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Table of Contents

VTC Members are encouraged to contribute short project status reports on this page.

New VGOS stations and station upgrades to VGOS

GGAO

GGAO and Westford resumed their VGOS Demonstration Series sessions in November and have observed three more sessions of 1, 5, and 24 hours.

Arthur Niell - 2016 Jan 27

Kokee

       The observations for the commissioning phase of the 12m has been completed, ending with three 24 hour observing sessions between K2, Wf, and Gs.  The data are being correlated and analyzed.  We are working toward the VLBI Operation Readiness Review (ORR) now scheduled for August, which means release of final documentation, software and procedures.

Chet Ruszczyk - 25 May 2016

       Verification and checkout of 12m is under way.

  1. Trained the KPGO staff on using the 12m signal chain first week of February
  2. On Feb. 5th successfully obtained fringes on source 1749+096 with GGAO 12m and Westford Broadband system
  3. On Feb 12th executed a mixed mode observation, between the 12m and the Kk 20 S/X antenna and successfully obtained
    fringes.
  4. We are presently exercising the integrated system (Field system control of antenna and backend subsystems).
    1. This shakedown period is leading to identifying shortcomings in operational manuals and procedures, along
      with potential bugs before the acceptance review.
  5. Full summary of the ongoings at KPGO can be found here: http://space-geodesy.nasa.gov/blogs/KPGO/index.html

                                                                                                                                                                                                                                                                                                                                                       Chet Ruszczyk - 24 Feb. 2016

Wettzell

  1. The Eleven feed is installed and tests are ongoing. 
    1. The amplifiers are kept at 17.00 K continously and the feed itself has a temperature of about 10 K.  The feed works well and I have done the first G/T measurements with good results. The G/T values are very similar to that of the Triband-feed, which in turn are really good. I tried to measure the Tsys with a small broadband antenna, but my noise diodes have not enough power to calibrate the system. I need to find a more efficient way. I will continue with the measurements as soon as the weather is good enough. 
    2. A problem arises, since the feed is really ultra-broadband. It works down to 500 MHz and it is able to receive GPS, GSM und terrestrical TV-transmitters as well. Therefore we probably need a high-pass filter to avoid the saturation of the postamp and the receiver.
  2. Christian and Alex have working to setup DBBCs and the Fila10G to connect it to the Mark6 systems and it is now operational, first feedback tomorrow from correlator Bonn; investigations on controlling Mark6 from Field System is ongoing They have solved a few problems, but it is still a lot of work to do there.

Gerhard Kronschnabl and Alexander Neidhardt - 24 Feb 2016

Ishioka

  1. Operation of Ishioka antenna is now under interruption because of construction of operation building, and will resume after April. 
  2. Modification of cryogenic dewar for QRFH system is being done. 


Yoshihiro Fukizaki - 28 Jan 2016

Onsala

– the first two containers from MTM with electronic equipment etc. are expected to arrive tomorrow, May 27
– six containers with reflector panels of the first telescope, etc. are expected to arrive around June 1st
– the az- and el-cabin of the first telescope are expected to arrive around June 8
– the assembling work will start immediately after that
– the containers for the second telescope are expected to arrive 1-2 weeks later
– the receiver design and development work for both telescopes is ongoing
– the 11-feed for system-1 is on site
– we are waiting on the CalTech QRFH for system-2
– the DBBC3s for both systems are ordered and expected to be delivered in October

Rüdiger Haas - 26 May 2016

Construction sites webcams.

Shanghai

The antenna is ready but there are some delays with the approval of the foundations. The foundations will be installed no earlier than October so construction will not start before then. The Shanghai VGOS antenna will be ready for its first test observations around the middle of 2017

Guangli Wang - 28 April 2016

Construction of the antenna foundation and tower to be completed by June, with observations starting before the end of this year.

VGOS system will be 16 Gbps, cover 2.7 to 15.5 GHz with 1 GHz bandwidths.

