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Abstract The increased bandwidth coupled with the large numbers of antennas of several new radio telescope arrays has resulted in an exponential increase in the amount of data that needs to be recorded and processed. In many cases, it is necessary to process this data in real time, as the raw data volumes are too high to be recorded and stored. Due to the ability of GPUs to process data in parallel, GPUs are increasingly used for data-intensive tasks. In most radio astronomy digital instrumentation (e.g., correlators for spectral imaging, beamforming, pulsar, fast radio burst and SETI searching), the processing power of modern GPUs is limited by the input/output data rate, not by the GPU's computation ability. Techniques for streaming ultra-high-rate data to GPUs, such as those described in this paper, reduce the number of GPUs and servers needed, and make significant reductions in the cost, power consumption, size, and complexity of GPU based radio astronomy backends. In this research, we developed and tested several different techniques to stream data from network interface cards (NICs) to GPUs. We also developed an open-source UDP/IPv4 400 GbE wrapper for the AMD/Xilinx IP demonstrating high-speed data stream transfer from a field programmable gate array (FPGA) to GPU. 

Wideband beamforming and interference cancellation for phased array antennas requires advances in signal processing algorithms, software, and specialized hardware platforms. A high-throughput array receiver has been developed that enables communication in radio frequency interference-rich environments with field programmable gate array (FPGA)-based frequency channelization and packetization. In this study, a real-time interference mitigation algorithm was implemented on graphics processing units (GPUs) contained in the data pipeline. The key contribution is a hardware and software pipeline for subchannelized wideband array signal processing with 150 MHz instantaneous bandwidth and interference cancellation with a heterogeneous, distributed, and scaleable digital signal processing (DSP) architecture that achieves 30 dB interferer cancellation null depth in real time with a moving interference source. 

The noise performance of a high sensitivity, wide-field astronomical phased array feed receiver can be characterized by measurements using the antenna Y factor method. These measurements are used to determine figures of merit for an active array receiver. Antenna elements for the Advanced L Band Phased Array Camera for Astronomy (ALPACA) were measured using the antenna Y factor method to determine the active array and receiver noise figure, the antenna loss, receiver equivalent noise temperature, and radiation efficiency of the system over its 500[Formula: see text]MHz operating bandwidth. The completed ALPACA instrument will feature a fully cryogenic design with both the low-noise amplifiers and array elements cryogenically cooled. The uncooled performance measurements from the antenna Y factor method are used to extrapolate the elements cryogenic radiation efficiency and antenna loss showing that it is expected that the elements will contribute less than 1 K to the overall system noise temperature. These results validate the antenna Y factor method to measure key antenna parameters such as the antenna radiation efficiency and show that the instruments front-end array and electronics meets expected performance targets.