JP2005510141A - Use of digital TV broadcast signals to provide GPS support information - Google Patents

Abstract

  To a satellite positioning system receiver (1502) configured to determine the position of a satellite positioning system receiver using satellite positioning system support information (1522) and a propagation time of a signal transmitted by a satellite of the satellite positioning system. A method and apparatus for providing satellite positioning system support information and a computer readable medium (FIG. 15) provide satellite positioning system support information (1522), and a digital television comprising a plurality of frames, each frame comprising a plurality of data segments. Providing a signal (1506), encoding satellite positioning system support information as a cipher word, replacing a data segment in the digital TV signal with a cipher word, and transmitting the digital TV signal, where satellite positioning The system receiver receives digital TV signals and supports satellite positioning system support information. Play.

Description

Cross-reference of related applications

  This application is a non-provisional US application Ser. No. 10 / 003,128 entitled “Digital Broadcast Television Signals” filed on November 14, 2001 by Jimmy K. Ohmura, James J. Spirker Jr. and Matthew Rabinowitz. Robust Data Transmission Utilized ", a continuation-in-part application, US Provisional Patent Application No. 60 / 281,269" Mobile Reception "filed April 3, 2001 by James J. Spielker and Matthew Rabinowitz Claims the benefit of the "ATSC standard DTV channel for low data rate broadcast to the machine", the disclosure of which is hereby incorporated by reference in its entirety.

  No. 10 / 159,478 “Global Positioning Signal Amplified by Television Broadcasting Signal” filed May 31, 2002 by Matthew Rabinowitz and James J. Spirker Jr. Is a continuation-in-part application of US non-provisional patent application No. 09 / 887,158 filed June 21, 2001 by James J. Spielker and Matthew Rabinowitz, “Digital US Provisional Patent Application No. 60 / 361,762, filed March 4, 2002 by James J. Spielker, “Expanded by GPS”. DTV positioning ”and US provisional patent filed on February 1, 2002 by James J. Spielker Application No. 60 / 353,440 “DTV positioning expanded by GPS” and US Provisional Patent Application No. 60 / 332,504 filed Nov. 13, 2001 “DTV Amplified GPS for Robust Airplane Navigation” The disclosure of which is hereby incorporated by reference in its entirety.

  This application is based on US Provisional Patent Application No. 60 / 281,269, filed April 3, 2001 by James J. Spielker and Matthew Rabinowitz "ATSC standard DTV channel for low data rate broadcast to mobile receivers. The disclosure of which is hereby incorporated by reference in its entirety.

  This application is based on US non-provisional patent application No. 09 / 932,010 “Positioning Using Terrestrial Digital Video Broadcasting Television Signals” filed on August 17, 2001 by James J. Spielker and Matthew Rabinowitz. ”And US Provisional Patent Application No. 60 / 337,834,“ Radio Positioning Using Japanese ISDB-T Digital Television Signals, ”filed on November 9, 2001 by James J. Spielker. The disclosure of which is hereby incorporated by reference in its entirety.

  The present invention generally relates to data transmission via digital broadcast television signals, for example, digital television signals are in accordance with the American Television Standards Committee (ATSC) format, which allows the transmission of Global Positioning System (GPS) assistance information and Especially relevant.

  Beginning with the first ATSC standard digital television broadcast in the late 1990s, digital television broadcast is rapidly spreading in the United States. By the end of 2000, over 166 digital television transmitters are in operation. The FCC has set a goal: by 2006 all television broadcasts are on recently assigned digital channels and analog channels are returned to the government for other applications.

  The availability of sophisticated data compression techniques and increased digital signal processing capabilities allows high quality audio image information to be transmitted with the same bandwidth as analog channels. In the television broadcasting community, the Advanced Television Standards Committee (ATSC) creates both digital and high-definition television standards and takes advantage of these technological advances. These standards are often referred to as ATSC digital television or simply ATSC. The current ATSC standard uses an amplitude modulated suppressed carrier residual sideband modulation technique called VSB. 8-VSB modulation is used in terrestrial “off-air” broadcast systems, and 16-VSB modulation is proposed for higher data rate cable systems.

  These standards are optimized for broadcasting television programs. However, the rapid development of digital television broadcasting and the corresponding expansion of digital television transmitters create opportunities for transmission of other data types. Examples of other data types include data that allows a mobile phone to calculate its own location without the need for external processing, short messages, applications similar to pager messages, stock quotes, text formats Web page, simple grid map showing places of interest near mobile phones, TV program guides, radio program guides, bus timetables, store advertisements near receivers, and all types of low data rate mobile commerce information including.

  Television infrastructure is not necessarily suitable for these types of data. For example, the ATSC standard is adapted to a certain spectral efficiency, meaning that a certain amount of information should be transmitted over a certain spectral bandwidth. In particular, the bit rate must be high enough to support the broadcast of television programs and fit in the bandwidth allocated for a single television channel. With this operating condition, a certain signal-to-noise ratio is required to successfully receive broadcast signals. For example, a 19.2 Mbps ATSC standard broadcast data rate requires a receiver with a theoretical signal-to-noise ratio of 15 dB.

  However, other operating points can be more suitable for other types of data. For example, low data rate applications can benefit from lower spectral efficiency but more robust transmission. This type of signal can be played with a much lower signal-to-noise ratio than is necessary to receive digital television broadcasts, thereby distant areas, indoors, where interference and multipath cause problems Reception is possible. In addition, simpler receivers can be used compared to those required to receive digital television broadcasts.

  Thus, there is a need for a system and method that can take advantage of the rapidly developing digital television (DTV) structure infrastructure except for data transmission other than television programs. In particular, more robust and slower data rate transmissions are of interest.

Summary of the Invention

  In general, in one aspect, the invention features a method and apparatus for providing satellite positioning system assistance information to a satellite positioning system receiver and a computer readable medium, the satellite positioning system receiver comprising satellite positioning system assistance information and The satellite positioning system is configured to determine a position of the satellite positioning system using a propagation time of a signal transmitted by the satellite. It provides satellite positioning system support information, provides a digital television signal comprising a plurality of frames, each frame consists of a plurality of data segments, encodes satellite positioning system support information as a cipher word, and a data segment in the digital television signal Is replaced with a cipher word and a digital television signal is transmitted. Here, the satellite positioning system receiver receives the digital television signal and reproduces the satellite positioning system support information.

  Particular embodiments can include one or more of the following features. The satellite positioning system is a global positioning system (GPS). The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information. The satellite positioning system support information includes at least one group of satellite positioning system satellite positions, clock correction information for satellite positioning system satellites, Doppler information for signals transmitted by the satellite positioning system satellites, and satellite positioning system satellites. It consists of information on the influence of the atmosphere on the transmitted signal and the identification of the satellite positioning system satellite visible to the satellite positioning system receiver. Digital television signals are at least one group of American Television Standards Committee (ATSC) digital television signals, European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signals, and Japanese terrestrial digital. And an integrated broadcasting service (ISDB-T) signal.

  In general, in one aspect, a method and apparatus for reproducing satellite positioning system assistance information from a digital television signal and a computer readable medium are characterized. It receives a digital television signal, the digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments, wherein at least one data segment represents at least satellite positioning system assistance information. It is replaced by one cipher word, and the data segment replaced by the cipher word is selected, and the satellite positioning system support information is reproduced from the selected data segment.

  Particular embodiments can include one or more of the following features. The satellite positioning system is a global positioning system (GPS). The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information. The satellite positioning system support information includes at least one group of satellite positioning system satellite positions, clock correction information for the satellite positioning system satellites, Doppler information for signals transmitted by the satellite positioning system satellites, and satellite positioning system satellites. Information on the influence of the atmosphere on the signal transmitted by the satellite and the identification of the satellite positioning system satellite visible to the satellite positioning system receiver. Digital television signals are at least one group of American Television Standards Committee (ATSC) digital television signals, European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signals, and Japanese terrestrial digital integration. It consists of a broadcast service (ISDB-T) signal.

  In general, in one aspect, the invention features a method and apparatus for determining the position of a satellite positioning system receiver utilizing a satellite positioning system and a computer readable medium. A satellite positioning system receiver receives a signal transmitted by a satellite of a satellite positioning system, a digital television signal composed of a plurality of frames is received by a satellite positioning system receiver, and each frame is derived from a plurality of data segments. And at least one data segment is replaced by at least one cipher word representing satellite positioning system support information, selecting the data segment replaced by the cipher word, and satellite positioning system support from the selected data segment It consists of reproducing the information and determining the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information.

