Some standard content:
Military Standard of the Electronic Industry of the People's Republic of China FL5820
SJ20043—92
Measurement Method for Short Wave Single Sideband Radio Station
Moethods of Measurement for Short Wave Single Sideband Set
Published on 1992-02-01
China Electronics Industry Corporation
Implemented on 1992-05-01
Military Standard of the Electronic Industry of the People's Republic of China Measurement Method for Short Wave Single Sideband Radio Station
Moethods of Measurement for Short Wave Single Sideband set
1 Subject content and scope of application
This standard specifies the electrical performance measurement method of shortwave single-sideband radio stations without complete antennas. SJ20043-92
This standard is applicable to shortwave single-sideband (including independent sideband) radio stations without complete antennas that receive and transmit voice frequency and other types of signals, and whose audio bandwidth does not exceed 10kHz, full carrier (H3E), reduced amplitude carrier (R3E) and suppressed carrier (J3E).
This standard only provides the measurement method of electrical performance and the provisions of relevant conditions. The measurement items and performance indicators are specified by the product specifications.
For special radio stations, the definitions and measurement methods of electrical performance items that are not specified in this standard shall be determined by the supply and demand parties through consultation.
2 Reference standards
GB6933-86 Shortwave single sideband transmitter electrical performance measurement method GB6934-86
Shortwave single sideband receiver electrical performance measurement method 3 Terminology
In addition to Chapter 1 (Special terms and definitions for measurement) of GB6933 and GB6934, which are applicable to this standard, the following special terms are introduced according to the needs of this standard.
3.1 Radio station
radio station
The radio station described in this standard refers to a combination of a transmitter and a receiver, and includes the auxiliary equipment necessary for radio communication work in one place. 3.2 Squelch
squelch
The process in which the device in the receiver automatically suppresses the response (usually the sound response) when the excitation or signal-to-noise ratio is lower than a predetermined value.
3.3 Automatic tuning
automatic tuning
When a radio station is receiving or transmitting, the receiving part or the transmitting part can automatically adjust a group of coherent circuits to make them basically correctly tuned.
China Electronics Industry Corporation Issued on February 1, 1992 Implemented on May 1, 1992
4. Measurement conditions
4.1 Measurement instrument conditions
SJ20043—92
The accuracy of the measuring instrument should ensure the accuracy requirements of the measured indicators. For example, the frequency accuracy of the instrument and equipment related to the measurement of frequency error must be several orders of magnitude higher.
The selection of the measuring instrument should meet the characteristics of the measured performance. For example, the indicated values of the audio voltmeter and distortion coefficient meter used to measure the standard signal should be able to reflect the effective value of non-sinusoidal waves. For individual projects, the measuring instrument should be appropriately selected to prevent the instrument from introducing side effects. For example, when measuring out-of-band intermodulation, intermodulation products between signal generators should be avoided.
The main performance specifications of these general measuring instruments are shown in Appendix B (Supplement) of GB6933 and Appendix A (Supplement) of GB6934.
4.2 Standard test conditions
4.2.1 Overview
Unless otherwise specified, the measurements of the series of electrical performance of the radio shall be carried out under the standard test conditions specified in Articles 4.2.2 and 4.2.3.
4.2.2 Standard power supply conditions
4.2.2.1 Overview
The voltage and frequency of the power supply shall be measured at the power input terminal when the radio is working. If the radio is connected to non-detachable wires and cables, it can be measured at the power input plug, but the type, cross-sectional shape and length of the wires and cables shall be recorded. The standard power supply is divided into DC power supply and AC power supply. 4.2.2.2. Standard test voltage of DC power supply The total DC power supply standard test voltage is measured according to the total nominal voltage, and its error shall be less than ±2%, and the ripple shall be less than 2%. 4.2.2.3 Standard test voltage and frequency of AC power supply Unless otherwise specified, the standard test voltage is 220V, and its error should be less than ±2%. The standard test frequency is 50Hz, and its error should be less than ±2%. The harmonic distortion coefficient should be less than 5%. 4.2.3 Standard atmospheric conditions
Measurements under standard atmospheric conditions should be carried out according to the conditions specified in Article 4.2.3.1. If necessary, the measurement results can be corrected by calculation for the conditions specified in Article 4.2.3.3. If this correction is not possible, the measurement should be carried out according to a set of arbitration conditions specified in Article 4.2.3.2.
