MULTIPLEXING AND SPEEDING
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This document discusses spread spectrum techniques, which combine signals from different sources into a larger bandwidth in order to prevent eavesdropping and jamming. It introduces two main spread spectrum techniques: Frequency Hopping Spread Spectrum (FHSS) which spreads signals by rapidly switching frequencies, and Direct Sequence Spread Spectrum (DSSS) which spreads signals by combining them with pseudorandom codes. The document contains diagrams illustrating how FHSS and DSSS work to spread signals across bandwidth.
MULTIPLEXING AND SPEEDING
- 1. 6.1 Chapter 6 Bandwidth Utilization: Multiplexing and Spreading Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 2. 6.2 6-1 SPREAD SPECTRUM6-1 SPREAD SPECTRUM In spread spectrum (SS), we combine signals fromIn spread spectrum (SS), we combine signals from different sources to fit into a larger bandwidth, but ourdifferent sources to fit into a larger bandwidth, but our goals are to prevent eavesdropping and jamming. Togoals are to prevent eavesdropping and jamming. To achieve these goals, spread spectrum techniques addachieve these goals, spread spectrum techniques add redundancy.redundancy. Frequency Hopping Spread Spectrum (FHSS) Direct Sequence Spread Spectrum (DSSS) Topics discussed in this section:Topics discussed in this section:
- 3. 6.3 Spread Spectrum A signal that occupies a bandwidth of B, is spread out to occupy a bandwidth of Bss All signals are spread to occupy the same bandwidth Bss Signals are spread with different codes so that they can be separated at the receivers. Signals can be spread in the frequency domain or in the time domain.
- 4. 6.4 Figure 6.27 Spread spectrum
- 5. 6.5 Figure 6.28 Frequency hopping spread spectrum (FHSS)
- 6. 6.6 Figure 6.29 Frequency selection in FHSS
- 7. 6.7 Figure 6.30 FHSS cycles
- 8. 6.8 Figure 6.31 Bandwidth sharing
- 10. 6.10 Figure 6.33 DSSS example