Unformatted text preview: -28-AANSWERS TO NSWERS TO QQUESTIONSUESTIONS7.1The bandwidth is wider after the signal has been encoded using spread spectrum.7.2 (1) We can gain immunity from various kinds of noise and multipath distortion. (2)It can also be used for hiding and encrypting signals. Only a recipient who knowsthe spreading code can recover the encoded information.(3) Several users canindependently use the same higher bandwidth with very little interference, usingcode division multiple access (CDMA).7.3With frequency hopping spread spectrum (FHSS), the signal is broadcast over aseemingly random series of radio frequencies, hopping from frequency tofrequency at fixed intervals. A receiver, hopping between frequencies insynchronization with the transmitter, picks up the message.7.4Slow FHSS = multiple signal elements per hop; fast FHSS = multiple hops persignal element.7.5With direct sequence spread spectrum (DSSS), each bit in the original signal isrepresented by multiple bits in the transmitted signal, using a spreading code.represented by multiple bits in the transmitted signal, using a spreading code....
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- Fall '11
- Bit rate, SNR, Code division multiple access, Direct-sequence spread spectrum, Frequency-hopping spread spectrum