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RBS900 with high 1800Mhz harmonics

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  • 29th July 2010 at 14:57 #63870
    Suzi
    Guest

    hi
    Anyone have similar issue in ericson RBS? Some sites 900Mhz have strong 1800/1900Mhz harmonics, causing interference to other 1800 cells. TRX were checked but it is not. maybe antenna?
    thanks for help

    29th July 2010 at 18:48 #63871
    pix
    Guest

    hi suzi,

    you can precisely compute the 1800MHz harmonics. what are your ARFCN of the 900MHz sector?

    this happens when the DL frequencies of 2 TRX (or more) of the same sector are combined on the same antenna.

    f1(DL) + f2(DL) = 1800 MHz frequency (UL or DL)
    The most dangerous harmonic is one which falls within the UL band. Because even a weak signal will probably interfere strongly with the UL from the MS.

    to avoid intermodulation in the 900 site, you should avoid combining the Tx signal. in other words, bypass your combiner or find a way to avoid combining these 2 freq together.
    another solution : change your 900MHz frequencies so that the harmonics are far away from your 1800MHz band.

    regards
    pix

    30th July 2010 at 14:58 #63872
    Suzi
    Guest

    Thanks a lot for the idea.
    I will check our configuration if it falls under the case you described.
    Thanks again.

    10th April 2014 at 15:30 #63873
    kishore
    Guest

    Hi, What is the range of strong harmonics in 1800band. I’m getting the -40dBm exactly at 10Mhz away from radiating frequency. What might be the reason, plz help.

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