WO2011034571A1

WO2011034571A1 - Studio to transmitter link signaling method and apparatus

Info

Publication number: WO2011034571A1
Application number: PCT/US2010/002492
Authority: WO
Inventors: Aaron Reel Bouillet
Original assignee: Thomson Licensing
Priority date: 2009-09-15
Filing date: 2010-09-14
Publication date: 2011-03-24

Abstract

A method and architecture for processing signal communications between over a studio to transmitter link. Specifically, a multiplexer, or the like, is operative to substitute transmitter synchronization and/or control information for known data bits, such as packet identification bits or training bits within an ATSC M/H packet to transmission to a transmitter and/or exciter. The exciter then extracts the control data and replaces the control data within the packet with the known data bits.

Description

Studio to Transmitter Link Signaling Method and Apparatus

Priority Claim

This application claims the benefit of United States Provisional Patent Application No. 61/242,518 entitled "Studio to Transmitter Link Signaling Method" which are incorporated herein by reference.

Field of the Invention

The present invention relates to transmitting information between a content generation site, such as a studio, and a transmitter. In particular, the present invention relates to a transmission system wherein synchronization and control information is inserted in the transport header of ATSC M/H packets or in training byte locations within the ATSC M/H transport stream. Background of the Invention

Over the past decades, video transmission systems have migrated from analog to digital formats. In the United States, broadcasters are in the final stages of completing the switch from the National Television System Committee (NTSC) analog television system, to the Advanced Television Systems Committee (ATSC) A/53 digital television system. The A/53 standard provides "specification of the parameters of the system including the video encoder input scanning formats and the preprocessing and compression parameters of the video encoder, the audio encoder input signal format and the pre-processing and compression parameters of the audio encoder, the service multiplex and transport layer characteristics and normative specifications, and the VSB RF/Transmission subsystem." The A/53 standard defines how source data (e.g., digital audio and video data) should be processed and modulated into a signal that is to be transmitted over the air. This processing adds redundant information to the source data so that a receiver may recover the source data even if the channel adds noise and multi- path interference to the transmitted signal. The redundant information added to the source data reduces the effective rate at which the source data is transmitted, but increases the potential for successful recovery of the source data from a received signal. The ATSC A/53 standard development process was focused on HDTV and fixed reception. The system was designed to maximize video bit rate for the large high resolution television screens that were already beginning to enter the market.

Transmissions broadcast under the ATSC A/53 standard, however, present difficulties for mobile receivers. Enhancements to the standard are required for robust reception of digital television signals by mobile devices.

Recognizing this fact, in 2007, the ATSC announced the launch of a process to develop a standard that would enable broadcasters to deliver television content and data to mobile and handheld devices via their digital broadcast signal. Multiple proposals were received in response. The resulting standard, to be called ATSC-M/H, is intended to be backwards compatible with ATSC A/53, allowing operation of existing ATSC services in the same RF channel without an adverse impact on existing receiving equipment.

Many systems for transmission to mobile devices, such as some proposed ATSC-M/H systems, perform periodic transmission. Such systems can include a preamble in their transmissions in order to assist with receiver system operation.

Preambles typically include known information that portions of the receiving system may use for training to improve reception, which can be particularly useful in difficult environments such as those found in mobile operation. The training byte locations are known, and are typically filled with known sequences described in the ATSC M/H standard. Such systems may further include transport headers for the packets. The transport header consists of a sync byte (0x47) followed by 3 additional bytes numbered 1 , 2, and 3.

