WO2015171283A1

WO2015171283A1 - Method and apparatus for duplicating an output on multiple modulated rf outputs

Info

Publication number: WO2015171283A1
Application number: PCT/US2015/026099
Authority: WO
Inventors: Thomas Edward Horlander
Original assignee: Thomson Licensing
Priority date: 2014-05-09
Filing date: 2015-04-16
Publication date: 2015-11-12

Abstract

An apparatus and method of for outputting an analog signal is provided. An input receives an input signal and a modulation unit modulates the received input signal onto at least two carrier signals, each of the at least two carrier signals being associated a respective channels. The modulation unit combines the modulated at least two carrier signals for display on respective channels of a display device.

Description

METHOD AND APPARATUS FOR DUPLICATING AN OUTPUT ON MULTIPLE

MODULATED RF OUTPUTS

BACKGROUND OF THE INVENTION

Despite the requirement that cable and satellite television providers broadcast their content as digital signals, which are commonly associated with high definition (HD) television, there are still a significant number of display devices that are not capable of displaying the high definition portions of these signals. Thus, cable and satellite providers also transmit standard definition versions of the content. Set top boxes issued to the consumer by the cable/satellite provider receive and decode these signals for output to a display (e.g. television). In the instance when the signal to be output is transmitted to a display device only capable of displaying standard definition signals, the signals are generally output via an RF modulator coupled to an output terminal (e.g. F- connector). In conventional systems, RF modulated audio-video signals are output on a particular channel, from a set of channels wherein each channel has a unique frequency associated therewith. Exemplary components of an RF video signal and their position within the frequency spectrum are shown in Figure 1 . The channel is formed from a six (6) MHz frequency band and within which various components of the RF video signal are positioned. The RF modulator outputs an RF modulated video signal that includes a video (picture) carrier that is amplitude modulated (AM) on the carrier waveform, a color carrier which is phase modulated (PM) and an audio carrier which is frequency modulated (FM) on the carrier waveform. The RF video signal also includes vestigial side bands that extend between the lower boundary of the channel spectrum and the beginning of the video carrier and above the audio carrier through the upper boundary of the channel spectrum. The video carrier begins at 1 .25 MHz above the lower bound of the channel and has a 4 MHz bandwidth. The color carrier, also known as the color burst, is positioned at 3.579545 MHz or 3.58 MHz above the start of the video carrier. The phase modulated color carrier includes the pictures color or chroma signal. The audio carrier is positioned at 4.50 MHz above the visual carrier (or 250 kHz from the upper boundary of the channel) and has a 50 kHz bandwidth.

In order for a respective video signal to be output to analog television, it must be output on a single 6 MHz channel in the VHF and/or UHF video spectrums. For example, in North America, RF modulators output to either channel 3 which has its lower boundary at 60MHz and its upper boundary 66 MHz or channel 4 which has its lower boundary at 66MHz and its upper boundary at 72Mhz. Generally, it is up to a user to select a channel having a predetermined frequency from the set of channels. To effect this selection, at least one switch, either externally connector or integrally formed with the RF modulator, is required thereby adding to the cost of producing the circuitry. Moreover, the selection of the channel on which to output the signal must be manually made by a user upon initial setup. Drawbacks associated with the conventional RF circuitry include the additional cost associated with the output of a standard definition signal and the requirement that a user manually determine and select the channel on which the RF modulated video signal may be viewed. Thus, it is desirable to overcome these and other problems associated with the output of RF modulated video signals. SUMMARY OF THE INVENTION

In one embodiment, an apparatus for outputting an analog signal is provided. An input receives an input signal and a modulation unit modulates the received input signal onto at least two carrier signals, each of the at least two carrier signals being associated a respective channels. The modulation unit combines the modulated at least two carrier signals for display on respective channels of a display device. In another embodiment, a method of outputting an analog signal is provided. The method includes receiving an input signal at an input connector and modulating the received input signal onto at least two carrier signals, each of the at least two carrier signals being associated a respective channels. The modulated at least two carrier signals are combined for display on respective channels of a display device.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of the present disclosure will be described or become apparent from the following detailed description of the preferred embodiments, which is to be read in connection with the accompanying drawings.

In the drawings, wherein like reference numerals denote similar elements throughout the views: FIG. 1 is a prior art illustration of the spectrum of a video signal on a particular channel;

FIG. 2 shows an exemplary block diagram of a device for receiving and outputting audio video data on a display device according to invention principles;

FIG. 3 shows a block diagram of an RF modulator according to invention principles;

FIG. 4 illustrates the spectrum of the signal output by the RF modulator according to invention principles;

FIG. 5 shows an exemplary block diagram of a device for receiving and outputting audio video data on a display device according to invention principles; and FIG. 6 is a flow diagram detailing the operation of the RF modulator according to invention principles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The exemplifications set out herein illustrate preferred embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

The system according to invention principles advantageously provides a method and apparatus that receives, decodes and output an audio-video signal on an analog display device. The system according to invention principles utilizes a novel RF modulator that automatically modulates an audio video (AV) signal onto at least two different channels and combines the signal into a single output signal able to be tuned by the user. The automatic modulation of the AV signal onto at least two channels advantageously enables the apparatus to continually output the desired AV signal no matter the channel tuned by the user. By automatically outputting the AV signal onto two channels, a user no longer has to manually and externally configure the apparatus to define the channel to which the AV signal will be output. This presents an advantage when looking to the cost and design of the apparatus. Currently, there are still a significant number of standard definition and/or analog display devices that are used to view AV signals (e.g. television signals). Because of the continued existence of these output devices, device manufacturers that design and produce devices for receiving, decoding and outputting AV content received from a content provider (e.g. cable, satellite, and/or broadcaster) must continue to use circuitry able to provide an analog output of the AV content. Along with the circuitry for implementing the analog output, systems engineers are required to code software routines that control the operation of the circuits which provide the analog output. The apparatus according to invention principles, reduces the cost to produce these devices because there is no longer a need for a switch component that was previously used to configure the RF modulator responsible for generating the analog output. Instead, the RF modulator according to invention principles may be automatically configured to output the analog signal onto at least two channels, eliminating the need for the user to select an output channel as well as the need for switching circuitry that would be required to implement a manual selection by a user.

Referring to FIG. 2, a block diagram of an exemplary device 200 for receiving audio video content from a content provider and outputting the received content for display is shown. In one embodiment, the device 200 is a set top box that is provided to a user by a cable or satellite provider. In another embodiment, the device 200 may be a set top box that can receive and tune unencrypted broadcast television signals. These are merely two exemplary embodiments, and any device able to receive an AV input signal and process the received signal for output on at least one of a digital and analog display device may include the novel components described herein. The device 200 includes a controller 202 that selectively controls the operation of the device. The controller 202 executes any and all instructions for operating the device 200 and to enable the device 200 to receive at least one AV input signal and decode or otherwise process (e.g. tune) the AV input signal for output to a display device. The device 200 includes a plurality of common components that are known in the art of set top box design and manufacture.

The controller 202 may be connected to at least one visual indicator 204 (e.g. an LED indicator) and may selectively illuminate the at least one visual indicator according to predetermined rules to provide the user with information about the operation of the device. In one example, the controller 202 may selectively illuminate the at least one visual indicator 204 to provide status information to the user prompting the user to take certain action. In another example, the controller 202 may selectively illuminate the at least one visual indicator 204 to indicate that the device is operating as intended. These are merely examples and the controller 202 may include and execute instructions to illuminate the at least one visual indicator 204 in any manner for any purpose.

An infrared (IR) receiver 206 may also be coupled to the controller 202 to selectively receive control signals from a user via a remote control. The control signals may be issued by the user to selectively tune the channel that is to be decoded and output for display. The control signals may also be used to control other system functionality such as a digital video recording module that enables the user to select and view previously recorded television programs. The control signals may also cause the controller 202 to access an "on-demand" module that presents, to a user, a set of AV content that is accessible and may be output for display on a display device.

