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What is spread spectrum and its types?

In telecommunication and radio communication, spread-spectrum techniques are methods by which a signal (e.g., an electrical, electromagnetic, or acoustic signal) generated with a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth.

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In telecommunication and radio communication, spread-spectrum techniques are methods by which a signal (e.g., an electrical, electromagnetic, or acoustic signal) generated with a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth.

Which technique is most popular for spread spectrum?

Frequency-Hopping Spread Spectrum (FHSS)

The latter method, the most common, allows several consecutive data bits to modulate the same frequency. FFHSS is characterized by several hops within each data bit. The transmitted spectrum of a frequency-hopping signal is quite different from that of a direct-sequence system.

What is spread spectrum modulation technique?

A collective class of signaling techniques are employed before transmitting a signal to provide a secure communication, known as the Spread Spectrum Modulation. ... These spread spectrum signals transmit at low power density and has a wide spread of signals.

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.

Why CDMA is called spread spectrum?

To permit this without undue interference between the users, CDMA employs spread spectrum technology and a special coding scheme (where each transmitter is assigned a code). CDMA optimizes the use of available bandwidth as it transmits over the entire frequency range and does not limit the user's frequency range.

How many types of spread spectrum techniques are used in CDMA?

The DS-CDMA system uses two types of spreading sequences, i.e., PN sequences and orthogonal codes. As mentioned above, the PN sequenc is generated by the pseudo-random noise generator.

How can spreading be achieved?

Answer: The spreading can be achieved by two different ways. (3 points)Direct sequence spread spectrum (DSSS): The DSSS system take a user bit stream and perform an (XOR) with a so-called chipping sequence. For each user bit with duration tb, a chip sequence with a smaller duration tc for each chip.

What is the importance of spreading gain in Dsss?

DSSS spreading gain

It is found that the larger the spreading gain of the direct sequence spread spectrum signal, the more effective the performance of the system is. This is because the wanted signal becomes larger.

What is the disadvantage of spread spectrum?

Involves low power spectral density since signal is spread over a large frequency band. Disadvantages: Bandwidth inefficient; • Implementation is somewhat complex. Two of the most popular techniques that provide spectrum spreading in a spread spectrum system are direct sequence and frequency hopping.

Which is better CDMA or GSM?

GSM users can experience better voice quality than CDMA users or vice versa in particular areas. Furthermore, the GSM network can transmit voice and data simultaneously. On the other hand, not all CDMA phones can transmit voice and data at the same time.Jan 6, 2020

image-What is spread spectrum and its types?
image-What is spread spectrum and its types?
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Is WIFI spread spectrum?

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. While there is room for 11 overlapping channels in this 83 MHz-wide band, there is only room for three non-overlapping channels.

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Is Bluetooth spread spectrum?

Instead of transmitting over one frequency within the 2.4 GHz band, Bluetooth radios use a fast frequency-hopping spread spectrum (FHSS) technique, allowing only synchronized receivers to access the transmitted data.May 15, 2021

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What is CDMA and how it works?

Code Division Multiple Access (CDMA) is a sort of multiplexing that facilitates various signals to occupy a single transmission channel. It optimizes the use of available bandwidth. The technology is commonly used in ultra-high-frequency (UHF) cellular telephone systems, bands ranging between the 800-MHz and 1.9-GHz.

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Is LTE a spread spectrum?

LTE is a broadband wireless technology that uses wide channels to achieve high data rates and accommodate lots of users. The standard is set up to permit bandwidths of 1.4, 3, 5, 10, 15, and 20 MHz. The carrier selects the bandwidth depending on spectrum holdings as well as the type of service to be offered.Jan 8, 2013

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What is spread spectrum used for?

  • Spread spectrum is a technology originally developed for military applications to provide secure communications by spreading the transmitted signal over a large frequency band. This spread signal is not clearly distinguishable in the spectrum, and consequently more difficult to jam or intercept.

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What are the disadvantages of spread spectrum?

  • The Direct Sequence Spread Spectrum or DSSS system takes large acquisition time; that's why its performance is slow.
  • It requires wide-band channels with small phase distortion.
  • In DSSS,the pseudo-noise generator generates a sequence at high rates.

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What is spread spectrum technology?

  • Spread spectrum is a form of wireless communications in which the frequency of the transmitted signal is deliberately varied. This results in a much greater bandwidth than the signal would have if its frequency were not varied.

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Who invented spread spectrum technology?

  • Spread spectrum technology saw further development and deployment during World War II. Probably the most famous developer of spread spectrum technology was the actress Hedy Lamarr, who co-patented a frequency hopping technique in 1942 to prevent radio-controlled torpedoes from being detected and jammed.

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What are spread spectrum techniques in communication?What are spread spectrum techniques in communication?

In telecommunication and radio communication, spread-spectrum techniques are methods by which a signal (e.g., an electrical, electromagnetic, or acoustic signal) generated with a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth.

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What is direct sequence spread spectrum?What is direct sequence spread spectrum?

Direct Sequence Spread Spectrum D S S S Frequency Hopped Spread Spectrum F H S S This is frequency hopping technique, where the users are made to change the frequencies of usage, from one to another in a specified time interval, hence called as frequency hopping. For example, a frequency was allotted to sender 1 for a particular period of time.

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Is time hopping a viable alternative spread spectrum technique?Is time hopping a viable alternative spread spectrum technique?

However, the arrival of cheap random access memory (RAM) and fast micro-controller chips make time hopping a viable alternative spread spectrum technique for the future. Time hopping is a system in which burst signal are initiated at pseudo random rate. In this the transmitter is switched ON and OFF by a code sequence.

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How to understand spread spectrum modulation?How to understand spread spectrum modulation?

Spread Spectrum Modulation 1 Narrow-band and Spread-spectrum Signals. Both the Narrow band and Spread spectrum signals can be understood easily by observing their frequency spectrum as shown in the following figures. 2 FHSS and DSSS / CDMA. ... 3 Comparison between FHSS and DSSS/CDMA. ...

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