SPREAD- SPECTRUM TECHNOLOGY
In a Spread spectrum technology transmission is done over a
range of frequencies and makes use of low power.
TYPES OF SPREAD- SPECTRUM TECHNOLOGY
(1) Frequency hopping spread spectrum (FHSS)
(2) Direct sequence spread spectrum (FHSS)
Frequency hopping spread spectrum (FHSS): The technology hops from one
frequency to another during operation. The reason for hopping from frequency to
frequency is for security purpose. FHSS devices have 74 channels.
Dwell time: this is the duration allowed to stay on a particular channel.
Hopping time: this is the time it takes to hop from one particular frequency
to another
Direct sequence spread
spectrum (DSSS): the technology spread the messages over the range of
frequencies. It does not hop like the FHSS, Bluetooth devices make use of this
technology. DSSS transmits with the chipping code that helps the data overcomes
interference. Two pattern of chipping codes are generated depend. Transmitting
and receiving is done in bulk and does errors checking during transmission.
These are 14 channels in DSSS devices.