There are two major formats for two-way radios. They are Ultra High Frequency (Uhf) radio and Very High Frequency (Vhf) radio. Neither frequency band is inherently great than the other. They each have their pluses and minuses. Both formats are efficient ways to chronicle with other person. But how do you resolve which one will fit your needs? Let's go over the key components of both frequencies to help you decide.
Two-way radios chronicle with each other through use of radio waves. Radio waves have separate frequencies, and by tuning a radio receiver to a exact frequency you can pick up a exact signal.
Radio waves are transmitted as a series of cycles, one after the other. You will all the time see the "Hz" abbreviation used to indicate the frequency of a radio. Hertz is equal to one cycle per second.
Radio waves are measured by kilohertz (kHz), which is equal to 1000 cycles per second, or megahertz (Mhz), which is equal to 1,000,000 cycles per second--or 1000 kHz. The connection between these units is like this: 1,000,000 Hertz = 1000 kilohertz = 1 megahertz.
You may also hear the term "wavelength" when you hear about radio waves. This term is from the early days of radio when frequencies were measured in terms of the distance between the peaks of two consecutive cycles of a radio wave instead of the amount of cycles per second. Lower frequencies yield a longer wavelength.
While wavelength measures distance between the peaks of cycles, frequency refers to how long the measured time is between the "crest" and "trough" of a wave arriving at the source. So frequency measures time instead of distance, but they are essentially both saying the same thing.
What is requisite about wavelength for two-way radios is that it affects transmission range under confident conditions. A longer wavelength as a general rule lets a radio signal travel a greater distance.
Lower frequencies or wavelengths have greater penetrating power. That's one of the reasons they are used for communicating with submarines. Vlf radio waves (3-30 kHz) can jab sea water to a depth of practically 20 meters. So a submarine at shallow depth can use these frequencies.
So from what you read above you may think Vhf is all the time the great option for a two-way radio no matter where you are using it. That's not necessarily true. Even though Vhf has great penetrating capabilities, that doesn't necessarily make it the great option for buildings. Remember the conversation about wavelength above? Wavelength has a big impact on transmission.
To elucidate this let's assume we are communicating from one side of a commercial construction to the other. In between these two points is a metal wall with a three foot door in it. Metal is an enemy to radio waves and they typically don't pass through it.
For our example let's assume that the Uhf wavelength the radio uses is about a foot and a half long and a similar Vhf radio is colse to five feet long. These are in the ballpark of their general wavelengths.
When the Uhf transmits its signal the foot and a half long wave will pass through the door since the door is wider than the wavelength. The Vhf signal will be totally reflected since it is wider than the opening to the door.
Your microwave oven is an example of this. The glass front door has a metal mesh with very small holes. Microwaves being a very high frequency have wavelengths that are only some inches long. The mesh keeps the microwaves trapped in the oven but it allows you to see inside because light waves have a slight wavelength.
Just dream walking through the construction carrying a five foot wide pole. You will encounter the same challenges a Vhf signal encounters. Now dream walking through the construction with a pole that's only a foot and a half wide like a Uhf wave. There are lots fewer doorways you couldn't get through.
The one difference is that wireless signals will jab through drywall, masonry, human bodies, furniture, wall paneling, and other solid objects. All these objects will reduce the signal vigor though. The more dense the object, the more it reduces the signal. Vhf will jab these obstacles great than Uhf, but that doesn't necessarily mean that Vhf is great for indoor applications as we will talk about in the Uhf section below.
In our example above we assumed you had a metal wall with an opening. If you reverse this and you have a three foot metal object in front of the transmitting radio, then Vhf would win. Since the object is three foot wide it will totally block the Uhf signal whereas the Vhf signal will get colse to it. Lower frequencies such as Vhf diffract colse to large smooth obstacles more easily, and they also travel more indeed through brick and stone.
For most applications, lower radio frequencies are great for longer range. A broadcasting Tv hub illustrates this. A typical Vhf hub operates at about 100,000 watts and has a coverage radius range of about 60 miles. A Uhf hub with a 60-mile coverage radius requires transmitting at 3,000,000 watts.
So there is no clear option for which is better, Vhf or Uhf. There is a lot of "black magic" to radio technology so it's not all the time easy to tell which will work great for your application. To help you resolve on the best technology for you, more detail about each one is included below.
