|There are two major benefits of a wireless
intercom system over a traditional wired intercom. The first is
that installation is much easier since no wires have to be run
between intercom units. The second is that you can easily move the
units any time.
With a wireless intercom system, you can be up
and running minutes after you take them out of the box and power
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, 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
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 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
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. Now some 900MHz products use
digital spread spectrum which divides digital transmission across a
range of frequencies so other devices canít eavesdrop on your
conversations. Spread spectrum also enables multiple channels of
communication at the same time with the same network of intercoms.
The IntercomsOnline.com WireFree intercom is a
intercom system. The WireFree
wireless intercom system even creates a private network when you
first set up your intercoms so other devices cannot listen to your
conversations. Even other units of the same brand cannot listen to
your conversations unless they are taught the same security code
that your wireless intercoms use (that can only be done by having
access to one of your units).
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 WiFi 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 donít experience any problems in mixing 2.4GHz systems.
As an example, one of the problems users have
experienced is their WiFi 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.
Now 5.8GHz products are starting to make their
appearance. So far, about the only product available in this
frequency range are cordless phones. There are no known wireless
intercoms in this frequency. 5.8GHz devices are totally
compatible with 2.4GHz and other frequencies so no problems should
be experienced in mixing these.
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
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
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
Mile Range Intercom uses the MURS frequency.
While MURS cannot 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 houseís 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 theyíre 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
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.
We choose to not offer these power line systems at
IntercomsOnline.com due to their high return rate.
Choose a System For You
So finding the right
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
To see the high-quality wireless intercom systems offered by
IntercomsOnline.com, click here:
Author: David Onslow