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iDEN amplifiers range

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  • iDEN amplifiers range

    Hi was interested in finding out first how much range I can get out of the iDEN amplifiers and how to figure out. My industry is trucking and I manage a team of about 50 employees who travel all over the country.

  • #2
    Amplifier Range for iDEN (or CDMA, GSM for that matter)

    1) iDEN works at 800MHz portion of the radio spectrum that is reserved for SMR (specialized mobile radio) service. Since it uses a different frequency based and channel spacing (25Khz slots) the radio (cellphone, amplifiers) & antennas are not compatible with PCS (Sprint), CDMA (Alltel, Verizon) hardware.
    2) Difficult to predict RF signal propagation from tower to phone to estimate how far a cellular amp can work. One thing one can do is estimate how much gain they will get and use this together with information of how badly off they are and what signal strength they nee.

    Here's how:
    a) Need to get received signals strength in dBm for the mobile device. For aircards this is readily available in connection manager. For phones see this forums for how to put a phone in test mode to get this info.
    b) typically most radios sensitivity (minimum received signal they need to work) is above ~ -100dBm. Of course the less negative the better (the higher the received power). So if your current RSS (received signal strength is -120dBm and amplifier with 60dB of gain then resulting effective RSS will be -60dBm (if you account for antenna & cable losses your actuall RSS will be worse than -60dBm but you get the point). So if your phone/aircard normally works at this signal level then the amplifier will help.
    c) normally you can get several miles of amplification but this is dependent on a lot of things e.g
    i) topology - hilly area worse than flat terrain
    ii) environmental condition - rain bad for signal propagation
    iii) obstacles - trees, buildings etc
    iv) multi-user interference - co-channel & adjacent channel interference. The more the users connected to the same tower the worse it is for everyone. Recall that iDEN uses Frequency domain & Time domain duplexing (6times slots of 25khz each with full-duplex or half-duplex in each) to separate multi-users as opposed to CDMA that just uses as wide-band pseudo-noise spreading code to separate users operating in the same frequency.

    I'm sure there's nice simple rule-of-thumb estimates for pathloss computations assuming simple log-normal fading ... if I run into any i will post them here.

    Caveat: I pulled all this stuff from memory and may have some inconsistent or downright erroneous info. I humbly accept any corrections.
    KF7RCQ

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