Receiver systems in radio astronomy consist of a number of components, starting with the antenna, via a number of discrete electronic components to the digital electronic boards. The technology development towards Compact Receiver systems aims to integrate these components and lower the overall cost of the telescope’s frontend technology.
Internet of things
In the internet of things, small antennas and electronic components are required in almost all equipment. The integration to compact receiver systems as we pursue is extremely relevant to trend in society towards smart homes, smart grids, smart cities and smart society.
From separated parts to a completely integrated solution
In most radio astronomical frontends of today, the analog, digital and optoelectronic parts are still separated. As a result, components with different, stand-alone designs are combined into a telescope frontend. While this approach was very successful in the past, we are facing a practical and economic problem if the number of elements in the radio telescope is increasing substantially, like in the case of the SKA telescope. Also, the benefits of complete system integration are not fully exploited if the parts in the frontend are separated. Especially the interconnections between the parts can be dominant sources of failures, gain-frequency dependencies and phase instabilities in the receiver chain. Our efforts therefore focus on the development a completely integrated solution, the Compact Receiver system.
In addition, the use of an antenna remoting approach in the telescope architecture, i.e. concentrating the telescope functionality (hardware) at a central location, gets more-and-more attractive as it provides the lowest operational costs and the largest functionality for the astronomer. The currently applied (analog) signal transport techniques in the telescope front-end do not fully support the antenna remoting approach due to limitations in the transmission distance, dynamic range and RF phase stability. To remove these limitations, we intend to apply digitization at the antenna.
The Compact Receiver approach focusses on integrating technologies in the analog/digital electronic, electronic/photonic and mechanical domains. The functionalities provided by these domains cover the complete signal path in the telescope front-end up to the central signal processor of a telescope.
Sensitive and stable receivers
Since celestial radio waves are mostly very weak signals, large antennas and extremely sensitive and stable receivers are required. At the same time, these systems should be robust against the increasing man-made radio interference, caused by the boost in mobile broadband connectivity and navigation systems.
Electronic technology is used for transfer and processing of the received signals. This often requires innovative technologies as the data rates are very high. For example, the application of photonic technology in data transport and processing is attractive thanks to its excellent performance in broad bandwidths. Integrating technologies in the analog, digital, electronic, photonic, and mechanical domains is an important development towards our future telescopes as this will lead to more compact systems and will reduce power consumption and cost.
The mechanical properties of the equipment in the field is important as well. Design for robustness including thermal, humidity, and irradiance, ensures a long lifetime in harsh environmental conditions. Design for high wind loads and other environmental conditions should ensure a high accuracy of the instrument under all circumstances.
A challenging factor in the design of large sensor systems is the high quality – low-cost/high-volume requirement. A close and good interaction with a variety of industries is crucial to prepare for mass production of components by industry.
The data from all antennas are combined in dedicated high performance supercomputers using the newest energy efficient accelerator technologies. Calibration algorithms are applied to correct for instrumental effects but also to correct ionospheric distortions. Imaging algorithms applied in pipelines produce high quality image cubes that allow astronomers to do their revolutionary science. The data is archived in open science clouds allowing reuse and increasing science output.