Scientific achievements. Hardware and methodological developments

2025

Method for Fast Radio Burst (FRB) search in RATAN-600 surveys using a convolutional neural network

Since 2017, a search for fast radio bursts (FRBs)—bright short-timescale impulsive events (<1 ms) subject to cosmic dispersion—has been conducted in RATAN-600 surveys of sky regions at different declinations using four four-channel radiometers in the 4.4–5 GHz range. To automate FRB detection, observation records are scanned with a convolutional neural network, whose task is to identify FRBs in the presence of radio frequency interference and high radiometer noise. The neural networks used for 2D image classification, common in worldwide practice, are not applicable to our data due to the lack of a second coordinate (four channels instead of several thousands). Based on the EfficientNet family, we developed our own neural network for classifying multichannel time series using one-dimensional convolutions taking into account the data array's specifics and reducing the number of trainable parameters.

To suppress false positives, a cascaded scheme of two neural networks is used, where the second network is designed to verify candidates provided by the first network. This reduced false positives to the order of 0.0005% (the exact value is adjustable via the probability threshold). Such a low rate is necessary due to the large number of records processed by the network—the scanning process is performed by splitting the time series into one-second segments.

The method is capable of detecting FRB signals even at levels comparable to system noise. The developed neural network can be applied to classify any multichannel time series in other scientific and applied tasks.

The work was performed under the state assignment of SAO RAS.

Authors:
Kudryavtsev D.O., Trushkin S.A., Tsybulev P.G., Stolyarov V.A. (SAO RAS).

Published:
Kudryavtsev D.O., Trushkin S.A., Tsybulev P.G., Stolyarov V.A., Neural networks in the search for fast radio bursts with RATAN-600, Astronomy and Computing, 2026, Volume 54, id. 101002.

Implementation of a New Decimeter Two-Frequency Radiometer Based on a Horn Antenna with a Common Phase Center

At RATAN-600, a decimeter two-frequency radiometer covering 13 cm and 21 cm bands (with 100 MHz bandwidths) was developed and put into round-the-clock observations. Under the SAO RAS technical assignment, a dual-band horn antenna with a shared phase center (by FSUE SKB IRE RAS) and ultra-low-noise amplifiers, bandpass filters, and directional couplers (by the Research and Production company Micran JSC, Tomsk) were developed and designed. The radiometer replaced the previous-generation receivers at 13- and 25-cm wavelengths and enabled observations with the maximum possible sensitivity for an uncooled radiometer, up to 10 mJy in spectral flux density. The implementation increased the number of detectable radio sources several-fold. The radiometer is used in routine observations of compact and extended radio sources, with capabilities for active digital interference mitigation, fast radio-burst searches, 21-cm neutral hydrogen-line spectral observations, pulsars, and more.

The work was carried out within the framework of the state assignment of SAO RAS.

Authors:
Tsybulev P.G., Nizhelsky N.A., Prizov P.V., Kratov D.V., Udovitsky R.Yu., Sotnikova Yu.V., Borisov A.N., Khapaev A.A. (SAO RAS).
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