Circular No. 38/2020/TT-BTTTT Issuing "National Technical Regulations on Low-Power Wide Area Network (LPWAN) Radio Equipment in the 920 MHz to 923 MHz Band"

CIRCULAR

Issuing the "National Technical Regulation on Low Power Wide Area Network (LPWAN) Radio Equipment Operating in the 920 MHz to 923 MHz Band"

Pursuant to the Law on Standards and Technical Regulations dated June 29, 2006;

Pursuant to the Law on Telecommunications dated November 23, 2009;

WHEREAS, Decree No. 127/2007/NĐ-CP dated August 1, 2007 of the Government detailing and guiding the implementation of certain provisions of the Law on Technical Standards and Regulations;

Pursuant to Decree No. 78/2018/ND-CP dated May 16, 2018 of the Government amending and supplementing certain articles of Decree No. 127/2007/ND-CP dated August 1, 2007 of the Government detailing the implementation of certain provisions of the Law on Standards and Technical Regulations;

Pursuant to Decree No. 17/2017/NĐ-CP dated February 17, 2017, issued by the Government, on the functions, tasks, powers, and organizational structure of the Ministry of Information and Communications;

Pursuant to the proposal of the Director of the Science and Technology Department,

The Minister of Information and Communications issues this Circular stipulating the National Technical Regulation on Low Power Wide Area Network (LPWAN) Radio Equipment Operating in the 920 MHz to 923 MHz Band.

Article 1. Attached herewith is the National Technical Regulation on Low Power Wide Area Network (LPWAN) Radio Equipment Operating in the 920 MHz to 923 MHz Band (QCVN 122:2020/BTTTT).

Article 2. This Circular takes effect from July 1, 2021.

Article 3. Director of the Office, Heads of Science and Technology Departments, Heads of agencies and units under the Ministry of Information and Communications, Directors of Provincial Departments

of Information and Communications and organizations and individuals concerned shall be responsible for implementing this Circular./.

SOCIALIST REPUBLIC OF VIET NAM

Independence - Freedom - Happiness

-----------------------------

QCVN 122:2020/BTTTT

NATIONAL TECHNICAL REGULATION ON RADIO EQUIPMENT IN LOW POWER WIDE AREA NETWORKS (LPWAN) OPERATING IN THE 920 MHz TO 923 MHz FREQUENCY BAND

National technical regulation on radio equipment in the Low Power Wide Area Networks (LPWAN) operating in the 920 MHz to 923 MHz frequency band

HANOI - 2020

Table of Contents

Foreword

QCVN 122:2020/BTTTT was drafted by the Frequency Management Agency, reviewed by the Science and Technology Department, examined by the Ministry of Science and Technology, and issued together with Circular No. 38/2020/TT-BTTTT dated November 16, 2020.

AMENDMENT 1:2025 QCVN 07:2023/BXD

ON RADIO EQUIPMENT IN LOW POWER WIDE AREA NETWORKS (LPWAN)
IN THE 920 MHz TO 923 MHz FREQUENCY BAND

National technical regulation

on radio equipment in Low Power Wide Area Networks (LPWAN) operating in the 920 MHz to 923 MHz frequency band

Chapter 1. GENERAL PROVISIONS

1.1. Scope of Application

This regulation sets out technical requirements concerning frequency bands, technical conditions, and measurement methods for radio equipment in low power wide area networks (LPWAN) operating in the 920 MHz to 923 MHz band.

Radio equipment in LPWAN includes sensors (End-points) and access stations (Gateways) connected through a wireless interface; using shared frequency bands (920 MHz to 923 MHz) with other short-range radio equipment.

Radio equipment in LPWAN that uses frequencies allocated for public mobile communication services (IMT) is not within the scope of this regulation.

This regulation applies to products and goods that are radio equipment in low power wide area networks (LPWAN) with HS codes specified in Appendix D.

1.2. Applicability

This regulation applies to organizations and individuals, both domestic and foreign, engaged in production and business activities involving equipment within the scope of this regulation on the territory of Vietnam.

1.3. Referenced Documents

Recommendation ITU-T O.153 (10/92): "Basic parameters for the measurement of error performance at bit rates below the primary rate".

ETSI TS 103 060 (V1.1.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM); Short Range Devices (SRD); Method for a harmonized definition of Duty Cycle Template (DCT) transmission as a passive mitigation technique used by short range devices and related conformance test methods".

CISPR 16 (2006) (parts 1-1, 1-4 and 1-5): "Specification for radio disturbance and immunity measuring apparatus and methods; Part 1: Radio disturbance and immunity measuring apparatus".

Directive 2014/53/EU of the European Parliament and of the Council of 16 April 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of radio equipment and repealing Directive 1999/5/EC.

ETSI TR 100 028 (all parts) (V1.4.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM); Uncertainties in the measurement of mobile radio equipment characteristics".

ETSI TR 102 273-2 (V1.2.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM); Improvement on Radiated Methods of Measurement (using test site) and evaluation of the corresponding measurement uncertainties; Part 2: Anechoic chamber".

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ETSI TR 102 273-3 (V1.2.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM); Improvement on Radiated Methods of Measurement (using test site) and evaluation of the corresponding measurement uncertainties; Part 3: Anechoic chamber with a ground plane".

ETSI TR 102 273-4 (V1.2.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM); Improvement on Radiated Methods of Measurement (using test site) and evaluation of the corresponding measurement uncertainties; Part 4: Open area test site".

ETSI EN 300 220-1 (V3.1.1) (02-2017): "Short Range Devices (SRD) operating in the frequency range 25 MHz to 1 000 MHz; Part 1: Technical characteristics and methods of measurement".

1.4. Terms and Definitions

1.4.1. Acknowledgment

Brief information from the receiver to the message originator confirming successful receipt of the message.

1.4.2. Adjacent Channel

A frequency band, having a width equal to the nominal channel width (OCW), located on either side of the nominal channel.

Channel bandwidth --- Channel bandwidth --- Channel bandwidth --- Channel bandwidth --- Channel bandwidth

Figure 1 - Definition of adjacent channels

1.4.3. Ancillary Equipment

Equipment used in connection with a receiver or transmitter.

NOTE: Equipment is considered ancillary when:

Equipment used in conjunction with a receiver or transmitter to create additional operational and/or control features for a radio communication device (for example, to extend control to other positions or areas); and

Equipment that cannot be used independently to create independent usage functions of a receiver or transmitter; and

The receiver/transmitter it connects to has the ability to perform certain operations such as transmitting and/or receiving without auxiliary equipment (that is, it is not a sub-unit essential to maintain the basic function of the main device).

1.4.4. Channel Adaptivity

The capability to adapt to device modes without changing the transmission channel.

14.5. Channel Spacing

The distance, measured in Hz, between adjacent center frequencies.

1.4.6. Center Frequency

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The nominal center frequency of a frequency channel.

1.4.7. Conducted Measurement

A measurement performed by connecting directly to the device under test using a 50 Ω impedance termination.

1.4.8. Continuous Transmission

Transmission that is uninterrupted during the specified time period.

1.4.9. Cumulative On Time (Ton-cum)

The total of T_{nn} during the observation time Tobs.

NOTE: See Figure 2.

In this example Ton-cum = Ton,1 + Ton,2 *

Figure 2 - Illustration of cumulative on time

1.4.10. Dead Time

The time between the end of the last evaluation period of the clear channel assessment (CCA) and the start of transmission.

1.4.11. Dedicated Antenna

An antenna that can be detached, tested, and supplied with the radio equipment, designed as an integral part of the equipment.

1.4.12. Deferral Time

The random time a transmission is delayed before re-evaluating the clear channel assessment when a channel is occupied.

1.4.13. Disregard Time

The period announced by the manufacturer during which two separate radio emissions in a channel are considered a continuous emission.

NOTE: See Figure 4.

1.4.14. Duty Cycle

The ratio expressed as a percentage, of the cumulative transmission time T_on-cum during the observation time T_obs. DC = (T_on-cum/T_obs)_Fobs over an observation bandwidth F_obs.

1.4.16. Integral Antenna

A fixed antenna attached to the equipment and designed as an integral part of the equipment.

