Circular No. 27/2016/TT-BTTTT Issuing the "National Technical Regulation on Radio Equipment for Ground-based Mobile Aviation Services in the 117.975-137 MHz Band Using Amplitude Modulation (AM)

 

CIRCULAR

ISSUING THE NATIONAL TECHNICAL REGULATION ON RADIO EQUIPMENT FOR AERONAUTICAL MOBILE SERVICES USING AMPLITUDE MODULATION IN THE FREQUENCY BAND 117,975-137 MHz ON GROUND

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;

Based on Decree No. 132/2013/ND-CP dated October 16, 2013 of 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,

AND trưởnThe Ministry of Information and Communications issues this Circular to regulate the national technical standards for radio equipmentpoliciesin aeronautical mobile services organize credit institutions, foreign bank branches are responsible for organizing the implementation of this Circular.using amplitude modulation in the frequency band 117,975-137 MHz on ground.

Article 1. This Circular promulgates the National Technical Regulation on radio equipment for aeronautical mobile services using amplitude modulation in the frequency band 117,975-137 MHz on ground (QCVN 105:2016/BTTTT).

Article 2. This Circular takes effect from July 1, 2017.

Article 3. The Director of the Office, Heads of Science and Technology Department, Heads of agencies and units under the Ministry of Information and Communications, Directors of Provincial Departments of Information and Communications, and relevant organizations and individuals are responsible for implementing this Circular./.

 

QCVN 105:2016/BTTTT

NATIONAL TECHNICAL REGULATION ON RADIO EQUIPMENT FOR AERONAUTICAL MOBILE SERVICES USING AMPLITUDE MODULATION IN THE FREQUENCY BAND 117,975-137 MHz ON GROUND

National technical regulation on ground-based radio equipment for aeronautical mobile CLASS MONOCOTYLEDONservice using amplitude modulation in the frequency band 117,975-137 MHz

 

TABLE OF CONTENTS

Chapter 1. GENERAL PROVISIONS

1.1. Scope of Application

1.2. Applicability

1.3. Referenced Documents

1.4. Terms and Definitions

1.5. Abbreviations

Chapter 2. TECHNICAL PROVISIONS

2.1. Provisions for the transmitter

2.1.1. Frequency error

2.1.2. Carrier power (conducted)

2.1.3. Adjacent channel power

2.1.4. Spurious emissions

2.1.5. Modulation distortion (This requirement applies only to ground-based base station equipment)

2.1.6. Transmitter's transition frequency characteristic (This requirement applies only to ground-based base station equipment)

2.1.7. Enclosure radiation

2.2. Provisions for the receiver

2.2.1. Sensitivity

2.2.2. Adjacent channel selectivity

2.2.3. Desensitization

2.2.4. Demodulation distortion

2.2.5. Blocking

2.2.6. Receiver spurious emissions

2.2.7. Demodulation suppression

2.2.8. Enclosure radiation

3. MEASUREMENT METHODS

3.1. Measurement environmental conditions

3.1.1. Normal measurement conditions

3.1.2. Measurement power supply

3.1.3. Normal measurement conditions

3.1.4. Performance testing

3.2. General conditions

3.2.1. Signal preparation for the receiver

3.2.2. Signal preparation for the transmitter

3.2.3. Measurement channel

3.3. Interpretation of measurement results

3.4. Measurement methods

3.4.1. Measurement for the transmitter

3.4.1.1. Measurement of frequency error

3.4.1.2. Measurement of carrier power (conducted)

3.4.1.3. Measurement of adjacent channel power

3.4.1.4. Measurement of spurious emissions

3.4.1.5. Measurement of modulation distortion

3.4.1.6. Measurement of transmitter's transition frequency characteristic

3.4.1.7. Measurement of enclosure radiation

3.4.2. Measurement for the receiver

3.4.2.1. Measurement of sensitivity

3.4.2.2. Measurement of adjacent channel selectivity

3.4.2.3. Measurement of desensitization

3.4.2.4. Measurement of demodulation distortion

3.4.2.5. Measurement of blocking

3.4.2.6. Measurement of receiver spurious emissions

3.4.2.7. Measurement of demodulation suppression

3.4.2.8. Measurement of enclosure radiation

4. PROVISIONS Oề MANAGEMENT

5. RESPONSIBILITIES OF Tis a communicable disease or parasite listed by the Ministry OFFICIAL, INDIVIDUAL

16. Hot water bottles and electric water heaters of various types.is a communicable disease or parasite listed by the Ministry IMPLEMENTATION

LIST OF REFERENCED DOCUMENTSGENERAL PROVISIONSO

 

Foreword

QCVN 105:2016/BTTTT is based on the European Telecommunications Standards Institute (ETSI) standard ETSI EN 300 676-2 V1.5.1 (2011-09).

