Abstract:
Mobile/handheld (M/H) data is received in an M/H frame equivalent in size to exactly 20 VSB data frames. Each VSB frame contains an odd VSB field and an even VSB field, and each of the VSB fields includes one field sync segment and 312 data segments. The M/H frame includes main data and M/H data, and the M/H data has more robust coding than the main data. The M/H frame is received and an MPEG encoded transport stream derived therefrom is outputted. Frame registration is found so as to find a structure of the M/H frame in the MPEG encoded transport stream. Based on the structure of the M/H frame, the M/H data is randomized. Based on the structure of the M/H frame, block mode data is located within the randomized M/H data. The M/H data is decoded using the block mode data.

Description:
RELATED APPLICATION 
       [0001]    The present application contains disclosure similar to disclosure contained in application (7290). 
       TECHNICAL FIELD 
       [0002]    Data analyzing such as might be used to verify proper operation of a transmitter and combined main/mobile receiving such as might be used to receive both main data and mobile data under the ATSC A/153 part 2 Standard are described herein. 
       BACKGROUND 
       [0003]    The ATSC transmission scheme set out in the ATSC A/53 Standard involves the use of 8-VSB modulation in transmitting terrestrial and cable broadcasts for digital television receivers. An ATSC A/53 field (an ATSC A/53 frame has an odd field and an even field) contains a field sync segment and 312 data segments each beginning with a segment sync. The data segments also include main data. ATSC A/53 is optimized for fixed reception. 
         [0004]    Unfortunately, transmissions according to this standard are not robust enough against doppler shift and multipath radio interference in mobile environments because it is designed for slowly varying signal conditions. In order to provide robust reception in spite of doppler shifts and multipath radio interference in mobile environments, additional channel coding mechanisms are introduced in the ATSC a/153 Standard to protect the signal. 
         [0005]    The A/153 Standard describes the ATSC Mobile DTV system referred to in the Standard as the ATSC mobile/handheld (M/H) system. The M/H system provides mobile/pedestrian/handheld broadcasting services using a portion of the ATSC 8-VSB payload, while the remainder is still available for HD and/or multiple SD television services. The M/H system is a dual-stream system that includes the ATSC service multiplex for existing digital television services and the M/H service multiplex for one or more mobile, pedestrian and handheld services. 
         [0006]    Thus, the ATSC A/153 Standard known as ATSC-M/H is a standard for mobile digital televisions that allows television broadcasts to be received by mobile devices. ATSC-M/H is an extension to the available digital TV broadcasting standard ATSC A/53. 
         [0007]    According to Part 2 of the A/153 Standard, one M/H Frame can carry main data (processed in accordance with the A/53 Standard) and M/H data (processed in accordance with the A/153 Standard) and is equivalent in size to exactly 20 VSB data frames. The M/H Frame consists of five consecutive Sub-Frames such that each Sub-Frame contains the same amount of data as four VSB data frames or eight A/53 data fields. Each Sub-Frame consists of sixteen consecutive M/H Slots. Each M/H Slot consists of 156 transport stream packets or equivalently 156 data segments at the symbol level, i.e., equivalent to one half of a A/53 data field. A particular Slot may contain M/H data, a combination of M/H data and main data, or only main data. If an M/H Group is transmitted during an M/H Slot, then the first 118 transport stream packets in the Slot belong to an M/H Group, and the remaining 38 packets are main data packets. If there is no M/H Group in an M/H Slot, the M/H Slot contain 156 main data packets. As in the case of an A/53 field, an A/153 field has a field sync segment and each data segment includes a segment sync portion. 
         [0008]    There is no method to verify that all of the M/H data is properly placed in the frame. Current receivers output decoded data or decoded FIC (Fast Information Channel) data. TPC (Transmission Parameter Channel) data is available on a sub-sampled register basis. However, it is not presently possible to verify training signals, M/H RS (Reed Solomon) data, CRC (Cyclic Redundancy Check) data, and/or M/H TP (Transport Packet) header data. Similarly, it has not been possible to check every instance of TPC data or the proper placement and values of FIC data. For debugging, it is important to have the raw data stream to verify the robust coders and proper parameter signaling. 
         [0009]    Thus, there has been confusion among transmitter manufacturers as they try to create M/H modulators. 
