Define Spread Spectrum and its goal. List the two spread spectrum techniques.

Introduction

Spread Spectrum is a technique used in data communication for spreading the bandwidth of the data signal over a larger frequency band. This technique is primarily used to ensure that the signal is resistant to interference, noise, and eavesdropping.

Definition of Spread Spectrum

In data communication, Spread Spectrum is a method where a signal generated with a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth. This technique is used to reduce the power density (the power per unit of spectrum) of the transmitted signal which makes it less susceptible to interference and detection.

The importance of Spread Spectrum in data communication lies in its ability to provide secure and reliable communication. By spreading the signal over a wide frequency band, it becomes difficult for an eavesdropper to intercept the signal. Furthermore, by reducing the power density of the signal, it becomes less susceptible to interference from other signals.

Goal of Spread Spectrum

The primary goal of Spread Spectrum is to prevent interference and provide secure communication. This is achieved by spreading the signal over a wide frequency band, which makes it difficult for an eavesdropper to intercept the signal and reduces the signal's susceptibility to interference.

The benefits of achieving the goal of Spread Spectrum in data communication include secure and reliable communication, resistance to interference and noise, and improved signal quality.

Spread Spectrum Techniques

There are two main Spread Spectrum techniques: Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS).

Frequency Hopping Spread Spectrum (FHSS)

FHSS is a spread spectrum method where the data signal is broadcast over a seemingly random series of radio frequencies, hopping from frequency to frequency at fixed intervals.

In FHSS, the available bandwidth is divided into multiple frequency slots, and the signal hops between these slots in a predetermined sequence. This technique is used in situations where the communication channel is subject to interference or jamming.

Direct Sequence Spread Spectrum (DSSS)

DSSS is a spread spectrum technique where the data signal is multiplied with a pseudo-random noise spreading code, resulting in a wideband time continuous scrambled signal.

In DSSS, the data bits are spread over a large frequency band, and the receiver must know the spreading code to recover the original data. This technique is used in situations where secure communication is required.

Comparison of FHSS and DSSS

Conclusion

In conclusion, Spread Spectrum is a crucial technique in data communication that ensures secure and reliable communication by spreading the signal over a wide frequency band. The two main Spread Spectrum techniques, FHSS and DSSS, offer different advantages depending on the situation, with FHSS being more suitable for environments with interference or jamming, and DSSS being more suitable for secure communication.

Diagram: Not necessary for this question.

Summary

Spread Spectrum is a technique used in data communication for spreading the bandwidth of the data signal over a larger frequency band. Its goal is to prevent interference and provide secure communication. The two spread spectrum techniques are Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS).

Analogy

Spread Spectrum is like spreading butter on a toast. By spreading the signal over a wide frequency band, it becomes difficult for an eavesdropper to intercept the signal, just like it's difficult to remove the butter from the entire surface of the toast.