A single-chip narrow-band frequency-domain excisor for a Global Positioning System (GPS) receiver

In recent gears, we have witnessed the rapid adoption of the Department of Defense´s Global Positioning System (GPS) for navigation in a number of military and civilian applications. Unfortunately, the low-power GPS signal is susceptible to interference. This paper presents a novel VLSI architecture that removes narrow-band signals from the wide-bandwidth GPS spectrum. The interference suppression technique employed is frequency-domain excision. The single-chip frequency-domain excisor transforms the received signal (GPS signal+noise+interference) to the frequency domain, computes signal statistics to determine an excision threshold, removes all spectral energy exceeding that threshold, and restores the remaining signal (GPS signal+noise) to the temporal domain. The heart of this VLSI implementation is an on-chip 256-point fast Fourier transform processor that operates at 40 million complex samples per second. It processes 12-bit (for each I and Q) sampled complex data. The 1.57 million-transistor chip was fabricated in 0.5-/spl mu/m CMOS triple metal technology and is fully functional.