The advancing tech of cordless telephones
A cordless telephone is a portable telephone with a wireless handset. Unlike a standard, landline telephone, a cordless telephone needs household electricity to power the base station. The cordless telephone communicates with a base station connected to a fixed telephone landline via radio waves. This telephone can only be operated close to (usually approximately 100 meters) its base station, such as in and around the house. The cordless telephone is powered by a battery, which is recharged by the base station when the handset is not in use.
As for cordless telephone technology, most of its standards, like PHS (Personal Handy Phone System) or DECT (Digital Enhanced Cordless Telecommunications), have blended the once clear-cut line between cordless and mobile telephones by supporting cell handover, various advanced features like data transfer and even, to a certain degree, international roaming. Base stations are maintained by a commercial mobile network operator and users subscribe to the service in these deployment models.
In the U. S., seven frequency bands have been allocated by the FCC (Federal Communications Commission) for uses that include cordless telephones. However, practically all telephones in the U.S. use the 900 MHZ, 2.4 GHz or 5.8 GHz bands. The popular DECT telephone uses the 1.9 GHz from Europe.
Although communication companies usually advertise that higher frequency systems will improve audio quality and range, the reality of cordless telephone technology is that higher frequencies actually have worse propagation in the ideal case and path loss, the mechanization undergone by an electromagnetic wave in transit from a transmitter to a receiver in a telecommunication system. Signal strength, antenna quality and the method of modulation used are other factors that determine quality and range in cordless telephone technology.
Most manufacturers claim a range of about 100ft for their 2.4 GHz and 5.8 GHz systems. Unfortunately, inexpensive models fall short of this claim.
Nevertheless, there are a few advantages of moving into higher frequency. The 900 MHz and 2.4 GHz band are increasingly being used for a host of other devices including baby monitor, microwave oven, Bluetooth, wireless LAN. It is likely that the cordless telephone will suffer interference from signals broadcast by those devices. Cordless telephone technology may be advanced, but it’s not without its flaws.
Marylou Veith is a business advisor with PMC Telecom, a premier supplier of cordless phones in the UK |
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