QCVN 105:2016/BTTTT was compiled by the Telecommunications Administration, reviewed and approved by the Science and Technology Department, and issued together with Circular No. 27/2016/TT-BTTTT dated December 7, 2016.

 

NATIONAL TECHNICAL REGULATION ON RADIO EQUIPMENT FOR AERONAUTICAL MOBILE SERVICES USING AMPLITUDE MODULATION IN THE FREQUENCY BAND 117,975-137 MHz Z ON GROUND USING AMPLITUDE MODULATION

National technical regulation on ground-based radio equipment for the aeronautical mobile CLASS MONOCOTYLEDONservice using amplitude modulation in the frequency band 117,975-137 MHzThis regulation applies to full-carrier double-sideband amplitude modulation (DSB AM) radio transmitters and transceivers operating in the Very High Frequency (VHF) band with channel spacing of either 8.33 kHz or 25 kHz for analog voice communication for ACARS.

Chapter 1. GENERAL PROVISIONS

1.1. Scope of Application

The scope of this regulation covers ground-based base stations, mobile units, portable units, and handheld units operating within all or part of the frequency band from 117.975 MHz to 137 MHz.

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

1.2. Applicability

QCVN 42:2011/BTTTT, National Technical Regulation on Portable Ground-Based Radio Equipment with Detachable Antennas for Data Transmission (and Voice Communication).

1.3. Referenced Documents

ICAO Annex 10 Volume V (6/2001): "Aeronautical Radio Frequency Spectrum Utilization".

ITU-T Recommendation 0.41: "Psophometer for use on telephone-type circuits".

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".

1.4.1. Aeronautical mobile service

1.4. Terms and Definitions

(aeronautical mobile service) The mobile service between aeronautical stations and aircraft stations or between aircraft stations, including emergency beacons and emergency locating transmitters, may also participate in this service on distress and safety frequencies.

1.4.2. Conducted measurements

(conducted measurements) Measurements performed by direct RF connection to the device under test.

1.4.3. Environmental conditions

(environmental profile) The range of environmental conditions that equipment within the scope of this technical regulation must comply with.

1.4.4. Ground-based base station

(ground base station) A base station used in the aeronautical mobile service, equipped with external antennas and located at a fixed position on the ground.

1.4.5. Handheld equipment

(hand held) A radio device powered by batteries, designed to be carried and operated by hand.

1.4.6. Integral antenna equipment

(integral antenna equipment) A radio communication device with an integral antenna inside the device without external connections, where the antenna is considered part of the equipment.

NOTE: The integral antenna may be mounted inside or outside the equipment. For such equipment, there must be an RF 50 ohm connection point, an audio frequency (AF) input point, and an AF output point for testing purposes.

1.4.7. Mobile station

(mobile station) (mobile station)

Radio equipment designed, installed, and operated either permanently or temporarily on vehicles, powered from vehicle DC sources, connected to external antennas, using push-to-talk keys, microphones, speakers, and/or headsets.

1.4.8. Non-integral antenna equipment (non-integral antenna equipment)

Radio communication equipment with a connector for connecting to an antenna.

1.4.9. Portable equipment (portable station)

Portable radio equipment using battery power that can be used independently and carried by hand.

NOTE: External antenna connectors, push-to-talk keys, microphones, headsets, and chargers may be provided. However, it primarily operates as an independent unit and is pre-integrated.

1.4.10. Radiated measurements (radiated measurements)

Measurements related to the measurement of a radiation field.

1.4.11. Impedance coupling devicein When testing is performed with a coaxial cable end having a 50 ohm load that does not radiate and does not reflect. 1.4.12. Keyline

Channel switching component.

1.4.13. Carrier offset system

(carrier offset system)

A multi-station multi-frequency transmission system within the receiver bandwidth. ACARS

Aircraft Communication Addressing and Reporting System

1.5. Abbreviations

Chapter 2. TECHNICAL PROVISIONS

2.1. Provisions for the transmitter

2.1.1. Frequency error

2.1.1.1. Definition

Frequency deviation (ppm)

Ground station (8.33 kHz)

Mobile/portable (8.33 kHz)

Handheld (8.33 kHz)

Under normal test conditions, the maximum output carrier power (unmodulated) shall not deviate more than ±1.5 dB from the maximum rated output power.

