JP2007324953A - Device and method for acquiring vbi data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for acquiring VBI data by which the VBI data are surely acquired even if TV broadcast in which a start point of a VBI signal is different from general standards is received. <P>SOLUTION: When a TV signal including the VBI data is received from a broadcasting station, the acquisition start timing of the VBI data is determined. First, an initial value of the acquisition start timing is set, and next, a lower limit value of the acquisition start timing is set. Then, an error rate of the VBI data in each acquisition start timing is detected while shifting the acquisition start timing from the initial value to the lower limit value. Then, the acquisition start timing in which the error rate become the lowest is determined as the acquisition start timing of the subsequent VBI data. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a VBI data acquisition apparatus and a VBI data acquisition method for acquiring VBI data from a VBI signal, and in particular, properly acquires VBI data even when a horizontal shift of the start position of the VBI signal occurs. The present invention relates to a VBI data acquisition apparatus and a VBI data acquisition method.

  Conventionally, in analog television broadcasting, as a service for transmitting additional information (VBI data) superimposed on a signal (VBI signal) in a vertical blanking interval (VBI) of a TV signal (television signal), Character multiplex broadcasting, data multiplex broadcasting, etc. are being implemented. First, an example of a VBI data transmission mode will be briefly described.

  First, signals included in VBI will be described. An interlace system is adopted for NTSC (National Television System Committee) TV signals that have been widely used in Japan. According to this, one frame image composed of 525 horizontal scanning lines is divided into a field image composed of odd-numbered horizontal scanning lines of 525 horizontal scanning lines and a field composed of even-numbered horizontal scanning lines. It consists of images. Therefore, one field image has 262.5 horizontal scanning lines.

  Of the 262.5 horizontal scanning lines of this field image, the first to 21st lines are called VBI and are areas not containing video signals. A vertical synchronizing signal is recorded in the data area of the first to ninth horizontal scanning lines in the VBI. The remaining data areas of the 10th to 21st horizontal scanning lines are areas where VBI data can be transmitted.

  As a broadcast service using VBI, for example, there is a service that performs data transmission by the ADAMS method or the bitcast method in the data area of the tenth to thirteenth horizontal scanning lines. In this service, for example, EPG (Electronic Program Guide) data is transmitted using the data area. The data areas of the 14th to 16th and 21st horizontal scanning lines are used as areas for transferring data for teletext.

  FIG. 4 shows an example of a TV signal that carries VBI data. As shown in FIG. 4, the portion where the VBI data is coded (hereinafter referred to as “VBI signal 93”) includes the horizontal sync signal 91 and the color burst signal 92 of the TV signal, and the next incoming horizontal sync signal 91 ′. Located between. The vertical synchronization signal 91 is a signal for measuring the timing in the horizontal direction when the electron gun draws a screen in the TV apparatus. The color burst signal 92 is a signal inserted immediately after the horizontal synchronization signal in the NTSC TV signal. The color burst signal 92 is a synchronization signal serving as a hue reference for color reproduction.

  The normal VBI signal 93 is defined in the standard so as to start about 9.7 μsec (point C in FIG. 4) after the fall of the horizontal synchronizing signal 91 (point A in FIG. 4). Note that the end of the color burst signal 92 is defined by the standard so as to be approximately 8.0 μsec after the falling edge of the horizontal synchronizing signal 91 (point B in FIG. 4).

  In relation to the data transfer technology using VBI as described above, Patent Document 1 discloses a data transmission apparatus capable of efficiently transmitting a character multiplexed TV signal in a narrow band and receiving it with an analog receiver. Is disclosed. The data transmission apparatus of Patent Document 1 encodes and transmits VBI data together with line number information of a video signal on which the VBI data is superimposed. Then, the VBI data decoded on the receiving side is incorporated into the video signal in accordance with the line number to generate a standard format TV signal. This makes it possible to effectively use the transmission band and receive VBI data with the analog receiver.

