Patent ID: 7155171

Claim:
A system comprising: a test signal injector which interlaces test signals with communications signals, wherein one or more of the test signals is a linear FM sweep; a transmitter which transmits said interlaced test signals over a wireless communications path; a test signal receiver which receives said interlaced test signals and determines measurements of amplitude versus frequency and phase-shift versus frequency characteristics of the propagation path; and a signal processing circuit which uses one or more of said measurements to correct for effects of the propagation path on the communication signals; wherein the test signal receiver comprises: an adjustable signal generator which generates a facsimile of said test signals; a down converter which uses said facsimile signal to heterodyne said received test signals to obtain a down converted signal; and a logical processor capable of analyzing said down converted signal and providing a control signal to said adjustable facsimile signal generator to adjust one or more parameters of said adjustable facsimile signal generator, determining information regarding a number of revolutions about an origin point in a two-dimensional plane representing in-phase and quadrature samples of the down converted signal, and determine information regarding the time base offset between the test signal and the facsimile signal using the determined information regarding the number of revolutions.