The S2 very long baseline interferometry tape recorder

Wietfeldt, R.; Baer, Doug; Cannon, W. H.; Feil, G.; Jakovina, R.; Leone, Peter F.; Newby, P.; Tan, Henry

doi:10.1109/19.543987

Cited by 14 publications

(10 citation statements)

References 11 publications

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“…PKS 2153À69 was observed with three elements of the Australian Long Baseline Array (LBA) on 2003 February 15: the 22 m Mopra Telescope, three of the six 22 m antennas of the Australia Telescope Compact Array (ATCA) tied together as a phased array, and the 64 m Parkes Telescope. The observation was conducted over a 6 hr period, and the data were recorded using the S2 system (Wietfeldt et al 1996), consisting of dual polarization 16 MHz bands centered at 1400 MHz. Each 16 MHz band was 2 bit sampled, giving an aggregate recorded data rate of 128 Mbps.…”

Section: Radiomentioning

confidence: 99%

The Halo, Hot Spots, and Jet/Cloud Interaction of PKS 2153−69

Young

Wilson

Tingay

et al. 2005

ApJ

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We report Chandra X-Ray Observatory and 1.4 GHz Australian Long Baseline Array (LBA) observations of the radio galaxy PKS 2153À69 and its environment. The Chandra image reveals a roughly spherical halo of hot gas extending out to 30 kpc around PKS 2153À69. Two depressions in the surface brightness of the X-ray halo correspond to the large-scale radio lobes, and interpreting these as cavities inflated with radio plasma, we infer a jet power of 4 ; 10 42 ergs s À1. Both radio lobes contain hot spots that are detected by Chandra. In addition, the southern hot spot is detected in the 1.4 GHz LBA observation, providing the highest linear resolution image of a radio lobe hot spot to date. The northern hot spot was not detected in the LBA observation. The radio to X-ray spectra of the hot spots are consistent with a simple power-law emission model. The nucleus has an X-ray spectrum typical of a type 1 active galactic nucleus, and the LBA observation shows a one-sided nuclear jet on 0B1 scales. Approximately 10 00 northeast of the nucleus, X-ray emission is associated with an extranuclear cloud. The X-ray emission from the cloud can be divided into two regions, an unresolved western component associated with a knot of radio emission (in a low-resolution map), and a spatially extended eastern component aligned with the parsecscale jet and associated with highly ionized optical line-emitting clouds. The X-ray spectrum of the eastern component is very soft (À > 4:0 for a power-law model, or kT ' 0:22 keV for a thermal plasma). The LBA observation did not detect compact radio emission from the extranuclear cloud. We discuss both jet precession and jet deflection models to account for the progressively increasing position angle from the northern hot spot to the western component of the jet/cloud interaction region to the direction of the parsec-scale jet. In the precession model the particle beam impacts the western region, while the radiation beamed from the nucleus photoionizes the eastern region and is scattered into our line of sight by dust, giving rise to the polarized optical emission and possibly the soft X-ray emission. If the X-ray emission from the eastern region really is dust-scattered nuclear radiation, it would be the first detection of such emission from an external galaxy. The nearby galaxy MRC 2153À699 is also detected by Chandra.

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Section: Radiomentioning

confidence: 99%

The Halo, Hot Spots, and Jet/Cloud Interaction of PKS 2153−69

Young

Wilson

Tingay

et al. 2005

ApJ

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“…al 1967), the Mark II system (Clark 1973), the Mark III system (Rogers et. al 1983), the Mark IV system (Whitney 1993), and the S2 system (Wietfeldt et. al 1996), or to hard disk systems such as the Mark 5 system (Whitney 2002) and the K5 system (Kondo et.…”

Section: Introductionmentioning

confidence: 99%

A New Hardware Correlator in Korea: Performance Evaluation Using KVN Observations

