The document discusses cordless telephones, explaining that they use radio waves to communicate between a base station connected to a landline and a portable handset. It describes how cordless phones work by converting calls to radio signals at the base and back to audio at the handset, and covers factors that influence their range like frequency band and channels. Security aspects are also covered, such as standards for different frequency ranges and how wiretapping of cordless telephone signals can be performed.

1. Cordless telephone
Veronika Khyzhniak
HKSY, 2017

2. Cordless telephone
A cordless telephone is a portable telephone that uses radio waves, rather than a wire, to
communicate with a base station that is connected to a standard landline.

3. How Does it work?
The base receives the incoming call, converts
it to an FM radio signal and then broadcasts
that signal.
The handset receives the radio signal,
converts it to an electrical signal and sends
that signal to the speaker.

4. 43-50 MHz
Because of the low frequency, these phones have short ranges and
poorer sound quality.
900 MHz
The higher frequency gives it a greater range and better sound quality.
2.4 GHz or 5.8 GHz
Can operate over a greater distance and it is more secure than lower frequency
models.
frequency

5. 10 to 25
channels
• 43-50 MHz
phones, some
inexpensive
900 MHz
phones
20 to 60
channels
• most 900 MHz
phones
50 to 100
channels
• high-end 900
MHz and
2.4/5.8 GHz
phones
channels

6. Standards (CT0)
2oo meters
31 and 39 MHz frequency bands
8 channels
One pair of frequencies during
each connection

7. Standards (CT1 and ct2)
CT1
40 channels
Frequency – 914-915 MHz
CT2
40 channels
Frequency – 864.1 MHz – 868.1MHz

8. Digital Enhanced CordlessTechnology
dect
Low Cost
Low radiation
Recharging
Security
High Quality

9. Security
How wiretapping works: