![greater length than those for the usual areas of data transfer, since it is intended for bandwidth
spreading.
Codes in a spread-spectrum system are used for:
Maximal sequencing is one of the more popular coding methods in a spread-spectrum system.
Maximal codes can be generated by a given shift register or a delay element of given length. In
binary shift register sequence generators, the maximum length sequence is (2^n-1) chips, where
n is the number of stages in the shift register.
A shift register generator consists of a shift register in conjunction with the appropriate logic,
which feeds back a logical combination of the state of two or more of its stages to its input. The
output, and its contents of its n stages at any clock time, is its function of the outputs of the
stages fed back at the proceeding sample time. Some maximal codes can be of length 7 to
[(2^36)-1] chips.
Error detection and correction codes (EDAC) must be used in frequency-hopping systems in
order to overcome the high rates of error induced by partial band jamming. These codes
usefulness has a threshold that must be exceeded before satisfactory performance is achieved.
In direct-sequence systems, EDACs may not be advisable because of the effect it has on the
code, increasing the apparent data transmission rate, and may increase jamming threshold. Some
demodulators can operate detecting errors at the approximately the same accuracy as an EDAC,
so it may not be worthwhile to include a complex coding/decoding scheme in the system.
Advantages of Spread Spectrum
Spread-spectrum systems provide some clear advantages to designers. As a recap, here are nine
benefits that designers can expect when using a spread-spectrum-based wireless system.
1) Reduced crosstalk interference
2) Better voice quality/data integrity and less static noise
3) Lowered susceptibility to multipath fading
4) Inherent security
5 )Co-existence
6) Longer operating distances
Remote monitoring and control refers to a field of industrial automation that is entering a new
era with the development of wireless sensing devices. Initially limited to SCADAtechnology,
remote monitoring and control refers to the measurement of disparate devices from a network
operations center or control room and the ability to change the operation of these devices from
that central office.
Today the application of remote monitoring and control extends from fields such as:](https://image.slidesharecdn.com/spreadspectrumtechniquesdescribeindetailasimpledatacommuni-230327125648-275ad2a6/85/Spread-Spectrum-TechniquesDescribe-in-detail-a-simple-data-communi-pdf-2-320.jpg)
Spread Spectrum TechniquesDescribe in detail a simple data communi.pdf
- 1. Spread Spectrum Techniques Describe in detail a simple data communication system that will monitor the temperature of a remote inaccessible location and display temperature on a personal computer. Suggest a future application for spread spectrum techniques and explain why SS would be appropriate for that application. Solution Spread spectrum communication systems are widely used today in a variety of applications for different purposes such as access of same radio interrupted or blocked by spurious transmission from enemy), interference rejection, spectrum by multiple users (multiple access), anti-jamming capability (so that signal transmission can not be secure communications, multi-path protection, etc. However, irrespective of the application, all spread spectrum communication systems satisfy the following criteria- a) As the name suggests, bandwidth of the transmitted signal is much greater than that of the message that modulates a carrier. b)The power spectral density of the modulated signal is very low and usually comparable to background noise and interference at the receiver. DATA COMMUNICATION: It defines as data exchange between source and receiver. Wireless Sensor Network (WSN) typically consists of small spatially distributed devices to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration and etc. With WSN connectivity, data from remote sensors of different types are collected by central unit for further processing and analysis. WSNs are less expensive and more flexible than wired monitoring systems. There are applications that become feasible only with WSNs because using wires between devices are too expensive or impossible at all. For instance, in many industrial, agricultural, military or ecological problems physical wiring is impossible or would create extreme disturbance for other operations. WSN, compared to other existing wireless technologies, is the only technology that targets simple communication with low data rates and low power consumption. Each WSN node is typically equipped with: Coding Techniques In order to transmit anything, codes used for data transmission have to be considered. However, this section will not discuss the coding of information (like error correction coding) but those that act as noise-like carriers for the information being transferred. These codes are of much
- 2. greater length than those for the usual areas of data transfer, since it is intended for bandwidth spreading. Codes in a spread-spectrum system are used for: Maximal sequencing is one of the more popular coding methods in a spread-spectrum system. Maximal codes can be generated by a given shift register or a delay element of given length. In binary shift register sequence generators, the maximum length sequence is (2^n-1) chips, where n is the number of stages in the shift register. A shift register generator consists of a shift register in conjunction with the appropriate logic, which feeds back a logical combination of the state of two or more of its stages to its input. The output, and its contents of its n stages at any clock time, is its function of the outputs of the stages fed back at the proceeding sample time. Some maximal codes can be of length 7 to [(2^36)-1] chips. Error detection and correction codes (EDAC) must be used in frequency-hopping systems in order to overcome the high rates of error induced by partial band jamming. These codes usefulness has a threshold that must be exceeded before satisfactory performance is achieved. In direct-sequence systems, EDACs may not be advisable because of the effect it has on the code, increasing the apparent data transmission rate, and may increase jamming threshold. Some demodulators can operate detecting errors at the approximately the same accuracy as an EDAC, so it may not be worthwhile to include a complex coding/decoding scheme in the system. Advantages of Spread Spectrum Spread-spectrum systems provide some clear advantages to designers. As a recap, here are nine benefits that designers can expect when using a spread-spectrum-based wireless system. 1) Reduced crosstalk interference 2) Better voice quality/data integrity and less static noise 3) Lowered susceptibility to multipath fading 4) Inherent security 5 )Co-existence 6) Longer operating distances Remote monitoring and control refers to a field of industrial automation that is entering a new era with the development of wireless sensing devices. Initially limited to SCADAtechnology, remote monitoring and control refers to the measurement of disparate devices from a network operations center or control room and the ability to change the operation of these devices from that central office. Today the application of remote monitoring and control extends from fields such as: