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