Spectral-line analysis of very-long-baseline interferometric data

Moran, J. M.

doi:10.1109/proc.1973.9252

Cited by 20 publications

(6 citation statements)

References 10 publications

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“…To correct for nonidentical phase responses, it is necessary to measure the complex power spectrum on a strong continuum source. Details of calibration procedures in VLBI spectral line observations are given by Moran (1973), Reid et al (1980), Moran and Dhawan (1995), and Reid (1995Reid ( , 1999.…”

Section: Time and Frequency Errorsmentioning

confidence: 99%

Very-Long-Baseline Interferometry

Thompson¹,

Moran²,

Swenson³

2017

Astronomy and Astrophysics Library

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In 1967, a new technique of interferometry was developed in which the receiving elements were separated by such a large distance that it was expedient to operate them independently with no real-time communication link. This was accomplished by recording the data on magnetic tape for later cross-correlation at a central processing station. The technique was called very-long-baseline interferometry (VLBI), a term recalling the earlier long-baseline interferometers at Jodrell Bank Observatory, in which the elements were connected by microwave links that had reached 127 km in length. The principles involved in VLBI are fundamentally the same as those involved in interferometers with connected elements. The tape recorder and its successor, disk storage, can be considered as an IF delay line of limited capacity with an unusually long propagation time, weeks instead of microseconds. The use of tape and disk recording media is motivated entirely by economics and places substantial limitations on the system. Satellite links have been demonstrated (Yen et al. 1977), but their high cost discourages their use.Tape recorders have been entirely replaced by compact disks. Data can also be transmitted to correlation facilities via the Internet in quasi real time. However, latency and throughput are significant issues, and data buffering is usually required.

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Section: Time and Frequency Errorsmentioning

confidence: 99%

Very-Long-Baseline Interferometry

Thompson¹,

Moran²,

Swenson³

2017

Astronomy and Astrophysics Library

View full text Add to dashboard Cite

show abstract

“…The analysis of these quantities have been made by Moran (1973). We will only give the results and remember that the analysis of Moran assumes no ionospheric propagation path effects.…”

Section: Rg(t) Is the Imaginary Part Of The Complex Visibility Functimentioning

confidence: 99%

“…The 2c term is the bias and has to be removed. The signalto-noise ratio for this case is given by (Moran, 1973) T. where N = T/T^, the number of samples to be averaged incoherently.…”

Section: Coherent Averagingmentioning

confidence: 99%

“…(b) Strong signal case; For this case A»(j, the probability distributions of the fringe ang>litude and the fringe phase are given by The signal-to-noise ratio is given by (Moran, 1973)…”

Section: Coherent Averagingmentioning

confidence: 99%

“…For a point source the expected value of the phase is known to be zero (Moran, 1973). But, in the presence of the ionospheric and clock phase noises, the phase of each complex number obtained every 0.2 sec has three conçonents: ionospheric component, clock component and statistical conçonent.…”

Section: A Data Acquisition and Analysismentioning

confidence: 99%

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