HJ 972-2018Monitoring method for electromagnetic radiation environment of mobile communication base station (English PDF)

3.1 Mobile communication mobile communication

The two parties to the communication or at least one of them exchange information during the exercise. Such as moving bodies (people, vehicles, ships, airplanes) and fixed Communication between points or between mobile bodies.

3.2 Base station base station

A terrestrial station in the land mobile service, a wireless transceiver device serving a cell or a plurality of cells at the same site. Base station passed the line interface provides a wireless channel to and from the terminal.

3.3 Electromagnetic radiation environment sensitive target electromagnetic radiation environment-sensitive target Electromagnetic radiation environment monitoring needs to focus on the object. Including residential, school, hospital, office building and factory, etc.

Or study buildings.

4.1 Environmental conditions

The environmental conditions at the time of monitoring should be in accordance with the requirements of the instrument.

4.2 Monitoring instruments

4.2.1 Basic requirements

The working performance of the monitoring instrument should meet the requirements of the electromagnetic field to be tested, and it can cover the transmitting frequency, range, and Resolution, etc. can meet the monitoring requirements.

According to the purpose of monitoring, the monitoring instruments can be divided into non-selective broadband electromagnetic radiation monitors and frequency selective electromagnetic radiation monitors. Moving on when monitoring the electromagnetic radiation environment of a mobile communication base station, a non-frequency selective broadband electromagnetic radiation monitor is used; in the need to understand a plurality of electromagnetic radiation sources, each when the electromagnetic radiation contribution of the radiation source is used, the frequency selective electromagnetic radiation monitor is used.

Monitoring instruments with isotropic response probes (antennas) should be used for monitoring.

The monitoring results of the monitoring instrument should be selected from the rms value reading of the instrument. For the rms value, see GB/T 2900.1.

4.2.2 Non-frequency selective broadband electromagnetic radiation monitor

It refers to the electromagnetic radiation monitor with the isotropic response value of the comprehensive value of the field strength at all frequency points in the instrument frequency range.

In the case of environmental monitoring using a non-selected broadband electromagnetic radiation monitor, in order to ensure the quality of environmental monitoring, such instruments should comply with HJ/T 10.2, the basic requirements for its electrical performance are shown in Table 1.

Table 1 Basic requirements for electrical performance of non-frequency selective broadband electromagnetic radiation monitor

Project indicator

Frequency response

800MHz~3GHz ±1.5 dB

3GHz ±3 dB

Dynamic Range

The lower detection limit of the probe is <=1.1×10-4W/m2 (0.2 V/m) and the upper detection limit is >=25 W/m2 (100 V/m) Isotropic response to the entire monitoring system to assess its isotropy, isotropic <= 1 dB

4.2.3 Frequency selective electromagnetic radiation monitor

Refers to an electromagnetic radiation monitor capable of receiving and processing portions of the spectral components within the instrument's frequency range.

According to the specific monitoring needs, frequency selective electromagnetic radiation monitors with different ranges and different frequency ranges can be selected. These instruments should meet the requirements.

HJ/T 10.2, the basic requirements for its electrical performance are shown in Table 2.

Table 2 Basic requirements for electrical performance of frequency selective electromagnetic radiation monitor

Project indicator

5.1 Basic requirements

Before conducting monitoring work, collect basic information of the mobile communication base station under test, including. base station name, operating unit, construction site, Longitude and latitude coordinates, network system type, transmission frequency range, antenna ground height, antenna bracket type, number of antennas, and operating status.

Other information may be collected depending on the nature and purpose of the monitoring, including. transmitter model, nominal power, actual transmit power, antenna Parameters such as gain, antenna directivity type, and antenna direction angle.

When monitoring with a non-selected broadband electromagnetic radiation monitor, if the monitoring result exceeds the evaluation criteria for individual items specified in HJ/T 10.3, the selected frequency should be selected and frequency-selected using a frequency selective electromagnetic radiation monitor to determine the work of the point in the range of the transmitting frequency range of the mobile communication base station.

Rate density (or electric field strength) value.

5.2 Monitoring factors

The monitoring factor of the electromagnetic radiation environment of the mobile communication base station is a radio frequency electromagnetic field, and the monitoring parameter is power density (or electric field strength).

5.3 Monitoring points

The monitoring point is arranged in the cylindrical space with the ground projection point of the transmitting antenna of the mobile communication base station as the center and the radius of 50m as the bottom surface.

Representative electromagnetic radiation is sensitive to environmental targets.

When monitoring outside the building, the priority is placed in the public's daily life or working distance near the antenna, but it is not suitable to be deployed.

