|
UHF CB is a class-licensed citizen's band radio service authorised by the governments of Australia, New Zealand, Vanuatu, and Malaysia in the UHF 477 MHz band.〔Jim Sinclair ''Radio Signal Finding'' McGraw-Hill Professional, 2000 ISBN 0-07-137191-5 page 281〕 UHF CB provides 77 channels, including 32 channels (16 output, 16 input) allocated to repeater stations. It is similar in concept to 27 MHz CB Radio in the United States, Australia, and New Zealand. Class Licensing means that users do not have to apply for a license or pay a license fee however they must comply with the regulations of the class licence. 〔http://www.acma.gov.au/Citizen/Consumer-info/All-about-spectrum/Marine-and-Amateur-Radio/citizen-band-radio-service-cbrs-fact-sheet〕 User equipment designs are similar to commercial land mobile two-way radio except the maximum legal output power is 5 watts. External antennas are permitted and commercially manufactured antennas have gains as high as 12 dB. Handheld transceivers (walkie talkies) are permitted and have transmit power from 500 mW to 5 W (full legal power) and are relatively cheap compared to full-sized transceivers. It is illegal to use non-standard radios purchased from overseas because they interfere with licensed land-mobile services. This includes overseas personal radio service devices because they do not share the same band plan, power output and channels as UHF CB. Care must be taken when importing radios from overseas to ensure they comply with local regulations. Approved radios are identified by an Australian standards C Tick usually found on the tag or sticker of the radio. ==Scan== Many UHF CB radios allow the user to scan channels to find a conversation. Several different scan modes may be provided: Open Scan scans all 80 channels to find an active conversation. Some radios allow skipping selected channels when scanning. Group Scan scans a small number of selected channels. For example, a caravanner travelling around the country may choose to group scan Channel 40 (Road Channel), 18 (Caravan Channel) and 5 (Emergency Channel) so they will hear any conversations relating to their travels. Priority Scan allows selection of a "Priority" channel whilst scanning a handful of selected channels. This could be useful in a convoy of cars where vehicles can set their own convoy channel as a priority channel whilst scanning the designated road channel for traffic updates, if a member from their convoy speaks, the radio will always switch back to the priority channel even if someone is speaking on another channel. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「UHF CB」の詳細全文を読む スポンサード リンク
|