EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Moon Star on May 22, 2017, 09:59:19 am
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My husband and I are like a couple of big kids, and we want a pair of walkie talkies to communicate when we are on opposite sides of the house. I purchased a pair of DuaFire. They had good reviews and were inexpensive.
Out of the box are these legal to use in the US? Seems like a lot of people use them, but some say they are not legal unless re-programmed. I did purchase a USB cable to be able to program them. If I need to re-program, what do I program them to? I can't find much information doing Google searches.
Any help would be appreciated!! :-+
DuaFire
Model: DF09042
Frequency Range: 462-467Mhz
RF Rated Power: less than 0.5w
Channel Capacity: 20
Operated Voltage: 3 AAA batteries
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Perfectly legal. They are in the Family Radio Service band and are at the 500mW power limit. See https://en.wikipedia.org/wiki/Family_Radio_Service (https://en.wikipedia.org/wiki/Family_Radio_Service). Now, if you were to try to increase the power or re-program the frequencies, then there may be an issue.
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how is the US Family Radio Service different from the old Citizens band radio Service? less power.
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The FRS uses UHF frequencies in the 460-470 MHz range, and the common CB equipment operated on HF frequencies around 27 MHz.
FRS uses FM modulation, and a maximum output power of 500 mW. CB uses AM or SSB modulation, with a 4W carrier or 12W PEP output power limit.
If your radios cover channels 15-22, you need a GMRS license to legally transmit on those channels. Unlicensed FRS operation is allowed only on channels 1-14.
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FRS will cross the street, CB will cross the ocean on a good day!!
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The FRS uses UHF frequencies in the 460-470 MHz range, and the common CB equipment operated on HF frequencies around 27 MHz.
FRS uses FM modulation, and a maximum output power of 500 mW. CB uses AM or SSB modulation, with a 4W carrier or 12W PEP output power limit.
If your radios cover channels 15-22, you need a GMRS license to legally transmit on those channels. Unlicensed FRS operation is allowed only on channels 1-14.
so it looks like CB is still using the old AM 27 MHz. band in the US.
As here in Australia CB citizen band radio has two bands,
the old AM/SSB 40 channel 27MHz band (26.965 – 27.405 MHz), maximum rf power 4 watts AM, - 12 watts SSB.
and the new or now used FM 80 channel 476.4125 – 477.4125 MHz UHF band. UHF CB radio units can use repeaters & send data too. maximum rf power 5 watts. walkie talkies or mobile /base station.
I do see that many cheap walkie talkies are just 0.5 watts with the full 80 channel's
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You should be confused as mfgs have really muddied the waters with their product configurations. I looked up your radio and found it had 22 channels. That means it covers both FRS and GMRS. The GMRS only frequencies require a license. Below is a a typical frequency list. Note that a GMRS license covers the entire family for 5 years, and is about $70.
FRS/GMRS
01 462.5625
02 462.5875
03 462.6125
04 462.6375
05 462.6625
06 462.6875
07 462.7125
FRS ONLY
08 467.5625
09 467.5875
10 467.6125
11 467.6375
12 467.6625
13 467.6875
14 467.7125
GMRS ONLY, license required
15 462.550
16 462.575
17 462.600
18 462.625
19 462.650
20 462.675
21 462.700
22 462.725
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In addition to the difference in frequencies, GMRS allows higher power and repeater use on certain channels. Also, it allows higher bandwidth (5 kHz FM deviation) versus FRS (2.5 kHz FM deviation)
Depending on the bandwidth used by the radio (I can't find its specifications), you may need a GMRS license to use the "shared" channels.
Find the FCC ID, and then search the FCC databases to see what they reported about its specifications.
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FRS does NOT require any license in the US, and can go quite a distance. For example, its 500 mw is enough to communicate from one side of a mall to the other even with some buildings in between, sometimes. I have two Motorola FRS handheld transceivers and they have communicated with one another while more than a mile apart in Yosemite valley and at Chaco Canyon while camping. Note that both were valleys which may have contained and reflected some of the signal.
If you are technically literate, you might consider both getting a ham license. Then you can communicate much farther - participate in a community of radio amateurs and exponentially more fun.
Don't screw around with unlicensed operation of better radios than is legal. FRS are legal unlicensed. Most GMRS radios also have FRS, use that until you have a license.
Ham license does not include GMRS, they are separate animals. Also its my understanding that ham equipment should never be used on GMRS or FRS even if its capable of doing so physically.
How does the new (digital data friendly?) MURS fit in? I would be interested in hearing more on that.
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There is no narrow band FM on 27MHz CB in the US? We used to have the opposite - only FM and no AM/SSB at all allowed.
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this may help - or make things worse >:D
http://ukspec.tripod.com/rf/handheld.html (http://ukspec.tripod.com/rf/handheld.html)
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Yeah the range on FRS radios can be impressive. I have the frequencies in my scanner and frequently hear random people talking. Sometimes neighborhood kids, other times it's people in cars on the highway across the valley.
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I was also confused after reading your heading. Why it will be illegal? I am using it from last two years. Actually, I bought my first walkie talkie after reading this walkie talkie review https://totalguide.org/best-walkie-talkie/ article. I didn't know much that time about 2 ways radio. But, now i need it for my daily work. I didn't find any law yet which will tell it is illegal in the USA.
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You should consider both getting a ham license. Then you can communicate much farther - participate in a community of radio amateurs and exponentially more fun.
That's serious overkill for two people who just want to talk to each other from opposite sides of the house. And it would make the conversations more cumbersome with all the callsign announcements. A pair of cheap FRS radios are a much more appropriate solution.
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The FCC has recently announced changes to the rules (not yet in effect) which will make most of the GMRS channels on the "dual service" radios OK to use without getting a license.
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That sounds cool, I'll have to look into the details... I suspect there will still be the 50mW fixed antenna limitation?
Edit: Cool, now I can use my 2W radios...
http://www.arrl.org/news/fcc-personal-radio-service-revisions-will-affect-gmrs-frs-cb-other-part-95-devices (http://www.arrl.org/news/fcc-personal-radio-service-revisions-will-affect-gmrs-frs-cb-other-part-95-devices)