Patent ID: 8189651
Filing Date: 2012-05-29
Classification: H04B

Abstract:
1. A method for measuring Hum in a digital television (TV) signal comprising quadrature amplitude modulation (QAM) signals using a testing device for testing QAM signals on a cable TV network, the method comprising: a) receiving the digital TV signal with the testing device, which comprises a tuner, a QAM demodulator coupled to receive a digital channel signal from the tuner, and a controller having memory, the QAM demodulator including an automatic gain control (AGC) circuit, the AGC circuit including an AGC register for storing a current AGC value, b) sampling values stored in the AGC register at a pre-defined sampling rate R that exceeds a characteristic Hum frequency to obtain a plurality of AGC register values; c) providing the plurality of AGC register values to the controller for analysis to obtain one or more Hum characteristics; and, d) reporting to a user or storing in memory the one or more Hum characteristics.