Project design

3.1.1 PA system engineering design shall meet the reasonable needs of users on a safe, environmental friendly, energy-saving and resource-saving basis.
3.1.2 PAE shall pass the China Compulsory Certification (CCC) in accordance with the requirements of relevant national provisions.
3.1.3 PA shall be a mono broadcast.

3.1.4 PAS shall be designed based on purposes and class requirements.

3.1.5 One PAS may serve multiple broadcast purposes. The class of each broadcast purpose may be set separately.
3.1.6 PAS in a flammable and explosive area must comply with the requirements of current national standards GB 3836.1, Electrical apparatus for explosive gas atmospheres-- Part 1: General requirement and GB 3836.2, Electrical apparatus for explosive gas atmospheres-- Part 2: Flameproof enclosure "d".
3.1.7 PA system engineering design shall include the following documents:

1 system structure diagrams and related descriptive documents,

2 routing of broadcast transmission lines and plans of loudspeakers distribution,

3 configuration diagrams of the control center and related equipment,

4 equipment list.

3.2 Ensured functions

3.2.1 PAS shall be able to release real-time speech broadcast and one microphone with the highest priority shall be available.
3.2.2 In the case that multiple signal sources are being broadcast to the same zone, the signal with higher priority shall be able to override the signal with lower priority automatically.
3.2.3 In addition to the requirements stipulated in article 3.2.1 of this code, the ENF of business announcement system shall also be in accordance with those specified in Table 3.2.3.
Table 3.2.3 Other ENFs of business announcement system
Class Other ENFs



Class 1 ● programming management
● automatic running (allowing manual intervention) and the timing error shall not be more than 10 s
● zoning with matrix mode
● zoning override
● airing priority ranking
● automatic switch between master/standby power amplifiers
● supporting call stations
● supporting remote control and monitor
 

Class 2 ● automatic running (allowing manual intervention)
● zone management
● override
● fault warning for power amplifier
Class 3 ——

3.2.4 In addition to the requirements stipulated in article 3.2.1 of this code, the ENFs of background broadcast system shall also be in accordance with those specified in Table 3.2.4.
Table 3.2.4 Other ENFs of background broadcast system
Class Other ENFs


Class 1 ● programming management
● automatic running (allowing manual intervention)
● tone adjustment
● zoning with matrix mode
● zoning override
● airing priority ranking
● supporting remote control and monitor

Class 2 ● automatic running (allowing manual intervention)
● tone adjustment
● zone management
● override

Class 3
——

3.2.5 In addition to the requirements stipulated in article 3.2.1 of this code, the ENFs of emergency broadcast system shall also be accordance with the following requirements.
1 As to a PAS serving multiple purposes, emergency broadcast shall be with the highest priority. In case of being triggered manually or automatically, PAS shall be able to broadcast alarm signals (including alarm sirens), alarm voice files or real-time command voice to the relevant zone(s) within 10 s.
2 Based on the environmental noise on site, the SNR of emergency broadcast shall be no less than 12 dB.
3 Emergency broadcast system equipment shall be in DFS state or be with the functions of scheduled self-test and automatic fault warning.
4 Emergency broadcast system shall be equipped with a standby power supply. The switching time between the primary power supply and standby power supply shall not be more than 1
s. The standby power supply shall be able to sustain emergency broadcast for over 20 min.  If battery is used as the standby power supply, the system shall be equipped with automatic recharging device.
5 The volume of emergency broadcast shall be able to reach the level no less than the ENSPL automatically.
6 In the case that it is necessary to release emergency broadcast manually, one touch ready shall be available.
7 The failure of one power amplifier shall not lead to the failure of the whole broadcast system.

