Signal Recording System of the Multibeam LPA Radio Telescope at the PRAO ASC LPI

Abstract

A multichannel signal recording system (MSRS) developed for the 128-beam LPA radio telescope of PRAO ASC LPI is described. The signals coming from the radio telescope are RF signals in the frequency range of 0–115 MHz with a 2.5-MHz-wide telescope operating band located in the range of 109.0–111.5 MHz. Digitization of each signal is carried out by direct sampling at a frequency of 230 MHz with further fully digital signal processing. Processing includes transfer of the operating band towards the low-frequency region, suppression of the signal outside the operating band, and division of the useful signal into 512 spectral channels using a complex Fourier processor. All processing is performed on the basis of field-programmable gate arrays located on base modules that were specially developed by PRAO and placed in slots of industrial computers. The spectrum sequences are then transferred to the computer RAM for the recording program and then are written in a required format on a hard disk. The use of the combined hardware and software processing has made it possible to develop a compact, reliable, and inexpensive recording system. The MSRS created specifically for the LPA radio telescope is unique.