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First, understand the project scale and status and design principles
1. On-site inspection of the customer's geographical environment, including building structure, total floor area, floor height, basement area, and whether or not elevators need to be covered.
2. Whether the engineering building is not being renovated or is in use. If all kinds of decoration work have been completed, it is necessary to pay attention to the coordination and beauty of the wiring and the building as a whole, which will increase the difficulty and amount of engineering.
3. In the process of engineering design and construction, try to consider that the equipment is installed securely, feeders are laid easily and easily, and the antennas are laid out reasonably. It is necessary to make the signal evenly distributed, and to ensure reliability and beauty.
4. On the premise of meeting the design requirements, try to use a lower output power to achieve good coverage. Refer to the "Sanitary Standards for Environmental Electromagnetic Waves" issued by the Ministry of Health of the People's Republic of China to protect the physical and mental health of surrounding people as much as possible.
5. In the design, try to make the indoor field strength uniform and have sufficient signal strength.
6. Consider the subsequent system expansion and multi-frequency point signal coverage. All equipment and indoor antennas use multi-frequency point devices and cable interfaces, and design a certain power allocation margin.
1. Number of channels: According to the number of user interphones and grouping requirements, according to the predicted traffic volume, the general use of about 80-100 radios per channel is appropriate.
2. Anti-interference: Due to the frequency limitation, the sub-audio is generally used to isolate external co-channel interference.
3. Connectivity rate in wireless coverage area: It is required that in the wireless coverage area, 95% of the location and 99% of the time can access the network.
4. Field strength at the edge of wireless coverage: 95% of the area signal strength is ≥-93dBm.
5. Switching relationship: There is a good uninterrupted switching between the indoor coverage station and the surrounding areas.
6, call quality: indoor coverage area call quality (Rx Quality) level 3 and below areas reach more than 95%.
Third, the design ideas and plans are finalized
1. Signal source: The relay station (transition station) generally uses mature products from Motorola and Hytera. For the convenience of installation and the reasonable use of the cabinet design.
2. Indoor distributed devices: Due to the high power of repeaters (relays), passive antennas and distributors are generally used. Commonly used devices are couplers, power dividers, ceiling antennas, and vehicle antennas.
3. Signal distribution: Signals are distributed to each layer and area through branch equipment. The specific distribution depends on the actual situation to ensure good communication performance for indoor users.
4. Marginal field strength: Considering the signal propagation characteristics of the repeater (transponder), the indoor signal attenuation margin is usually about 20dB, and a certain noise reserve is reserved. Therefore, the field strength of indoor coverage at 400MHz should usually be greater than -93dBm to ensure good communication for indoor users.
5. Field strength simulation test, calculation and result analysis in the coverage area.
6. Output repeater solution.
Our company provides wireless intercom system design, survey, construction, operation and maintenance, inspection and maintenance of large wireless private network systems, communication support for large events, technical guidance and consulting of wireless intercom systems, and operator and technical training. Wireless intercom problems and solutions and contact communication, Mr. Chen 13825068040 (same number on mobile phone WeChat), 3548484588 (QQ).