  Particular embodiments can include one or more of the following features. The satellite positioning system is a global positioning system (GPS). The satellite positioning system support information is transmitted by at least one group of satellite positioning system satellite positions, clock correction information for satellite positioning system satellites, Doppler information for signals transmitted by satellite positioning system satellites, and satellite positioning system satellites. Information on the influence of the atmosphere on the received signal and identification of the satellite positioning system satellite visible to the satellite positioning system receiver. Digital television signals are at least one group of American Television Standards Committee (ATSC) digital television signals, European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signals, and Japanese terrestrial digital integration. It consists of a broadcast service (ISDB-T) signal. An embodiment determines a pseudorange between a satellite positioning system receiver and a transmitter of a digital television signal based on a known component of the digital television signal; and the pseudorange and a signal received from a satellite positioning system satellite; And determining the position of the satellite positioning system receiver based on the satellite positioning system support information. In accordance with the present invention, digital data is transmitted as part of a digital television (DTV) broadcast signal by encoding the digital data as a cipher word and replacing some data segments of the DTV signal with the cipher word. The use of long cipher words results in a more robust transmission than part of the DTV broadcast signal used for television programs and can therefore be received with a lower signal-to-noise ratio. Using a limited set of cipher words allows digital data to be reproduced using a simple one-bank correlator at the receiver.

  In general, in one aspect, the invention features an apparatus for providing satellite positioning system assistance information to a satellite positioning system receiver, the receiver including satellite positioning system assistance information and signals transmitted by satellites in the satellite positioning system. And a position of the satellite positioning system receiver is determined using the propagation time of. A second satellite positioning system receiver that receives satellite positioning system support information, a channel coder that provides a digital television signal composed of a plurality of frames each of which consists of a plurality of data segments, and satellite positioning system support information as cipher words It consists of an encoder that encodes, a packet multiplexer that replaces data segments in the digital television signal with cipher words, and a transmitter that transmits the digital television signal, where the satellite positioning system receiver receives the digital television signal, Play satellite positioning system support information.

  Particular implementations can include one or more of the following features. The satellite positioning system is a global positioning system (GPS). The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information. The satellite positioning system support information is transmitted by at least one group of satellite positioning system satellite positions, clock correction information for satellite positioning system satellites, Doppler information for signals transmitted by satellite positioning system satellites, and satellite positioning system satellites. Information on the influence of the atmosphere on the received signal and identification of the satellite positioning system satellite visible to the satellite positioning system receiver. Digital television signals are at least one group of American Television Standards Committee (ATSC) digital television signals, European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signals, and Japanese Terrestrial Digital Integrated Broadcasting. Service (ISDB-T) signal.

  In general, in one aspect, the invention features an apparatus for reproducing satellite positioning system assistance information from a digital television signal. It consists of a front end and a back end, the front end receiving a digital television signal, the digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments, wherein at least one The data segment is replaced by at least one cipher word representing the satellite positioning system support information, and the back end selects the data segment replaced by the cipher word and reproduces the satellite positioning system support information from the selected data segment. .

  Particular implementations can include one or more of the following features. The satellite positioning system is a global positioning system (GPS). The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information. Satellite positioning system support information includes at least one group, clock correction information for satellite positioning system satellites, Doppler information for signals transmitted by satellite positioning system satellites, and atmospheric effects on signals transmitted by satellite positioning system satellites. And information on the satellite positioning system satellite visible to the satellite positioning system receiver. Digital television signals include the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB-T). ) Comprises at least one group of signals.

  In general, in one aspect, the invention features an apparatus for determining the position of a satellite positioning system receiver utilizing a satellite positioning system. It consists of a front end, a back end, and a processor, which receives a signal transmitted by a satellite of a satellite positioning system and receives a digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments. Where at least one data segment is replaced by at least one cipher word representing satellite positioning system assistance information, and the back end selects a data segment replaced by the cipher word and satellites from the selected data segment The positioning system support information is reproduced, and the processor determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information.

  Particular implementations can include one or more of the following features. The satellite positioning system is a global positioning system (GPS). The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information. Satellite positioning system support information includes satellite positioning system satellite position, clock correction information for satellite positioning system satellites, Doppler information for signals transmitted by satellite positioning system satellites, and atmosphere to signals transmitted by satellite positioning system satellites. And at least one of the group consisting of identification of satellite positioning system satellites visible to the satellite positioning system receiver. Digital television signals are the American Television Standards Committee (ATSC) digital television signals, European Telecommunications Standards Institute (ETSI) digital video broadcasting-terrestrial (DVB-T) signals, and Japan Terrestrial Digital Integrated Broadcasting Service (ISDB-T). At least one of the group consisting of signals. The processor determines a pseudorange between the satellite positioning system receiver and the digital television signal transmitter based on a known component of the digital television signal, and determines the pseudorange and the signal received from the satellite positioning system satellite and the satellite positioning system. The position of the satellite positioning system receiver is determined based on the assistance information.

  The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

Detailed Description of the Invention

  As used herein, the terms “client” and “server” generally refer to an electronic device or mechanism, and the term “mechanism” refers to hardware, software, or any combination thereof. Is mentioned. These terms are used to simplify the description that follows. The clients, servers, and mechanisms described herein can be implemented on any general purpose computer or as a specific device.

Transmission Data Using DTV Signals FIG. 1 is a block diagram of an example system 100 according to the present invention. The system 100 includes a receiver 102 that receives digital television (DTV) broadcasts from one or more DTV transmitters 106A-N.

  One example of a DTV transmitter 106 is a transmission tower that broadcasts DTV signals to the receiver 102 via air. Another example is a transmitter for a cable television system, where the DTV signal reaches the receiver 102 via a cable line. Satellite television systems are also known as direct broadcast satellites (DBS) and are another example of digital television broadcast systems. For example, Ecostar and Direct TV are major DBS services in the US market. Generally speaking, there are currently three basic types of commercial digital television broadcast systems. Terrestrial, cable, and satellite. Satellite television systems are all digital, while cable and terrestrial systems are converting from their mostly analog predecessors to digital. These digital television systems use a frame structure composed of encoded data packets. These data packets are also referred to as data segments.

  The receiver 102 is meant to refer to any object that can implement the low data rate channels described below. In addition, the receiver 102 can receive television program data conveyed by a DTV signal, but this is not required. The receiver 102 may be stationary and / or movable. Virtually, any object that can include a chip or software that implements the robust low data rate channel described below can be the receiver 102. Thus, DTV televisions, pagers, mobile phones, PDAs, computers, cars, and other vehicles are all examples of receivers 102 when properly equipped.

  In system 100, DTV transmitter 106 transmits digital data to receiver 102 at a data rate significantly less than broadcast television program data. Robust low data rate digital data is written to the DTV signal broadcast on transmitter 106. The DTV signal is received by the receiver 102 and the digital data is reproduced from the DTV signal.

  For example, in some applications, the digital data is a local street map showing places of interest near the mobile phone. Other applications allow the mobile phone to calculate its own location without requiring external processing, applications similar to short messages, pager messages, stock quotes, and news headlines And TV program guides, radio program guides, bus timetables, store short text advertisements at the receiver location, and all types of low data rate mobile commerce information. Based on today's technology, most digital data for these applications consists of short text and / or simple graphs, eg representing maps. Many data broadcast applications can have a low data rate version. For example, Wireless Application Protocol (WAP), a current generation mobile data technology that reformats web pages to fit very small wireless monitors, was introduced in 1999. The simpler text-only version is an example of an application for a robust low data rate system using DTV signals.

  FIG. 2 is a representative example of the structure of an ATSC frame from the current ATSC standard. The current ATSC signal was described on March 16, 2000 by the Advanced Television System Committee in “ATSC Digital Television Standards and Correction No. 1” and is hereby incorporated by reference in its entirety. The terrestrial broadcasting ATSC signal uses 8-sequence residual sideband modulation (8-VSB). The symbol rate of the ATSC signal is 10.76 MHz and is derived from the 27.00 MHz clock. An ATSC frame structure 200 is illustrated in FIG. Frame 200 includes a total of 626 segments, each having 828 symbols. Each segment is followed by four symbols used for synchronization purposes. These will be referred to as segment synchronization attachments. In FIG. 2, time progresses from right to left. There are a total of 520,832 symbols per frame. Each segment (and the corresponding segment sync attachment) lasts 77.3 microseconds. The first and 314th segments in each frame are field synchronization segments. Each field sync segment below is a 312 data segment.

  Each field sync segment is one of two fixed known 828 symbol sequences. The two 828 symbol sequences differ only in the extent to which 63 symbol sections are inverted in one sequence compared to the other. Some other symbols in these field sync segments are different for each transmitter. One of these two known field sync segments is transmitted every 24.2 milliseconds. These symbol sequences are included as training sequences to help the ATSC receiver correct for the multipath found by way of example in the broadcast channel. A field sync segment is considered a spread spectrum cipher and can be obscured by an ATSC data sequence. The spread spectrum cipherword is detected by a correlator by way of example (eg, a matching filter). If a multipath signal of an ATSC broadcast signal is present at the receiver, the output of such a correlator can give an estimate of the parameters of the multipath signal. Since field sync segments appear once every 24.2 milliseconds, they can be used to provide periodic fragments of multipath signals. For dynamically changing multipath signals, the multipath characteristics of the provisional period can be estimated using conventional methods such as blind equalization or other interpolation schemes.

  A data segment is a place where television program data is transmitted. Each data segment corresponds to a 188 byte data packet in the MPEG2 transport layer. Each 188 byte data packet is expanded to 828 3 bit coded data symbols using a combination of Reed-Solomon encoder, interleaver, and rate 2/3 trellis encoder. Also, the data segment may be used to convey other information, such as web content from the Internet, or may not be used when the data segment is said to contain zero packets.

