 of the present invention.
FIG. 2 is a block diagram of an embodiment of channel identifier 102.
FIG. 3 is a block diagram of an alternative embodiment of channel identifier 102.
FIG. 4 is a block diagram of an embodiment of channel cross-referencer 104.
FIG. 5A is a block diagram of an embodiment of a signal processing apparatus 500 of the present invention.
FIGS. 5B and 5C are graphs of first format 516 and second format 518.
FIG. 5D is a graph of energy 520 within frequency band 522.
FIG. 6A is a block diagram of an embodiment of a signal processing apparatus 600 of the present invention.
FIGS. 6B-6E are graphs of signal 514 as a function of frequency.
FIG. 7A is a block diagram of an embodiment of a signal processing apparatus 700 of the present invention.
FIGS. 7B-71 are graphs of signal 514 as a function of frequency.
FIG. 8 shows a flow chart of a method 800 for tuning a frequency conversion device in the manner of the present invention.
FIG. 9 shows a flow chart of a method 802 a for identifying a first channel to which a receiver is tuned.
FIG. 10 shows a flow chart of a method 802 b for identifying a first channel to which a receiver is tuned.
FIG. 11 shows a flow chart of a method 804 for cross-referencing the first channel with a second channel.
FIG. 12 shows a flow chart of a method 1200 for processing a signal in the manner of the present invention.
FIG. 13 shows a flow chart of a method 1202 for identifying the signal channel as having a first format or a second format.
The preferred embodiments of the invention are described with reference to the figures where like reference numbers indicate identical or functionally similar elements. Also in the figures, the left most digit of each reference number identifies the figure in which the reference number is first used.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to television (TV) systems. Because broadcast TV systems were developed before community antenna TV (CATV) systems or direct-to-home (DTH) TV systems, a majority of TV receivers currently in use are configured to operate at the bands of frequencies assigned for broadcast TV signals. Providers of CATV signals and DTH TV signals typically furnish their users with frequency conversion devices, such as set-top boxes, so that their TV signals can be presented on these TV receivers. A TV receiver and a frequency conversion device usually are operated independently. For example, the switch that provides power to the TV receiver is different from the switch that provides power to the frequency conversion device. Likewise, each of the TV receiver and the frequency conversion device has its own tuner.
It is also not uncommon that a broadcast TV channel with a given numerical designator (e.g., channel thirteen) is transmitted by a CATV system or a DTH TV system on a channel with a different numerical designator (e.g., channel nine). Here, the CATV channel or the DTH TV channel is merely a conduit for the broadcast TV channel. This situation can place the user in the position of having to remember two numerical designators for such a channel, particularly when a TV program (e.g., broadcast news) identifies the channel by the numerical designator of the broadcast TV channel. However, even when the broadcast TV channel and the CATV channel or DTH TV channel have the same numerical designator, it is not uncommon that these channels are transmitted within different bands of frequencies. For example, broadcast TV channel nineteen is transmitted at a band of frequencies centered at about 503 MHz while CATV channel nineteen is transmitted at a band of frequencies centered at about 153 MHz. The present invention is directed towards an apparatus and a method for tuning a frequency conversion device using a TV receiver tuner.
Furthermore, the ability to provide simultaneously several services to a user via a TV system can be constrained by the widths of the bands of frequencies that are available for (e.g., assigned by the Federal Communications Commission) or capable of (e.g., the lowpass filter characteristics of transmission lines) providing TV signals. Because of these frequency constraints, expanding the number of services that TV systems can simultaneously provide depends upon an ability to increase the amount of data that can be transmitted within the given bands of frequencies. For this reason, providers of TV signals have pursued a transition to digital formatted TV signals.
Unfortunately, digital TV receivers continue to cost significantly more than their analog counterparts. Therefore, the rate of transition to digital TV receivers has lagged the rate of transition to digital formatted TV signals. Accordingly, the present invention is also directed towards an apparatus and a method for receiving both analog and digital TV signals at an analog TV receiver.
FIG. 1 is a block diagram of an embodiment of a frequency conversion device tuning apparatus 100 of the present invention. Apparatus 100 comprises a channel identifier 102, a channel cross-referencer 104, and a frequency conversion device tuner 106. Channel identifier 102 is configured to identify a first channel 108 to which a receiver 110 is tuned. First channel 108 is defined by a first signal providing system 112. For example, first signal providing system 112 can be, but is not limited to, a broadcast TV system. For example, receiver 110 can be, but is not limited to, a TV receiver. Channel cross-referencer 104 is coupled to channel identifier 102 and is configured to cross-reference first channel 108 with a second channel 114. Second channel 114 is defined by a second signal providing system 116. For example, second signal providing system 116 can be, but is not limited to, a CATV system or a DTH TV system. Frequency conversion device tuner 106 is coupled to channel cross-referencer 104 and is configured to tune a frequency conversion device 118 to second channel 114. For example, frequency conversion device 118 can be a set-top box.
If first channel 108 of first signal providing system 110 has a given numerical designator (e.g., channel thirteen) is transmitted by second signal providing system 116 on second channel 114, which has a different numerical designator (e.g., channel nine), then apparatus 100 can tune frequency conversion device 118 using the tuner of receiver 110 so that first channel 108 is identified by its given numerical designator (e.g., channel thirteen) even though second channel 114 (e.g., channel nine) is transmitted to receiver 110. Likewise, if first channel 108 and second channel 114 have the same numerical designator (e.g., channel nineteen) but are transmitted within different bands of frequencies (e.g., bands of frequencies centered, respectively, at about 503 MHz and about 153 MHz), then apparatus 100 can tune frequency conversion device 118 using the tuner of receiver 110 so that frequency conversion device 118 converts first channel 108 to the band of frequencies for second channel 114.
FIG. 2 is a block diagram of an embodiment of channel identifier 102. Channel identifier 102 can identify a carrier frequency 202 of first channel 108 from a leakage of an electromagnetic energy 204 from a receiver tuner 206 of receiver 110. Leakage of the electromagnetic energy 204 can be, but is not necessarily, from a local oscillator 208 of receiver tuner 206. Channel identifier 102 can comprise a second receiver 210, a processor 212, and an identifier 214. Optionally, channel identifier 102 can further comprise a converter 216. Second receiver 210 can be configured to receive leakage of the electromagnetic energy 204. Converter 216 can be coupled to second receiver 210 and configured to convert the electromagnetic energy to a different format. For example, if the electromagnetic energy has an analog format, then converter 216 can convert the electromagnetic energy to a digital format. Processor 212 can be coupled to second receiver 210 and configured to derive a frequency domain distribution 218 of the electromagnetic energy. For example, frequency domain distribution 218 can be derived as a Fast Fourier Transform of the digital formatted leakage of the electromagnetic energy 204. Identifier 214 can be coupled to processor 212 and configured to identify carrier frequency 202 from frequency domain distribution 218. For example, the electromagnetic energy at carrier frequency 202 can be greater than the electromagnetic energy at other frequencies within frequency domain distribution 218. Processor 212, identifier 214, or both can be realized using hardware, software, firmware, or any combination of the foregoing.
FIG. 3 is a block diagram of an alternative embodiment of channel identifier 102. Channel identifier 102 can identify carrier frequency 202 of first channel 108 from an electromagnetic signal 302 transmitted from a remote control unit 304 for receiver 110. Channel identifier 102 can comprise a second receiver 306, processor 212, and identifier 214. Optionally, channel identifier 102 can further comprise converter 216. Second receiver 306 can be configured to receive electromagnetic signal 302. Converter 216 can be coupled to second receiver 306 and configured to convert electromagnetic signal 302 to a different format. For example, if electromagnetic signal 302 has an analog format, then converter 216 can convert electromagnetic signal 302 to a digital format. Processor 212 can be coupled to second receiver 306 and configured to derive frequency domain distribution 218 of electromagnetic signal 302. For example, frequency domain distribution 218 can be derived as a Fast Fourier Transform of the digital formatted electromagnetic signal 302. Identifier 214 can be coupled to processor 212 and configured to identify carrier frequency 202 from frequency domain distribution 218. For example, the electromagnetic energy at carrier frequency 202 can be greater than the electromagnetic energy at other frequencies within frequency domain distribution 218. Processor 212, identifier 214, or both can be realized using hardware, software, firmware, or any combination of the foregoing.
The skilled artisan recognizes alternative embodiments for channel identifier 102. Accordingly, the present invention is not limited to the configurations of channel identifier 102 as depicted at FIGS. 2 and 3.
FIG. 4 is a block diagram of an embodiment of channel cross-referencer 104. Channel cross-referencer 104 can comprise a port 402, a processor 404, and a memory 406. Port 402 is coupled to channel identifier 102 and configured to receive first data 408 that identifies first channel 108. Processor 404 is coupled to port 402 and configured to produce second data 410 that identifies second channel 114. Memory 406 is coupled to processor 404 and configured to store second data 410. For example, in addition to identifying first channel 108, first data 408 can also identify an address 412 in memory 406 at which second data 410 is stored. Processor 404 can receive first data 408 from port 402. Processor 404 can access, in memory 406, address 412 identified by first data 408 and produce second data 410. Therefore, second channel 114 is transmitted to receiver 110 even though it is tuned to first channel 108. Processor 404 can be realized using hardware, software, firmware, or any combination of the foregoing. The skilled artisan recognizes alternative embodiments for channel cross-referencer 104. Accordingly, the present invention is not limited to the configuration of channel cross-referencer 104 as depicted at FIG. 4.
