JP2010136434A - Receiver for receiving emergency prompt report in terrestrial digital television broadcast - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver for receiving transmission control signals for emergency prompt reports from terrestrial digital television broadcast waves. <P>SOLUTION: The receiver includes: a frame synchronization means for receiving broadcast waves including transmission control signals and performing frame synchronization based on synchronization signals included in the transmission control signals; a frame synchronization holding means 19 for holding the timing of the frame synchronization; a means 13 for demodulating flags disposed immediately after the synchronization signals; and a flag monitoring means for monitoring the value. Power is supplied to the frame synchronization means and the flag demodulation means 13 according to the reception timing of the flags when serving both as synchronization establishment and flag monitoring. When monitoring the flags after the synchronization establishment, power is supplied to the flag demodulation means according to the reception timing of the flags. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a technology for transmitting and receiving emergency bulletins in digital terrestrial television broadcasting, and in particular, a receiver that waits for a startup flag signal for emergency bulletins with low power consumption and promptly receives the bulletins when an emergency bulletin is issued. About.

  The Japan Meteorological Agency started providing emergency earthquake bulletins (see Non-Patent Document 1, for example) to the general public from October 1, 2007. Accordingly, television and radio broadcasting stations are also broadcasting such as displaying or sounding them on a television screen together with a chime sound when the breaking news is announced. In addition, a part of the earthquake early warning radio broadcast started on April 1, 2008.

  In the case of digital terrestrial television broadcasting, particularly in the case of a so-called one-segment service with partial reception (hereinafter simply referred to as one-segment), the delay required for signal processing such as radio frequency (RF) signal demodulation, error correction, and video codec etc. There will be a delay of several seconds before the earthquake early warning is displayed on the television screen. Moreover, if the receiver is not turned on, it will not be possible to receive emergency earthquake bulletins.

  In the case of emergency alert broadcasting, a mechanism is known that operates with reduced standby power consumption and activates a receiver whose power is not turned on to notify the receiver. For example, an ISDB-T (Integrated Services Digital Broadcasting-Terrestrial, ARIB standard STD-B31) terrestrial digital television receiver has TMCC (Transmission and Multiplexing Configuration Transmission Control) when the receiver is not powered on. ) By providing a transmission control signal receiving circuit for detecting an emergency warning broadcast activation flag stored in the carrier, when the emergency warning broadcast activation flag is 1 (there is an emergency warning broadcast), the receiver is turned on, The receiver can be prompted to watch the emergency alert broadcast (see, for example, Patent Document 1).

  At this time, the transmission control signal receiving circuit of the receiver includes a synchronization holding circuit based on the frame synchronization signal of the TMCC signal, and is intermittent in the frame and in the frame unit (outside frame) at the timing indicated by the count value by the synchronization holding circuit. Operates and saves power consumption. The power-on timing in the frame is, for example, about 30 msec from the synchronization signal to the emergency warning broadcast activation flag.

  There is also known a receiver that achieves lower power consumption by simplifying the circuit configuration of the transmission control signal receiving circuit (see, for example, Patent Document 2). In the receiver, diversity combining is further applied to all four TMCC signals in the partial reception segment.

  In addition to receiving an activation flag using a TMCC signal for transmission in terrestrial digital television broadcasting such as disaster and disaster prevention information including earthquake early warning, a technique using an AC (Auxiliary Channel) carrier is also known (for example, And Patent Document 3). In this technology, the emergency broadcast type and the start or end of the emergency broadcast are presented by a combination of an emergency warning broadcast activation flag of the TMCC carrier and a signal type bit placed on a specific AC carrier in the partial reception segment, for example. In addition, ARIB standard STD-B10 emergency information descriptor and emergency broadcast video / audio are transmitted using an AC carrier. This emergency information descriptor includes a signal type bit and is transmitted in an AC signal of a partially received segment, and the video / audio is stored in an AC signal of another segment.

  Further, it is disclosed that the power is turned on or the channel is switched in preparation for the case where the receiver is not turned on or another channel is received. For this control, the TMCC signal in the partial reception segment is disclosed. And a technique for reproducing other disaster / disaster prevention information and video / audio after receiving an AC signal and after power-on or channel switching (see, for example, Patent Document 3).

JP 2006-319771 A JP 2007-104221 A JP 2007-243936 A

“Technical reference materials on overview and processing methods of earthquake early warnings,” Japan Meteorological Agency Earthquake Volcano, [Search on January 31, 2008], Internet <URL: http://www.seisvol.kishou.go.jp/ eq / EEW / kaisetsu / Whats_EEW / reference.pdf>

  All of the above-described techniques are related to a terrestrial digital television broadcast receiver in that the purpose is to quickly start up a receiver of a receiver who is not viewing. However, it is necessary to wait for the emergency early warning activation flag signal with low power consumption, and when the emergency early warning is issued, the receiver is activated from the viewpoint of receiver technology when the purpose is to transmit the emergency early warning promptly. There is room for improvement in the signal transmission method.

  For example, in the current standard (ARIB standard STD-B31), an emergency warning broadcast activation flag is provided in the TMCC signal, but this flag is the 26th bit (Note: the first bit of the frame is the 0th bit) 27) including 27 periods including the period of 9 symbols from the 17th bit to the 25th bit when the power consumption is saved by the intermittent operation within the frame in which the start flag is monitored while observing the synchronization signal. There is a need to.

  Further, since the technique described in Patent Document 3 receives both the TMCC signal and the AC signal, the circuit configuration is further complicated as compared with the techniques described in Patent Documents 1 and 2.

  Furthermore, Patent Document 3 does not describe a specific message information format of an AC signal such as an activation flag.

  The present invention allows a receiver of a digital terrestrial television broadcast to wait for an emergency early warning activation flag signal with low power consumption even when the receiver has not received the broadcast, and promptly issue an emergency early warning. In addition, another object of the present invention is to provide a receiver that can transmit the breaking news.

  The receiver of the present invention is a receiver that receives a transmission control signal from a terrestrial digital television broadcast wave, and recognizes a frame length of the transmission control signal to perform frame synchronization, and the synchronization signal Message information including a flag identifying whether or not there is an emergency early warning is specified in advance so that the transmission control signal is transmitted from the transmission side by the transmission control signal, and the carrier of the transmission control signal is received. Frame synchronization means for performing frame synchronization based on a synchronization signal included in the transmission control signal, frame synchronization holding means for holding frame synchronization timing for a certain period after frame synchronization, and a carrier of the received transmission control signal. A flag demodulating means for demodulating the flag; a flag monitoring means for monitoring the value of the flag arranged immediately after the synchronization signal; And the flag reception timing when the synchronization is established and the flag demodulation means is supplied with power to the frame synchronization means and the flag demodulation means according to the reception timing of the synchronization signal and the flag. And a power control means for supplying power to the flag demodulating means, wherein the power control means matches the last bit of the synchronization signal and the reception timing of the flag when flag monitoring is performed after synchronization is established. Power is supplied to the demodulating means.

  In the receiver of the present invention, the power control means supplies power intermittently between a plurality of frames with respect to the reception timing of the synchronization signal and the flag when both synchronization establishment and flag monitoring are performed. .