4.2.3.1 Normal test atmospheric conditions
The temperature, humidity and air pressure ranges of normal test atmospheric conditions are specified in Table 1. Table 1 Normal test atmospheric conditions
15~35℃
Relative humidity
45%75%
86106kPa
In a series of measurements on a given device, the temperature and relative humidity should be roughly stable. Note: When the conditions specified in Table 1 cannot be used for measurement, the reasons and the actual atmospheric conditions should be attached to the test report. 4.2.3.2 Standard atmospheric conditions for arbitration tests If the measured parameters are related to temperature, humidity and air pressure, and the dependence between them is unclear, the measurements can be carried out under a set of conditions in Table 2 with the agreement of both the supplier and the buyer. 2
SJ20043-92
Table 2 Standard atmospheric conditions for arbitration test
Relative humidity
86~106
86~106
86~106
It is best to measure at 20℃. With the agreement of the supply and demand parties, the measurement may not be carried out at 20℃. In this case, the two parties shall agree on a suitable limit for a specific parameter. Note: The actual values of temperature, humidity and air pressure during measurement shall be written in the test report. 4.2.3.3 Reference standard atmospheric conditions
The temperature and air pressure values of the reference standard atmospheric conditions are specified in Table 3. Table 3 Reference standard atmospheric conditions
+20℃
The reference standard atmospheric conditions do not give relative humidity because it is generally impossible to calculate the influence of relative humidity on the measured parameters. Note:
4.3 Measurement workplace conditions
The measurement workplace should be clean and should not contain gas, salt mist or strong sunlight radiation that may damage the equipment. Measures should be taken to isolate industrial interference, spark interference and atmospheric interference. Obvious mechanical vibration and impact should be avoided. Measurement items
The electrical performance measurement of shortwave single-sideband radio stations usually consists of three parts: the receiving/transmitting common part, the receiving part and the transmitting part (including the antenna tuner). Tables 4, 5 and 6 give the measurement items of the above three parts respectively. These items are the main electrical performance measurement items of shortwave single-sideband radio stations, and not all items must be included in every radio station. The purpose of this standard is to standardize the definition of the electrical performance of shortwave single-sideband radio stations and their measurement methods, so as to compare the measurement results of different radio stations and different measurers.
Table 4 Measurement items for receiving/transmitting common parts Sequence
Electrical performance name
Maximum frequency error
Frequency stability
Input power (power consumption)
Input power (power consumption) should be measured when the radio is transmitting and receiving. Corresponding measurement method clause number
Article 3.15 of GB6933
Article 3.16 of GB6933
Article 3.24 items
SJ20043—92
Measurement items for receiving part
Function name
Reference sensitivity
Audio response
Harmonic distortion coefficient
Relative audio intermodulation
Adjacent signal selectivity
Reciprocal mixing
Out-of-band intermodulation
Conducted parasitic distortion
Combined tone
Automatic gain control Control characteristics
Intermediate frequency suppression ratio
Image frequency suppression ratio
Spurious frequency suppression ratio
Large signal signal-to-noise ratio
Cross modulation
Squelch opening level and lockout level
Squelch opening delay and lockout delay
Pulse noise tolerance
Transmit/receive conversion time
Some other measurement items of the receiving part, the measurement methods of which are shown in GB6934. Table 6
Measurement items of transmitting part
Electrical performance name
Average power
Peak envelope power
Relative intermodulation product level (intermodulation distortion)Sideband suppression
Out-of-band power
Carrier suppression
Channel input level
Audio frequency modulation characteristics (Channel frequency response)Audio harmonic distortion coefficient
Hum level
In-band side wave
False signalNarrow-band RF component (residual wave radiation)Phase jitter
Receive/transmit conversion time
Tuning time
Tuning accuracy
RF efficiency (antenna tuner)
Some other measurement items, the measurement methods of which are shown in GB6933. Others of the emission part
Corresponding measurement method clause number
3.1 in GB6934
3.3 in GB6934
3.5 in GB6934
3.6 in GB6934
3.7 in GB6934
3.9 in GB6934
3.10 in GB6934
GB693 4 Article 3.11
Article 3.14 in GB6934
Article 3.15 in GB6934
Article 3.16 in GB6934
Corresponding measurement method clause number
Article 3.1 in GB6933
Article 3.2 in GB6933
Article 3.3 in GB6933
Article 3.4 in GB6933
Article 3.5 of GB933
Article 3.6 of GB6933
Article 3.8 of GB6933
Article 3.10 of GB6933
