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Communication system to simultaneously operate a plurality of RF transceivers in a confined area

  • US 4,479,246 A
  • Filed: 08/29/1983
  • Issued: 10/23/1984
  • Est. Priority Date: 07/23/1981
  • Status: Expired due to Fees
First Claim
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1. In a method of eliminating interference in a wireless communication system located in a predetermined dimensioned enclosed area wherein said system includesat least three portable receiving and transmitting units;

  • at least three base receiving means;

    at least three base transmitting means;

    base transmitter radiating means;

    base receiver radiating means; and

    portable receiver and transmitter radiating means wherein all of said portable receiving and transmitting units, said base receiving means and said base transmitting means can operate simultaneously when there is movement of said portable units in said predetermined dimensional enclosed area comprising the steps of;

    connecting the output signal of each of said base transmitting means to its respective signal radiating means;

    connecting the input signal of each of said base receiving means to its respective signal radiating means;

    connecting the output and input signals of each of said portable receiving and transmitting units to its respective signal radiating means;

    positioning said base transmitter radiating means and said base receiver radiating means so that the difference between the minimum propagation loss and the maximum propagation loss between said base transmitter radiating means and portable receiver and transmitter radiating means is minimized and the difference between said base receiver radiating means and said portable receiver and transmitter radiating means is minimized;

    reducing high level mixing and receiver IM in said portable receiving and transmitting units; and

    selecting transmitter power outputs such that an acceptable system operating margin is achieved and which at the same time avoids RF fields that would result in harmful desensitization of said portable receiving and transmitting units;

    the improvement of selecting system operating frequencies such that all third order intermodulation products generated from the mixing of signals are different from operating frequencies of any of said portable receiving and transmitting units is achieved in accordance with the formulas;

    
    
    space="preserve" listing-type="equation">2F.sub.2 -F.sub.3 =F.sub.4
    
    
    space="preserve" listing-type="equation">F.sub.2 -S=F.sub.1
    
    
    space="preserve" listing-type="equation">S+F.sub.3 =F.sub.4
    
    
    space="preserve" listing-type="equation">F.sub.2 +B=F.sub.4
    
    
    space="preserve" listing-type="equation">(m-1)d+F.sub.1 =F.sub.mWhereFm=A portable receive frequency as m goes from 1 to Nd=the channel spacing which is the difference frequency between two adjacent operating frequenciesF1 =lowest portable receiving unit frequencyF2 =lowest portable transmitting unit frequencyF3 =highest portable receiving unit frequencyF4 =highest portable transmitting unit frequencyS=the separation (or split) in frequency between a given portable'"'"'s receive and transmit frequencies and is the same for all portablesB=the bandwidth needed for the portable transmit frequencies (or receive frequencies since they only differ by a constant S).

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