         [0010]    Accordingly, it is desirable to have available a data analyzer that verifies training signals, M/H RS (Reed Solomon) data, CRC (Cyclic Redundancy Check) data, and/or M/H TP header data as well as every instance of TPC data and/or the proper placement and values of FIC data in M/H transmitters. 
         [0011]    Moreover, the only option for both main and mobile reception has been the use of two separate receivers, one for main data and one for M/H data. 
         [0012]    The ATSC Mobile/Handheld service (M/H) shares the same RF channel as a standard ATSC broadcast service described in ATSC A/53 , also known as the “Main service.” Hence, main data is data ordinarily transmitted in accordance with the ATSC A/53 standard. M/H data is data that receives extra coding to give the data more robustness than main data. This extra coding conforms to the ATSC A/153 Standard. 
         [0013]    Accordingly, it is desirable to have available a single receiver that receivers both main and mobile data. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a block diagram of a data analyzer that is capable of analyzing M/H data; and, 
           [0015]      FIG. 2  is a block diagram of a combined Main and Mobile receiver. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    As shown in  FIG. 1 , a data analyzer  10  has a receiver  12  that receives and demodulates the VSB television signal supplied by a VSB transmitter. The receiver  12 , for example, may be a receiver manufactured according to the ATSC Digital Televisions Standard A/53. 
         [0017]    As such, the output of the receiver  12  is an MPEG transport stream. 
         [0018]    The MPEG transport stream from the receiver  12  is provided to a processor  14  such as a post-processor. The processor  14  includes a frame registration find block  16 , a randomization block  18 , a training sequence, FIC, and TPC block  20 , an M/H decode block  22 , and a data select block  24 . The processor  14 , for example, may be one or more elements of a computer. The computer for example, may include memory, one or more input devices such as a mouse and/or a keyboard, one or more output devices such as a display and/or a printer, one or more processing elements such as a microprocessor, etc. In this case, the blocks of the processor  14 , for example, may be blocks of code executed by the processor  14 . Alternatively, each of the blocks of the processor  14  or various combinations of the blocks of the processor  14  may be hardware and/or firmware such as ASICs or other ICs. 
         [0019]    The frame registration find block  16  finds the frame registration (i.e., location or structure of the frame) in the MPEG transport stream provided by the receiver  12 . Finding frame registration enables the processor  14  to find the location of the mobile data whose value and position in the transport stream frames is to be verified to ensure proper operation of the transmitter. The frame registration find block  16  may find the frame registration in a number of ways. 
         [0020]    For example, the frame registration find block  16  may locate the training sequence in the MPEG transport stream provided by the receiver  12 . The location of the training sequence in the MPEG transport stream provided by the receiver  12  is predetermined even though the MPEG transport stream provided by the receiver  12  is deinterleaved by the receiver  12 . Because the training sequence has a predetermined location in the frame, the frame structure within the MPEG transport stream provided by the receiver  12  is easily determined. 
         [0021]    Alternatively, if the receiver  12  is configured to provide an output corresponding to the frame sync of a frame, the frame registration find block  16  can use the frame sync to easily find the frame structure within the MPEG transport stream provided by the receiver  12 . 
         [0022]    As another alternative, the frame registration find block  16  can find the PID that identifies the packets containing mobile data. Because the mobile data has predetermined locations within the frame, the frame registration find block  16  can use the mobile PID to easily locate the frame structure within the MPEG transport stream provided by the receiver  12 . 
         [0023]    Once the frame structure is located within the MPEG transport stream provided by the receiver  12 , the M/H data in the located frame structure is randomized by the randomization block  18 . The receiver  12 , as one its final processing steps, derandomizes the transport stream. However, the transmitter does not randomize the mobile (M/H) data that it transmits. Therefore, the mobile data in the transport stream provided by the receiver  12  is not correctly represented. Accordingly, the randomization block  18  reverses the derandomization of the mobile data performed by the receiver  12  and returns the mobile data to its correct representation. The randomization block  18  is a byte scrambler. At this point, the processor  14  now knows where some of the MH data is, although the value of this data is not known. 
         [0024]    Because the location of the frame structure is determined by the frame registration find block  16  and because the mobile data is returned to its correct representation by the randomization block  18 , the training sequence, FIC, and TPC block  20  is able to locate and strip the training sequence, the FIC data, and the TPC data from the transport stream. The FIC data essentially indicates the service locations in the MH Frame, and the TPC data provides a map that indicates where the main and mobile data are packed into the frame. The TPC data also indicates the SCCC (Series Concatenated Convolutional Code) block mode. The training sequence is useful in training the equalizer of a receiver. 
         [0025]    The TPC basically indicates to the processor  14  where the M/H data is and how to decode it. The FIC indicates to the processor  14  where the programs are in the mobile parades and may repeat several times per frame. However, because neither the TPC nor the FIC is actual program data, they are not included in any output stream.) 
         [0026]    One M/H Block of data can constitute a single SCCC Block or two M/H Blocks of data can constitute a single SCCC Block. The SCCC Block Mode identifies the relationship between the M/H Block and the SCCC block. If the SCCC Block Mode is equal to ‘00’ (separate), then each SCCC Block consists of a single M/H Block. If the SCCC Block Mode is ‘01’ (paired), then two M/H Blocks constitute a single SCCC Block. 
         [0027]    The M/H decode block  22  uses the SCCC block mode to determine the relationship between the M/H blocks and the SCCC blocks in order to decode the M/H data using the SCCC. The M/H decode block  22  may also be arranged to perform the functions specified in A/153 part 2, section 5.3.2 to 5.3.2.6. The data select block  24  selects the M/H payload to be verified. 
         [0028]    The M/H data to be verified generally includes the TPC data, the FIC data, the RS (Reed Solomon) Blocks, and/or the training sequence. Current receive chips output decoded data and decoded FIC data. TPC data is available on a sub-sampled basis. However, it has not been possible to verify the training sequence, M/H RS data, CRC data, and M/H TP header data. Similarly, it has not been possible to verify every instance of TPC data or the proper value and placement of FIC data. For debugging purposes, it is important to have available the raw data stream so that the robust coders and parameter signaling of the transmitter can be verified. The data select block  24  outputs this raw data stream so that the robust coders and parameter signaling of the transmitter can be verified. 
         [0029]    Thus, the data select block  24  selects all of the data in the raw data stream provided by the M/H decode block  22 . Alternatively, the data select block  24  can select a sub-set of the data available in the raw data stream provided by the M/H decode block  22 . For example, it may not be desired to verify the Reed Solomon and CRC data. If this is the case, the data select block  24  need not select this data. Also, the M/H decode block need not decode the non-selected data. 
         [0030]    An analyzer  26  analyzes the selected data provided by the data select block  24  to determine if the selected data has been properly placed in the frame. 
         [0031]    As shown in  FIG. 2 , a combined main/mobile receiver  30  is arranged to receive both main data (data that has not received the robust extra coding that the mobile data receives) and mobile data (data that has received the robust extra coding). Previously, separate main and mobile receivers were necessary to receive both main and mobile data. 
         [0032]    The combined main/mobile receiver  30 , for example, includes the same receiver and processor as in  FIG. 1  and, hence, the same reference numerals are used to designate common elements. Accordingly, the combined main/mobile receiver  30  includes the receiver  12  and the processor  14  of  FIG. 1 . Also, the processor  14  includes the frame registration find block  16 , the randomization block  18 , the training sequence, FIC, and TPC block  20 , the M/H decode block  22 , and a data select block  24 . 
         [0033]    For main reception, the MPEG-2 transport packet output of the receiver  12  is provided to an MPEG-2 decoder  32  that uses the decoding specified in the ATSC A/53 Standard to decode the main data and that provides the MPEG-2 decoded data to a television monitor  34 . Packets not relevant to the chosen program (such as mobile data) are ignored. For M/H reception, the data select block  24  selects and provides the M/H data to an MPEG-4 decoder  36  that uses the decoding specified in the ATSC A/153 Standard to decode the M/H data and that provides the MPEG-4 decoded data to the television monitor  34 . In this way, the user of the television monitor  34  has the option of displaying main data or M/H data on the same television monitor and does not need separate receivers to be able to receive both main and M/H data. 
         [0034]    (Both the mobile receiver and the main receiver have a CPU to process the table data (PSIP) to determine what data in the stream is relevant to the current program. The stream entering the MPEG-2 decoder is not scrambled or coded, it is the MPEG-2 transport stream.) 
         [0035]    Certain modifications of the present invention have been discussed above. Other modifications of the present invention will occur to those practicing in the art of the present invention. 
         [0036]    Accordingly, the description of the present invention is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which are within the scope of the appended claims is reserved.