Further, Patent Document 2 discloses an information recording / reproducing apparatus capable of searching for an arbitrary part in a program by recording VBI data existing in VBI in association with AV data to be recorded. . The information recording / reproducing apparatus described in Patent Document 2 records AV data included in a TV signal, extracts additional information existing in the VBI, and records the extracted additional information in association with the AV data. The recorded additional information can be searched by a search function, and recorded AV data can be reproduced in accordance with the search result. This makes it possible to easily search for an arbitrary part in the program.
JP 2004-064461 A JP 2002-199338 A

  However, the start point of the VBI signal is determined by the standard to be approximately 9.7 μsec after the falling edge of the horizontal synchronization signal, but the timing is actually different for each broadcasting station. Therefore, there is a case where a TV signal whose start point of the VBI signal is earlier or later than the standard value (after about 9.7 μsec) is used for TV broadcasting.

  According to the above-described conventional apparatus, the VBI signal acquisition timing is set to a fixed value (for example, the standard value) for each apparatus. Therefore, when the start point of the VBI signal included in the received TV signal is earlier than a fixed value (for example, 9 μs after the falling edge of the horizontal synchronization signal), there is a problem that acquisition of VBI data fails. .

  An object of the present invention is to provide a VBI data acquisition apparatus and a VBI data acquisition method capable of reliably acquiring VBI data even when a TV broadcast having a VBI signal starting point different from a general standard is received.

  In order to achieve the above object, a VBI data acquisition apparatus of the present invention is generated in a receiving means for receiving a television signal, an extracting means for extracting VBI data existing in the VBI of the television signal, and the extracting means. A VBI data acquisition apparatus comprising failure rate calculation means for calculating an acquisition failure rate of the VBI data, wherein the extraction means acquires the VBI data from a falling edge of a horizontal synchronization signal included in the television signal. A parameter setting unit that represents a time difference to a start point using a parameter; an initial value setting unit that sets an initial value of the parameter; a lower limit value setting unit that sets a lower limit value of the parameter; and the parameter that is the initial value Step of executing the extraction means and the failure rate calculation means while decreasing the value from the lower limit value to the lower limit value for each constant value And parts, are characterized in that a starting point determining unit that determines an acquisition start point of the VBI data based on the parameter in which the acquisition failure rate becomes minimum at the stage execution unit.

  According to this, when a TV signal (TV signal) including VBI data is received from a broadcast station, processing for determining the acquisition start timing of VBI data is performed. First, an initial value for the acquisition start timing is set, and then a lower limit value for the acquisition start timing is set. Then, the error rate (acquisition failure rate) of the VBI data at each acquisition start timing is detected while shifting the acquisition start timing from the initial value toward the lower limit (changes for every fixed value). Then, the acquisition start timing at which the error rate is the lowest is determined as the subsequent VBI data acquisition start timing.

  In order to achieve the above object, the VBI data acquisition apparatus according to the present invention is configured such that the initial value setting unit sets an initial value of the parameter to a standard value of 9.7 μsec, and the lower limit value setting unit. The lower limit value of the parameter is set to 8.0 μsec, which is the time difference from the fall of the horizontal synchronization signal to the end of the color burst signal.

  According to this, the initial value of the acquisition start timing is 9.7 μsec after the falling edge of the horizontal synchronization signal, which is the start timing defined by the VBI data standard. As the lower limit, the end of the color burst signal (8.0 μsec after the falling edge of the horizontal synchronization signal) is used.

  In order to achieve the above object, the VBI data acquisition apparatus according to the present invention is configured such that when the start point determination unit determines that the acquisition failure rate is constant even if the parameter changes, The acquisition start point of the VBI data is determined based on the value.

  According to this, when there is no change in the error rate even when the acquisition start timing is shifted (the error rate is constant), the initial value (after 9.7 μsec) of the acquisition start timing is used as the subsequent VBI data. Is determined as the acquisition start timing.

  The start point determination unit subtracts a constant value from the parameter corresponding to the minimum acquisition failure rate, and determines the acquisition start point of the VBI data based on the value calculated by the subtraction. It is said.

  According to this, the timing (timing near the end of the color bust signal) slightly earlier than the acquisition start timing at which the error rate is minimized is determined as the subsequent VBI data acquisition start timing.

  According to the present invention, the error rate of the VBI data at each acquisition start timing is detected while shifting the acquisition start timing from the initial value toward the lower limit value. Then, the acquisition start timing at which the error rate is the lowest is determined as the subsequent VBI data acquisition start timing. This makes it possible to acquire data from the timing with the lowest error rate of VBI data. For this reason, even if the VBI data is started at a timing different from the standard, it is possible to reliably acquire the VBI data.