2.1.2.3. Measurement methods

2.1.2. Carrier power (conducted)

2.1.2.1. Definition

Use the measurement methods described in 3.4.1.2

Adjacent channel power is a portion of the total output power of the transmitter under defined modulation conditions, which lies within the adjacent channel bandwidth centered on the nominal frequency of one of the two adjacent channels. This power is the sum of the average modulated, noise, and interference power of the transmitter.

2.1.3.2. Limits

The adjacent channel power must be lower than the carrier power of the transmitter by at least the following:

- For channel spacing 8.33 kHz: 50 dB;

- For channel spacing 25 kHz: 60 dB.

2.1.3. Adjacent channel power

2.1.3.1. Definition

2.1.3.3. Measurement methods

Use the measurement methods described in 3.4.1.3

2.1.4.1. Definition

Spurious emissions are emissions appearing at the RF output port on one or more frequencies outside the necessary bandwidth, and the magnitude of these emissions can be reduced without affecting the corresponding information transmission. Spurious emissions include harmonic emissions, parasitic emissions, cross-modulation components, and frequency conversion products, but do not include out-of-band emissions.

2.1.4.2. Limits

The power of any spurious emission shall not exceed the values given in Table 2 below.

Table 2 - Spurious Emissions

2.1.4. Spurious emissions

Environmental phenomenon

Frequency range

Limit, Tx (standby state)

Limit, Tx (operational state)

Bandwidthn l of

Cross-modulation suppression is determined as the ratio between the power level of the third-order intermodulation component and the power level of the carrier, expressed in dB.

2.1.5.2. Limits

The minimum modulation protection factor must be 40 dB.无效 2.1.5.3. Measurement methods

Use the measurement methods described in 3.4.1.5

2.1.6. Transient frequency characteristics of the transmitter (This requirement applies to ground station equipment only)

2.1.6.1. Definition

The transient frequency characteristics of the transmitter are caused by the wideband response due to keyline switching.

2.1.6.2. Limits

The minimum transient attenuation is 30 dB below the reference level measured at a frequency 10 kHz away from the carrier frequency.

2.1.6.3. Measurement methods

Use the measurement methods described in 3.4.1.6 q2.1.7.1. Limits

2.1.6.1. Definition

The frequency overshoot characteristics of the transmitter due to the wideband response caused by the shift of the keyline.

2.1.6.2. Limit

The minimum overshoots must be 30 dB below the reference level measured at a frequency 10 kHz away from the carrier frequency.

2.1.6.3. Measurement Method

Use the measurements described in 3.4.1.6

2.1.7. Enclosure radiation

2.1.7.1. Limit

The radiation of the transmitter shell must comply with the requirements set out in Section 2.2.5 of QCVN 42: 2011/BTTTT.

2.1.7.2. Measurement Method

Use the measurements described in 3.4.1.7

2.2. Provisions for the receiver

2.2.1. Sensitivity

2.2.1.1. Definition

The receiver sensitivity is the signal level at the rated frequency at the receiver input, under normal measurement conditions (see Section 3.2.1.3), this signal level will produce:

- In all cases, the minimum audio output power shall be 50% of the rated output power (see Section 3.2.1.5) and

- The SINAD ratio = 12 dB, measured at the receiver output through a voice noise measuring circuit as recommended in ITU-T Recommendation O.41.

2.2.1.2. Limitations

The maximum sensitivity shall not exceed -101 dBm under normal measurement conditions.

2.2.1.3. Measurement Method

Use the measurements described in 3.4.2.1

2.2.2. Adjacent channel selectivity

2.2.2.1. Definition

Adjacent channel selectivity is the ability of the receiver to obtain the desired modulated signal without degradation exceeding a given threshold due to the presence of an undesired modulated signal, offset from the desired signal frequency by 8.33 kHz or 25 kHz.

2 2.2.2. Limitations

The adjacent channel selectivity must be greater than 60 dB.

2.2.2.3. Measurement Method

Use the measurements described in 3.4.2.2

2.2.3. Desensitization

2.2.3.1. Definition

Image rejection is the ability of the receiver to distinguish between the desired modulated signal at the rated frequency and an undesired signal at any frequency within the reception bandwidth.

2.2.3.2. Limitations

At any frequency offset from the receiver's rated frequency by two or more channel spacings, the image rejection shall not be less than 70 dB.

2.2.3.3. Measurement Method

Use the measurements described in 3.4.2.3

2.2.4. Demodulation distortion

2.2.4.1. Definition

Intermodulation rejection is the ability of the receiver to receive a desired modulated signal at the rated frequency without degradation exceeding a given threshold due to the presence of multiple undesired signals having specific frequency relationships with the desired signal frequency.