  In the receiver according to the present invention, the flag monitoring means makes a majority decision using the plurality of flags received between the plurality of frames.

  In the receiver according to the present invention, the flag demodulating means delay-detects the flag with reference to the last bit of the synchronization signal.

  In the receiver of the present invention, the carriers are eight AC carriers in the ISDB-T system of terrestrial digital television, and the flag monitoring means receives from the eight AC carriers in order to obtain diversity gain. The flag is synthesized and monitored.

  According to the present invention, an emergency early warning is issued to a receiver of a terrestrial digital television broadcast while waiting for an emergency early warning activation flag signal with low power consumption even when the receiver does not receive the broadcast. It is possible to quickly transmit the breaking news.

It is a figure explaining the transmission method of the starting flag which concerns on this invention. It is a figure which shows the format of the message | telegram information which concerns on this invention, and the operation example of the power supply control of the receiver in the intermittent reception mode in a flame | frame. It is a block diagram of the receiver of Example 1 which concerns on this invention. It is a flowchart showing the power-saving algorithm example of the intermittent reception mode in the frame of the starting flag signal monitoring in the receiver of Example 1 of this invention. It is a block diagram of the receiver of Example 2 by this invention.

  First, a method for transmitting a start flag signal according to the present invention will be described.

  FIG. 1 is a diagram for explaining a method of transmitting an activation flag signal for emergency bulletins such as emergency earthquake bulletins and emergency warning broadcasts (hereinafter, the term “emergency bulletin” will be used when describing both together). .

  In FIG. 1, as an example, an OFDM transmission signal and an AC signal in the terrestrial digital television broadcast of mode 3 ISDB-T will be described. As shown in FIG. 1A, the transmission signal of the mode 3 ISDB-T system includes 432 carriers of 204 symbols, and includes 8 AC signals. FIG. 1 (b) schematically illustrates an AC signal according to the present invention.

  In the present invention, in the message information format, when the activation flag signal is represented by 1 bit of “1” or “0” (assuming that there is an emergency early warning when “0”), the activation flag signal is used for frame synchronization. It is arranged and transmitted immediately after the synchronization signal to be added. However, the “activation flag signal” can be composed of 2 bits. In this case, “00” indicates “there is an emergency warning” and “11” indicates “there is no emergency warning”. Therefore, the activation flag signal functions as a flag (start / end flag) indicating the start / end of transmission of emergency early warning (for example, earthquake motion warning information).

  As shown in FIG. 1B, when the synchronization signal and the start flag signal are continuously arranged, the on-time of the intermittent operation used when monitoring the start flag signal targeted by the present invention with low power consumption is minimized. There is a feature that can be the number of symbols.

  In addition, there is an advantage that several parameters are defined and described below.

In transmission of terrestrial digital television broadcasting of the ISDB-T system, an OFDM (Orthogonal Frequency Division Multiplexing) system is used. Therefore, the transmission signal, propagation path characteristic, reception signal and noise of symbol l and carrier k (l and k are integers) are expressed as s (l, k), h (l, k), r (l, k), n. If (l, k) is set, these have the following relationship.
r (l, k) = h (l, k) × s (l, k) + n (l, k) (1)
Usually, only the received signal r (l, k) has a known value.

  In the ARIB standard STD-B31, a TMCC signal and an AC signal are mapped to a DBPSK modulated wave and transmitted.

When this modulated wave is transmitted by replacing the information with a phase change between two symbols before and after, information d (d is assumed to be “−1” or “1”) is transmitted by two consecutive symbols l ₁ and l _2. Therefore, there is a relationship of the following equation between the information d and the transmission signals s (l ₁ , k) and s (l ₂ , k).
s (l ₂ , k) = d × s (l ₁ , k) (2)
In the equation (1), substituting the symbols l ₁ and l ₂ yields the following equation:
r (l ₁ , k) = h (l ₁ , k) × s (l ₁ , k) + n (l ₁ , k) (3)
r (l ₂ , k) = h (l ₂ , k) × s (l ₂ , k) + n (l ₂ , k) (4)
Here, if h (l, k) does not change between the symbols l ₁ and l ₂ and the noise n (l, k) is small enough to be ignored as compared with the other, the equation (4) is changed to (3) By dividing by the expression, the information d can be demodulated as shown in the following expression.
r (l ₂ , k) / r (l ₁ , k) ≈s (l ₂ , k) / s (l ₁ , k) = d
... (5)

  For this reason, when receiving a signal, a DBPSK modulated wave is used in a TMCC signal or an AC signal that transmits information related to transmission control that is demodulated before anything.

  Multiplication by phase conjugation between two symbols, which is a modification of equation (5) or equation (5), is a typical technique of asynchronous detection or delay detection.

  However, in the delay detection, the C / N necessary to obtain the same bit error rate (BER) is increased by about 1 dB as compared with the synchronous detection, so even if the receiver is in a pocket or a bag, it is an emergency. This is a problem when trying to receive a prompt flag signal for breaking news with high sensitivity.

  Also for diversity reception (in the case of one segment), four TMCC signals and eight AC signals cannot be used effectively. Theoretically, improvements of 6 dB and 9 dB are expected, respectively. However, the noise n (l, k) cannot be ignored, and the change in the propagation path characteristic h (l, k) cannot be ignored.

  Therefore, it can be considered to be understood as a BPSK modulated wave and received by synchronous detection.

  In the bit immediately after the synchronization signal, the state of each frame phase has a known value.

  For this reason, even a DBPSK modulated wave can be handled as if it were a BPSK modulated wave for a signal arranged immediately after the synchronization signal.

In a conventional ISDB-T terrestrial digital television broadcast, an SP signal p (l, k) having a known amplitude and phase value together with data is acquired so that the propagation path characteristic h (l, k) can be acquired. Is transmitting. Again, assuming that the noise n (l, k) can be ignored, the propagation path characteristic h (l, k) can be calculated from the equation (1) for the symbol l and the carrier k where the SP signal is transmitted. Is the estimated value of h (l, k), and the propagation path characteristics h (l _t , k), h at the carrier position of the TMCC signal or AC signal using the DBPSK modulated wave defined in the ISDB-T standard (L _a , k) is obtained by interpolation and the estimated values of the transmission signals s (l _t , k) and s (l _a , k) are calculated. As a result, in the equation (1), the propagation path characteristic h (l, k) can be made approximately known.

  Therefore, in the transmission system of each embodiment according to the present invention, the DBPSK modulated wave is handled in the same manner as the BPSK modulated wave by adopting a telegram information format in which the activation flag signal is arranged immediately after the synchronization signal as shown in FIG. In addition to the delay detection, a demodulation method by synchronous detection can be selected.

  Next, a receiver according to an embodiment of the present invention will be described.

  FIG. 2A shows a message information format according to the first embodiment of the present invention.