  The segment synchronization attachment is the same for all segments. It consists of four symbol sequences (-1, 1, 1, -1) and is used for segment synchronization by way of example.

  Embodiments of the present invention can be expanded to use future enhancements to DTV signals. For example, the ATSC signal specification enables high-speed 16-VSB signals primarily for digital cable television. However, the 16-VSB signal has the same general frame structure as the 8-VSB signal and uses field sync segments and data segments. Therefore, extending the 8-VSB example shown below to a 16-VSB signal is a straightforward approach.

  The 8-VSB signal is constructed by filtering. The in-phase segment of the symbol pulse has a raised cosine characteristic and is described in JG Proxies' digital communication, McGraw-Hill 3rd edition (1995). The pulse can be expressed as:

ここで、Ｔはシンボル周期であって、

Where T is the symbol period and

β＝０．５７６２である。この信号は振動数特性を有し、

β = 0.5762. This signal has frequency characteristics,

それによって、信号の片側帯域幅が（１＋β）１０．７６２２３ＭＨｚ＝５．３８ＭＨｚ＋０．３１ＭＨｚであると見ることができる。この同相パルスからＶＳＢ信号を創出するために、信号はフィルタリングされ、低側波帯の小さい部分のみが残る。このフィルタリングは以下のように表され、

Thereby, it can be seen that the one-sided bandwidth of the signal is (1 + β) 10.76223 MHz = 5.38 MHz + 0.31 MHz. To create a VSB signal from this in-phase pulse, the signal is filtered, leaving only a small portion of the low sideband. This filtering is expressed as follows:

ここで、

here,

Ｈα（ｆ）は低側波帯の残留リマインダーを残すよう設計されたフィルターである。このフィルターはＨ_α（−ｆ）＝−Ｈ_α（ｆ）とＨ_α（ｆ）=０，ｆ＞αという特性を満たす。そのレスポンスＵ（ｆ）Ｐ（ｆ）は以下のように表され、

Hα (f) is a filter designed to leave a low sideband residual reminder. This filter satisfies the characteristics of H _α (−f) = − H _α (f), H _α (f) = 0, and f> α. The response U (f) P (f) is expressed as follows:

ここで、

here,

はＰ（ｆ）のヒルバート変換である。ＶＳＢパルスは次の式で表され、

Is the Hilbert transform of P (f). The VSB pulse is expressed by the following equation:

ベースバンドパルス信号は、

The baseband pulse signal is

であって、ここでＰ_νｉ（ｔ）は同相成分であって、Ｐ_νｑ（ｔ）は直交成分である。

Where P _νi (t) is an in-phase component and P _νq (t) is a quadrature component.

  Before the data is transmitted, the ATSC signal also incorporates the carrier signal and has a power that is -11.5 dB lower than the data signal. This carrier wave is useful for coherent demodulation of the signal. As a result, the transmitted signal can be expressed as:

ここで、Ｃｎは８レベルデータ信号である。

Here, Cn is an 8-level data signal.

  FIG. 3 is a flowchart illustrating a method 300 for transmitting digital data using an ATSC frame 200. In general, some data segments are replaced by cipher words representing the transmitted digital data. More specifically, the transmitted digital data is encoded as a cipher word (310). The cipherword replaces the data segment in the DTV signal (320). The DTV transmitter 106 broadcasts a DTV signal including a cipher word (330). The receiver 102 receives the broadcast signal (340), from which digital data is reproduced (350).

  Consider first a simple example where one data segment of each frame is replaced by one of two possible cipher words, each 828 symbols long. In other words, each cipherword is the same length as the data segment. One cipher word represents binary 0 and the other represents binary 1. The two cipher words are preferably orthogonal to each other. In this simple example, one bit of data can be transmitted every ATSC frame for a data rate of approximately 21 bits per second (bps).

If the two cipherwords are orthogonal, a simple incoherent receiver has the same performance as normal incoherent reception of a binary frequency shift coded signal. Thus, with an ideal white Gaussian noise channel model, the bit error probability is given by
_{P b = 0.5exp {-E b /} 2N 0} (11)
Here, N ₀ is a two-phase noise spectral density, and E _b is an energy per bit. In this case, _Eb for the single bit transmitted is the energy at the receiver for all 828 symbol segments. It is equal to the television transmitter power at the receiver multiplied by the segment duration of 77.3 microseconds. Therefore, _Eb is 29 dB greater than the energy for each DTV broadcast symbol.

  As a result, digital data can be recovered from broadcast signals and is much weaker than can accept television reception. For example, signals that are 30 to 40 dB weaker than those required for receiving digital television signals are suitable for use with these low data rate channels. In turn, this allows digital data to be played over a much wider range than typical DTV coverage. In addition, this low data rate channel can be received at many indoor locations where television broadcast reception is difficult.

  Another advantage of this approach is that reception of low data rate signals can be done with a much simpler receiver than the reference DTV receiver and will be discussed in more detail below. For this type of data transmission, simple incoherent energy detection of cipher words using a correlator at the receiver is appropriate. This type of receiver is simple in design, small in size and low in energy consumption.

  Another advantage is that no significant expense is required to implement the transmitter and will be discussed in more detail below. Many DTV transmitters already include broadcast station reference equipment that replaces individual segments with DTV signals. This equipment can be used to replace certain segments with field sync segments or replace the resulting MPEG zero packets, for example, because there is no television program data to transmit at the transmission times of these data segments. is there. To implement the required transmitter functionality, this equipment need only be modified to replace certain data segments with alternative cipher words.

The simple example above produces a data rate of about 20 bps. The data rate can be increased in a number of ways. For example, more than one bit can be conveyed by a data segment of 828 symbols each replaced with a frame. In one approach, more than two cipher words are used. For example, incoming digital data can be divided into bit sequences, each 3 bits long. Each of these bit sequences is encoded as a cipherword selected from a set of eight possible 828 symbol cipherwords. Each of the eight cipher words corresponds to one of eight possible 3-bit sequences. The eight cipher words are preferably orthogonal to each other to facilitate reception. According to the 3-bit sequence, one of the eight cipher words is written to the DTV signal, replacing the corresponding data segment in the frame, which is shown in FIG. 4A. Here, the data rate is currently about 62 bps. In the notation used, a cipher word is represented by Cn, and the notation [C ₀ ,... C _N-1 ] represents one cipher word selected from a set of N cipher words. By way of example, one cipher word selected from a finite set of N cipher words is used to replace the data segment. If N = 8, the cipherword represents one of eight possible 3-bit sequences. A check table can be used to convert from a 3 bit sequence to the corresponding cipher word. In this example generalization, 2 ^ N cipher words can be used to replace a bit sequence that is N bits long.

  In general, the set of cipherwords should be selected to have good correlation properties that minimize reception errors. In addition to being orthogonal, the cipherword should have low time-shift cross-correlation and small side lobes with autocorrelation functions. In general, cipher words based on multiple amplitude symbols will yield better correlation characteristics than cipher words based on binary amplitude symbols. Such cipher word sets have been extensively studied in various applications, particularly in spread spectrum communication systems. The most popular commercial application is the code division multiple access (CDMA) system used in the United States in the IS-95 cellular standard. Since the 8-VSB ATSC standard is based on 8-level modulation, cipher words using multiple amplitude symbols can be suitable for this standard. More specifically, 4-level or 8-level symbols can be used in place of binary (2-level) symbols. Also, possible cipher word sets can include cipher words that do not represent a bit sequence. For example, a 3-bit sequence can be represented by a set of nine cipher words, where the ninth cipher word represents “no data present”.

  In an alternate form, multiple cipherwords can be used to replace a single data segment. As shown in FIG. 4B, another way to perform three bits per data segment is to subdivide the data segment into three sub-segments, each of 828/3 = 276 symbols long. Each of these subsegments is used to represent one bit and is replaced by one of the two possible 276 symbol cipher words. If one data segment per frame is replaced by a set of three such cipher words, the data rate is about 62 bps.

  The reverse is also possible. In other words, a single cipher word can occupy more than one data segment. For example, when a more robust transmission is desired, one 3 × 828 = 2484 symbol cipher word is used and one of the two cipher words replaces three data segments, which is shown in FIG. 4C.

  Other alternatives will be apparent. In FIG. 4A, the digital data was divided into bit sequences, all of which were the same length. In another approach, the digital data is divided into bit sequences of varying length, and each bit sequence is decrypted into a corresponding cipher word. In addition, the cipherword can change length. Not all 828 symbol data segments need to be replaced by cipher words. For example, 5 bits per data segment can be encoded as five 160 symbol ciphers, for a total of 800 symbols per data segment, as shown in FIG. 4D. However, this approach is generally not preferred because the current technology is easy to process DTV signals on segments on a segment basis, and the approach of FIG. 4D is the remaining 28 symbols in the data segment. To spend effectively. In general, however, cipher words will have a data rate that is much lower than the data rate they replace by example. Generally speaking, the number of bits per cipherword increases, making a robust low data rate receiver more complex and reducing its performance.