2.2.4.2. Limitations

The intermodulation rejection ratio must

- Be greater than 70 dB for ground-based station equipment operating with wideband channels of 8.33 kHz and 25 kHz.

- Be greater than 64 dB for mobile, portable, and handheld equipment operating with wideband channels of 8.33 kHz and 25 kHz.

2.2.4.3. Measurement Method

Use the measurements described in 3.4.2.4

2.2.5. Blocking

2.2.5.1. Definition

Desensitization is the measure of the receiver's ability to receive the desired modulated signal without exceeding a given degradation threshold due to the presence of an undesired signal at any frequency other than the image frequency or the frequencies of adjacent channels.

2.2.5.2. Limitations

The desensitization ratio at any frequency within specified frequency bands shall not be lower than 80 dB for ground-based station equipment and not lower than 70 dB for mobile, portable, and handheld equipment.

2.2.5.3. Measurement Method

Use the measurements described in 3.4.2.5

2.2.6. Receiver spurious emissions

Customer assistance service is a service that provides answers to inquiries, advice, guidance on using the service, accepts requests, and provides information to customers about IPTV services on the fixed terrestrial telecommunications network.

Spurious emissions are components at any frequency emitted from the receiver and its antenna port. The magnitude of spurious emissions is measured by their power levels at the antenna connection port.

2.2.6.2. Limitations

The magnitude of any spurious emission shall not exceed the values in Table 3

Table 3 - Spurious emissions at the receiver section

2.2.6.3. Measurement Method

Use the measurements described in 3.4.2.6

2.2.7. Demodulation suppression

2.2.7.1. Definition

Intermodulation is the transfer of the AM component from a strong undesired signal to the desired signal.

Intermodulation suppression is the difference between the undesired signal and the highest sensitivity (as defined in Section 2.2.1) at the point where the components caused by intermodulation reduce the SINAD ratio of the desired signal to 20 dB.

2.2.7.2. Limitations

The intermodulation suppression ratio shall not be lower than 80 dB for ground-based station equipment and not lower than 70 dB for mobile, portable, and handheld equipment.

2.2.7.3. Measurement Method

Use the measurements described in 3.4.2.7

2.2.8. Enclosure radiation

2.2.8.1. Limitations

The receiver shell radiation must comply with the requirements set out in Section 2.3.7 of QCVN 42: 2011/BTTTT.

2.2.8.2. Measurement Method

Use the measurements described in 3.4.2.8

3. MEASUREMENT METHODS

3.1. Measurement environmental conditions

3.1.1. Normal measurement conditions

The measurements must be performed under normal conditions.

3.1.2. Measurement power supply

Throughout the measurement process, the device must be powered from a power source capable of generating normal test voltages.

The internal impedance of the test power source must be sufficiently low to have an insignificant effect on the measurement results. During testing, the voltage of the test power source between the two power supply inputs of the device must be measured.

Throughout the measurement process, the test power source voltage must be maintained within a tolerance of less than ±3% compared to the initial voltage at the start of each measurement.

3.1.3. Normal measurement conditions

3.1.3.1. Normal Humidity and Temperature

The normal temperature and humidity conditions for measurement are any combination of temperature and relative humidity within the following ranges:

Temperature: 15 °C to 35 °C

Relative Humidity: 20% to 75%

When it is not possible to perform the measurement under the above conditions, record the ambient temperature and relative humidity during the measurement, and include this information in the measurement results.

3.1.3.2. Normal Test Power Supply Conditions

a) Grid Power

The normal test voltage for devices connected to grid power must be the nominal grid power voltage. For the purposes of this standard, the nominal voltage must be the published voltage or any value within the design range published for the device. The frequency of the test power supply corresponding to AC grid power must be within the range of 49 Hz to 51 Hz.

b) Common Car Battery

When the radio equipment operates on a common car lead-acid battery, the normal test voltage is 1.1 times the nominal battery voltage (for example, 6 V; 12 V...).

c) Other Power Supplies

When the equipment operates with other power supplies or types of batteries (primary or secondary), the normal test voltage must be the voltage published by the equipment manufacturer.

3.1.4. Performance testing

For the purpose of this standard, the term "Measurement and Limitation of Performance" shall mean the measurements and limitations as follows:

- For transmitters:

+ Frequency error: For transmitters connected to impedance matching equipment, frequency error is defined as per Section 2.1.1.

+ Carrier power: For transmitters connected to impedance matching equipment, the transmitter must be locked without modulation and the output power must comply with Section 2.1.2.

+ Modulation: For transmitters connected to impedance matching equipment, the transmitter must be locked without modulation.

- For receivers:

+ Reception sensitivity: With AGC, a normal test signal (see Section 3.2.1.3) will be supplied to the receiver. Reception sensitivity is defined as per Section 2.2.1.

3.2. General conditions

3.2.1. Signal preparation for the receiver

3.2.1.1. Test Signal Source

The test signal source is connected to the receiver input where the input impedance is 50 ohms, regardless of whether one or multiple test signals are supplied to the receiver simultaneously.

3.2.1.2. Nominal Frequency

The nominal frequency of the receiver is the carrier frequency of the selected channel.

3.2.1.3. Normal Test Signal

A normal test signal is a double-sideband full-carrier (DSB) signal modulated with an amplitude-modulated (AM) sine wave of 1 kHz at a depth of 30%.

3.2.1.4. Normal Speech Output Power

The nominal speech output power is the maximum power value at the output published by the manufacturer, all requirements of this standard being met.

The speech output power is maintained at 50% of the nominal output power specified in this standard with the described signal, except as otherwise provided.

3.2.1.5. AGC Sound

When an AGC sound function is provided, this function must be turned off (if possible) unless otherwise specified.

3.2.2. Signal preparation for the transmitter

3.2.2.1. Coaxial Cable End

When testing is performed with a coaxial cable section with an impedance of 50 ohms, non-radiating and non-reflection.

3.2.2.2. Signal Source

The modulated signal will be supplied to the transmitter through the voice signal input modulation.

3.2.2.3. Normal Test Signal

A normal test signal is a 1 kHz sine wave with a 30% modulation depth at the transmitter, except as otherwise specified.

3.2.3. Measurement channel

Testing is conducted on the following three frequencies unless otherwise specified:

- 118 MHz;

- 127.5 MHz;

- 136.975 MHz.

3.3. Interpretation of measurement results

Interpretation of results recorded in the test report for the measurements in this standard is as follows:

- Compare the measured values with the corresponding limits to determine if the equipment meets the minimum required parameters in this standard.

- For each specific measurement, the actual measurement uncertainty must be recorded in the test report.

- For each measurement, the measurement uncertainty value must be equal to or less than the values in Table 4.

For the measurement methods in this technical standard, calculation of measurement uncertainty values complies with TR 100 028 V1.4.1 with an expansion factor of k = 1.96 or k = 2 (these factors correspond to confidence levels of 95% and 95.45%, respectively, in the case of a normal distribution (Gaussian) of actual measurement uncertainties).

Table 4 is based on these expansion factors.

Table 4 - Maximum Values of Measurement Uncertainty

For the measurement methods in this standard, the measurement uncertainties have a confidence level of 95% according to the method described in TR 100 028 V1.4.1.

3.4. Measurement methods

3.4.1. Measurement for the transmitter

3.4.1.1. Measurement of frequency error

The carrier frequency must be measured unmodulated, the transmitter will be connected to impedance matching equipment. Measurements must be carried out under normal test conditions (see Section 3.1.3) at 127.5 MHz.

3.4.1.2. Measurement of carrier power (conducted)

Figure 1 - Diagram for measuring carrier power

The transmitter is connected to the impedance matching equipment and the transmission power will be measured at the output.

Measurements are carried out under normal test conditions (see Section 3.1.3) for the highest and lowest output power levels of the transmitter. Measurements must be carried out on the test channels (see Section 3.2.3).

3.4.1.3. Measurement of adjacent channel power

Figure 2 - Diagram for measuring adjacent channel power

Adjacent channel power can be measured using a power receiver or an equivalent analyzer here referred to as "receiver meter."

a) The transmitter must be activated at the maximum carrier power specified in Section 2.1.2 under normal test conditions. The transmitter output must be connected to the "receiver meter" input via a connection device such that the impedance for the transmitter is 50 ohms and the level at the "receiver meter" input is appropriate;

b) The transmitter must be modulated with a signal at 1 kHz for a channel width of 8.33 kHz and 25 kHz with a modulation depth requirement of 85%;

c) With the modulated transmitter signal, the "receiver meter" tuning circuit must be adjusted to achieve maximum response. This is the 0 dB point. The attenuation set for the "receiver meter" and the reading on the meter must be recorded;

d) The "receiver meter" must be tuned away from the carrier frequency so that the -6 dB point of the "receiver meter" closest to the transmitter carrier frequency is located at a shift from the nominal carrier frequency of 4.83 kHz (channel spacing 8.33 kHz) or 17 kHz (channel spacing 25 kHz);

e) The variable attenuator of the "receiver meter" must be adjusted to obtain the same reading on the meter as in step c) or a known relationship with that reading;

f) The ratio of adjacent channel power to carrier power is the difference between the attenuations set in steps c) and e), corrected for any difference from the meter readings;

g) The measurement must be repeated with the "receiver meter" tuned to the other side of the carrier frequency.