  The transmitting apparatus according to the present invention transmits emergency early warning based on the telegram information format of the first embodiment shown in FIG. 2A to each subcarrier multiplexed in the OFDM system of ISDB-T terrestrial digital television broadcasting. Of these, transmission is performed using an AC carrier. The hardware configuration of the transmission apparatus related to ISDB-T digital terrestrial television broadcasting is known and not shown. However, a transmission apparatus that transmits message information using transmission control information (TMCC or AC), a receiver that receives the message information and performs a specific operation, and a transmission that includes these transmission apparatuses and receivers The system performs unique functions as described below.

  The frame length is the same as that of the TMCC signal, is composed of 204 symbols of the OFDM signal, and 1 bit is transmitted for each symbol.

The “differential demodulation reference” is a value based on the same generator polynomial (x ¹¹ + x ⁹ +1) as the value W _{k of the} BPSK signal assigned to the SP signal of the carrier number k, similarly to the TMCC signal. In the case of an AC carrier (synchronous modulation unit in mode 3) in a partial reception segment (segment number # 0) of a T digital terrestrial television broadcast wave, carrier numbers # 7, # 89, # 206, # 209, # 226 , # 244, # 377 and # 407. The W _k stored as the differential demodulation reference described in the AC information carried by the eight AC carriers are 0, 0, 0, 0, 0, 1, 1 and 0, respectively.

The “synchronization signal” is a 16-bit synchronization signal, and the value thereof is “0011010111101110” (odd frame) and its inverse (even frame), which are different values in the odd and even frames. In the DBPSK modulated wave, when W _k is 0, the odd frame is “1,1, -1,1,1, −1, −1,1, −1,1, −1, −1,1, − 1,1,1 ", and even frames are" -1,1,1,1, -1, -1, -1,1,1,1,1, -1, -1, -1, -1, -1, " 1 ”. When W _k is 1, these are inverted.

  Thus, the “synchronization signal” is a signal having a known amplitude and phase.

  In the present embodiment, the 1-bit “start flag signal” for identifying the presence or absence of the emergency early warning follows the “synchronization signal”. The value of the “activation flag signal” is the value representing the bit of “0” when there is an emergency warning, and the phase of the last symbol of the “synchronization signal” is continued. Inverts the phase as a value representing the 'bits. In addition, when transmitting the same information on each carrier when transmitting with 8 AC carriers, dividing the value of the activation flag in each carrier by the value of “reference of differential demodulation” is the same for all carriers. Therefore, diversity combining is possible.

  It should be noted that in this description, in order to facilitate understanding of the present invention, AC information carried by an AC carrier in a mode 3 partial reception segment (segment number # 0) in ISDB-T terrestrial digital television broadcasting However, it should be noted that the present invention can be applied to other modes.

  The “emergency bulletin identification signal” is a signal indicating the type of emergency bulletin. It provides information on whether the emergency bulletin represents an emergency earthquake bulletin (earthquake motion warning) or an emergency warning broadcast. For example, 3 bits are used, “000” is an emergency earthquake warning, “001” is an emergency warning broadcast, “010” is an emergency earthquake warning test signal, and “011” is an emergency warning broadcast test signal. As with the “activation flag signal”, each 3-bit value is transmitted as a DBPSK-modulated value.

  When the “activation flag signal” indicates a value of “0” (there is an emergency bulletin), the value of the “emergency bulletin identification signal” is read to identify the type of emergency bulletin, that is, what the emergency bulletin is.

  “Various identification signals” include information signals accompanying emergency bulletins such as “breaking news ID” (12 bits), “information number” (4 bits), “message type” (2 bits), and signals such as broadcaster identification. Is applicable.

  “Breaking news ID” is inserted as an identification number (ID number) of emergency breaking news. For example, an earthquake early warning published by the Japan Meteorological Agency has an earthquake identification number that starts with “ND” and is created by arranging (year), month, day, hour, minute, and second. The lower 12 bits of this number are allocated and used. In other cases such as emergency alert broadcasting, an identification number is assigned in the same way.

  This “breaking news ID” makes it possible to discriminate between the breaking news and other breaking news even if a follow-up or cancellation information is generated in the same emergency bulletin.

  The “information number” is a number that is incremented by one each time a bulletin is announced when a subsequent report is issued. It is given so that the receiver can recognize that it is a series of information and an emergency bulletin issued earlier. It is used repeatedly in the range of 0-15.

  The “message type” is used to indicate whether normal transmission in which an emergency bulletin is issued or whether the previously issued emergency bulletin is canceled (cancellation). Store it so that it can be canceled if a false early warning is generated. Using two bits, for example, “00” indicates emergency warning broadcast or emergency earthquake early warning for general public, and “01” indicates cancel information. If there is no emergency bulletin, “11” can be transmitted to provide insurance against the determination of the “activation flag signal”.

  For broadcaster identification, an identification signal based on the ARIB standard STD-B14 can be used. In this case, “broadcast area identification” (6 bits), “prefectural compound flag” (1 bit), and “area operator identification” (4 bits) are stored.

  Similarly, “each identification signal” is also subjected to DBPSK modulation.

  “Emergency early warning information” is a part in which necessary information is stored for information that needs to be transmitted separately from broadcast, such as emergency earthquake early warning.

  A specific example is given in the case where the target of emergency warning is emergency earthquake warning and emergency warning broadcast. Information is stored only for emergency earthquake warning, and fixed bit (for example, all '1') for emergency warning broadcast. Is placed.

  Of the earthquake early warning information, the information that should be transmitted separately from the broadcast is the minimum necessary information for the receiver when the earthquake early warning is issued, and it is transmitted accurately, quickly and reliably. Information to be done. That is, it is information that allows the receiver to recognize how much magnitude / seismic magnitude of the earthquake will occur in the area where the receiver is located.

  Specifically, two method examples are shown.

  In the case of a strong earthquake (seismic intensity of 5 or less), it is desirable that the general emergency earthquake information be transmitted with information on the scale and the area where the seismic intensity of 4 or more is estimated.

  The first method case directly conveys an area where strong shaking is expected.

  In other words, it is a “strong earthquake area with seismic intensity 4 (prefecture unit)” (56 bits) for national broadcasting, and a “strong earthquake area (regional unit) with seismic intensity 4 or more” (38 bits) for prefectural or wide area broadcasting. ). It is a “region where strong shaking is estimated” used in emergency earthquake warnings for general public. One bit is assigned to each region, and 0 or 1 indicates whether or not it is a target. The region of “strong earthquake areas with seismic intensity of 4 or more (prefectural units)” is currently 56 areas nationwide, with prefectures as units and Hokkaido divided into four. The “strong earthquake region (regional unit) with seismic intensity 4 or higher” is the smallest regional unit to which the Japan Meteorological Agency assigns a region code. When divided into wide-area broadcasting areas, the maximum is 38 regions in Hokkaido.

  For example, when Tokyo, Kanagawa, and Izu Islands are predicted to have a seismic intensity of 4 or more, the bits assigned to these three regions are set to 0, and the others are set to 1. Therefore, on the transmitting side, data based on this value is transmitted, and on the receiving side based on this value, “Earthquake Early Warning (Meteorological Agency): Earthquake occurred. Be wary of strong shaking in the following areas: Tokyo, Kanagawa Prefecture, A message such as “Izu Islands” is displayed.

