Two-way radios contain two main formats. They are ultra high frequency (UHF) radio and very high frequency (VHF) radio. Neither the frequency band is much better than the other. Each one has plus and minus. Both formats are an effective way of communicating with another person. But how do you decide which one meets your needs? Let's go through the key elements of both frequencies to help decide.
Two-way radios communicate with each other using radio waves. Radio waves have different frequencies and tuning a radio signal to a given frequency
Radio waves are transmitted sequentially to cycles. You will always see the abbreviation "Hz" for signaling the radio frequency. Hertz equals one cycle per second.
Measures radio waves in kilohertz (kHz) equal to 1000 cycles / second or MHz (MHz) equal to 1 000 000 cycles per second or 1000 kHz. The connection between these units is as follows: 1.000.000 Hertz = 1000 kilohertz = 1 megahertz
We also hear the wavelength of radio waves. This term comes from the initial days of the radio when the frequencies are determined in the two consecutive cycles by the distance of the radio wave peaks, instead of the number of cycles per second. Lower frequencies result in longer wavelengths
While the wavelength measures the distance between the peaks of the cycle, the frequency indicates how much time is between the "source" and "trough". Thus, the frequency determines the distance rather than the time, but essentially both say the same.
The importance of bi-directional radios is that they influence the transmission range under certain conditions. Longer wavelength than general rule allows the radio signal to travel longer.
Lower frequencies or wavelengths provide higher throughput performance. This is one of the reasons for communicating with submarines. The VLF radio waves (3-30 kHz) can be placed at a depth of approximately 20 meters in the seawater depth. Thus, the shallow depth submarine can use these frequencies
Thus, it is clear from the above that VHF is always a better choice for a two-way radio, no matter where it is used. This is not necessarily true. Even though VHF has more penetrating capabilities, this does not necessarily make a better choice for buildings. Do you remember talking about this wavelength? The wavelength has a great impact on transmission
This is to be explained by the fact that we communicate from one commercial side to another. Between these two points there is a metal wall with three foot openings. Metal is the enemy of radio waves and does not usually pass through it.
Our example assumes that the radio UHF has a wavelength of about one and a half meters and a similar VHF radio is about five feet long. They are in the balloon of normal wavelengths.
When the UHF transmits the signal, a foot and a half long wave pass through the door as the door is wider than the wavelength. The VHF signal is fully reflected as it is wider than the door opening.
Microwave oven is an example of this. The glass door has a metal mesh with very small holes. Microwaves are very high frequencies, wavelengths that are only a few centimeters long. The mesh retains microwaves in the oven but allows you to enter because the waves of light are microscopic wavelengths.
Just imagine walking through a building with a five foot wide pole. You will encounter the same challenges that affect a VHF signal. Now imagine walking through the building with a pole that is only one and a half feet wide than an UHF wave. There are plenty of doors you can not get through.
The only difference is that wireless signals pass through plasterboard, masonry, human bodies, furniture, wall coverings, and other solid objects. All these objects reduce signal strength. The denser the object, the more it decreases the mark. VHF is more likely to perceive these obstacles than UHF, but this does not necessarily mean that VHF is better suited for indoor applications as we will discuss at the UHF section below.
In our example above we assumed an opening. If you turn it around and there is a three-legged metal object in front of the transmitter, then the VHF wins. Since the object is three feet wide, it completely blocks the UHF signal while the VHF signal surrounds it. Lower frequencies, such as VHF, are more easily diffused around large smooth obstacles and can travel more easily from bricks and stone.
For most applications, lower radio frequencies are better than longer distances. This is illustrated by the television broadcast station. A typical VHF station is approx. It operates at 100,000 watts and has a range of approximately 60 miles. An UHF station with a 60-mile coverage radius requires 3,000,000 watts of data transmission.
So there is no clear choice, which is better for VHF or UHF. There are plenty of "black magic" in radio technology, so it's not always easy to tell which one will work better for the application. Below you will find a more detailed description of the most appropriate technology for you.