  Also, the overall data rate can be increased by increasing the number of data segments per frame used for the low data rate channel. Under the current ATSC standard, all data segments are used to transmit television programs and the resulting DTV signal has a data rate of about 19.2 Mbps. Current television signals do not require this large bandwidth by way of example. For example, HDTV typically requires about 12-15 Mbps, and standard definition television requires about 3-5 Mbps by example. This remains at either 20-80% of the total capacity not to be used. If 20% of the total capacity is used for the low data rate channel, 125 data segments per data frame will be used for this channel. If 5 bits are coded in each data segment, the overall data rate would be about 12.5 Kbps. By doing this, about 4 Mbps television programs are replaced by a low data rate channel of 12.5 Kbps, but the low data rate channel is much more robust and takes a longer range using simpler receiver technology. Can be received across.

  Also, the selection of which data segments should be replaced and how many data segments should be replaced can be implemented in many ways. A straightforward approach is to replace a preselected data segment. For example, in FIG. 5A, data segments 10-50 of each frame are dedicated to low data rate channels, and these are data segments that are replaced by cipher words. In this case, the receiver can be further simplified. The receiver knows a priori that only data segment 10-50 can contain cipher words. It is therefore sufficient to test the data segment against these cipher words. Furthermore, if a cipherword is always present in these data segments, it is sufficient for the receiver to determine which of the possible cipherwords is most likely to be transmitted. In other words, if there are 8 possible cipher words (eg representing different 3 bit sequences), it is sufficient for the receiver to determine which of the 8 cipher words were transmitted in the received data segment interval. is there. There is no need to determine whether a cipherword exists.

  In an alternative approach, data segments are replaced by cipher words on the basis of such improvements if possible. For example, the transmitter can determine whether a data segment contains data packets or zero packets. That is, the transmitter determines whether the data segment is used or not used. If it contains data, the data segment is not used for the low data rate channel. Only unused data segments are referred to by example as “zero packets” and are replaced by cipher words. In FIG. 5B, data segment 600-624 of frame 1 is not used and is replaced by a cipher word. In the next frame, data segments 533-597 are not used and are replaced by cipher words. In this case, the receiver may not know a priori which data segments contain the cipher words. Using the correlation threshold, the receiver must first estimate which data segments contain ciphertext.

  Also, these two approaches can be combined. For example, data segments 10-50 may be dedicated to the low data rate channel, and any other unused data segment may be available for the low data rate channel.

  FIG. 6 is a block diagram of the DTV transmitter 106. The transmitter 106 includes the following elements: a data compression engine 610, a data multiplexer 620, a channel coder 630, a packet multiplexer 640, an 8-VSB modulator and a transmitter (for field sync segments, segment sync attachments and ciphertext). 650 and transmitter tower 660 are connected in series. Transmitter 106 also includes a data encoder 670 that is coupled to packet multiplexer 640.

  The transmitter 106 operates as follows. The analog television signal is compressed by the compression engine 610. MPEG2 is a data compression standard used by the current ATSC standard. This approach allows broadcasters to transmit television signals at data rates from typical 3 Mbps to 15 Mbps depending on the desired reception quality. In FIG. 6, other data entering data multiplexer 620 can include television signals in digital form, in which case there may not be an analog television signal entering 610.

  Since the standard 6 MHz bandwidth of a single analog television channel can transmit 19.2 Mbps using the ATSC digital format, converting to digital is an extra capacity to transmit other data to the broadcaster. Provides uniform multiple TV channels for every 6 MHz channel. Data multiplexer 620 combines multiple streams of data into a single ATSC signal. Examples of other types of data include other television programs already in digital form and program guide information. Since the data is packetized on the DTV broadcast signal, any type of digital data can be transmitted on the television program channel at 19.2 Mbps. There has been a proposal to send a video rich form of internet web traffic on such television program channels.

  Channel coder 630 encodes the resulting data packet and corrects channel errors. In the normal approach, channel coder 630 implements a combination of Reed-Solomon error correction encoding and interleaver and trellis encoding.

  The ATSC standard for terrestrial broadcasting uses 8-VSB modulation in the form of 8 levels of amplitude with 3 bit symbols. After channel coding, the coded data of 8 level symbols is divided into data segments.

  The packet multiplexer 640 is a device that can replace data on a segment according to segment criteria. The sequence of 8 level symbols is sent to the 8-VSB modulator and transmitter 650. The modulator 650 applies 8-VSB modulation. Transmitter 650 broadcasts the resulting DTV signal through transmitter tower 660.

  For the low data rate channel, the data encoder 670 generates a ciphertext from the incoming digital data. For example, the data encoder 670 can convert a bit sequence into a ciphertext using a check table. For applications that are not real-time, both the incoming bit sequence and / or the outgoing ciphertext are stored and continuously retrieved from memory.

  As an example, in the case of a 3-bit sequence that is translated into 828 symbol cipher words, the data encoder 670 divides incoming digital data into 3-bit sequences and translates them into the corresponding cipher words. In one embodiment, this is done by a check table with a 3-bit input and outputs the corresponding cipher word. The cipherword from the data encoder 670 is written into the ATSC frame at the transport layer by the packet multiplexer 640. Writing a cipher word is very similar to writing a field sync segment, except that the actual data written is different. Since the packet multiplexer 640 almost certainly writes the field sync segment, it is straightforward to modify the existing packet multiplexer 640 and write the cipherword.

  In one physical embodiment, blocks 610-640 are implemented as equipment located at a television broadcast station. The modulator and transmitter 650 are located very close to the tower 660, such as the tower base. Other embodiments are obvious. For example, some or all of the blocks 610-640 may be located at other physical locations, particularly if the television program is not live. In this case, the pre-recorded program can be processed at different locations.

  7-12 illustrate various aspects of the receiver 102. FIG. The receiver 102 reproduces digital data from an encrypted word embedded in the broadcast DTV signal. FIG. 7 is a block diagram of the front end 400 used in the receiver 102. Sampler 400 takes a sample of the received DTV signal. In the approach shown in FIG. 7, the DTV broadcast signal 402 is received by the antenna 404. This is followed by a filter and amplifier 406. The filtered and amplified DTV broadcast signal is converted into a square baseband signal having the same phase by the local oscillator 416, the mixer 418I, and the low-pass filters 410I and 410Q. More specifically, the DTV broadcast signal is divided into two. Each mixer 408I, 408Q multiplies the sine or cosine component of the local oscillator 416 by one of the DTV broadcast signals. Each multiplied signal is low pass filtered by a filter 410I or 410Q, respectively, to produce baseband I and Q components of the received DTV broadcast signal. This is sampled and quantized by an analog-to-digital converter (ADC) 412. Digital samples of the ADC baseband I and Q outputs can be stored in a later processing memory and processed immediately by a digital processor or enter a digital circuit that performs the digital processing in hardware. FIG. 7 is a typical front end for a receiver. In particular, FIG. 7 may be a front end of a conventional DTV receiver that receives television program data. Other types of front ends will be obvious.

FIG. 8 is a block diagram of a back end used in the receiver 102. The back end 800 receives digital I and Q samples from the receiver front end. For convenience, the I and Q samples are indicated by a single line in FIG. The back end 800 includes a bank of correlators 805A-805N, with one correlator 805 for each possible cipherword. FIG. 8 illustrates the general case where there are N possible cipher words and N corresponding correlators 805. Each correlator 805 correlates the incoming sample with the corresponding template for the cipher word. In one embodiment, the template is a cipher match filter. Therefore, the data segment to be output test of the correlation unit 805A provides a measure of the possibility of including an encryption word C _0. Similarly, correlation measures the likelihood of such cipher words C _1. A bank of correlators 805 are coupled to a comparator 810 to determine which correlation is the largest. The data bits of the selected cipher word are output. For example, when producing the strongest correlation is a correlation machine 805B, a bit sequence corresponding to the encryption word C ₁ is reproduced by the receiver.

  Multipath is common on wireless channels. At the receiver, the multipath signal is a multiple copy of each signal transmitted with different delays. This produces a correlator output, with multiple correlation peaks of various sizes corresponding to the transmitted cipherwords. The receiver can take advantage of multipath, combining all multipaths associated with the correlation peaks from each cipherword correlator and comparing among all such cipherword correlators. This receiver performs better than a conventional receiver and only sees the correlator output at a particular moment. This type of receiver can be implemented by changing the criteria for comparison in comparator 810.

  The correlator 805 shown in FIG. 8 can be implemented in many different ways. FIG. 9 shows an example of the correlator 900. I samples from the front end enter the tap delay line 910I, and Q samples from the front end enter the tap delay line 910Q. The cipherword determines which samples are multiplied and added by devices 920I and 920Q on tap delay lines 910I and 910Q. Tap delay line 910 is long enough to store samples for all cipher words (eg, all data segments when there is a one-to-one replacement of data segments with cipher words). At each sample time, new I and Q samples from ADC 412 enter tap delay lines 910I and 910Q. Parallel outputs from tap delay lines 910I and 910Q flow to multiply and add devices 920I and 920Q, respectively. The outputs of these devices are squared by squaring devices 507I and 507Q and added again by an adder 508. Thus, the correlator 900 generates an output at the same sample time. In one form of back end 800 of FIG. 8, correlator 900 of FIG. 9 is repeated N times and performed once for each correlator 805 of FIG. Multiply and adder circuits (920I and 920Q) change for each correlator 805, thereby performing correlation for different templates.