1.4.17. Listen Before Transmit

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A mechanism where a device applies a clear channel assessment before initiating transmission (also known as listen before talk).

1.4.18. Maximum Transmission Duration (T_on-Max) (maximum transmission duration T_on- Max)

The longest allowed transmission time T.

1.4.19. Message Initiator (MI)

A device that transmits a message to another device, such as a message responder.

1.4.20. Message Responder (MR)

A device that receives a message from another device, such as a message initiator.

1.4.21. Minimum Inter-Transmission Interval (T

off-Min

) (minimum inter-transmission interval T

off-

Min)

The shortest interval in a channel between two transmissions by the same device.

1.4.22. Observation Bandwidth (F

obs

)

The bandwidth within which the energy of a device is considered for the purpose of transmission time evaluation.

1.4.23. Observation Period (T

obs

)

Reference time period.

1.4.24. Occupied Bandwidth (OBW)

The width of a frequency band within which, below the lowest frequency and above the highest frequency, the average power radiated at each edge is only 0.5% of the total radiated power.

NOTE: See Figure 3.

1.4.25. Off Time (T

off

)

The time between two successful transmissions in a defined channel.

1.4.26. On Time (T

on

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)

The time successfully performing a transmission.

NOTE: See Figure 4

1.4.27. Operating Channel (OC)

The frequency band on which the device transmits, defined by two frequency edge values: Flow and Fhigh published by the manufacturer.

1.4.28. Operating Channel Bandwidth (OCW)

The width between two frequency values Flow and Fhigh published similarly to a defined channel.

1.4.29. Operating Frequency

The nominal center frequency of a frequency channel.

1.4.30. Operating Frequency Band

The frequency band in which the device operates and performs all designed functions, defined by two frequency edge values: Flow-OFB and Fhigh-OFB.

1.4.31. Out-of-Band Domain

The frequency band immediately outside the defined channel resulting from modulation processes but excluding spurious emissions.

Figure 3 - Occupied Bandwidth

1.4.32. Out-of-Band Emission

Emissions in the out-of-band domain.

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1.4.34. Radiated Measurements

Measurements related to the radiation field.

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Chapter 2. TECHNICAL PROVISIONS

2.1. General Requirements

1.4.35. Signal Threshold (P

ngưỡng

)

When requesting testing, the party with the equipment to be tested must provide along with the equipment all necessary information about the signal source for testing and device setup information.

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2.1.3. Classification of Receivers

The performance of receivers relates to their ability to operate normally when signals from other radio systems appear in adjacent bands. Receivers are classified based on their performance as shown in Table 1a.

The selection of receiver types must pay particular attention to the risk of interference from other systems operating in the same band or adjacent bands, especially applications related to safety and security. Manufacturers must inform users about the risks that may cause the equipment to not function properly according to its intended use.

Table 1a - Receiver Classification

The type of receiver must be recorded in the test results and user manual of the equipment.

2.2. Testing Conditions, Signal Sources, and Environmental Temperature

2.2.1. Test Signals

2.2.1.1. Test Signals for Data

For specific testing, the test signal is a modulated or unmodulated carrier wave generated by the EUT. The EUT has the capability to generate the following test signals:

D-M1: A test signal consisting of an unmodulated carrier wave. This signal is optional but helps simplify some tests.

D-M2: A test signal is a modulated carrier wave in normal operation mode with the largest occupied RF bandwidth. The preferred test signal includes a minimum 511-bit long pseudo-random sequence according to Recommendation ITU-T O.153. This sequence will be repeated continuously.

D-M2a: A test signal described in D-M2 but generated intermittently. Each RF signal generated must be identical except for the data sequence, which occurs frequently over time, can be precisely repeated, and the duration reflects normal operation of the EUT except for compliance with duty cycle limits.

D-M3: A test signal describes normal operation of the EUT. This signal must be agreed upon by the test laboratory and manufacturer in cases where selected messages are transmitted or decoded within the device. This test signal may be formatted and may contain error detection and correction codes.

The test signal can be generated by applying the original signal measurement to the modulation port on the device or generated internally within the device. Details of the method shall be reported by the manufacturer and recorded in the test report.

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For each test, the test signal will be recorded in the test report. Recommended test signals for each test are specified in Table 1.

Table 1 - Test Signals

2.2.2. Test Power Supply

2.2.2.1. General Requirements

The equipment under test is powered using a suitable test power supply as specified in 2.2.2.2 or 2.2.2.3 depending on whether the equipment is externally powered or internally integrated. If externally powered, the external power supply is tested according to 2.2.2.2, then the internal power supply is used according to 2.2.2.3.

The test power supply used must be recorded in the test report.

2.2.2.2. External Test Power Supply

The external test power supply must be capable of generating normal and high test voltages as specified in 2.2.3.2 and 2.2.4.2. The internal impedance of the external test power supply must be low enough not to affect the test results. Depending on the purpose of the test, the voltage of the test power supply must be measured at the input of the device. Note, this may be the main connection point of the device to an external power supply. The external test power supply must be isolated appropriately and applied as close to the battery terminals of the device as possible. For radiation measurements, any external power supply leads must be arranged so as not to affect the measurement (e.g., using ferrite on the cable).

During testing, the voltage of the external test power supply will remain within a tolerance range of < ±1% relative to the initial voltage of each test. This tolerance value may have a certain impact on some measurements. Therefore, for these measurements, a smaller tolerance value should be used to increase the accuracy of the measurement.

For radiation emission testing, any external power supply leads must be arranged so as not to affect the measurement.

2.2.2.3. Integrated Test Power Supply

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For radiation emission testing on mobile devices with built-in antennas or detachable antennas, a fully charged internal power supply is used. Batteries are used as provided or recommended by the manufacturer. If batteries are used, at the end of the test, the voltage must be within a tolerance of < ±5% compared to the initial voltage at the start of the test. In case of non-compliance, apply C.3.1.

If necessary, for conduction measurements, harsh testing conditions, or using a test fixture, an external power supply as described in 2.2.2.2 with required voltage can replace the battery as provided or recommended. This must be recorded in the test report.

2.2.3. Normal Testing Conditions

2.2.3.1. Normal Temperature and Humidity

The normal temperature and humidity conditions for testing must fall within the following ranges:

Temperature: +15°C to +35°C.

Relative Humidity: 20% to 75%.

If testing is not conducted under the above conditions, the temperature and humidity of the environment throughout the testing period must be recorded in the test report.

2.2.3.2. Normal Test Power Supply

a) Grid Voltage

The normal test voltage for equipment connected to grid voltage must be the nominal voltage. For this Standard, the nominal voltage will be the declared voltage or any voltage declared during the design of the equipment.

The frequency of the test power supply corresponding to alternating current must be within the range of 49 Hz to 51 Hz.

b) Common Lead-Acid Battery Sources

For wireless devices designed to operate with lead-acid batteries, the normal test voltage is 1.1 times the nominal battery voltage (e.g., 6 V, 12 V, ...).

c) Other Sources

For operation with other types of power sources or batteries (primary or secondary), the normal test voltage must be recognized by both the manufacturer and the test laboratory. These values are clearly stated in the test results.

2.2.4. Harsh Testing Conditions

2.2.4.1. General Requirements

Unless otherwise specified, testing conducted under harsh testing conditions shall simultaneously apply both temperature and voltage harsh conditions.

2.2.4.2. Harsh Temperature Conditions

a) General Requirements

Prior to conducting measurements, the equipment must reach thermal equilibrium in the test chamber. The equipment must be turned off during the thermal stabilization period.

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In cases where the equipment contains continuously operating thermal stabilization circuits, these circuits will be activated for 15 minutes after achieving thermal equilibrium, and the equipment must meet the prescribed requirements.

If thermal equilibrium is not verified through measurement, the minimum thermal stabilization time must be at least 1 hour or the duration determined by the testing laboratory. The sequence of measurements must be selected, and humidity within the test chamber must be controlled to prevent condensation.

b) Procedure for Equipment Designed for Continuous Operation

If the equipment is designed by the manufacturer for continuous operation, the testing procedure shall be carried out as follows:

Before high-temperature testing, the equipment must be placed in the test chamber until thermal equilibrium is achieved. Subsequently, the equipment will be activated under transmission conditions for approximately 30 minutes, and it must meet the prescribed requirements.

