1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

[REQ] Frequency hopping transmitter and receiver

Discussion in 'General Electronics Chat' started by junaid766, May 31, 2009.

  1. junaid766

    junaid766 New Member

    Joined:
    Oct 24, 2008
    Messages:
    14
    Likes:
    0
    Location:
    Lahore
    i want to make a frequency hopping AM transmitter and receiver .i want to know that how can i synchronize the receiver frequency
     
  2. RadioRon

    RadioRon Well-Known Member

    Joined:
    Oct 7, 2005
    Messages:
    1,755
    Likes:
    53
    Location:
    BC, Canada
    from Wikipedia:
    --------------------------------
    Basic algorithm

    Typically, the initiation of an FHSS communication is as follows

    1. The initiating party sends a request via a predefined frequency or control channel.
    2. The receiving party sends a number, known as a seed.
    3. The initiating party uses the number as a variable in a predefined algorithm, which calculates the sequence of frequencies that must be used. Most often the period of the frequency change is predefined, as to allow a single base station to serve multiple connections.
    4. The initiating party sends a synchronization signal via the first frequency in the calculated sequence, thus acknowledging to the receiving party it has correctly calculated the sequence.
    5. The communication begins, and both the receiving and the sending party change their frequencies along the calculated order, starting at the same point in time.
    -----------------------------------------
    To simplify things, you might want to simply use a predefined sequence of channels and program this sequence into both transmitter and receiver. Then the only issue is synchronization. I think the most common method is where the transmitter sends a command to "jump to next channel" and then goes ahead and does so. There must be a gap of time to allow the receiver to change channel too, a gap that must account for the time needed for the hardware to change frequencies and settle. If you are keen on efficiency, the frequency change can be triggered by a particular state being reached in a clock.
     
  3. junaid766

    junaid766 New Member

    Joined:
    Oct 24, 2008
    Messages:
    14
    Likes:
    0
    Location:
    Lahore
    thanks for ur reply
    what will b the easiest method i can use to keep both end synchronize while hopping
     

Share This Page