A common problem in studio to transmitter link communications is the large amounts of data required to be sent from the studio to the transmitter. Often a broadcast transmitter is not co-located with the studio that originates the content as the studio is not in an optimal broadcast location. For example, a transmitter may be placed on the top of a mountain or a skyscraper where a shorter tower can be used. These sites however are not practical for a studio location. Even in flat areas, the center of a station's allowed coverage area may not be near the studio or may be in a densely populated area where locating a transmitter tower may meet community opposition. Thus, the transmitter must be placed in a different location, even up to miles away from the studio. Depending on the locations that must be connected, a station may choose either a point to point (PTP) link on another special radio frequency, or an all-digital wired link via a dedicated T1 or E1 (or larger-capacity) line. Radio links can also be digital, or the older analog type, or a hybrid of the two. Even on older all-analog systems, multiple audio and data channels can be sent using subcarriers. Television studios commonly transmit a standard definition channel, one or more high definition programs, and now ATSC M/H signals. This taxes the limited bandwidth of the expensive studio to transmitter link. Not only does the payload data destined for transmission need to be communicated, but control and synchronization information for the transmitter also needs to be transmitted, thereby reducing the bandwidth available for payload data. It is desirable to transmit transmitter control and synchronization information in a manner which does not consume the limited bandwidth of the studio to transmitter link. The present invention described herein addresses this and/or other problems.

Summary of-the Invention

In accordance with an aspect of the present invention, a method of communication comprising the steps of receiving encoded television program data, generating a packet comprising said encoded television data and transmitter control information, and transmitting said packet to a transmitter is disclosed.

In accordance with another aspect of the present invention a method of communication comprising the steps of receiving an encoded packet comprising control data and encoded television data, extracting said control data from said encoded packet, generating a transmission packet comprising said encoded television data and standard data wherein said standard data replaces said control data in said encoded packet, and transmitting said transmission packet to a transmitter. Description of the Drawings

FIG. 1 is a block diagram of an embodiment of a terrestrial broadcast transmitter for mobile/handheld reception of the present disclosure;

FIG. 2 is a block diagram of an embodiment of a portion of an exemplary

mobile/handheld data stream of the present disclosure;

FIG. 3 is a block diagram of an embodiment of an exemplary data frame of the present disclosure;;

FIG. 4 is a block diagram of an exemplary embodiment of a studio to transmitter link; FIG. 5 is a block diagram of an exemplary embodiment of an ATSC M/H transport block according to the present disclosure;

FIG. 6 is a block diagram of another exemplary embodiment of an ATSC M/H transport block according to the present disclosure;

FIG. 7 is a state diagram of an exemplary embodiment of a method of transmitting data in a studio to transmitter link according to the present invention.

Fig. 8 is a state diagram of another exemplary embodiment of a method of transmitting data in a studio to transmitter link according to the present invention.

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.

Description of the Preferred Embodiment As described herein, the present invention provides a method and apparatus for enabling communications within a studio to transmitter link by substituting control and synchronization information for know data bits within an ATSC M/H packet. While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims. For instance, the described technique could be applicable to transmission systems designed for other types of data or that use different coding, error-correction, redundancy, interleaving, or modulation schemes. Referring now to the drawings, and more particularly to FIG. 1 , a block diagram of an embodiment of a terrestrial broadcast transmitter for mobile/handheld reception of the present disclosure is shown. Embodiment 100 of FIG. 1 comprises a plurality of signal transmitting means such as an MPEG Transport stream source 105, an ATSC M/H frame encoder 110, a block processor 120, a group formatter 115, a packet formatter 125, a packet multiplexer 130, a signal encoder 135, a data randomizer 140, a first Reed Solomon encoder 145, an interleaver 150, a parity replace means 155, a trellis encoder 165, a second reed Solomon encoder 160, a synchronization multiplexer 170, a pilot inserter 175, a pre-equalization filter 180, an 8 VSB modulator 185, a radio frequency up converter 190 and an antenna 195..

In the ATSC-M/H preprocessing flow, incoming MPEG transport data from an MPEG transport stream source 110 is received at the ATSC M/H frame encoder. The ATSC M/H frame encoder 110 receives the MPEG transport data and arranges the data according to the ATSC A/153 standard for a data frame. The ATSC M/H data frame established the location of the M/H content with the VBS Frames and allows for processing by an M/H receiver. One M/H frame is equivalent in size to 20 VSB frames and has an offset of 37 transport stream packets relative to the beginning of each VSB frame. The frame encoded ATSC M/H data is then coupled to the block processor. The ATSC M/H block processor 120 is operative to receive the framed data from the ATSC and outer-encode the date for the output of the Reed Solomon frame encoder. The operations of the block processor include RS frame portion to SCCC (Serially Concatenated Convolutional Code) block conversion, byte to bit conversion,

convolutional encoding, symbol interleaving, symbol to byte conversion and SCCC block to M/H block conversion.

