Technical Requirements For MMDS

- Apr 04, 2019-

According to international communication standards, the MMDS channel configuration should be in line with international standards. In the frequency band 2503-2687MHz, 23 TV channels are arranged at intervals of 8 MHz bandwidth per channel. And in the 2684-2700MHz dedicated frequency band, used for data and voice communication transmission and two-way transmission of uplink backhaul. In the 200MHz bandwidth, it is divided into two independent groups in a comb mode, the A group adopts an odd channel number, and the B group uses an even channel number, arranged in a channel.

As a primary power transmission system, the MMDS system should have two independent power supplies or self-supplied generators, and be equipped with an AC regulated power supply. The output voltage power supply should be free of a short pulse voltage, or a ferromagnetic regulator can be used to suppress various surge voltages and induced voltages from the power supply during lightning strikes.

The MMDS system microwave station must be reliably grounded. According to the requirements of international communication standards: the grounding resistance of the transceiver antenna system should not exceed 4Ω; the grounding resistance of the technical room should not exceed 4Ω; the grounding resistance of the equipment system should be less than 4Ω; set in the tower (or high-rise building) The grounding resistance of the equipment should be less than 4Ω; the working grounding system, protective earthing system and lightning protection grounding system of the MMDS system should be divided into grounding bodies, and then the three grounding bodies should be connected into one total grounding system.

The MMDS system must have good lightning protection facilities. The power supply lines and communication lines must also have lightning protection measures. When lightning strikes, it generates huge energy. In addition to directly passing to the ground, it can also generate inductive electricity into the electronic equipment through long transmission lines. Therefore, the transmission line of the transmitter home transmitting antenna of the MMDS system should be installed with a stainless steel grounding clamp every 1~2 meters. The upper and lower ends should be connected to the metal structure of the tower and then connected to the grounding system at the bottom of the tower.