Guangli Wang - 13 Feb 2016

AuScope (Hobart, Katherine and Yarragadee)

Initial testing of Stirling Cycle broadband system has been completed at Hobart. Upgrade of all three sites to broadband planned to be completed by mid 2017 (was hoped to be by the end of 2016).

The prototype is now back in Hobart and will be installed on the 12m in about a week.

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

Boradband (5.9GHz,7.1Ghz,8.7GHz,10.6GHz) VLBI experiments on GALA-V network (Kas34-MBL1-MBL2) were repeated several times(May26, Jun24, Jul10). It s purpose is evaluation of broadband VLBI precision. Observed data were correlated by GICO3 software correlator and stored in Mk3DB. Then solution with CALC11/Solve indicating that even with small diameter antenna (SEFD~5.e5Jy vs SEFD~2000 Jy pairs), we can get geodetic solution with ~30 ps delay residual.  It is promising that VGOS (2000Jy - 2000Jy) observation should get high delay precision measurement. We are planning to make further test experiments with Ishioka-MBL1-MBL2 in August. A long baseline observation test was made between Yebes-Kashima34 in June. but because of observation modes were different at each site (Broad channel at Kashima and narrow channel at Yebes), correlation process is required some modification. Another test experiment has been discussed between Takefuji and Jim.

 

Mamoru Sekido - 27 July 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.

The antenna phase cal unit has a temperature control system which has been switched off to avoid subbands in the phase cal tones.

UDCs are installed and working.UDCs 2 and 3 connected to one DBBC2

One Mark6 was installed and configured. 4 packs 32 TB each are inserted and work as a single group. There are two optical connections between the DBBC2 and the Mark6. 

One RDBE-G installed and configured. The RDBE-G is also connected to the Mark6.

The second DBBC2 is used for observations with the 40m RT. usage for VGOS requires that no VLBI osbervations happen simultaneously between the 13.2m and the 40m. A DBBC3 will be ordered very soon and 3 or 4 RDBE-Gs may also be ordered soon.

Pablo de Vicente - 25 May 2016

The 13.2m antenna stopped operations (VS observations with the S/X/Ka receiver) on January 8th and is under upgrade works: the backstructure is being covered with cladding and fans are being installed in between the backstructure and the cladding. The three band receiver cryostat is going to be updated with a new head, and a new compressor compatible with the broad boand receiver is beeing installed. All these works are expected to complete in February 18th.

The new broadband receiver with a quadrige horn was mounted in the lab during the third week of January and it will be tested during the next weeks. Preliminary receiver temperature measurements have been performed. The best results (with a balanced amplifier) show receiver temperatures below 25 K between 5.5 and 15 GHz.

4 UDCs have been built and are mostly finished. We have been waiting for the delivey of some filters for some weeks and it is foreseen they will arrive but the end of februrary. Once they are completed they will undergo tests and be installed together with the optical modules in the backends room.

One Mark6 has been received and will be installed during the first week of february. 12 diskpacks 32 TB each have been purchased.

Pablo de Vicente - 28 Jan 2016

S/X Observations with fast antenna network

Two FAST observations were performed in December 2015.

  • The first observation coded FAST02 was a 24 hour run starting on December 16th. Four stations took part: Badary (Bv), Yebes (Yj), Wetzell (Wn) and Zelenchuskaya (Zv). Scans were tipically 20 seconds long. DBBC backends at Wn and Yj used DDC mode: 14 channels, 16 MHz each channel. recording rate was 2 Gbps. Frequency setup is the same as R1. Only one polarization. No correlation has been performed yet. 
  • The second observation coded FAST03 was a 6 hour starting on December 20th. Four stations took part: Badary (Bv), Yebes (Yj), Wetzell (Wn) and Zelenchuskaya (Zv). Scans were tipically 20 seconds long. PFB mode was used in this case: 7 contiguous 32 MHz channels in S band and 7 contiguous 32 MHz channels in X band, only one polarization. Recorded rate was 2 Gbps. No correlation yet.

