SYSTEM AND METHOD FOR RE-SYNCHRONIZING A PHASE-INDEPENDENT FIRST-IN FIRST-OUT MEMORY

摘要

A re-synchronizing phase-independent first-in first-out (FIFO) memory (902) aligns digital data transmitted between receive shelves (408, 410, 412, 414) and digital shelves (702, 704, 706, 708) in the gateway transceiver subsystem (GTS) of a low orbit (LEO) satellite system. RF data transmitted from an LEO satellite (110, 112) is segmented into multiple receive shelves (408, 410, 412, 414) designed to filter and sample a large volume of information. The receive shelves (408, 410, 412, 414) filter the data, down convert the data to an IF frequency range and clock the data into the digital shelves (702, 704, 706, 708), where demodulator ASICs demodulate the data to retrieve an original signal sent by a mobile radio-telephone user. The re-synchronizing phase-independent FIFO memory (902, 904, 906, 908) uses separate input clock (CLK_IN) signals (712b) and input synchronization (EVEN_SEC) signals (712a) to align data leaving the receive shelves (408, 410, 412, 414). It also uses an independent timed output clock (CLK_OUT) signal (910b) and an independent output synchronization (SYNC_OUT) signal (910a) to align the same data as it goes into the digital shelves (702, 704, 706, 708). This prevents the isochronous (same frequency) signals from being phase misaligned due to disadvantageous Doppler effects or component characteristics.