What is the Difference Between UHF & VHF & HF and GMRS & FRS?
08 Sep. 2016 Information
UHF- Ultra High Frequency (between 300 MHz and 3 GHz)
UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, and numerous other applications. The IEEE defines the UHF radar band as frequencies between 300 MHz and 1 GHz. Two other IEEE radar bands overlap the ITU UHF band: the L band between 1 and 2 GHz and the S band between 2 and 4 GHz. One of the biggest pros of UHF radios is that they do a much better job of penetrating barriers in urban locations, like concrete, steel, and wood. So this kind of radio is best suited for use indoors, including buildings with multiple floors, in industries such as manufacturing, distribution, education, retail, hospitality, and healthcare. They also work well for businesses that function in both indoor and outdoor settings, where there are a lot of surrounding buildings.
VHF- Very high frequency (from 30 MHz to 300 MHz)
Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF). Common uses for VHF are FM radio broadcasting, television broadcasting, two way land mobile radio systems (emergency, business, private use and military), long range data communication up to several tens of kilometres with radio modems, amateur radio, and marine communications. Air traffic control communications and air navigation systems (e.g. VOR, DME & ILS) work at distances of 100 kilometres or more to aircraft at cruising altitude. VHF was used for analog television stations in the US, and continues to be used for digital television.
HF- High frequency (between 3 and 30 MHz)
The HF band is a major part of the shortwave band of frequencies, so communication at these frequencies is often called shortwave radio. Because radio waves in this band can be reflected back to Earth by the ionosphere layer in the atmosphere – a method known as "skip" or "skywave" propagation – these frequencies are suitable for long-distance communication across intercontinental distances. The band is used by international shortwave broadcasting stations (2.310 - 25.820 MHz), aviation communication, government time stations, weather stations, amateur radio and citizens band services, among other uses.
Now that you’re aware of the differences between HF, VHF and UHF radio, you can make an informed decision about which option is a better fit for your business needs. As you can see, each operational frequency comes with its own advantages and disadvantages. But overall, VHF radios are better for outdoor use in large areas, and UHF radios are better for indoor or outdoor settings that are in close proximity.
The General Mobile Radio Service (GMRS) is a land-mobile FM UHF radio service designed for short-distance two-way communication. It requires a license in United States but some GMRS compatible equipment can be used license-free in Canada.
GMRS radios are typically handheld portable devices much like Family Radio Service (FRS) radios, and share the FRS frequency band near 462 and 467 MHz. Mobile and base station-style radios are available as well, but these are normally commercial UHF radios as often used in the public service and commercial land mobile bands. These are legal for use in this service as long as they are GMRS type-approved. They are more expensive than the walkie-talkies typically found in discount electronics stores, and are generally considered higher quality.
Operating a GMRS System
A GMRS system consists of station operators, a mobile station (often comprised of several mobile units) and sometimes one or more land stations. A small base station is one that has an antenna no more than 20 feet above the ground or above the tree on which it is mounted and transmits with no more than 5 watts ERP. The use of some channels is restricted to certain types of stations.
None of the GMRS channels are assigned for the exclusive use of any system. You must cooperate in the selection and use of the channels in order to make the most effective use of them and to reduce the possibility of interference. You can expect a communications range of five to twenty-five miles. You cannot directly interconnect a GMRS station with the telephone network. Normally, you and your family members would communicate between yourselves directly or through a repeater station. The stations must be within the territorial limits of the fifty United States, the District of Columbia, and the Caribbean and Pacific Insular areas.
In transient use, a mobile station from one GMRS system may communicate through a mobile relay station (repeater) in another GMRS system with the permission of its licensee. The communications may also be with mobile stations from other GMRS systems also with permission from the licensee to communicate through the mobile relay station.
GMRS channels Along the Canadian Border
GMRS applicants must certify that they will comply with the requirement that use of frequencies 462.650, 467.6500, 462.7000and 467.7000 MHz is not permitted near the Canadian border North of Line A and East of Line C. These frequencies are used throughout Canada and harmful interference is anticipated.
The Family Radio Service (FRS) is an 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 is a private, two-way, very short-distance voice and data communications service for facilitating family and group activities. The most common use for FRS channels is short-distance, two-way voice communications using small hand-held radios that are similar to walkie-talkies.
It’s important to note that FRS radios are intended and designed for family recreational use only. These radios are basically one step beyond toys. They won’t hold up to the rigors of regular business use and are very likely to break after weeks or months if they are used daily. If you’re using radios in any business setting, it’s more cost effective in the long run to purchase durable Motorola and HQT business radios.
According to the FCC, the Family Radio Service may be “used by family, friends and associates to communicate within a neighborhood and while on group outings with a communications range of less than one mile.” No license is required. You can use your FRS unit within the US, Mexico and Canada.
GMRS and FRS Dual Service Radios
Some manufacturers have received approval to market radios that are certified for use in both GMRS and FRS. Other manufacturers have received approval of their radios under the GMRS rules, but market them as FRS/GMRS radios on the basis that:
Some channels are authorized to both services, or
A user of the device may communicate with stations in the other service.
Radios marketed as "FRS/GMRS" or "dual-service radios" are available from many manufacturers and many retail or discount stores. The manual that comes with the radio, or the label placed on it by the manufacturer, should indicate the service the radio is certified for. If you cannot determine what service the radio may be used in, contact the manufacturer. If you operate a radio under the GMRS rules, you must have a GMRS license. GMRS radios generally transmit at higher power levels (1 to 5 watts is typical) than FRS radios and may have detachable antennas.
If you operate a radio that has been approved for both FRS and GMRS, and if you limit your operations to the FRS channels with a maximum power of ½ watt effective radiated power and an integral antenna, you are not required to have a license. (Note that some dual-service radios transmit with higher power on FRS channels 1 through 7; these radios can be used without a license only on FRS channels 8 through 14.)
(Source: Wikipedia and FCC)