( 
)A PDF version with pictures and applications is available at IntercomsOnline.com
Introduction
This book is about using two-way radios and other wireless devices for improving communication in your business. The results of this improved communication will vary, but depending on your application, they can include increased safety, improved productivity, better customer or employee satisfaction, increased profits, or other benefits.
With the increased penetration of cell phones, and cell phones with push to talk capability, the use of two-way radios has slowly declined over the past several years. However, since the 9/11 terrorist attacks, the shootings at high-schools and universities, and the major natural disasters such as hurricane Katrina in New Orleans, people have discovered that you can’t always depend on the cell phone network. The cell phone network may go down, but the airwaves will not.
There are other non-emergency situations where two-way radios just work better than cell phones too. This book will point those out and it will show you applications for these radios that you’ve never thought of. We will show you other products that work with two-way products that you likely didn’t know existed.
Types of Two Way Radios
Two-way radios are essentially available in three types: hand-held portable, vehicle-mounted mobile, and desktop base station. There are also unique two-way radio devices such as indoor and outdoor call boxes and one-way radio receivers for wireless paging that we will cover in other sections as well.
Handheld portable two-way radios are the walkie talkie type of radios you see people carrying around. As ruled by the FCC (Federal Communications Commission), handheld radios may not have more than 5 watts of power.
Vehicle-mounted mobile two-way radios mount in a car or truck and they use the vehicle’s battery for power. They may have their own antenna, but better range is achieved by using an externally-mounted antenna.
Desktop base station radios use wall AC power and they too may have a built-in antenna, but this antenna may be disconnected and then connected to cable that leads to an external-mounted antenna. The higher the antenna is mounted, the better the range. The vehicle-mounted mobile radios are usually used as base stations by just adding an AC to DC power converter.
Mobile and Base station radios are usually more powerful than hand-held radios and may have as much as 100 watts of power.
Understanding Radio Frequencies
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 better than the other. They each have their pluses and minuses. Both formats are effective ways to communicate with another person so deciding on the right radio for you depends on your application.
Two-way radios communicate with each other through use of radio waves. Radio waves have different frequencies, and by tuning a radio receiver to a specific frequency you can pick up a specific signal.
Radio waves are transmitted as a series of cycles, one after the other. You will always 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 relationship 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 number of cycles per second. Lower frequencies produce 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 significant about wavelength for two-way radios is that it affects transmission range under certain 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 penetrate sea water to a depth of approximately 20 meters. So a submarine at shallow depth can use these frequencies.
So from what you read above you may think VHF is always the better choice for a two-way radio no matter where you are using it. That’s not necessarily true. Even though VHF has better penetrating capabilities, that doesn’t necessarily make it the better choice for buildings. Remember the conversation about wavelength above? Wavelength has a big impact on transmission.
To explain this let’s assume we are communicating from one side of a commercial building 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 around five feet long. These are in the ballpark of their normal 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 several inches long. The mesh keeps the microwaves trapped in the oven but it allows you to see inside because light waves have a microscopic wavelength.
Just imagine walking through the building carrying a five foot wide pole. You will encounter the same challenges a VHF signal encounters. Now imagine walking through the building 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 penetrate through drywall, masonry, human bodies, furniture, wall paneling, and other solid objects. All these objects will reduce the signal strength though. The more dense the object, the more it reduces the signal. VHF will penetrate these obstacles better than UHF, but that doesn’t necessarily mean that VHF is better 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 around it. Lower frequencies such as VHF diffract around large smooth obstacles more easily, and they also travel more easily through brick and stone.
For most applications, lower radio frequencies are better for longer range. A broadcasting TV station illustrates this. A typical VHF station operates at about 100,000 watts and has a coverage radius range of about 60 miles. A UHF station with a 60-mile coverage radius requires transmitting at 3,000,000 watts.
So there is no clear choice for which is better, VHF or UHF. There is a lot of “black magic” to radio technology so it’s not always easy to tell which will work better for your application. To help you decide on the best technology for you, more detail about each one is included below.
UHF Radio
The UHF radio band for commercial radios is between 400 – 512 MHz. Until recently, it wasn’t widely used. Now, the UHF radio frequency is used for two-way radios, GPS, Bluetooth, cordless phones, and WiFi.