Article 3.12 of GB6933
Article 3.17 of GB6933
Article 3.18 of GB6933
Article 3.19 of GB6933
Article 3.22 of GB6933||tt| |RF signal
Generator G2
Radio signal
Generator G
Matching network or hybrid
Matching network
RF signal
Generator G,
SJ20043—92
Test station
Audio load
①The input impedance of the four parallel instruments connected to the output of the radio station 2. Must meet: Z, >> R. Note:
Figure 1 is the same as Figure 4 in GB6934. ③The instruments in the dotted box are set as needed. Figure 1 Connection diagram for measuring the characteristics of the receiving part of a radio station Figure 6 Definition and measurement method of the electrical performance of the receiving part Audio frequency meter or
Counting frequency meter
Distortion coefficient meter
Audio voltmeter
Spectrum analyzer or
Audio frequency selective voltmeter
For radio stations whose automatic gain control can be disconnected, in addition to measuring the large signal signal-to-noise ratio (or large signal signal-to-noise ratio), automatic gain control characteristics and volume control of the receiving part of the radio station, when measuring other items specified in this standard, the automatic gain control switch of the radio station should be set to "off", and all gain controls except the intermediate amplifier gain (or RF gain) should be adjusted to the maximum position. For radio stations whose automatic gain control cannot be disconnected, the relevant items should be measured according to the actual working status of the radio station. 6.1 Intermediate Frequency Rejection Ratio
6.1.1 Definition
The ratio of the unwanted signal input level to the reference sensitivity is the intermediate frequency suppression ratio, expressed in decibels. In radios with multiple frequency conversions, there are first intermediate frequency suppression ratios and second intermediate frequency suppression ratios. 5
6.1.2 Measurement Method
SJ20043—92
a. Connect the equipment according to Figure 1, and connect the additional RF signal generator G (unwanted signal source) to the C terminal of the hybrid matching network.
b. When there is no unwanted signal, measure the reference sensitivity according to Article 3.1.2 of GB6934, and record the input signal level at this time, expressed in microvolts or decibels (microvolts). c. Add an unwanted, unmodulated high-level signal [e.g., 100 dB (μV)] to the C terminal of the hybrid matching network. d. Adjust the frequency of G to the intermediate frequency of the radio receiving part, and adjust the output level of G so that the radio audio output is equal to the output level in step b. Record the input signal level of the radio at this time, expressed in microvolts or decibels (microvolts). e. The ratio of the unwanted signal level recorded in step d to the reference sensitivity is the intermediate frequency rejection ratio, expressed in decibels. 6.2 Image rejection ratio
6.2.1: Definition
An unwanted signal input level with a frequency equal to the image frequency of the radio receiving part makes the radio output level equal to the output level of the reference sensitivity. The ratio of this unwanted signal input level to the reference sensitivity is the image rejection ratio, expressed in decibels.
6.2.2 Measurement method
a. Connect the equipment according to Figure 1, and connect the additional RF signal generator G: (unwanted signal source) to the C terminal of the hybrid matching network.
When there is no useless signal, measure the reference sensitivity according to 3.1.2 of GB6934, and record the input signal b.
level at this time, expressed in microvolts or decibels (microvolts). c. Add a useless, unmodulated high-level signal [such as: 100dB (μV)] to the C end of the hybrid matching network. d. Adjust the frequency of G, to the image frequency of the radio receiving part, and adjust the output level of G: so that the audio output of the receiver is equal to the output level in step b, and record the input signal level of the radio at this time, expressed in microvolts or decibels (microvolts). e. The ratio of the useless signal level recorded in step d to the reference sensitivity is the image frequency rejection ratio, expressed in decibels. 6.3 Parasitic frequency suppression ratio
6.3.1 Definition
Except for the intermediate frequency and the image frequency, all the additional reception caused by the frequency conversion technology and the frequency synthesis technology is generally called parasitic frequency interference: an unwanted signal input level makes the output level of the parasitic frequency interference of the radio receiving part equal to the output level of the reference sensitivity. The ratio of this unwanted signal input level to the reference sensitivity is the parasitic frequency suppression ratio, expressed in decibels. 6.3.2 Measurement method
a. Connect the equipment according to Figure 1, and connect the additional RF signal generator G (unwanted signal source) to the C terminal of the hybrid matching network.
