VLBA Correlator Interfaces for VSOP-2 Jon Romney NRAO, Socorro VSOP-2 Tracking Meeting Madrid / Yebes 2007/2/19 -20 1
Essential Initial Digressions The NSF Senior Review Panel convened by NSF Division of Astronomical Sciences. Report released 2006/11/3. Primary goal: “redistributing roughly $30 M 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. ” 2007/2/19 -20 – jdr VSOP-2 Tracking Meeting Madrid/Yebes 2
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 $6 M annual operational cost, at rate corresponding to ~$2 k/hour. Relevant options for VSOP-2: NASA and/or ISAS. May require reducing scheduled observing time. Upgrade VLBA’s sensitivity to expand range of science it can address. 2007/2/19 -20 – jdr VSOP-2 Tracking Meeting Madrid/Yebes 3
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. 2007/2/19 -20 – jdr VSOP-2 Tracking Meeting Madrid/Yebes 4
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 5 A, 5 B, or (hopefully) more advanced wideband system. Prompt delivery requirements same (probably even more stringent) VSOP-2 Tracking Meeting i. e. , “Bologna as for VSOP -2007/2/19 -20 – jdr Rules”. Madrid/Yebes 5
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. 2007/2/19 -20 – jdr VSOP-2 Tracking Meeting Madrid/Yebes 6
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). 2007/2/19 -20 – jdr VSOP-2 Tracking Meeting Madrid/Yebes 7
Thank you 2007/2/19 -20 – jdr VSOP-2 Tracking Meeting Madrid/Yebes 8
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