Solution of wireless intercom system in Commercial Plaza

The commercial plaza includes shopping malls 、 Office buildings 、 The hotel 、 Apartments and mansions , And parking lots and other supporting functional facilities . Wireless trunking communication system is divided into large-scale communication systems 、 The mall 、 Three management modes of the hotel ( group ). Each format of communication requires relative independence . Each format has two to five departments , Their communication will not interfere with each other . under these circumstances , Large property can dispatch all interphone functions , Including hotels and shopping malls .

The communication effect covers the whole bottom layer 、 The basement 、 Communication demand of vertical elevator car and nearby outdoor area , Realize the full coverage of wireless communication network . In the above areas , You can talk to each other using the walkie talkie . According to the actual situation and the current use of wireless frequency , You can choose 400MHz The frequency band is used as the wireless communication frequency of the building . Because the wireless trunking mode is adopted in the walkie talkie communication system, the division of walkie talkie communication channel is solved , Therefore, it is necessary to apply for two groups of RF , Adopt combined branching mode , The wiring structure of the system remains unchanged .

The design of the system enables the signal to effectively cover the public parts of buildings and areas with frequent personnel activities , So that the whole system can achieve unified coverage , Clear signal 、 Stable 、 reliable . The scheme needs to be able to ensure that the above requirements meet the internal management of the building 、 Property use and maintenance , And security 、 fire 、 Requirements for emergency communication, etc , For internal management 、 maintain 、 Security , And firefighters can keep in touch and communicate easily and quickly .

Design principles

① On the premise of ensuring the quality of the system , Try to adopt a low-cost method to design the scheme ;

② Reasonably set the position of the antenna 、 Quantity and output power , Ensure fewer antennas and lower output power , To achieve good coverage ;

③ Due to frequent high-level switching , High drop rate , The design shall try to achieve uniform indoor field strength , Good signal strength ;

④ Try not to use the trunk amplifier , To reduce the introduction of noise ;

⑤ Establish a perfect wireless overlay network ;

⑥ Considering that the construction is relatively easy to realize and the construction efficiency , Especially the reasonable layout and wiring ;

⑦ The link meets the requirement of more than in the coverage area 15dB Carrier to noise ratio .

working principle

The system adopts IP networking , Multiple digital relay stations form a single base station trunking communication system . Most support 8 Two voice relay channels and 16 Two data channels . The maximum user capacity can reach 800. The control channel of traditional cluster system is not required ,8 All time slots can be used , Do not waste system time slots , No application and licensing mechanisms are required . When a new call starts , Idle slots will be transferred to new idle slots , The system informs all idle walkie talkies to transfer to idle time slot , Convert the original idle time slot into a call time slot , And relay voice communication on the time slot . When the call terminates , The call slot will inform the radio of a new free slot or related slot .

System structure

According to the structure of the building , The actual situation of the surrounding electromagnetic environment is considered . Due to the wide coverage of the communication network , Including the south tower and the North Tower , There are two underground floors and interlayer , Therefore, the reinforcement technology is adopted

Concrete structure , There is obvious shielding for RF signal ( attenuation ) effect . Low coverage of wireless intercom communication . Make sure there are no communication blind spots ( spot ), The communication of wireless intercom system is normal .

The system design makes the signal in the corresponding spatial area , That is, the effective coverage area of intercom signal is aboveground buildings , The intercom signal effectively covers the equipment room of the building 、 Fire elevator 、 Safe passage and the whole outdoor building , Ensure clear communication of wireless intercom system 、 Fluent , Make the whole system realize unified coverage , Clear signal 、 Stable and reliable .

It is recommended to install trunking communication base stations in the weak current machine room on the first floor underground ( Fully automatic 、 Nobody is on duty ), And distribute the communication antenna in the following positions ： Design a channel system 、 Multiple sucker antennas and sucker free antennas , The outdoor antenna covers the whole office building , The reliability of the intercom system can be guaranteed , Ensure the wireless intercom communication between property management personnel and security personnel .

Indoor signal distribution

To meet the design requirements , And considering the difficulty of specific construction , Select the most reasonable line for repeater wiring and layout , Achieve uniform indoor power distribution . The coverage signal in this scheme is transmitted to each floor by indoor active power distribution device through feeder . Calculate strictly according to the technical indexes of equipment and feeder , The power of indoor coverage antenna is controlled at 15dBm following , Meet the national electromagnetic environmental hygiene standard .

The omnidirectional sucker antenna for transmitting and receiving signals is placed on the top of the ceiling , It is connected to the relay station on the first floor of the machine room through a feeder . The wireless signal distribution system receives and transmits signals from the antenna , The antenna is connected with the shielded cable , Wireless intercom signal indoor distribution system solves the signal coverage of public network and special signal in the whole building .