Lee¹,

Oh²,

Roh³

et al. 2015

Journal of The Korean Astronomical Society

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Abstract:We report results of the performance evaluation of a new hardware correlator in Korea, the Daejeon correlator, developed by the Korea Astronomy and Space Science Institute (KASI) and the National Astronomical Observatory of Japan (NAOJ). We conduct Very Long Baseline Interferometry (VLBI) observations at 22 GHz with the Korean VLBI Network (KVN) in Korea and the VLBI Exploration of Radio Astrometry (VERA) in Japan, and correlated the aquired data with the Daejeon correlator. For evaluating the performance of the new hardware correlator, we compare the correlation outputs from the Daejeon correlator for KVN observations with those from a software correlator, the Distributed FX (DiFX). We investigate the correlated flux densities and brightness distributions of extragalactic compact radio sources. The comparison of the two correlator outputs shows that they are consistent with each other within < 8%, which is comparable with the amplitude calibration uncertainties of KVN observations at 22 GHz. We also find that the 8% difference in flux density is caused mainly by (a) the difference in the way of fringe phase tracking between the DiFX software correlator and the Daejeon hardware correlator, and (b) an unusual pattern (a double-layer pattern) of the amplitude correlation output from the Daejeon correlator. The visibility amplitude loss by the double-layer pattern is as small as 3%. We conclude that the new hardware correlator produces reasonable correlation outputs for continuum observations, which are consistent with the outputs from the DiFX software correlator.

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“…The MkIII is now being replaced with a much higher performance MkIV system and the VLBA has seen performance increases since its initial design. Recently, a new low-cost S2 recording system (Wietfeldt et al 1996) and correlation system have been developed in Canada for the purpose of supporting Space VLBI and geodetic VLBI (Cannon et al 1997). The S2 correlator, described herein, can also be upgraded with recorders up to four times the bandwidth of the S2 recorders.…”

Section: Introductionmentioning

confidence: 99%

The S2 VLBI Correlator: A Correlator for Space VLBI and Geodetic Signal Processing

Carlson¹,

Dewdney²,

Burgess³

et al. 1999

PUBL ASTRON SOC PAC

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A unique lag-based VLBI correlator system has been developed for the purpose of supporting both S2-based Space VLBI observations in the Japanese-led VSOP mission and the Canadian Geodetic VLBI program. The system architecture has been designed so that replication of a small number of modules can be used to construct systems with a wide range of sizes. Optimized for a large correlator, the design is 'station-based' in the sense that as many hardware and software functions as possible are performed before data is replicated and transmitted for baseline (station pair) processing. As well as delay compensation and generation of phase rotation coefficients, station-based functions include autocorrelation, tone extraction, pulsar gating, signal-statistics accumulation, and digital filtering. Doppler shift correction (fringe stopping) is performed on a baseline basis at each correlator lag so that there are no smearing effects (lag-dependent loss of coherence) or frequency shifts that must otherwise be corrected after correlation. This is a key element that simplifies the baseline processing architecture when high accelerations associated with an orbiting antenna must be considered. Flexible, efficient distribution of data from station-based hardware to baseline-based hardware is accomplished by serializing the wide data paths to 1 Gbit/s signals and using high-speed switches to route the signals to their final destinations where they are de-serialized before cross-correlation. This greatly reduces the size, wiring complexity, and cost of the system. The interval between updates of the delay models, integration times, and other important events is typically 10 ms, but can be as short as 1 ms. Within this period, delay and fringe model generation is performed using linear hardware synthesizers. The correlator also contains a number of unique signal processing functions that extend its capability beyond a basic VLBI correlator: flexible Local Oscillator frequency switching for bandwidth synthesis; rapid (1 ms) correlator dump intervals (allowing, for example, the study of some single-pulse pulsar characteristics on VLBI baselines); simple but powerful multi-rate digital signal-processing techniques to allow correlation of signals at different but related sample rates; and a digital 'zoom' filter for producing very high resolution cross-power spectra. The correlator software, written almost entirely in 'C', is highly integrated into the system, supports all of the functions mentioned above, and is re-configurable to support expansion of the correlator. The software schedules the use of hardware resources to enable correlation of multiple observations concurrently, and automatically schedules the correlation of observations that require more than the available number of physical playback terminals. There is also substantial pre-correlation consistency checking. The delay model is based on CALC for ground-based antennas and NAIF for space-based antennas. Output data is stored in the UVFITS format. The paper describes the des...

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The S2 very long baseline interferometry tape recorder

Cited by 14 publications

References 11 publications

The Halo, Hot Spots, and Jet/Cloud Interaction of PKS 2153−69

The Halo, Hot Spots, and Jet/Cloud Interaction of PKS 2153−69

A New Hardware Correlator in Korea: Performance Evaluation Using KVN Observations

The S2 VLBI Correlator: A Correlator for Space VLBI and Geodetic Signal Processing

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