This standard specifies the technical specifications for mono, stereo, multi-channel and data FM broadcasting. This standard applies to meter wave FM broadcasting. The production, testing, acceptance and maintenance of related equipment shall comply with the technical requirements of this standard. GB/T 4311-2000 Technical Specifications for Meter Wave FM Broadcasting GB/T4311-2000 Standard Download Decompression Password: www.bzxz.net

National Standard of the People's Republic of China
GB/T4311—2000
Technical specifications for FM sound broadcasting at VHF2000-01-03 Issued
2000-08-01 Implementation
Issued by the State Administration of Quality and Technical Supervision
GB/T4311—2000
This standard is a revision of the original GB4311.1~4311.4 "FM broadcasting". This standard is based on the actual situation of the development of FM broadcasting in my country. Considering that the original standard has been used for 15 years, during which time the technical level of FM radio transmission equipment has been greatly improved, and the original technical standards are relatively backward. At the same time, the technical development and use of FM sub-channels have been put on the agenda, and corresponding standards must be standardized so that when carrying out FM sub-channel data transmission services, there are standards to follow for its spectrum, frequency deviation, modulation index, etc. The drafting group of this standard revised the original standard based on reference to International Telecommunication Union ITU-R Recommendation 450-2:1995 "Standards for Meter-wave FM Sound Broadcasting", Recommendation 300-7:1990 "Stereo/Multi-channel FM Sound Broadcasting", Recommendation 463-5:1990 "Broadcasting of Several Sound Programs or Other Signals with a Single Transmitter in FM Sound Broadcasting", Recommendation 412-7:1995 "Planning Standards for Meter-wave FM Sound Broadcasting" and advanced foreign standards. In the revision of this standard, the following aspects have been revised: 1. FM broadcasting is divided into four types: FM mono broadcasting, FM stereo broadcasting, FM multi-channel broadcasting, and FM data broadcasting; 1. Signals transmitted in the subchannel can be divided into two types: sound signal and data signal. FM broadcasting that transmits sound signals is called multi-channel broadcasting, and broadcasting that transmits data signals is called FM data broadcasting; 1. For the four FM broadcasting methods, the total frequency deviation of the transmitted signal and the limit of mutual interference are specified; 1. The maximum upper limit frequency of the subcarrier of FM data service broadcasting is specified, and there is no limit on the modulation method of the subcarrier for data signals. In the revision of the standard, the allowable deviation of antenna radiation power, polarization mode of radio waves, and allowable deviation of pilot phase in the original standard have been removed.
Subchannels are allowed to use any form of modulation, but they must be approved by the superior technical competent department. The original national standard only stipulates horizontal polarization for the polarization mode of the antenna. Considering that the polarization mode of the antenna is not stipulated in TU and foreign advanced standards, most transmitting antennas adopt circular polarization. At the same time, considering the problem of mutual interference, there is no rigid regulation for the radiation form of the antenna. If vertical polarization or circular polarization is adopted, it must be reported to the superior technical competent department for approval. From the date of implementation of this standard, the following standards are replaced: 1. GB4311.1-1984 FM broadcasting monophonic FM broadcasting stereophonic
2. GB 4311.2-1984
3. GB4311.3-1984 FM broadcasting stereophonic with additional channels 4. GB4311.4-1987 FM broadcasting dual program This standard was proposed by the former Ministry of Radio, Film and Television of the People's Republic of China. This standard is under the jurisdiction of the National Radio and Television Standardization Technical Committee. The drafting unit of this standard: Radio Station Management Bureau of the State Administration of Radio, Film and Television. The main drafters of this standard: Qian Yuelin and Tang Xuexia. I
1 Scope
National Standard of the People's Republic of China
Technical specifications for FM sound broadcasting at VHF
Technical specifications for FM sound broadcasting at VHFGB/T4311—2000
Replaces GB4311.1~4311.3—1984
GB4311.4—1987
This standard specifies the technical specifications for FM sound broadcasting at mono, stereo, multi-channel and data. This standard applies to FM sound broadcasting at VHF. The production, testing, acceptance and maintenance of related equipment shall comply with the technical requirements of this standard. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T4797.1—1984 Temperature and humidity of natural environment conditions for electrical and electronic products (eqIEC721-2-1: 1982) GB/T4797.2—1986 Altitude and air pressure, water depth and water pressure of natural environment conditions for electrical and electronic products GB/T4942.2—1993 Protection level of low-voltage electrical enclosure (eqvIEC947-1: 1988) GB9159—1988 Safety requirements for radio transmitting equipment (eqvIEC215: 1978) GB14050—1993 Type and safety technical requirements for system grounding GB/T15770—1995 Technical specifications for broadcast data system (RDS) (eqVEN50067: 1992) 3 General requirements
3.1 The frequency range of FM broadcasting is (87~108) MHz. From 87.0MHz to 107.9MHz, the radio stations are set at a frequency interval of 0.1MHz.
