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 <front>
  <journal-meta>
   <journal-id journal-id-type="publisher-id">Solar-Terrestrial Physics</journal-id>
   <journal-title-group>
    <journal-title xml:lang="en">Solar-Terrestrial Physics</journal-title>
    <trans-title-group xml:lang="ru">
     <trans-title>Solar-Terrestrial Physics</trans-title>
    </trans-title-group>
   </journal-title-group>
   <issn publication-format="online">2500-0535</issn>
  </journal-meta>
  <article-meta>
   <article-id pub-id-type="publisher-id">43288</article-id>
   <article-id pub-id-type="doi">10.12737/stp-74202110</article-id>
   <article-categories>
    <subj-group subj-group-type="toc-heading" xml:lang="ru">
     <subject>Results of current research</subject>
    </subj-group>
    <subj-group subj-group-type="toc-heading" xml:lang="en">
     <subject>Results of current research</subject>
    </subj-group>
    <subj-group>
     <subject>Results of current research</subject>
    </subj-group>
   </article-categories>
   <title-group>
    <article-title xml:lang="en">Measurement of Siberian Radioheliograph cable delays</article-title>
    <trans-title-group xml:lang="ru">
     <trans-title>Measurement of Siberian Radioheliograph cable delays</trans-title>
    </trans-title-group>
   </title-group>
   <contrib-group content-type="authors">
    <contrib contrib-type="author">
     <contrib-id contrib-id-type="orcid">https://orcid.org/0009-0004-1651-1259</contrib-id>
     <name-alternatives>
      <name xml:lang="ru">
       <surname>Лесовой</surname>
       <given-names>Сергей Владимирович</given-names>
      </name>
      <name xml:lang="en">
       <surname>Lesovoi</surname>
       <given-names>Sergey Vladimirovich</given-names>
      </name>
     </name-alternatives>
     <email>lesovoi@iszf.irk.ru</email>
     <bio xml:lang="ru">
      <p>кандидат физико-математических наук;</p>
     </bio>
     <bio xml:lang="en">
      <p>candidate of physical and mathematical sciences;</p>
     </bio>
     <xref ref-type="aff" rid="aff-1"/>
    </contrib>
    <contrib contrib-type="author">
     <contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-9174-7350</contrib-id>
     <name-alternatives>
      <name xml:lang="ru">
       <surname>Глоба</surname>
       <given-names>Мария Викторовна</given-names>
      </name>
      <name xml:lang="en">
       <surname>Globa</surname>
       <given-names>Mariia Viktorovna</given-names>
      </name>
     </name-alternatives>
     <email>globa@iszf.irk.ru</email>
     <bio xml:lang="ru">
      <p>аспирант физико-математических наук;</p>
     </bio>
     <bio xml:lang="en">
      <p>graduate student of physical and mathematical sciences;</p>
     </bio>
     <xref ref-type="aff" rid="aff-2"/>
    </contrib>
   </contrib-group>
   <aff-alternatives id="aff-1">
    <aff>
     <institution xml:lang="ru">Институт солнечно-земной физики СО РАН</institution>
     <city>Иркутск</city>
     <country>Россия</country>
    </aff>
    <aff>
     <institution xml:lang="en">Institute of Solar Terrestrial Physics SB RAS</institution>
     <city>Irkutsk</city>
     <country>Russian Federation</country>
    </aff>
   </aff-alternatives>
   <aff-alternatives id="aff-2">
    <aff>
     <institution xml:lang="ru">Институт солнечно-земной физики СО РАН</institution>
     <city>Иркутск</city>
     <country>Россия</country>
    </aff>
    <aff>
     <institution xml:lang="en">Institute of Solar Terrestrial Physics SB RAS</institution>
     <city>Irkutsk</city>
     <country>Russian Federation</country>
    </aff>
   </aff-alternatives>
   <pub-date publication-format="print" date-type="pub" iso-8601-date="2021-12-20T00:00:00+03:00">
    <day>20</day>
    <month>12</month>
    <year>2021</year>
   </pub-date>
   <pub-date publication-format="electronic" date-type="pub" iso-8601-date="2021-12-20T00:00:00+03:00">
    <day>20</day>
    <month>12</month>
    <year>2021</year>
   </pub-date>
   <volume>7</volume>
   <issue>4</issue>
   <fpage>93</fpage>
   <lpage>97</lpage>
   <history>
    <date date-type="received" iso-8601-date="2021-04-06T00:00:00+03:00">
     <day>06</day>
     <month>04</month>
     <year>2021</year>
    </date>
    <date date-type="accepted" iso-8601-date="2021-08-12T00:00:00+03:00">
     <day>12</day>
     <month>08</month>
     <year>2021</year>
    </date>
   </history>
   <self-uri xlink:href="https://naukaru.ru/en/nauka/article/43288/view">https://naukaru.ru/en/nauka/article/43288/view</self-uri>
   <abstract xml:lang="ru">
    <p>To achieve the maximum dynamic range of solar radio images obtained using aperture synthesis in relatively wide frequency bands 0.1−0.5 % of the operating frequency, it is necessary to compensate the signal propagation delays in the antenna receive path before calculating visibility functions (hereinafter visibilities). When visibilities are corrected without delay compensation, the signal-to-noise ratio decreases due to residual phase slopes in the receiving system bandwidth. In addition to enhancing dynamic range, preliminary compensation for delays simplifies real-time imaging — no antenna gain calibration is required to get a first approximation image. The requirements for the accuracy of antenna placement are also reduced — in contrast to the measurement of the phase visibility error, the measurement of the delay is actually not so critical to the antenna position errors that are larger than the operating wavelength. The instantaneous frequency band of the Siberian Radioheliograph, which determines the minimum step for measuring the phase slope, and hence the accuracy of determining the delay, is 10 MHz. At the speed of light in an optical fiber of ~0.7c, a step of 10 MHz makes it possible to unambiguously measure the difference between electrical lengths of cables up to 20 m and to correct antenna positions by radio observations, even if the error in the position of the antennas exceeds the operating wavelength. Correction of the band phase slopes during the observation time adapts the radio telescope to the temperature drift of delays and decreases antenna gain phase spread. This, in turn, leads to more stable solutions to systems of equations containing antenna gains as unknowns.</p>
   </abstract>
   <trans-abstract xml:lang="en">
    <p>To achieve the maximum dynamic range of solar radio images obtained using aperture synthesis in relatively wide frequency bands 0.1−0.5 % of the operating frequency, it is necessary to compensate the signal propagation delays in the antenna receive path before calculating visibility functions (hereinafter visibilities). When visibilities are corrected without delay compensation, the signal-to-noise ratio decreases due to residual phase slopes in the receiving system bandwidth. In addition to enhancing dynamic range, preliminary compensation for delays simplifies real-time imaging — no antenna gain calibration is required to get a first approximation image. The requirements for the accuracy of antenna placement are also reduced — in contrast to the measurement of the phase visibility error, the measurement of the delay is actually not so critical to the antenna position errors that are larger than the operating wavelength. The instantaneous frequency band of the Siberian Radioheliograph, which determines the minimum step for measuring the phase slope, and hence the accuracy of determining the delay, is 10 MHz. At the speed of light in an optical fiber of ~0.7c, a step of 10 MHz makes it possible to unambiguously measure the difference between electrical lengths of cables up to 20 m and to correct antenna positions by radio observations, even if the error in the position of the antennas exceeds the operating wavelength. Correction of the band phase slopes during the observation time adapts the radio telescope to the temperature drift of delays and decreases antenna gain phase spread. This, in turn, leads to more stable solutions to systems of equations containing antenna gains as unknowns.</p>
   </trans-abstract>
   <kwd-group xml:lang="ru">
    <kwd>radio telescope</kwd>
    <kwd>aperture synthesis</kwd>
    <kwd>radio image</kwd>
   </kwd-group>
   <kwd-group xml:lang="en">
    <kwd>radio telescope</kwd>
    <kwd>aperture synthesis</kwd>
    <kwd>radio image</kwd>
   </kwd-group>
   <funding-group>
    <funding-statement xml:lang="ru">The work was performed under Government Assignment for 2021 No. 075-00374-21-00 dated December 24, 2020 &quot;Methods and Instruments of an Astrophysical Experiment&quot; (unique number 0278-2021-0010, registration number CITiS 121040600115-2)</funding-statement>
    <funding-statement xml:lang="en">The work was performed under Government Assignment for 2021 No. 075-00374-21-00 dated December 24, 2020 &quot;Methods and Instruments of an Astrophysical Experiment&quot; (unique number 0278-2021-0010, registration number CITiS 121040600115-2)</funding-statement>
   </funding-group>
  </article-meta>
 </front>
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  <ref-list>
   <ref id="B1">
    <label>1.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">Altyntsev A.T., Lesovoi S.V., Globa M.V., Gubin A.V., Kochanov A.A., Grechnev V.V., et al. Multiwave Siberian Radioheliograph. Solar-Terr. Phys. 2020, vol. 6, iss. 2, pp. 30-40. DOI: 10.12737/stp-62202003.</mixed-citation>
     <mixed-citation xml:lang="en">Altyntsev A.T., Lesovoi S.V., Globa M.V., Gubin A.V., Kochanov A.A., Grechnev V.V., et al. Multiwave Siberian Radioheliograph. Solar-Terr. Phys. 2020, vol. 6, iss. 2, pp. 30-40. DOI: 10.12737/stp-62202003.</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B2">
    <label>2.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">Cornwell T., Fomalont E.B. Self-calibration. Synthesis imaging in radio astronomy. A collection of Lectures from the Third NRAO Synthesis Imaging Summer School. Astronomical Society of the Pacific Publ., 1989, vol. 6, p. 185.</mixed-citation>
     <mixed-citation xml:lang="en">Cornwell T., Fomalont E.B. Self-calibration. Synthesis imaging in radio astronomy. A collection of Lectures from the Third NRAO Synthesis Imaging Summer School. Astronomical Society of the Pacific Publ., 1989, vol. 6, p. 185.</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B3">
    <label>3.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">Hartog A.H., Conduit A.J., Payne D.N. Variation of pulse delay with stress and temperature in jacketed and unjacketed optical fibres. Optical and Quantum Electronics. 1979, vol. 11, pp. 265-273 DOI: 10.1007/BF00620112.</mixed-citation>
     <mixed-citation xml:lang="en">Hartog A.H., Conduit A.J., Payne D.N. Variation of pulse delay with stress and temperature in jacketed and unjacketed optical fibres. Optical and Quantum Electronics. 1979, vol. 11, pp. 265-273 DOI: 10.1007/BF00620112.</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B4">
    <label>4.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">Lesovoi S.V., Altyntsev A.T., Ivanov E.F. Gubin A.V. The Multifrequency Siberian Radioheliograph. Solar Phys. 2012, vol. 280, iss. 2, рр. 651-661. DOI: 10.1007/s11207-012- 0008-7.</mixed-citation>
     <mixed-citation xml:lang="en">Lesovoi S.V., Altyntsev A.T., Ivanov E.F. Gubin A.V. The Multifrequency Siberian Radioheliograph. Solar Phys. 2012, vol. 280, iss. 2, rr. 651-661. DOI: 10.1007/s11207-012- 0008-7.</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B5">
    <label>5.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">Lesovoi S.V., Altyntsev A.T., Kochanov A.A., Grechnev A.A., Gubin A.V., Zhdanov D.A., et al. Siberian Radioheliograph: first results. Solar-Terr. Phys. 2017, vol. 3, iss. 1, pp. 3-18. DOI: 10.12737/article_58f 96ec60fec52.86165286.</mixed-citation>
     <mixed-citation xml:lang="en">Lesovoi S.V., Altyntsev A.T., Kochanov A.A., Grechnev A.A., Gubin A.V., Zhdanov D.A., et al. Siberian Radioheliograph: first results. Solar-Terr. Phys. 2017, vol. 3, iss. 1, pp. 3-18. DOI: 10.12737/article_58f 96ec60fec52.86165286.</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B6">
    <label>6.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">Liu A., Tegmark M., Morrison S. Lutomirski A., Zaldarriaga M. Precision Calibration of Radio Interferometers Using Redundant Baselines. 2010. arXiv: 1001.5268 DOI: 10.1111/ j.1365-2966.2010.17174.x.</mixed-citation>
     <mixed-citation xml:lang="en">Liu A., Tegmark M., Morrison S. Lutomirski A., Zaldarriaga M. Precision Calibration of Radio Interferometers Using Redundant Baselines. 2010. arXiv: 1001.5268 DOI: 10.1111/ j.1365-2966.2010.17174.x.</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B7">
    <label>7.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">Perley R.A. High dynamic range imaging. Synthesis Imaging in Radio Astronomy II. A Collection of Lectures from the Sixth NRAO/NMIMT Synthesis Imaging Summer School. ASP Conference Ser. 1999. Vol. 180. P. 275. DOI: 1999ASPC..180..275P.</mixed-citation>
     <mixed-citation xml:lang="en">Perley R.A. High dynamic range imaging. Synthesis Imaging in Radio Astronomy II. A Collection of Lectures from the Sixth NRAO/NMIMT Synthesis Imaging Summer School. ASP Conference Ser. 1999. Vol. 180. P. 275. DOI: 1999ASPC..180..275P.</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B8">
    <label>8.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">Thompson A.R. Delay tracking, fringe rotation, and phase switching in FASR. FASR memo. 2007.</mixed-citation>
     <mixed-citation xml:lang="en">Thompson A.R. Delay tracking, fringe rotation, and phase switching in FASR. FASR memo. 2007.</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B9">
    <label>9.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">Thompson A.R., Moran J.M., Swenson Jr. G.W. Interferometry and Synthesis in Radio Astronomy. Third Edition. Springer, 2017. DOI: 10.1007/978-3-319-44431-4.</mixed-citation>
     <mixed-citation xml:lang="en">Thompson A.R., Moran J.M., Swenson Jr. G.W. Interferometry and Synthesis in Radio Astronomy. Third Edition. Springer, 2017. DOI: 10.1007/978-3-319-44431-4.</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B10">
    <label>10.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">Walker R.C. Very Long Baseline Interferometry. Synthesis Imaging in Radio Astronomy II. A Collection of Lectures from the Sixth NRAO/NMIMT Synthesis Imaging Summer School. ASP Conference Ser. 1999, vol. 180, р. 433.</mixed-citation>
     <mixed-citation xml:lang="en">Walker R.C. Very Long Baseline Interferometry. Synthesis Imaging in Radio Astronomy II. A Collection of Lectures from the Sixth NRAO/NMIMT Synthesis Imaging Summer School. ASP Conference Ser. 1999, vol. 180, r. 433.</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B11">
    <label>11.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">URL: http://www.ovsa.njit.edu/wiki/index.php/Calibration_Overview (accessed March 20, 2021).</mixed-citation>
     <mixed-citation xml:lang="en">URL: http://www.ovsa.njit.edu/wiki/index.php/Calibration_Overview (accessed March 20, 2021).</mixed-citation>
    </citation-alternatives>
   </ref>
   <ref id="B12">
    <label>12.</label>
    <citation-alternatives>
     <mixed-citation xml:lang="ru">URL: ftp://ftp.rao.istp.ac.ru/SRH/FASR/Thompson_Delay_Fringe_Phsw.pdf (accessed March 20, 2021).</mixed-citation>
     <mixed-citation xml:lang="en">URL: ftp://ftp.rao.istp.ac.ru/SRH/FASR/Thompson_Delay_Fringe_Phsw.pdf (accessed March 20, 2021).</mixed-citation>
    </citation-alternatives>
   </ref>
  </ref-list>
 </back>
</article>
