4007 DSPFig. 47 Effect of NR1 with the Spectral Subtraction Method● NR1 (Line Enhancer Method)The line enhancer method, which employs a DSP, is widely used for general noise reduction.The line enhancer method automatically changes the FIR filter characteristics according to the frequency components ofthe received signals. It provides high filtering effects particularly for periodic signals such as CW signals to improve theS/N ratio. Because the process automatically passes and emphasizes periodic signals, it is called a line enhancer (lineenhancer method). The line enhancer employs a relatively simple signal processing system to improve the S/N ratio. Atthe same time, however, it also has drawbacks such as blurring the sound when processing weak signals in the SSBmode. It is positioned in the TS-890S as a noise reduction method for non-audio signals.The graphs below show how NR1 improves the S/N ratio of a tone signal with the line enhancer method.Fig. 48 Effect of NR1 with the Line Enhancer Method