Additionally, the control signals may cause the controller 202 to selectively control the operation of a secondary device (not shown) that is connected to device 200. In one embodiment, the secondary device may be a Blu-ray or DVD player coupled to the device 200 and which can be controlled thereby. These control signals are described for purposes of example only and the IR receiver 206 may receive any type of control signal from a remote control that may be used to control any functionality of device 200.

The controller 202 may receive clock signals for controlling the timing operation and signal syncing operation from an oscillator 208. The controller also includes S-Flash module 210, a NAND-Flash module 212 and DDR Memory module 214. The S-Flash (serial flash) will hold some portion of the software which is executed by the controller. The S-Flash may also hold system information which must be retained between system power cycles. The NAND-Flash will hold some portion of the software which is executed by the controller as well as non-software information such as graphics widgets which are used during the normal operation of the system. The NAND-Flash may also hold system information which must be retained between system power cycles. The DDR memory is used by the system for temporary storage of software and non-software system data. Examples of non-software system data are buffers for compressed audio and video data, buffers for decompressed audio and video data, and data rate smoothing buffers for high speed system interfaces.

A network port 216 is coupled to the controller 202 for providing local and wide area networking capabilities to the device 200. The controller 202 enables bidirectional communication between the device 200 and at least one of a local area network and wide area network (e.g. internet). The network port may be an Ethernet port enabling hardwired network communication or a wireless network module (WIFI) enabling wireless communication between the device 200 and any other device on any other network. In one embodiment, the controller 202 may selectively transmit and receive data packets over a local area packet-switched network thereby communicating with other devices (e.g. other set top boxes, computers, tablets, smartphones, etc) on the local area network. In another embodiment, the controller 202 may issue requests, either automatically or in response to user selection, for data located on the internet. The controller 202 may selectively address the packets for receipt by the proper resource on the internet and provide the requested data to the device 200. These operations are merely used to illustrate exemplary networking operation and persons skilled in the art will understand that any type of bidirectional communication may be facilitated by the controller 202 using the networking port 216.

The controller 202, in addition to controlling the general operation of the device 200, also receives and processes AV input signals for display on at least one type of display device. An AV input 220 is coupled to the controller 202 and receives an input AV signal from a content provider. The input signal received at AV input 220 is a digital AV input signal. In one embodiment, the AV input signal receive at AV input 220 is a QAM formatted AV input signal. In another embodiment, the AV input signal received at AV input 220 is an MPEG formatted AV input signal. These types of AV input signals are described for purposes of example only and any AV input signal of any type and/or format may be received at AV input 220. The controller 202 receives the AV input signal from the AV input 220 and selectively processes the signal for output on at least two types of display devices.

In one embodiment, the controller 202 includes an MPEG decoder 203 and associated circuitry as known in the art. The MPEG decoder 203 of the controller 202 may selectively decode an MPEG-formatted AV input signal that is received via the AV input 220. Upon decoding the MPEG formatted AV input signal, the controller 202 may selectively cause the decoded signal to be output via a digital output 222 (e.g. HDMI port) for display on a digital display device (e.g. HDTV - not shown). Alternatively, should the device 200 not be connected to a digital display via digital output 222, the controller 202 may provide the decoded AV input signal to a modulation unit 205 for appropriate modulation for output via an analog output port 224 and display on an analog display device.

Turning now to FIG. 3, a block diagram of the modulation unit 205 of controller 202 is shown. The modulation unit 205 is embodied as a digital signal processing unit that is able to receive digital video and digital audio signals decoded from the received digital AV input signal and modulate these signals for output as RF modulated analog signals.

Prior to modulation via modulation unit 205, a desired channel of the digital AV input signal is selectively tuned by the user, for example, using the remote control device. The controller 202 decodes the AV data on the selected channel into a video component 302 and audio component 304. The modulation unit 205 includes a first input terminal 303 for receiving the decoded video component 302 and a second input terminal 305 for receiving the decoded audio component 304.The audio component 304 is provided to a Broadcast Television Systems Committee (BTSC) audio encoder for use in encoding multichannel television sound (MTS) as is known in the art. The encoded MTS audio signal 306 is provided, along with the decoded video component 302, to a first combiner 308. The first combiner 308 modulates the video component 302 and audio component 304 onto an RF carrier signal and output as composite AV signal 309.

