Introduction to Frequency Hopping Spread Spectrum

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					      Introduction
           to
Frequency Hopping Spread
        Spectrum

           - Supreet Tare
                               Recap
•   When was Nicola Tesla born?
•   With who did he started working in Paris?
•   Apart of Frequency Hopping why is Tesla known for?
•   What was the need for which Tesla came up with Frequency
    Hopping mechanism?
•   How is it that Tesla achieved Security for his submersible boat?
•   Explain the basic concept of Frequency Hopping.
•   What is the definition for FHSS?
•   What were the other systems that make use of FH during early
    nineties?
•   What are the advantages of Frequency Hopping?
•   What are the areas of application where FH can be used?
      Various type of Spread Spectrum
                 Techniques
•   Frequency Hopping Spread Spectrum (FHSS)
•   Direct Sequence Spread Spectrum (DSSS)
•   Time Hopping Spread Spectrum (THSS)
•   Chirp Spread Spectrum
                      FHSS Algorithm
• The initiating party sends a request via a predefined frequency or control
  channel.
• Once the receiving party have received the request, it sends a pseudo
  number called seed to the transmitting party via the same channel.
• The initiating party uses this seed as a variable in predefined algorithm
  and calculates the sequence of frequencies that must now be used to
  transmit the signals. Most often the period of frequency change is
  predetermined.
• The initiating party then sends the first piece of information via the lowest
  band of newly generated frequency spectrum. Thus acknowledging the
  receiving party that it has correctly calculated the sequence.
• The communication begins, and both the receiving party and the sending
  party change the frequencies along with the calculated order. Starting at
  the same point of the time.
                    FHSS Algorithm




In FH Data is divided into chunks and transmitted at different frequencies at
different times.
                                                                Image source: GlobalSpec.com
                Advantages of FHSS
•   Highly restraint to narrowband interferences.
•   Low probability of Intercept.
•   Bandwidth becomes sharable.
•   Improved system efficiency.
• Thank You




  – Supreet Tare
  – Lecturer, Electronics and Communication
  – Shriram Institute of Technology, Jabalpur

				
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posted:6/21/2012
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