FIG. 5A is a block diagram of an embodiment of a signal processing apparatus 500 of the present invention. Apparatus 500 comprises an input port 502, a signal format identifier 504, a switch 506, a converter 508, an output port 510, and a bypass signal path 512. Input port 502 is configured to receive a signal 514. Signal format identifier 504 is coupled to input port 502 and configured to identify signal 514 as having a first format 516 or a second format 518. First format 516 is an analog format or a digital format. If first format 516 is an analog format, then second format 518 is a digital format (FIG. 5B). If first format 516 is a digital format, then second format 518 is an analog format (FIG. 5C). Switch 506 is coupled to signal format identifier 504. Converter 508 is coupled to switch 506 and configured to convert signal 514 from first format 516 to second format 518. Output port 510 is coupled to converter 508 and configured to produce signal 514. Bypass signal path 512 is coupled between output port 510 and switch 506 and configured to convey signal 514.
Signal format identifier 504 can determine if an energy 520 within a frequency band 522 of signal 514 is greater than a threshold energy 524 (FIG. 5D). Signal format identifier 504 can comprise a filter 526, a comparer 528, and a controller 530. Filter 526 can be configured to isolate energy 520 within frequency band 522. Comparer 528 can be coupled to filter 526 and configured to compare energy 520 within frequency band 522 with threshold energy 524. Controller 530 can be coupled to comparer 528 and configured to position switch 506. Filter 526, comparer 528, controller 530, or any combination of the foregoing can be realized using hardware, software, firmware, or any combination of the foregoing. Furthermore, controller 530 can be realized using an electromechanical device or a microelectromechanical device.
For example, the National Television System Committee (NTSC) has established a technical standard for a broadcast TV channel for a TV signal having a conventional analog format. According to the NTSC technical standard, the carrier frequency for the video signal is 1.75 MHz less than the central frequency of the TV channel and the carrier frequency for the audio signal is 2.75 MHz greater than the central frequency of the TV channel. Most of energy 520 for a TV channel having a conventional analog format according to the NTSC technical standard is at frequencies near to the carrier frequency for the video signal and at frequencies near to the carrier frequency for the audio signal. For a TV channel having a conventional analog format according to the NTSC technical standard, little of energy 520 is at the central frequency of the TV channel. In contrast, for a TV channel having a digital format, a substantial portion of energy 520 is at the central frequency of the TV channel.
Threshold energy 524 can be set so that if frequency band 522 has a width that is less than about 3.5 MHz and is located near the central frequency of the TV channel, then energy 520 isolated by filter 526 is: (1) less than threshold energy 524 if the TV channel has a conventional analog format according to the NTSC technical standard and (2) greater than threshold energy 524 if the TV channel has a digital format. In this manner, the format of the TV signal can be identified as analog or digital. Preferably, filter 526 is tunable and configured so that it can be adjusted in conjunction with tuning frequency conversion device 118. Frequency band 522 is not limited to the frequencies recited herein.
If the TV channel has an analog format, then controller 530 positions switch 506 so that it couples input port 502 to output port 510 via signal format bypass signal path 512. If the TV channel has a digital format, then controller 530 positions switch 506 so that it couples input port 502 to output port 510 via converter 508. Apparatus 500 can also be conversely configured so that converter 508 is an analog-to-digital converter and controller 530 positions switch 506 so that it couples input port 502 to output port 510 via bypass signal path 512 if the TV channel has a digital format, but couples input port 502 to output port 510 via converter 508 if the TV channel has an analog format. Switch 506 can be realized by any of a variety of means including, but not limited to a conventional switch, a relay, a transistor, and a microelectromechanical device.
The skilled artisan recognizes alternative embodiments for signal format identifier 504. Accordingly, the present invention is not limited to the configuration of signal format identifier 504 as depicted at FIG. 5.
FIG. 6A is a block diagram of an embodiment of a signal processing apparatus 600 of the present invention. Apparatus 600 comprises input port 502, signal format identifier 504, switch 506, converter 508, output port 510, and bypass signal path 512. Apparatus 600 can further comprise any of a first mixer 602, a demodulator 604, an encoder 606, and a second mixer 608. Described below is an embodiment of apparatus 600 that comprises all of these elements. However, the skilled artisan recognizes alternative embodiments that incorporate some, but not all, of these elements. Accordingly, the present invention is not limited to the configuration of apparatus 600 as depicted at FIG. 6.