  Further, according to the present invention, the initial value of the acquisition start timing is 9.7 μs after the falling edge of the horizontal synchronization signal, which is the start timing defined by the VBI data standard. Further, the end of the color burst signal is used as the lower limit value. Thereby, it is possible to check all the timings that can be assumed as the start point of the VBI signal, and it is possible to more reliably determine the acquisition start timing.

  In addition, according to the present invention, when there is no change in the error rate even if the acquisition start timing is shifted, the initial value of the acquisition start timing is determined as the subsequent VBI data acquisition start timing. Thereby, even when the start timing of VBI data is later than the standard value (for example, after 10 μs), it is possible to reliably acquire VBI data.

  Further, according to the present invention, a timing slightly earlier than the acquisition start timing at which the error rate is minimized is determined as the subsequent VBI data acquisition start timing. Thereby, since acquisition of VBI data is started at a timing slightly earlier than the timing at which actual VBI data is started, it is possible to acquire VBI data more reliably.

  Hereinafter, the VBI data acquisition process in the TV receiver 10 of the present invention will be described with reference to the drawings. In addition, embodiment shown here is an example and this invention is not limited to embodiment shown here.

<1. Concerning Main Configuration of TV Receiver>
Here, the configuration of the main part of the TV receiver 10 of the present invention will be described in detail with reference to the drawings. FIG. 2 is a schematic configuration diagram of the apparatus. As shown in FIG. 2, the TV receiving apparatus 10 includes an antenna 1, a receiving unit 2, a detection circuit 3, a VBI data extracting unit 4, a slice level adjusting unit 5, a time measuring unit 6, a storage unit 7, a control unit 8, and the like. ing.

  The TV signal received by the antenna 1 is transmitted to the receiving unit 2. The receiving unit 2 has a tuner circuit or the like for selecting a signal having a desired frequency, performs predetermined processing on the received signal, and outputs it to a subsequent circuit (receiving means).

  The detection circuit 3 extracts the video signal and the audio signal from the input signal and outputs them to the subsequent circuit. The subsequent circuit outputs video and audio based on these signals.

  The VBI data extraction unit 4 is a circuit for extracting VBI information from an input signal and outputting it to a subsequent circuit (extraction means). Specifically, the VBI signal included in the input signal and the slice level determined by the slice level adjusting unit 5 are compared in accordance with the timing indicated by a predetermined sampling pulse. Then, digital data related to the VBI signal is extracted according to the magnitude relationship between the two. In the subsequent circuit, VBI information is provided to the user based on the extracted VBI data. The VBI data extraction unit 4 has a function of detecting an error rate (data acquisition failure rate) of the extracted digital data (failure rate calculation means). The detected error rate is notified to the control unit 8 at the subsequent stage.

  The slice level adjustment unit 5 is a circuit for adjusting the slice level used in the VBI data extraction unit 4 to an appropriate level. The slice level adjustment unit 5 appropriately adjusts the slice level so that the VBI data can be extracted correctly even if the received signal is distorted by noise such as ghost.

  The time measuring unit 6 continuously measures the current time by using, for example, a crystal oscillator or a frequency dividing circuit. The current time information is used to adjust the acquisition start timing of a series of VBI signals. The current time information may be used to notify the user of the time through the display means.

  The storage unit 7 is a storage medium that stores VBI data transmitted from a broadcasting station, various information (timing information used in a processing flow described later), and the like used for VBI data acquisition processing and the like.

  The control unit 8 is a central processing unit for performing overall control of video reception processing or VBI data acquisition processing by organically controlling driving of each member of the TV receiving device 10. The control unit 8 is a central part that controls each device (for example, the storage unit 7 and the like), calculates data, processes, and the like.

<2. How to obtain VBI data>
Here, a method of acquiring VBI data in the TV receiver 10 of the present invention will be described with reference to the flowchart of FIG. 1, the block diagram of FIG. 2, and the explanatory diagram of FIG. FIG. 3 is an explanatory diagram schematically showing FIG. 4, and the same reference numerals (points A to C) indicate the same contents as FIG. 4. In FIG. 3, a range α indicates a range in which the VBI signal may exist. A range β indicates a range where no VBI signal exists (because the color burst signal 92 and the like exist). A range γ indicates a range where the start point of the VBI signal may exist.