For low-temperature testing, the equipment must be placed in the test chamber until thermal equilibrium is achieved. Subsequently, the equipment will be activated for about 1 minute, and it must meet the prescribed requirements.

c) Procedure for Equipment Designed for Non-Continuous Operation

If the equipment is designed by the manufacturer for non-continuous operation, the testing procedure shall be carried out as follows:

Before high-temperature testing, the equipment must be placed in the test chamber until thermal equilibrium is achieved. The equipment will:

Switch on and off according to the operating cycle declared by the manufacturer over a period of 5 minutes or:

If the manufacturer declares a period exceeding 1 minute, transmit under conditions not exceeding 1 minute, then the equipment will be in an off or wait state for approximately 4 minutes, and it must meet the prescribed requirements.

For low-temperature testing, the equipment must be placed in the test chamber until thermal equilibrium is achieved. Subsequently, the equipment will switch to a wait or receive mode for approximately 1 minute, and it must meet the prescribed requirements.

d) Harsh Temperature Range

Testing under harsh temperature conditions must be performed according to the procedures specified in 2.2.4.2.a at the upper and lower temperatures as published by the manufacturer.

Example of commonly used ranges for equipment:

General: from -20 °C to +55 °C;

Handheld: from -10 °C to +55 °C;

Indoor use: from +5 °C to +35 °C;

Outdoor use: from -40 °C to +125 °C.

The testing report must specify the range used.

2.2.4.3. Harsh Source Voltage Testing

a) Grid Voltage

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For equipment connected to an alternating current power supply, the harsh testing voltage must be the rated voltage ±10%. For equipment operating outside the grid voltage range, 2.2.4.3.d applies.

b) Common Lead-Acid Battery Sources

When wireless equipment is designed to operate from a standard lead-acid battery, the harsh testing voltage will be 1.3 and 0.9 times the rated battery voltage (6 V, 12 V, etc.).

For applications using gel-cell batteries, the harsh voltage will be 1.15 and 0.85 times the nominal battery voltage declared.

c) Other Battery Sources

The low-voltage testing for equipment powered by other types of batteries is as follows:

For equipment with a battery indicator, the final voltage as indicated;

For equipment without a battery indicator, the final voltage will be used as follows:

+ For Leclanche or Lithium batteries: 0.85 times the rated battery voltage;

+ For Nickel-Cadmium batteries: 0.9 times the rated battery voltage.

For other types of batteries or equipment, the low-voltage testing for discharge conditions will follow the manufacturer's declaration.

The high-voltage testing will follow the manufacturer's declaration if there is a difference with

d) Other Sources

For equipment using other sources or capable of operating from multiple sources, the harsh testing voltage must be agreed upon by the equipment manufacturer and the testing laboratory. This is recorded in the testing report.

2.2.5. Testing Equipment with Compatible Power Levels

Equipment with output energy compatibility modules must be declared. Each module will be tested when combined with the equipment.

2.2.6. Dummy Antenna

In cases where a dummy antenna must be used to test the equipment, it must be a pure resistive load connected to the antenna connector. The Standing Wave Ratio (VSWR) at the 50 Ω RF connector end must not exceed 1.5:1 across the entire frequency band to be tested.

2.2.7. Equipment Without External RF Connectors

2.2.7.1. General Conditions

For equipment with integrated antennas or connectors other than 50 Ω coaxial connectors, the measurements are conducted as follows:

Internal connector installation;

Temporary connector installation;

Using a multi-connector box.

2.2.7.2. Equipment With Internal Connector

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The equipment under test (EUT) with a 50 Ω coaxial connector between the antenna and circuitry can be used to perform measurements. Access to the connector must be wired according to the schematic. The actual use of internal antennas for measurements must be recorded in the testing report.

2.2.7.3. Equipment With Temporary Antenna Connector

For equipment with a standard antenna that can be connected, it may be tested for emission measurements. The manufacturer must attend the testing session at the end of emission measurements to disconnect the antenna and install a temporary connector. Laboratory personnel will not connect or disconnect any temporary antenna connectors.

Additionally, two sets of equipment may be sent to the testing laboratory, one set with a temporary antenna connector disconnected from the antenna and another set connected to the antenna. Each set will be used for appropriate tests. There will be two identical sets of equipment except for the antenna connector.

2.2.7.4. Measurement Box

The measurement box is a structure for connecting integrated antennas with a 50 Ω RF terminal at all frequencies required for the measurements.

The measurement box shall only be used for relative measurements.

Information on the measurement box is referenced in Appendix B.

2.2.8. Conducted Measurements and Radiated Measurements

Although the method of measurement for conducted measurements is allowed, it should be noted that the equipment and its antenna accessories must comply with current technical requirements.

The measurement method using a conducted connection may be substituted for radiated measurements. For certain measurements, an equivalent test using a measurement box may be used as a substitute. In such cases, the appropriate procedure establishing reference levels will be used and recorded.

If the specified measurement method is radiated measurement, it cannot be substituted with conducted measurement or with a measurement box.

Detailed guidance on radiated measurement setup is described in Appendix C.

Guidance on measurements that can be performed using a conducted connection or a measurement box is provided in Table 2.

Table 2 - Measurement Options

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If the equipment under test has more than one antenna port, for example separate antennas for receiving and transmitting or separate antennas for different operating frequencies or various types of antennas, then:

If every antenna port has a 50 Ω connector, conducted measurements can be performed as in Table 2. All antenna ports are connected to 50 Ω as described in 2.2.6.

In other cases, only radiated measurements shall be performed. All antennas must be mounted in typical usage conditions.

NOTE: Replacing an antenna with a transmission line may affect the operation of another antenna.

2.2.9. Receiver

2.2.9.1. Concept

The term "Receiver" refers to a frequency-selective voltmeter or a spectrum analyzer. Detailed information is in A.1. Unless otherwise specified, an RMS demodulator will be used.

2.2.9.2. Reference Bandwidth

Typically, the resolution bandwidth (RBW) of the receiver must be equal to the reference bandwidth (RBW_ref) in Table 3.

To increase accuracy, sensitivity, and efficiency of the measurement, RBW may differ from RBW_ref. When RBW_Measurement < RBW_ref, the result:

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Where:

P(i) is the measurement sample with RBW_Measurement:

n is the number of samples within RBW_refi

B is the corresponding value at RBW_ref.

When RBW_Measurement > RBW_ref, the result for wideband emission is:

B = A + 10log(RBW_ref/RBW_Measurement)

Where:

A is the measured value at a measurement bandwidth greater than RBW_Measurement,

B is the corresponding value at RBW_ref.

2.3. Interpretation of Measurement Results

The interpretation of measurement results for the measurements described in this document is recorded in the test report as follows:

The measured values related to the corresponding limits will be used to determine whether the equipment meets the requirements of the document;

The uncertainty value of each parameter measurement must be included in the test report;

The recorded value of each non-guaranteed measurement must be equal to or lower than the value in Table 4.

For the measurement methods according to this document, error margins must be calculated and correspond to the expansion factors (coverage factors) k = 1.96 or k = 2 (at confidence levels of 95% and 95.45%, respectively, for normal distribution according to the Gaussian function). The calculation principle of errors according to ETSI TR 100 028, particularly in Appendix D of ETSI TR 100 028-2.

Table 4 - Measurement Uncertainty

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2.4. Requirements and Measurement Methods

2.4.1. Operating Frequency

2.4.1.1 Concept

The nominal operating frequency is the center frequency of the channel with the OCW bandwidth.

2.4.1.2 Limit

The operating frequency of the equipment must be within the range from 920 MHz to 923 MHz.

2.4.1.3 Measurement Method

The information in Table 5 must be recorded in the test report.

Table 5 - Information Recorded for Test Report for Operating Frequency Measurement

2.4.2. Unwanted Emission in Spurious Transmission

2.4.2.1 Concept

a) Unwanted emission for transmission mode

Figure 5 - Mask for unwanted emissions in spurious transmission domain with reference bandwidth

Spurious emissions are unwanted emissions in the spurious transmission domain at frequencies other than the active channel and outside the transmission band. The relationship of the spurious transmission domain is shown in Figure 5.