The inputs to the modulation unit 205 are digital data streams representing color video and stereo audio. The encoding, modulation and combining steps may be implemented in the digital domain by a digital signal processor The inputs to the modulation may be color digital video and stereo digital audio or may be mono digital audio or black and white digital video.

The composite AV signal 309 is provided to a first channel modulation unit 310 and a second channel modulation unit 312. The first channel modulation unit 310 further modulates the composite signal 309 onto a first output channel having a first frequency band. The second channel modulation unit 312 also further modulates the composite signal 309 onto a second output channel having a second, different frequency band. The first and second channel modulation units 310 and 312, respectively, modulate the composite signal 309 according to the National Television System Committee (NTSC) standard such as described above in FIG. 1 .

In one embodiment, the frequency bands of the first output channel and second output channel are sequentially positioned such that the frequency band of the first output channel is less than the frequency band of the second output channel. For example, in an embodiment where the device is configured to receive and process North American television channels, the first output channel is channel 3 in the VHF spectrum having a lower channel boundary at 60 MHz and an upper channel boundary at 66 MHz. In this embodiment, the first channel modulation unit 310 amplitude modulates the video component 302 of the composite signal 309 onto an RF carrier signal at 61 .25 MHz and frequency modulates the audio component 304 at 65.75 MHz. The color carrier is phase modulated onto the RF carrier at 3.58 MHz above 61 .25 MHz. Additionally, in this embodiment, the second output channel may be channel 4 in the VHF spectrum having a lower channel boundary at 66 MHz and an upper channel boundary at 72 MHz. In this embodiment, the second channel modulation unit 312 amplitude modulates the video component 302 of the composite signal 309 onto an RF carrier signal at 67.25 MHz and frequency modulates the audio component 304 at 71 .75 MHz. The color carrier is phase modulated onto the RF carrier at 3.58 MHz above 66.25 MHz.

The modulation unit 205 includes a second combiner 314 that receives the first and second channel modulated signals and combines them into a composite modulated output signal 316 which is then provided to a digital to analog converter (D/A) 318. The D/A converter 318 converts the composite modulated output signal 316 from digital to analog for output via the analog output 224. One exemplary method to combine the digital data streams output from each modulation function is to sample rate convert each data stream into a common sample rate and add the values of each signal at each computed sample point. Each modulation function may be implemented such that the sample rates are common between the two processes. In this case the combine function would be an addition of the two data streams. The combine function may also incorporate any clipping or rounding necessary to map the output of the combine function to the input of the D/A. An exemplary composite modulated signal output by the D/A converter 318 in FIG. 3 is shown in FIG. 4. This composite signal 400 shows the frequency spectrum of the analog signal output by the D/A converter.

When a user uses an analog display device that is connected to the AV output, the user no longer has to selectively determine the channel that the analog display device is tuned to in order to receive and display the analog signal. Because, when the D/A converter outputs an analog composite modulated output signal on either the first channel (e.g. Channel 3) or the second channel (e.g. Channel 4) the data on either channel will be automatically output for display. This minimizes the cost associated with producing the device 200 because it eliminates the need for a switch to manually switch the modulator from modulating for one channel or the other. Instead, the modulation unit 205 automatically modulates the AV signal onto the at least two channels that are used for outputting analog AV signals. This further minimizes any disruption in viewing or otherwise consuming the desired content. For example, in the event of an inadvertent channel change on the display device, the simultaneous output of the AV signal on two channels will minimize (or eliminate) any disruption to the user as they will continue to view the same content despite the channel change.

While the above described example uses the frequency spectrum for analog output for North America, one skilled in the art will readily appreciate that the modulation unit may be selectively configured to automatically modulate the RF carrier on the accepted channel based on the geographic location of the device 200. For example, in Europe, the modulation unit 205 may automatically modulate the AV input signal onto channel 36 in the UHF frequency spectrum. Alternatively, in the European Region, the modulators may be selectively tuned to any channel within the UHF spectrum. Thus, the modulation unit 205 may be configured to modulate the AV input signal on any channel in the UHF spectrum. These are described for purposes of example only and the controller 202 may be preconfigured, depending on the geographic region that the device 200 will be deployed, to modulate the decoded AV input signal to a particular channel or channels designated for outputting analog video to an analog display device.