3.2 The modulation mode of the RF main carrier is frequency modulation, and the frequency deviation corresponding to 100% modulation is ±75kHz. 3.3 The main program refers to the sound broadcasting program of the radio station. The modulation signal of the main program is an audio signal, and the upper limit of the frequency does not exceed 15kHz. 3.4 The frequency range of the baseband signal is limited to the range from DC to 99kHz. 3.5 The pre-emphasis time constant of the main program audio signal is 50μs. 3.6 The polarization mode of the radio wave is horizontal polarization, vertical polarization or circular polarization. 3.7 Permissible deviation of carrier frequency
3.7.1 When the transmitter power is greater than 50W, the permissible deviation of the carrier frequency is ±1000Hz. 3.7.2 When the transmitter power is less than or equal to 50W, the permissible deviation of the carrier frequency is ±2000Hz. 3.7.3 For the transmitter or differential repeater that provides signals for the next level differential repeater, the permissible deviation of the carrier is ±1000Hz. 3.8 Residual wave radiation
3.8.1 When the transmitter power is greater than or equal to 25W, the residual wave radiation power should be less than 1mW and 60dB lower than the carrier power. 3.8.2 When the transmission power is less than 25W, the residual wave radiation power should be less than 25μW or 40dB lower than the carrier power. 3.8.3 When there are multiple transmitters on the same station or tower using a common antenna, their third-order intermodulation products are less than 1mW and -60dB lower than their respective RF main carriers.
3.9 General Technical Requirements for Transmitters
Approved by the State Administration of Quality and Technical Supervision on January 3, 2000, and implemented on August 1, 2000
GB/T4311—2000
3.9.1 When ordering transmitters, the impact of different working environments (including temperature, humidity and altitude) on the performance indicators of the machine should be considered. For details, please refer to GB/T4797.1 and GB/T4797.2.3.9.2 Transmitters should comply with relevant national standards in terms of both personal safety and equipment safety. For details, please refer to GB/T9159, GB/T4942.2 and GB/T14050.
3.9.3 The mechanical noise of the transmitter should be A-weighted at a distance of 1m around the transmitter and a height of 1m, and should not exceed 62dBA. 4 Mono broadcasting
4.1 Mono broadcasting refers to modulating the RF main carrier with an audio signal of 30Hz to 15kHz. The pre-emphasis time constant is 50μs, and the frequency deviation is ±75kHz when 100% modulation.
4.2 The total distortion is less than 0.5% at 100% modulation. 4.3 In the case of no emphasis and no de-emphasis, the frequency response of the audio channel (with 400Hz audio signal modulation as the reference) should be within ±0.5dB. In the case of emphasis and no de-emphasis, the frequency response of the audio channel corresponding to the standard pre-emphasis curve should be within ±0.5dB. In the case of pre-emphasis and de-emphasis, the total frequency characteristic does not exceed ±1dB. 4.4 When the audio signal frequency is 1kHz with the maximum modulation degree, the signal-to-noise ratio (with 1kHz as the reference, pre-emphasis) is greater than 60dB. 5 Stereo broadcasting
5.1 Stereo broadcasting adopts the pilot system. The modulation signal of the RF main carrier is a stereo composite signal. 5.1.1 The stereo composite signal is composed of the following signals: Signal M: It is composed of half of the sum of the left stereo signal L and the right stereo signal R. Signal M is pre-emphasized in the same way as the mono signal, which is the 30Hz to 15kHz part of the baseband signal; Signal S: It is composed of half of the difference between the left stereo signal L and the right stereo signal R. Signal S is pre-emphasized in the same way as signal M. The pre-emphasized S signal performs double-sideband amplitude modulation of the double frequency of the pilot signal with suppressed carrier, which is the 23kHz to 53kHz part of the baseband signal;
Pilot signal: The pilot signal frequency is 19kHz. When the pilot signal intersects the time axis, the 38kHz signal intersects the time axis at a positive slope at the same time. The baseband of the stereo composite signal is shown in Figure 1. 100%