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b) Unwanted emission for other modes

Spurious emissions from the EUT are a combination at any frequency emitted by the device and antenna.

2.4.2.2 Reference Limits

The power of any unwanted emission in the spurious transmission domain must not exceed the value in Table 6.

Table 6 - Spurious Emission Limits

2.4.2.3 Measurement Method

a) Measurement Conditions for Transmission Mode

Set the EUT to operate normally in the corresponding mode.

For EUTs without external 50 Ω coaxial antenna connectors, the spurious emission level will be established according to the radiated measurement sequence at 2.4.2.3.c.2.

For all other EUTs, the spurious emission level is established:

According to the conducted measurement sequence at 2.4.2.3.c.1 and

According to the radiated measurement sequence at 2.4.2.3.c.2 with the antenna port terminated with a dummy load.

i) The transmitter is operated at the lowest and highest frequencies according to the manufacturer's declaration. Additional frequencies may be tested.

ii) The measurement is performed when the EUT operates at its maximum power level according to the manufacturer's declaration and when the EUT is in standby mode.

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NOTE 2: If the RBW used for the measurement differs from RBW_ref, the adjustment according to 2.2.9.2 shall be applied.

b) Measurement Conditions for Reception Mode and Other Modes

Set the EUT to operate normally in the corresponding mode.

For EUTs without external 50 Ω coaxial antenna connectors, the spurious emission level will be established according to the radiated measurement sequence at 2.4.2.3.c.2.

For all other EUTs, the spurious emission level is established.

According to the conducted measurement sequence at 2.4.2.3.c.1 and

According to the radiated measurement sequence at 2.4.2.3.c.2 with the antenna port terminated with a dummy load.

c) Measurement Sequence

C.1. Conducted Measurement

Connect the EUT's antenna port to a dummy load and connect the output of the dummy load to the receiver.

Operate the EUT.

Apply 2.4.2.3.a for the transmission mode.

Adjust the receiver to the frequency band according to Table 8.

Table 8 - Frequency Band for Measuring Spurious Emission Using the Lead Method

NOTE: Only measure within the 4 GHz to 6 GHz range if spurious emission is detected within the limit of 10 dB between 1.5 GHz and 4 GHz.

For each frequency component of the spurious emission determined, the power level will be measured and noted.

C.2. Measurement of Radiation

Select the appropriate measurement position from the description provided in C.2.

Connect the EUT to its normally operating antenna.

Connect the output of the test antenna to the receiver. Perform the measurement described using the appropriate radiation measurement method as described in C.6.1 (or C.6.2), depending on the measurement position, then proceed with C.6.3. Start the EUT.

Apply 2.4.2.3.a to the transmission mode.

Adjust the receiver to the frequency band according to Table 9.

Table 9 - Frequency Band for Measuring Spurious Emission Using the Radiation Method

For each frequency component of the spurious emission determined within the frequency band according to Table 9, the spurious emission power level is established using the process described in C.6 and recorded in the report.

NOTE: The highest signal level measured by the receiver is recorded both vertically and horizontally polarized.

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The radiation measurement in C.6.1 (or C.6.2) is performed by the substitute measurement defined in C.6.3 with the signal generator set to the frequency of the determined spurious emission component, if necessary, the input attenuation of the device is adjusted to increase the receiver's sensitivity.

The effective radiated power measurement of components with levels greater than two power levels at the input of the substitute antenna, the increase in antenna gain of the substitute antenna is adjusted by cable loss (dB value).

Record the measured power level in the test report for each spurious emission component.

2.4.3. Effective Radiated Power

2.4.3.1. Concept

Effective radiated power is the power radiated in the direction of maximum emission level under specified measurement conditions for an unmodulated signal. For devices with fixed or temporary antenna connections, effective radiated power can be taken as the power at the connection point considering the antenna gain.

2.4.3.2. Limit

Effective radiated power does not exceed 14 dBm ERP.

2.4.3.3. Measurement Method

a) Effective Radiated Power (Using the Lead Method)

a.1. General Requirements

The measurement is only conducted for EUT with a fixed external antenna connector.

a.2. Measurement Conditions

i) Conduct the measurement at the lowest and highest operational frequencies as declared by the manufacturer. Additional test frequencies may be added.

ii) Turn on the transmitter, if possible, unmodulated and adjust the receiver to the transmitter frequency. Do not use the D-M1 test signal (unmodulated carrier) for equipment with non-fixed envelope modulation.

iii) The RBW of the spectrum analyzer must be wide enough to cover the entire power envelope (≥ OCW) of the EUT signal.

a.3. Test Procedure

The transmitter is connected to the dummy load as per 2.2.6 and the conducted power is measured by the receiver as per 2.2.9.

In case of non-fixed envelope modulation, use the peak separation mode.

The maximum antenna gain will be used as reported by the manufacturer and recorded in the test report.

The effective radiated power limit (ERP) is calculated by adjusting the maximum conducted power (Pcond) by the antenna gain (compared to dipole level) (ERP = Pcond + antenna gain).

Information in Table 10 is recorded in the test report.

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Table 10 - Information Recorded in the Test Report for Effective Radiated Power Measurement Using the Lead Method

b) Effective Radiated Power (Radiation Measurement)

b.1. General Requirements

This method applies to EUT not measured as per 2.4.3.3.a.

b.2. Measurement Conditions

i) Conduct the measurement at the lowest and highest operational frequencies as declared by the manufacturer. Additional test frequencies may be added.

ii) Conduct the measurement at the highest expected operating power level of the transmitter.

iii) Turn on the transmitter, if possible, unmodulated and adjust the receiver to the transmitter frequency. Do not use the D-M1 test signal (unmodulated carrier) for equipment with non-fixed envelope modulation.

iv) The RBW of the spectrum analyzer must be wide enough to cover the entire power envelope (≥ OCW) of the EUT signal.

v) In case of detachable antennas, the antenna is installed as it would be used normally.

vi) For measurements under extreme temperature conditions, use internal or temporary connectors instead of couplers.

b.2. Measurement Procedure

An appropriate measurement position will be selected according to the description in C.2 and the radiation power will be set according to the procedure described in C.6.1 (or C.6.2) depending on the measurement position as per C.6.3.

Use the peak separation mode in case of non-fixed envelope modulation.

Record information in Table 11 in the test report.

Table 11 - Information Recorded in the Test Report for Effective Radiated Power, Equivalent Power, Plus Antenna Gain of the Equipment

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NOTE: In case of detachable antennas, the antenna gain as reported by the manufacturer.

2.4.4. Duty Cycle

2.4.4.1. Concept

Duty cycle is the percentage ratio of the transmission time Ton-cum to the observation time Tobs.

DC = (Ton-cum / Tobs) at the observed frequency Fobs

Unless otherwise specified, Tobs is 1 hour and the observation bandwidth Fobs is within the operating frequency band. Each transmission includes a radio signal or a series of radio signals within an intrinsic period < TDis.

A device may operate simultaneously on multiple bands, duty cycle limits for each individual band apply to each transmission within that band.

In case of multi-carrier modulation within a band, the duty cycle applies to the entire signal performing the transmission (e.g., OFDM).

The device may be activated manually within a predetermined time or by an external source. Depending on the activation method, the time may be predetermined or random.

2.4.4.2. Limit

The duty cycle of LPWAN equipment does not exceed 10% (applicable to access stations/gateways) and does not exceed 1% (applicable to sensor/end-point devices).

2.4.4.3. Measurement Method

The evaluation of a cycle is based on the observation time Tobs over the observation bandwidth Fobs. Unless otherwise specified, Tobs is 1 hour and the observation bandwidth is the operating band.

The representative period is the time during which the equipment operates in normal use mode. Normal use mode is defined as the response of the device to 99% of transmissions generated throughout the device's lifetime.

The setup, trial operation, and maintenance procedures are not included in the normal operating cycle.

When the confirmation mode is used, the supplementary transmitter must declare once the correct timing message from the responder unit, regardless of whether it is within the task cycle of the initiating message unit or the response task cycle.

NOTE: The purpose of the principle is to prevent the EUT from exceeding the maximum operating cycle value.

