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  • #55395
    vivek
    Guest

    Can any one pls let me know that why do we get RX LEVEL in negative value only..?

    #55396
    pix
    Guest

    rxlev is in dBm unit.
    0dBm = 1mW
    -3dBm = 0.5mW

    and so on…
    when you receive a signal from a BTS, the signal is way below one milliwatt ! so that’s why it’s around -70dBm.

    you’ll find the conversion formula on internet.

    #55397
    MKT
    Guest

    There is nothing like positive power or negative power.

    The negative sign signify the LOSS in system and the positive sign signify the GAIN in system.

    Now as far as GSM is concerned.

    Let us assume that Transmitter is transmitting at 2W. W=watt which is the absolute power.

    Then at Receiver the power received will be less then 2W, because of loss*. let us say 1W.

    Just look at this picture in terms of dBm.

    Here reference is 1mW.

    You will measure the received power wrt 1mW.

    Ease to work with dBm unit in terms of calculations , graphs etc is the reason that wireless engineers prefer dBm.

    Regards

    #55398
    Pix
    Guest

    MKT >

    The negative value of the RxLev means there is a loss?

    — Absolutely not —–

    It’s the power measured by the antenna of the MS. The actual power.
    Such as O.OOOOOO1 mW.

    It’s negative because the unit “dBm” is like this.

    #55399
    vivek
    Guest

    THANKS Pix…!!
    even i found the same answer on wikipedia..!!

    Thanks a lot for ur quick response.

Viewing 5 posts - 1 through 5 (of 5 total)
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