Jump technology of communication of frequency enlarge chart
Jump frequency communication uses signal of tape carrier wave, alternate inside permission frequency range the frequency of communication is nodded constantly. Send just mix accept just maintain at any time jump frequency condition (channel) can have news report consistently.
Technology of communication of chart of straight frequency enlarge:
The byte that should send to every uses redundant encode technology. Because disturb,be in transmission process and lose, statistical relevant technology is OK also data reductive.
Infra-red communication technology:
The commerce in maturity uses this technology rarely in wireless system. Infra-red communication uses VHF, in spectrum only under visible light. Photograph light is same, infra-red cannot penetrate fraise, it includes directional transmission and diffusion to transmit two kinds of technologies. Directional transmission cost is inferior but transmission distance is closer (3 feet) . Diffusion (reflection) transmission technology conveys limits is nearly, confine indoors.
The working principle of the job of wireless network
1, the overview of wireless network product
Wireless network product uses radio wave to transmit information. Wireless sow aux will be able to to measure from send just pass the receiver that gives distant place, the data signal that should send arrives through modulation overlay in signal of wireless carrier wave, the electric wave after modulation holds certain frequency bandwidth. In the configuration of typical wireless Lan net, send / receive equipment to be called to land a spot, in receiving a local area network repeatedly with standard reticle. Say simply, land a dot to be used accept, of short duration is put, transmit data. One lands a dot to be able to manage a group user to act well inside certain limits.
Common computer user and the equipment that land bit of communication are adapter of infinite Lan net, jotter product intervenes the product of wireless Lan net is Pcmcia standard card (the applied environment such as Win95, Wince) . The product on other strike with the palm of the hand can be used compositive inside buy type is wireless product.
2, the configuration of wireless network:
The mainest wireless network, if pursue: Two computer that get stuck of wireless net can form an independent network, call a dot to join to the dot. Such network does not need to manage and be configured. Below this kind of circumstance, each client end can land another node to go up only, and cannot reach a center server. On existing local area network installation lands a spot, with respect to the communication ability of can effective patulous network node. Wireless network node can visit the other equipment on server and network at the same time. Each land a dot to be able to manage a series of Client at the same time, specific amount depends on the condition of communication. In applying at present with 15-50 differ. In certain power (measure with decibel) below communication antenna, the network lands the communication limits of the dot to have certain restriction. From radius 100 meters go to thousands of meters. In bigger applied field, can install many land a spot. The position of installation is passed in the spot monitor actually get. The shift inside limits is enclothed in the network when wireless node when, maintain call " to roam without the ability that seams communication constantly with the network " attacks to solve the develop of the network problem, the relay that can choose wireless network is patulous equipment. Relay is patulous implement function to like landing a spot. But the restriction that does not accept a local area network to connect a line. Relay is patulous implement what allude to its name place is same, will wireless signal gives other relay to expand from hookup of a of the network wireless node implement or land a spot. Relay is patulous implement can string together receive together, the place that cannot obtain line of local area network becomes an organic whole repeatedly. This some give a hand in the hand when fire fighting like people like delivering pail.
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