  FIG. 10 illustrates another type of correlator 500 and can be used in FIG. This is a serial correlator. The I and Q samples from the front end are multiplied by mixers 504I and 504Q, respectively, for the I and Q components of code generator 502 and are uniquely determined by the cipherword. The code generator 502 is synchronized with the arrival time of the samples received by the back end. The I and Q samples to be multiplied are added by adders 506I and 506Q. Sums are calculated at cipherword time intervals (eg, with one data segment if there is a one-to-one permutation of data segments with cipherwords). These sums are squared by squaring devices 507I and 507Q and added together by adder 508. Correlator 500 generates one output for all correlations. That is, the correlator 500 generates a correlation function at a specific moment (in a case where a correlation peak is expected, for example). In contrast, the correlator 900 of FIG. 9 generates samples of the correlation function at different times. In the form of the back end 800 of FIG. 8, the correlator 500 of FIG. 10 is repeated N times, once for each of the correlators 805 of FIG. Different cipherword templates are generated by changing the code generator 502.

  In another form, the back end of the receiver 102 is implemented by a programmed digital signal processor that performs the required correlation.

  FIG. 11 is a flowchart illustrating a method of reproducing digital data by constructing the framing of an incoming ATSC signal. Receiver 102 constructs the framing by identifying (1210) the field sync segment in the ATSC frame. This is accomplished, for example, using the correlator 900 of FIG. 9, where the multiply and add devices 920I and 920Q are designed to perform correlation on the field sync segment. Building framing simplifies continuous data reproduction, where individual data segments can be identified, and the temporary location of the cipherwords will be known by the receiver 102. If framing is not established, the receiver must detect the cipherword and does not know the beginning and end positions of each cipherword at the receiver 102. This is more complex, but could be achieved by taking into account unknown timing, for example by using correlation and collation filtering, but for the case where the cipherword is received by the receiver.

  More particularly, recall that a field sync segment occurs once every 313 segments (or once every 24.4 milliseconds) in the ATSC format of FIG. Initially, a continuous stream of symbols is received by the receiver 102. It is not known where the data segment begins and ends, nor does it know which data segment is a field sync segment. Both of these ambiguities are removed to build the framing.

  FIG. 12 is a block diagram of a device 1200 that removes this ambiguity. The device 1200 includes a back end 800 and will play digital data as soon as framing is established. The remainder of device 1200 includes the following connected in series. A correlator 900, a bank counter 1210, and a comparator 1220. These elements are used to identify field sync segments. Counter 1250 is used to synchronize backend 800. The block diagram is functional. Various embodiments with the same functionality will be apparent.

  The framing function of device 1200 operates as follows. The incoming symbol stream is arbitrarily divided into 24.2 millisecond blocks and further divided into 313 intervals of 77.3 microseconds each. The 24.2 millisecond block corresponding to the ATSC half frame and the 77.3 microsecond interval correspond to the data segment. In other words, the field sync segment occurs once during each 24.2 millisecond block, and the field sync segment lasts for a time interval of 77.3 microseconds (but the beginning and end of the data segment is unknown) So it spans two adjacent 77.3 microsecond boundaries).

  Correlator 900 correlates the incoming 77.3 microsecond time interval for the “generic” field sync segment. The template is “generic” in a sense, and the correlator 900 detects 757 symbols, which is normal for all field sync segments (recall that some symbols vary between different field sync segments). ). Correlator 900 has an output for each sample time. That is, it outputs a correlation function sampled at many different points in time. This is useful because the exact location of the correlation peak is not yet known.

  In the counter 1210 bank, one counter is assigned to each of 313 time intervals. During each time interval, the correlator output samples are compared to a threshold. If the output of the correlator 900 exceeds the threshold, the time interval counter 1210 is incremented. This is repeated, with the counter 1210 forming a repeating cycle, with each 313 interval appearing once every 24.4 milliseconds. Accordingly, each counter 1210 counts the number of times, and each 313th time interval (for example, the first, 314th, 627th, etc. time interval for counter 1 and the second, 315th, 628 for counter 2). Time intervals, etc.) exceed the threshold. Over time, the counter 1210 with the highest count will be the one corresponding to the field sync segment. Comparator 1220 determines which count is the largest, thereby identifying the field sync segment. The beginning of the field sync segment cannot be accurately determined by the counter 1210 bank alone, but the comparator limits the position of the field sync segment within 77.3 milliseconds. The exact position of the starting point of the field sync segment can be determined based on the precise structure output from the correlator 900.

Noise at the receiver front end 102 is assumed to be a white Gaussian noise with dual spectral density N _0. By spacing in some noise does not include the field sync segment, the output sample is the sum of the squares of two independent Gaussian random variables with variance of N _0/2, respectively. The probability that this sample X exceeds the threshold value T is expressed by the following equation.

P (T) = Pr {X> T} = exp {−T / N ₀ } (12)
Expected value of X is E {X} = _{N 0.} If the threshold is set at 3 times, this average is T = 3N ₀ , then
P (3N ₀ ) = 0.05 (13)
Is the probability that this noise sample will exceed the threshold and produce an increasing counter.

  In the second time interval, there are more than 40 decisions for each of the 313 counters. If the signal ratio at the receiver is greater than −22 dB, the counter should quickly indicate which of the 313 intervals contains FSS. This gives a 6-7 dB FSS correlator output with a processing gain of about 29 dB, which is stronger than the noise background of the correlator output.

  There are many ways in which the correlator output can be used to determine the position of the field sync segment. In one example, the bank counter 1210 is replaced by a bank of accumulators. The peak correlation for each of the 313 intervals is integrated to produce a partial sum of 313. That is, the integrator 1 integrates the peak correlation with respect to the first, 314th, and 627th intervals. The largest partial sum of many correlations will be one corresponding to the field sync segment.

  Once the field sync segment is identified, the time gate delay lock loop can be used to maintain lock on the multipath component of the received broadcast signal field sync segment. These incoherent combinations of the delay locked loop outputs can be made to improve processing gain.

  Once framing is established, individual data segments can be identified and tested against the cipherword. In the example of FIG. 11, it is assumed that a data segment is preselected for the low data rate channel. The numerical position of the data segment is then determined (1220) and the previously selected data segment is processed for the ciphertext. For example, if data segment 10-50 is preselected for the low data rate channel, receiver 102 need only count up to segment 10 for the field sync segment and process segment 10-50 for the cipherword. To do.

  Referring again to FIG. 12, assume that time interval # 137 has been identified as a field sync segment. Counter 1250 counts up to data segments 10-50 with respect to field sync segments, and these data segments will be processed by backend 800.

  If the transmitter is to write a cipher word into the segment when there is an opportunity, the receiver does not know if the data segment contains the cipher word. As a result, after the receiver has established framing, each data segment is processed by a bank of correlators, for example as shown in FIG. Comparator 810 selects the most probable cipher word based on the correlation strength, but there is another decision as to whether all cipher words have been transmitted. In one approach, this determination is based on all correlator outputs. An example determines that no cipherword was present when there was no highest peak correlator output among all correlator outputs. This is based on the fact that if a cipherword is transmitted during this interval, the correlator output for the transmitted cipherword has a high probability that it has a much larger correlator output peak than at other cipherword correlator outputs. ing. As an example, the largest correlator output peak is at least twice the corresponding correlator output peak of other correlator output peak values for a decision that a cipherword is transmitted at a specific segment interval. Is required.

  In another form, the functionality shown in FIG. 12 is implemented in a DSP processor.

  Although the present invention has been described in considerable detail with respect to certain preferred forms thereof, other forms are possible. For example, some examples have been described using specific frequencies such as IF and baseband. This does not mean that these examples are limited to these specific frequencies. In general, different embodiments can be operated at different frequencies. Similarly, the various steps can be implemented as either analog or digital processing. As another example, processing of an incoming DTV signal can occur either without storing the incoming signal in real time or by retrieving a sample of the DTV signal from memory. As a final example, different types of templates can be used to achieve the desired correlation.

  In the ATSC standard, field sync segments use binary amplitude symbols, while transmitter 8-VSB modulated signals typically allow up to 8 levels of amplitude. Typically, a cipher word will be selected to use 2-level, 4-level, and 8-level amplitudes in the cipher symbol sequence. If more levels of symbols are used for a cipher word, there are more cipher word choices with good autocorrelation and cross-correlation properties, thus improving cipher word detection at the receiver 102. However, more levels make the correlator at the receiver 102 more complex.

  In another form, DTV signals other than ATSC signals can be used. All DTV signals depend on data segments organized in frames. The cipherword can replace some of these data segments, resulting in a robust and low data rate transmission unless the replacement degrades the remaining DTV signal in an unacceptable manner. For example, data segments in the DTV format are encoded independently, and replacing one data segment does not affect the decoding of other data segments, and data segments are individually Can be substituted. Preferably the data segment is replaced at the transport layer, but this is not required.