The group formatter 115 maps the FEC coded M H service data from the block processor into corresponding M/H blocks of a group, adds the predetermined training data bytes, adds the PCCC encoded signaling data, and the data bytes to be used for initializing the trellis encoder memories. It also inserts place-holder bytes for main data service, MPEG 2 headers and non-systematic RS parity, and some dummy data bytes to complete the construction of the intended group format.

The group formatter 115 is responsive to the signaling encoder 135. The signaling encoder 135 supplies data used for signaling the ATSC M/H receivers via PCCC encoded signaling data. This data is incorporated into the ATSC M/H stream by the group formatter 115.

The packet formatter 125 receives data from the group formatter 115 and arranges the data to output 118 M/H data encapsulating TS packets per group. The packet formatter removes main data service and RS placeholders, and replaces the 3 byte MPEG header place holder with an MPEG header having an MHE packet PID. An MPEG TS sync byte is also inserted before each 187-byte data packet.

The packet multiplexer 130 receives data from the packet formatter 125 and multiplexes the M/H services TS packets and the main service TS packets to construct M/H frames. The ATSC-M/H data stream is then processed by the legacy ATSC A/53 path, including data randomizer 140, first Reed-Solomon encoder 145, interleaver 150, trellis encoder 165, second Reed Solomon encoder 160, sync multiplexer 170, pilot insertion 175, Pie-equalization filter 180, and modulation 185. In the data randomizer 140, each byte value is changed according to known pattern of pseudo-random number generation. This process is reversed in the receiver in order to recover the proper data values. With the exception of the segment and field syncs, it is desirable for the 8-VSB bit stream to have a completely random, noise-like nature to afford the transmitted signal frequency response must have a flat noise-like spectrum in order to use the allotted channel space with maximum efficiency. The data is then coupled to the first Reed-Solomon encoder 145, where Reed-

Solomon (RS) coding provides additional error correction potential at the receiver through the addition of additional data to the transmitted stream. In an exemplary embodiment, the RS code used in the VSB transmission system is a t = I0 (207,187) code. The RS data block size is 187 bytes, with 20 RS parity bytes added for error correction. A total RS block size of 207 bytes is transmitted per RS code word. In creating bytes from the serial bit stream, the MSB shall be the first serial bit and the 20 RS parity bytes are sent at the end of the data block or RS code word.

The byte interleaver 150 then processes the output of the first Reed-Solomon encoder 145. Interleaving is a common technique for dealing with burst errors that can occur during transmission. Without interleaving, a burst error could have a large impact on one particular segment of the data, thereby rendering that segment uncorrectable. If the data is interleaved prior to transmission, however, the effect of a burst error can be effectively spread across multiple data segments. Rather than large errors being introduced in one localized segment that cannot be corrected, smaller errors may be introduced in multiple segments that are each separately within the correction capabilities of forward error correction, parity bit, or other data integrity schemes. For instance, a common (255, 223) Reed-Solomon code will allow correction of up to 16 symbol errors in each code word. If the Reed-Solomon coded data is interleaved before transmission, a long error burst is more likely to be spread across multiple codewords after deinterleaving, reducing the chances that more than the correctable 16 symbol errors are present in any particular codeword.

The interleaver 150 employed in a VSB transmission system is a 52 data segment (intersegment) convolutional byte interleaver. Interleaving is provided to a depth of about 1/6 of a data field (4 ms deep). Only data bytes are interleaved. The interleaver is synchronized to the first data byte of the data field. Intrasegment interleaving is also performed for the benefit of the trellis coding process.

The interleaved data is then coupled to the second RS encoder 160 and parity replacer 155. The RS parity data calculated prior to the trellis initialization will be erroneous and must be replaced to ensure backwards compatibility. Thus, the trellis encoder 165 will supply the changed initialization byte to the second RS encoder which recalculates the RS parity of the corresponding M/H packets. The new RS parity bits are then supplied to the parity replacer 155. The parity replacer 155 selects the output of the data interleaver 150 as the data bytes in the packet, and the output of the second RS encoder as the RS parity. This data is then supplied to the trellis encoder 165.

