Estimating time delays in a simulcast communication system

1 . A method for equalizing a number of signals in a simulcast network, said method comprising:

(a) receiving a simulcast signal comprising known data simulcast from at least two different sites;

(b) generating a number of simulated simulcast signals, each simulated simulcast signal being based on at least two sites transmitting said known data with a presumed time delay, each simulated simulcast signal having a different presumed time delay;

(c) determining which of said simulated simulcast signals is an optimum simulated simulcast signal that correlates most closely to said simulcast signal; and

(d) providing time delay data of said optimum simulated simulcast signal for use in equalization of said simulcast signal.

2 . The method of claim 1 , wherein at least a portion of said simulcast signal is a synchronization signal.

3 . The method of claim 1 , wherein generating a number of simulated simulcast signals comprises at least:

i. calculating a vector of channel coefficients as a product of filters and said simulcast signal; and

ii. using said vector of channel coefficients to generate said simulated simulcast signals.

4 . The method of claim 3 , wherein said filters are calculated prior to receiving said simulcast signal and are stored in memory.

5 . The method of claim 4 , wherein said filters comprises two or more sets, a coarse set having coarsely-incremented time delays, and at least one fine set having finely-incremented time delays.

6 . The method of claim 5 , wherein said filters are least square filters.

7 . The method of claim 1 , wherein the number of simulated signals is two.

8 . The method of claim 1 , wherein said simulcast signal has an expected range of time delay and wherein said simulated simulcast signals have time delays spanning essentially said expected range.

9 . The method of claim 1 , wherein said range is about 50 to about 200 μsec.

10 . The method of claim 1 , wherein said simulated simulcast signals are generated in increments of time delay.

11 . The method of claim 1 , wherein,

step (b) generates initially a coarse set of simulated simulcast signals using coarsely-incremented time delays;

step (c) determines initially a coarse optimum simulated simulcast signal from said coarse set of simulated simulcast signals;

step (b) then generates a fine set of simulated simulcast signals based on said time delay of said coarse optimum simulated simulcast signal using finely-incremented time delays which are finer than those used initially; and

step (c) then determines said optimum simulated simulcast signal from said fine set of simulated simulcast signals.

12 . The method of claim 13 , wherein a coarsely-incremented time delay is 5 to 20 times a finely-incremented time delays.

13 . The method of claim 12 , wherein said coarsely-incremented time delay is about 10 times said finely-incremented time delay.

14 . The method of claim 1 , wherein step (c) comprises calculating least square error between each simulated simulcast signal and said simulcast signal.

15 . The method of claim 1 , further comprises:

(e) equalizing said data simulcast from said different sites.

16 . A mobile unit for use in a simulcast network comprising:

a receiver for receiving a simulcast signal;

a transmitter for transmitting a signal to a simulcast network;

a processor operatively connected to said receiver and said transmitter; and

memory operatively connector to said processor and being configured to instruct said process to perform the following steps:

(a) receiving a simulcast signal comprising known data simulcast from at least two different sites;

(b) generating a number of simulated simulcast signals, each simulated simulcast signal being based on at least two sites transmitting said known data with a presumed time delay, each simulated simulcast signal having a different presumed time delay;

(c) determining which of said simulated simulcast signals is an optimum simulated simulcast signal that correlates most closely to said simulcast signal; and

(d) providing time delay data of said optimum simulated simulcast signal for use in equalization of said simulcast signal.

17 . The mobile unit of claim 16 , wherein generating a number of simulated simulcast signals comprises:

i. calculating a vector of channel coefficients as a product of filters and said received simulcast signal; and

ii. using said vector of channel coefficients to generate said simulated simulcast signals; and

wherein said filters are resident in said memory prior to receiving said signal.

18 . A simulcast network comprising:

at least two sites for simulcasting a signal having known data

a mobile unit positionable between said two sites such that a simulcast signal received from said two sites has a time delay, and comprising:

a receiver for receiving a simulcast signal;

a transmitter for transmitting a signal to a simulcast network;

a processor operatively connected to said receiver and said transmitter; and

memory operatively connector to said processor and being configured to instruct said process to perform the following steps:

(a) receiving a simulcast signal comprising known data simulcast from at least two different sites;

(b) generating a number of simulated simulcast signals, each simulated simulcast signal being based on at least two sites transmitting said known data with a presumed time delay, each simulated simulcast signal having a different presumed time delay;

(c) determining which of said simulated simulcast signals is an optimum simulated simulcast signal that correlates most closely to said simulcast signal; and

(d) providing time delay data of said optimum simulated simulcast signal for use an equalization of said simulcast signal.