Transmission of GPS assistance information using DTV signals Originally devised in 1974, the Global Positioning System (GPS) is widely used for location, navigation, surveys, and time transfer. The GPS system uses a group of 24 orbiting satellites in a sub-synchronous 12 hour orbit. Each satellite maintains a precision clock and transmits a pseudo-noise signal, and the GPS receiver can be accurately tracked to determine the pseudo-range between the GPS receiver and the GPS satellite. By tracking four or more satellites, the receiver can determine a three-dimensional accurate position in real time around the world. For example, more details can be found in BW Parkinson and JJ Spirker Jr., "Global Positioning System-Theory and Applications", Volume 1, AAAA, Washington, DC (1996).

  GPS has revolutionized navigation and positioning technology. However, in some cases, the effectiveness of GPS has been reduced. This is because GPS signals are transmitted over long distances at relatively low power levels (less than 100 watts), and reception strength is relatively weak (approximately -160 dBw received by an omnidirectional antenna). Therefore, the signal is slightly useful or not useful in the presence of obstructions or in buildings. At these moments, the accuracy of the GPS location can be significantly or completely reduced.

  However, GPS positioning is aided by data transmission, making GPS more robust against attenuation and multipath. Examples of this type of data include clock correction information based on the current position of the GPS satellite and atomic standards. Another example includes information about the Earth's atmosphere, including Doppler information and ionospheric effects that alter or disturb satellite signals. Another example includes a list of satellites that are visible given the location of a given user, the spatial coordinate data of those selected satellites, and the predicted Doppler data of those selected satellites. The example also includes data that is modulated into a C / A GPS code signal. This data also includes information to assist the device in tracking and determining the exact distance to the GPS satellite. These types of data are referred to herein as GPS assistance information.

  The device can use this low data rate GPS assistance information and integrate GPS satellite signals more efficiently and / or with longer time periods by conventional well-known techniques. These techniques are commonly referred to as assist GPS, aid GPS, or A-GPS. Devices using GPS assistance information are more robust to attenuation caused by obstacles, and further GPS assistance information allows these devices to obtain a significantly attenuated GPS signal from far below the noise floor To do. As a result, GPS positioning can be improved by using this GPS assistance information especially when the GPS pseudo noise signal is attenuated.

  In addition, GPS receivers usually determine their position by calculating the relative arrival times of signals transmitted simultaneously from a very large number of GPS (or NAVSTAR) satellites. These satellites transmit both satellite positioning data, so-called “astronomical” data and clock timing data as part of the message. This information is transmitted on a channel that broadcasts at 50 bps. In other words, the device can receive GPS assistance information directly from the GPS satellite itself. However, the process of finding and capturing GPS signals, reading astronomical calendar data for a large number of satellites, and calculating the position of the device from this data is time consuming and often requires several minutes. In many cases, this very long processing time is unacceptable and further limits battery life in portable applications. This processing time also makes it very difficult to perform real-time position adjustments for applications that require a fixed position update, such as a real-time electronic street map of a car.

  In a preferred form, the GPS assistance information is transmitted to the end user device via a digital television (DTV) broadcast signal. For example, GPS assistance information requires only a low data rate by way of example. Therefore, the above technique is very suitable for spreading GPS support information via DTV broadcast signals. The advantage of this approach is that this communication channel is fairly robust. Compared to many other types of communication channels, the DTV-based communication channels described above can be reproduced with a lower signal-to-noise ratio, for example in remote areas or where interference or multipath causes problems. Thanks to the GPS assistance information, the GPS receiver can scan the available GPS signals more effectively. Also, for assistance information, the GPS receiver makes it easier to find GPS signals below the noise floor. In other forms, DTV signals consisting of GPS assistance information are spread by other means, both wired and wireless.

  FIG. 13 illustrates a system 1300 that includes one GPS receiver 1302 and a plurality of GPS satellites 1320A, 1320B, and 1320N according to one embodiment. FIG. 14 shows a process 1400 performed by a system 1300 according to an example embodiment.

  The DTV transmitter 1306 provides GPS support information (step 1402). In some embodiments, one or more monitoring stations 1308 receive GPS signals transmitted by GPS satellites 1320. Monitor station 1308 uses the received GPS signals to determine Doppler and astronomical calendar information for these satellites using conventional techniques. This GPS support information is transmitted to the retransmission credit DTV transmitter 1306 to the GPS receiver 1302.

  The DTV transmitter 1306 provides a digital television signal composed of a plurality of frames (step 1404). Each frame consists of a plurality of data segments. With the above technique, the DTV transmitter 1306 encodes GPS assistance information as an encrypted word (step 1406) and replaces the data segment in the digital television signal with the encrypted word (step 1408). The DTV transmitter 1306 transmits a digital television signal 1310 composed of GPS support information (step 1410).

  With the above technique, the GPS receiver 1302 receives the digital television signal 1310 (step 1412) and reproduces the GPS support information (step 1414). According to the prior art, the GPS receiver 1302 receives the signal transmitted by the GPS satellite 1320 (step 1416) and calculates the position of the GPS receiver 1302 using the GPS assistance information and the signal transmitted by the GPS satellite. (Step 1418).

  In another form, the approach described above is used in a navigation system other than GPS and uses a group of earth orbiting satellites that have a known location and generate a pseudo-random noise type signal to the receiver. Here, the Doppler correction signal propagation time is measured and the user position and velocity are calculated.

  FIG. 15 illustrates a system 1500 that includes only a GPS receiver 1502 and a single GPS satellite 1520 according to one embodiment. Of course, a single GPS satellite 1520 alone is not sufficient for position determination. Also, in this form, the GPS receiver 1502 uses pseudoranges to one or more DTV transmitters 1506 in position determination.

  FIG. 16 illustrates a process 1600 performed by a system 1500 according to an example embodiment. The DTV transmitter 1506 provides GPS support information (step 1602). In one embodiment, one or more monitoring stations 1508 receive GPS signals transmitted by GPS satellites 1520. Monitor station 1508 uses the received GPS signal to determine Doppler and astronomical calendar information for the satellite using conventional techniques. This GPS support information is transmitted to a DTV transmitter 1506 that is retransmitted to the GPS receiver 1502.

  The DTV transmitter 1506 provides a digital television signal composed of a plurality of frames (step 1604). Each frame comprises a plurality of data segments. In accordance with the above technique, the DTV transmitter 1506 encodes the GPS assistance information as an encrypted word (step 1606) and replaces the data segment in the digital television signal with the encrypted word (step 1608). The DTV transmitter 1506 transmits a digital television signal 1510 composed of GPS support information (step 1610).

  In accordance with the above technique, GPS receiver 1502 receives digital television signal 1510 (step 1612) and reproduces GPS assistance information (step 1614). The GPS receiver 1502 receives the signal transmitted by the GPS satellite 1520 (step 1616). The GPS receiver 1502 determines a pseudorange between the GPS receiver 1502 and the DTV transmitter 1506 based on the known components of the digital television signal transmitted by the DTV transmitter 1506 (step 1618). The GPS receiver 1502 calculates the position of the GPS receiver 1502 using the GPS support information, the signal transmitted by the GPS satellite 1520, and the pseudo distance between the GPS receiver 1502 and the DTV transmitter 1506 (step 1620). ).

  United States Television Standards Committee (ATSC) US terminal provisioning technology using digital television (DTV) signals is a US non-provisional patent application filed June 21, 2001 by James J. Spielker and Matthew Rabinowitz No. 09 / 887,158 “Positioning Using Digital Broadcast Television Signals” is disclosed in a publicly owned copending application, the disclosure of which is hereby incorporated by reference in its entirety. The European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal location technology was introduced by James J. Spielker Jr. and Matthew Rabinowitz on August 17, 2001. No. 09 / 932,010 filed in commonly owned co-pending application of “Positioning Using Terrestrial Digital Video Broadcasting Television Signal”, the disclosure of which is hereby incorporated by reference in its entirety . A technique for determining the position of a user terminal using the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB-T) signal is disclosed in US Patent Application No. 60/337 filed Nov. 9, 2001 by James J. Spielker. No. 834, “Radio Positioning Using Japanese ISDB-T Digital Television Signal”, the disclosure of which is hereby incorporated by reference in its entirety.

  Each of these television signals contains known components that can be used to obtain a pseudorange to the transmitter of the television signal. Appropriate components in the ATSC digital television signal include a synchronization code, such as a field sync segment in the ATSC data frame, and an intra-data segment sync segment in the ATSC data frame. Suitable components in ETSI DVB-T and ISDB-T digital television signals include distributed pilot carriers.

  The GPS receiver 1502 calculates the position of the GPS receiver 1502 using the DTV pseudorange, the GPS support information, and the signal transmitted by the GPS satellite 1520 (step 1620). A technique for positioning using DTV and GPS signals is disclosed in US Non-Provisional Patent Application No. 10 / 159,478, filed May 31, 2002 by Matthew Rabinowitz and James J. Spirker Jr. A publicly owned co-pending application “Positioning Using Global Positioning Signals Amplified by Broadcast Signals”, the disclosure of which is hereby incorporated by reference in its entirety. GPS receiver 1502 position calculations may include calculations using information representing the phase center (eg, position) of each DTV transmitter 1506 provided by database 1512 and weather information provided by weather information server 1514. And can be executed by either the GPS receiver 1502 or the separate location information server 1522. Data may be relayed between the GPS receiver 1502 and the location information server 1504 using the radio base station 1504 or otherwise.

