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Using RSSI to locate an object

Discussion in 'Electronic Design' started by Josh916, Mar 20, 2007.

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  1. Josh916

    Josh916 Guest

    I would like to use RSSI to locate an object in a 3D space. The space
    will be a square box with transmitters located on the 4 corners. An
    object will be place at certain positions within the box and I want to
    be able to determine its location inside the box. Much like an
    internal GPS.

    I would like to know what components (IC's?) I need to perform such a
    task.

    Or if anyone else has any other more effective methods to acheive such
    a task your comments are welcomed.

    Thanks,

    Josh
     
  2. Jamie

    Jamie Guest

    since RSSI devices (most of them) can output analog for a project that
    you have in mind. a uC (microprocessor) would be suited for that.
    Look at the AVR line of programmable chips. You'll need a DEV starter
    kit and learn a little about programming.
    THey have chips that offer multiple ADC (Analog to Digital ) converters.
    With these chips, they have enough power for a HID (Human INterface
    device) or simply output some coded results to your computer via a
    serial port and write some software.
    You may also want to look at Rabbit core embedded processors. With
    those, the hassle has been taken out of making a board. etc.. look
    them up on line.
     
  3. Phil Allison

    Phil Allison Guest

    "Josh916" <>

    ** Groper alert.

    ** And when did you come up with this nut case idea?

    Or was it someone else's ?


    ** How do you know it can even be done to any degree of accuracy ?


    ** You better explain the task much more clearly, with all the details.

    Or it qualifies as yet another:

    " Novice needs help with CRAZY project" TROLL.




    ....... Phil
     
  4. When is your assignment due?

    Do you have to use RSSI?
    How big is your box?
    Can you use any object?

    One alternative way to do it would be with visual object recognition
    using a camera on each side of the box.

    For using RSSI I would have thought that you would have to use 4
    receivers and the object is the transmitter?

    Dave.
     
  5. RSSI will indicate only the received signal strength, not distance -
    and there are a lot of reasons why an accurate position indicator is
    impractical using only this method, especially in the near field of
    the TX antennas.

    It certainly won't work for VHF and above. I have had some success
    with short range position indicators using 125 kHz sources. If that is
    feasible for you, please indicate the dimensions you are working with.

    Frank Raffaeli
    http://www.aomwireless.com/
     
  6. Don Bowey

    Don Bowey Guest

    Which 4 corners of the 8-cornered box do you plan to use?

    Don
     
  7. Phil Allison

    Phil Allison Guest

    "Don Bowey"
    "Josh916"


    ** Suspect Josh is more your RSI type than RSSI.



    ...... Phil
     
  8. Yes, Frank is correct.

    If the signal is attenuated in any way.... (eg by antena beam width, objects
    absorbing RF, RF reflections causing canceling or summing effect) then your
    accruacy using RSSI will be shot.

    You should read up on the internet about how GPS using timed signals and
    sequences work to compute location.

    There are so may problems using RSSI accurately for distance.


    Regards
    Joe
     
  9. You can have a look at Chipcon's (now TI) CC2431 Zigbee transceivers : they
    offer a hardware-based location detection feature.
    See http://www.chipcon.com/index.cfm?kat_ id=2&subkat_id=12&dok_id=261,
    claimed spatial resolution is 0,5m over a 64x64m area, with an overall
    accuracy of 3m

    Friendly,
     
  10. chuck

    chuck Guest

    GPS doesn't use RSSI, of course.

    Is the task you want to perform the use of RSSI, or the determination of
    position location with a box? What kind of accuracy do you hope to achieve?

    Have you considered ultrasonic distance measurement?

    Chuck
     
  11. Josh916

    Josh916 Guest

    The project is to locate a r/c boat in a roughly 2 to 3m^2 water
    filled box, hence the transmitters or recievers will only be on the 3
    or 4 walls of the box.

    It will need to be fairly accurate considering the size of the box
    relative to the size of the boat (i.e down to cm's).