Uhf Radio
Uhf tool operates between the frequencies of 300 Mhz and 3000 Mhz. Until recently, it wasn't widely used. Now, the Uhf radio frequency is used for Gps, Bluetooth, cordless phones, and WiFi.
There are more ready channels with Uhf so in more populated areas Uhf may be less likely to have interference from other systems. If you are in an area where habitancy is thin, Vhf should work fine for you. Not too long ago the Fcc also opened up a new Vhf frequency called Murs that is so far not heavily used in most areas. There's more about Murs below in the Vhf section. If you are in an area where interference from other radios may be an issue, Uhf transmitters and receivers could be your best option unless you use a Murs Vhf radio. Uhf is great at squeezing through bodily barriers like walls, buildings, and rugged landscape. Anything that obstructs a radio wave, will weaken a radio signal. Uhf lessens that effect. Though it may not travel as far, Uhf radio waves will traverse colse to obstacles great than Vhf.
To highlight the differences in indoor range, below is an citation from a brochure of a prominent two-way radio maker on the startling range of one of their lines of handheld Vhf and Uhf two-way radios:
"Coverage estimates: At full power, line-of-sight, no obstructions the range is practically 4+ miles. Indoor coverage at Vhf is practically 270,000 sq ft and 300,000 sq ft at Uhf. Expect about 20 floors vertical coverage at Vhf and up to 30 floors at Uhf. Note: Range and coverage are estimates and are not guaranteed."
Vhf waves are not very good at seeing their way colse to walls, buildings and rugged landscape. Therefore range will be significantly reduced for Vhf radios in these environments. That may not necessarily be a problem if the range needed is only a few hundred feet. You can also add an external antenna to an indoor Vhf base hub that will reduce or eliminate this problem.
One of the downsides to Uhf is that the Fcc requires you to get a license to control in these frequencies. Although many frequencies in the Vhf business band also wish a license. If you choose a radio in the Vhf Murs frequencies you can control it without a license. Uhf tool is normally more expensive. The components need to be finely tuned and are more expensive to construct. This does not mean it's necessarily better, just more expensive.
One benefit of Uhf transmission is the physically short wave that is produced by the high frequency. That means the antenna on the radio can be shorter than an equivalent Vhf radio.
Vhf Radio
Vhf tool operates between the frequencies of 30 Mhz and 300 Mhz. Fm radio, two-way radios, and television broadcasts control in this range.
Both Uhf and Vhf radios are prone to line of sight factors, but Vhf a slight more so. The waves make it through trees and rugged landscapes, but not as well as Uhf frequencies do. However, if a Vhf wave and a Uhf wave were transmitted over an area without barriers, the Vhf wave would travel practically twice as far. This makes Vhf easier to broadcast over a long range. If you are working mostly outdoors, a Vhf radio is probably the best choice, especially if you are using a base hub radio indoors and you add the external antenna.
Since Vhf has been colse to longer and isn't as involved to make, tool is normally cheaper when compared to similar Uhf equipment. One disadvantage to this tool can be its size. Since the frequency waves are bigger, an antenna must be bigger.
Vhf radios also have a smaller amount of ready frequencies. Interference with other radios could be more likely to be a problem. However, the Fcc recently made this less of a problem when they opened up the Murs frequencies. The 150 Mhz frequency is a Citizens Band radio spectrum that is called the Murs service. Murs stands for Multi-Use Radio Service. This assistance is for use in the United States and Canada. It is a low power, short range assistance in the Vhf 150 Mhz Citizens Band radio spectrum. There are 5 channels in the Murs frequencies with 38 privacy codes under each one that enable you to only pick up conversations on your code. The Fcc does not wish users of products for Murs to be licensed.
With Murs you can add a larger or external antenna to heighten range. If you want to put an antenna on top of your house or business, you can do it with Murs. Some antenna manufacturers claim an external antenna can growth the efficient radiated power of a transmitter by a factor of 4. These Murs intercoms can forward up to four miles, and perhaps more with an external antenna depending on the terrain.
One benefit of Vhf wireless radios is that battery life is practically all the time great than for similar Uhf units. For handheld radios this is a plus.
Vhf tool is normally lower cost for those on a budget. tool can be more prudent than similar Uhf products.
In summary, if you are planning on using your two-way radios mainly inside buildings, then Uhf is likely the best clarification for you. If you are mainly using your two-way radios for transportation outside, then Vhf would be a good choice. Whether radio technology can work for you if you don't indeed have a long range to cover. In that case you may want to choose Vhf for it's lower cost.
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