A location (such as a ladder) or a special way (such as climbing). When the mobile communication base station transmitting antenna is a directional antenna, the point priority the layout is within the direction of the main lobe of the antenna.

When monitoring in a building, the point is preferentially placed at the window (balcony) facing the antenna, and the probe (antenna) should be in the window frame (balcony) Within the interface, you can also select the center of the room. The distance between the probe (antenna) and equipment such as household appliances is not less than 1 m.

5.4 Monitoring height

The measuring instrument probe (antenna) is 1.7 m from the ground (or foot plane). It can also be monitored at other heights as needed and in the monitoring report Indicated in the middle.

5.5 Monitoring readings

During monitoring, the distance between the probe (antenna) and the operator's torso is not less than 0.5m, and avoid or minimize the occurrence of peripheral sporadic the interference of his electromagnetic radiation source.

Each measuring point is measured at least 5 times in succession, each monitoring time is not less than 15 seconds, and the maximum value in the steady state is read. If monitoring readings when the undulation is large, the monitoring time is appropriately extended.

When the monitoring instrument is an automatic measurement system, it should be set to the rms value detection method, each measurement time is not less than 6 minutes, data acquisition the set sampling rate is not less than 1 time/second.

5.6 Record

5.6.1 Recording of mobile communication base station information

Record the basic information and other information collected in Section 5.1.

5.6.2 Record of monitoring conditions

Record ambient temperature, relative humidity, and weather conditions.

Record the date of monitoring, the start and end time of monitoring, the type of monitor, the model and number of the monitoring instrument, and the model and number of the probe (antenna).

5.6.3 Record of monitoring results

Record the on-site monitoring point map, marking the location of the mobile communication base station antenna, monitoring points and other known electromagnetic radiation sources.

Record the name of the monitoring point, the vertical distance and horizontal distance of the monitoring point and the transmitting antenna of the mobile communication base station, and the monitoring data.

The spectrum profile is saved during frequency selective monitoring.

See Appendix A for the on-site monitoring records and the contents and format of the monitoring report.

5.7 Data Processing

5.7.1 Unit conversion

If the unit of the measured electric field strength read by the monitoring instrument is dB (µV/m), it can be converted into V/m according to formula (1).

Electric field strength value.

Where. x -- the reading of the monitoring instrument, dB (µV/m);

E -- electric field strength, V/m.

The electric field strength and power density can be converted according to formula (2) in the far field.

ES = (2)

Where. S -- power density, W/m2;

E -- electric field strength, V/m;

0Z -- free space intrinsic impedance, ohm = , 1200 piZ .

5.7.2 Data Processing

When monitoring with a non-frequency selective broadband electromagnetic radiation monitor, the measurement data is processed according to formula (3).

iXn

Where. X -- the average value of the measured point power density or electric field strength measurement, W/m2 or V/m;

iX - the i-th power density or electric field strength measurement, W/m2 or V/m;

n--Number of measurements.

When monitoring with a frequency selective broadband electromagnetic radiation monitor, the measurement data is in accordance with equations (4), (5) and (6).

Reason.

Iji Xn

Is SS

Is EE

Where. ijX -- the jth power density or electric field strength measurement of the frequency i point in a frequency band of the monitoring point, W/m 2 or V/m;

iX -- the average value of the measured power density or electric field strength of the frequency i point in a frequency band of the monitoring point, W/m2 or V/m;

n--Monitor the power density or electric field strength measurement times of the frequency i point in a certain frequency band;

sS -- monitors the power density value of a certain frequency band, W/m2;

iS--the power density measurement value of the frequency i point in a certain frequency band of the monitoring point, W/m2;

M--the number of measured frequency points in a certain frequency band of the monitoring point;

sE -- the electric field strength value of a certain frequency band of the monitoring point, V/m;

iE -- The measured value of the electric field strength at the frequency i point in a frequency band of the monitoring point, V/m.

For continuous monitoring, the measured data is processed according to formula (7).

sG Ek

Where. GE - the average value of the electric field strength of a certain frequency band measured within 24h (or within a certain period of time), V/m;

The number of measurements in a frequency band is measured within k--24 hours (or within a certain period of time).

According to the need, the maximum value maxE and minimum value minE in each monitoring can be separately counted, and the time is not exceeded in 50%, 80% and 95%.

Electric field strength values, 50%, E, , 80%, E and, Y, E.

The electromagnetic field distribution map can be drawn as needed, such as time and electric field strength, distance and electric field strength, frequency and electric field strength.