    We are also considering placing a webcam above the box and using image
    processing to locate the boat, however I thought we might get more
    accurate results using RSSI.

    I hope that helps.

    Josh
     
  12. Phil Allison

    Phil Allison Guest

    "Josh916" <

    ** Really desperate Groper Alert !!


    ** Huh ??

    This is even LOONIER that I thought !!


    ** Well, you thought wrong.




    ....... Phil
     
  13. This detail would have been useful at the start!
    So is it a 2 dimentional problem or a 3 dimentional problem?
    i.e. can the water level vary?
    If it can vary then you can use a simple water level meter and then
    turn it into a 2 dimentional problem.
    Nope, not a chance. Visual object recognition is the way to go, with a
    water level meter if needed.

    Dave.
     
  14. Phil Allison

    Phil Allison Guest

    "David L. Jones"

    **The OP is utterly confused, he simply has no idea what " 3 dimensions"
    means.

    He describes a box in terms of square area ???

    He says the box is "filled" with water - but is it ??

    He talks of an RC boat - but is it really a RC submarine ??

    Must be if the box is "filled" with water, RC submarines are available.

    Ergo it follows....

    The OP is a just another naive, code scribbler with ZERO comprehension of
    physics or electronics.

    They are now in plague proportions.




    ........ Phil
     
  15. Donald

    Donald Guest

    Josh,

    Your idea has been tried by big governments with big budgets.

    NO, it will not work.

    If you care to read a little, you may find a not so cheap way of doing
    what you want:
    http://en.wikipedia.org/wiki/Pseudolite

    google has lots of links:
    http://www.google.com/search?hl=en&...&resnum=0&ct=result&cd=1&q=pseudolite&spell=1

    good luck

    If you find a way of getting this done, in any home made way,
    please let us know.

    donald
     
  16. Josh916

    Josh916 Guest

    Thanks for everyones help, RSSI was mentioned to me by a fellow
    academic and I'm at the stage of researching its possiblilites.

    He seems to think that it is possible.

    I will keep looking into it as I also have a backup plan using the
    webcam.
     
  17. Phil Allison

    Phil Allison Guest

    "Josh916"

    ** Definitely a RSI expert.

    Got a PhD in " Pure and Applied Wanking" - I bet.


    ** Whaaaaatttt ??

    We are dealing with an academic ??????

    Or is it an academic twat.



    ** ROTFLMAO !!!!

    Then let THAT fucking jerk off show YOU how.


    My earlier summation is now proved CORRECT beyond any doubt:


    " The OP is utterly confused, he simply has no idea what " 3 dimensions"
    means.

    He describes a box in terms of square area ???

    He says the box is "filled" with water - but is it ??

    He talks of an RC boat - but is it really a RC submarine ??

    Must be if the box is "filled" with water, RC submarines are available.

    Ergo it follows....

    The OP is a just another naive, code scribbler with ZERO comprehension of
    physics or electronics.

    They are now in plague proportions. "


    And the unmitigated GALL to call themselves "academics"

    - what a bloody HOOT !!!




    ........ Phil
     
  18. Donald

    Donald Guest

    This I would like to see.

    I too tried in college to use ultra-sonic devices.

    It was just too difficult to get a signal that would work.

    I will admit the technology has improved 1,000 fold over the years.

    However, physics has not.

    Good Luck

    I would be very interested in how you both get this done.

    donald
     
  19. Josh, he is wrong.
    It can be done (sort of) on a larger scale, but at the small scale you
    are talking about it's just not possible as other posters have
    mentioned. You would be lucky to determine if the object is inside the
    box or outside, let alone its position inside.
    Seriously, start your backup plan now. Then it just becomes
    essentially a software project.

    Dave.
     
  20. Josh916

    Josh916 Guest

    Having done some more research today it looks like other posibilities
    include acoustic positioning or infrared positioning (e.g.
    http://instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2004/rd73/476finalpro.htm)

    What does everyone think about the other technologies mentioned above?
     
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