There are more available channels with UHF so in more populated areas UHF may be less likely to have interference from other systems. The range of UHF is also not as far as VHF under most conditions, but this reduced range may be a positive in some cases. Since UHF has lower range, there is less chance of distant radios interfering with your signal.
If you are in an area where population 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 choice unless you use a MURS VHF radio.
While VHF may be better at penetrating physical barriers like walls that doesn’t mean it will give you greater coverage in a building. The shorter wavelength of UHF means that it can find its way through more spaces in your building. In the walking around with a pole example above, the UHF signal has fewer obstacles that totally block it.
To highlight the differences in indoor range, below is an excerpt from a brochure of a leading two-way radio maker on the predicted 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 approximately 4+ miles. Indoor coverage at VHF is approximately 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.”
The greater wavelength of VHF makes it more difficult for it to bounce its way through walls, buildings and rugged landscape. Therefore range will be 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 station that will reduce or eliminate this problem.
One of the downsides to UHF is that the FCC requires you to get a license to operate in these frequencies, although many frequencies in the VHF business band also require a license. If you choose a radio in the VHF MURS frequencies you can operate it without a license.
One other advantage of the short wavelength that is produced by the higher UHF frequency is that the antenna on the radio can be shorter than an equivalent VHF radio. That can make it more convenient to carry around as a portable radio.
VHF Radio
The VHF radio band for commercial radios is between 130 – 174 MHz. FM radio, two-way radios, and television broadcasts operate in this range.
Both UHF and VHF radios are prone to line of sight factors, but VHF a little 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 almost 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 station radio indoors and you add the external antenna. The higher you can place the antenna, the further you can transmit and receive. One exception to using a VHF radio outdoors is if you are using it in a heavily wooded area. Under these conditions a UHF radio may be able to transmit better though the trees.
Since VHF has been around longer and isn’t as complicated to make, equipment can be cheaper when compared to similar UHF equipment. One disadvantage to this equipment can be its size. Since the frequency waves are bigger, an antenna must be bigger.
VHF radios also have a smaller number of available 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 service is for use in the United States and Canada. It is a low power, short range service 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 from radios transmitting your code. The FCC does not require users of products for MURS to be licensed.
With MURS you can add a larger or external antenna to improve range. If you want to put an antenna on top of your building or a tower, you can do it with MURS. Some antenna manufacturers claim an external antenna can increase the effective radiated power of a transmitter by a factor of 4. These MURS intercoms can transmit 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 almost always better than for similar UHF units. For handheld radios this is a plus.
In summary, if you are planning on using your two-way radios mainly inside buildings, then UHF is likely the best solution for you, but it in lots of applications VHF could still work fine. If you are mainly using your two-way radios for communication outside, then VHF would be a good choice, unless the area you are covering is heavily wooded. Either radio technology can work for you if you don’t really have a long range to cover. There are also repeaters you can install that relay a UHF signal. We’ll talk about those in the Accessories section.
Two-Way Radio Power
One of the most important factors in the distance a two-way radio will communicate is its power output. This power output is measured in “watts.” You’ve likely heard an FM radio station say they are broadcasting at 50,000 or 100,000 watts. Well, a handheld two-way radio usually broadcasts at 1-5 watts. A vehicle mobile radio may broadcast anywhere from 5 to 100 watts. The more watts a radio has, the farther it can transmit.
For battery-powered handheld radios more watts is not always a good thing. The higher the wattage, the quicker your batteries will run down. Fortunately, quality two-way radios have can set the transmit power of a selected channel frequency between HI and LOW power so you can decide when you need a power boost.
Two-Way Radio Range
If you go down to your local building supply or discount store you will see radios that say they have a range of 14 miles, 22 miles, or something like that. Yet when you take them home you find that they don’t even go a mile. Why is that?
One of the biggest factors to reducing range is the obstacles in the path of transmission. These obstacles absorb and reflect the radio waves so while a radio advertised to go 22 miles may actually do that if both users are standing on peaks of a mountain with nothing in between, the same radio can’t go a half mile through a forest. Two-way radios communicate “line of sight,” which means that if you can see between two points, the radio should be able to communicate between these two points. Consider that the radio the Apollo astronauts on the moon used to communicate only used one watt of power and you’ll get the picture on this.
