A Broadband Spectral Analyzer of Cosmic Radio Emissions

Grenkov, S. A.; Kol’tsov, N. E.

doi:10.1134/s0020441219040171

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…Until 2015, the network consisted of three 32-meter radio telescopes (RT-32) located in Svetloe, Zelenchukskaya and Badary observatories [2]. The backends of RT-32 include various devices for single-dish observations, mostly radiometric and spectral ones [3][4][5], and VLBI backend R1002M DAS [6], that supports 16 frequency channels with up to 32 MHz bandwidth each and the total output data rate of 2 Gbps. The R1002M DAS allows Quasar VLBI network stations to participate in international VLBI observations within the International VLBI Service (IVS) [7] and the European VLBI Network (EVN) [8], but neither the antenna nor the backend of RT-32 meet the requirements of the actively growing VLBI Global Observing System (VGOS), which is the new global VLBI infrastructure [9].…”

Section: Introductionmentioning

confidence: 99%

Multifunctional Digital Backend for Quasar VLBI network

Nosov¹,

Marshalov²,

Fedotov³

et al. 2021

J. Inst.

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The new 13-meters radio telescope recently built at Svetloe observatory (Russia) required a backend device that could digitize wideband signals from the receiving system, process the signal appropriately, prepare and transmit the resulting signal to the recorder. The previously existing backends, also used at other radio telescopes of Quasar VLBI network, could not provide compatibility with VGOS (VLBI Global Observing System) requirements. We developed Multifunctional Digital Backend (MDBE) with superior performance, flexibility and functions to equip the new antenna and other radio telescopes of the network with the same backend compatible with both domestic and international systems. The MDBE contains up to 12 input channels with 2 GHz bandwidth, powerful and remotely configurable Field programmable gate arrays (FPGA) for digital signal processing, and optical transceivers with total throughput of 50 Gbps per channel. The digital downconverters implemented in FPGA can form sub channels with 0.5, 2, 4, 8, 16, and 32 MHz bandwidth freely tuned with 10 kHz step. In wideband mode a single channel with 512, 1024 or full 2048 MHz bandwidth can be recorded. The MDBE also supports single-dish applications, such as radiometric and spectrometric observations. The paper presents the results of hardware and firmware development of the system, and the experimental results received with the MDBE in Svetloe observatory.

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Section: Introductionmentioning

confidence: 99%

Multifunctional Digital Backend for Quasar VLBI network

Nosov¹,

Marshalov²,

Fedotov³

et al. 2021

J. Inst.

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“…2. System for extracting narrowband signals from a digital IF signal использовании гетеродинов с тактовой частотой 512 МГц[22] диапазон перестройки ЦВК расширяется до 256 МГц, но и в этом случае необходима предварительная фильтрация входного широкополосного сигнала.…”

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Comparison of Radio Interferometers with Analog and Digital Extraction of Recorded Signal

Kol’tsov¹,

Grenkov²,

Fedotov³

2020

Izv. vysš. učebn. zaved. Ross., Radioèlektron.

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Introduction. Radio telescopes of Very Long Baseline Interferometry (VLBI) networks usually record several signals with relatively narrow (up to 32 MHz) bands, which are extracted by means of base band converters (BBC) from an analog noise signal of an intermediate frequency (IF) with bands up to 1 GHz. When processing data, frequency band synthesis is used. At new small radio telescopes (for example, RT-13), directly wideband IF signals are digitized. An ability to connect the RT-13 radio telescope to the “Quasar” VLBI complex and to international VLBI networks provides by a digital narrow-band signal extraction module developed in 2019.Aim. Determining the measuring accuracy of an interferometric group delay of a signal by a radio interferometer with a digital narrow-band signal extraction module and comparing the sensitivity of interferometers with analog and digital signal extraction systems.Materials and methods. Sensitivity losses of interferometers with different systems for detecting recorded signals were calculated. The accuracy of a multi-channel interferometer with the synthesis of a frequency band and of an interferometer with recording of digital broadband IF signals without band synthesis was compared. The results were confirmed by VLBI observations in the observatories of the “Quasar” complex.Results. When replacing the analog system of signal extraction with digital system the sensitivity losses of the interferometer were slightly reduced. The measurement accuracy of the interferometric group delay had not changed. Accuracy increased when digitally recording broadband IF signals and when synthesizing a frequency band significantly larger than the IF bandwidth. Conditions and minimum synthesized bands were determined under which the accuracy of the interferometer with the registration of narrowband signals can be higher than the accuracy of the interferometer with the registration of wideband IF signals.Conclusion. The problem of combining RT-13 radio telescopes with VLBI networks with recording of video frequency signals was solved. The efficiency of the installation of digital signal conversion systems at radio telescopes was shown.

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A Backend System for Registering Narrowband Cosmic Radio Emissions

Grenkov

Kol’tsov

2020

Instrum Exp Tech

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A Broadband Spectral Analyzer of Cosmic Radio Emissions

Cited by 3 publications

References 5 publications

Multifunctional Digital Backend for Quasar VLBI network

Multifunctional Digital Backend for Quasar VLBI network

Comparison of Radio Interferometers with Analog and Digital Extraction of Recorded Signal

A Backend System for Registering Narrowband Cosmic Radio Emissions

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