When deciding to add a new wireless intercom system to your ever-growing portfolio of wireless devices in your home or business, first think about compatibility with products you already own (or have your close neighbors own). You also need to consider the scope and features you need.
Wireless intercom frequencies
There are several frequency ranges in the United States for unlicensed consumer wireless products. These are the 49 MHz, 900 MHz, 2.4 GHz, 5.8 GHz and Family Radio Service (FRS) bands. Recently, the FCC added the Multi-Use Radio (MURS) service. The radio frequencies for the devices are similar in Canada, but MURS cannot be used there.
When consumer wireless products were first introduced, these wireless products used the 49 MHz frequency band. The early cordless phones used this spectrum and are still used by low-cost baby monitors and other low-cost wireless devices. It has a short range and is prone to high interference. You probably won’t find any wireless intercom systems that use this spectrum anymore, and if you do, you won’t want them.
Later, 900 MHz products using analog transmission technology appeared on the market. Neither the 49 MHz products nor the early 900 MHz products have any form of security. Anyone with a device operating on the same frequency can eavesdrop on conversations. Newer products with 900 MHz digital spread spectrum divide the digital transmission into a frequency range so that other devices cannot eavesdrop on your conversations. Broad-spectrum digital intercoms also have a greater range than analog 900 MHz units. There are currently at least two wireless intercoms on the market, but only one uses digital spread spectrum. A wireless intercom system that uses spread spectrum can communicate up to 1000 feet.
The 2.4 GHz devices were next on the market. More and more cordless phones and other devices appear in this assortment. When it comes to intercom systems, the main users of this range are video intercom systems, although the only wireless video intercom on the market has recently been discontinued. 2.4 GHz is also the frequency range used by Wi-Fi wireless data networks (802.11B / G) in homes and businesses, so products in this range can interfere with each other.
Family Radio Service (462-467 MHz) operates on the Ultra High Frequency (UHF) band and is essentially an upgrade to the old walkie-talkies. These portable two-way radios are sold everywhere and heavily used, so any intercom system in the range would have to compete with these portable two-way radios (and anyone can eavesdrop on your conversations). There are no known wireless intercom systems using FRS.
Now, 5.8 GHz products are starting to appear in the cordless phone arena. There are no compatibility issues between the 5.8GHz and 2.4GHz devices, so there should be no problems with mixing them. However, there are currently no known wireless intercom systems in this regard.
You’ll also see some intercom systems that claim to be wireless, but actually use your home or business power cabling to send and receive transmissions from the intercom. They are often referred to as “wireless FM intercoms” even though they often transmit them over AM home wiring. To use them, you just need to plug the AC adapter to the wall. These systems are very prone to hum or buzzing and are not recommended unless you are prepared for the possibility. Since your home wiring is 240 volts and is split into two phases of 120 each, you may also experience problems with the signal trying to cross the phases. One part of your home or business may work well while the other half may not. These intercoms are usually the cheapest intercoms in this group.
Long-range wireless intercoms
The latest addition to the wireless intercom market are products in the MURS frequency range. MURS is a service in the VHF (Very High Frequency) 150 MHz radio band. MURS has four times the power increase than the FRS radio. And unlike FRS, you can add a larger or external antenna to improve coverage. If you want to put the antenna on the roof of your house, you can do it with MURS. Some antenna manufacturers claim that an external antenna can increase the effective radiant power of a transmitter by a factor of 4. These MURS intercoms can transmit up to four miles and maybe even more with an external antenna.
The Federal Communications Commission (FCC) in the United States does not require a license to use MURS frequencies, so you won’t have to go through the process.
There are 5 MURS channels and 38 noise eliminators or “silent codes” that can be used on each of these channels. These quiet codes keep the radios quiet, unless another radio is programmed on the same channel and quiet code. Chances are you won’t have to worry about these cheats as using MURS is very light. There are only a few MURS radio manufacturers, so traffic on these frequencies is difficult to find in most areas.
The MURS Intercom system is a wireless intercom that you need if you have a large property or need to talk between buildings. Using MURS you can communicate not only at home, but also with neighboring houses. You can even add a portable device to the MURS intercom system to stay connected while away from home.
Wireless outdoor long-range intercoms
You can also get a commercial grade wireless call boxes that communicate with base station radios and intercoms. These wireless callboxes are waterproof and designed for outdoor use. They can open gates or doors remotely if you have a gate relay model. Callboxes are also available in vandal-proof housings with stainless steel front panels. The range on them is up to a mile or more if you use an external antenna. These wireless call boxes can be battery powered, via an AC-DC converter, or solar powered. Callboxes are available in UHF and VHF frequencies, so you can match them with existing radios if you have them. You can get callboxes that operate on unlicensed MURS frequencies, so you can use them with MURS intercoms or radios.
The benefit of a wireless call box is that you save money as you don’t have to excavate and run an expensive cable to the device. You also don’t have to pay any airtime or telephone service charges with these wireless systems. Another advantage is that because the device is wireless, people monitoring the device can wear portable two-way radios that communicate with the call box. This allows the monitors to be mobile.
Wireless intercom functions
Another thing to consider is what features you need for your specific application. Commercial applications often require a greater variety of functions. For example, the MURS wireless system offers a wide range of products that can be used with it. Not only can you get military grade radios with multiple headset options, you can also get base station intercoms, wireless solar powered call boxes, wireless public address systems, customer service call boxes, wireless remote switches, and motion detection devices. For less commercial or residential applications, the 900 MHz intercom system has outdoor intercoms and doorbell intercoms that can be used with indoor intercoms.
So choosing a wireless intercom depends on the app you have, the wireless devices already in your home or business, the range you need to cover, and your budget. However, once you have chosen the right system, you will be able to enjoy the convenience of a wireless intercom system for many years to come.