User:Hoyalang/Sandbox/NG1
家庭無線電服務（Family Radio Service，簡稱：FRS）是 improved walkie-talkie radio system authorized in the United States since 1996. This personal radio service uses channelized frequencies around 462 and 467 MHz in the ultra high frequency (UHF) band. It does not suffer the interference effects found on citizens' band (CB) at 27 MHz, or the 49 MHz band also used by cordless telephones, toys, and baby monitors. FRS uses frequency modulation (FM) instead of amplitude modulation (AM). Since the UHF band has different radio propagation characteristics, short-range use of FRS may be more predictable than the more powerful license-free radios operating in the HF CB band.
Initially proposed by RadioShack in 1994 for use by families, FRS has also seen significant adoption by business interests, as an unlicensed, low-cost alternative to the business band.
Worldwide, a number of similar personal radio services exist; these share the characteristics of low power, operation in the UHF (or upper VHF) band using FM, and simplified or no end-user licenses. Exact frequency allocations differ, so equipment legal to operate in one country may cause unacceptable interference in another.
技術規格
[编辑]FRS radios use narrow-band frequency modulation (NBFM) with a maximum deviation of 2.5 kilohertz. The channels are spaced at 25 kilohertz intervals, with all frequencies ending in 2.5 or 7.5 kHz.
FRS radios are limited to 500 milliwatts according to U.S. Federal Communications Commission (FCC) regulations. Channels 1 to 7 are shared with low-power interstitial channels of General Mobile Radio Service (GMRS). A license is required for those channels if the power output is over FRS limits.[1]
Unlike Citizens' Band (CB) radios, FRS radios frequently have provisions for using sub-audible tone squelch (CTCSS and DCS) codes, filtering out unwanted chatter from other users on the same frequency. Although these codes are sometimes called "privacy codes" or "private line codes" (PL codes), they offer no protection from eavesdropping and are only intended to help share busy channels. Tone codes also do nothing to prevent desired transmissions from being swamped by stronger signals having a different code.
FRS stations on channels 1 through 7 may communicate with GMRS stations on those shared channels; the GMRS stations may use up to 5 watts of power, while the FRS stations are restricted to 500 milliwatts (half a watt).[1]
All equipment used on FRS must be type accepted according to FCC regulations. Radios are not type-accepted for use in this service if they exceed limits on power output, have a detachable antenna or for other reasons.[1][2]
FRS radios must use only permanently attached antennas,[1] such as walkie-talkies; there are also table-top FRS "base station" radios that have whip antennas. This limitation intentionally restricts the range of communications, allowing greatest use of the available channels. The use of duplex radio repeaters and interconnects to the telephone network are prohibited under FRS rules, unlike other radio services.
FRS manufacturers generally claim exaggerated range. The presence of large buildings, trees, etc., will reduce range. Under exceptional conditions, (such as hilltop to hilltop) communication is possible over 60 km（37 mi） or more, but that is rare. Under normal conditions, with line of sight blocked by a few buildings or trees, FRS has an actual range of about 0.5 to 1.5 km (0.3 to 1 mile).
FRS/GMRS hybrid radios in the United States
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Hybrid FRS/GMRS consumer radios have been introduced that have 22 channels. Many of these radios have been certified for unlicensed operation (on the 7 FRS frequencies, channels 8–14) under FRS rules.[3]
The FCC rules and statements regarding the use of hybrid radios on channels 1–7 stipulate the need for a GMRS license when operating under the rules that apply to the GMRS.[1] Many hybrid radios have an ERP that is lower than 0.5 watts on channels 1–7, or can be set by the user to operate at low power on these channels. This allows hybrid radios to be used under the license-free FRS rules if the ERP is less than 0.5 watts and the unit is certified for FRS operation on these frequencies.[1]
In the United States of America, operation on channels 15–22 requires an FCC GMRS license.[4] Interference to licensed services may be investigated by the FCC.[5]
Channels 8–14 are exclusively for FRS. Accordingly, GMRS operation is not allowed on these channels. Channels 15–22 are reserved exclusively for GMRS. As noted, FRS operation is not allowed on these channels.