The signal is then coupled to the Trellis encoder 165. Trellis coding is another form of Forward Error Correction. Unlike Reed-Solomon coding, which treats the entire MPEG-2 packet simultaneously as a block, trellis coding is an evolving code that tracks the progressing stream of bits as it develops through time. Accordingly, Reed-Solomon coding is known as a form of block code, while trellis coding is a convolutional code. In ATSC trellis coding, each 8-bit byte is split up into a stream of four, 2-bit words.

In the trellis coder, each 2-bit word that arrives is compared to the past history of previous 2-bit words. A 3-bit binary code is mathematically generated to describe the transition from the previous 2-bit word to the current one. These 3-bit codes are substituted for the original 2-bit words and transmitted over-the-air as the eight level symbols of 8-VSB (3 bits = 8 combinations or levels). For every two bits that go into the trellis coder, three bits come out. For this reason, the trellis coder in the 8-VSB system is said to be a 2/3 rate coder. The signaling waveform used with the trellis code is an 8- level (3 bit) one-dimensional constellation. The transmitted signal is referred to as 8 VSB. A 4-state trellis encoder shall be used.

In an exemplary embodiment, trellis code intra-segment interleaving is used. This uses twelve identical trellis encoders and precoders operating on interleaved data symbols. The code interleaving is accomplished by encoding symbols (0, 12, 24 36 ...) as one group, symbols (1 , 13, 25, 37, ...) as a second group, symbols (2, 14, 26, 38, ...) as a third group, and so on for a total of 12 groups.

Once the data has been trellis encoded, it is coupled to the sync multiplexer 170. The sync multiplexer 170 is a multiplexer which inserts the various synchronization signals (Data Segment Sync and Data Field Sync). A two-level (binary) 4-symbol Data Segment Sync is inserted into the 8-level digital data stream at the beginning of each Data Segment. The MPEG sync byte is replaced by Data Segment Sync. In an exemplary embodiment using ATSC transmission standards, a complete segment shall consist of 832 symbols: 4 symbols for Data Segment Sync, and 828 data plus parity symbols. The same sync pattern occurs regularly at 77.3 s intervals, and is the only signal repeating at this rate. Unlike the data, the four symbols for Data Segment Sync are not Reed-Solomon or trellis encoded, nor are they interleaved. The ATSC segment sync is a repetitive four symbol (one byte) pulse that is added to the front of the data segment and replaces the missing first byte (packet sync byte) of the original PEG-2 data packet. Correlation circuits in the 8-VSB receiver home in on the repetitive nature of the segment sync, which is easily contrasted against the background of completely random data. The recovered sync signal is used to generate the receiver clock and recover the data. Segment syncs are easily recoverable by the receiver because of their repetitive nature and extended duration. Accurate clock recovery can be had at noise and interference levels well above those where accurate data recovery is impossible allowing for quick data recovery during channel changes and other transient conditions.

After sync multiplexer 170, the signal is coupled to the pilot inserter 175 where a small DC shift is applied to the 8-VSB baseband signal causing a small residual carrier to appear at the zero frequency point of the resulting modulated spectrum. This ATSC pilot signal gives the RF PLL circuits in the 8-VSB receiver a signal to lock onto that is independent of the data being transmitted. The frequency of the pilot is the same as the suppressed-carrier frequency. This may be generated by a small (digital) DC level (1.25) added to every symbol (data and sync) of the digital baseband data plus sync signal (+I, +3, +5,+7). The power of the pilot is typically 11.3 dB below the average data signal power.

After the pilot signal is inserted, the data is coupled to a pre-equalization filter 180 and the 8 VSB modulator 185. The modulator amplitude modulates the 8 VSB baseband signal on an intermediate frequency (IF) carrier. With traditional amplitude modulation, a double sideband RF spectrum is generated around the carrier frequency, with each RF sideband being the mirror image of the other. This represents redundant information and one sideband can be discarded without any net information loss. In 8 VSB modulation, the VSB modulator receives the 10.76 Msymbols/s, 8-level trellis encoded composite data signal (pilot and sync added). The ATV system performance is based on a linear phase raised cosine Nyquist filter response in the concatenated transmitter and receiver. The 8 VSB modulated signal is the coupled to an RF upconverter 190, shifting the frequency of the 8 VSB signal to the television channel frequency. This broadcast ready signal is then coupled to the antenna 195.