  FIG. 1 is a flowchart showing a processing flow of the VBI data acquisition processing of the present invention. The processing shown in FIG. 1 is started when the control unit 8 receives a data broadcast including a VBI signal using the antenna 1 and the receiving unit 2. The control unit 8 that has received the data broadcast sets a parameter indicating the acquisition start timing of the VBI signal. This parameter is a numerical value representing the time difference from the fall of the horizontal synchronization signal to the acquisition start timing. A standard value (9.7 μsec, point C in FIG. 3) is set as an initial value for the parameter (step S110). Therefore, step S110 constitutes a parameter setting unit and an initial value setting unit for setting and initializing parameters.

  Next, the control unit 8 sets the end of the color burst signal 92 (8.0 μs, point B in FIG. 3) as the lower limit value of the parameter (step S120). Accordingly, step S120 constitutes a lower limit value setting unit that sets the lower limit value of the parameter at 8.0 μsec.

  The control unit 8 extracts the VBI signal from the TV signal using the VBI data extraction unit 4 and the VBI signal acquisition start timing indicated by the parameter. The extracted VBI signal is converted into VBI data. At this time, the VBI data extraction unit 4 calculates a data acquisition failure rate (error rate) at the time of data conversion, and notifies the control unit 8 (step 130).

  The control unit that has received the notification of the error rate stores it in the storage unit 7 (step S140). Then, the parameter is subtracted by a predetermined value (for example, 0.1 μsec) (step S150).

  Next, the controller 8 checks whether or not the parameter value is below the lower limit value set in step S120 (8.0 μs in this example) (step S160). If not lower (the acquisition start timing is within the range γ in FIG. 3), the process proceeds to step 130. In this manner, the acquisition start timing is shifted stepwise by repeatedly performing the processing from step S130 to step S160 (arrow S in FIG. 3). The error rate at each timing is calculated and stored while shifting. Accordingly, steps S130 to S160 constitute a stage execution unit that calculates the error rate while changing the parameters in stages.

  When the parameter value falls below the lower limit value in step S160, the control unit 8 completes the series of error rate acquisition processes. Then, the error rate for each acquisition start timing stored in the storage unit 7 is confirmed. Then, it is determined whether there is a change in the error rate accompanying the change in acquisition start timing (step S170).

  If there is a change in the error rate, the parameter value at the point where the error rate is minimized is acquired (step S180, point D in FIG. 3). Then, a predetermined constant value (for example, 0.05 μsec) is subtracted from the parameter. As a result, the point indicated by the parameter is determined as the acquisition start timing (step S190, point E in FIG. 3). However, if the result of subtraction is less than the lower limit value, the lower limit value is substituted into the parameter, and the point indicated by the lower limit value is determined as the acquisition start timing (point B in FIG. 3).

  Conversely, if there is no change in the error rate (the error rate is constant at any acquisition start timing), the initial value (9.7 μsec) is substituted for the parameter. Thereby, a point determined in advance by the standard is determined as an acquisition start timing (step S190a, point C in FIG. 3). Accordingly, steps S170 to S190a constitute a start point determination unit that determines the acquisition start point of the VBI signal based on the error rate calculated by the stage execution unit including steps S130 to S160.

  Next, the control unit 8 stores the acquisition start timing of the VBI signal obtained in Step 190 or Step 190a in the storage unit 7 (Step S200).

  Then, based on the stored VBI signal acquisition start timing, VBI data acquisition is executed (S210). Normally, the start timing of the VBI signal in each TV signal is the same unless the broadcast station of the received data broadcast is changed. Therefore, once the VBI signal acquisition timing is determined, the value can be continuously used as long as there is no change in the broadcasting station.

[Other embodiments]
The present invention has been described with reference to the preferred embodiments and examples. However, the present invention is not necessarily limited to the above embodiments and examples, and various modifications may be made within the scope of the technical idea. Can be implemented.

  For example, a storage medium in which a program code of software that realizes the functions of the above-described embodiments is recorded in a video processing apparatus having a data broadcast reception function other than the TV apparatus reception apparatus, and the program code stored in the storage medium Needless to say, this can also be achieved by reading out and executing.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code and the communication terminal mounted with the storage medium constitute the present invention. become.

  As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a magnetic tape, a nonvolatile memory card, or the like can be used.