  In order to distinguish national broadcasting from prefectural or wide-area broadcasting, a 2-bit national prefectural identification flag signal is transmitted, “01” for national broadcasting, “00” for prefectural broadcasting or wide-area broadcasting, and “11” when not in use. Shall be transmitted.

  In addition, “maximum predicted seismic intensity” (4 bits) is stored as necessary.

  The “maximum predicted seismic intensity” corresponds to seismic intensity 4 or higher of 4, 5 weak, 5 strong, 6 weak, 6 strong, or 7. “Strong” and “weak” are distinguished by 1 and 0 respectively. Therefore, “0100”, “0101”, “1101”, “0110”, “1110”, and “0111” can be distinguished. However, this maximum predicted seismic intensity is the maximum predicted seismic intensity that is expected to be observed in any region of Japan due to the earthquake if it is nationwide broadcast, not for each specific region, and if it is a wide area or prefectural area broadcast, It is the maximum predicted seismic intensity that is expected to be observed in the area. An emergency earthquake bulletin is issued when the maximum predicted seismic intensity predicted to be observed in any part of Japan is greater than 5 seismic intensity.

  The second method example is an indirect method that transmits detailed earthquake information such as time of occurrence, epicenter latitude, longitude, depth, and magnitude, and calculates the predicted seismic intensity and predicted arrival time at the receiver that received the information. It is. More detailed alerts can be made for each region based on the recipient's wishes.

  According to Non-Patent Document 1, the predicted arrival time of predicted seismic intensity and strong ground motion (main motion) can be calculated from the acquired location information (latitude and longitude, depth) of the earthquake source, the magnitude of the earthquake (magnitude), and the degree of ground amplification. .

First, the predicted seismic intensity is calculated as the measured seismic intensity I _{INSTR by the} following formula.
I _INSTR = 2.68 + 1.72 log (PGV) ± 0.21 (6)
Here, PGV is the maximum speed [cm / s] of each point on the ground surface, and the maximum speed PGV ₆₀₀ on the reference base (hard base, S wave speed 600 m / s) calculated by the maximum speed attenuation formula is a value obtained by multiplying the site amplification degree ARV _i at the point to be the target in the national land information.
PGV = 1.31 PGV ₆₀₀ × ARV _i (7)
The maximum velocity decay equation is expressed by equation (8), and information necessary for calculating PGV ₆₀₀ [cm / s] is magnitude M, epicenter depth D [km] and fault shortest distance x [km. ] Only.
log (PGV ₆₀₀ ) = 0.58 (M−0.171) +0.0038 D−1.29
-Log (x + 0.028 × 10 ^{0.50 (M−0.171)} ) −0.002x (8)

  Assuming that the receiver has means for acquiring the position information and the point where the receiver is present is known, x can be easily calculated from the position information of the epicenter and the position information of the receiver.

Moreover, since ARV _i is a value depending on the location, it can be selectively used based on the position information by being stored in advance in the receiver.

Therefore, the measured seismic intensity I _INSTR can be easily calculated in the receiver by acquiring the location information and magnitude of the epicenter which is unknown in the receiver from the transmission side.

In addition, since the measured seismic intensity I _INSTR is calculated as a numerical value including a decimal point, the maximum predicted seismic intensity in the seismic intensity class is determined based on the relationship between the two shown in the following table.

  On the other hand, the estimated arrival time (required arrival time) from the time of the occurrence of the earthquake at the location where the receiver is located is the travel time table shown by the Japan Meteorological Agency based on the epicenter distance Δ [km] and the focal depth D [km] (For example, JMA2001) can be used for calculation. The epicenter distance Δ is a value that can be calculated from the location information (latitude and longitude) of the epicenter and the location information of the receiver.

  Therefore, in this case, the “emergency breaking information” includes the “earthquake occurrence time” (17 bits), “seismic latitude” (11 bits), “seismic longitude” (12 bits), “ The “depth of the epicenter” (10 bits) and the “magnitude” (7 bits) are stored.

  “Earthquake occurrence time” is the time when the earthquake occurred, estimated after observation of the P wave and transmitted to the broadcasting station by the emergency earthquake warning for the general public.

  The time of “earthquake occurrence time” is displayed in a range of 24 hours, the hour display is 5 bits, the minutes and seconds are 6 bits, for example, 13:25:37 is “01101 | 011001 | "100101" (17 bits in total), and binary numbers are displayed in units of hours, minutes, and seconds. In order to make it easy to see the distinction between hour, minute, and second, “|” is inserted only as a notation here, and is not inserted in actual transmission.

  “Latitude of the epicenter” and “longitude of the epicenter” represent the position of the epicenter on the ground surface. For example, latitude and longitude expressed with 1/10 degree accuracy such as 36.3 degrees north latitude and 136.5 degrees east longitude. Longitude. These are expressed as a numerical value of 10 times excluding the decimal point, with north latitude and east longitude being positive values, south latitude and west longitude being negative values.

  That is, “the epicenter latitude” and “the epicenter longitude” are “363” and “1365”, respectively, and 11 bits and 12 bits are assigned and expressed in binary numbers such as “00101101011” and “010101010101”. Note that the negative value of south latitude or west longitude is a one's complement. For example, 36.3 degrees south latitude is expressed as “11010010100”.

  The “depth of the epicenter” is the depth of the epicenter from the ground surface, and is expressed as a numerical value with the unit [km]. For example, in the case of 30 km, it is “30” and is expressed by a 10-bit binary number “0000011110”.

  “Magnitude” is a magnitude value indicating the magnitude of the earthquake, and is a numerical value with one decimal place, for example, “3.5”. This is expressed as a 10-fold numerical value. That is, it is “35” and is a 7-bit binary number “0010011”.

  In addition to the information based on the above two methods, information such as “page number” (2 bits) is added to “emergency breaking information” and transmitted. The “page number” is used for transmitting “emergency breaking information” by the above two methods over two frames and distinguishing information based on both methods when improving the convenience of the receiver.

  In the case of an AC carrier in a partial reception segment (segment number # 0) of an ISDB-T terrestrial digital television broadcast wave, for example, in the case of a mode 3 synchronous modulation unit, it is necessary to transmit 204 symbols, that is, one frame. A short time is 0.231 seconds. When the “emergency breaking information” by the above two methods is transmitted over two frames, the time required to view one frame information increases, but the alarm itself can be issued when any frame is detected.

  Similarly, “emergency breaking information” is DBPSK modulated.

  The “parity bit” is a parity bit used for error correction. Parity bits that enable error correction are targeted for 105 bits from the 18th bit excluding 17 bits to the 122nd bit immediately before the “parity bit” in addition to the “differential demodulation standard” and “synchronization signal”. 82 bits are stored. For example, similarly to the ISCC-T TMCC signal, error correction coding is performed using the shortened code (187, 105) of the difference set cyclic code (273, 191). Since error correction of about 8 bits is possible, the reliability of information can be increased and more reliable transmission can be achieved.

  The “parity bit” is also DBPSK modulated.

