JP2010093509A - Determining method of influence of power transmission steel tower affecting digital terrestrial broadcasting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a logical determining method of specifying at an early stage whether or not a cause for digital electric waves which cannot be received is simple shielding phenomena due to terrain, whether or not the cause is the generation of sneaked waves or whether or not the cause is the generation of scattered waves, and a duration when the cause of reception failure arises and remains. <P>SOLUTION: The method has a step of measuring a reception electric field at each measuring height while changing the measuring height every 50 cm between 4 m and 10 m from ground in a shielding side area 11, and a step of determining that the power transmission steel tower 2 is affecting the digital terrestrial broadcasting when an amount of variation of the reception electric field between adjacent measuring heights is ≥3 dB and the number of generated times is twice or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for determining the influence of a power transmission tower on terrestrial digital broadcasting.

  Conventionally, the generation of sneak waves is known to occur when digital radio waves are reflected by structures such as steel towers or topography. However, when the level is high, digital radio waves cannot be received in a predetermined service area. (Patent Document 1), and as a countermeasure against the specific area where the digital radio wave cannot be received, the digital radio wave from the transmitting station is reflected radially by the curved reflector, and directed toward the specific area. A method for transmitting is known (Patent Document 2).

Japanese Patent Laid-Open No. 2003-329661 JP 2003-298485 A

  However, in the vicinity of the transmission tower, when digital radio waves cannot be received, radio waves are incident on the power transmission equipment, and countless scattered waves are generated from the wires and the transmission tower, affecting the quality of the received radio waves. Is also possible. In addition, it is not clear what effect it may have on radio wave reception due to the complex mechanism of the scattered wave generated from the power transmission tower and the lack of measured data of the scattered wave. In addition, when there are a plurality of buildings or when reception is difficult due to topography, it is difficult to accurately identify the cause of the reception failure. Therefore, in order to take this measure, it is necessary to identify the cause of the inability to receive digital radio waves due to the terrain shielding phenomenon, the occurrence of sneak waves, or the occurrence of scattered waves was there.

  In addition, when a transmission facility is newly installed or changed, it is possible to make a relatively clear judgment on reception failure by investigating the area before construction and comparing it with data after construction. It is. However, terrestrial digital broadcasting is a late phenomenon, and depending on the owner of the power transmission equipment, it may be possible to take measures if there is an effect on the existing equipment. Furthermore, due to legal developments in the future, it is possible that the duty to take countermeasures will be imposed on the installers regardless of when the buildings are installed. In such a case, it has been difficult to clarify the causal relationship between the power transmission equipment and the reception failure.

  Therefore, the present invention solves the above-mentioned conventional problems, whether the cause of the inability to receive digital radio waves in the vicinity of the transmission tower is simply a shielding phenomenon due to landforms, or due to the generation of sneak waves, due to the generation of scattered waves It is an object of the present invention to provide a logical judgment method for identifying at an early stage whether or not the cause of the reception failure has occurred, and the cause of the reception failure.

  In order to achieve the above object, the invention described in claim 1 is a method for determining the influence of a power transmission tower on terrestrial digital broadcasting, wherein a measurement height is changed by a predetermined amount from a predetermined measurement point in a vertical direction. And measuring the received electric field at each measurement height, and when the amount of fluctuation of the received electric field between adjacent measurement heights exceeds a predetermined number of times, the power transmission tower performs terrestrial digital broadcasting. And a step of determining that it is highly likely that the process is affected.

  The invention according to claim 2 is a method for determining the influence of a power transmission tower on terrestrial digital broadcasting, wherein reception at each measurement height is performed by changing the measurement height in a vertical direction from a predetermined measurement point. A step of measuring an electric field and measuring a digital radio wave at the predetermined measurement point when the amount of fluctuation of the received electric field between adjacent measurement heights exceeds a predetermined number of times. There are a step of confirming a sneak wave generated when a radio wave is incident on an obstacle, and a step of judging that an influence by a power transmission tower is generated when the sneak wave is not measured.

  According to a third aspect of the present invention, in addition to the first or second aspect of the invention, in the measuring step, the measurement height is changed every 50 cm between 4 m and 10 m above the ground.

  In addition to the invention of claim 3, the invention of claim 4 is characterized in that, in the step of measuring, when a channel in which the amount of fluctuation of the received electric field is 3 dB or more and the number of occurrences is 2 or more is measured, It is determined that the power transmission tower has an influence on terrestrial digital broadcasting.

  According to the present invention, whether the cause of the inability to receive digital radio waves is due to the occurrence of sneak waves or the occurrence of scattered waves, the cause is identified, and the causal relationship between the transmission tower and reception interference is clarified. It becomes possible. Since the cause is resolved logically at an early stage, effective countermeasures can be taken without taking unnecessary measures against the reception failure. In addition, a logical explanation can be given to the parties or third parties of the radio disturbance, and troubles due to radio disturbance in the area can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram showing the reception status of digital radio waves. FIG. 2 is an explanatory diagram showing a method for measuring digital radio waves. FIG. 3 is an explanatory diagram showing the relationship between the electric field strength and the measured height.

