| 单词 | Wavelengths, and Example Communications Applications |
| 释义 | Wavelengths, and Example Communications Applications Band Designation Frequency (Hz)1 Wavelength ( )2 Applications Audible 20 Hz – 20 kHz >100 km Acoustics Extremely Low Frequency 30 Hz – 300 Hz 10,000 km – 1,000 km Submarine Communications (ELF) Radio Infralow Frequency (ILF) 300 Hz – 3 kHz 1,000 km – 100 km Not Applicable Very Low Frequency 3 kHz – 30 kHz 100 km – 10 km Navigation, Weather (VLF) Radio Low Frequency (LF) Radio 30 kHz – 300 kHz 10 km – 1 km Navigation, Maritime Communica- tions, Information and Weather Systems, Time Systems Medium Frequency (MF) 300 kHz – 3 MHz 1 km – 100 m Navigation, AM Radio, Mobile Radio Radio High Frequency (HF) Radio 3 MHz – 30 MHz 100 – 10 m Citizens Band (CB) Radio (aka Shortwave Radio), Mobile Radio, Maritime Radio Very High Frequency 30 MHz – 300 MHz 10 m – 1 m Amateur (Ham) Radio, VHF TV, (VHF) Radio FM Radio, Mobile Satellite, Mobile Radio, Fixed Radio Ultra High Frequency 300 MHz – 3 GHz 1 m – 10 cm Microwave, Satellite, UHF TV, (UHF) Radio Paging, Cordless Telephony, Cellular and PCS Telephony, Wireless LAN Super High Frequency 3 GHz – 30 GHz 10 cm – 1 cm Microwave, Satellite, Wireless (SHF) Radio LAN Extremely High Fre- 30 GHz – 300 GHz 1 cm – 1 mm Microwave, Satellite, Radioloca- quency (EHF) Radio tion Infrared Light (IR) 300 GHz – 400 THz 1 mm – 750 nm Wireless LAN Bridges, Wireless LANs, Fiber Optics Visible Light 400 THz – 1 PHz 750 nm – 380 nm Not Applicable 74570c05.qxd 9/11/07 12:20 PM Page 165 |
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