Referring to FIG. 2, a block diagram of an embodiment of a portion of an exemplary mobile/handheld data stream 200 of the present disclosure is shown. 26 ATSC M H coded packets are grouped into 1 Data Block. In legacy ATSC transmission every Data Block typically has the same coding, although this is not physically required. Preamble blocks are two blocks long and have 52 coded. The very first MPEG packet following the Preamble block is a control packet that contains system information.

Following randomization and forward error correction processing, the data packets are formatted into Data Frames for transmission and Data Segment Sync and Data Field Sync are added.

The ATSC-M/H data stream 200 is made up of bursts having a Preamble block 210 followed by a predetermined number of Data Blocks 230 appropriate for the selected data rate mode. According to the exemplary embodiment, each Data Block 230 consists of 26 MPEG packets. Each Data Frame consists of two Data Fields, each containing 313 Data Segments. The first Data Segment of each Data Field is a unique synchronizing signal (Data Field Sync) and includes the training sequence used by the equalizer in the receiver. The remaining 312 Data Segments each carry the equivalent of the data from one 188-byte transport packet plus its associated FEC overhead. The actual data in each Data Segment comes from several transport packets because of data interleaving. Each Data Segment consists of 832 symbols. The first 4 symbols are transmitted in binary form and provide segment synchronization. This Data Segment Sync signal also represents the sync byte of the 188-byte MPEG-compatible transport packet. The remaining 828 symbols of each Data Segment carry data equivalent to the- remaining 187 bytes of a transport packet and its associated FEC overhead. These 828 symbols are transmitted as 8-level signals and therefore carry three bits per symbol. Thus, 828 x 3 = 2484 bits of data are carried in each Data Segment, which is the requirement to send a protected transport packet: The ATSC M/H data stream consists of a sequence of blocks, each block consisting of 26 packets of the legacy VSB A/53 system. The ATSC M/H data stream is made up of bursts of blocks that each burst has a Preamble block followed by Nb Data Blocks, where Nb is a system variable parameter and a function of the overall ATSC M/H data rate to be transmitted. Each Data Block is encoded at one of the defined ATSC M/H rate modes. This rate mode is applied to the entire Data Block. For each burst of blocks, the Data Blocks are delivered such that the highest coded FEC rates (i.e. the lowest fractional numbers) in the burst of blocks will be delivered earliest and the lowest coded FEC rates (i.e. the highest fractional numbers) will be delivered the latest such that starting from a Preamble block, any following Data Blocks will have equal or less robustness than the current Data Block. ATSC A/53 8VSB coded legacy Data Blocks of 26 packets can be placed at one or more block for legacy overlay operation.

An enhancement to the ATSC or ATSC M/H transmission protocols that may be especially advantageous to handheld or portable devices is the use of data packets of different coding within the same burst, such as, a Base layer transmitted at one code rate and enhanced layer transmitted at a higher rate. Under this scheme, a laptop, for example, would combine the two to show enhanced video, but a cellular telephone may only show the base layer. This is advantageous as devices which require more robust coding often have lower resolution displays. In an exemplary embodiment according to the present invention, the handheld data stream 200 comprising preamble blocks 210 and data blocks 230. Data blocks 0 and 1 may be coded at 1/4 for base layer and blocks 10 and 11 coded at 1/2 for enhanced layer. Thus different code rates are transmitted in the same burst.