  Further, as a video processing apparatus having a data broadcast receiving function other than the TV receiving apparatus, for example, a video recorder, HDD recorder, DVD recorder, reception tuner, car navigation system, mobile phone, or the like can be used.

  In the above-described embodiment, the acquisition start timing of the VBI signal is acquired based on the received data broadcast. Basically, the start point of the VBI signal is different if the broadcasting station is different. Therefore, in practice, it is necessary to perform the acquisition start timing determination process described above every time a broadcasting station detects different radio waves. Note that the VBI signal acquisition start timing may be stored for each broadcast station. In this case, the broadcast station may be determined from the received radio wave, and the VBI signal may be acquired using the acquisition start timing corresponding to each broadcast station from the stored acquisition start timings.

  Further, in the above-described embodiment, the error rate is measured while changing the parameter in the range γ in FIG. 3, but actually, the VBI signal start point is later than the point C (the right direction of the point C). ). However, since the point C is set as the upper limit of the VBI data acquisition start point in step S190a, it is possible to avoid a VBI signal acquisition error even in the above case.

  In the above-described embodiment, the constant value is subtracted from the parameter in step S190. This is a process for giving a margin to the acquisition start timing in order to reliably acquire the VBI signal. Therefore, step S190 is not necessarily executed, and may be omitted depending on the accuracy of the required acquisition start timing.

  In the embodiment described above, the subtraction values in step S150 and step S190 are merely examples. It goes without saying that the same effects as those of the present invention can be obtained even if the above processing is performed using values other than this.

It is the flowchart which showed the processing flow of the VBI data acquisition apparatus of this invention. It is the block diagram which showed the principal part structure of the electric circuit of the VBI data acquisition apparatus of this invention. It is explanatory drawing for demonstrating the content of the error rate acquisition process of the VBI data acquisition apparatus of this invention. It is explanatory drawing for demonstrating the structure of the TV signal in the conventional VBI.

Explanation of symbols

1 Antenna (reception means)
2 Receiver (Receiving means)
3 Detection circuit 4 VBI data extraction unit (extraction means)
5 Slice Level Adjustment Unit 6 Timekeeping Unit 7 Storage Unit 8 Control Unit 10 TV Receiver 91 Horizontal Sync Signal 92 Color Burst Signal 93 VBI Signal

Claims (10)