  The “reserved bit” is a reserved bit for future expansion. Normally, “1” is stored. When “Emergency Early Warning Information” transmits the information of Method 1 to prefectures nationwide and transmits “maximum predicted seismic intensity” and “page number”, 10 bits remain in the “reserved bit”. In the method 2, it is 13 bits similarly.

  Here, the reserve bits are put together, but there are cases where it is easier to cope with changes during the operation if the configuration is made by adding necessary information units.

  The “reserved bit” is also DBPSK modulated.

  In the present embodiment, for example, when receiving an earthquake early warning from the Japan Meteorological Agency, the broadcaster uses, for example, the ISDB-T system ground based on the format example of the telegram information shown in FIG. Considering the case of an AC carrier (synchronous modulation unit in mode 3) in a partial reception segment (segment number # 0) of a digital television broadcast wave, there are eight AC carriers, all of which have the same information for each carrier. It is stored and transmitted as a DBPSK modulated wave based on “differential demodulation criteria”.

  In addition, although the example of transmitting a DBPSK modulated wave in accordance with the description of the ARIB standard STD-B31 has been described, '1' is set based on 'differential demodulation reference' so that diversity gain can be improved at the receiving stage. It is also conceivable to transmit as a BPSK modulated wave to be set.

  Next, the receiver of Example 1 by this invention is demonstrated.

  As described above, the transmission side synchronizes with the eight AC carriers in the partial reception segment of the digital terrestrial television broadcast, for example, as the telegram information including the emergency early warning (the telegram information format shown in FIG. 2A). The activation flag signal for identifying the signal and the emergency bulletin is continuously transmitted, and the emergency bulletin identification signal, various identification signals, emergency bulletin information, the reserve bit, and the parity bit of the error correction code are transmitted.

The receiver of Example 1 by this invention receives the format of the message | telegram information shown to FIG. 2 (A). Here, the receiver can be included in any device such as a mobile phone, a personal digital assistant (PDA), a wristwatch, a table clock, a personal computer, or a home appliance.
In the description of each embodiment of the present invention, including the first embodiment, the information on the emergency bulletin is transmitted by the AC signal in the partial reception segment (segment number # 0) of the ISDB-T terrestrial digital television broadcast wave. It is supposed to be done. Many mobile / mobile terminals such as mobile phones receive this partial reception segment (segment number # 0) and watch programs (one-segment service). Therefore, the receiver of each embodiment of the present invention provided in a mobile phone or the like can receive an AC signal that transmits information on emergency breaking news. On the other hand, the receiver of each embodiment of the present invention provided in a digital TV for fixed reception that receives other segments also receives an emergency signal by receiving the AC signal in the partial reception segment. Can receive information.

  FIG. 3 is a block diagram of the receiver according to the first embodiment. The receiver according to the first embodiment includes an antenna 1, an AC reception / synchronization establishment unit 2, an AC information analysis unit 3, a synchronization hold / power control unit 4, a warning generation unit 5, a power source 6, an AC reception / A first power switch 7 for switching power supply to the synchronization establishing unit 2 and a second power switch 8 for switching power supply to the AC information analyzing unit 3 are provided.

  The AC reception / synchronization establishment unit 2 includes an AC reception unit and a synchronization establishment unit, and the AC reception unit includes a frequency conversion unit 9, an AD conversion unit 10, an FFT 11, an AC extraction unit 12, and an activation flag demodulation unit 13. The synchronization establishment unit includes a frame synchronization detection unit 14 and a symbol synchronization unit (not shown).

  Further, the AC information analysis unit 3 includes an AC demodulation unit 15, an error correction unit 16, an AC decoding unit 17, and an information processing unit 18. The information processing unit 18 includes a position detection unit and a current time detection unit (not shown).

  The synchronization holding / power control unit 4 includes a frame synchronization holding unit 19, a timing control unit 20, an activation flag monitoring unit 21, and a power supply control unit 22.

  Hereinafter, the function of each component of the receiver shown in FIG. 3 will be described.

  The frequency converter 9 removes unnecessary frequency components from a received signal of digital terrestrial broadcast waves input from the antenna 1 using a predetermined filter, selects a designated channel, and converts the frequency into an intermediate frequency signal. Amplify as appropriate and output. This channel selection can also be predetermined by the receiver.

  The AD conversion unit 10 converts the intermediate frequency signal of the reception signal output from the frequency conversion unit 9 into digital, and sends out a digital baseband signal.

  The FFT 11 performs an FFT (Fast Fourier Transform) operation on the effective symbol period of the OFDM symbol, and demodulates the digital baseband signal of the received signal into an OFDM format stream. The effective symbol period can be defined by performing symbol synchronization by a guard interval correlation or the like in a symbol synchronization unit (not shown), and performs an FFT operation at an FFT sample frequency according to a predetermined transmission mode.

  The AC extraction unit 12 extracts only eight AC carriers in the partial reception segment (segment number # 0) from the OFDM stream of the received signal. The AC carrier extracted here is first supplied to the frame synchronization detection unit 14 and the activation flag demodulation unit 13.

  The frame synchronization detection unit 14 is a predetermined, for example, mode of the AC carrier of the received signal extracted by the AC extraction unit 12 and the same DBPSK modulated wave that is stored and transmitted as a “synchronization signal” in the AC signal. 3, detection of coincidence with the pattern is performed, and when both coincide, a frame synchronization signal (reset pulse) is generated at the head timing of the AC signal. Further, emergency breaking synchronization establishment information indicating whether or not emergency breaking frame synchronization is established is generated based on the frame synchronization signal.

  The activation flag demodulator 13 is the last symbol (the 16th symbol, the 17th symbol of the frame, the 1st symbol) of the synchronization signal of each frame from the stream of the eight AC carriers in the received signal extracted by the AC extractor 12. The start flag signal (17th symbol) is extracted, delay detection is performed based on equation (5), the start flag signal is demodulated, and the value of the transmitted start flag signal is estimated.

  Note that the calculation of equation (5) is a division between two symbols of received signals for the calculation of a binary signal, for example, the phase conjugate of the received signal of the 16th symbol and the received signal of the 17th symbol. The amount of calculation can be reduced by substituting with multiplication by.

  In diversity combining based on eight (eight) AC carriers, the phase conjugate product between the received signals for the two symbols is performed for eight carriers and integrated.

  The frame synchronization holding unit 19, the timing control unit 20, the activation flag monitoring unit 21, and the power supply control unit 22 in the synchronization holding / power supply control unit 4 are always supplied with power from the power supply 6.

  The frame synchronization holding unit 19 includes, for example, a clock generator and a counter, and is controlled based on the frame synchronization signal output from the frame synchronization detection unit 14. The clock generated by the clock generator is counted by the counter, and the count value is A frame pulse is generated every time the predetermined value is reached, and the count value is reset according to a frame synchronization signal (reset pulse), and this frame pulse is supplied to the timing control unit 20. As a result, the frame synchronization holding unit 19 can generate a self-held frame pulse.

