WirelessTechnology无线防盗报警技术简介解析课件.ppt
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1、,Wireless Technology,Wireless Technology,RF Basics/射频技术基础,Wireless Technology,RF Basics/射频技术基础Wireless Techn,Wireless In Everyday Life日常生活中的无线技术,Radios/无线电TVs/电视Cordless Telephones/无绳电话Garage Door Openers/车库门开闭器Cellular phones/蜂窝电话,Wireless In Everyday Life日常生活中,Wireless Technology无线技术,RF - the spec
2、ific cycles per second of electromagnetic waves traveling through the air without wires.RF is measured in Hertz/RF的测量单位是赫兹Frequency Bands are allocated and controlled by the FCC/美国的无线频率管理机构是FCCCommon uses of RF/常见的RF应用Cell Phones - 900 MHz band/移动电话Pagers - 900 MHz band/寻呼机Garage Door Openers - 300
3、MHz band/车库门开闭器Security Systems - 300 - 900 MHz bands/安防系统,Wireless Technology无线技术RF - th,Frequency Band Designations/频段划分,Frequency Band Designation Frequency Range Min Max ELF 极低频- Extremely Low Frequency30 Hz 300Hz VF 声频- Voice Frequencies300 Hz 3000 Hz VLF 超低频 Very Low Frequency 3 KHz 30 KHz LF
4、低频- Low Frequency30 KHz 300 KHz MF 中频 Medium Frequency 300 KHz 3000 KHz HF 高频- High Frequency3 MHz 30 MHz VHF 甚高频- Very High Frequency 30 MHz 300 MHz UHF 超高频- Ultra High Frequency 300 MHz 3000 MHz SHF 特高频- Super High Frequency 3 GHz 30 GHz EHF 极高频 Extremely High Frequency30 GHz 300 GHz,Frequency Ban
5、d Designations/频段,Wireless Security Systems无线安防系统,40 MHz - 24 Wavelength, great open air range, poor structural penetration, good battery life./24英尺波长,极佳的开阔地传播距离,穿透性较差,功耗小。319.5 MHz - 36” Wavelength, good open air range, good structural penetration, good battery life./36英寸波长,空旷地带传播、穿透性和功耗均佳。900 MHz
6、- 8” Wavelength, great structural penetration, interference is also possible at 900 MHz, poor battery life./8英寸波长,穿透性极佳,干扰较多,功耗大。,Wireless Security Systems无线安防系,Wireless Transmission无线传输,To transmit information using RF a carrier and some type of modulation is required/利用RF传输信息,需要使用载波和某些调制技术Carrier
7、- the specific frequency to carry the information /载波-使用特定的频率来携带信息Modulation - the means of encoding information on the carrier frequency/调制-将编码信息处理并添加到载波上,Wireless Transmission无线传输To tr,Frequency Bandwidth频宽,Bandwidth - a measurable area that information is transferred within/带宽-一个传输信息的可测量的区域Receiv
8、ers bandwidth must be as larger or larger than the transmitters bandwidth/接收机带宽必须同发射机的带宽相同或大于发射机The closest the match the more reliable the RF path/二者越接近、越匹配则RF传输路径越可靠,Frequency Bandwidth频宽Bandwidth,Narrow Band Advantages窄波段的优势,Smaller System devices/更小的设备体积Longer Battery Life/更长的电池寿命More Reliable/更
9、可靠Low Current Consumption/较低的电流功耗Quieter Frequency/频率更安静Penetrates Buildings Better/建筑物穿透性较佳,Narrow Band Advantages窄波段的优势Sm,SAW vs Crystal 两种发生器对比,Technologies used in receiving and transmitting information/指的是接收和发送信息采用的技术SAW refers to Surface Acoustic Wave and provides good frequency accuracy at a
10、moderate cost/SAW意指声表面波技术,能提供良好的频率精确性和适中的成本Crystal, by using a quartz crystal provides the highest frequency accuracy at a slightly higher cost/石英晶体器件可提供更高的频率精确性,价格稍高,SAW vs Crystal 两种发生器对比Technolo,Dead Spots & Phase Nulls 盲点和零相位,Filing Cabinets文件柜Foil Backed Insulation背衬金属膜的隔断Mirrors镜子Metal Ductwor
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