FRS/GMRS/MURS/CB/NWR Frequency and so on the difference
Power and Frequency
When talking about radios, the first thing that comes to anyone’s mind is range. How far can they transmit? It’s an important detail worthy of a quick discussion before we move on into the different radio services available to you for communication.
Two key variables when discussing range are power and frequency. Power output is measured in watts and the more watts your radio has the further it can transmit. Think of wattage as one of those wind up cars that you pull back on. The harder you pull back on it, the further it goes once you release it. Watts work like this too, the higher the wattage, the further your signal will travel and the less prone it will be to interruption from resistance along the way. It’s important to note that higher wattage handheld radios will also wear down your batteries faster. This all depends on the quality of radio you’re running too.
Frequency is also a big part of the range you’ll achieve on a radio. The two frequency spectrums we’ll primarily be talking about are VHF (very high frequency) 30 MHz – 300 MHz and UHF (ultra high frequency) 300 MHz – 3 GHz. The frequencies you can operate on within these spectrums vary and we’ll get into that shortly. What’s important here is that neither VHF or UHF is better, per se, each have their differences.
The lower the frequency, (VHF is lower than UHF) the longer the wavelength and typically further a signal can travel. Lower frequencies also have greater penetrating power. Don’t discount UHF though, it may have a shorter wavelength, but that can be beneficial within buildings, where a longer wavelength can hit stopping blocks and a UHF signal can find its way through nooks and crannies.
As a caveat, if you’re faced with a thick, impenetrable concrete wall, VHF is going to win and burn through it better than UHF would. But again, that’s a single wall. UHF is still possibly a better choice for indoor use and VHF might be better for outdoor use. Your mileage may vary though.
Here are the 14 FRS ultra high frequencies (UHF), which are spaced at 12 kilohertz intervals. These frequencies can be used license-free for personal or business use, as long as you’re not a representative of a foreign government.
You may be familiar with the concept of the “perfect conditions” in which most of these FRS radio companies use to tout their crazy ranges of up to 40 miles. The fact of the matter remains that the FCC regulates that FRS radios have an integral non-detachable antenna and operate with a maximum power of 1/2 of a watt. That’s 0.5 watts or 500 milliwatts. Only 5 times more power than that 80s walkie-talkie was putting out. Even the FCC states that typical range of FRS is less than a mile.
So how can companies back up their long range claims? I’d love to actually see their testing, but with a clear line of sight, the UHF range is still going to be limited to the horizon. AM radio (550 kHz – 1650 kHz) and shorter wavelengths in the sub 2 MHz range follow the earth’s curvature due to reflection off of the atmosphere and thus travel pretty far. As wavelengths get shorter with VHF and then even shorter with UHF, they generally travel in straight lines.
This is what the horizon limitation is all about with FRS. It’s possible companies achieve a huge range by elevating an antenna. Once a transmission on FRS reaches the horizon, or point at which the earth starts to curve, it will continue indefinitely in a “generally” straight line. If the antenna on the other side of that earth curvature is elevated, it’s possible to game the distance the antenna can pick up the “straight line” communication. It’s a theory, but it’s what I’m going with for now.
One last thing to mention on FRS radios is the option of setting privacy codes. There’s a whole lot of terminology here, so try not to get overwhelmed. These “codes” are known as PL Tones (Motorola trademark) and generically referred to as CTCSS (Continuous Tone Coded Squelch System) codes. They’re analog and are often numbered 1-38. Additionally, there’s a digital block of these codes known as DPL (Digital Private Line – another Motorola trademark) and generically referred to as CDCSS (Continuous Digital Coded Squelch System) codes. These are typically numbered 39-121.
These codes are primarily for interference elimination in the case where all of the 14 FRS channels are occupied within your area. For instance, you hear chatter on all 14 FRS frequencies and rather than give up, you punch in a privacy code of 19 with your radio set to channel 1 (462.5625). Now you and the other party you’re communicating with can talk without hearing the main conversation on channel 1. Of course, if another radio in the area also has the privacy code of 19 set on channel 1, they’ll hear everything you’re saying.
Here are the 23 UHF (Ultra High Frequency) GMRS channels which are spaced at 25 kHz intervals. A license is required to operate on GMRS and the licensing process is explained below.
As mentioned earlier, there are 7 frequencies above that are shared frequencies with FRS. The only difference between these frequencies on GMRS is that by having a GMRS license, you can now transmit on these 7 with a max output of 5 watts vs. the 0.5 watt limit on FRS. Hopefully you’re tracking.
Other than those 7 channels with the max 5 watt output on GMRS, the other 16 channels have a max output of 50 watts! Most handheld GMRS capable radios only have 1-5 watts of available power though.
The downside to GMRS is the licensing required, but I was surprised at just how easy it was to do. It took me all of 10 minutes to do and cost me $90. It’s a 5-year license that’s available to anyone 18 years or older and not a representative of a foreign government. The plus side is that once you get a license, any family member, regardless of age, can operate GMRS stations and units within your licensed system.
In 2010 a proposal was introduced to eliminate the licensing requirement to operate on GMRS frequencies, but as of this date that proposal is still pending. To get your GMRS license simply head to the FCC Universal License System (ULS) website and register. Once you’re setup with an account, just click on the option to “apply for a new license.” Next, select “ZA – General Mobile Radio (GMRS)” and follow the instructions.
Here are the 5 MURS frequencies which are spaced at 11.25 kHz or 20.00 kHz intervals.
151.820 MHz (11.25 kHz)
151.880 MHz (11.25 kHz)
151.940 MHz (11.25 kHz)
154.570 MHz (20.00 kHz)
154.600 MHz (20.00 kHz)
A few other benefits of operating on MURS frequencies are the ability to have detachable antennas and use an external antenna of up to 20 ft. (6.1 meters) above a structure, or 60 ft. (18.3 meters) above the ground, whichever is higher. MURS can’t be used with repeaters though. You’ll also find the ability to set privacy codes on MURS frequencies like I described earlier with FRS radios.
Here are the 40 HF (High Frequency) 27 MHz CB Frequencies authorized for use with a maximum 4 watt output (AM) or 12 watt output in Single Side Band (SSB) as measured at the antenna connector on the back of the radio.
27.065 *Emergency Use Only*
When talking on a CB radio, you can’t talk with another station for more than 5 minutes continuously before waiting at least one minute before starting another communication. Channel 9 is restricted by the FCC as an emergency communication and roadside assistance channel only. The typical conversation channel on CB is 19, where you’ll often find truckers and highway travelers providing information on traffic, construction and accidents. It can be a great way to find out what’s going on ahead of you on the highway when traveling.
Here are the 7 VHF weather frequencies that NOAA broadcasts on. Use this link to find out what station you’ll need to tune into locally.
In addition to the weather, you’ll also hear hazard warning broadcasts and post-event information. This includes natural disaster (earthquakes or avalanches), environmental issues (chemical releases or oil spills) and public safety messages (AMBER alerts or 911 Telephone outages).
These weather frequencies use 1,025 transmitters that cover all 50 states, adjacent coastal waters, Puerto Rico, the US Virgin Islands and the US Pacific Territories. This makes them readily accessible in US territorial waters and you’ll likely find them on most marine VHF radios.