Progress on Analogue Front end for 2PAD

Abstract

The medium of RF signal transfer adopted for 2PAD was twisted pair differential signal cabling. While intended to demonstrate a low cost solution, the technique has brought with it several challenges, not least in terms of the losses and phase skew introduced. Some interesting engineering challenges have been faced along the way to delivering usable signals to the DSP Engineers. Faced with an aggressive RFI environment, with strong TV and GSM broadcast signals, a small, reasonably quiet band was exploited. A review of the RFI shielding policy has been required to maintain stability in the gain stages of the analogue system. An effective cabinet RFI barrier has been successfully demonstrated. Future work through PrepSKA will explore alternative cabling solutions, such as coaxial and optical fibre, with the intention of evaluating the main contenders against the cost, power, and performance requirements for SKA.

A quantitative analysis of how phase errors affect the beam quality of phased arrays

“…We describe how we used OSKAR to generate array beam profiles from a number of aperture arrays of different sizes, each with different phase errors on each analogue signal chain. Finally, in Section 4, we discuss the performance that could practically be achieved for aperture arrays of various sizes using either analogue or digital beam forming engines if the array were constructed using the same analogue components as currently used in 2-PAD [5,6]. …”