  Of course, using only a single DTV signal and a single GPS signal is not sufficient to determine a three-dimensional position. Another signal, such as a second GPS signal or a second DTV signal, can be used as the third signal. Other GPS and / or DTV signals can be used as well.

  In another form, the above approach is used in navigation systems other than GPS, using a group of earth orbiting satellites having a known location and generating a pseudorange random noise type signal at the receiver, Here, the Doppler correction signal propagation time is measured to calculate the user position and velocity.

  Other signals within the digital television signal can be used to transmit GPS assistance information. For example, the Advanced Television System Committee (ATSC) is currently considering a new standard based on a working draft titled “Synchronous Standard for Distributed Transmission”. This proposed standard is for adding a transmitter that reaches the television receiver and can be cut off from the main transmitter. It describes a technique that allows the construction of a single frequency network (SFN) utilizing a very large number of transmitters.

  This proposed standard allows an SFN transmitter to transmit an identification signal, sometimes referred to as an “embedded identification signal” or “watermark”. These identification signals allow the transmitter to be uniquely identified, allowing system monitoring and measurement.

  The identification signal carries a scissors code binary sequence and is repeatedly transmitted for as long as transmission from the associated specific transmitter is possible. Each scissor code is uniquely determined by a code sequence generator that pre-reads a value unique to each transmitter. The bits of the scissors code are measured at the symbol rate of the main 8-VSB signal. This identification bit sequence is sent to the equivalent of a 2-VSB modulator for transmission on the 8-VSB main signal. By way of example, this identification signal will be transmitted at a power level low enough to minimize interference associated with standard digital television reception of the 8-VSB main signal.

  The starting point of the transmitter identification signal scissors code sequence will be emitted simultaneously with the first symbol of the first data segment following the data synchronization segment of the main 8-VSB signal. The scissors code sequence occurs in the data field as a fraction of 3, where the fourth sequence is truncated as soon as data segment synchronization is reached at the start of the next data frame synchronization segment. This identification signal is not transmitted during the data field sync segment and restarts on the data segment immediately following the data field sync segment.

  This identification signal can be used to transmit a low data rate signal by phase reversal of the code sequence associated with the transmitter. This phase reversal occurs under the data field-by-data field reference. Since the data field repeats every 24.2 ms, this data rate is 41.3 bits per second. This low data rate channel can be used to provide GPS assistance information.

  The present invention can be implemented in digital electronic circuitry or in computer hardware, firmware, software, or combinations thereof. The apparatus of the present invention can be implemented in a computer program product specifically embodied in a machine readable storage device for execution by a programmable processor, and the method steps of the present invention are programmable to execute a program of instructions. The functions of the present invention can be performed by being executed by a processor and operating on input data to produce output. The present invention can be advantageously implemented in one or more computer programs, can be executed on a programmable system including at least one programmable processor coupled thereto, and comprises a data storage system and at least one input device. And receiving data and instructions from at least one output device and transmitting data and instructions to them. Each computer program can be implemented in a high level procedural or object oriented programming language if desired, or in assembly or machine language. In any case, the language can be a translated or interpreted language. Suitable processors include, by way of example, both general and special purpose microprocessors. Generally, a processor will receive instructions and data from a read-only memory and / or a random access memory. Generally, a computer includes one or more mass storage devices for data file storage, such devices including a magnetic disk, such as an internal hard disk or a removable disk, a magneto-optical disk, and an optical disk. Suitable storage devices for unambiguously embodying computer program instructions and data include all forms of non-volatile memory. By way of example, it includes semiconductor memory devices such as EPROMs, EEPROMs and flash memory devices, magnetic disks such as internal hard disks and removable disks, magneto-optical disks, and CD-ROM disks. Some predecessors can be supplemented by or incorporated into an ASIC (Application Specific Integrated Circuit).

  A number of embodiments of the invention have been described. However, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the claims.

1 is a block diagram of a system according to the present invention. The structure of an ATSC frame is shown. 6 is a flowchart illustrating a method for transmitting and receiving data at a low data rate using an ATSC DTV signal. Fig. 4 illustrates a data segment replaced by a cipher word using various approaches. Fig. 4 illustrates a data segment replaced by a cipher word using various approaches. Fig. 4 illustrates a data segment replaced by a cipher word using various approaches. Fig. 4 illustrates a data segment replaced by a cipher word using various approaches. Fig. 4 shows a frame in which various data segments are replaced by cipher words. Fig. 4 shows a frame in which various data segments are replaced by cipher words. It is a block diagram of a DTV transmitter. It is a block diagram of the front end used with a receiver. It is a block diagram of the back end based on the correlator of 1 bank. It is a block diagram of one correlator. It is a block diagram of another correlator. 6 is a flowchart illustrating a method of digital data playback based on framing construction. It is a block diagram of the back end for framing construction. 1 illustrates a system including a GPS receiver and a plurality of GPS satellites according to an embodiment. FIG. 14 illustrates a process performed by the system of FIG. 13 according to an embodiment. 1 illustrates a system including only a GPS receiver and a single GPS satellite according to an embodiment. Fig. 4 illustrates a process performed by a system according to an aspect.

Claims (56)

