A Bistatic Radiometry System for Object Mapping

Kudryashov, V. E.

doi:10.1615/telecomradeng.v77.i20.40

Cited by 4 publications

(1 citation statement)

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“…The ratio of the obtained coherence to a nominal coherence 0.85 [6] is in range of 1.17-1.18 that is useful for VLBI instrument sensitivity. A similar issue is discussed in [10].…”

Section: Fig 12the Measurement Set-up At 1032 Ghzmentioning

confidence: 67%

Laboratory Demonstration of the Local Oscillator Concept for the Event Horizon Imager

Kudriashov

Martín-Neira

Lia

et al. 2021

J. Astron. Instrum.

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Black hole imaging challenges the third-generation space VLBI, the Very Long Baseline Interferometry, to operate on a 500[Formula: see text]GHz band. The coherent integration time needed here is 450[Formula: see text]s though the available space oscillators cannot offer more than 10[Formula: see text]s. Self-calibration methods might solve this issue in an interferometer formed by three antenna/satellite systems, but the need for the third satellite increases the mission costs. A frequency transfer is of special interest to alleviate both performance and cost issues. A concept of two-way optical frequency transfer is examined to investigate its suitability to enable space-to-space interferometry, in particular, to image the “shadows” of black holes from space. The concept, promising on paper, has been demonstrated by tests. The laboratory test set-up is presented and the verification of the temporal stability using standard analysis tool as TimePod has been passed. The resulting Allan Deviation is dominated by the 1/[Formula: see text] phase noise trend since the frequency transfer timescale of interest is shorter than 0.2[Formula: see text]s. This trend continues into longer integration times, as proven by the longest tests spanning over a few hours. The Allan Deviation between derived 103.2[Formula: see text]GHz oscillators is [Formula: see text]/[Formula: see text] within 10[Formula: see text][Formula: see text][Formula: see text]s that degrades twice towards the longest delay of 0.2[Formula: see text]s. The worst case satisfies the requirement with a margin of 11 times. The obtained coherence in the range of 0.997[Formula: see text]0.9998 is beneficial for space VLBI at 557[Formula: see text]GHz. The result is of special interest to future science missions for black hole imaging from space.

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“…The ratio of the obtained coherence to a nominal coherence 0.85 [6] is in range of 1.17-1.18 that is useful for VLBI instrument sensitivity. A similar issue is discussed in [10].…”

Section: Fig 12the Measurement Set-up At 1032 Ghzmentioning

confidence: 67%