If you consider that two points on land or water become invisible after about five miles between them because of the curvature of the Earth, you can understand that communicating more than five miles becomes difficult even if there are no obstacles between the radios. The key to getting more range is either to raise the height of the antenna, increase the power of the radio, or both.
Two-Way Radio Antennas
The good thing about base station intercoms/two-way radios is that they allow you to extend range by using an external antenna. The base station units have what's called a BNC connector that enables you to twist off the antenna that comes with the radio and then twist on a new antenna connected to a cable.
You will get noticeably better results and more range with your radios with an external antenna, especially if you can place it high. It is the single most important factor in increasing transmitting and receiving range of a radio. You'll need to make sure you choose an antenna that is specifically designed for the frequencies and application you are using and then choose the best location possible to install it.
For MURS radios, the FCC limits antenna height to 20 feet above a structure (exclusive of the tower, mast or pole on which it is mounted), or 60 feet above ground (whichever is greater). The higher you place your antenna, the greater range you will get. If you mount an antenna on your vehicle and connect it to your mobile MURS two-way radio, the higher you place the antenna on your vehicle, the greater range you'll get.
If you are using a handheld radio and walking around with it, you can't very well use an external antenna. You may be able to extend range by installing a better antenna than the one that came with the radio, but keep in mind that the antenna that came with the radio is "tuned" specifically for that radio. If you put on an antenna that isn't properly tuned, you could lower range.
Channel Usage
Two-way radios can have multiple channels. In some cases like the MURS radios, there are only 5 channels available. Other radios typically have up to 10 channels available, or you can program them to only use one channel.
One thing about a two-way radio is that when you press the Talk button and speak, everyone on that channel will hear you. If you have individual departments in your business that you want to separate, then this isn’t the ideal solution.
That’s where you can use the multiple channels on the radio. If you are in a manufacturing environment for instance, you could set up Channel 2 for Shipping, Channel 3 for the Office, Channel 4 for Manufacturing, and so on.
You can use the channels sort of like an intercom system that lets call individual people or groups instead of broadcasting a message to everyone. So the Shipping people keep their radios on Channel 2, but if they need to talk to people in the office, they change to Channel 3.
Some handheld radios also have a scanning capability that also works well for this type of application. You can actually program the channels you want to scan, and the radio will only pick up conversations for the channels you have programmed.
In the example above say you add a Channel 1 as the Broadcast, Paging, or All Call channel. Now you set each radio to scan not only their department channel, but also the Paging channel as well. So if there is need to broadcast a message then anyone can change to Channel 1 and everyone hears the message. This is a great emergency notification system.
FCC Licensing
If you are purchasing a radio for your business, most business-band radios require you to get a License from the FCC before you can use the radios. One exception to this is if you purchase radios that operate in the MURS frequencies.
IntercomsOnline.com sells radios in the MURS unlicensed 151.8200 to 154.6000 MURS VHF range, the licensed 151.6250 to 154.6550 VHF Business Band, and the licensed 461.0375 to 469.5625 UHF Business Band range.
Unfortunately the FCC is a government agency and off course that means that getting your FCC license can be a confusing and time-consuming thing. But, since there can be fines of $8,000 per day for unlicensed and/or improperly licensed use of a radio system, plus various other fines; it’s something you definitely want to do if you choose a licensed frequency.
Fortunately, you don’t have to get a license for each radio. The FCC licenses the radio user, not the radio itself. You can get a license for your company in a specific geographic area. An FCC coordinator will assign frequencies you can use for all of your radios for a period of 10 years.
If you don’t want to tackle getting a license by yourself, you can get help from organizations like Enterprise Wireless Alliance. They will do the process for you for a nominal fee.
If you choose to file for your own FCC license, you must first register through FCC CORES. After registration, you will be assigned a Federal Registration Number (FRN). This number uniquely identifies you in all transactions with the FCC. The use of a FRN is mandatory. If you have questions about this process, the FRN Help Desk Administrator phone number is (877) 480-3201. The FRN Help Desk staff are available from 8 a.m. to 6 p.m. Eastern Time.