  From the frame pulse from the frame synchronization holding unit 19 and the emergency early warning synchronization establishment information from the frame synchronization detection unit 19, the timing control unit 20 determines whether to perform an inter-frame intermittent reception mode, an intra-frame intermittent reception mode, or these A combination intermittent reception mode is determined, and an on / off (0 or 1 value) control signal is transmitted at the timing of each intermittent reception mode.

  The activation flag monitoring unit 21 acquires the value of the activation flag signal output by the activation flag demodulation unit 13, samples and holds the value, and outputs the value to the power supply control unit 22.

  Although not shown, the timing at which the activation flag monitoring unit 21 detects the activation flag signal is also controlled based on the frame pulse output from the frame synchronization holding unit 19.

  When the output value of the activation flag monitoring unit 21 detects “1” of the activation flag signal (that is, a normal state with no emergency warning), the power supply control unit 22 detects the AC reception / synchronization establishment unit 2. The first power switch 7 is controlled so as to control the power supply. On the other hand, when the activation flag monitoring unit 21 outputs the activation flag signal “0” (that is, the state where the emergency early warning has been issued), the power supply to the AC reception / synchronization establishment unit 2 is continued. The first power switch 7 is switched as described above, and the second power switch 8 is switched so as to start power supply to the AC information analysis unit 3.

  On the contrary, if the power supply control unit 22 determines that the activation flag signal value “0” indicating that there is an emergency warning is changed to the normal state “1”, the timing control unit 22 The power supply to the AC reception / synchronization establishment unit 2 is controlled by the first power switch 7 so that only the value of the activation flag signal is constantly monitored at the timing of the control signal from the AC information analysis unit 3 The second power switch 8 is switched so that the power supply to is interrupted.

  As a result, it is possible to reliably and immediately obtain information on the emergency bulletin while saving power consumption extremely.

  When power is supplied to the AC information analysis unit 3, the AC demodulation unit 15, the error correction unit 16, and the AC decoding unit 17 are sequentially activated. In synchronism with the frame synchronization signal generated by the frame synchronization detection unit 19, the AC demodulation unit 15 first selects all eight locations in the partial reception segment (segment number # 0) extracted from the OFDM format stream of the reception signal. After the DBPSK modulated wave on the AC carrier is detected and diversity combined by the same operation as that of the activation flag demodulating unit 13, a level determination of 0 or 1 is performed to obtain an AC signal bit stream.

  Subsequently, the error correction unit 16 corrects the error of the received bit stream of the AC signal based on the value of the parity bit using, for example, a difference set cyclic code method.

  Then, the AC decoding unit 17 decodes the content of each signal in a decoding format corresponding to the encoding method on the transmission side, that is, “activation flag signal”, “emergency early warning identification signal”, “various identification signals”, and “emergency early warning information”. Decrypt the contents of.

  At this time, the error correction unit 16 confirms whether or not the error correction of the bit stream of the AC signal is possible, and if there is an error that cannot be corrected, the error correction unit 16 does not output the signal and there is a reception error toward the AC decoding unit 17. A control signal to the effect is output and monitoring of the start flag signal is continued.

  The power supply control unit 22 can also be controlled to supply power to the AC information analysis unit 3 in the intra-frame intermittent reception operation or the inter-frame intermittent reception operation so as to acquire only all the information of the emergency bulletin. . In particular, when operating in the inter-frame intermittent reception operation, the activation flag demodulator 13 and the AC demodulator 15 can be operated so as to send the result of majority decision between a plurality of frames.

  In the receiver according to the present invention, various modes of detecting or correcting AC information errors and decoding can be considered, and will be collectively described as a “decoding unit”.

  The information processing unit 18 receives the contents of each signal output from the AC decoding unit 17, confirms that the “start flag signal” certainly indicates “emergency breaking news”, and “emergency breaking news identification signal”. The emergency warning is classified into whether it is an emergency earthquake warning (earthquake motion warning) or an emergency warning broadcast.

  If it is not confirmed that the “activation flag signal” is “0” (there is an emergency warning), the subsequent processing is suspended and the activation flag is continuously monitored.

  Subsequently, when the emergency early warning is emergency warning broadcast, the information processing unit 18 makes the one-segment receiver receive all signals in the partial reception segment and fix them so that all the receivers of the digital terrestrial television broadcast function. The receiver outputs a control signal for starting an operation of receiving signals of all segments. On the other hand, the information processing unit 18 reads all information decoded by the AC decoding unit 17 and issues a necessary warning to the warning generating unit 5 based on the read information when the emergency early warning is an emergency earthquake early warning. The control signal is output.

  The information processing unit 18 reads, for example, “strong earthquake area with seismic intensity 4 or higher” from the decoded “emergency breaking information”, and the position information detected by the position detection unit matches the “strong earthquake area with seismic intensity 4 or higher”. Then, a control signal to that effect is output to the warning generation unit 5.

  The information processing unit 18 reads, for example, “earthquake occurrence time”, “latitude of the epicenter”, “longitude of the epicenter”, “depth of the epicenter”, and “magnitude” from the decoded “emergency breaking information”, and the position With reference to the position information detected by the detector, the calculation based on the equation (6) is performed to calculate the predicted value of the measured seismic intensity. Further, with reference to the position information detected by the position detection unit and the current time information detected by the current time detection unit, the predicted arrival time of the main motion is calculated using a travel time table such as JMA2001, for example.

The position detection unit detects position information indicating a regional position of the receiver. Suitably, a position detection part grasps | ascertains a prefecture area or a wide area by the broadcast provider identification in the "various identification signal" described in message | telegram information. More specifically, in fixed reception, input by a receiver at the time of installation or position detection by GPS (Global Positioning System), in movement or mobile reception, position detection by GPS or base station information in the case of a mobile phone, wireless LAN In this case, the user's own position can be detected by hot spot information (including a manual input of the location if the location can be recognized).
Also, the identification of the broadcaster not only enables identification of the broadcast area, but can add further functions to the receiver. For example, even when an AC signal is received in a normal time without an earthquake early warning regardless of when the earthquake early warning is received, the terrestrial digital television according to the information on the broadcasting area determined by the broadcaster identification is used. A function for automatically setting the channel setting of the broadcast wave can be provided.

  The current time detection unit detects current time information indicating the current time of the receiver. Preferably, the current time detection unit includes time setting by input of a receiver, standard radio wave (radio clock, JJY), GPS, or TDT (Time Date Table) included in a received signal of a received digital terrestrial broadcast wave or Current time information can be detected from TOT (Time Offset Table) or the like. Alternatively, the current time detection unit can detect the current time based on a signal from the base station when the receiver is provided in a mobile phone.

  The warning generation unit 5 displays characters on a display provided in the receiver, generates sound from a speaker provided in the receiver, issues a vibration warning by a vibrator provided in the receiver, or during normal operation. Perceptually generate warnings with different actions. Alternatively, when the receiver is provided in any device such as a mobile phone, a personal digital assistant (PDA), a wristwatch, a table clock, a personal computer, etc., the sound is generated from a speaker using the function of these devices. Alternatively, a vibration warning by a vibrator may be issued, or a warning may be generated perceptually by an operation different from that during normal operation.

  Here, the interframe intermittent reception mode and the intraframe intermittent reception mode will be described.

