Do XBee-Pro DigiMesh 2.4ghz tranceivers get interfere with other 2.4ghz devices

Discussion in 'Wireless & RF Design' started by vane, Jul 27, 2009.

  1. vane

    Thread Starter Active Member

    Feb 28, 2007
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    basically the name says it all. Do XBee-Pro DigiMesh 2.4ghz tranceivers interfere with wifi access points and 2.4ghz rc plane Transmitters?

    I am making a UAV (i say a UAV, i mean more like an rc plane with a serial connection downlink of information)

    Also can they transmit and receive at the same time?

    Any help would be great!

    Peter

    EDIT: also are they available with an external aerial conector so i can put a high gain aerial on it to increase the range, apparently it is 63mw
     
    Last edited: Jul 27, 2009
  2. John Luciani

    Active Member

    Apr 3, 2007
    477
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    The XBee does channel hop to avoid interference. 2.4GHz ISM band is getting crowded.
    You need to test your situation.

    No. There is a single antenna that is multiplexed. It is low bandwidth (apx 56Kbs) and
    there is buffering. Unless there is a lot of activity in the 2.4GHz band
    then it should appear to be full duplex to your application.

    You can buy the XBee with a co-ax connector and attach your own external antenna.
    There may be legal limits on the gain of the antenna. I am not sure.

    (* jcl *)
     
  3. vane

    Thread Starter Active Member

    Feb 28, 2007
    181
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    are there any tranceivers like the xbe but able to transmit and receive at the same time
     
  4. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    Most of the pre-built Zigbee and Bluetooth modules I have seen have one antenna to keep the costs low.

    Do you really need full duplex? What bandwidth do you need?

    Zigbee is around 56Kbs. You have buffering in the XBee.
    Your uC has buffering. If the radio is busy you will buffer the data until it is
    ready. With the proper coding you can keep the radio busy all the time to get
    the maximum bandwidth.

    (* jcl *)
     
  5. vane

    Thread Starter Active Member

    Feb 28, 2007
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    could i just program one to be a transmitter for like 10 milliseconds and the other be a receiver then swap? i was only thinking of send small bits of information at a time, to begin with i was thinking of making it so i could connect two computers together so i can write a program to send some code over the serial port and via the wireless to the other transceiver which will connect to a second computer's serial port and display the text typed in another program

    I fear i may be a bit ambicious :)

    Vane

    EDIT: also, how do you connect two together? is there like a binding process you need to go through?
     
    Last edited: Jul 29, 2009
  6. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    The XBees handle the multiplexing for you. Send ASCII characters to the TX line.
    Receive ASCII characters from the TX line. Unless you are trying to get close to
    56Kbs, which it sounds like you aren't, you don't need to worry about it.

    The XBees default to a point-to-point communications mode called transparent mode.
    Set the network address id (PAN) to the same value on both nodes.
    Setup matching source and destination addresses. You are done.

    Checkout the applications information in my ZB1 datasheet at
    http://tinyurl.com/5rfmrz

    I also have code examples on my site so you can see how to send
    and receive characters.

    (* jcl *)
     
  7. vane

    Thread Starter Active Member

    Feb 28, 2007
    181
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    Your site looks filled with information that will come in handy for my project thanks! Do the Xbees have like an onboard PIC or something?
     
  8. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    IIRC it is some sort of 8051.

    It has an A/D and digital I/O lines. You can use the XBee without an external uC.

    (* jcl *)
     
  9. vane

    Thread Starter Active Member

    Feb 28, 2007
    181
    0
    so the code you are showing on your site is what is loaded onto the onboard microcontroller?
     
  10. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    The code is loaded onto the ATmega168 uC that communicates to the XBee.
    The code examples use the Arduino libraries (C and C++).

    I do not have any application examples of code that run on the XBee.
    I should have within the next few months.

    (* jcl *)
     
  11. vane

    Thread Starter Active Member

    Feb 28, 2007
    181
    0
    Hopefully soon i will have the funds to fund this project!!! thanks for all your help so far!

    I think the Xbee pro 63mw modules are about £15 each

    Basically the main information that the transceivers were going to be transmitting was latitudinal and longitudinal GPS co-ordinates as well as heading etc from a GPS unit.
     
  12. vane

    Thread Starter Active Member

    Feb 28, 2007
    181
    0
    Also, i don't suppose it is possible to send video and audio via one of these (xbee transceiver) is it?
     
    Last edited: Jul 30, 2009
  13. vane

    Thread Starter Active Member

    Feb 28, 2007
    181
    0
    Sorry, Bump?
     
  14. vane

    Thread Starter Active Member

    Feb 28, 2007
    181
    0
    Anyone answer my question? a quick google search said not likely but i am wondering if anyone has any further information.

    The reason i want to find this out is because 2.4ghz cameras (e.g the cheap ones on ebay) get interfered with by these modules (i know this because my rc transmitter has a 2.4ghz transceiver like the xbee) when you turn on the transmitter the screen goes grainy.
     
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