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New VGOS stations and station upgrades to VGOS
GGAO
"Failure and repair of the GGAO broadband cryogenics receiver" (PDF) from Ganesh Rajagopalan and Chris Eckert 22 Aug 2016
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GGAO and Westford resumed their VGOS Demonstration Series sessions in November and have observed three more sessions of 1, 5, and 24 hours.
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Yoshihiro Fukizaki - 28 Jan 2016
Onsala
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AuScope (Hobart, Katherine and Yarragadee)
Nothing new to report since AugustReport on Callisto feed tests on Hobart 12m will be sent to the VTC soon.
Jim Lovell - 22 Sep 1 Dec 2016
Testing of the prototype Callisto feed was completed on the Hobart 12m in August, finishing with a successful fringe test with Ishioka and Kashima. A report on the Australia-Japan broadband fringe tests is available. The receiver operated reliably and stably throughout, installation and operating procedures went smoothly. We are continuing to work on optimising the antenna optics. Still on track for a January arrival of the production systems.
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Tests of Dynamic Scheduling with the three AuScope antennas and others (most recently Hart 26m) are continuing with the next observations planned for June.
Jim Lovell - 26 May 2016
Kashima 34m
- 34m antenna ACU trouble was fixed. There are no significant change and progress at 34m station.
- Broadband 24h experiment was conducted between MBL1-MBL2-Ishioka13 stations. Purpose was to check improvement of residual and precision in geodetic observation. Since precision of delay observables have been exceeding the post fit residuals in Kas34-MBL1-MBL2 observations and it has been indicating troposphere is the limiting factor of geodetic/frequency transfer VLBI. I expected improvement by fast switching with Ishioka-MBL1-MBL2 network. Though the network is small and elevation angles are almost the same for all stations, thus it seems that independence of parameter estimation of Atm is not good enough, unfortunately. Experiment was in 12-13 Sep. and correlation processing has finished. We will try to see the analysis next week.
Mamoru Sekido - 22 Sep. 2016
Yebes
Broadband system temperatures are ~ 50 K - 70 K. The warm amplifiers after the cryogenic ones and before the optical fiber converters had to be removed to avoid saturating the amplifiers used to modulate the optical laser. This increased the Tsys by a factor 2. Furthermore one of the optical channels uses an 18 dB amplifier and the other one 9 dB. This is an issue to be solved in the future.
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We are undertaking a series of Dynamic Observing test observations with the AuScope array and any other antennas that wish to join. Observations are done is S/X mode, 16 x 16 MHz IFs with 2-bit sampling (1 Gbps). The main aims are to test real-time scheduling and observing techniques and make data comparisons between traditional observing modes and dynamic observing output. Data are being eTransferred to and correlated in Vienna. Schedules are updated on a 15-min cycle and telescopes maintain control over participation. For more information, see the Dynamic Observing page on the AuScope VLBI wiki.
Observing program and status for 2016:
| Experiment | Start (at 0 UT) | Duration (h) | Antennas | Comments | ||
|---|---|---|---|---|---|---|
| ds239 | Aug 27 | 48 | HbKeYg | Successful uninterrupted 72h on all antennas | ||
| ds258 | Sep 14 | 24 | HbKeYg | Scheduler adapted well to antenna drop-outs | ||
| ds275 | Oct 1 | 48 | HbKeYgHtHbKeYg | Hart15 to join | ||
| ds288 | Oct 15 | 48 | HbKeYg+ | |||
| Oct 26 | 24 | HbKeYg+ | Not done - too much data to process from previous observations | |||
| ds317 | Nov 12 | 48 | HbKeYg+ | HbKeYgHt | Observed - script bugs revealed | |
| Dec 3 | 48 | HbKeYg+ | ||||
| Dec 16 | 72 | HbKeYg+ |
Jim Lovell - 22 Sep 1 Dec 2016
Technology Updates
DBBC3
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G. Tuccari
on behalf of the development team.
30/11/2016
Firmware development continues and the 3DSC, full band
at 4GHz, evolved at beta version, it is under test and
for now can support in a single CORE3H:
8 independent U&L bbc with 32-26-8-4-2MHz bwd (then 64 bbc and
128 channels in a full VGOS system).
Three useful elements have been added to the project:
a) multicast transmission of ancillary system data
b) delay calibration base unit for a dual/variable frequency antenna unit
c) real time RFI monitoring data logger for all the IFs in their
entire 4GHz band.
Integration of these new elements are still to be integrated into the
DUCS control software.
27/07/2016
A new calibration scheme has been implemented which allow to perform in automatic almost all the settings. The initial characterisation remains to be performed in laboratory and coded in the control software together with a ID in the ADB3L boards. The initial settings for such boards then requires a novel strategy to optimally operate.
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