2.4.5. Occupied Bandwidth

2.4.5.1. Concept

Occupied bandwidth (OBW) is the frequency range where 99% of the total average emission power is concentrated. In the case of a symmetrical spectrum, the residual part of the total power (denoted as β) will be divided equally into β/2 on each side of the spectrum. Unless otherwise specified, β/2 is taken as 0.5% as described in Figure 3.

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The maximum occupied bandwidth includes adjacent bands above individual emission levels and frequency errors or offsets under severe measurement conditions.

2.4.5.2. Limits

The operating channel is declared and fully contained within the operating frequency range.

The maximum occupied bandwidth at 99% level will lie within the operating channel defined by the lower and upper frequencies.

2.4.5.3. Measurement Method

a) Measurement Conditions

i) Conduct the measurement at the lowest and highest operational frequencies as declared by the manufacturer. Additional test frequencies may be added.

ii) Perform measurements with a spectrum analyzer.

iii) For devices with effective emission power ≤ -30 dBm, OBW can be measured or obtained using OCW within the operating frequency range.

b) Radiation Measurement

An appropriate measurement position will be selected according to the description in C.2 and the measurements will be carried out according to 2.4.5.3.d using the corresponding radiation measurement methods described in C.6.

c) Conducted Measurement

A dummy antenna will be connected between the EUT and the measuring instrument through an appropriate attenuator.

Perform the measurements according to 2.4.5.3.d.

d) Measurement Procedure

The spectrum analyzer will be configured for the parameters listed in Table 12.

Table 12 - Measurement Parameters for Maximum Occupied Bandwidth Measurement

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The OBW measurement is performed under normal and severe measurement conditions. Any requirement for the largest OBW under severe conditions is determined by adding and subtracting the frequency error results above and below for each bandwidth measurement in this test.

Step 1:

To operate the EUT at the highest operating frequency as declared by the manufacturer with the appropriate test signal.

Adjust the signal attenuation to ensure that the signal power envelope is sufficiently higher than the noise floor of the spectrum analyzer to avoid including noise signals on both sides of the power envelope in the measurement.

Step 2:

Mark the spectrum analyzer at the highest value obtained.

Step 3:

Use the 99% occupied bandwidth function on the spectrum analyzer to measure the occupied bandwidth of the signal.

d) Record Information

For each measurement condition, the information in Table 13 will be recorded in the test report.

Table 13 - Recording Information in the Test Report for Occupied Bandwidth

2.4.6. Out-of-Band Emission from Transmitters

2.4.6.1. Concept

Define two out-of-band regions, one for OC (Figure 6) and one for the operating frequency band (Figure 7). The spectrum masks for the two out-of-band regions may overlap.

Figure 6 - Out-of-band emission region for the operating frequency channel with reference bandwidth

The out-of-band emission applies to the operating frequency channel as shown in Figure 6.

Figure 7 - Out-of-band emission region for the operating frequency band with reference bandwidth

The limits apply to the frequencies immediately above and below the operating frequency band as shown in Figure 7.

Note: Flow OFB is the lower edge of the operating frequency band;

high_ofb is the upper edge of the operating frequency band.

2.4.6.2. Limits

The emission level of the EUT in the out-of-band region for the operating channel and the operating frequency band will be less than or equal to the level of the spectrum mask at Table 14.

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Table 14 - Emission Limits in the Out-of-Band Region

2.4.6.3. Measurement Method

a) Measurement Conditions

i) Perform the test according to 2.4.6.3.b if the EUT does not have a fixed or temporary connection port.

ii) Perform the test according to 2.4.6.3.c if the EUT has a fixed or temporary antenna connection port.

iii) For measurements under severe temperature conditions, use an internal or temporary connection instead of a junction box.

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b) Radiation Measurement

Perform the measurement according to 2.4.6.3.d depending on the selected measurement position suitable for the corresponding radiation measurement method described in C.6.1 (or C.6.2) or C.6.3.

c) Conducted Measurement

Connect the EUT and the measuring instrument through a dummy antenna with an appropriate attenuator. Perform the measurement according to 2.4.6.3.d.

d) Measurement Procedure

Table 15 - Measurement Parameters for Out-of-Band Channel Operating Frequency Measurement

Configure the measuring instrument according to the parameters in Table 15.

Step 1:

Start the EUT at the highest operating frequency as declared by the manufacturer with the appropriate test signal.

Record the signal shape when stabilized below the out-of-band spectrum mask for the operating channel.

Step 2:

Reconfigure the measuring instrument with the corresponding parameters in Table 16.

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Restart the EUT with the appropriate test signal at the lowest operating frequency as declared by the manufacturer.

If the device uses only one operating frequency in the operating frequency band, perform the measurement with the designated operating frequency.

Record the signal shape when stabilized below the out-of-band spectrum mask for the operating channel and the operating frequency band spectrum mask.

Step 3:

Reconfigure the measuring instrument with the corresponding parameters in Table 17.

Table 17 - Parameter Settings for Out-of-Band Measurement (Upper Band Edge)

Restart the EUT with the appropriate test signal at the highest operating frequency as declared by the manufacturer.

If the device uses only one operating frequency in the operating frequency band, perform the measurement with the designated operating frequency.

Record the signal shape when stabilized below the out-of-band spectrum mask for the operating channel and the operating frequency band spectrum mask.

Step 4:

For devices that quickly respond to frequency changes, repeat the measurement for each operating frequency.

Step 5:

If required, repeat the measurement from step 1 to step 5 under severe measurement conditions.

2.4.7. Instantaneous Power

2.4.7.1. Concept

The instantaneous power of the transmitter is the power concentrated at frequencies outside the operating channel due to the switching on and off of the transmitter.

2.4.7.2. Limits

The instantaneous power shall not exceed the value listed in Table 18.

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Table 18 - Instantaneous Power Limit of the Transmitter

2.4.7.3. Measurement Method

a. Measurement Conditions

1) Perform measurements at the lowest and highest operating frequencies as declared by the manufacturer. Additional measurements at other frequencies may be performed.

2) Conduct measurements at the highest expected operating power level for the transmitter.

b. Measurement Procedure

Connect the output of the EU to a spectrum analyzer or equivalent measuring device.

Measurements are conducted in zero-span mode. Set the center frequency of the spectrum analyzer with a deviation from the operating center frequency. The values of the deviation and corresponding RBW settings are listed in Table 19.

Table 19 - RBW for Instantaneous Power Measurement

NOTE: Maximum (sample RBW 1, 3, 10 kHz) is the maximum bandwidth commonly equipped on spectrum analyzers.

Example: If the OCW is 25 kHz, then the RBW value corresponding to an OCW frequency deviation of 3 kHz is 3 kHz. Other setting parameters are listed in Table 20, and if the OCW is 250 kHz, the RBW corresponding to an OCW frequency deviation of 30 kHz is 30 kHz.

Table 20 - Parameters for Instantaneous Power Measurement

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Use the D-M3 modulation mode. Configure the spectrum analyzer according to Table 20 and perform a measurement for each frequency deviation. The EUT will transmit at least five D-M3 test signals. Record the peak value and repeat the measurement for each frequency deviation listed in Table 19.

Convert the recorded power value to the measured power value for RBW_ref using the formula in 2.2.9.2.

2.4.8. Transmitter Operation Under Low Voltage Conditions

2.4.8.1. Concept

Low voltage operation is the ability of the equipment to maintain the operating frequency and not generate emissions exceeding the relevant limits when the battery voltage drops below the harsh low voltage level.

This requirement applies only to EUT devices that use batteries.

2.4.8.2. Limits

The requirement for transmitter operation under low voltage conditions applies only to devices powered by batteries.

When the voltage drops below the operating voltage as declared by the manufacturer, the device must:

a) Maintain the active channel OC without exceeding any limit (e.g., duty cycle); or

b) Reduce the effective radiated power below the emission threshold without exceeding any limit (e.g., duty cycle); or

c) Shut down (stop function).

2.4.8.3. Measurement Method

a) Measurement Conditions

Conduct measurements at the operating frequency as declared by the manufacturer.

b) Measurement Procedure

Step 1:

Start the EUT operating at the declared operating frequency with an appropriate test signal and normal operating voltage.

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Measure and record the center frequency of the transmitted signal.

