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Technique for measuring channel delay

  • US 5,280,629 A
  • Filed: 12/06/1991
  • Issued: 01/18/1994
  • Est. Priority Date: 12/06/1991
  • Status: Expired due to Term
First Claim
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1. In a simulcast system having a prime transmitter site coupled to a remote transmitter site via a channel, the channel having a delay, the prime transmitter site having a prime clock for providing a first value ("T1") based on the current time at the prime transmitter site, the remote transmitter site having a remote clock for providing a second value ("T2") based on the current time at the remote transmitter site, the prime clock and the remote clock being synchronized with a common timing signal so that T2 equals T1, the simulcast system arranged for determining the worst-case delay in accordance with a predetermined method, the method comprising the steps of:

  • at the prime transmitter site;

    (a) determining T1;

    (b) simultaneous with step (a), sending a first message to the remote transmitter site;

    (c) saving T1;

    at the remote transmitter site;

    (d) receiving the first message;

    (e) simultaneous with step (d), determining T2;

    (f) sending a second message to the prime transmitter site, the second message including T2;

    at the prime transmitter site;

    (g) receiving the second message;

    (h) decoding the second message to determine T2;

    (i) determining the delay based on the difference between T2 and T1;

    (j) repeating steps (a) through (i) z times, thereby determining delay1, . . . , delayz ;

    (k) determining the worst-case delay for the channel based on the maximum delay of the group of delays consisting of delay1, . . . , delayz ;

    (l) waiting a predetermined time, and then repeating steps (a) through (k);

    (m) after step (l), then repeating steps (a) through (l) for a predetermined number(w) of times, thus determining the worst-case delay for the 1st trial, the worst-case delay for the 2nd trial, . . . , the worst-case delay for the (w-1)th trial, and the worst-case delay for the wth trial;

    where z is a predetermined number greater than 1, the predetermined number z being selected to determine the worst-case delay.

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