Turning now to FIG. 3, a data frame 300 is shown according to the present invention is shown. The data frame 300 shown is organized for transmission where each Data Frame consists of two Data Fields, each containing 313 Data Segments. The first Data Segment of each Data Field is a unique synchronizing signal (Data Field Sync) and includes the training sequence used by the equalizer in the receiver. The remaining 312 Data Segments each carry the equivalent of the data from one 188-byte transport packet plus its associated FEC overhead. The actual data in each Data Segment comes from several transport packets because of data interleaving. Each Data Segment consists of 832 symbols. The first 4 symbols are transmitted in binary form and provide segment synchronization. This Data Segment Sync signal also represents the sync byte of the 188- byte MPEG-compatible transport packet. The remaining 828 symbols of each Data Segment carry data equivalent to the remaining 187 bytes of a transport packet and its associated FEC overhead. These 828 symbols are transmitted as 8-level signals and therefore carry three bits per symbol. Thus, 828 x 3 = 2484 bits of data are carried in each Data Segment, which exactly matches the requirement to send a protected transport packet:

187 data bytes + 20 RS parity bytes = 207 bytes

207 bytes x 8 bits/byte = 1656 bits

2/3 rate trellis coding requires 3/2 x 1656 bits = 2484 bits.

The exact symbol rate is given by equation 1 below:

(1) S_r (MHz) = 4.5/286 x 684 = 10.76... MHz

The frequency of a Data Segment is given in equation 2 below:

(2) f_seg= S_r / 832 = 12.94... X 10³ Data Segments/s.

The Data Frame rate is given by equation (3) below:

(3) fframe = W626 = 20.66 ... frames/s.

The symbol rate S_r and the transport rate T_r shall be locked to each other in frequency.

The 8-level symbols combined with the binary Data Segment Sync and Data Field Sync signals are used to suppressed-carrier modulate a single carrier. Before transmission, however, most of the lower sideband is removed. The resulting spectrum is flat, except for the band edges where a nominal square root raised cosine response results in 620 kHz transition regions. At the suppressed-carrier frequency, 310 kHz from the lower band edge, a small pilot is added to the signal as described previously.

Turning now to FIG. 4, a block diagram of an exemplary embodiment of a studio to transmitter link 400 is shown. The studio to transmitter link comprises a studio location 410 and a transmitter location 420 which may be co-located or located several kilometers apart for reasons described previously. The studio location 410 comprises a studio 415 or other content generation facility, an ATSC encoder 425, a standard definition encoder 440, an ATSC M/H encoder 450, a multiplexer 430 and a

reception/transmission means, such as a parabolic antenna 435 or the like. The transmitter location 420 comprises a reception/transmission means 455, such as a parabolic antenna, an exciter 460, distribution circuitry 475, a plurality of power amplifiers 480, a power supply 485, a high power combiner 490 a filter 495 a directional coupler 465 and a transmission tower with antenna 470.

The studio 415 is the source of the content to be broadcast. The content can originate from stored content, such as digital content or analog content, live simulcast content, such as live television programs, or retransmitted content such as sporting events recorded remotely and transmitted to the studio via a communications link other than the studio to transmitter link. This content is formatted at the studio for processing by an encoder before being transmitted to the transmitter.

The ATSC encoder 425 receives the content from the studio and encodes the content according to the Advanced Television Standards Committee (ATSC) digital transmission standard. For broadcast television, the ATSC standard requires an 8 VSB modulated signal. Video content may be encoded in many different image sizes and of differing resolutions. The reduced bandwidth requirements of lower resolution images facilitates the simultaneous broadcast of up to 6 sub-channels, each comprising different programs and possibly different resolutions. The ATSC encoder packetizes the content provided from the studio 415 in a manner described previously. The encoded ATSC content is then coupled to the multiplexer 430.

The standard definition (SD) encoder 440 receives the content from the studio and encodes this content according to the National Television System Committee (NTSC) analog transmission standard. An NTSC television channel as transmitted occupies a total bandwidth of 6 MHz which includes approximately 500 kHz upper and lower guard bands. The video carrier is centered at 1.25 MHz within the 6 MHz band and the croma, or color information, is 3.579545 MHz above the video carrier, and is quadrature-amplitude-modulated with a suppressed carrier. The main audio carrier is 4.5 MHz above the video carrier, making it 250 kHz below the top of the channel. The encoded SC content is then coupled to the multiplexer 430. The ATSC mobile handheld (M/H) encoder 450 receives the content from the studio and encodes this content according to the ATSC M/H standard. ATSC M/H is a service for mobile TV receivers and partly uses the 19.39 Mbit/s ATSC 8VSB stream. The encoded ATSC M/H data is then coupled to the multiplexer 430. The multiplexer 430 receives content from various encoders, such as the ATSC,