Input port 502 is configured to receive signal 514. Signal format identifier 504 is coupled to input port 502 and configured to identify signal 514 as having first format 516 or second format 518. First format 516 is a digital format or an analog format. If first format 516 is a digital format, then second format 518 is an analog format. If first format 516 is an analog format, then second format 518 is a digital format. Switch 506 is coupled to signal format identifier 504. First mixer 602 is configured to be coupled to switch 506 and to convert signal 514 from being centered at a first frequency 610 (FIG. 6B) to being centered at a second frequency 612 (FIG. 6C). For example, first frequency 610 can be a radio frequency and second frequency 612 can be a baseband frequency to facilitate format conversion. Preferably, first mixer 602 is tunable and configured so that first frequency 610 can be adjusted in conjunction with tuning frequency conversion device 118.
Demodulator 604 is coupled to first mixer 602 and configured to demodulate signal 514. If first format 516 is a digital format, then preferably such demodulation is quadrature amplitude demodulation. The skilled artisan is familiar with implementing quadrature amplitude demodulation. Encoder 606 is coupled to demodulator 604 and configured to encode signal 514. Encoder 606 can comprise a video encoder (not shown), an audio encoder (not shown) (e.g., an encoder that complies with a Broadcast Television System Committee stereo encoding standard), and a combiner (not shown) to combine the results of the video encoder and the audio encoder. The skilled artisan is familiar with implementing such an encoding scheme.
Converter 508 is coupled to encoder 606 and configured to convert signal 514 from first format 516 to second format 518. Bypass signal path 512 is configured to be coupled to switch 506 and to convey signal 514. Second mixer 608 is coupled to converter 508 and bypass signal path 512 and configured to convert signal 514 from being centered at a third frequency 614 (FIG. 6D) to being centered at a fourth frequency 616 (FIG. 6E). Preferably, second mixer 608 is tunable and configured so that fourth frequency 616 can be adjusted in conjunction with tuning frequency conversion device 118. Output port 510 is coupled to second mixer 608 and configured to produce signal 514.
For example, if signal 514 received at input port 502 has a digital format, then third frequency 614 can be a baseband frequency and fourth frequency 616 can be a radio frequency. In another example, if signal 514 received at input port 502 has an analog format, then third frequency 614 can be a first radio frequency and fourth frequency 616 can be a second radio frequency. For instance, if signal 514 received at input port 502 is second channel 114 (e.g., channel nineteen) provided by second signal providing system 116 (e.g., CATV), but receiver 110 is configured to operate at the bands of frequencies assigned for first signal providing system 112 (e.g., broadcast TV), then second mixer 608 can be configured to convert second channel 114 centered at third frequency 614 (e.g., about 153 MHz) to first channel 108 (e.g., channel nineteen) centered at fourth frequency 616 (e.g., about 503 MHz).
FIG. 7A is a block diagram of an embodiment of a signal processing apparatus 700 of the present invention. Apparatus 700 comprises input port 502, signal format identifier 504, switch 506, converter 508, output port 510, and bypass signal path 512. Apparatus 700 can further comprise any of first mixer 602, demodulator 604, a demultiplexer 702, encoder 606, an encoder 704, a combiner 706, a filter 708, and second mixer 608. Described below is an embodiment of apparatus 700 that comprises all of these elements. However, the skilled artisan recognizes alternative embodiments that incorporate some, but not all, of these elements. Accordingly, the present invention is not limited to the configuration of apparatus 700 as depicted at FIG. 7.
Input port 502 is configured to receive signal 514. Signal format identifier 504 is coupled to input port 502 and configured to identify signal 514 as having first format 516 or second format 518. If signal 514 has first format 516, then signal 514 has a first channel 710 a multiplexed with a second channel 710 b. First format 516 is a digital format or an analog format. If first format 516 is a digital format, then second format 518 is an analog format. If first format 516 is an analog format, then second format 518 is a digital format. Switch 506 is coupled to signal format identifier 504. First mixer 602 is configured to be coupled to switch 506. First mixer 602 is configured to convert first channel 710 a from being centered at a fifth frequency 712 to being centered at an sixth frequency 714 and to convert second channel 710 b from being centered at a seventh frequency 716 to being centered at an eighth frequency 718 (FIGS. 7B and 7C). For example, fifth frequency 712 and seventh frequency 716 can be radio frequencies and sixth frequency 714 and eighth frequency 718 can be baseband frequencies to facilitate format conversion.
Demodulator 604 is coupled to first mixer 602 and configured to demodulate signal 514. If first format 516 is a digital format, then preferably such demodulation is quadrature amplitude demodulation. The skilled artisan is familiar with implementing quadrature amplitude demodulation. Demultiplexer 702 is coupled to demodulator 604 and configured to demultiplex signal 514 to first channel 710 a (FIG. 7D) and to second channel 710 b (FIG. 7E). Encoders 606 and 704 are coupled to demultiplexer 702. Encoder 606 is configured to encode first channel 710 a; encoder 704 is configured to encode second channel 710 b. Combiner 706 is coupled to encoders 606 and 704 and configured to combine first channel 710 a with second channel 710 b. Filter 708 is coupled to combiner 706 and configured to isolate first channel 710 a or second channel 710 b. Preferably, filter 708 is tunable and configured so that it can be adjusted in conjunction with tuning frequency conversion device 118. For example, if first channel 710 a is centered at sixth frequency 714 and second channel 710 b is centered at eighth frequency 718 (FIG. 7F), then filter 708 can be tuned to sixth frequency 714 to pass first channel 710 a and to block second channel 710 b (FIG. 7G), or filter 708 can be tuned to eighth frequency 718 to pass second channel 710 b and to block first channel 710 a.