3.4.1.4. Measurement of spurious emissions

a) Spurious emissions must be measured with the transmitter without a modulated signal connected to the impedance matching equipment and operating at the central test frequency (see Section 3.2.3).

b) The measurements must be carried out across the frequency band from 9 kHz to 4 GHz, excluding channels on which the transmitter is operating and within 1 MHz of the center frequency.

c) The measurements for each spurious emission must be performed using a radio measuring instrument that has been calibrated or a spectrum analyzer.

d) The measurements must be repeated with the transmitter in standby mode.

3.4.1.5. Measurement of modulation distortion

Figure 3 - Diagram of modulation loss measurement

a) The test setup is shown in Figure 3.

b) Connect the transmitter to a 10 dB power attenuator with 50 Ω impedance and to the spectrum analyzer via a directional coupler (isolator). An additional 20 dB power attenuator with 50 Ω impedance may be required between the directional coupler (isolator) and the spectrum analyzer to avoid overload.

c) To minimize the impact of measurement errors, the 10 dB power attenuator must be connected to the transmitter under test with the shortest possible cable.

d) The noise signal source is connected to the other side of the directional coupler through a 20 dB power attenuator with 50 Ω impedance.

e) The noise signal source can be a transmitter of the same type and power level as the transmitter under test or a signal generator and a linear power amplifier capable of delivering the same output power as the transmitter under test.

f) The directional coupler (isolator) must have a coupling loss lower than 1 dB. If used, the directional coupler must have sufficient bandwidth and a directivity of at least 20 dB.

g) The transmitter under test and the noise signal source must be physically separated so that the measurement is not affected by direct radiation.

h) The transmitter under test must not be modulated and the spectrum analyzer must be adjusted to display the maximum with a frequency sweep width of 500 kHz.

i) The noise signal source must not be modulated and its frequency must be higher than the frequency of the transmitter under test by 150 kHz to 200 kHz.

j) Select frequencies such that the measured modulation products do not overlap with other unwanted components.

k) Adjust the output power of the noise signal source to match the carrier wave power of the transmitter under test using a power meter.

I) Measure the modulation product component by directly observing on the spectrum analyzer the ratio of the largest third-order intermodulation component to the carrier wave. Record this value.

m) Repeat this measurement with the noise signal source set at a frequency lower than the frequency of the transmitter under test by 150 kHz to 200 kHz.

3.4.1.6. Measurement of transmitter's transition frequency characteristic

Hình 4 - Diagram of the over-frequency characteristic measurement of the transmitter

a) The transmitter must be connected through a 50 Ω impedance matching network capable of reducing the RF power to a safe level for the spectrum analyzer.

b) The transmitter must be set to a frequency of 118 MHz and modulated by a 1 kHz subcarrier signal with a modulation depth of approximately 85%.

c) The spectrum analyzer will be adjusted to the nominal frequency of the transmitter and expanded to 100 kHz with a bandwidth of 1 kHz.

d) The transmitter is locked and the spectrum analyzer settings are adjusted to display the central frequency response at the reference level (using the hold maximum function), with at least 60 dB within the operating range.

e) The keyline of the transmitter is then controlled by an appropriate switching signal, allowing the transmitter to switch at a rate of at least 5 Hz.

f) The spectrum analyzers are set to hold maximum and the keyline switches at a rate of at least 2 minutes.

g) The display of the spectrum analyzer will be recorded.

h) Repeat for all test channels (see Section 3.2.3).

3.4.1.7. Measurement of enclosure radiation

The measurements of the transmitter housing radiation are specified in Section 2.2.5 of QCVN 42: 2011/BTTTT.

