Development of a real-time transient analyser for the SKA

[摘要] ENGLISH ABSTRACT: The extension of the Karoo Array Telescope (KAT), MeerKAT, will be the most sensitive radio telescope in the southern hemisphere until it is superseded by the completion of the Square Kilometre Array (SKA). These instruments are to be constructed in the Karoo which is an area in South-Africa that is protected against Radio Frequency Interference (RFI) by the Astronomy Geographical Advantage (AGA) act. However, the telescope is also vulnerable to self-generated interference and specialised measurement systems are required to monitor RFI levels. The development of a ReAl Time Transient AnalYser (RATTY) is described and two Experimental Development Models (XDM) are compared. The first uses a mixing philosophy, and the second direct-sampling. The selection of these models was based on the evaluation of several analogue Front-End (FE) designs. A stripline-filter design process is presented along with the results obtained for custom filters developed for the FEs. Several analyses were compared to measurements performed with one of the devices and good agreement was shown between the system characteristics. Issues regarding the Spurious Free Dynamic Range (SFDR) of the FE designs were identified in the process and measurement-corrected simulations used to predict the achievable ranges. The outcome of the XDM comparison promotes the continued development of a direct-sampling strategy to fulfil the short-term goals of the project. A static calibration procedure is demonstrated for the mixing system and implemented to account for different FE configurations. An overview of the digital and software components of the RATTY system is given and Electromagnetic Compatibility (EMC) principles are applied during the construction of both systems.

[发布机构] Stellenbosch University