FIG. 5 is an alternate embodiment of an exemplary device 500 for receiving audio video content from a content provider and outputting the received content for display. Device 500 includes certain similar components as described above with respect to FIG. 2. Thus, components having the same reference numerals as those in FIG. 2 operate in a like manner and need not be discussed further. The device 500 includes a controller 502 for controlling the operation and functions of the device 500. Controller 502 includes and executes all of the same instructions as controller 202 described in FIG. 2. In this embodiment, controller 502 further advantageously and automatically determines the channel on which the analog video signal should be output using GPS data. The controller 502 includes a GPS unit 504 that may receive GPS data from an external source of GPS information that identifies a region where the device 500 is deployed. For example, the controller 502 may control the GPS unit 504 to query a GPS satellite or other source of GPS data via the network connector 216. Upon receipt of the requested GPS data, the controller 502 may analyze the GPS data to determine a location of the device. Upon determining the location of the device, the controller 502 may query a repository of analog output channels that are organized by region and select the appropriate channel that corresponds to the region as indicated by the GPS data. The controller 502 configures the modulation unit 505 to modulate the decoded AV input signal onto an RF carrier using the channel that corresponds to the region. In this manner, the modulation unit 505 is selectively tunable based on location data thereby enabling the device to be deployed in multiple geographic regions without having to go through a costly configuration process prior to deployment. The modulation unit 505 described herein is similar to the modulation unit 205 described in FIG. 3. However, in this embodiment, the channel modulation units 310 and 312 are selectively configurable by the controller 502 to output signals at respective frequencies related to the geographic region determined by the GPS. For example, if device 500 was deployed in the United States, the GPS unit 504 would request location data from a GPS satellite. The returned GPS data would indicate deployment in the United States and the controller 502 would query a repository (either locally stored, or accessible via the network connection) of analog output channels. This query would indicate that the modulation unit is to output a first analog output signal on a first channel (Channel 3) and a second analog output signal on a second channel (Channel 4). Thus, the controller 502 would configure the first channel modulator 310 in FIG. 3 to modulate the output signal with the frequency spectrum associated with Channel 3 and configure the second channel modulator 312 in FIG. 3 to modulate the output signal with the frequency spectrum associated with Channel 4.

FIG. 6 represents an algorithm detailing an exemplary operation of the device discussed above with respect to FIGS 2 - 5. The algorithm described herein provides a method of outputting an analog signal. In step 602, an input signal is received at an input connector. In step 604, the received input signal is modulated, by a modulation unit, onto at least two carrier signals, each of the at least two carrier signals being associated a respective channels. In one embodiment, the modulation unit RF modulates the receive input signals onto the at least two carrier signals. In step 606, the modulated at least two carrier signals are combined for display on respective channels of a display device.

In one embodiment, the input signal received in step 602 is an audiovisual input signal including first, second and third components and the modulation in step 604 includes modulating the first component using a first type of modulation, modulating the second component using a second type of modulation, and modulating the third component using a third type of modulation. For example, the first component is a video signal which is modulated using amplitude modulation, the second component is a color component that is modulated using phase modulation, and the third component is an audio signal that is modulated using frequency modulation. In another embodiment, prior to modulation by the modulation unit, the input signal is decoded into an audio signal and a video signal and is provided to the modulation unit for modulation thereof.

In a further embodiment, the input signal is decoded into a first type of input signal having a first format and a second type of input signal having a second format. In this embodiment, the modulation unit includes an audio encoder that encodes the second type of input signal into the first format. A combiner of the modulation unit combines the first type of input signal and the encoded second type of input signal into a third signal. The third signal is modulated by a first modulator onto a carrier of one of the at least two channels. The third signal is also modulated by a second modulator onto a carrier of an other of the at least two channels. A second combiner combines the modulated third signal output by the first and second channel modulators to generate the output signal. The modulation unit may also include a digital to analog converter to convert the input signal from a digital input signal into an analog input signal.

