What Is Spread Spectrum Techniques?

What are the different spread spectrum techniques?

There are four techniques of spread spectrum namely direct sequence spread spectrum (DSSS), frequency hopping spread spectrum (FHSS), chirp spread spectrum (CSSS) and time hopping spread spectrum (THSS).

Chapter four discusses different multiple accesses of spread spectrum..

What is DSSS technique?

In telecommunications, direct-sequence spread spectrum (DSSS) is a spread-spectrum modulation technique primarily used to reduce overall signal interference. The direct-sequence modulation makes the transmitted signal wider in bandwidth than the information bandwidth.

Does WiFi use spread spectrum?

Bluetooth uses Frequency Hopping Spread Spectrum (FHSS) and is allowed to hop between 79 different 1 MHz-wide channels in this band. Wi-Fi uses Direct Sequence Spread Spectrum (DSSS) instead of FHSS. Its carrier does not hop or change frequency and remains centered on one channel that is 22 MHz-wide.

Why CDMA is called spread spectrum?

CDMA is a form of a Direct Sequence Spread Spectrum (where the transmitted data is coded at a very high frequency) communication. In spread spectrum, to send data, the signal bandwidth is much larger than necessary to support multi-user access.

What is jamming margin?

jamming margin: The level of interference (jamming) that a system is able to accept and still maintain a specified level of performance, such as maintain a specified bit-error ratio even though the signal-to-noise ratio is decreasing. [

What are spreading codes?

A spreading code is a pseudo-random code that has a narrow ambiguity function, unlike other narrow pulse codes. In CDMA a locally generated code runs at a much higher rate than the data to be transmitted.

What is Spread Spectrum?

Spread Spectrum refers to a system originally developed for military applications, to provide secure communications by spreading the signal over a large frequency band. … These narrowband signals are easily jammed by any other signal in the same band.

Where is Spread Spectrum used?

SAW Oscillators and Frequency Synthesizers Frequency hopping (FH) spread-spectrum communications techniques are used to provide low error-rate performance in the presence of jamming or high interference levels.

Which is better FHSS or DSSS?

DSSS, in contrast, spreads the signal across a wider bandwidth than FHSS, creating a lower power density across the spectrum. … Because FHSS allows more channels in the same frequency band, FHSS systems can support a greater aggregate bandwidth for coverage.

Should I disable Spread Spectrum?

Generally, frequency modulation through spread spectrum clocking should not cause any problems. … Therefore, it is recommended that you disable the MCLK Spread Spectrum feature if you are overclocking the memory bus. You will be able to achieve better overclockability, at the expense of higher EMI.

What are the types of FHSS?

FHSS: It combines spread spectrum modulation with MFSK. It is the process of modifying frequency of MFSK signal using frequency hope generated by bits of PN sequence. 5) If more than one symbol are transmitted in single it is called as slow frequency hopping. In slow frequency hopping – Rate of change of symbol.

What is a jamming attack?

A jamming attack is the transmission of radio signals that disrupt communications by decreasing the Signal-to-Inference-plus-Noise ratio (SINR) (Berg, 2008). SINR is the ratio of the signal power to the sum of the interference power from other interfering signals and noise power.

Which is better for avoiding jamming?

Explanation: Frequency hopping spread spectrum is better for avoiding jamming.

What is advantage of spread spectrum technique?

The main advantage of spread spectrum communication technique is to prevent “interference” whether it is intentional or unintentional. The signals modulated with these techniques are hard to interfere and cannot be jammed. An intruder with no official access, is never allowed to crack them.

What is jamming in spread spectrum?

Jamming is a deliberate attempt to disrupt communication between the transmitter and the receiver. … Since spread spectrum signals are wide, they transmit at a much lower spectral power density, making it less likely to interfere with narrowband communications.

Who invented spread spectrum?

Hedy LamarrHedy Lamarr (/ˈheɪdi/), born Hedwig Eva Maria Kiesler (November 9, 1914 – January 19, 2000), was an Austrian-American actress, inventor, and film producer. She was part of 30 films in an acting career spanning 28 years, and co-invented an early version of frequency-hopping spread spectrum.

What are the two types of spread spectrum?

Out of many Spread Spectrums, this report analyses the two main spread spectrum systems which are the ‘Frequency Hopping and Direct Sequence’ and in addition an overview of the ‘Chirp Spread’ Spectrum.

What is spectrum in data communication?

Spectrum refers to the invisible radio frequencies that wireless signals travel over. … The portion used for wireless communication sits within that space and ranges from about 20 KHz to 300 GHz. Spectrum wavelengths are classified into different bands within the electromagnetic spectrum range.

What are the applications of spread spectrum?

Current applications of spread spectrum technology include wireless LANs (local area networks), bar code scanners, and microphones. This technology improves the efficiency and effectiveness of business processes, many of which are finding that wireless communications are requisite for success.

What are the three main types of shift keying?

As with analog modulation, there are three parameters of the carrier wave to vary and therefore three basic types of shift keying: Amplitude Shift Keying (ASK) Frequency Shift Keying (FSK), and. Phase Shift Keying (PSK).