Signal M
15k t9k 23k
Signal s
Figure 1 Baseband diagram of stereo composite signal
5.1.2 Modulation degree of stereo composite signal
Signal M: Maximum is 90% of the modulation degree of ±75kHz (the amplitude of the left signal L and the right signal R are equal and in phase); Signal S: Maximum is 90% of the modulation degree of ±75kHz (the amplitude of the left signal L and the right signal R are equal but in opposite phase); 19kHz pilot: 8%~10% of ±75kHz. 5.2 Technical indicators of stereo broadcasting
5.2.1 The technical indicators of the left and right channels of stereo broadcasting are the same as those of mono. 5.2.2 The allowable frequency deviation of the pilot signal is less than ±1Hz. 5.2.3 The modulation degree of the 38kHz residual component of the modulated S signal on the RF main carrier is less than 1%. 5.2.4 The separation between the left and right signals is greater than 40dB at 100% modulation. 2
GB/T4311—2000
5.2.5 The level difference between the left and right signals is less than 1dB at 55% modulation (of which the pilot frequency is 10%), regardless of whether it is emphasized or not. 5.3 In order to improve the coverage of stereo broadcasting, the FMX system is allowed to add an orthogonal subcarrier amplitude modulation channel that suppresses the subcarrier using compression and expansion technology. The subcarrier frequency is the original 38kHz, but the phase difference with the original subcarrier is 90°. 6 Multi-channel broadcasting
Multi-channel broadcasting refers to adding a broadcast program (supplementary program) that is frequency modulated on a 67kHz subcarrier in addition to the mono or stereo broadcasting (main program).
6.1 FM Dual Program
FM dual program refers to the modulation of additional program signals on the 67kHz subcarrier during mono (main program) broadcasting. 6.1.1 The maximum modulation frequency deviation of the RF main carrier is ±75kHz. Among them, the maximum frequency deviation of the main program modulating the RF main carrier accounts for 70%, and the frequency deviation of the subcarrier modulating the RF main carrier accounts for 30%. 6.1.2 The maximum frequency of the additional program audio signal is 10kHz, the pre-emphasis time constant is 75μs, and the compression ratio is 2:1. 6.1.3 The additional program audio signal uses frequency modulation to modulate the subcarrier, and its maximum frequency deviation is ±8kHz. After the additional program modulates the subcarrier, it occupies the 49kHz to 85kHz segment of the baseband. As shown in Figure 2. 100%~
6.1.4 Technical requirements
Main channel signal
Identification or modification signal
Figure 2 FM dual program baseband diagram
85k (Hz)
Except that the signal-to-noise ratio is set to be greater than or equal to 52dB, the technical indicators of the main channel are the same as those of the mono channel. Technical requirements for additional program channels:
The total deviation of the subcarrier frequency is less than 100Hz;
-The total distortion of the audio from 50Hz to 10kHz is less than or equal to 2% for the subcarrier ±8kHz frequency deviation modulation and for the main carrier 30% modulation
-The total frequency response (with compression and expansion and de-emphasis) is within ±2dB;-The signal-to-noise ratio corresponding to the subcarrier 8kHz frequency deviation is greater than or equal to 60dB in the case of compression and expansion;-The crosstalk between the main channel and the additional program channel (with de-emphasis, using a frequency selector to measure the fundamental wave) is better than -60dB. 6.2 Stereo with additional programs
Stereo with additional programs refers to the addition of an additional program modulated on a 67kHz or 76kHz subcarrier during stereo broadcasting.
6.2.1 The modulation frequency deviation of the stereo composite signal to the RF main carrier is 90% of the maximum frequency deviation, and the modulation frequency deviation of the additional program subcarrier to the RF main carrier is 10% of the maximum frequency deviation.
6.2.2 The upper frequency limit of the additional program audio signal is 6kHz, and the pre-emphasis time constant is 50μs. Companding technology can be used with a compression ratio of 2:1.
