Method and apparatus for detecting a set up signal used for data communication over a communication network

摘要

A method of detecting a set up signal having a predetermined frequency and used for data transmissions over a communication network comprises comparing an energy level of a filtered received signal with a first predetermined value and providing a first detect signal, comparing an energy level of a component of the received signal at a predetermined frequency with a second predetermined value and providing a second detect signal. In addition, an autocorrelation function is performed on the received signal to discriminate between the set up signal and other signals in the received signal, and a check signal is provided when the autocorrelation function identifies the set up signal. The set up signal in the received signal is detected in response to the first and the second detect signals and the check signal. A method of detecting phase reversals in the set up signal is also disclosed.

主权项

1. A method of detecting a set up signal used for data transmissions over a communication network, the set up signal having a predetermined frequency, comprising:
filtering a received signal by a filter having a passband including the predetermined frequency, determining an energy level of the filtered received signal and comparing the determined energy level of the filtered received signal with a first predetermined value and providing a first detect signal when the determined energy level is greater than the first predetermined value; identifying a component of the received signal at the predetermined frequency and determining an energy level of the identified component, comparing the determined energy level of the identified component with a second predetermined value and providing a second detect signal when the determined energy level is greater than the second predetermined value; performing an autocorrelation function on the received signal to discriminate between the set up signal and other signals in the received signal and providing a check signal when the autocorrelation function identifies the set up signal; detecting the set up signal in the received signal in response to the first and the second detect signals and the check signal; and detecting phase reversals in the set up signal when determined energy levels comprising the determined energy level correspond to a predetermined pattern.