#34 Negative distances

v1.2
open
nobody
Backend (20)
5
2008-09-02
2008-09-02
No

With two different SonyEricsson K800i, and two different bluetooth dongles, it shows always negative distances:

-12 at 50cm, -7 at 1m, and so on...

The min/max data indicates: min:-31 max:255

This is the Hardy (1.2.4 version). Please, order me any other data you need.

Thanks.

Discussion

  • Lars Friedrichs

    Lars Friedrichs - 2008-09-04

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    This is kind of strange but still possible. On my original setup the rssi value that is measured only leaves negative values. I looked at several other systems and found that to be true on those too. So I decided to make very simple calculation formula, which is distance = -rssi value...

    you could change that in the source if you want to... the formula should then read distance = 31 - rssi.
    I don't believe there could be a general fix for this. Maybe there could be a corrective shift factor in the settings...

     
  • Manuel Tornos

    Manuel Tornos - 2008-09-05

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    Well, to modify sources is not inside my todo list ;-)

    But it would be a good idea to add a correction rate to the configuration settings. 8-)

     
  • fluithle

    fluithle - 2008-10-09

    I'm also asking for a "distance skew" feature. I'm getting "zero distance" readings through an office wall, and negative readings when I put the device right next to the receiver (a Lenovo R60 notebook in my case).

    So in order to set up accurate unlock parameters I would have to be able to either (a) set negative values or (b) normalize the distance values to "my own" zero.

    I suggest to introduce a feature similar to the "reset min/max" button, which would not only reset the recorded readings, but also normalize the scale to the lowest received distance value (for example, if the recorded minimum is "-10", clicking that button would set the new zero to "-10", putting a 10 point skew to the value).

    Or simply make it configurable with a text input field.

     

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