Method, system, and apparatus for unambiguous phase synchronization

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention provides a method, apparatus and system for efficiently and inexpensively acquiring unambiguous phase synchronization of a RF carrier in a digital communication system.
As is discussed in detail below, a transmitter transmits an original digital code in a transmitted signal component of a transmitted signal to a receiver through a communication channel.
The receiver receives a received signal having a first received signal component and a second received signal component where the transmitted signal component results in the second received signal component.
The receiver determines a phase between the received signal and the corresponding transmitted signal by detecting a resulting digital code in the first received signal component.
The resulting digital code appears in the first received signal component when the received signal is out of phase with the transmitted signal and a component of the original digital code results in the resulting digital code.
Referring to the figures, FIG.
1 is a block diagram of a digital communication system in accordance with the present invention.
In the preferred embodiment of the invention, a transmitter 104, using quadrature amplitude modulation (QAM) signaling, encodes a binary code into one of the components (e.
g.
"I" component) of the QAM signal.
The receiver 108 attempts to detect the binary code in the other component (e.
g.
"Q" component).
If the binary code is detected by the receiver 108, the received signal is not phase aligned with the transmitted signal and the received signal is phase rotated.
Although in the preferred embodiment the communication system is an advance television digital system 100, any synchronous digital communication system may be employed.
An advance television digital system 100 comprises an advance television digital camera 102 for capturing advance television video images.
The advance digital television camera 102 sends the video images to an advance digital television transmitter 104