Pablo de Vicente - 28 Jan 2016

Results from FAST02:

    • Fringes to all stations found at S and X bands: Wn, Yj, Bv and Zv. LO difference of 0.99 MHz between Wn, Yj and Bv, Zv were solved at correlation.
    • Correlation was done at Bonn and at Kvazar.
    • Fringe plots Wn-Yj & Wn-Bv attached.
    • SNR plots show that scans 20 seconds long yield a good SNR. An integration time of 10 seconds should still yield results with a good SNR. Plot from Bonn attached.

Pablo de Vicente - 24 Feb 2016

GGAO, Westford, Wetzell, Yebes Broadband Fringe Testing


The preliminary VGOS observing sessions between GGAO (Gs) , Westford (Wf) , Wetzell South (Ws) and Yebes (Yj) has resulted in fringes between all sites for three sessions.  Schedules were generated for theses sessions.  The configuration of the systems for the tests have been as follows:
  1. FT6119 
    1. Gs and Wf have been recording all four bands using UDCs, RDBE-Gs and Mark6.
    2. Ws and Yj recorded band B (sky frequency of 4712.4 GHz) with the DBBC2 and Mark6.
      1. The PCFS (version 9.12.13 ) was used to control the systems.
    3. Fringes were detected for both polarization for Ws but only 1 for Yj (configuration error was the cause for not both polarization's).

  2. FT6128 was a retest of FT6119 with the goal of correcting configuration issues and other anomalies observed.
    1. Fringes were detected for both polarization for Ws and Yj.  
    2. Anomalies still existed.

  3. FT6140 incorporated BandC ( 5832.4 GHz)into the observation for Ws and Yj (2 Band Test)FT6XXX Next steps under discussion.
    1. Fringes were detected for both bands / pols.
    2. Improved performance to earlier tests
    3. Investigations continues.
    4. Yj, RDBE-G was tagged along on Band B.  No fringes detected, problem determined.

Chet Ruszczyk, for folks at Gs, Wf, Ws, Yj, Haystack and Ed (PCFS) - 25 May 2016


Technology Updates

DBBC3

The development activity is mainly concentrated on the realization of the unified control software which connects all the functionalities realised by the different parts of the system.

A number of calibrations are required for each IF and simplification/automatization methods are under test. A number of commands will be added to the control software in order to activate in background such 'continuous' calibrations if required.

The firmware available at present is the DSC full band with bw up to 4 GHz for each IF. PFB with 256 MHz channels is in development, so as DDC with 128-64-32-16-8.
A combination of the three modes will be implemented.

A number of VGOS complete systems (8 IFs) is under  construction.

G. Tuccari - 26 Jan 2016

DBBC3 Report    

The DBBC unified control software was completed in the main tasks, still remaining to be added the functionality for the DDC and PFB modes,
now possible with low level commands. Completion in its first formal version and testing are under way.

Calibration functionalities are now automated and show to perform well. The entire process is realised in background. The overall speed of the control operations
will be increased.

The complete firmware available at present is the DSC full band with bw up to 4 GHz for each IF.
Activity on the firmware development was concentrated on the DDC implementation so to optimize the functionality and the number of independent bbc elements.

The GPS synchronization was added for the entire set of 8 CORE3H with a single receiver.

The new synthesizer board GCAT has been developed and is in testing phase. It allows to use additional input reference frequencies from the H-Maser (ex. 100MHz)
when this is required.

 

G. Tuccari - 27 April 2016

      DBBC3 Report

The DBBC3 unified control software DUCS is under test and additional functionalities have benn added for
the VGOS 8 IFs version.
In particular the infrastructure for managing the different bandwidth has been improved.
A picture of the DBBC3-VGOS system is attached; its data rate for VGOS 2 bit modes is 128 Gbps, while
the maximum data rate with the same hardware is 512 Gbps.

Additionally it started the realization of the firmware and software to accomplish the standard
DBBC2 functionalities in DDC and PFB mode. This is in particular accomplished by the possibility to
have GCoMo and CoMo modules in a same system.

   DBBC3 - VGOS (full)                                                                                      

 G. Tuccari - 26 May 2016

 

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