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Thread: All about rx level

  1. #1
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    All about rx level

    Rx level means Received Level, it is the level which mobile receives. It is calculated from below given formula:

    RxLev(dbm) = EiRP(dbm) - Path Loss(db)

    Free Space Path Loss(db) = 32.44 + 20log(d) + 20log(f) in our case I have taken in vacuum environment

    EiRP(dbm) = Antenna Output Power(dbm) + Antenna Gain(dbi)

    for example:

    EiRP = 52dbm, FSPL = 94.64db (1.5km, f = 890.2MHz)

    RxLev(dbm) = 52 - 94.64 = -42.64dbm

    Difference between Rx_Level_Full & Rx_Level_Sub : Rx_Level_Full is measured when DTX is off & Sub is when DTX is on.
    RX Lev Full: Its is nothing but the Mobile transmit the measurment report(SACCH multiframe) for every 480ms. this multiframe containes 104 TDMA frames, in 104 TDMA frames 4 TDMA frames for Decode the BSIC and remaining 100 TDMA frames for Average measurment of serving cell and neighbouring cell.This average measurment of 100 TDMA frames are RX Lev Full

    RX Lev Sub: DTX is a discontinouse trasmission, When the mobile conversation 40% of the time either Trasmitter or Receive is idle. When DTX is ON, DTX will switch off the Trasmitter or Receiver when they is no speech Pulses. only few TDMA frames will trasmit, the average of this TDMA frames is called RX Lev Sub, give you proper measurment of RX level...

    Why Rx_Level is negative??
    1-The measurements of power is expressed in decibels ( dB) rather than the Watt because of the wide range of power levels in RF signals.

    2-Generally the letters (dB) with another character or more tacked on the end means dB compared to some value that the character represents.

    3-For analyzing radio system , was found that dBm convention is more convenient than using Watt convention ( regarding to the calculations, graphics, comparing ….etc )

    4-dB refers to a ratio and dBm refers to a specific power level .
    5-In Our case "m" as in dBm , it's referenced to a value of miliWatt of power .

    6-dBm can have either positive value or negative value , where the positive values indicates we have gain in the power and the negative values indicates we have loss in the power

    7-In a nother word A Negative No. means less than a 1 milliwatt and a positive No. means more than a 1 milliwatt.

    -3dBm=1/2 mW and so on .....

    To know interesting facts about Rx_Quality just click below:

    You may also like given blog about DTX.

    Similar Threads:
    Last edited by telecominfo; 12-29-2011 at 06:55 PM.

  2. Thanks m.z.a.e,, diand thanked for this post
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  3. #2
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    very very essential note....


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