Giday from Down under

Discussion in 'Wireless & RF Design' started by fiero128, May 19, 2012.

  1. fiero128

    Thread Starter New Member

    May 13, 2012
    13
    0
    Hi I need to make an Rxer that has 4 aerials and can detect which aerial has the stronger signal.
    The 433 Rxer PCB you guys are talking about is good but i want this to looking at all 4 aerials and tell the operator which direction the signal is comming from.
    I was thinking of diode detectors with LEDs on each output.
    Any one got better ideas

    Allen
     
  2. TecknoTone

    New Member

    May 20, 2012
    21
    1
    It strikes me that this approach is not going to work. For instance, if four antennae are on a vehicle roof, they will all receive a very similar signal level. Where differences in signal strength occur, this will be the result of many factors, a very minor one being the metre or so distance differential in direct propagation path length.
    Here in the Mothercountry, we have police cars which give the bearing of a VHF tracking beacon on a stolen car. These don't work on signal strength though, instead, they examine the phase relationship of each of the four signals.
     
  3. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
    2,040
    287
    Gday from "up over! :)

    What you want to build is called a diversity receiver, and it requires a separate detector (such as AGC) for each antenna. A simple analog "voting circuit" can then route the strongest signal to the audio stage or digital decoder. Very cool methodology and very effective for lousy conditions, by the way.

    Look up Internet references for "diversity reception" for more details.

    Good luck!

    Eric
     
  4. WBahn

    Moderator

    Mar 31, 2012
    17,757
    4,800
    How is that approach going to tell the operator which direction the signal is coming from?

    It would seem like you want to look at the signals from all four antennas (or perhaps look at them in subsets) and look at the phase differences between them to establish a line of arrival for the signal. Two antennas can get you angle of arrival but can't distinguish which side of the line connecting the antennas the signal is coming from. I believe three antennas can and more antennas make it easier and probably improve the resolution of the estimation.
     
    TecknoTone likes this.
Loading...