Wideband RF downconverters for digital telemetry receivers

Summary form only given, as follows. The development of extremely high sampling rate, high dynamic range A/D converters has resulted in the feasibility of a mostly digital telemetry receiver. The Naval Command and Control and Ocean Surveillance Center, under Office of Navy Research funding is developing an advanced ASW receiver which implements RF channel filtering and null steering direction finding and information demodulation in a high speed digital signal processor. This paper describes the analysis conducted for the analog RF circuitry required to downconvert the multichannel VHF sonobuoy band to baseband compatible with current technology A/D components. The performance parameters critical to the system design include good spurious free performance, sharp band edge filtering and an AGC scheme which permits phase and amplitude match between antenna input channels. The paper discusses the analysis tradeoffs performed to arrive at the downconverter design, and includes a discussion of the components selected for the receiver hardware implementation as well as the component mounting and shielding techniques