  In the receiver using the AC signal according to the present invention, the intra-frame intermittent reception mode and the inter-frame intermittent reception mode can be suitably used. The inter-frame intermittent reception mode is more suitable for increasing the reliability of the received signal, and the intra-frame intermittent reception mode is more preferable for increasing the reliability of AC signal synchronization establishment. It is also possible to use the inter-frame intermittent reception mode and the intra-frame intermittent reception mode in combination. By using these intermittent reception modes, the receiver of the present invention can significantly reduce power consumption.

  The inter-frame intermittent reception mode is determined, for example, when emergency early warning synchronization establishment information indicating that AC signal synchronization is not established is supplied. In this case, the ON duration of the first power switch 7 or the second power switch 8 is at least one frame or more. For example, when only one frame is used, the power consumption of the receiver can be greatly reduced. Furthermore, for example, when two frames are used, the reliability of the received signal can be improved by using even parity. Alternatively, for example, when 3 frames are used, it is possible to improve the reliability of the received signal by making a majority decision.

  When the transmission mode of terrestrial digital television broadcasting is mode 3 and the guard interval ratio (GI ratio) is 1/8, one frame is 231.336 msec. Further, in the inter-frame intermittent reception mode, there is no restriction on the power-on timing of the AC reception / synchronization establishment unit 2, and for example, the on / off interval is set to a predetermined value (for example, 10 seconds).

  In this way, by setting the power supply time to the AC reception / synchronization establishing unit 2 when the synchronization of the AC signal is not established to be one frame or more, it is possible to prevent the AC signal from being missed, and further, the AC information analysis The reliability of the received signal in the unit 3 can be improved. Further, standby power consumption can be reduced by increasing the on / off interval.

  The intra-frame intermittent reception mode is determined, for example, when emergency early warning synchronization establishment information indicating that AC signal synchronization is established is supplied. In this case, the ON duration of the first power switch or the second power switch is set to, for example, 20.4112 msec = (18/204) frame as shown in the message information format of FIG. Power is turned on from the last symbol of the previous frame of the signal, and the power is turned off when reception of a required bit, for example, a known signal is completed.

  Alternatively, if the frame synchronization holding unit 19 is in a state in which a certain degree of accuracy can be maintained, the period of the frame for detecting the coincidence of the “synchronization signal” is extended, and the power supply time for the other frames is set to the “synchronization signal”. The last bit and the “activation flag signal” bit 2.268 msec = (2/204) frame. That is, only 2 bits necessary for differential demodulation (based on the equation (5)) are monitored.

  Thus, the standby power consumption can be reduced by setting the power supply time to the AC reception / synchronization establishing unit 2 at the time of establishing the synchronization of the AC signal to 18 symbols or 2 symbols.

  When it is necessary to consider the rising operation of an AGC (automatic gain control) circuit or the like not shown in FIG. 3, the power is turned on earlier by a corresponding time. Further, in the operation of the FFT 11 and the start flag demodulating unit 13, when it is necessary to hold in a memory for a certain symbol, the power is turned on and the power is cut off between the frequency converting unit 9 and the AD converting unit 10 and subsequent processing units. By shifting the timing, it is possible to save the operation of the preceding processing unit with high power consumption.

  Here, the power saving algorithm in the in-frame intermittent reception mode for reducing the standby power consumption of the activation flag signal monitoring will be described in more detail.

  FIG. 4 is an example of a power saving algorithm in the intra-frame intermittent reception mode of the activation flag signal monitoring in the receiver according to the first embodiment of the present invention.

  The receiver according to the first embodiment of the present invention sets the frequency of the terrestrial digital television broadcast wave to be received after the power is turned on (S1). Accordingly, the local oscillation frequency of the frequency conversion unit 9 is changed, and a required intermediate frequency signal is input to the AD conversion unit 10.

  Then, through the FFT 11 and the AC extraction unit 12, frame synchronization is established by detecting coincidence with the synchronization signal multiplexed on the AC signal (S2).

  After that, it becomes a step (S3) of monitoring the activation flag signal, and on / off of the power source detected including the synchronization signal for each designated Nf frame (Nf is an integer), a part of the synchronization signal between them and the activation flag The following operation is performed by repeatedly turning on / off the power source for detecting only the signal (see FIG. 2B).

  The activation flag monitoring unit 21 monitors in every frame whether or not there is an emergency warning indicated by the activation flag signal (S4), and in a normal state (a state in which no emergency warning is issued continues), for each frame, FIG. A frame counter (not shown) counts the value of the frame (n ++, increments the value of the integer n by 1) and returns to n = 0 each time Nf is reached, while the power supply control unit 22 redetects the synchronization signal. The first power switch 7 for switching the power supply to the AC reception / synchronization establishment unit 2 is turned on / off (S5).

  When the activation flag monitoring unit 21 detects that the value of the activation flag signal is emergency warning, the power supply control unit 22 always turns on the first power switch 7 while switching the power supply to the AC information analysis unit 3. The second power switch 8 is turned on, the full text information is read, and error correction is performed based on the parity bit (S6).

  As a result, when the value of the read activation flag signal indicates the emergency early warning again (S7), it is identified whether the emergency early warning is an emergency earthquake warning (EEW) or an emergency warning broadcast (EWS) (S8). In the case of emergency warning broadcasting, as described above, the information processing unit 18 passes through another control unit (not shown) so that all receivers for digital terrestrial television broadcasting function, and the one-segment receiver receives partial reception. All the signals in the segment and the receiver for fixed use start the operation of receiving the signals of all the segments (S9).

  On the other hand, in the case of earthquake early warning, the information processing section 18 promptly displays the information on the warning generation section 5 (S10).

  When the read activation flag signal value does not reproduce the presence of the emergency warning, the activation flag signal monitoring state in the intra-frame intermittent reception mode is restored (S7).

  FIG. 2B shows an example of power supply operation when the above-described power saving algorithm is implemented. In the above algorithm, the activation flag is monitored every frame, while the synchronization signal is monitored only every Nf frame. Therefore, it can be seen that the power consumption related to the monitoring of the synchronization signal can be greatly saved. Furthermore, since the synchronization signal and the activation flag signal are arranged adjacent to each other, the loss of the power supply rise can be reduced.

  As described above, according to the present invention, it is possible to monitor the activation flag signal while saving the power consumption of the receiver, and the emergency early warning is issued, the time when the broadcasting station puts on the radio wave, and the difference between the transmission and reception timings. Even if it is taken into consideration, it is possible to transmit an emergency early warning in a short time of about 1 to 2 seconds.

  A receiver according to Embodiment 2 of the present invention will be described.

  The receiver according to the second embodiment of the present invention is a case where synchronous detection of an AC carrier is performed.

  On the transmission side, as telegram information including emergency early warning, for example, a synchronization signal and an activation flag signal for identifying emergency early warning are continuously transmitted to eight AC carriers in a partial reception segment of digital terrestrial television broadcasting, An emergency early warning identification signal, various identification signals, emergency early warning information, a reserve bit, and a parity bit of an error correction code are transmitted. In the first embodiment, the AC carrier is transmitted as a DBPSK modulated wave. However, in the second embodiment, the AC carrier is transmitted as a BPSK modulated wave except for the synchronization signal.