頻率表
[编辑]| 頻道 | 美國 | 加拿大 | 中國 | 日本 | 南韓 | 臺灣 |
|---|---|---|---|---|---|---|
| 1 | 462.5500[6] | 462.5625 | 409.7500 | 465.0375 | 448.7500 | 467.5125 |
| 2 | 462.5625 | 462.5875 | 409.7625 | 465.0500 | 448.7625 | 467.5250 |
| 3 | 462.5750 | 462.6125 | 409.7750 | 465.0625 | 448.7750 | 467.5375 |
| 4 | 462.5875 | 462.6375 | 409.7875 | 465.0750 | 448.7875 | 467.5500 |
| 5 | 462.6000 | 462.6625 | 409.8000 | 465.0875 | 448.8000 | 467.5625 |
| 6 | 462.6125 | 462.6875 | 409.8125 | 465.1000 | 448.8125 | 467.5750 |
| 7 | 462.6250 | 462.7125 | 409.8250 | 465.1125 | 448.8250 | 467.5875 |
| 8 | 462.6375 | 467.5625 | 409.8375 | 465.1250 | 448.8375 | 467.6000 |
| 9 | 462.6500 | 467.5875 | 409.8500 | 465.1375 | 448.8500 | 467.6125 |
| 10 | 462.6625 | 467.6125 | 409.8625 | 465.1500 | 448.8625 | 467.6250 |
| 11 | 462.6750 | 467.6375 | 409.8750 | 468.5500 | 448.8750 | 467.6375 |
| 12 | 462.6875 | 467.6625 | 409.8875 | 468.5625 | 448.8875 | 467.6500 |
| 13 | 462.7000 | 467.6875 | 409.9000 | 468.5750 | 448.9000 | 467.6625 |
| 14 | 462.7125 | 467.7125 | 409.9125 | 468.5875 | 448.9125 | 467.6750 |
| 15 | 462.7250 | 409.9250 | 468.6000 | 448.9250 | ||
| 16 | 467.5500 | 409.9375 | 468.6125 | 449.1500 | ||
| 17 | 467.5750 | 409.9500 | 468.6250 | 449.1625 | ||
| 18 | 467.6000 | 409.9625 | 468.6375 | 449.1750 | ||
| 19 | 467.6250 | 409.9750 | 468.6500 | 449.1875 | ||
| 20 | 467.6500 | 409.9875 | 468.6625 | 449.2000 | ||
| 21 | 467.6750 | 468.6750 | 449.2125 | |||
| 22 | 467.7000 | 468.6875 | 449.2250 | |||
| 23 | 467.7250 | 468.7000 | 449.2375 | |||
| 24 | 468.7125 | |||||
| 25 | 468.7250 | |||||
| 26 | 468.7375 | |||||
| 27 | 468.7500 | |||||
| 28 | 468.7625 | |||||
| 29 | 468.7750 | |||||
| 30 | 468.7875 | |||||
| 31 | 468.8000 | |||||
| 32 | 468.8125 | |||||
| 33 | 468.8250 | |||||
| 34 | 468.8375 | |||||
| 35 | 468.8500 |
註釋
[编辑]- 美國聯邦通信委員會核定頻道1-7可與GMRS共用
- 中國包含香港、澳門2地
參考來源
[编辑]- ^ 1.0 1.1 1.2 1.3 1.4 1.5 引用错误：没有为名为
FCC-GMRS-vs-FRS的参考文献提供内容 - ^ http://www.fcc.gov/encyclopedia/family-radio-service-frs
- ^ FCC: Wireless Services: Family Radio Service: Family Home
- ^ http://wireless.fcc.gov/services/index.htm?job=service_home&id=general_mobile General Mobile Radio Service, retrieved 2011 01 31
- ^ EB - Spectrum Enforcement Division. Federal Communications Commission. 26 January 2010 [31 January 2011].
The Spectrum Enforcement Division is responsible for resolution of complaints involving public safety and technical issues such as tower registration, marking and lighting and equipment requirements. The Division is also responsible for taking enforcement actions regarding such violations as unauthorized construction or operation of radio stations.
- ^ General Mobile Radio Service (GMRS). Federal Communications Commission. 2017-04-11 （英语）.
相關條目
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外部連結
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