If the cordless telephone is not a miracle then what is? One can move about with it all over the house without breaking the conversation or getting entangled in wires. Cordless phones have the basic features of the normal telephone and there are many models available.
Basically the cordless phone is an amalgam of the telephone and the radio (transmitter as well as receiver). The cordless phone comprises of two things - the base and the handset. The base is attached to the main phone connection with the help of a jack. It accepts the calls coming in through the line of the phone and then converts it into a FM radio signal. After having done so, it transmits that signal.
The handset gets this radio message from the base and changes it to an electric signal. The latter is then converted to sound and eureka! One can hear! While talking, the handset sends the voice through a second FM radio signal back to the base. The latter receives it, changes it to an electrical signal and then transmits the signal through the lines to the other person at the other end of the line. Thus the base and the handset work on a pair of frequencies that allow for talking and listening at the same time. It is technically known as duplex frequency.
Cordless phones made its first entry in 1980 but their range was limited, sound quality was poor because walls and other objects acted as obstructions. There was little security as the signals could easily be intercepted. In 1986 with the granting of a higher frequency range by the relevant authorities the interference problem of the cordless phones decreased and the amount of power required to run these also lessened. But nevertheless the range was limited and the sound quality remained poor. With the further increase of frequency to 900 MHz in 1990 the sound reception improved, became clearer and longer distances came to be covered with a choice of channels. But the price remained beyond the reach of the common man.
In 1994 digital phones came to be introduced. It made conversations less exposed to eavesdropping. In the following year further advancement in technology in the form of digital spread spectrum was introduced in cordless phones and in this way the march of technology continued to make the cordless phone into a marvel and miracle with greater range, security and clarity of sound.
The cordless phone being a combination of the ordinary telephone and the radio has certain distinctive features that the general phone does not have. It relates to range, sound quality and security. By range is meant the distance that the handset is kept away from the base. This range can affect the quality of the sound being obstructed by walls and other like items.
Security is a big problem because the radio signals from both the handset and the receiver travel across open air paths where they can be easily picked up by other instruments like similar cordless phones, radio scanners or baby monitors.
Connected with the performance of the cordless phones are radio frequency, analog in comparison with digital technology and the number of the channels. The cordless phones works on many radio frequencies. Analog technology is mostly used in cordless phones in the cheaper models. It is more noisy and less secure. The sophisticated latest models use digital technology. All cordless phones have rechargeable batteries.
The invasion of cell phones however has taken away much of the focus on cordless phones although it still retains its market position.
