Design and analysis methods of a DDS-based synthesizer for military spaceborne applications

Abstract

Modern wideband, multi-user antijam communication systems typically employ frequency hopping techniques to maximize system processing gains. Such frequency plans place strict constraints on the hopping LO in the form of spurious, phase noise, and transient response criteria. Historically, synthesizer designers have relied on phase lock techniques to meet these demands. However, the demand for compact satellite communications payloads, with reduced size, weight, power, and cost, is revealing the direct-digital synthesizer (DDS) as the next-generation synthesizer workhorse. To date, application specific integrated circuit (ASIC) development has not progressed sufficiently to accommodate the clock rates and edge speeds necessary for DDS compliance with military satellite communication (MLLSATCOM) specifications. Original design and analysis methods are therefore required to employ the DDS, at the expense of hardware complexity. This paper discusses the translation of a low frequency, narrowband DDS spectrum to a Ku-band, 1 GHz bandwidth (BW) output that meets the strict spurious, phase noise, and transient specifications required of MILSATCOM spacecraft payloads.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>