After you have your FRN, then you use the Universal Licensing System (ULS) to complete your application. ULS allows you to use any PC with Internet access to research, manage, renew, and pay any applicable fees for your wireless licenses through a password-protected account. ULS frees you from having to fill out and mail a paper application, and it gives you secure, online access to your licenses and pending applications. More information about ULS can be found online at the following address: (no links allowed)
For other licensing questions, you can call the FCC Consumer Center at (888) 225-5322.
Feature Highlights
Below are some of the more noteworthy features available on two-way radios:
Vox
The Voice Activated Transmit (VOX) feature enables you to use your radio “hands free.” When VOX is turned on, the radio will automatically begin transmitting when you speak, without pressing the push-to-talk button. VOX works well for any application
On most VOX-capable radios there is a slight delay between when you start speaking and when the microphone turns on so the first part of the conversation may be clipped. Most radio users overcome this by repeating the first word.
Military Specification Standards
In an effort to achieve standardization objectives for purchases of products used by the military and other government organizations, the U.S. Department of Defense created standards that these products must meet. You will see these standards called military standard, “MIL-STD”, or “MIL-SPEC.” These standards ensure products meet certain requirements, commonality, reliability, compatibility, and similar defense-related objectives.
The Department of Defense also has standards for two-way radios and radios that meet this standard must meet levels for such criteria as vibration, rain, salt air, sand/dust, shock (dropping), humidity, temperature as well as other factors.
Buying a product that meets mil-spec standards means you are buying a quality product that is built to withstand tougher use.
You may also see radios with an “IP” designation. IP stands for Ingress Protection and it is an international standard that specifies the sealing effectiveness of the enclosure of a product. It is a two digit code that tell you how effective the enclosure is to penetration from fingers, dust, and moisture.
For instance, for a radio that meets IP 55, the first 5 means it is protected from the amount of dust that would interfere with its operation. The second 5 means that it is protected from water that shoots from a nozzle.
Introduction
This book is about using two-way radios and other wireless devices for improving communication in your business. The results of this improved communication will vary, but depending on your application, they can include increased safety, improved productivity, better customer or employee satisfaction, increased profits, or other benefits.
With the increased penetration of cell phones, and cell phones with push to talk capability, the use of two-way radios has slowly declined over the past several years. However, since the 9/11 terrorist attacks, the shootings at high-schools and universities, and the major natural disasters such as hurricane Katrina in New Orleans, people have discovered that you can’t always depend on the cell phone network. The cell phone network may go down, but the airwaves will not.
There are other non-emergency situations where two-way radios just work better than cell phones too. This book will point those out and it will show you applications for these radios that you’ve never thought of. We will show you other products that work with two-way products that you likely didn’t know existed.
Types of Two Way Radios
Two-way radios are essentially available in three types: hand-held portable, vehicle-mounted mobile, and desktop base station. There are also unique two-way radio devices such as indoor and outdoor call boxes and one-way radio receivers for wireless paging that we will cover in other sections as well.
Handheld portable two-way radios are the walkie talkie type of radios you see people carrying around. As ruled by the FCC (Federal Communications Commission), handheld radios may not have more than 5 watts of power.
Vehicle-mounted mobile two-way radios mount in a car or truck and they use the vehicle’s battery for power. They may have their own antenna, but better range is achieved by using an externally-mounted antenna.
Desktop base station radios use wall AC power and they too may have a built-in antenna, but this antenna may be disconnected and then connected to cable that leads to an external-mounted antenna. The higher the antenna is mounted, the better the range. The vehicle-mounted mobile radios are usually used as base stations by just adding an AC to DC power converter.
Mobile and Base station radios are usually more powerful than hand-held radios and may have as much as 100 watts of power.
Understanding Radio Frequencies
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 better than the other. They each have their pluses and minuses. Both formats are effective ways to communicate with another person so deciding on the right radio for you depends on your application.
Two-way radios communicate with each other through use of radio waves. Radio waves have different frequencies, and by tuning a radio receiver to a specific frequency you can pick up a specific signal.