b. When there is no unwanted signal, measure the reference sensitivity according to Article 3.1.2 of GB6934, and record the input signal level at this time, expressed in microvolts or decibels (microvolts). c. Add an unwanted, unmodulated high-level signal [such as: 100dB (μV)] to the C terminal of the hybrid matching network. d. Within the specified measurement frequency range, change the frequency of the unwanted signal to search for spurious frequency response. When the audio output of the unwanted signal is found, carefully adjust the frequency of the unwanted signal to maximize the audio output. e. At each spurious frequency, change the unwanted signal input level so that the audio output of the radio is equal to the output level in step b, and record the input signal level of the radio at this time, expressed in microvolts or decibels (microvolts). f. The ratio of the unwanted signal level recorded in step e to the reference sensitivity is the spurious frequency suppression ratio, expressed in decibels. 6.4 Large Signal Signal-to-Noise Ratio
6.4.1 Definition
SJ20043--92
The output signal-to-noise ratio when the input signal of the receiving part of the radio is the standard input signal level is called the large signal signal-to-noise ratio, expressed in decibels.
6.4.2 Measurement method
6.4.2.1 Measurement method when the input signal is full carrier (H3E) or reduced carrier (R3E) a. Connect the equipment as shown in Figure 1.
b. Apply a standard input signal level to the input terminal of the radio. c.
The automatic gain control of the receiving part of the radio is set to "connected", the automatic gain control time constant is set to the maximum position (such as 10s), the intermediate amplifier gain or the RF gain is set to the maximum position, and the radio with volume control adjusts the volume control of the receiving part to obtain the reference output level, and records the output level at this time. d Turn off the input sideband signal and record the noise level of the audio voltmeter at this time. e The ratio of the output signal level recorded in step C to the noise level recorded in step d is the large signal signal-to-noise ratio, expressed in decibels.
6.4.2.2 Measurement method when the input signal is suppressed carrier (J3E) a. Connect the equipment according to Figure 1.
Apply a standard input signal level to the input terminal of the radio. The automatic gain control of the receiving part of the radio is set to "connected", the automatic gain control time constant is set to the maximum position (such as c.
10s), the intermediate amplifier gain or the RF gain is set to the maximum position, and the radio with volume control adjusts the volume control of the receiving part to obtain the reference output level, and records the output level at this time. d. Turn off the input signal and immediately change the range control knob of the audio voltmeter to increase the sensitivity of the audio voltmeter (for example, set it to the 10mV range).
e. Observe that the pointer of the audio voltmeter falls due to inertia and then rises to the first stable value, and record the noise level at this time.
f. The ratio of the output signal level recorded in step c to the noise level recorded in step e is the large signal signal-to-noise ratio, expressed in decibels.
6.5 Cross-modulation
6.5.1 Definition
In the receiving part of the radio, the amplitude of the useful signal is modulated by the modulated unwanted signal is called cross-modulation. 6.5.2 Measurement method
Connect the equipment according to Figure 1 and connect the additional RF signal generator G (unwanted signal source) to the ca of the mixing and matching network.
When there is no unwanted signal, add a standard input signal to the input of the radio. Adjust the volume control of the receiving part of the radio to obtain the reference output level. c.
Add an unwanted signal with a modulation frequency of 400Hz and a modulation degree of 30% to the C terminal of the hybrid matching network, and adjust the unwanted input signal frequency to a specified value (for example, ±30kHz) away from the standard input signal frequency. e. Increase the level of the unwanted input signal until the signal-to-noise ratio or signal-to-noise ratio at the output of the radio drops to 20dB. Record the unwanted input signal level at this time, which is the cross modulation, expressed in decibels (microvolts). 6.6 Squelch opening level and lockout level
6.6.1 Definition
The modulated input signal level when the squelch is opened and locked is called the squelch opening level and lockout level (Figure 2). If the radio 2
SJ20043—92
has an adjustable squelch control, these level values will change with different control adjustments. 6.6.2 Measurement method for radios with adjustable squelch control Connect the equipment according to Figure 1.