  As shown in FIG. 1, digital radio waves are directly transmitted as direct waves 7, 7, etc., in general houses 6 and 6 in the front area 10 located between the transmitting antenna 1 and the transmitting antenna 1 and the power transmission tower 2. .. and transmitted to the antennas of the ordinary houses 6, 6... In the shielding side area 11 located behind the power transmission tower 2. At this time, a part of the direct waves 8, 8... Is incident on the power transmission tower 2 and the electric wire, thereby generating a scattered wave 9. The scattered wave 9 is received together with the direct wave 7 by the antennas of the general houses 6, 6. For scattered waves 9, 9,... Generated in the front area from the power transmission tower 2, this influence is excluded from the characteristics of the antenna that receives only from a specific direction.

Then, as shown in FIG. 2, the direct wave 8 is measured at the measurement point with the car 3 in the front area 10 of the power transmission tower 2. At this time, the antenna 5 is measured every 1 m at a height of about 4 m to 10 m from the ground. Similarly, the scattered wave 9 is also measured by the antenna 5 in the car 4 in the shielding side area 11.
Moreover, in the shielding side area 11 of the power transmission tower 2, FIG. 3 (a) shows the relationship between the electric field strength and measurement height of the area 20m away from the power transmission tower 2, and FIG. 3 (b) shows the area 60m away. This shows the relationship between the electric field strength and the measured height at.

  As a result, in the front area 10, it is recognized that there is a substantially constant correlation between the electric field strength and the measured height. In this case, at the measurement point in the front area 10 that is not affected by the steel tower, even if the antenna 5 is moved up and down about 50 cm at a height of about 4 m to 10 m from the ground, an electric field fluctuation amount of about 3 dB or more is generated. Almost no. In addition, the number of fluctuations is none.

On the other hand, in the shielding side area 11, it is not recognized that there is a correlation between the electric field strength and the measurement height, and a severe amplitude change is shown. Moreover, the electric field fluctuation amount at the measurement point in the shielding side area 11 affected by the steel tower may exceed 10 dB at the maximum. The frequency of occurrence is overwhelmingly higher than the measurement points in the front area 10 and the number of fluctuations tends to increase.
From this result, in the front side area 10, only the direct waves 8, 8... Are received in the digital radio wave 7, but in the shielding side area 11, the scattered wave 9 is also added to the direct wave 8. Since the radio wave is received as the digital radio wave 7, it can be said that a severe amplitude change is caused by the influence of the scattered wave 9.

  In addition, Table 1 shows the relationship between the front side area 10 and the shielding side area 11 of the power transmission tower 2 and the channel group with respect to the received electric field fluctuation amount at the height of the antenna 5. Even in this case, the shielding-side area 11 has a larger electric field fluctuation amount than the front-side area 10. Further, since the electric field fluctuation amount irregularly changes as the height of the antenna 5 changes, it is not recognized that there is a correlation between the height of the antenna 5 and the electric field fluctuation amount.

  Further, the measured channel group includes those in which the received electric field fluctuation amount is 3 dB or more and the fluctuation frequency is two or more in the shielding side area 11. Moreover, the thing provided with either one is also included. On the other hand, in the front side area 10, there is no measured channel group in which the received electric field fluctuation amount fluctuates by 3 dB or more, and there is no fluctuation number of two or more.

  As a result, in the shielding-side area 11 of the power transmission tower 2, when electric field fluctuation characteristics that cannot occur due to the influence of the digital radio wave 7 reflected on the ground or the influence of a normal sneak wave are observed, It can be determined that there is a high possibility that reception is impossible because the electric field fluctuates due to the influence of the steel tower 2.

As described above, the determination method of the present embodiment includes a step of measuring the received electric field at each measurement height by changing the measurement height every 50 cm between 4 m and 10 m above the ground in the shielding side area 11, and adjacent Determining that the transmission tower 2 has an influence on digital terrestrial broadcasting when a channel in which the amount of fluctuation of the received electric field between the measurement heights is 3 dB or more and the number of occurrences is 2 or more is measured; , To have.
As a result, whether the cause of the inability to receive the digital radio wave 7 is due to the generation of the sneak wave or the generation of the scattered wave 9, the cause is identified, and the causal relationship between the transmission tower 2 and the reception failure is clarified. It becomes possible. Since the cause is resolved logically at an early stage, effective countermeasures can be taken without taking unnecessary measures against the reception failure. In addition, a logical explanation can be given to the parties or third parties of the radio disturbance, and troubles due to radio disturbance in the area can be reduced.