Step 2:

Gradually reduce the operating voltage in suitable steps until it reaches zero.

Measure and record the center frequency of the transmitted signal.

Record any abnormal signs.

2.4.9. Receiver Input Overload

2.4.9.1. Concept

Receiver input overload is the measurement of the receiver's ability to obtain a desired modulated signal with a reduction in level not exceeding a specified value in the presence of an unwanted signal at any frequency except for spurious responses or adjacent channel or band frequencies.

2.4.9.2. Reference Limits for Type 2 Receivers

The receiver input overload level for the specified frequency offset must be greater than or equal to the limit in Table 21, except at frequencies with spurious responses.

Table 21 - Input Overload Level Limits for Type 2 Receivers

2.4.9.3. Reference Limits for Type 1.5 Receivers

The receiver input overload level for the specified frequency offset must be greater than or equal to the limit in Table 22, except at frequencies with spurious responses.

Table 22 - Input Overload Level Limits for Type 1.5 Receivers

2.4.9.4. Reference Limits for Type 1 Receivers

The receiver input overload level for the specified frequency offset must be greater than or equal to the limit in Table 23, except at frequencies with spurious responses.

Table 23 - Input Overload Level Limits for Type 1 Receivers

Additionally, increase the signal generator A level by +40 dB from step 1 to step 4 as per 2.4.9.5.d.

2.4.9.5. Measurement Method

a) Measurement Conditions

i) Perform the measurement with the center frequency as declared by the manufacturer

ii) Follow 2.4.4.9.5.b if the device under test does not have a fixed or temporary antenna connector.

iii) Follow 2.4.9.5.c if the device under test has a fixed or temporary antenna connector.

b) Radiation Measurement

The measurement position is carried out according to C.2.

Signal generators A and B are connected together as shown in Figure 8 and must be placed outside the measurement position.

The output of the combiner will be connected to the test antenna with the same polarization as the antenna of the device under test. The test antenna must be located within the measurement area.

Place the device under test on the rotating table in the direction of maximum sensitivity.

Follow the procedure as described in 2.4.9.5.d.

c) Direct Measurement

Two signal generators A and B are connected to the test setup as shown in Figure 8,

Perform the measurement as per 2.4.9.5.d.

Figure 8 - Receiver Input Overload Measurement Setup

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d) Measurement Procedure

Signal generator A transmits an appropriately modulated test signal at the receiver EUT operating frequency.

Signal generator B transmits an unmodulated signal.

Measurements are performed at the frequencies of unwanted signals at the defined frequency offsets to avoid spurious responses. Additional measurement points required by technical specifications should be included.

If the receiver has several operating frequency bands, measure the receiver input overload at least once in each band.

Step 1:

Turn off signal generator B. Adjust the signal generator A to emit a signal at the lowest level that yields the desired response or exceeds the following reference level:

S = 10logRB kHz - 4 dBμV emf

Or

$S{p}=10logRB{kHz}-117dBm$

Where: S_p is the sensitivity expressed in dBm;

RB is the receiver bandwidth declared in kHz.

The receiver bandwidth RB is declared by the manufacturer. RB is the 3 dB bandwidth selectivity of the receiver.

For example, the receiver sensitivity for a device with a channel spacing of 25 kHz and a bandwidth of 16 kHz does not exceed +8 dBμV emf for a receiver with a 50 Ω input impedance. This corresponds to a receiver sensitivity of -105 dBm.

Then increase the output level of signal generator A by 3 dB unless otherwise specified by technical requirements.

Step 2:

Turn on Signal Generator B and operate at the specified operating frequency - frequency deviation.

Adjust the amplitude of Signal Generator B so that at the lowest reception level where the minimum performance of the receiving device is not achieved. Maintain the settings of Signal Generator B, replace the receiver with an appropriate RF power meter. Record the displayed power level of the measuring instrument.

The input overload level of the receiver is the received power level from Signal Generator B at the antenna connector of the Equipment Under Test (EUT).

The input overload level of the receiver may also be measured at the antenna connector for conduction testing or calculated for radiated testing (see C.6.4).

The input overload level of the receiver must be higher than or equal to the input overload power level of the receiver required by the technical requirements.

Step 3:

Steps 1 to 3 measurements are repeated with signal offsets at the required frequencies. Step 4:

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Information in Table 24 is recorded in the test report for the measured signal levels and unwanted signal offsets.

Table 24 - Information recorded in the test report

3. MANAGEMENT PROVISIONS

3.1. Low Power Wide Area Network (LPWAN) devices operating in the 920 MHz to 923 MHz band fall within the scope of this regulation and must comply with the provisions of this standard.

3.2. Testing/measurement for technical requirements in this standard (except 2.4.9) shall be conducted by designated domestic laboratories or recognized foreign laboratories.

3.3. Technical requirements stipulated in 2.4.9 of this standard, organizations and individuals are permitted to use the testing/measurement results from designated domestic laboratories or recognized foreign laboratories, or domestic and foreign laboratories recognized in accordance with ISO/IEC 17025 standards, or the manufacturer's testing/measurement results.

4. RESPONSIBILITIES OF ORGANIZATIONS AND INDIVIDUALS

Relevant organizations and individuals are responsible for implementing regulations on conformity certification and declaration of conformity for LPWAN devices operating in the 920 MHz to 923 MHz band and are subject to inspection by state management authorities according to current regulations.

Chapter 5. ORGANIZATION OF IMPLEMENTATION

5.1. The Telecommunications Authority and Provincial Departments of Information and Communications are responsible for organizing the implementation and managing LPWAN devices operating in the 920 MHz to 923 MHz band according to this standard.

5.2. In cases where the provisions of this standard are changed, supplemented, or replaced, they shall be implemented according to the new document.

5.3. During the implementation of this standard, if any issues arise or difficulties occur, relevant organizations and individuals should reflect them in writing to the Ministry of Information and Communications (Science and Technology Department) for guidance and resolution.

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ANNEX A

Product Name, Goods According to QCVN

Technical characteristics of measurement equipment

A.1. Spectrum Analyzer

The calibrated measurement tool used is a spectrum analyzer. The characteristics of the spectrum analyzer must meet the following requirements:

Frequency marker accuracy must be within ±100 Hz;

Measurement accuracy of attenuation must be within ±3.5 dB;

Dynamic range must exceed 80 dB;

Gaussian RBW filter coefficient ≤ 12;

The spectrum analyzer can be adjusted to allow two equal amplitudes of components with a frequency difference of 100 Hz to be separated on its screen.

For statistical modulation distributions, the spectrum analyzer and integrated equipment (if applicable) must allow the determination of power spectral density (energy over time and bandwidth), which must be integrated over a predetermined bandwidth.

Average phase noise in adjacent and substitute channels must be a measurement of adjacent channel power without being limited by phase noise.

Functions that must be included in a measurement process:

OBW:

ACP;

Linear average power;

Note: Linear averaging is a method of averaging on a spectrum analyzer, wherein the measured power value is the average in the linear power domain.

The substitution method for linear average power is calculated by the formula:

P result = P measured + 2.5 dB

Where P result is the result of P measured taken from the measured value on the spectrum analyzer.

A.2. Signal Generator and Signal Source

It should be noted that the performance of signal generators and signal sources must be sufficient for the tests to be performed. This is particularly important for phase noise.

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Provisions on the HS Code of Terrestrial Mobile Radio Equipment and Terrestrial Radio Relay Equipment

Product Name, Goods According to QCVN

Calibration Kit

B.1. Concept of Calibration Kit

The intended measuring equipment uses an integrated small antenna suitable, without a 50 Ω connection, compatible with the calibration kit shown in Figure B.1.

Fixed measurements are measurements on equipment with a suitable antenna, testing on the radiation signal generated when the calibration kit is performed. To measure unwanted signals in the emission area, the fixed measurement bandwidth will be five times the operating frequency. If not, follow the radiation measurement according to 2.4.2 and Appendix C.

Fixed equipment is radio equipment with a suitable 50 Ω antenna connected for the frequencies to be measured.

Fixed measurements will provide complete information.

Fixed measurements must provide:

a) Connection to a full power supply;

b) Method to provide input or output to the equipment. This includes a suitable antenna. In the case of fast-operating equipment, the audio interface must provide a direct connection or through a mixer, the calibration kit will provide a suitable connection for data or video output.