Radio waves are transmitted as a series of cycles, one after the other. You will always 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 relationship 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 number of cycles per second. Lower frequencies produce 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 significant about wavelength for two-way radios is that it affects transmission range under certain 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 penetrate sea water to a depth of approximately 20 meters. So a submarine at shallow depth can use these frequencies.
So from what you read above you may think VHF is always the better choice for a two-way radio no matter where you are using it. That’s not necessarily true. Even though VHF has better penetrating capabilities, that doesn’t necessarily make it the better choice for buildings. Remember the conversation about wavelength above? Wavelength has a big impact on transmission.
To explain this let’s assume we are communicating from one side of a commercial building 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 around five feet long. These are in the ballpark of their normal 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 several inches long. The mesh keeps the microwaves trapped in the oven but it allows you to see inside because light waves have a microscopic wavelength.
Just imagine walking through the building carrying a five foot wide pole. You will encounter the same challenges a VHF signal encounters. Now imagine walking through the building 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 penetrate through drywall, masonry, human bodies, furniture, wall paneling, and other solid objects. All these objects will reduce the signal strength though. The more dense the object, the more it reduces the signal. VHF will penetrate these obstacles better than UHF, but that doesn’t necessarily mean that VHF is better 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 around it. Lower frequencies such as VHF diffract around large smooth obstacles more easily, and they also travel more easily through brick and stone.
For most applications, lower radio frequencies are better for longer range. A broadcasting TV station illustrates this. A typical VHF station operates at about 100,000 watts and has a coverage radius range of about 60 miles. A UHF station with a 60-mile coverage radius requires transmitting at 3,000,000 watts.
So there is no clear choice for which is better, VHF or UHF. There is a lot of “black magic” to radio technology so it’s not always easy to tell which will work better for your application. To help you decide on the best technology for you, more detail about each one is included below.
UHF Radio
The UHF radio band for commercial radios is between 400 – 512 MHz. Until recently, it wasn’t widely used. Now, the UHF radio frequency is used for two-way radios, GPS, Bluetooth, cordless phones, and WiFi.
There are more available channels with UHF so in more populated areas UHF may be less likely to have interference from other systems. The range of UHF is also not as far as VHF under most conditions, but this reduced range may be a positive in some cases. Since UHF has lower range, there is less chance of distant radios interfering with your signal.
If you are in an area where population 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 choice unless you use a MURS VHF radio.
While VHF may be better at penetrating physical barriers like walls that doesn’t mean it will give you greater coverage in a building. The shorter wavelength of UHF means that it can find its way through more spaces in your building. In the walking around with a pole example above, the UHF signal has fewer obstacles that totally block it.
To highlight the differences in indoor range, below is an excerpt from a brochure of a leading two-way radio maker on the predicted 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 approximately 4+ miles. Indoor coverage at VHF is approximately 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.”
The greater wavelength of VHF makes it more difficult for it to bounce its way through walls, buildings and rugged landscape. Therefore range will be 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 station that will reduce or eliminate this problem.
One of the downsides to UHF is that the FCC requires you to get a license to operate in these frequencies, although many frequencies in the VHF business band also require a license. If you choose a radio in the VHF MURS frequencies you can operate it without a license.
One other advantage of the short wavelength that is produced by the higher UHF frequency is that the antenna on the radio can be shorter than an equivalent VHF radio. That can make it more convenient to carry around as a portable radio.
VHF Radio
The VHF radio band for commercial radios is between 130 – 174 MHz. FM radio, two-way radios, and television broadcasts operate in this range.
Both UHF and VHF radios are prone to line of sight factors, but VHF a little 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 almost 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 station radio indoors and you add the external antenna. The higher you can place the antenna, the further you can transmit and receive. One exception to using a VHF radio outdoors is if you are using it in a heavily wooded area. Under these conditions a UHF radio may be able to transmit better though the trees.
Since VHF has been around longer and isn’t as complicated to make, equipment can be cheaper when compared to similar UHF equipment. One disadvantage to this equipment can be its size. Since the frequency waves are bigger, an antenna must be bigger.
