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Spread spectrum is a technique that is used to reduce the impact of localized frequency interferences. To achieve this, it uses more bandwidth than the system needs. There are two main spread spectrum modalities: direct sequence and frequency hopping. The principle of direct sequence spreads the signal on a larger band by multiplexing it with a code (signature) to minimize localized interference and noise. The system works over a large band. To spread the signal, each bit is modulated by a code. Products & Services
Wireless modems transmit modulated data using electromagnetic waves.
Access points are transmitter / receivers (transceivers) that connect to a network through an interface such as a bus or connector. They receive, store, and transmit data between the wireless LAN and the wired structure.
Radio modems are radio frequency transceivers for serial data. They connect to serial ports (RS232, RS422, etc.) and transmit to and receive signals from another matching radio modem.
RF transmitters are electronic devices consisting of an oscillator, modulator, and other circuits that produce an RF signal.
RF modules are partially finished circuits that can be incorporated into larger designs.
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Topics of Interest
Bandwidth utilization is the use of available bandwidth to achieve specific goals.
Efficiency can be achieved by using multiplexing; privacy and antijamming can be
achieved by using spreading.
(Read More)
6.3 RECOMMENDED READING
For more details about subjects discussed in this chapter, we recommend the following
books. The items in brackets [. . .] refer to the reference list at the end of the text.
(Read More)
Multiplexing combines signals from several sources to achieve bandwidth efficiency; the
available bandwidth of a link is divided between the sources. In spread spectrum (SS), we
also combine signals...
(Read More)
The direct sequence spread spectrum (DSSS) technique also expands the bandwidth
of the original signal, but the process is different. In DSSS, we replace each data bit
with n bits using a spreading...
(Read More)
The frequency hopping spread spectrum (FHSS) technique uses M different carrier
frequencies that are modulated by the source signal. At one moment, the signal modulates
one carrier frequency; at the...
(Read More)
Technical Articles
IEEE 802.11 for Industrial Applications
- Networking Equipment
Industrial Wireless - Selecting a Wireless Technology
- RF, Microwave, and Wireless Components
Overcoming UWB Antenna Design Challenges With FDTD Software
- Industrial Software
Frequencies For RFID Systems
- Libraries
Fourier Analysis and FFT
- Data Acquisition and Signal Conditioning
Getting From Here to There: Serial Communications Systems
- Networking Equipment
Beginners Guide to Cellular Technology
- Industrial Software
Electrical Engineering Tutorials
- Training
Optics & Lenses - Industry Glossary
- Optical Components
IC Packages
- Sizes and Specifications
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