Performance Monitoring and Management

Is your return path ready for QAM-64 and QAM-128

To increase the return path data rate, QAM-64 or QAM-128 are used in place of QAM-16 or QPSK modulations. Higher QAM signal carries higher bit rate in the same channel bandwidth but also easier to be affected by ingress noises, amplifier compression, and phase noises which degrade the desired service data rate. In order to qualify the cable plant to carry higher QAM signal, a filed unit capable of generating QAM-64 or 128 is used with a test unit at the headend to check the received QAM signal. MER, pre BER, post BER, and Constellation diagram are measured to ensure the return path is properly balanced and free of noise.