VHF radios also have a smaller number of available 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 service is for use in the United States and Canada. It is a low power, short range service 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 from radios transmitting your code. The FCC does not require users of products for MURS to be licensed.
With MURS you can add a larger or external antenna to improve range. If you want to put an antenna on top of your building or a tower, you can do it with MURS. Some antenna manufacturers claim an external antenna can increase the effective radiated power of a transmitter by a factor of 4. These MURS intercoms can transmit 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 almost always better than for similar UHF units. For handheld radios this is a plus.
In summary, if you are planning on using your two-way radios mainly inside buildings, then UHF is likely the best solution for you, but it in lots of applications VHF could still work fine. If you are mainly using your two-way radios for communication outside, then VHF would be a good choice, unless the area you are covering is heavily wooded. Either radio technology can work for you if you don’t really have a long range to cover. There are also repeaters you can install that relay a UHF signal. We’ll talk about those in the Accessories section.
Two-Way Radio Power
One of the most important factors in the distance a two-way radio will communicate is its power output. This power output is measured in “watts.” You’ve likely heard an FM radio station say they are broadcasting at 50,000 or 100,000 watts. Well, a handheld two-way radio usually broadcasts at 1-5 watts. A vehicle mobile radio may broadcast anywhere from 5 to 100 watts. The more watts a radio has, the farther it can transmit.
For battery-powered handheld radios more watts is not always a good thing. The higher the wattage, the quicker your batteries will run down. Fortunately, quality two-way radios have can set the transmit power of a selected channel frequency between HI and LOW power so you can decide when you need a power boost.
Two-Way Radio Range
If you go down to your local building supply or discount store you will see radios that say they have a range of 14 miles, 22 miles, or something like that. Yet when you take them home you find that they don’t even go a mile. Why is that?
One of the biggest factors to reducing range is the obstacles in the path of transmission. These obstacles absorb and reflect the radio waves so while a radio advertised to go 22 miles may actually do that if both users are standing on peaks of a mountain with nothing in between, the same radio can’t go a half mile through a forest. Two-way radios communicate “line of sight,” which means that if you can see between two points, the radio should be able to communicate between these two points. Consider that the radio the Apollo astronauts on the moon used to communicate only used one watt of power and you’ll get the picture on this.
If you consider that two points on land or water become invisible after about five miles between them because of the curvature of the Earth, you can understand that communicating more than five miles becomes difficult even if there are no obstacles between the radios. The key to getting more range is either to raise the height of the antenna, increase the power of the radio, or both.
Two-Way Radio Antennas
The good thing about base station intercoms/two-way radios is that they allow you to extend range by using an external antenna. The base station units have what's called a BNC connector that enables you to twist off the antenna that comes with the radio and then twist on a new antenna connected to a cable.
You will get noticeably better results and more range with your radios with an external antenna, especially if you can place it high. It is the single most important factor in increasing transmitting and receiving range of a radio. You'll need to make sure you choose an antenna that is specifically designed for the frequencies and application you are using and then choose the best location possible to install it.
For MURS radios, the FCC limits antenna height to 20 feet above a structure (exclusive of the tower, mast or pole on which it is mounted), or 60 feet above ground (whichever is greater). The higher you place your antenna, the greater range you will get. If you mount an antenna on your vehicle and connect it to your mobile MURS two-way radio, the higher you place the antenna on your vehicle, the greater range you'll get.
If you are using a handheld radio and walking around with it, you can't very well use an external antenna. You may be able to extend range by installing a better antenna than the one that came with the radio, but keep in mind that the antenna that came with the radio is "tuned" specifically for that radio. If you put on an antenna that isn't properly tuned, you could lower range.
Channel Usage
Two-way radios can have multiple channels. In some cases like the MURS radios, there are only 5 channels available. Other radios typically have up to 10 channels available, or you can program them to only use one channel.
One thing about a two-way radio is that when you press the Talk button and speak, everyone on that channel will hear you. If you have individual departments in your business that you want to separate, then this isn’t the ideal solution.
That’s where you can use the multiple channels on the radio. If you are in a manufacturing environment for instance, you could set up Channel 2 for Shipping, Channel 3 for the Office, Channel 4 for Manufacturing, and so on.
