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VLBA Correlator Interfaces for VSOP-2. Jon Romney NRAO, Socorro VSOP-2 Tracking Meeting Madrid / Yebes 2007/2/19-20. Essential Initial Digressions. The NSF Senior Review Panel convened by NSF Division of Astronomical Sciences. Report released 2006/11/3.
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VLBA Correlator Interfacesfor VSOP-2 Jon Romney NRAO, Socorro VSOP-2 Tracking Meeting Madrid / Yebes 2007/2/19-20
Essential Initial Digressions • The NSF Senior Review • Panel convened by NSF Division of Astronomical Sciences. • Report released 2006/11/3. • Primary goal: “redistributing roughly $30M of annual spending” from existing facilities, to invest in new facilities. • Primary recommendation on VLBA: “to seek assistance in operating the VLBA for a finite time from the international user community and, perhaps, also from NASA and the Japanese [ISAS] where there is a strong synergy with its missions.” VSOP-2 Tracking Meeting Madrid/Yebes
The NSF Senior Review • NRAO Responses to SR Report • Concentrate on delivering high-profile science,in areas consistent with NSF Astronomy’s mission. • Seek non-NSF support for ~33% of $6M annual operational cost, at rate corresponding to ~$2k/hour. • Relevant options for VSOP-2: NASA and/or ISAS. • May require reducing scheduled observing time. • Upgrade VLBA’s sensitivityto expand range of science it can address. VSOP-2 Tracking Meeting Madrid/Yebes
The VLBA Sensitivity Upgrade • 22-GHz Receivers • Replacement of LNAs. • 4-Gbps Data Path • Replacement of all equipment downstream from IFs. • New wideband Sampler/Filter module. • Compatible with VSOP-2 channelization. • New wideband Recording system. • Disk-based; compatible with existing Mark 5 module pool. • New Correlator. • WIDAR- or software-based. • Planned upgrades to existing playback interface abandoned. VSOP-2 Tracking Meeting Madrid/Yebes
VLBA Correlator Interfaces • Discussed Here in Context of New Correlator • Existing correlator incompatible with VSOP-2 channelization; limited to 256 Mbps (for > 10 stations) without PBI upgrade. • Observation Data (Input) • 1- (2-,4-) Gbps data rate OK; subject to media pool constraints. • Recorded on Mark-5-standard disk modules. • Format TBD: Mark 5A, 5B, or (hopefully) more advanced wideband system. • Prompt delivery requirements same (probably even more stringent) as for VSOP -- i.e., “Bologna Rules”. VSOP-2 Tracking Meeting Madrid/Yebes
VLBA Correlator Interfaces(Continued) • Orbit Data • Generally, same requirements as for VSOP. • Accuracy specifications TBD, possibly depending on correlator. • Format preferably same as JPL orbit kernels used for VSOP; could be changed for a different OD organization. • Logs • New correlator an opportunity to move to new log format. • Hope to develop new global standard. • Prompt delivery requirements same as for VSOP. VSOP-2 Tracking Meeting Madrid/Yebes
VLBA Correlator Interfaces(Continued) • Time Correction Files • Presumably also required for VSOP-2. • No known reason to change VSOP format. • GPS Offset Files • Recommend merging into new Log format. • Visibility Output Data • TBD, as appropriate for post-correlation analysis system(s). VSOP-2 Tracking Meeting Madrid/Yebes
Thank you VSOP-2 Tracking Meeting Madrid/Yebes