Frequency independent suppression of interference signals on spread-spectrum communications

A novel device, called the frequency-independent strong-signal suppressor (FISSS), is described. It is placed after the antenna and uses an amplitude-dependent voltage standing wave ratio that exhibits a very sharp transition from matched load to open load. Signals having amplitudes greater than a predetermined threshold (e.g. the interfering signals) are absorbed, while weaker signals (e.g. the spread-spectrum signal) are reflected and extracted by means of a directional coupler. Some laboratory results are described such as the suppression of one or a few CW tones by tens of decibels and the improvement of bit error rate performance of a direct-sequence spread system by tens of decibels. The extension of the FISSS to frequency hopping is described