You can use the channels sort of like an intercom system that lets call individual people or groups instead of broadcasting a message to everyone. So the Shipping people keep their radios on Channel 2, but if they need to talk to people in the office, they change to Channel 3.
Some handheld radios also have a scanning capability that also works well for this type of application. You can actually program the channels you want to scan, and the radio will only pick up conversations for the channels you have programmed.
In the example above say you add a Channel 1 as the Broadcast, Paging, or All Call channel. Now you set each radio to scan not only their department channel, but also the Paging channel as well. So if there is need to broadcast a message then anyone can change to Channel 1 and everyone hears the message. This is a great emergency notification system.
FCC Licensing
If you are purchasing a radio for your business, most business-band radios require you to get a License from the FCC before you can use the radios. One exception to this is if you purchase radios that operate in the MURS frequencies.
IntercomsOnline.com sells radios in the MURS unlicensed 151.8200 to 154.6000 MURS VHF range, the licensed 151.6250 to 154.6550 VHF Business Band, and the licensed 461.0375 to 469.5625 UHF Business Band range.
Unfortunately the FCC is a government agency and off course that means that getting your FCC license can be a confusing and time-consuming thing. But, since there can be fines of $8,000 per day for unlicensed and/or improperly licensed use of a radio system, plus various other fines; it’s something you definitely want to do if you choose a licensed frequency.
Fortunately, you don’t have to get a license for each radio. The FCC licenses the radio user, not the radio itself. You can get a license for your company in a specific geographic area. An FCC coordinator will assign frequencies you can use for all of your radios for a period of 10 years.
If you don’t want to tackle getting a license by yourself, you can get help from organizations like Enterprise Wireless Alliance. They will do the process for you for a nominal fee.
If you choose to file for your own FCC license, you must first register through FCC CORES. After registration, you will be assigned a Federal Registration Number (FRN). This number uniquely identifies you in all transactions with the FCC. The use of a FRN is mandatory. If you have questions about this process, the FRN Help Desk Administrator phone number is (877) 480-3201. The FRN Help Desk staff are available from 8 a.m. to 6 p.m. Eastern Time.
After you have your FRN, then you use the Universal Licensing System (ULS) to complete your application. ULS allows you to use any PC with Internet access to research, manage, renew, and pay any applicable fees for your wireless licenses through a password-protected account. ULS frees you from having to fill out and mail a paper application, and it gives you secure, online access to your licenses and pending applications. More information about ULS can be found online at the following address: (no links allowed)
For other licensing questions, you can call the FCC Consumer Center at (888) 225-5322.
Feature Highlights
Below are some of the more noteworthy features available on two-way radios:
Vox
The Voice Activated Transmit (VOX) feature enables you to use your radio “hands free.” When VOX is turned on, the radio will automatically begin transmitting when you speak, without pressing the push-to-talk button. VOX works well for any application
On most VOX-capable radios there is a slight delay between when you start speaking and when the microphone turns on so the first part of the conversation may be clipped. Most radio users overcome this by repeating the first word.
Military Specification Standards
In an effort to achieve standardization objectives for purchases of products used by the military and other government organizations, the U.S. Department of Defense created standards that these products must meet. You will see these standards called military standard, “MIL-STD”, or “MIL-SPEC.” These standards ensure products meet certain requirements, commonality, reliability, compatibility, and similar defense-related objectives.
The Department of Defense also has standards for two-way radios and radios that meet this standard must meet levels for such criteria as vibration, rain, salt air, sand/dust, shock (dropping), humidity, temperature as well as other factors.
Buying a product that meets mil-spec standards means you are buying a quality product that is built to withstand tougher use.
You may also see radios with an “IP” designation. IP stands for Ingress Protection and it is an international standard that specifies the sealing effectiveness of the enclosure of a product. It is a two digit code that tell you how effective the enclosure is to penetration from fingers, dust, and moisture.
For instance, for a radio that meets IP 55, the first 5 means it is protected from the amount of dust that would interfere with its operation. The second 5 means that it is protected from water that shoots from a nozzle.
Guide created: 09/26/08
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