SD and ATSC M/H encoders shown in this exemplary embodiment. The multiplexer 430 is operative to time multiplex or frequency multiplex the various encoded signal into a transport stream for coupling to the transmitter 420. The transport stream may comprise MPEG compression and utilize an Asynchronous Serial Interface (ASI) streaming data format for carrying the MPEG Transport Stream. An ASI signal can carry one or multiple compressed SD, HD or audio programs at varying transmission speeds responsive to the studio requirements. The multiplexed data stream is then coupled to a transmission means, such as an RF parabolic antenna 435, fiber interface, or any other of a multitude of transmission mediums. Likewise, the signal is received at the transmitter location 420 by a similar transmission means, such as an RF parabolic antenna 455. According to an aspect of the present invention, the multiplexer 430 receives the ATSC M/H payload data and generates an ATSC M/H packet. The packet is constructed with transmitter control and synchronization information inserted in place of the packet identifier or in place of the training bits. Since these bits are known and mandated by the standard, the transmitter can recover the control data and insert the known data into the ATSC M/H packet, thereby reducing bandwidth consumption on the studio to transmitter link.

The received signal at the transmitter location 420 is coupled first to an exciter 460. The exciter is operative to apply the physical layer additions to the signal, such as RF modulation and error correction. Additionally, the exciter receives additional information from the multiplexer 430 such as synchronization information and control information. Synchronization information is used for timing offsets that might be set in the system. Timing offsets possibly related to signal frequency network operations or other modes of operations that might be signaled through the system. Synchronization information may provide synchronization of phase, frequency and modulation between an FM booster transmitter and the main transmitter. Control information is used by the studio location 410 to control performance and regulatory compliance of the transmitted signal. Signal strength, directional amplification, frequency and transmit bandwidth are among some of the signal characteristics controlled in response to the control information.

The modulated signal is then coupled from the exciter to a distribution circuit 475. The distribution circuit 475 distributes the modulated signal to a plurality of power amplifiers 480. The power amplifiers may separately amplify different signals or bands of signals. The amplified signals are then recombined in a high power combiner 490, which is band pass filtered by a filter 495. The filtered signal is then coupled to the transmission tower with antenna 470 via a directional coupler 465. The directional coupler 465 prevents received and reflected signals from coupling back into the transmission path. Turning now to FIG. 5, a block diagram 500 of an exemplary embodiment of an

ATSC M/H transport block 510 according to the present disclosure is shown. The ATSC M/H transport block 510, or packet, is the basic unit of data in a transport stream. The transport block comprises a transport header and payload. The header comprises a sync byte, followed by three one-bit flags and a 13-bit Packet Identifier (PID). This is followed by a 4-bit continuity counter, optional transport fields and payload, where the total packet length is 188 bytes. According to an aspect of the present invention, the PID for the ATSC M/H packets is known to the exciter, so these packets can be processed differently than the ATSC packets. The three one bit flags and the continuity counter can be calculated by the exciter independent of information provided by the multiplexer. Therefore, other information, such as control and synchronization information can be placed at these locations by the multiplexer 430, extracted by the exciter 460 and then the transport header can be calculated and placed in the packet in place of the extracted information. The would result in 1 18 bytes per ATSC M/H block available as an information pipe from the multiplexer 430 to the exciter 460.

Turning now to FIG. 6 a block diagram 600 of another exemplary embodiment of an ATSC M/H transport block according to the present disclosure is shown. In this embodiment of the present invention, synchronization and control information is placed by the multiplexer in known training byte locations. These locations are dictated by the ATSC M/H A/153 standard and are filled with known sequences. Similar to the previous embodiment, the multiplexer 430 can insert synchronization data and control data in the training byte locations, this data can be extracted by the exciter 460, and the known training byte sequences substituted for the extracted data by the exciter 460. This substitution would facilitate a very high bandwidth channel from the multiplexer to the exciter of up to 2143 bytes per ATSC M/H block. FIG. 7 is a state diagram of an exemplary embodiment of a method of transmitting data 700 in a studio to transmitter link according to the present invention. The method of transmitting data 700 is performed primarily by an exciter 460 located at the transmitter location 420. The exciter 460 receives 710 an ATSC M/H packet from the studio to transmitter link. The exciter 460 then extracts control information 720 from the received packet where the control information is located in a position within the packet normally occupied by known data called for in the ATSC A/153 standard, such as training data or the PID. Equipment located at the transmitter location 420 is controlled in response to the extracted data 730. The exciter then replaces the extracted data in the ATSC M/H packets with the known data as called from the in ATSC A/153 standard 740. The exciter 460 then couples the data to the additional transmission circuitry.