(Time-frequency output level
Squelch frequency signal
Squelch lockout level
Squelch opening level
Note: The RF input signal level in the figure is relative and is for illustration only. Figure 2 Squelch opening level and lockout level
No squelch frequency signal
No squelch noise
Benchmark sensitivity
Radio input signal level
Add a test signal to the input end of the radio. The modulation characteristics of the signal should be suitable for the specific squelch circuit of the radio. Its level is 1mV (except for special circumstances).
c. Make the radio work at the reference output level. d. Reduce the input signal level to the smallest possible value. Adjust the squelch control until the squelch is The squelch is turned on. If the squelch is not turned on, adjust the squelch control to the minimum signal position required for reception without squelch, and continue with step h. e. Adjust the squelch control until the squelch is just locked (that is, the radio speaker goes from having sound to the position where there is just no sound). f. Increase the input signal level until the squelch is just opened (that is, the radio speaker goes from no sound to the position where there is just continuous sound).
g: Reduce the input signal level to the minimum value again and observe whether the squelch is locked again. If the squelch is not locked, readjust the squelch control until the squelch is just locked. h. Increase the input signal level until the squelch is just opened. The signal level at this time is recorded as the minimum squelch opening level, expressed in microvolts or decibels (microvolts). i. Reduce the input signal level until the squelch is just opened. j. Adjust the squelch control to the maximum signal position required for squelch-free reception. Adjust the input signal level until the squelch is just opened, and record the signal level at this time as the maximum squelch opening level, expressed in microvolts or decibels (microvolts). k. Lower the input signal level until the squelch is just locked, and record the signal level at this time as the maximum squelch locking level, expressed in microvolts or decibels (microvolts). 6.6.3 The measurement method for radio stations with preset squelch control is to measure according to steps a, b, c, d, h and i in Article 6.6.2. The signal levels measured in steps h and i are the squelch opening level and locking level.
SJ2 0043—92
Note: For other types of squelch (such as pilot type, emergency type, etc.), the measurement method shall be determined by the supply and demand parties through negotiation. 6.7 Squelch opening delay and lockout delay
6.7.1 Definition
The time interval between the instant when the modulated RF input signal level reaches the specified increase or decrease amount and the instant when the voltage across the audio load is equal to 50% of the steady-state value without squelch control is called squelch opening delay and lockout delay. 6.7.2 Measurement method
a. Connect the equipment according to Figure 1, connect the calibrated horizontal scanning oscilloscope in parallel with the audio load, and connect an electronically controlled single-stage step attenuator with an attenuation of not less than 30dB between the input signal source and the radio station to be tested. Note: The switching time of the attenuator should be shorter than the expected squelch opening and locking time. b. The radio operates without input signal. If the radio has an adjustable squelch control, adjust the squelch control so that the squelch is just locked (see step g in 6.6.2). c. Apply a test signal to the input of the radio. The modulation characteristics of the signal should be suitable for the specific squelch circuit of the radio. Its level is 1mV (except in special cases). The radio operates at the reference output level and records the level value on the oscilloscope. d. Set the 30dB single-stage step attenuator to the maximum attenuation value and adjust the input signal level of the radio until it is about 6dB lower than the minimum squelch lock level.
e. The sync pulse of the horizontal scan scale of the oscilloscope is driven by the attenuator start signal. f. Change the step attenuator from maximum attenuation to minimum attenuation, measure and record the time from the time of changing the attenuation to the time when the voltage across the audio load increases to more than 50% of the voltage value recorded in step c. The time interval between the two is the squelch opening delay.
g. Change the step attenuator from minimum attenuation to maximum attenuation, measure and record the time interval from the time of changing the attenuation to the time when the voltage across the audio load drops to 50%. This time interval is the squelch lock delay. Note: A dual-trace memory oscilloscope can also be used for display: the RF signal that triggers the scan is displayed on one scan line: the audio signal is displayed on the other scan line.
6.8 Impulse noise tolerance
6.8.1 Overview
Impulse noise will reduce the sensitivity performance of the radio receiving part. In order to maintain the specified signal-to-noise ratio, the input signal level needs to be increased. The impulse noise response characteristics of the radio receiving part will change with the spectral amplitude of the noise and the repetition rate of the noise pulse [see Appendix A (Supplement)].