8 The failure of one loudspeaker shall not lead to the failure of the whole broadcast zone.
 
9 Other ENFs of emergency broadcast system shall be in accordance with those specified in Table 3.2.5.
Table 3.2.5 Other ENFs of emergency broadcast system
Class Other ENFs



Class 1 ● with the interface linking with emergency control center (firefighting center)
● zoning override alarm compatible with firefighting zones
● automatic switch between primary/standby power supplies
● automatic switch between master/standby power amplifiers
● supporting the call stations with airing priority ranking
● supporting remote control and monitor
● supporting standby host unit
● generating running logs automatically

Class 2 ● zoning override alarm compatible with emergency control system (firefighting or manual alarm system)
● automatic switch between master/standby power amplifiers

Class 3
● can be overridden by emergency broadcast and sirens
● fault warning for power amplifier

3.3 Electro-acoustic performance indexes

3.3.1 The electro-acoustic performance indexes of PAS in every service zone shall be in accordance with those specified in Table 3.3.1.
Table 3.3.1 Electro-acoustic performance indexes of PAS

Index           Performance Type	ENSPL	Sound field irregularity (indoor)	Leak out acoustic attenuation	System SNR	STIPA	Transmission frequency response (indoor)
Business announcement system, class 1	≥83 dB	≤10 dB	≥15 dB	≥70 dB	≥0.55	Figure 3.3.1-1
Business announcement system, class 2		≤12 dB	≥12 dB	≥65 dB	≥0.45	Figure 3.3.1-2
Business announcement system, class 3		－	－	－	≥0.40	Figure 3.3.1-3
Background broadcast system, class 1	≥80 dB	≤10 dB	≥15 dB	≥70 dB	－	Figure 3.3.1-1
Background broadcast system, class 2		≤12 dB	≥12 dB	≥65 dB	－	Figure 3.3.1-2
Background broadcast system, class 3		－	－	－	－	－
Emergency broadcast system, class 1	≥86 dB*	－	≥15 dB	≥70 dB	≥0.55	－
Emergency broadcast system, class 2		－	≥12 dB	≥65 dB	≥0.45	－
Emergency broadcast system, class 3		－	－	－	≥0.40	－

* The ENSPL of emergency broadcast shall meet the requirements stipulated in item 2, article 3.2.5 of this code.
 
3.3.2 For indoor PAS, the relevant architectural acoustic characteristics should comply with the
 
requirements of current national standards GB/T 50356, Code for architectural acoustical design of theater, cinema, and multi-use auditorium and JGJ/T 131, Specification for acoustical design and measurement of gymnasium and stadium.
3.4 System configuration

3.4.1 The purpose and class of PAS shall be determined based on user's requirements, system scale and budget, etc.
3.4.2 PAS may be configured in passive terminal mode, active terminal mode, or a mode combined with passive and active terminal according to the actual situations.
3.4.3 The setting of broadcast zone shall be in accordance with the following requirements.

1 Zoning of emergency broadcast system shall be compatible with firefighting zones.

2 A building may be zoned by floors. A venue may be zoned by departments or functional modules. A corridor may be zoned by its structure.
3 Administrative departments and public areas should be zoned separately.

4 For important departments or places where the volume of loudspeakers needs to be adjusted by onsite personnel, zoning should be set separately.
5 The total power of all loudspeakers in one zone should not be too high and shall be adaptable to the capacity of zoning device.
3.4.4 The control and monitor center of PAS shall be in accordance with the following requirements.
1 Power amplifier or pre-amplifier may be also used as the control and monitor center of PAS class 3.
2 The control and monitor center of PAS class 1 or class 2 should be configured in a control and monitor room (or a station), and the performance of the control and monitor host shall meet the requirements of section 3.2 of this code.
3 If necessary, a master control center and several sub-control centers may be configured. The sub-control center may be a secondary control host or a call station.
3.5 Transmission lines

3.5.1 PA signal shall be transmitted through wired broadcasting cable, coaxial cable, Cat.5 cable, or optical cable laid in the service zone.
3.5.2 PA signal may be transmitted through wireless network, but the transmission shall not interfere with other systems and must be approved or permitted by the local relevant radio broadcast (or wireless communication) administration department.
3.5.3 If the transmission distance is 3 km or less, ordinary cable should be used to transmit power signal. If the transmission distance is more than 3 km and the total terminal power is over 1 kW, Cat.5 cable, coaxial cable, or optical cable should be used to transmit low level signal.
 