Converter 508 is coupled to filter 708 and configured to convert signal 514 (i.e., first channel 710 a or second channel 710 b) from first format 516 to second format 518. Bypass signal path 512 is configured to be coupled to switch 506 and to convey signal 514. Second mixer 608 is coupled to converter 508 and bypass signal path 512 and configured to convert signal 514 from being centered at a ninth frequency 720 (FIG. 7H) to being centered at a tenth frequency 722 (FIG. 71). Preferably, second mixer 608 is configured so that tenth frequency 722 can be adjusted in conjunction with tuning frequency conversion device 118. Output port 510 is coupled to second mixer 608 and configured to produce signal 514.
The format conversion function of converter 508 can be performed before or after the channel isolation function of filter 708. Furthermore, if apparatus 500 included a converter for each channel, then the conversion function of these converters can be performed before the combination function of combiner 706.
FIG. 8 shows a flow chart of a method 800 for tuning a frequency conversion device in the manner of the present invention. In method 800, at a step 802, a first channel to which a receiver is tuned is identified. The first channel is defined by a first signal providing system. For example, the receiver can be a TV receiver. For example, the first channel can be channel nineteen as defined by a broadcast TV system (e.g., transmitted at a band of frequencies centered at about 503 MHz). At a step 804, the first channel is cross-referenced with a second channel. The second channel is defined by a second signal providing system. For example, the second channel can be channel nineteen as defined by a CATV system (e.g., transmitted at a band of frequencies centered at about 153 MHz). At a step 806, the frequency conversion device is tuned to the second channel. For example, the frequency conversion device can be a set-top box.
The first channel can be identified by identifying a carrier frequency of the first channel from a leakage of an electromagnetic energy from a receiver tuner of the receiver. For example, the electromagnetic energy can be at a radio frequency. FIG. 9 shows a flow chart of a method 802 a for identifying a first channel to which a receiver is tuned. In method 802 a, at a step 902, the leakage of the electromagnetic energy is received. For example, leakage of the electromagnetic energy can be, but is not necessarily, from a local oscillator of a receiver tuner. Optionally, at a step 904, the electromagnetic energy can be converted to a digital format. At a step 906, a frequency domain distribution of the electromagnetic energy can be derived. For example, the frequency domain distribution can be derived as a Fast Fourier Transform of the digital formatted leakage of the electromagnetic energy. At a step 908, the carrier frequency can be identified from the frequency domain distribution. For example, the electromagnetic energy at the carrier frequency can be greater than the electromagnetic energy at other frequencies within frequency domain distribution.
The first channel can be identified by identifying a carrier frequency of the first channel from an electromagnetic signal from a remote control unit for the receiver. For example, the electromagnetic signal can be at an infrared frequency, a radio frequency, or other frequency. FIG. 10 shows a flow chart of a method 802 b for identifying a first channel to which a receiver is tuned. In method 802 b, at a step 1002, the electromagnetic signal is received. Optionally, at a step 1004, the electromagnetic signal can be converted to a digital format. At a step 1006, a frequency domain distribution of the electromagnetic signal can be derived. For example, the frequency domain distribution can be derived as a Fast Fourier Transform of the digital formatted electromagnetic signal. At a step 1008, the carrier frequency can be identified from the frequency domain distribution. For example, the electromagnetic energy at the carrier frequency can be greater than the electromagnetic energy at other frequencies within frequency domain distribution.
The skilled artisan recognizes alternative methods for identifying a first channel to which a receiver is tuned. Accordingly, the present invention is not limited to the methods depicted at FIGS. 9 and 10.
FIG. 11 shows a flow chart of a method 804 for cross-referencing the first channel with a second channel. In method 804, at a step 1102, first data that identifies the first channel is received. At a step 1104, the first data is cross-referenced with second data that identifies the second channel that corresponds to the first channel. At a step 1106, the second data is produced. For example, in addition to identifying the first channel, the first data can also identify an address in a memory at which the second data is stored. A processor can receive the first data, access in memory the address identified by the first data, and produce the second data. The skilled artisan recognizes alternative methods for cross-referencing the first channel with a second channel. Accordingly, the present invention is not limited to the method as depicted at FIG. 11.
