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Transactions of IAA RAS, issue 46, 19–30 (2018)

Keywords: radio interferometer, VLBI, tri-band receiver, wideband receiver, local oscillator, correlator, signal-to-noise ratio, delay, phase stability, delay stability.

### Abstract

A prototype of a zero-baseline VLBI testbed has been designed in the IAA RAS to analyze characteristics of radio astronomical receivers. It includes a tunable noise generator, a 512 MHz bandwidth broadband data acquisition system, a frequency standard, a data transmission system, and the RASFX correlator. This paper presents the VLBI testbed and the results of using it in X-band with two tri-band receivers and one wide-band receiver prototype. The following correlation response characteristics have been obtained: signal-to-noise ratio, delay rate, and phase and delay stability. We have analysed the influence of inaccuracies in the frequency setup and phase instabilities of heterodynes in the receivers on the response characteristics of the zero-baseline radio interferometer. It is shown that the digital filtering of signal spectra reduces the RMSD (Root-mean-square deviation) of the measured delays. The anti-aliasing filter characteristics of the zerobaseline radio interferometer which can minimise the influence of the receiver phase instability on the RMSD of the measured delays, are proposed using mathematical simulation.

### Citation

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Y. V. Vekshin, V. O. Ken, V. K. Chernov, A. A. Evstigneev. Research of the Receivers Characteristics Using a Radio Interferometric Testbed // Transactions of IAA RAS. — 2018. — Issue 46. — P. 19–30. @article{vekshin2018, abstract = {A prototype of a zero-baseline VLBI testbed has been designed in the IAA RAS to analyze characteristics of radio astronomical receivers. It includes a tunable noise generator, a 512 MHz bandwidth broadband data acquisition system, a frequency standard, a data transmission system, and the RASFX correlator. This paper presents the VLBI testbed and the results of using it in X-band with two tri-band receivers and one wide-band receiver prototype. The following correlation response characteristics have been obtained: signal-to-noise ratio, delay rate, and phase and delay stability. We have analysed the influence of inaccuracies in the frequency setup and phase instabilities of heterodynes in the receivers on the response characteristics of the zero-baseline radio interferometer. It is shown that the digital filtering of signal spectra reduces the RMSD (Root-mean-square deviation) of the measured delays. The anti-aliasing filter characteristics of the zerobaseline radio interferometer which can minimise the influence of the receiver phase instability on the RMSD of the measured delays, are proposed using mathematical simulation.}, author = {Y.~V. Vekshin and V.~O. Ken and V.~K. Chernov and A.~A. Evstigneev}, doi = {10.32876/ApplAstron.46.19-30}, issue = {46}, journal = {Transactions of IAA RAS}, keyword = {radio interferometer, VLBI, tri-band receiver, wideband receiver, local oscillator, correlator, signal-to-noise ratio, delay, phase stability, delay stability}, pages = {19--30}, title = {Research of the Receivers Characteristics Using a Radio Interferometric Testbed}, url = {http://iaaras.ru/en/library/paper/1872/}, year = {2018} } TY - JOUR TI - Research of the Receivers Characteristics Using a Radio Interferometric Testbed AU - Vekshin, Y. V. AU - Ken, V. O. AU - Chernov, V. K. AU - Evstigneev, A. A. PY - 2018 T2 - Transactions of IAA RAS IS - 46 SP - 19 AB - A prototype of a zero-baseline VLBI testbed has been designed in the IAA RAS to analyze characteristics of radio astronomical receivers. It includes a tunable noise generator, a 512 MHz bandwidth broadband data acquisition system, a frequency standard, a data transmission system, and the RASFX correlator. This paper presents the VLBI testbed and the results of using it in X-band with two tri-band receivers and one wide-band receiver prototype. The following correlation response characteristics have been obtained: signal-to- noise ratio, delay rate, and phase and delay stability. We have analysed the influence of inaccuracies in the frequency setup and phase instabilities of heterodynes in the receivers on the response characteristics of the zero-baseline radio interferometer. It is shown that the digital filtering of signal spectra reduces the RMSD (Root-mean-square deviation) of the measured delays. The anti- aliasing filter characteristics of the zerobaseline radio interferometer which can minimise the influence of the receiver phase instability on the RMSD of the measured delays, are proposed using mathematical simulation. DO - 10.32876/ApplAstron.46.19-30 UR - http://iaaras.ru/en/library/paper/1872/ ER -