The UHF device operates between frequencies between 300 MHz and 3000 MHz. Until recently, it was not widely used. Now UHF radio frequencies are used for GPS, Bluetooth, cordless phones and WiFi.
There are several available channels with the UHF, so in more populated areas UHF is less likely to cause interference with other systems. If you are in an area where the population is thin, the VHF must work well. Not long ago, the FCC also opened a new VHF frequency called MURS, which has not been used in most areas. In the VHF section, read more about MURS. If you are in an area where interference from other radios can be a problem, UHF transmitters and receivers may be the best choice unless you are using a MURS VHF radio. The UHF penetrates more physical obstacles than walls, buildings, and the spacious landscape. Anything that prevents radio waves weakens the radio signal. UHF reduces this effect. Although the UHF radio waves can not go far, the VHF is more likely to pass through the obstacles.
The differences between indoor distances are outlined below with a single lead from a leading two-way radio release of one line of manual VHF and UHF bi-directional radios:
"Coverage estimates: Full power angle, no obstacles in the range of about 4 + indoor coverage of the VHF at approximately 270,000 sq. ft. and 300,000 sq. UHF, we expect the 20-level vertical coverage on VHF and 30 floors at UHF Note: Range and Coverage Estimates are Not Guaranteed. "
VHF waves are not very good for walls, buildings, and ugly landscapes. Therefore, in these areas, VHF radios significantly reduce range. This is not necessarily a problem if the required range is only a few hundred feet. You can also add an external antenna to an indoor VHF base station that reduces or eliminates this problem.
One disadvantage of UHF is that the FCC requires that it be licensed to operate these frequencies. Although many frequencies of the VHF business are also required. If you select a radio on VHF MURS frequencies, you can operate it without a license. UHF equipment is generally more expensive. The components need to be fine tuned and costly to the construction. This does not mean that it is necessarily better, but more expensive.  One of the advantages of UHF Transmission is the physically short wave generated by the high frequency. This means that the radio antenna may be shorter than an equivalent VHF radio. VHF radio
VHF device operates between 30 MHz and 300 MHz frequencies. FM radio, bi-directional radios, and television programs work in this range.
Both UHF and VHF radios tend to look, but VHF is slightly more. Waves produce trees and tight landscapes, but are not like UHF frequencies. However, if a VHF wave and an UHF wave were passed over a barrier-free area, the VHF wave would almost double as far as it could be. This facilitates the transfer of VHF in the long run. If you are mainly outdoors, VHF radio is probably the best choice, especially when using a base station radio and adding an external antenna.
As VHF takes longer and is not so complicated, equipment is generally cheaper than similar UHFs. One disadvantage of this equipment may be its size. Because the frequency waves are larger, the antenna must be larger.
VHF radios have less available frequency as well. There is a higher probability that interference with radios may be a problem. However, the FCC has recently caused this problem when it opened the MURS frequencies. The frequency of 150 MHz is a Citizens Band radio spectrum called a MURS service. MURS Multi-Use Radio Service. This service can be used in the United States and Canada. This is a low power, short-range service for the VHF 150 MHz Citizens Band radio spectrum. The MURS frequencies have 5 channels, each containing 38 privacy codes that allow you to only record conversations about the code. The FCC does not require the use of MURS products for licensed users
You can use MURS to add a larger or an external antenna to improve the range. If you want to place an antenna on top of your house or business, you can do this with MURS. Some antennas claim that an external antenna can increase the transmitter's actual radiation power by a factor of 4. These MURS intercoms can send up to four miles and maybe even an external antenna, depending on the terrain
. VHF radios are that the battery life is almost always better than that of similar UHF units. For handheld radios this is extra.
VHF devices are generally cheaper for budget. Equipment may be more economical than similar UHF products.
In summary, planning to use bi-directional radios mainly within buildings, UHF is probably the best solution for you. If you use the two-way radio for external communication, then VHF is a good choice. Or radio technology can work for you if you do not actually have a long range on board. In this case, it is worth choosing the VHF because it is at a lower cost.
Source by sbobet