With a wireless intercom system, you can be up and running minutes after you take them out of the box and power them up.
But with that ease of installation and convenience also comes some risk. There is risk of interference from other wireless and electrical devices. Other wireless devices near the intercom such as cordless telephones, wireless data networks, and remote audio speakers can interfere. Electrical devices such as motors can also cause noise on some systems.
There is also risk of other people hearing your conversations by picking up your conversation on a scanner, baby monitor, cordless phone, or a similar device on the same frequency. However, there are wireless intercoms that reduce or eliminate both of these risks.
The United States and Canada have several frequency ranges for wireless intercom systems and other wireless products. They are 49MHz, FM band (200KH - 270KHz), 900MHz, 1.6GHz, 2.4GHz, 5.8GHz, and in the U.S. only, the MURS (150 MHz). There are also Power Line Carrier units that communicate over house wiring that are referred to as wireless intercoms.
The newest edition to the world of wireless intercoms are WI-FI intercoms. These aren't used in the traditional sense of wireless intercoms where you have two devices in the same building and communicate between them. Traditional radio frequency units still fit that need. Instead they are used more for door or gate intercoms. The intercom at the door or gate uses Wi-Fi signals to communicate back to the house or commercial building. The the signal from the gate goes through the Internet to a smartphone or tablet PC. That way you can be anywhere and talk to visitors at the door or gate. They also have video capabilities so you can see who is there.
The 49MHz frequency was used by early cordless telephones and is still used by baby monitors and other low-end wireless products. Its range is short and conversations are not secure. It is also the most likely frequency to pick up noise from electrical devices. There are no known wireless intercom systems that still use this band.
FM band (200KH - 270KHz)
You will find intercom systems that use the FM frequency. They may work well for you and they may not. It depends on what other transmitting and electrical devices are nearby. They are also more prone to electrical interference. They are also not secure so anyone can listen to your conversations. If you look at the feedback on the Internet, a large percentage of those who purchase an FM wireless intercoms are are not happy with them. You'll still find many of these intercoms on the market.
900 MHz products were next to market. The 900 MHz radio frequency band is used only in North America, Australia, and Israel. When these products first came to market they communicated using analog technology. One problem with analog 900MHz products is that they allowed other people to hear your conversations if they had a device that is using the same frequency. Then 900MHz products used digital spread spectrum which divided digital transmission across a range of frequencies so other devices can't eavesdrop on conversations. Spread spectrum also enables multiple channels of communication at the same time with the same network of intercoms. The biggest seller of these stopped selling them so not sure you can get any intercoms in this frequency anymore.
After 900MHz came 2.4GHz frequency devices. 2.4GHz is used worldwide (Including in North America, Australia, and Israel). There aren't too many wireless intercoms available in this range except for video intercom systems.
But one of the problems with 2.4GHz wireless devices is that this is the frequency range used by Wi-Fi wireless data networks (802.11B/G) in residential and business.
If you have a wireless connection to the Internet or other PCs in your house or business, this network could interfere with your wireless intercom system. However, the majority of people do not experience any problems in mixing 2.4GHz systems.
As an example, one of the problems users have experienced is their Wi-Fi network resets every time they use their wireless intercom, which then causes the intercom to reset. Or they simply hear clicking noise on their intercom system.
If you do experience interference, the setup for the wireless data routers allows you to select the wireless channels the router uses to communicate. So if you experience problems you could try changing the channels.
But the problem with this is that many 2.4GHz devices use spread spectrum technology. That means they are changing frequency every second or less. They often use the entire 2.4GHz spectrum allocated to these products so changing the frequency on your wireless network will do no good. If you use a wireless network in your house and you choose a video intercom that uses this frequency, make sure there is a return policy that lets you test the unit and return it if you experience interference.
5.8GHz products made their appearance, but the only products available in this frequency range are cordless phones. There are no known wireless intercoms in this frequency. 5.8GHz devices can be used in conjunction with 2.4GHz and other frequencies so no problems should be experienced in mixing these.
DECT 6.0 is the latest and it uses the 1.9GHz range in North America. They work more like a cordless telephone and, in fact, they use the same DECT 6.0 technology, which is encrypted so your neighbors will not be able to listen in. In the past, wireless intercoms worked more like walkie-talkie radios where one radio could talk at a time with push-to-talk and release-to-listen functionality. You can find at least one DECT intercom that has full handsfree capability. There are also multiple channels so you can call individual stations.
MURS - 150MHz
There are five frequencies in the 150 MHz radio spectrum that are called the MURS service. MURS stands for Multi-Use Radio Service. This is a newly created service for use in the United States. MURS is a short range (can be several miles) service that uses the VHF (Very High Frequency) radio spectrum.
The FCC does not require users of products for these bands to be licensed, but it does impose strict regulations on the types of products and services that may be supplied to consumers.
Previously the FCC came out with the Family Radio Service (FRS) in the 462 and 467 MHz spectrum in which you can find handheld units, but no intercom systems based on this service. MURS is similar to FRS but it has a power increase of four times that of FRS radio. And unlike FRS, you can add a larger or external antenna to improve range. If you want to put an antenna on top of your house, 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 radio intercoms can transmit up to four miles, and perhaps more with an external antenna. These units are not secure, but there are fewer systems in use and few devices outside of a scanner to intercept this frequency. The IntercomsOnline.com MURS 4 Mile Range Intercom uses the MURS frequency.
While MURS cannot legally be used in Canada, there are two frequencies at 151.055 and 151.115 MHz that are unlicensed frequencies in Canada. Many of our commercial intercoms are available in these frequencies for use in Canada. Please contact us if you have a need for these.
Power Line Carrier Systems
Power Line Carrier (PLC) intercom systems communicate using a very low FM frequency over your house's existing 110 volt AC house wiring that supplies power to receptacles and light fixtures. You just plug them in anywhere you have an outlet and they are ready to go. Technically they are not wireless, but they are sold that way.
While they sound like the ideal solution for basic applications, most users are typically not happy with these intercom systems.
These units are very susceptible to interference from both inside and outside the house or business. You may experience buzzing, poor audio, or they may work perfectly well for you. Or they may work well for you and then when you or your neighbor adds some new electrical device, they could quit working for you. You also could experience problems with units not being able to communicate because of the way your house wiring is done. The signal may not be able to cross to the second "phase" of your house wiring (220 Volts is run to each house and then split into two phases to give you 110 Volts). These intercoms are usually very inexpensive. These systems are not recommended for most people, but they are cheap.
Radio Shack was the last known provider of these intercoms in the US, but they are now discontinued.
So finding the right wireless intercom system for you really depends on your application and the wireless products you already have in your home or business. It also depends on the wireless products those around you are using. When it comes to using wireless products, there is no guarantee that you won't experience some type of interference, so look for a vendor who has a guaranteed return policy if the system you choose doesn't work for you. Then you really can't lose by trying a wireless intercom system.
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