  The satellite positioning system support information is configured to determine the position of the satellite positioning system receiver using satellite positioning system support information and a propagation time of a signal transmitted by a satellite of the satellite positioning system. A second satellite positioning system receiver for receiving the satellite positioning system support information, and a channel coder for providing a digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments; An encoder that encodes the satellite positioning system support information as a cipher word, a packet multiplexer that replaces a data segment in the digital television signal with the cipher word, and a transmitter that transmits the digital television signal, The satellite positioning system receiver receives the digital TV signal. And Shin, and wherein the reproducing the satellite positioning system assistance information.   The apparatus of claim 1, wherein the satellite positioning system is a global positioning system (GPS).   The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information. Equipment.   The satellite positioning system support information includes a position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system. 3. The system of claim 2, comprising at least one group consisting of information relating to atmospheric effects on the signal transmitted by a satellite and identification of the satellite positioning system satellite visible to the satellite positioning system receiver. apparatus.   The digital television signal includes the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB- 3. The apparatus of claim 2, comprising at least one group of T) signals.   An apparatus for reproducing satellite positioning system support information from a digital television signal, wherein the digital video signal includes a plurality of frames each consisting of a plurality of data segments, and at least one data segment is the satellite positioning system support information. A front end that receives the digital television signal replaced by at least one cipher word representing the data segment to be replaced by a cipher word and the satellite positioning system assistance information is selected from the data segment selected A device comprising a back end for playback.   The apparatus of claim 6, wherein the satellite positioning system is the global positioning system (GPS).   The satellite positioning system support information includes the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system satellite. 8. The apparatus of claim 7, comprising at least one group consisting of information relating to atmospheric effects on the transmitted signal and identification of satellite positioning system satellites visible to a satellite positioning system receiver.   The digital television signal includes the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB- 8. The apparatus of claim 7, comprising at least one group of T) signals.   An apparatus for determining a position of a satellite positioning system receiver using a satellite positioning system, wherein a signal transmitted by a satellite of the satellite positioning system is received, and a plurality of frames each consisting of a plurality of data segments are obtained. Receiving the digital television signal, wherein the at least one data segment is selected by selecting a front end to be replaced by at least one cipher word representing satellite positioning system assistance information, and the data segment being replaced by the cipher word A back end for reproducing the satellite positioning system support information from a data segment; and a processor for determining a position of the satellite positioning system receiver based on a signal received from the satellite positioning system satellite and the satellite positioning system support information; A device comprising:   The apparatus of claim 10, wherein the satellite positioning system is the global positioning system (GPS).   The satellite positioning system support information includes the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system satellite. 12. The apparatus of claim 11, comprising at least one group consisting of information relating to atmospheric effects on the transmitted signal and identification of the satellite positioning system satellites visible to the satellite positioning system receiver.   The digital television signal includes the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB- 12. The apparatus of claim 11 comprising at least one group of T) signals.   The processor determines a pseudorange between the satellite positioning system receiver and the transmitter of the digital television signal based on a known component of the digital television signal and receives the pseudorange and the satellite positioning system from the satellite 12. The apparatus of claim 11, wherein the position of the satellite positioning system receiver is determined based on the received signal and the satellite positioning system support information.   The satellite positioning system receiver is configured to determine the position of the satellite positioning system receiver using satellite positioning system support information and a propagation time of a signal transmitted by a satellite of the satellite positioning system. A device for providing support information, the second satellite positioning system receiver means for receiving the satellite positioning system support information, and a digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments. Channel coder means, encoder means for encoding the satellite positioning system support information as a cipher word, packet multiplexer means for replacing a data segment in the digital TV signal with the cipher word, and transmission for transmitting the digital TV signal Means for receiving the satellite positioning system. And wherein the reproducing the satellite positioning system assistance information by receiving the digital television signal.   16. The apparatus of claim 15, wherein the satellite positioning system is the global positioning system (GPS).   The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information. The device described.   The satellite positioning system support information includes the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system satellite. 17. The apparatus of claim 16, comprising at least one group consisting of information relating to atmospheric effects on the transmitted signal and identification of the satellite positioning system satellites visible to the satellite positioning system receiver.   The digital television signal includes the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB- 17. The apparatus of claim 16, comprising at least one group consisting of T).   An apparatus for reproducing satellite positioning system support information from a digital television signal, wherein each frame includes a plurality of frames each including a plurality of data segments, and at least one data segment represents the satellite positioning system support information. Front-end means for receiving the digital television signal replaced by a cipher word; and a back end for reproducing the satellite positioning system support information from the selected data segment by selecting the data segment replaced by the cipher word Means.   21. The apparatus of claim 20, wherein the satellite positioning system is the global positioning system (GPS).   The satellite positioning system support information includes the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system satellite. 22. The apparatus of claim 21, comprising at least one group consisting of information relating to atmospheric effects on the transmitted signal and identification of the satellite positioning system satellites visible to the satellite positioning system receiver.   Digital television signals include the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB-T). 23. The apparatus of claim 21, comprising at least one group of signals.   An apparatus for determining a part of a satellite positioning system receiver using a satellite positioning system, wherein a signal transmitted by a satellite in the satellite positioning system is received, and a plurality of frames each comprising a plurality of data segments Receiving a digital television signal comprising a frame, selecting a front end where at least one data segment is replaced by at least one cipher word representing satellite positioning system assistance information, and said data segment replaced by a cipher word; Backend means for reproducing the satellite positioning system support information from the selected data segment; and the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information. And a processor means for determining the position.   25. The apparatus of claim 24, wherein the satellite positioning system is the global positioning system (GPS).   The satellite positioning system support information includes the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system satellite. 26. The apparatus of claim 25, comprising at least a group consisting of information regarding atmospheric effects on the transmitted signal and identification of the satellite positioning system satellite visible to the satellite positioning system receiver.   The digital television signal includes the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB- 26. The apparatus of claim 25, comprising at least one group of T) signals.   The processor means determines a pseudo-range between the satellite positioning system receiver and the transmitter of the digital TV signal based on a known component of the digital TV signal, and from the pseudo-range and the satellite positioning system satellite 26. The apparatus of claim 25, wherein the position of the satellite positioning system receiver is determined based on the received signal and the satellite positioning system support information.   The satellite positioning system is configured to determine the position of a satellite positioning system receiver using satellite positioning system support information and the propagation time of a signal transmitted by a satellite of the satellite positioning system. A method for providing support information, comprising: providing the satellite positioning system support information, providing a digital television signal including a plurality of frames, each frame including a plurality of data segments; The satellite positioning system receiver receives the digital television signal, the satellite positioning system receives the digital television signal, and replaces the data segment in the digital television signal with the cipher word A method characterized by playing back support information.   30. The method of claim 29, wherein the satellite positioning system is the global positioning system (GPS).   31. The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information. the method of.   The satellite positioning system support information includes the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system satellite. 31. The method of claim 30, comprising at least one group consisting of information regarding atmospheric effects on the transmitted signal and identification of the satellite positioning system satellites visible to the satellite positioning system receiver.   The digital television signal includes the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB- 31. The method of claim 30, comprising at least one group of T) signals.   A method for reproducing satellite positioning system support information from a digital television signal, wherein the digital television signal comprises a plurality of frames, each frame comprising a plurality of data segments, wherein at least one data segment is supported by the satellite positioning system. Receiving the digital television signal replaced by at least one cipher word representing information, selecting the data segment replaced by the cipher word, and reproducing the satellite positioning system support information from the selected data segment; A method that consists of doing.   35. The method of claim 34, wherein the satellite positioning system is a global positioning system (GPS).   The satellite positioning system support information includes the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system satellite. 36. The method of claim 35, comprising at least one group consisting of information regarding atmospheric effects on the transmitted signal and identification of the satellite positioning system satellites visible to the satellite positioning system receiver.   The digital television signal includes the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB- 36. The method of claim 35, comprising at least one group of T) signals.   A method of determining a position of a satellite positioning system receiver using a satellite positioning system, wherein a signal transmitted by a satellite in the satellite positioning system is received by the satellite positioning system receiver, and each frame includes a plurality of frames. Receiving a digital television signal comprising a plurality of frames of data segments, wherein at least one data segment is replaced by at least one cipher word representing satellite positioning system assistance information, at the satellite positioning system receiver; Selecting the data segment replaced by, reproducing the satellite positioning system support information from the selected data segment, and based on the signal received from the satellite positioning system satellite and the satellite positioning system support information A method comprising determining the position of a satellite positioning system.   39. The method of claim 38, wherein the satellite positioning system is the global positioning system (GPS).   The satellite positioning system support information is transmitted by the satellite positioning system satellite, the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system, and the satellite positioning system satellite. 40. The method of claim 39, comprising at least one group consisting of information regarding atmospheric effects on the received signals and identification of the satellite positioning system satellites visible to the satellite positioning system receiver.   The digital television signal includes the American Television Standards Institute (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB-T). 40. The method of claim 39, comprising: at least one group of signals.   And determining a pseudo-range between the satellite positioning system receiver and the digital TV signal transmitter based on a known component of the digital TV signal, and receiving the pseudo-range and the satellite positioning system satellite received from the satellite positioning system satellite 40. The method of claim 39, comprising determining a position of the satellite positioning system receiver based on a signal and the satellite positioning system assistance information.   The satellite positioning system support to the satellite positioning system receiver configured to determine the position of the satellite positioning system receiver using satellite positioning system support information and a propagation time of a signal transmitted by a satellite of the satellite positioning system. A computer-readable medium embodying instructions executable by a computer for performing a method for providing information, the method providing the satellite positioning system support information, wherein each frame comprises a plurality of data segments. Providing a digital TV signal comprising a frame of the encoding, encoding the satellite positioning system support information as a cipher word, replacing a data segment in the digital TV signal with the cipher word, and transmitting the digital TV signal. The satellite positioning system receiver is connected to the digital television signal. Computer readable medium for reproducing the satellite positioning system assistance information by receiving a.   44. The medium of claim 43, wherein the satellite positioning system is a global positioning system (GPS).   45. The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system support information. Medium.   The satellite positioning system support information includes the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system satellite. 45. The medium of claim 44, comprising at least one group consisting of information relating to atmospheric effects on the transmitted signal and identification of the satellite positioning system satellites visible to the satellite positioning system receiver.   The digital television signal includes the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB- 45. The medium of claim 44, comprising at least one group of T) signals.   A computer-readable medium embodying instructions that can be executed by a computer executing a method for reproducing satellite positioning system assistance information from a digital television signal, wherein the digital video signal includes a plurality of data segments in each frame. Receiving the digital television signal comprising a plurality of frames of which at least one data segment is replaced by at least one cipher word representing the satellite positioning system assistance information, and the data replaced by the cipher word A computer readable medium comprising selecting a segment and reproducing the satellite positioning assistance information from the selected data segment.   49. The medium of claim 48, wherein the satellite positioning support system is the global positioning system (GPS).   The satellite positioning system support information includes the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system satellite. 50. The medium of claim 49, comprising at least one group of information relating to atmospheric effects on the transmitted signals and identification of the satellite positioning system satellites visible to the satellite positioning system receiver.   The digital television signal includes the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB- 50. The medium of claim 49, comprising at least one group of T) signals.   A computer-readable medium embodying computer-executable instructions for performing a method for determining a position of a satellite positioning system receiver using a satellite positioning system, the method being transmitted by a satellite of said satellite positioning system Received by the satellite positioning system receiver, each frame comprising a plurality of frames comprising a plurality of data segments, wherein at least one data segment is replaced by at least one cipher word representing satellite positioning system support information The digital positioning signal is received by the satellite positioning system receiver, the data segment replaced by a cipher word is selected, the satellite positioning system support information is reproduced from the selected data segment, and the satellite positioning is selected. The signal received from the system satellite and Serial satellite positioning system assistance information and computer-readable medium comprising determining the location of the satellite positioning system receiver based on.   53. The medium of claim 52, wherein the satellite positioning system is the global positioning system (GPS).   The satellite positioning system support information includes the position of the satellite positioning system satellite, clock correction information for the satellite positioning system satellite, Doppler information for the signal transmitted by the satellite positioning system satellite, and the satellite positioning system satellite. 54. The medium of claim 53, comprising at least one group consisting of information relating to atmospheric effects on the transmitted signal and identification of the satellite positioning system satellites visible to the satellite positioning system receiver.   The digital television signal includes the American Television Standards Committee (ATSC) digital television signal, the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (DVB-T) signal, and the Japan Terrestrial Digital Integrated Broadcasting Service (ISDB- 54. The medium of claim 53, comprising at least one group of T) signals.   Further, the method determines a pseudo-range between the satellite positioning system receiver and the transmitter of the digital TV signal based on a known component of the digital TV signal, from the pseudo-range and the satellite positioning system satellite. The medium of claim 53, wherein the position of the satellite positioning system receiver is determined based on the received signal and the satellite positioning system support information.

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