Fig. 8 is a state diagram of another exemplary embodiment of a method of transmitting data in a studio to transmitter link 800 according to the present invention. This exemplary embodiment of a method of transmitting data 800 is performed primarily by the multiplexer 430. The multiplexer receives the ATSC M/H payload 810 from the ATSC M/H encoder 450. The multiplexer 430 then structures the data into ATSC M/H blocks or packets. According to an exemplary embodiment of the present invention, the multiplexer 430 places control and/or synchronization information in the bit positions reserved for packet identification or training bit data 820. The multiplexer 430 then transmits the packet to the studio to transmitter link.

While the present invention has been described in terms of a specific

embodiment, it will be appreciated that modifications may be made which will fall within the scope of the invention. For example, various processing steps may be implemented separately or combined, and may be implemented in general purpose or dedicated data processing hardware. Furthermore, various encoding or compression methods may be employed for video, audio, image, text, or other types of data. Also, the packet sizes, rate modes, block coding, and other information processing parameters may be varied in different embodiments of the invention.

Claims

1. An apparatus for communication comprising:

- an encoder for encoding television program data and generating an encoded television program data;

- a multiplexer for receiving said encoded television program data and generating a packet wherein said packet comprises said encoded television program data and transmitter control data; and

- a link for coupling said packet to a transmitter.

2. The apparatus of claim 1 wherein said packet is an ATSC M/H transport packet.

3. The apparatus of claim 1 wherein said control data is inserted in said packet in a position reserved for a packet identifier.

4. The apparatus of claim 1 wherein said control data is inserted in said packet in a position reserved for training data.

5. The apparatus of claim 1 wherein said transmitter control data comprises

synchronization data.

6. A method of communication comprising the steps of:

- receiving encoded television program data;

generating a packet comprising said encoded television data and transmitter control information; and

- transmitting said packet to a transmitter.

7. The method of claim 6 wherein said packet is an ATSC M/H packet.

8. The method of claim 6 wherein said transmitter control data is inserted in said packet in a position reserved for a packet identifier.

9. The method of claim 6 wherein said transmitter control data is inserted in said packet in a position reserved for training data.

10. The method of claim 6 wherein said transmitter control information comprises synchronization data.

11. A transmitter for transmitting a television signal: - An exciter for receiving a packet comprising television program data and control data, said exciter further operative to extract said control data and replace said control data within said packet with standard data;

- a transmitter for transmitting said packet comprising said television

program data and said standard data; and

- a controller for controlling said transmitter in response to said control data.

12. The apparatus of claim 11 wherein said packet is an ATSC M/H transport packet.

13. The apparatus of claim 1 1 wherein said exciter replaces said control data with a packet identifier.

14. The apparatus of claim 1 1 wherein said exciter replaces said control data with training data.

15. The apparatus of claim 1 1 wherein said control data comprises synchronization data.

16. A method of communication comprising the steps of:

- receiving an encoded packet comprising control data and encoded

television data;

- extracting said control data from said encoded packet;

generating a transmission packet comprising said encoded television data and standard data wherein said standard data replaces said control data in said encoded packet; and

- transmitting said transmission packet to a transmitter.

17. The method of claim 16 wherein said encoded packet is an ATSC M/H packet.

18. The method of claim 16 wherein said control data is inserted in said encoded packet in a position reserved for a packet identifier.

19. The method of claim 16 wherein said control data is inserted in said encoded packet in a position reserved for training data.

20. The method of claim 16 wherein said transmitter control information comprises synchronization data.