Typically, the calibration kit is provided by the manufacturer.

Laboratory measurement characteristics will follow the following specifications:

a) Insertion loss of the connection does not exceed 30 dB.

b) Suitable bandwidth.

c) Insertion loss exceeding the measured frequency range does not exceed 2 dB.

d) The circuit with the RF connection will not operate or be non-linear.

e) The VSWR value at 50 Ω must be greater than 1.5 for the required frequency range.

f) Insertion loss must not depend on the position of the calibration kit and must not be affected by people or objects nearby. Insertion loss must be reproducible when the equipment to be measured is moved or replaced.

g) Insertion loss must not change when environmental conditions change.

h) The parameters listed above must satisfy under harsh temperature conditions.

The signal attenuation of the fixed measurement device connection at the measurement point must be greater than the background noise by at least 10 dB. If the attenuation is too high, it can be compensated for by an external linear amplifier outside the measurement box.

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Position of the EU T

50 Ω connector

Figure B.1 - Measurement Box

B.2. Usage Mode

The measurement box mode is commonly used for testing receivers and transmitters when there is an antenna inside the equipment.

Typically, measurements are made of carrier power radiation and sensitivity under varying field strength conditions. Measurements under harsh conditions are performed before calibration in Appendix C.

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Annex C

Product Name, Goods According to QCVN

Measurement position and arrangement for radiation measurements

C.1. Introduction

Three common test areas and a fixed test object will be used in the radiation measurements according to this standard:

Open Area Test Site (OATS);

Semi-Anechoic Chamber (SAR);

Anechoic Chamber (FAR).

The three areas mentioned above are spatial measurements. Both absolute and relative measurements are carried out in these areas. These measurements are described in C.2. C.3 describes the antennas used in these tests. The measurement box is only used for relative value measurements and is described in C.3.

In the case of absolute measurements being performed, the test site needs to be verified. The verification procedure is described in Clause 6 of ETSI TR 102 273-4 for OATS, in Clause 6 of ETSI TR 102 273-3 for SAR, and in Clause 6 of ETSI TR 102 273-2 for FAR. Information on the uncertainty of the measurement on one of these test sites can be found in ETSI TR 100 028-1, ETSI TR 100 028-2, ETSI TR 102 273-2, ETSI TR 102 273-3, and ETSI TR 102 273-4.

C.2. Radiation Measurement Position

C.2.1. OATS

The open area test site includes a rotating table at one end and an adjustable height antenna mast on the other end above a ground plane, ideally infinite and perfectly flat. In practice, while good conductivity may be achieved, the size of the plane must be limited. The extended open area test site (OATS) is illustrated in Figure C.1.

Replaceable Antenna

Measuring Antenna

Figure C.1 - Open Area Test Site (OATS)

The ground plane creates a desired reflective path, such that the signal received by the antenna is the sum of the signals received from direct paths and reflections. The phase of these two signals produces a reception level for each height of the transmitting antenna (or EUT) and receiving antenna above the ground plane. The antenna mast provides a variable height base (from 1 m to 4 m) to optimize the position of the measuring antenna for maximum coupling between the antennas or between the EUT and the measuring antenna. A rotatable table capable of rotating 360° in the horizontal plane is used to support the test sample (EUT) at the specified height, usually 1.5 m above the ground plane. Measurement distance and minimum room size can be found in C.3.4. The actual measurement distance used must be recorded with the test results. Additional information about OATS can be found in ETSI TR 102 273-4.

C.2.2. SAR

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A semi-anechoic chamber (SAR), which is a non-reflective room with a conductive ground plane, typically shielded, has walls and ceilings lined with radio-absorbing material. The floor is metal and not covered with absorbing material, forming the ground plane. It usually contains an antenna mast at one end and a rotating table at the other. A fully non-reflective chamber is illustrated in Figure C.2. This type of test chamber simulates ideal spatial measurements, where its characteristics are equivalent to an infinite waveguide region.

Figure C.2 - Semi-Anechoic Chamber (SAR)

In this model, the ground plane creates a desired reflective path, such that the signal received by the receiving antenna is the sum of the signals received from direct paths and reflections. The phase of these two signals produces a single reception level for each height of the transmitting antenna (or EUT) and receiving antenna above the ground. The antenna mast provides a variable height base (from 1 m to 4 m) to optimize the position of the measuring antenna for maximum coupling between the antennas or between the EUT and the measuring antenna. A rotatable table capable of rotating 360° in the horizontal plane is used to support the test sample (EUT) at the specified height, usually 1.5 m above the ground. Measurement distance and minimum room size can be found in C.3.4. The actual measurement distance used must be recorded with the test results. Additional information about the semi-anechoic chamber can be found in ETSI TR 102 273-3.

A fully anechoic chamber is a completely enclosed, typically shielded room, with walls, floors, and ceilings lined with radio-absorbing material. It usually contains an antenna stand at one end and a rotating table at the other. A fully anechoic chamber is illustrated in Figure C.3.

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Figure C.3 - Fully Anechoic Chamber (FAR)

Shielding materials and radio-absorbing materials work together to provide a controlled environment for testing purposes. This type of test chamber attempts to simulate empty space conditions. Shielding provides a test space, reducing interference from surrounding signals and other external effects, while radio-absorbing materials minimize unwanted reflections from walls and ceilings that could affect the measurement. Shielding must be sufficient to eliminate interference from the external environment, masking all signals to be measured. A rotatable table capable of rotating 360° in the horizontal plane is used to support the EUT at nearly 1.5 m above the ground. Personal-worn devices can be tested using a simulated person as support. The simulated person includes a rotatable acrylic tube filled with saltwater placed on the ground.

Dimensions include:

Height: 1.7 ± 0.1 m;

Internal diameter: 300 ± 5 mm;

Wall thickness: 5 ± 0.5 mm.

The container must be filled with a salt solution (NaCl) at a concentration of 1.5 g per liter of distilled water. The device must be fixed to the surface of the simulated person at an appropriate height for the device.

The container must be filled with a salt solution (NaCl) at a concentration of 1.5 grams per liter of distilled water. The device must be securely attached to the surface of the simulated person at an appropriate height for the device.

NOTE: To reduce the weight of the mannequin, a hollow tube with a maximum diameter of 220 mm may be used. The measurement distance and the minimum size of the room can be found in C.3.4. The actual measurement distances must be recorded with the test results. Additional information on the fully non-reflective room can be found in ETSI TR 102 273-2.

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C.2.4. Measurement Distance

The measurement distance should be chosen to measure the EUT under far-field conditions. The minimum distance between the device and the measuring antenna should be λ or r_m >> D² where:

λ is the wavelength in meters;

r_m is the minimum distance between the EUT and the measuring antenna in meters;

D is the largest physical aperture dimension of the largest antenna in the measurement setup, in meters.

is the distance between the near-field radiation ray and the radiation ray in the Fraunhofer region in meters, known as the Rayleigh distance.

The recommended measurement distance for testing is 3 m or 10 m, where the condition is not met and the distance will be the result of near-field field measurements, which should be recorded in the measurement report and the measurement uncertainty should be recorded in the results.

C.3. Types of Antennas

C3.1. General Requirements

All antennas must be available for measuring the radiation at three positions specified in C.2. Depending on the purpose of the measurement, the antennas will be designed as measuring antennas or substitute antennas.

C.3.2. Measuring Antenna

In emission testing, the measuring antenna detects the electric field of the EUT during a measurement phase or from a substitute antenna in another phase. When the measurement position is used to measure receiver characteristics, the antenna is used as a transmitter.

The measuring antenna should be mounted on a stand that allows it to be used in horizontal or vertical polarization. Additionally, on OATS or SAR, the height of the center of the antenna above ground must vary within the specified range (usually 1 m to 4 m).

At frequencies from 30 MHz to 1 000 MHz, a binary dipole antenna or a logarithmic periodic dipole array (LPDA) antenna should be used. Above 1 GHz, a horn antenna or a log-periodic dipole antenna should be used.

However, for simulated emission tests, a combination of binary and log-periodic dipole arrays can be used to cover the entire frequency band from 30 MHz to 1 000 MHz.

