Burst-Mode Synchronization for SOQPSK (SYNC)
Project Award Date: 09-09-2011
For a communication link to be functional, synchronization between the transmitter and receiver is required. By synchronization, ITTC researchers mean carrier frequency synchronization, carrier phase synchronization, and symbol timing synchronization. One key difference between the future architecture for telemetry, integrated Network Enhanced Telemetry (iNET), and the existing architecture for telemetry, Serial Streaming Telemetry (SST), is that iNET transmits data packets in bursts, whereas SST transmits data packets in long continuous transmissions. This key difference has large implications on how the telemetry receiver is synchronized with the telemetry transmitter. The burst-mode receiver must deal with transmissions that are relatively short and independent of one another. Therefore, the receiver must start from scratch when it acquires and synchronizes each burst. Because the transmission is brief, PLL-based approaches do not have enough time to acquire the signal (to be more precise, a significant fraction of the payload will be lost during the time that the PLL is locking onto the signal.) A synchronization preamble is required in order to achieve rapid synchronization in burst-mode communications.
ITTC researchers will examine the theoretical limits as to how well the synchronization parameters can be estimated for burst-mode communications of Shaped Offset Quadrature Phase Shift Keying (SOQPSK-TG). They will determine which preamble sequence provides the optimal estimation accuracy, and how many bits must be devoted to the preamble so that the receiver can synchronize at low Signal-to-Noise Ratios (SNRs). After answering these questions, researchers will design practical synchronization algorithms that approach the theoretical performance limits and implement these algorithms into a hardware prototype. These efforts support the ongoing migration to iNET.
Primary Sponsor(s): Department of Defense