6.8.2 Definition
The ability of the radio receiving part to prevent the output response of the receiving part from being reduced due to impulse noise is called impulse noise tolerance. Usually, the impulse noise tolerance is expressed as the ratio of the median level of the impulse noise spectrum amplitude to the reference sensitivity. The median level of the impulse noise spectrum amplitude refers to the impulse noise spectrum amplitude that keeps the standard signal-to-noise ratio at the output of the receiving part when the input signal level of the radio receiving part is 3 dB higher than the reference sensitivity. 6.8.3 Measurement method
a. Calibrate the random pulse generator according to Chapter A3 in Appendix A (Supplement), and record the minimum attenuation median spectrum amplitude S and the minimum attenuation M, and then increase the attenuation to a high value. b. Connect the equipment according to Figure 1 and connect the random pulse generator to the C terminal of the hybrid matching network. c. When there is no impulse noise signal, add the standard input signal to the hybrid matching network according to Article 2.3.3 of GB6934, and reduce its level to obtain the reference sensitivity at the input of the radio receiving part. —9-
SJ20043--92
d. Increase the useful signal input level by 3 dB. Adjust the random pulse generator to the following position; e.
The frequency is 100kHz lower than the standard input frequency; the average pulse repetition rate is 100 pulses/s; the pulse duration is 0.2uμs;
The standard deviation of the amplitude is 6dB
The cut-off frequency of the low-pass filter is 10Hz; the spectrum amplitude is the minimum value.
Note: The adjustment of the random pulse generator simulates the noise generated by urban vehicles radiated to the antenna of a nearby land mobile station. The above adjustment of the random pulse generator is not applicable to other environments. f. Adjust the attenuation of the random pulse generator until the standard signal-to-noise ratio or standard signal-to-noise ratio is obtained at the output end of the radio receiving part, and record the attenuation A at this time, expressed in decibels. 6.8.4 Result expressionwwW.bzxz.Net
a. Impulse noise tolerance is:
S-A+MBE
Where: S—the minimum attenuation median spectrum amplitude recorded in step a of 6.8.3; A—the attenuation recorded in step f of 6.8.3; M——the minimum attenuation recorded in step a of 6.8.3; B—the loss of the hybrid matching network, dB; E
—the reference sensitivity, dB (μV).
Record the impulse noise tolerance, standard input signal frequency, reference sensitivity and the adjustment position of the random pulse generator. Radio station under test
Audio signal
Generator
6.9 Transmit/receive conversion time
6.9.1 Definition
RF attenuator
The time required for a radio station to switch from the transmitting state to the receiving state is called the transmit/receive conversion time. 6.9.2 Measurement method
a. Connect the equipment according to Figure 3.
Test load
Transmit/receive keying
Digital
Storage oscilloscope
b. The audio signal generator outputs a 0dBm, 1kHz signal and adds it to the input of the radio. The radio operates in the sideband voice-10
operating type, and the operating frequency is specified by the product specification. SJ20043—92
C. Press the radio button, and the transmit/receive keying signal triggers the radio and oscilloscope at the same time. A stable RF envelope appears on the oscilloscope. The radio is turned on, and the time required from the trigger moment to the RF envelope dropping to 10% of the stable value is measured, which is the transmit/receive conversion time, expressed in milliseconds.
7 Transmitting part electrical performance definition and measurement method 7.1 Transmit/receive conversion time
, 7.1.1 Definition
The time required for the radio to change from the receiving state to the transmitting state is called the transmit/receive conversion time. 7.1.2 Measurement method
a. Connect the equipment according to Figure 3.
b. The audio signal generator outputs a 0dBm, 1kHz signal and applies it to the input of the radio. The radio works in the sideband voice working type, and the working frequency is specified by the product specification. Press the C radio button and measure the time required from the trigger moment to the RF envelope rising to 90% of the stable value displayed on the oscilloscope. This is the transmit/receive conversion time, expressed in milliseconds. 7.2 Sidetone
7.2.1 Definition
The signal output from the transmitting part (or exciter part) of the radio is combined with part of the signal to form an audio output to the receiving part as a monitoring signal. This signal is called sidetone. 7.2.2 Measurement method
Radio station to be tested
Audio voltmeter
Connect the equipment as shown in Figure 4.
Test load
The radio station operates in the "sideband alarm" working type, and the operating frequency is set to the frequency specified in the product specification. b.
Make the radio tune normally and the transmitting part outputs the rated power. c.
Press the d button and use the audio voltmeter to check whether the side tone can be adjusted within the specified voltage range. 7.3 Tuning time
7.3.1 Definition
In a radio station with automatic tuning, the time required for the antenna tuner to automatically tune the transmitting part of the radio station and the antenna from a mismatched state to a matched state is called the tuning time. 7.3.2 Measurement method
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.