The measuring antenna does not require absolute calibration.

C.3.3. Substitute Antenna

A substitute antenna must be used to replace the tested equipment in substitute measurements.

Compatibility with the frequency band and the level of reflected power of the antenna must be considered when calculating measurement uncertainty.

The phase center of the antenna must coincide with the reference point of the test sample that has been replaced. Therefore, an antenna with a phase center that varies as a function of frequency (LPDA) is not suitable as a substitute antenna.

The reference point of the substitute antenna must coincide with the center of the EUT when its antenna is inside or at the point where the external antenna connects to the EUT.

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The minimum distance between the lower end of the antenna and the ground is 30 cm.

The substitute antenna must be calibrated. Below 1 GHz, relative calibration with a half-wave dipole is required, while above 1 GHz, an isotropic radiator serves as the reference.

NOTE: Calibration data intended for use above a reflective surface in a non-reflective chamber or vice versa cannot be used.

C.4. Guidance for Setting Measurement Points

C.4.1. General Requirements

Specific procedures, typically involving appropriate measurement equipment, must be carried out before radiation emission measurements. These diagrams are common for all test positions described in C.2.

If necessary, a mounting frame with a minimum size to mount the EUT on a turntable must be provided. The frame should be made of low-conductivity material, such as polystyrene, ...

C.4.2. Power Supply to the EUT Using Batteries

All measurements using battery-powered sources, including those on EUTs designed to use batteries, must be conducted. For battery-operated devices, the power supply cable must be connected to the EUT's power connector (and monitored by a digital voltmeter) but the battery itself must remain isolated from the rest of the device, possibly by taping over its contacts.

Cables can affect the measurement performance of the EUT. Therefore, measures must be taken to avoid this impact. This can be achieved by routing them away from the EUT as well as running them under the floor or along the wall by the shortest possible route. Precautions should be taken to minimize the influence of these cables.

C.4.3. Preparation of Position

Cables to the measuring and substitute antennas should be arranged horizontally at least 2 m away from the measurement area (unless, in both types of non-reflective chambers, they are placed close to the wall) and allow for vertical and through-the-floor or table-top (if applicable) measurements for the test equipment. Measures must be taken to minimize the impact of cables. Cables, wiring, and shielding must meet the standards for measurement.

Calibration data for all components of the measurement equipment must be available and valid. For test antennas and substitute antennas, the data must include the gain factor relative to an isotropic radiator (or antenna factor) for the test frequency. Additionally, the VSWR factor of the substitute antenna and the measuring antenna must be determined.

Calibration data for all cables and attenuators must include the attenuation factor and VSWR across the entire test frequency band. All attenuation and VSWR data must be recorded in the measurement report.

When correction factors for the main calibration are required, they must be immediately available.

For all components of the test equipment, the maximum errors and error margins must be determined. For example:

Cable loss: ±0.5 dB with a rectangular distribution;

Receiver measurement: signal level accuracy of 1.0 dB (standard deviation) with a Gaussian error distribution.

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During measurement, system checks must be performed on all components of the test equipment.

C.5. Signal Combining

C.5.1. General Requirements

Radiation fields may cause electromagnetic interference and lead to measurement uncertainty. This noise can be reduced by using appropriate signal combining methods, signal splitters, and noise reduction techniques.

C.5.2. Data signals

The isolation level can be achieved using optical, ultrasonic, or infrared methods. To reduce interference in the field, appropriate optical cable connections may be used. Ultrasonic or infrared radiation connections require suitable measures to minimize surrounding interference.

C.6. Measurement Process for Radiation

C.6.1. General Requirements

This annex provides general procedures for radiation measurements at test locations, arranged according to the guidelines in Annex C. Radiation measurements should ideally be conducted in the Far Field Region (FAR), as described in C.7.3. Radiation measurements in Over-The-Air Test System (OATS) or Semi-Anechoic Room (SAR) are detailed in C.7.2.

C.6.2. Radiation Measurement on OATS or SAR

The radiation measurement will be supported by additional measurement antennas and recommended antennas in Section C.2 and test positions in Section C.1. The Equipment Under Test (EUT) and measurement antenna are set up to achieve maximum transmission power. This position will be recorded in the test report:

a) The measurement antenna is set up with vertical polarization unless otherwise specified, and the EUT is placed at the standard position and turned on.

b) The measuring equipment is connected to the measurement antenna and configured according to the test specifications.

Figure C.4 - Measurement Setup - Method 1

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2. Measurement Antenna

3. Measuring Equipment

c) The EUT is rotated 360 degrees in the horizontal plane until the largest signal is received from the measuring equipment.

d) The measurement antenna must be raised or lowered within the specified height range until the maximum level is reached. This level will be recorded.

e) The measurement is reset with a horizontally polarized antenna.

NOTE: The maximum level may have a lower value than that which could be achieved at heights outside the recommended range.

C.6.3. Radiation Measurement in FAR

For radiation measurements using the Far Field Region (FAR), the process follows the procedure described in C.7.2.

C.5.4. Alternative Measuring Equipment

To determine absolute measurement values, alternative measurements will be performed. The steps are as follows:

a) Replace the EUT with the alternative antenna described as device 1 (EUT) in Figure C.4. The antennas used are vertically polarized antennas.

b) Connect the standard signal generator to the alternative antenna and adjust it to the measurement frequency.

c) If OATS or SAR is used, the measurement antenna will be raised or lowered to ensure the highest signal level is obtained.

d) Then, the signal generator's power will be adjusted to match the reception level at the measuring equipment as if it were the EUT.

e) Radiated power equals the power provided by the signal generator, increased by the antenna gain to compensate for cable loss (expressed in dB).

1) The measurement is repeated with a horizontally polarized antenna.

NOTE: For test positions where the antenna must be fixed and the position repeated with different EUTs, calibration position correction values may change.

C.6.5. Radiation Measurements for Receivers

Radiation measurements must be conducted in the Far Field Region (FAR). Receiver measurements are essentially the reverse of transmitter measurements, with a signal generator connected to the measurement antenna. Calibration is based on replacing the EUT with an alternative antenna and appropriate measuring equipment. For C.3.3, use an alternative antenna.

NOTE: This does not require a half-wave dipole, only an antenna with half-wave gain.

There are two methods:

a) Connect the alternative antenna to the calibrated receiver and read the direct measurement results.

b) Measure the path loss from the measurement antenna to the alternative antenna and subtract this from the signal reception level of the signal generator to obtain the measurement result.

For method a), the received level in the measurement log may be too low, so it may be necessary to increase the signal generator's signal appropriately and apply equivalent compensation levels to achieve the measurement result.

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For method b), this is a calibration measurement that can be used for multiple tests.

C.7. Technical Requirement Guidelines for Testing

C.7.1. General Requirements

This Section provides guidance on various technical measurement requirements for radiation measurements.

C7.2. Position for measuring compliant radio signal and compliance

Table C.1 sets out the measurement positions for each radio measurement when performing radiation measurements on devices with integrated antennas.

Table C.1 - Reference for wireless measurement tests and measurement methods

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Appendix D

Product Name, Goods According to QCVN

HS code for low-power wide-area network (LPWAN) radio equipment in the 920 MHz to 923 MHz band

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Bibliography

[1] ETSI EN 300 220-1 V3.1.1 (02-2017): "Short Range Devices (SRD) operating in the frequency range 25 MHz to 1 000 MHz; Part 1: Technical characteristics and methods of measurement".

[2] ETSI EN 300 220-2 V3.2.1 (2018-06) "Short Range Devices (SRD)"

in the frequency range 25 MHz to 1 000 MHz; Part 2: Harmonised Standard for access to radio spectrum for non-specific radio equipment".

[3] ITU-R Report SM.2423-0 (2018-06) "Technical and operational aspects of low power wide area networks for machine-type communication and the Internet of Things in frequency ranges harmonised for SRD operation".

[4] ITU-R Recommendation SM.329-12 (09/2012) "Unwanted emissions in the spurious domain".

[5] Regulation No. 3/2019 LPWAN (Indonesia).

[6] Class Assignment No. 1-2017 (Malaysia).

(7) IMDA TS SRD Issue 1 Revision 1, 4/2018 (Singapore).