Design And Implementation Of Noise Monitoring System Of HFC Reverse Channel Based On DSP

HFC duplex transmission systems is a novel network transmission mode, which develop rapidly with the demand for value-added services of CATV and enables television transmission network system transformed fully from simplex into duplex. With the large-scale development and update of the HFC networks, broadband data services of HFC network become a priority cause for users to choice broadband. But in the HFC network carrying communications business, the transmission quality of reverse channel must be at first, which is primary affect by the noise aggregation and intrusive interference in the up bound of HFC duplex systems.For noise aggregation and intrusive interference in the reverse channel of HFC network, design and implementation of a real-time signal spectrum monitoring system based on Digital Signal Processor (DSP) and Ethernet network structure is proposed in this paper. A multi-channel high-speed data acquisition system has been proposed for the RF input signal to achieve high dynamic range and low noise digital convert performances; Adopting the high-speed data-processing DSP capability, the time-varying RF signals were analyzed in many fields; Through ARM chip framework Ethernet communications system, great quantity and distributed networks channel are real-time monitored, and for timely detection and analysis. Noise suppression system based on the SPDT composed of a set of new HFC reverse channel noise monitoring and suppression solutions, real-time monitoring HFC reverse channel noise, control HFC upstream convergence of the slip road and reduce uplink noise convergence by means of noise suppression system.In this paper, the details of various hardware circuits have be given. Several key issues in hardware design have been solved and a complete physical system has been fabricated and test. Experimental results demonstrate that the given system has received perfect performance in maintenance of reverse channel.HFC reverse channel noise monitoring system protect reverse channel in CATV network, assured reliable upstream data transmission and provides technical support to interactive digital television broadcasting business extension.