6.2.3 The additional program signal uses frequency modulation on the modulated subcarrier, and its maximum modulation frequency deviation is ±4kHz. The frequency deviation of the additional subcarrier to the RF main carrier is 10% of the maximum frequency deviation (±7.5kHz). For a 67kHz subcarrier, the additional program signal occupies the 61kHz to 73kHz segment of the baseband signal after modulation, as shown in Figure 3. For a 76kHz subcarrier, the additional program signal occupies the 70kHz to 82kHz segment of the baseband signal after modulation, as shown in Figure 4. 3
6.2.4 Technical requirements
Multiple M
GB/T4311—2000
15k19k23k
The attached signal
Stereo additional program baseband diagram
Add section II carrier signal
15k19k23k
Figure 4 Stereo additional program baseband diagram
82k (Hz)
When stereo broadcasting with additional programs, the technical index requirements for the main channel are the same as Section 5.2 "Technical requirements for stereo broadcasting". Technical requirements for additional program channels:
- The total deviation of the subcarrier frequency is less than 100Hz; - The total distortion of the additional program within the frequency range of 80Hz to 6kHz is less than or equal to 3% for the subcarrier ±4kHz frequency deviation modulation and the main carrier 10% modulation
The total frequency response (including compression and de-emphasis) is within ±2dB; - The signal-to-noise ratio (pre-emphasis, including compression and expansion) is greater than 60dB. - The crosstalk of the stereo left and right channels to the additional program channel, and the crosstalk of the additional program channel to the stereo left and right channels, regardless of whether the additional program channel is compressed or not, should be better than -65dB. 7 FM data broadcasting
FM data broadcasting refers to the use of the spare spectrum of the FM baseband to broadcast specific data while performing FM mono broadcasting and FM stereo broadcasting.
These data can be some kind of identification information, data or image information, collectively referred to as sub-channel information. The channel used to transmit this information is called a sub-channel.
To improve the utilization of the subchannel, data compression and packaging are allowed, and a self-contained transceiver protocol is allowed. Subchannel information should usually be modulated twice on the subcarrier. The number of subcarriers can be one, or multiple subcarriers can be used according to the situation. Broadcasting does not require the bit rate, bit error rate, and bit error protection method for transmitting information using the subchannel. It is determined according to the situation, the occasion of use, and the service object. Equipment that complies with GB/T15770 can be used directly. 7.1 Modulation methodbzxZ.net
For transmitting subchannel information, any form of modulation method can be used. 7.2 Subcarrier baseband
7.2.1 For mono program broadcasting, the effective sideband of the data broadcast subcarrier must be limited to the range of 20kHz to 99kHz. 7.2.2 For stereo program broadcasting, the effective sideband of the data broadcast subcarrier must be limited to the range of 53kHz to 99kHz. 7.2.3 During the period when no broadcast program is transmitted, the effective sideband of the data broadcast subcarrier must be limited to the range of 20kHz to 99kHz. 4
7.3 Modulation distribution
GB/T4311—2000
7.3.1 When data broadcasting is carried out, the total modulation degree of the RF main carrier is allowed to be 110% of ±75kHz, that is, the frequency deviation is 82.5kHz. 7.3.2 For mono programs, the sum of the carrier modulation degrees of all subcarriers shall not exceed 30% relative to the frequency deviation of ±75kHz, and shall not exceed 20% for frequency deviations above ±75kHz. 7.3.3 For stereo programs, the sum of the carrier modulation degrees of all subcarriers shall not exceed 10% relative to the frequency deviation of ±75kHz, and shall not exceed 20% for frequency deviations above ±75kHz. 7.3.4 During the period when no broadcast programs are transmitted, the sum of the carrier modulation degrees of all subcarriers shall not exceed 30%. 7.4 Subcarrier frequency
According to the usage of the main program broadcast, the subcarrier frequency can be set and selected accordingly, but its maximum frequency shall not exceed 76kHz, and the allowable deviation of the subcarrier frequency shall not exceed 100Hz. 7.5 Interference of the subchannel to the main channel
In order to ensure the normal broadcast of the main channel program, the spectrum of the subchannel has the following requirements: 7.5.1 The spectrum components of the sub-channel spectrum falling within the main channel must be less than 60dB relative to the power sum of the sub-channel spectrum components when the modulation is 100%.
7.5.2 The sub-channel spectrum at 100kHz in the baseband must be less than 60dB of the total power of the baseband signal when the carrier is 100% modulated. 7.5.3 The technical indicators after adding the sub-channel are compared with those without the sub-channel. The separation decreases by less than 0.5dB, the distortion deteriorates by less than 0.1%, and the signal-to-noise ratio decreases by no more than 0.5dB.
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