Further, the step of measuring the reception electric field at each measurement height by changing the measurement height every 50 cm between 4 m and 10 m above the ground in the shielding side area 11 and the reception electric field between the adjacent measurement heights. When a channel whose fluctuation amount is 3 dB or more and the number of occurrences is 2 times or more is measured, the step of determining that the transmission tower 2 has an influence on the digital terrestrial broadcasting, and the digital radio wave 7 in the shielding side area 11 A step of confirming a sneak wave generated when the digital radio wave 7 is incident on an obstacle, and a step of judging that the influence of the power transmission tower 2 is occurring when the sneak wave is not measured. Is to have.
As a result, whether the cause of the inability to receive the digital radio wave 7 is due to the generation of a sneak wave or the generation of the scattered wave 9, the cause is identified, and the causal relationship between the transmission tower 2 and the reception failure is clarified. It becomes possible. Since the cause is resolved logically at an early stage, an effective countermeasure can be taken without taking a wasteful countermeasure against the reception failure. In addition, a logical explanation can be given to a party or a third party having a radio disturbance, and troubles due to radio disturbance in the area can be reduced.

  Note that the determination method of the present invention is not limited to the above-described embodiment, and the configuration at the measurement point can be appropriately changed as necessary without departing from the spirit of the present invention.

  For example, the height of the antenna from the ground, the measurement interval, the comparison value of the electric field fluctuation amount, the occurrence frequency, etc. may be changed, and if the electric field fluctuation amount is compared, the design can be changed as appropriate. is there. In particular, since the height of the antenna from the ground is affected by the location conditions of ordinary houses, it is not necessarily limited to a height of 10 m from the ground, and may be higher than that and may be changed as appropriate. can do. Similarly, since the measured heights of the antennas are also affected by the general housing location conditions, they are not necessarily limited to the measured heights of every 50 cm, and can be changed as appropriate.

  In addition, the measurement of the electric field fluctuation amount does not necessarily need to use an antenna, and may be appropriately changed as long as the electric field fluctuation amount is measured.

  In urban areas, electric field fluctuation characteristics similar to those of power transmission towers may be generated by reflected waves from buildings such as buildings, in addition to the effects other than those of power transmission towers. However, in this case, since the scattered wave generated from the transmission tower reaches the antenna with almost no delay time, the electric field fluctuation characteristics due to the influence of the scattered wave from the transmission tower are measured by the method of measuring the delay time of the jamming radio wave. It can be determined whether or not.

  In addition, when a scattered wave delayed from the direct wave is received, the digital radio wave waveform has a ripple (periodic period) corresponding to the delay time, which is the time from when the direct wave is measured until the scattered wave is measured. Therefore, by observing the waveform, it is possible to determine whether or not the electric field fluctuation characteristic is due to the influence of the scattered wave from the power transmission tower when the radio wave interference occurs.

  Further, as a method for confirming a sneak wave, a method for measuring a delay time is generally known, but is not necessarily limited to this, and may be appropriately changed as long as it can be confirmed by another method.

It is explanatory drawing which shows the reception condition of a digital radio wave. It is explanatory drawing which shows the measuring method of a digital radio wave. It is explanatory drawing which shows the relationship between electric field strength and measurement height.

Explanation of symbols

  1 .... Transmitting antenna, 2 .... Transmission tower, 3 .... Measuring instrument, 4 .... Measuring instrument, 5 .... Antenna, 6 .... General housing, 7 .... Digital radio wave, 8 .... Direct wave, 9 .... Scattered waves, 10 .... front area, 11 .... shielded area.

Claims (4)

A method of determining the effect of a transmission tower on terrestrial digital broadcasting,
Measuring the received electric field at each measurement height by changing the measurement height by a predetermined amount in a vertical direction from a predetermined measurement point;
Determining that the power transmission tower is likely to have an influence on digital terrestrial broadcasting when the amount of fluctuation of the received electric field between adjacent measurement heights exceeds a predetermined number of times. ,
A method for determining the influence of a power transmission tower on terrestrial digital broadcasting, characterized by comprising: A method for determining the effect of a transmission tower on terrestrial digital broadcasting,
Measuring the received electric field at each measurement height by changing the measurement height by a predetermined amount in a vertical direction from a predetermined measurement point;
When the amount of fluctuation of the received electric field between adjacent measurement heights exceeds a predetermined number, a digital radio wave is measured at the predetermined measurement point and the digital radio wave is incident on an obstacle when a predetermined number of times occurs. A step of confirming the sneak wave generated by
If the sneak wave is not measured, determining that an influence by the transmission tower has occurred,
A method for determining the influence of a transmission tower on terrestrial digital broadcasting, characterized by comprising:   3. The determination of the effect of the transmission tower on terrestrial digital broadcasting according to claim 1 or 2, wherein in the step of measuring the received electric field, the measurement height is changed every 50 cm between 4 m and 10 m above the ground. Method. In the step of measuring the received electric field, it is determined that the power transmission tower has an influence on digital terrestrial broadcasting when a channel in which the amount of fluctuation of the received electric field is 3 dB or more and the number of occurrences is 2 or more is measured. The determination method of the influence which the power transmission tower of Claim 3 has on terrestrial digital broadcasting characterized by the above-mentioned.

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