3.5.4 If the loudspeaker is passive and the transmission distance is more than 100 m, the rated transmission voltage should be 70 V or 100 V; if the product of the transmission distance and transmission power is larger than 1 km•kW, the rated transmission voltage may be 150 V, 200 V, or 250 V.
3.5.5 Power attenuation of indoor transmission line should not be more than 3 dB (1000 Hz).

3.5.6 Emergency broadcast transmission lines and trunking (or pipes) used in the areas with fire risk shall be made of flame retardant materials.
3.5.7 PAS with outdoor transmission lines (excluding optical cables) shall be equipped with lightning protection facilities. The lightning protection and grounding of PAS shall comply with the requirements of current national standard GB 50343, Technical code for protection of building electronic information system against lightning.
3.6 Loudspeakers

3.6.1 The reproducing sound field of the loudspeakers shall be in accordance with those specified in Table 3.3.1 of this code.
3.6.2 Sensitivity, rated power, frequency response, directivity and other performance indexes of loudspeakers shall meet the requirements of the sound field design.
3.6.3 Loudspeakers distribution should be in accordance with the following requirements.

1 Loudspeakers should be configured in a decentralized way based on the principle of divisional coverage in service zone.
2 For blocky service zone with a large area, such as a square or a hall higher than 4 m, loudspeakers may be configured in a centralized way or a way combined with centralization and decentralization as required.
3 The height and angle of the mounting of the loudspeakers shall meet the requirements of the sound field design.
3.6.4 Outdoor loudspeaker shall be moisture-proof and anti-corrosion.

3.6.5 The appearance, color, structure and mounting way of loudspeakers shall adapt to the surrounding.
3.6.6 If passive loudspeakers are used and the transmission distance is more than 100 m, the constant voltage type loudspeaker with built-in line matching transformer should be used. The rated voltage of the loudspeaker shall be identical to the rated transmission voltage of the transmission line.
3.6.7 Emergency broadcast loudspeakers used in the areas with fire risk shall be in accordance with the following requirements.
1 Loudspeakers shall be made of flame retardant materials or be equipped with flame retardant back cover.
 
2 Degree of protection of the loudspeaker enclosure shall comply with the requirements of current national standard GB 4208, Degrees of protection provided by enclosure (IP code).

3.7 Power amplifiers

3.7.1 Constant voltage type power amplifier should be adopted to drive passive terminal; the nominal output voltage of the constant voltage power amplifier shall be identical to the rated transmission voltage of the transmission line.
3.7.2 The rated output power of power amplifier used for non-emergency broadcast shall not be less than 1.3 times the sum of rated power of all loudspeakers driven by the power amplifier.
3.7.3 The rated output power of power amplifier used for emergency broadcast shall not be less than 1.5 times the sum of rated power of all loudspeakers driven by the power amplifier. The total power capacity of all emergency broadcast power amplifiers shall meet the requirements for releasing emergency broadcast to all zones simultaneously.
3.8 Signal source equipment

3.8.1 Audio source equipment of PAS may include PA microphones, paging devices, alarm generators, tuners, CD players, voice file recorders, computers with analog audio signal record-and-playback interfaces and other audio signal record-and-playback devices. The equipment shall be configured based on purpose, class and actual demand.
3.8.2 The characteristics of PA microphone and its signal processing circuits shall be in accordance with the following requirements.
1 PA microphone shall be in accordance with the acoustical characteristics of speech.

2 Frequency characteristics of PA microphone should comply with the requirements of current national standard GB/T 16851, Sound systems for emergency purposes.
3 PA microphone should be able to send prompt tones. In case of being used as call station, PA microphone shall be with the function of zone selection.