3.4.2. Measurement for the receiver

3.4.2.1. Measurement of sensitivity

a) A normal test signal (see Section 3.2.1.3) at a carrier frequency equal to the nominal frequency of the receiver will be applied to the receiver input. A sound frequency and a measuring device to measure the SINAD ratio (through a noise bridge circuit) are connected to the receiver output.

b) The level of the test signal is adjusted until the SINAD ratio is 12 dB, using the noise bridge circuit and adjusting the receiver's audio output level to produce 50% of the rated output power. Under these conditions, the level of the test signal at the input is the maximum sensitivity value.

c) The measurements are performed under normal test conditions (see Section 3.1.3).

d) The receiver's output power varies ±3 dB corresponding to 50% of the rated output power. The measurements are performed on all test channels (see Section 3.2.3).

3.4.2.2. Measurement of adjacent channel selectivity

a) The measurements must be carried out on all test channels (see Section 3.2.3).

b) Two input signals from signal generators G1 and G2 will be applied to the receiver input through a combiner circuit. A telephone analyzer is connected to the receiver outputs through a noise bridge filter.

c) Turn off signal generator G2, and the desired test signals from G1 at the receiving frequencies must be set to produce a modulation depth of 60% at 1 kHz.

d) Adjust the level of G1 to achieve a SINAD number of 12 dB at the receiver outputs. This level will be considered Level 1.

e) Repeat the measurement but this time turn off G1 and adjust G2, modulating at 60% at 1 kHz, to achieve a SINAD value of 12 dB at the receiver outputs. This level will be considered Level 2.

f) Turn on signal generator G1. Set G2 to a frequency of a higher channel division than the nominal frequency of the receiver and apply modulation at 400 Hz with a modulation depth of 60%.

g) The amplitude of the unwanted signal will be adjusted until the SINAD ratio at the receiver output drops to 6 dB. This level will be considered Level 3.

h) The adjacent channel selectivity is the difference between Level 3 and Level 2.

i) The measurement must be repeated with the unwanted signal (G2) on a lower channel than the desired signal.

j) The adjacent channel selectivity measurement is recorded as the minimum difference of the measurement between the upper and lower adjacent channels.

3.4.2.3. Measurement of desensitization

False responses may occur at all frequencies within the frequency spectrum, and the requirements set forth in this standard must be met at all frequencies. For practical reasons, however, measurements only need to be conducted as specified in this standard. Specifically, this measurement method does not require testing with all false responses but rather selects those that are most likely to occur. However, within a limited frequency band near the receiver's nominal frequency, the receiver cannot reliably determine false responses, and thus the determination is made within a limited frequency range. This method is highly reliable, and the equipment also meets the requirements at frequencies that are not measured.

3.4.2.3.1. Frequency Limit Search Method

a) The normal test signal is used (see Section 3.2.1.3).

b) The test signal will be adjusted to a level corresponding to a SINAD ratio of 12 dB through a noise filter and considered as the reference level.

c) The input test signal level is then adjusted to 80 dB relative to the reference level.

d) Frequencies are continuously varied within the frequency limit and outside the appropriate frequency band.

e) The frequency of any false response detected during the search process shall be recorded for use in subsequent measurements described in the following sections.

3.4.2.3.2. Measurement Method

a) A test signal from a signal generator shall be applied to the receiver input. An RMS voltmeter must be connected to the receiver output through a noise filter.

b) The test signal is a normal test signal (see Section 3.2.1.3) at the receiver's nominal frequency.

c) The RF signal level is adjusted to produce a SINAD ratio of 12 dB, and this RF level is recorded as the reference level.

d) The signal generator is then adjusted to a false response frequency identified according to Section 3.4.2.3.1 and modulated with a normal test modulation.

e) The RF signal level is increased until the receiver output signal produces a SINAD ratio of 12 dB.

f) This RF signal level is recorded as the unwanted signal level.

g) The false response suppression ratio is the dB ratio of the unwanted signal level to the reference signal level.

h) This measurement must be performed for each frequency specified in Section 3.4.2.3.1.

3.4.2.4. Measurement of demodulation distortion

a) The desired signal from Signal Generator A must be at the receiver's nominal frequency and modulated with a normal test signal (see Section 3.2.1.3) and applied to the receiver inputs through a combiner circuit.

b) Unwanted signals from Signal Generator B, at 100 kHz above the receiver's nominal frequency and unmodulated, shall be applied to the receiver through the second input of the combiner circuit.

c) An RMS voltmeter must be connected to the receiver output through a noise filter.

d) The unwanted signals are turned off, the desired signal level must be set at -53 dB, and the receiver gain is adjusted to approximately 50% of the rated speech output power.

e) The desired signal level is reduced until a SINAD ratio of 12 dB is achieved.

f) The desired signal level under these conditions is recorded as (x).

g) The frequency of the desired signal is then changed to 200 kHz from the receiver's nominal frequency. This signal forms the second unwanted signal.

h) The levels of the two unwanted signals are kept equal and increased until a SINAD ratio of 12 dB is obtained again. If necessary, the frequency of one of the two signals is slightly changed to achieve the maximum ratio, and the level is adjusted to restore the SINAD ratio to 12 dB.

i) The levels of the two signals under these conditions are recorded (y).

j) Cross-modulation suppression is the dB ratio of the unwanted signal levels (y) to the desired signal level (x).

k) These measurements must be carried out on both sides of the nominal frequency.