It should be understood that the elements shown and discussed above, may be implemented in various forms of hardware, software or combinations thereof. Preferably, these elements are implemented in a combination of hardware and software on one or more appropriately programmed general-purpose devices, which may include a processor, memory and input/output interfaces. The present description illustrates the principles of the present disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its scope. All examples and conditional language recited herein are intended for informational purposes to aid the reader in understanding the principles of the disclosure and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. Thus, for example, it will be appreciated by those skilled in the art that the block diagrams presented herewith represent conceptual views of illustrative circuitry embodying the principles of the disclosure. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudocode, and the like represent various processes which may be substantially represented in computer readable media and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

Claims

CLAIMS:

1 . An apparatus for outputting an analog signal comprising

an input that receives an input signal; and

a modulation unit that modulates the received input signal onto at least two carrier signals, each of the at least two carrier signals being associated a respective channels, and combines the modulated at least two carrier signals for display on respective channels of a display device.

2. The apparatus of claim 1 , wherein

the input signal is an audiovisual input signal including first, second and third components.

3. The apparatus of claim 2, wherein

said modulation unit modulates

the first component using a first type of modulation,

the second component using a second type of modulation, and the third component using a third type of modulation.

4. The apparatus of claim 2, wherein

the first component is a video signal, the second component is a color component and the third component is an audio signal.

5. The apparatus of claim 1 , wherein the modulation unit RF modulates the received input signal onto the at least two carrier signals.

6. The apparatus of claim 1 , further comprising a controller that decodes the input signal into an audio signal and a video signal, and provides the audio signal and video signal to the modulation unit for modulation thereof.

7. The apparatus of claim 1 , wherein the input signal is decoded into a first type of input signal having a first format and a second type of input signal having a second format.

8. The apparatus of claim 7, wherein the modulation unit includes

an audio encoder that encodes the second type of input signal into the first format;

a first combiner that combines the first type of input signal and the encoded second type of input signal into a third signal;

a first channel modulator that modulates the third signal onto a carrier of one of the at least two channels;

a second channel modulator that modulates the third signal onto a carrier of an other of the at least two channels; and

a second combiner that combines the modulated third signal output by the first and second channel modulators to generate the output signal.

9. The apparatus of claim 1 , further comprising

a controller that controls on which of the at least two channels the input signal is modulated.

10. The apparatus of claim 1 , wherein the input signal is a digital input signal and the modulation unit includes a digital to audio converter that converts the output signal into an analog output signal.

1 1 . A method of outputting an analog signal comprising the activities of receiving an input signal at an input connector;

modulating the received input signal onto at least two carrier signals, each of the at least two carrier signals being associated a respective channels; and combining the modulated at least two carrier signals for display on respective channels of a display device.

12. The method of claim 1 1 , wherein

The method of claim 12, further comprising

modulating the first component using a first type of modulation;

modulating the second component using a second type of modulation; modulating the third component using a third type of modulation.

14. The method of claim 2, wherein

15. The method of claim 1 1 , wherein the activity of modulating includes RF modulating the received input signal onto the at least two carrier signals.

16. The method of claim 1 1 , further comprising

decoding the input signal into an audio signal and a video signal; and providing the audio signal and video signal for modulation thereof.

17. The method of claim 1 1 , further comprising

decoding the input signal is decoded into a first type of input signal having a first format and a second type of input signal having a second format.

18. The method of claim 17, further comprising

encoding, by an audio encoder, the second type of input signal into the first format;

combining, by a first combiner, the first type of input signal and the encoded second type of input signal into a third signal;

modulating the third signal, by a first modulator, onto a carrier of one of the at least two channels;

modulating the third signal, by a second modulator, onto a carrier of an other of the at least two channels; and

combining, by a second combiner, the modulated third signal output by the first and second channel modulators to generate the output signal.

19. The method of claim 1 1 , further comprising

controlling, by a controller, which of the at least two channels the input signal is modulated.

20. The method of claim 1 1 , wherein the input signal is a digital input signal and further comprising, converting the output signal into an analog signal using a digital to analog converter.