FIG. 12 shows a flow chart of a method 1200 for processing a signal in the manner of the present invention. Described below is an embodiment of method 1200 that includes several optional steps. However, the skilled artisan recognizes alternative embodiments that incorporate some, but not all, of these several optional steps. Accordingly, method 1200 is not limited to the configuration that includes each of these several optional steps as depicted at FIG. 12.
In method 1200, at a step 1202, the signal is identified as having a first format or a second format. The first format is an analog format or a digital format. If the first format is an analog format, then the second format is an digital format. If the first format is a digital format, then the second format is an analog format. The signal can be a radio frequency signal. At a step 1216, if the signal has the first format, then the signal is converted from the first format to the second format. Preferably, at a step 1218, if the signal has the second format, then the signal is conveyed. Optionally, at a step 1220, the signal can be converted from being centered at a first frequency to being centered at a second frequency. For example, if the signal has a digital format, then the first frequency can be a baseband frequency (see below) and the second frequency can be a radio frequency. In another example, if the signal has an analog format, then the first frequency can be a first radio frequency and the second frequency can be a second radio frequency. For instance, if the signal is TV channel nineteen, then the first frequency can be about 153 MHz (e.g., CATV channel nineteen) and the second frequency can be about 503 MHz (e.g., broadcast TV channel nineteen).
If the signal has the first format, then several optional steps can be performed in addition to the signal being converted from the first format to the second format at step 1216. If the signal has the first format, then optionally, at a step 1204, the signal can be converted from being centered at a third frequency to being centered at a fourth frequency. For example, the third frequency can be a radio frequency and the fourth frequency can be a baseband frequency to facilitate format conversion. If the signal has the first format, then optionally, at a step 1206, the signal can be demodulated. If the first format is a digital format, then preferably such demodulation is quadrature amplitude demodulation. The skilled artisan is familiar with implementing quadrature amplitude demodulation.
If the signal has a first channel multiplexed with a second channel, then optionally, at a step 1208, the signal can be demultiplexed to the first channel and to the second channel. If the signal has the first format, then optionally, at a step 1210, the signal can be encoded. Such encoding can comprise video encoding and audio encoding. The skilled artisan is familiar with implementing such an encoding scheme. If the signal has a first channel and a second channel, then each channel can be encoded. If the signal has a first channel and a second channel, then optionally, at a step 1212, the first channel can be combined with the second channel. If the signal has a first channel and a second channel, then optionally, at a step 1214, the first channel can be isolated from the second channel. For example, if the first channel is centered at a fifth frequency and the second channel is centered at a sixth frequency, then a filter can be used to pass the first channel and to block the second channel.
The signal can be identified as having the first format or the second format by determining if an energy within a frequency band of the signal is greater than a threshold energy. The frequency band can be within a channel of the signal. FIG. 13 shows a flow chart of a method 1202 for identifying the signal channel as having a first format or a second format. In method 1202, at a step 1302, the energy within the frequency band is isolated. At a step 1304, the energy within the frequency band is compared with the threshold energy.
For example, the NTSC has established a technical standard for a broadcast TV channel for a TV signal having a conventional analog format. According to the NTSC technical standard, the carrier frequency for the video signal is 1.75 MHz less than the central frequency of the TV channel and the carrier frequency for the audio signal is 2.75 MHz greater than the central frequency of the TV channel. Most of the energy for a TV channel having a conventional analog format according to the NTSC technical standard is at frequencies near to the carrier frequency for the video signal and at frequencies near to the carrier frequency for the audio signal. For a TV channel having a conventional analog format according to the NTSC technical standard, little of the energy is at the central frequency of the TV channel. In contrast, for a TV channel having a digital format, a substantial portion of the energy is at the central frequency of the TV channel.
The threshold energy can be set so that if the frequency band has a width that is less than about 3.5 MHz and is located near the central frequency of the TV channel, then the isolated energy is: (1) less than the threshold energy if the TV channel has a conventional analog format according to the NTSC technical standard and (2) greater than the threshold energy if the TV channel has a digital format. In this manner, the format of the TV signal can be identified as analog or digital.
The skilled artisan recognizes alternative methods for identifying the signal as having a first format or a second format. Accordingly, the present invention is not limited to the method as depicted at FIG. 13.
Conclusion
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. An apparatus for tuning a frequency conversion device, comprising:

a channel identifier configured to identify a first channel to which a receiver is tuned;

a channel cross-referencer coupled to said channel identifier and configured to cross-reference said first channel with a second channel; and

a frequency conversion device tuner coupled to said channel cross-referencer and configured to tune the frequency conversion device to said second channel;

wherein said first channel is defined by a first signal providing system and said second channel is defined by a second signal providing system.

2. The apparatus of claim 1, wherein said channel identifier identifies a carrier frequency of said first channel from a leakage of an electromagnetic energy from a receiver tuner of said receiver.

3. The apparatus of claim 2, wherein said leakage of said electromagnetic energy is from a local oscillator of said receiver tuner.

4. The apparatus of claim 2, wherein said channel identifier comprises:

a second receiver configured to receive said leakage of said electromagnetic energy;

a processor coupled to said second receiver and configured to derive a frequency domain distribution of said electromagnetic energy; and

an identifier coupled to said processor and configured to identify said carrier frequency from said frequency domain distribution.

5. The apparatus of claim 4, wherein said channel identifier further comprises:

a converter coupled to said second receiver and configured to convert said electromagnetic energy to a different format.

6. The apparatus of claim 1, wherein said channel identifier identifies a carrier frequency of said first channel from an electromagnetic signal transmitted from a remote control unit for said receiver.

7. The apparatus of claim 6, wherein said channel identifier comprises:

a second receiver configured to receive said electromagnetic signal;

a processor coupled to said second receiver and configured to derive a frequency domain distribution of said electromagnetic signal; and

8. The apparatus of claim 7, wherein said channel identifier further comprises:

a converter coupled to said second receiver and configured to convert said electromagnetic signal to a different format.

9. The apparatus of claim 1, wherein said channel cross-referencer comprises:

a port coupled to said channel identifier and configured to receive first data that identifies said first channel;

a processor coupled to said port and configured to produce second data that identifies said second channel; and

a memory coupled to said processor and configured to store said second data.

10. An apparatus for processing a signal, comprising:

an input port configured to receive the signal;

a signal format identifier coupled to said input port and configured to identify the signal as having one of a first format and a second format;

a switch coupled to said signal format identifier;

a converter coupled to said switch and configured to convert the signal from said first format to said second format;

an output port coupled to said converter and configured to produce the signal; and

a bypass signal path coupled between said output port and said switch and configured to convey the signal;

wherein said first format is one of an analog format and a digital format and said second format is one of said analog format and said digital format, but different from said first format.

11. The apparatus of claim 10, further comprising:

a mixer coupled to said output port and configured to convert the signal from being centered at a first frequency to being centered at a second frequency.