  The receiver according to the second embodiment of the present invention receives the same telegram information format as the first embodiment of the present invention (the telegram information format shown in FIG. 2A). Here, the receiver can be included in any device such as a mobile phone, a personal digital assistant (PDA), a wristwatch, a table clock, a personal computer, or a home appliance.

  FIG. 5 is a block diagram of a receiver according to the second embodiment. The receiver according to the second embodiment includes an antenna 1, an AC reception / synchronization establishment unit 2, an AC information analysis unit 3, a synchronization holding / power control unit 4, a warning generation unit 5, a power source 6, an AC reception / The first power switch 7 for switching the power supply to the synchronization establishment unit 2 and the second power switch 8 for switching the power supply to the AC information analysis unit 3, and the receiver of the first embodiment It has the same configuration.

  The difference from FIG. 3 is in the AC reception / synchronization establishment unit 2, that the SP extraction unit 25 is provided after the FFT 11, and that the propagation path estimation unit 23 and the interpolation filter 24 are included in this SP extraction unit 25. It continues.

The SP extraction unit 25 extracts only the SP carrier in the partial reception segment (segment number # 0) from the OFDM format stream of the reception signal. As described above, in the ISDB-T terrestrial digital television broadcast, the SP signal p (l, k) whose amplitude and phase values are known is transmitted together with the data. The SP signals are arranged at intervals of 12 carriers for each symbol, and the positions of consecutive symbols are shifted by 3 carriers and repeated every 4 symbols. Further, the phase value is determined by the carrier number k, and is the value of W _k (value based on the generator polynomial x ¹¹ + x ⁹ +1) described in the above-mentioned differential demodulation standard of the telegram information format. It is multiplexed as a wave.

  The SP carrier extracted by the SP extraction unit 25 is supplied to the propagation path estimation unit 23.

The propagation path estimator 23 receives SP signals for 4 symbols multiplexed by the partial reception segment (segment number # 0) of the terrestrial digital television broadcast wave of, for example, ISDB-T system extracted by the SP extractor 25. The calculation based on the equation (1) using the signal and the BPSK modulated wave by the value of W _k is performed, and the propagation path characteristic in each obtained SP carrier is calculated and output.

  The interpolation filter 24 is an FIR for calculating a value interpolated from a plurality of propagation path characteristics at the SP carrier position in order to obtain propagation path characteristics of the AC carrier and symbol position in which the activation flag signal is stored. It is a filter.

  Then, instead of calculating the phase change between the AC carrier synchronization signal and the activation flag signal, the activation flag demodulator 13 interpolates the reception signal of the activation flag signal stored in the AC signal extracted from the AC extraction unit 12 and the interpolation. The activation flag signal is demodulated by performing multiplication with the phase conjugate of the interpolated interpolation value of the propagation path characteristic in the same carrier and symbol output from the interpolation filter 24.

  The following operation is the same as that of the receiver according to the first embodiment of the present invention.

  The receiver according to the second embodiment of the present invention has a slightly complicated circuit configuration as compared with the receiver according to the first embodiment of the present invention. However, since the synchronous detection of the BPSK modulation wave is performed, the maximum ratio combining is performed. Therefore, it is possible to detect the activation flag signal with higher sensitivity and to receive the emergency early warning.

  In the above description, a transmission example including information on emergency warning performed using an AC carrier has been introduced. However, it is also possible to apply only an alarm to a reserve bit of a TMCC signal or the like.

  Although the specific coding scheme has been described as a representative example for the above-described embodiments, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. For example, in the above-described embodiment, in order to facilitate understanding of the present invention, it has been described that the receiver according to the present invention can be provided in, for example, a mobile phone. In addition, the function of the receiver according to the present invention can be integrated into the decoding function. For example, when the mobile phone is in the standby mode, it can be operated in the same manner as in the above-described embodiment. Alternatively, when the mobile phone is in the normal operation mode, the flag value in the telegram information is set. Depending on the determination, the emergency early warning may be decoded without performing power supply control, the seismic intensity and arrival time prediction information for the area where the mobile phone is located may be calculated, and a warning may be issued. Accordingly, the invention should not be construed as limited by the embodiments described above, but only by the claims.

  Since the receiver according to the present invention enables rapid and reliable transmission of emergency earthquake early warning, it is useful for the application of a transmission system using a predetermined transmission control signal.

DESCRIPTION OF SYMBOLS 1 Antenna 2 AC reception / synchronization establishment part 3 AC information analysis part 4 Synchronization holding | maintenance / power supply control part 5 Alarm generation part 6 Power supply 7 1st switch 8 2nd switch 9 Frequency conversion part 10 AD conversion part 11 FFT
12 AC extraction unit 13 activation flag demodulation unit 14 frame synchronization detection unit 15 AC demodulation unit 16 error correction unit 17 AC decoding unit 18 information processing unit 19 frame synchronization holding unit 20 timing control unit 21 activation flag monitoring unit 22 power supply control unit 23 propagation Path estimation unit 24 Interpolation filter 25 SP extraction unit

Claims (5)

A receiver for receiving a transmission control signal from a terrestrial digital television broadcast wave,
Telegram information including a synchronization signal for recognizing the frame length of the transmission control signal and performing frame synchronization, and a flag that is arranged subsequent to the synchronization signal and that identifies the presence or absence of emergency early warning is transmitted from the transmission side. It is pre-defined to be transmitted with a control signal,
Frame synchronization means for receiving a carrier of the transmission control signal and performing frame synchronization based on a synchronization signal included in the transmission control signal;
Frame synchronization holding means for holding frame synchronization timing for a certain period after frame synchronization;
Flag demodulation means for demodulating the flag from the carrier of the received transmission control signal;
Flag monitoring means for monitoring the value of the flag arranged immediately after the synchronization signal;
When both synchronization establishment and flag monitoring are performed, power is supplied to the frame synchronization means and flag demodulation means in accordance with the reception timing of the synchronization signal and flag, and when flag monitoring is performed after synchronization is established, reception of the flag Power supply control means for supplying power to the flag demodulation means in accordance with the timing,
The power supply control means supplies power to the flag demodulation means in accordance with the last bit of the synchronization signal and the reception timing of the flag when flag monitoring is performed after synchronization is established.   2. The power supply control unit according to claim 1, wherein the power control unit supplies power intermittently between a plurality of frames with respect to the reception timing of the synchronization signal and the flag when both synchronization establishment and flag monitoring are performed. Receiving machine.   The receiver according to claim 2, wherein the flag monitoring means makes a majority decision using the plurality of flags received between the plurality of frames.   The receiver according to any one of claims 1 to 3, wherein the flag demodulating means delay-detects the flag with reference to the last bit of the synchronization signal. The carriers are eight AC carriers in the ISDB-T system of terrestrial digital television,
The receiver according to any one of claims 1 to 4, wherein the flag monitoring means synthesizes and monitors the flags received from the eight AC carriers in order to obtain a diversity gain. .

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