Receiving means for receiving a television signal;
Extracting means for extracting VBI data present in the VBI of the television signal;
A failure rate calculating means for calculating an acquisition failure rate of the VBI data generated in the extracting means;
A VBI data acquisition device comprising:
In the extraction means, a parameter setting unit that represents a time difference from a falling edge of a horizontal synchronization signal included in the television signal to an acquisition start point of the VBI data using a parameter;
An initial value setting unit for setting an initial value of the parameter to a standard value of 9.7 μsec;
A lower limit value setting unit for setting the lower limit value of the parameter to 8.0 μsec, which is the time difference from the falling edge of the horizontal synchronization signal to the end of the color burst signal;
The extraction unit and the failure rate calculation unit are executed while the parameter is decreased from the initial value to the lower limit value by a certain value, and each acquisition failure rate is stored in the storage unit in association with the parameter. A stage execution unit;
The minimum acquisition failure rate is determined from the acquisition failure rates stored in the storage unit, the parameter corresponding to the minimum acquisition failure rate is read, and VBI data is read based on the read parameter. A start point determination unit for determining the acquisition start point of
Providing
The start point determination unit determining the acquisition start point of the VBI data based on the initial value of the parameter when it is determined that the acquisition failure rate is constant even if the parameter is changed; ,
In the starting point determination unit, a constant value is subtracted from the parameter corresponding to the minimum acquisition failure rate, the value calculated by the subtraction is compared with the lower limit value, and the value is calculated based on the larger value. Determining the acquisition start point of VBI data;
A VBI data acquisition apparatus characterized by the above. Receiving means for receiving a television signal;
Extracting means for extracting VBI data present in the VBI of the television signal;
A failure rate calculating means for calculating an acquisition failure rate of the VBI data generated in the extracting means;
A VBI data acquisition device comprising:
In the extraction means, a parameter setting unit that represents a time difference from a falling edge of a horizontal synchronization signal included in the television signal to an acquisition start point of the VBI data using a parameter;
An initial value setting unit for setting an initial value of the parameter;
A lower limit setting unit for setting the lower limit of the parameter;
A step execution unit that executes the extraction unit and the failure rate calculation unit while decreasing the parameter from the initial value to the lower limit value for each constant value;
A start point determination unit for determining an acquisition start point of the VBI data based on the parameter having the smallest acquisition failure rate in the stage execution unit;
A VBI data acquisition apparatus comprising: In the initial value setting unit, setting an initial value of the parameter to a standard value of 9.7 μsec;
In the lower limit value setting unit, setting the lower limit value of the parameter to 8.0 μsec that is a time difference from the fall of the horizontal synchronization signal to the end of the color burst signal;
The VBI data acquisition device according to claim 2. The start point determination unit determines the acquisition start point of the VBI data based on the initial value of the parameter when it is determined that the acquisition failure rate is constant even if the parameter changes. The VBI data acquisition apparatus according to claim 2 or claim 3, wherein The start point determination unit subtracts a constant value from the parameter corresponding to the minimum acquisition failure rate, and determines the acquisition start point of the VBI data based on the value calculated by the subtraction. The VBI data acquisition apparatus according to any one of claims 2 to 4. A receiving process for receiving a television signal;
An extraction step of extracting VBI data present in the VBI of the television signal;
A failure rate calculation step of calculating an acquisition failure rate of the VBI data generated in the extraction step;
A VBI data acquisition method comprising:
A parameter setting unit that represents a time difference from a falling edge of a horizontal synchronization signal included in the television signal to an acquisition start point of the VBI data using a parameter in the extraction step;
An initial value setting unit for setting an initial value of the parameter to a standard value of 9.7 μsec;
A lower limit value setting unit for setting the lower limit value of the parameter to 8.0 μsec, which is the time difference from the falling edge of the horizontal synchronization signal to the end of the color burst signal;
While performing the extraction step and the failure rate calculation step while decreasing the parameter from the initial value to the lower limit value by a certain value, each acquisition failure rate is stored in the storage unit in association with the parameter. A stage execution unit;
The minimum acquisition failure rate is determined from the acquisition failure rates stored in the storage unit, the parameter corresponding to the minimum acquisition failure rate is read, and VBI data is read based on the read parameter. A start point determination unit for determining the acquisition start point of
Having
The start point determination unit determining the acquisition start point of the VBI data based on the initial value of the parameter when it is determined that the acquisition failure rate is constant even if the parameter is changed; ,
In the starting point determination unit, a constant value is subtracted from the parameter corresponding to the minimum acquisition failure rate, the value calculated by the subtraction is compared with the lower limit value, and the value is calculated based on the larger value. Determining the acquisition start point of VBI data;
The VBI data acquisition method characterized by these. A receiving process for receiving a television signal;
An extraction step of extracting VBI data present in the VBI of the television signal;
A failure rate calculation step of calculating an acquisition failure rate of the VBI data generated in the extraction step;
A VBI data acquisition method comprising:
A parameter setting unit that represents a time difference from a falling edge of a horizontal synchronization signal included in the television signal to an acquisition start point of the VBI data using a parameter in the extraction step;
An initial value setting unit for setting an initial value of the parameter;
A lower limit setting unit for setting the lower limit of the parameter;
A step execution unit that executes the extraction step and the failure rate calculation step while decreasing the parameter from the initial value to the lower limit value every fixed value;
A start point determination unit for determining an acquisition start point of the VBI data based on the parameter having the smallest acquisition failure rate in the stage execution unit;
A VBI data acquisition method comprising: In the initial value setting unit, setting an initial value of the parameter to a standard value of 9.7 μsec;
In the lower limit value setting unit, setting the lower limit value of the parameter to 8.0 μsec that is a time difference from the fall of the horizontal synchronization signal to the end of the color burst signal;
The VBI data acquisition method according to claim 7. The start point determination unit determines the acquisition start point of the VBI data based on the initial value of the parameter when it is determined that the acquisition failure rate is constant even if the parameter changes. 9. The VBI data acquisition method according to claim 7, wherein the VBI data is acquired. The start point determination unit subtracts a constant value from the parameter corresponding to the minimum acquisition failure rate, and determines the acquisition start point of the VBI data based on the value calculated by the subtraction. The VBI data acquisition method according to any one of claims 7 to 9.

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