12. The apparatus of claim 10, further comprising:

a demodulator coupled to said converter and configured to demodulate the signal; and

an encoder coupled to said demodulator and configured to encode the signal.

13. The apparatus of claim 12, further comprising:

a mixer coupled to said demodulator and configured to convert the signal from being centered at a first frequency to being centered at a second frequency.

14. The apparatus of claim 12, further comprising:

a demultiplexer coupled to said demodulator and configured to demultiplex the signal to a first channel and to a second channel; and

a filter coupled to said encoder and configured to isolate said first channel from said second channel.

15. The apparatus of claim 14, further comprising:

a combiner coupled to said encoder and configured to combine said first channel with said second channel.

16. The apparatus of claim 10, wherein said signal format identifier determines if an energy within a frequency band of the signal is greater than a threshold energy.

17. The apparatus of claim 16, wherein said signal format identifier comprises:

a filter configured to isolate said energy within said frequency band;

a comparer coupled to said filter and configured to compare said energy within said frequency band with said threshold energy; and

a controller coupled to said comparer and configured to position said switch.

18. A method for tuning a frequency conversion device, comprising the steps of:

(1) identifying a first channel to which a receiver is tuned;

(2) cross-referencing the first channel with a second channel; and

(3) tuning the frequency conversion device to the second channel;

wherein the first channel is defined by a first signal providing system and the second channel is defined by a second signal providing system.

19. The method of claim 18, wherein said identifying the first channel step comprises the step of:

(1) identifying a carrier frequency of the first channel to which the receiver is tuned from a leakage of an electromagnetic energy from a receiver tuner of the receiver.

20. The method of claim 19, wherein the electromagnetic energy is at a radio frequency.

21. The method of claim 19, wherein said identifying the carrier frequency step comprises the steps of:

(a) receiving the leakage of the electromagnetic energy;

(b) deriving a frequency domain distribution of the electromagnetic energy; and

(c) identifying the carrier frequency from the frequency domain distribution.

22. The method of claim 21, wherein said identifying the carrier frequency further comprises the step of:

(d) converting the electromagnetic energy to a digital format.

23. The method of claim 18, wherein said identifying the first channel step comprises the step of:

(1) identifying a carrier frequency of the first channel to which the receiver is tuned from an electromagnetic signal transmitted from a remote control unit for the receiver.

24. The method of claim 23, wherein the electromagnetic signal is at an infrared frequency.

25. The method of claim 23, wherein said identifying the carrier frequency step comprises the steps of:

(a) receiving the electromagnetic signal;

(b) deriving a frequency domain distribution of the electromagnetic signal; and

(c) identifying the carrier frequency from the frequency domain distribution.

26. The method of claim 25, wherein said identifying the carrier frequency step further comprises the step of:

(d) converting the electromagnetic signal to a digital format.

27. The method of claim 18, wherein said cross-referencing step comprises the steps of:

(a) receiving first data that identifies the first channel;

(b) cross-referencing the first data with second data that identifies the second channel; and

(c) producing the second data.

28. A method for processing a signal, comprising the steps of:

(1) identifying the signal as having one of a first format and a second format; and

(2) converting, if said identified signal has the first format, said identified signal from the first format to the second format.

wherein the first format is one of an analog format and a digital format and the second format is one of the analog format and the digital format, but different from the first format.

29. The method of claim 28, wherein the signal is a radio frequency signal.

30. The method of claim 28, further comprising the step of:

(3) conveying, if said identified signal has the second format, said identified signal.

31. The method of claim 28, further comprising the step of:

(3) converting the signal from being centered at a first frequency to being centered at a second frequency.

32. The method of claim 28, further comprising the steps of:

(3) demodulating the signal; and

(4) encoding the signal.

33. The method of claim 32, further comprising the step of:

(5) converting the signal from being centered at a first frequency to being centered at a second frequency.

34. The method of claim 32, further comprising the steps of:

(5) demultiplexing the signal to a first channel and to a second channel; and

(6) isolating the first channel from the second channel.

35. The method of claim 34, further comprising the step of:

(7) combining the first channel with the second channel.

36. The method of claim 28, wherein said identifying step comprises the step of:

(1) determining if an energy within a frequency band of the signal is greater than a threshold energy.

37. The method of claim 36, wherein the frequency band is within a channel of the signal.

38. The method of claim 36, wherein said determining step comprises the steps of:

(a) isolating the energy within the frequency band; and

(b) comparing the energy within the frequency band with the threshold energy.