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Thread: Radio distortion at Sub-870MHz

  1. #1

    Default Radio distortion at Sub-870MHz

    Hi,

    Any best guesses what this screen capture (appended) could mean in an environment of industrial metal processing? Particularly, the interest is in possible disturbance to a radio network operating at 868.3 MHz.

    Various kind of production machinery from welding machines, heat ovens, flame-cutting machines and press brakes are operated in the facility all the time and automatically so identifying a possible source is a challenging task as there aren't many possibilities to stop any machines and see. While moving around the machinery, there is no noticable, huge variation in the signal to observe, the appended screenshot does picture well the entire 15 minutes of cruising around. Which one of the machinery could be causing the radio distortion?

    At the identified distortion of 869.3-870.3 MHz, the maximum values for amplitude lay at -40 and density at 20% ... could this still have an impact on the radio network at 868 MHz?

    Thanks for any response!
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  2. #2
    Join Date
    Mar 2010
    Location
    Southern Wisconsin
    Posts
    136

    Default

    Hard to say.. Could be anything quite frankly.. Do you have a recording or image of the entire 800mhz range? I would suggest (if you want to find it) getting a directional for the Wi-Spy and using that to locate it.. Probably a flat panel or parabolic. Motors of all sorts could be giving this off and yes it may interfere with the 868 mhz range however, i think it will probably be ok in the long run.

    Reduce the location down to a small area and start pointing at everything and at a high resolution.. That should help find it. I noticed you did get closer to it and farther away from it in your image, so I imaging it will be possible to "kinda" locate it. Will you be able to find the exact device - yes with effort..

    Oxygen

  3. #3

    Default

    I am new to this Freq. range, but I would say that it is at least two different sources. Notice that the "hotter" trace is not centered in the larger "mound".

  4. #4

    Default

    Did you rule out channel 1019 in the cellular band? Looks a bit like a CDMA carrier but not exactly. I have seen industrial equipment disrupt 1xRTT cellular data services when there was a machine that sprayed strong RF in the reverse link cellular band pass. My team tracked it down to a machine that was made in Japan but the local government, in Bangkok Thailand, would not force the issue.

    Interested in what you found.
    Greg

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