3.4.2.5. Measurement of blocking

a) Two input signals must be fed to the receiver through a combiner circuit. An RMS voltmeter must be connected to the receiver output through a noise filter.

b) The desired signal must be at the receiver's nominal frequency and modulated with a normal test signal (see Section 3.2.1.3), and the receiver sensitivity (see Section 2.2.1) shall be applied to the receiver inputs through the combiner circuit input.

c) If available, the receiver power control is adjusted to 50% of the rated output power (see Section 3.2.1.5).

d) The unwanted signals are not modulated and their frequencies are within ±1 MHz of the receiver's nominal frequency. The input level of the unwanted signal is adjusted until:

- The speech output power of the desired signal decreases by 3 dB; or

- The SINAD ratio at the receiver output decreases by 6 dB.

e) Blocking is the dB ratio of the unwanted signal level to the desired signal level measured at the receiver input, which decreases according to the output speech power or SINAD ratio reduction.

f) The measurements are performed at 127.5 MHz.

3.4.2.6. Measurement of receiver spurious emissions

Spurious emissions must be measured as the power level of any discrete signal at the RF input port of the receiver. The receiver output terminal is connected to a spectrum analyzer or selective voltmeter with an input impedance of 50 ohms, and the receiver is turned on.

If the splitter is not calibrated for input power, the level of any splitter component must be determined by substitution using a signal generator.

The measurements are extended across the entire frequency range from 9 kHz to 4 GHz.

3.4.2.7. Measurement of demodulation suppression

a) Two input signals must be fed to the receiver through a combiner circuit. An RMS voltmeter must be connected to the receiver output through a noise filter.

b) The desired signal must be at the receiver's nominal frequency and modulated with a normal test signal (see Section 3.2.1.3), and this signal is applied to the receiver inputs through the combiner circuit input. The signal level is set to produce a SINAD ratio of 30 dB at the receiver output using a noise filter circuit as described in ITU-T Recommendation O.41.

c) The unwanted signal at a 1 MHz offset from the receiver's nominal frequency and amplitude modulated with 400 Hz at a depth of 30% is applied to the second input of the combiner circuit.

d) The RF power level of the unwanted signal is increased until the 400 Hz subcarrier reduces the SINAD ratio of the desired signal by 20 dB.

NOTE: The source of interference must be a low-noise generator; otherwise, the required RF signals must be filtered to prevent interference.

e) The ratio between the level of this unwanted signal RF and the maximum sensitivity (as specified in Section 2.2.1) shall be completely suppressive of modulation.

f) The measurement must be repeated for a noise signal at a level below 1 MHz relative to the receiver's nominal frequency.

g) This measurement is performed at the frequency of 127.5 MHz.

3.4.2.8. Measurement of enclosure radiation

The measurements of the receiver housing radiation are specified in Section 2.3.7 of QCVN 42: 2011/BTTTT.

5. RESPONSIBILITIES OF ORGANIZATIONS AND INDIVIDUALS

Radio devices within the scope of regulation as specified in Section 1.1 must comply with the technical requirements set forth in this standard.

5. RESPONSIBILITIES OF ORGANIZATIONS AND INDIVIDUALS

Organizations and individuals related have the responsibility to implement certification and declaration of conformity for radio devices within the scope of this standard (Section 1.1) and are subject to inspection by state management agencies according to current regulations.

6. IMPLEMENTATION ORGANIZATION

6.1. The Telecommunications Administration and Provincial Departments of Information and Communications are responsible for guiding and organizing the implementation of management of radio devices within the scope of regulation as specified in Section 1.1 according to this standard.

6.2. In case there are changes, additions, or replacements to the provisions set out in this standard, they shall be implemented according to the new document/.

 

BIBLIOGRAPHY

[1] ETSI EN 300676-1 v1.5.2 (2011-03): Ground-based VHF hand-held, mobile and fixed radio transmitters, receivers and transceivers for the VHF aeronautical mobile service using amplitude modulation; Part 1: Technical characteristics and methods of measurement.