NOTES FROM C. CARILLI and G. WATTS in FALL of 1998. MOST OF THESE REQUESTS WERE IMPLEMENTED IN MAJOR STIFR UPGRADE IN MARCH, 1999 ---------------------------------------------------------------- December 22, 1998 from: C. Carilli, P. Dooley, G. Watts to: J. Ulvestad re: Site Testing Interferometer cc: R. Sramek, M. Goss, F. Owen, J. Wrobel, C. Janes, L. Beno, R. Perley, G van Moorsel, T. Cornwell The site testing interferometer (STIfR) has been operational for about two years at the VLA site. The system is being used by outside observers for real-time decision making when observing at high frequency at the VLA using software and documentation on the VLA home page. It can also be used to obtain statistics on the quality of the VLA site for high frequency observing, both diurnally and seasonally. The original installation of the STIfR was for testing purposes only, hence the electronics are housed in a temporary wooden shack built by G. Petencin. Dynamic scheduling is being considered at the VLA. The site testing interferometer could play an important role in dynamic scheduling of the VLA. However, we believe that long term operation of the STIfR requires significant alterations to the current temporary installation, and more dedicated support from Socorro operations. The current temporary installation has been fraught with hardware, communications, and software problems. Our goal is to have reliable operation of the STIfR by the next A array (summer 1999). This may require a temporary shut-down of STIfR operation to fix hardware and communications problems. The main problems currently are: 1. Hardware and Infrastructure: The main problem with the installation is the temporary wooden shack. This could be alleviated using a container of the type used for the interference monitor. Such a container is available at the site. See note below from Watts concerning other hardware modifications. DONE MARCH 1999 2. Communications: The current communications link is via the Y-com and two PCs, then to miranda. A fiber has been laid to the shack which should allow direct access of the STIfR PC. The data should probably be logged onto a machine other than miranda, or a disk for STIfR data should be added to miranda. DONE MARCH 1999 3. AOC software support: The current web software is being maintained (nominally) by Tom Folkers in Tucson. This is not acceptable. We need software support from within the AOC. The web interface to the STIfR data could be used as an example for other systems supplying ancillary data relevant to VLA observations, such as TEC from the GPS, or the software could be altered to work within the context of other NRAO software efforts, such as AIPS++ or the new on-line system upgrade. DONE MARCH 1999 !!! 4. STIfR Technical Support staff: The current operation is ad hoc and part time for a number of individuals, all of whom work on the various problems of the STIfR in whatever spare time they can find. Ultimate reliable operation of the STIfR will require a dedicated AOC staff member who is involved with the set-up and operation of the hardware and the software, and who has some knowledge of the use of the STIfR data products, such as is being done with the RFI monitoring program, and is presumably being planned for the GPS receiver at the VLA site. Operation of the STIfR would not be a full-time job, but perhaps could be incorporated into a `package' involving operation of other facilities at the VLA site which provide ancillary data relevant to VLA observing. The re-installation of the hardware in the next few months may be a good time to initiate such support. PARTIALLY DONE MARCH 1999. Chris Carilli, P. Dooley, and G. Watts ------------------------------------------------------------------ -------------------------------------------------------------------- -------------------------------------------------------------------- FOLLOWING IS NOTE FROM G. Watts, 18 November 1998 THESE FIXES WERE IMPLEMENTED IN MARCH 1999 -------------------------------------------- VLA Site Testing Interferometer, Needs as of 18 November 1998 Galen Watts and Chris Carilli The interferometer was originally installed for a six month test period. It has now been in use for about two years and the desire to make it a permanent VLA fixture has been expressed. On 17 November we visited both antennae and the shack and see the following improvements to be necessary for a permanent installation: Antennae: 1. The feed cover needs to be secured with hardware, it is currently secured with electrical tape. 2. Cabling along feed support arms needs to be secured with more ties and possibly all cabling moved to bottom support arm. 3. The junction box on back side of dish needs a weather-proof cover or some other kind of protection for the connectors. 4. The heliax and DC wiring needs to be secured so it doesn't touch the concrete pad or the ground. 5. The DC wiring needs to be spliced securely and weather tight. 6. The pipe carrying cabling from the shack needs to have an inverted 'U' installed where the pipe exits the ground to prevent water from entering the conduit and some kind of screening installed inside the openings to keep animals out of the underground conduit. The Computer Shack: 1. The shack needs to be replaced with an instrument shelter similar to the one used in the RFI installation (which would help in reducing RFI caused by the interferometer). There is an instrument shelter at the site currently not being used, it was formerly used for the receiver range and Paul Lilie has said it would be acceptable to commit the unused instrument shelter to the interferometer. 2. The electronics enclosure needs to have the RF section thermally insulated and the computer installed in the enclosure (to help reduce RFI). 3. Wiring inside the shack needs to be dressed neatly and labeled as to function and destination. 4. Phone-in reboot needs to be installed for the PC 5. Phone-iin interrupt needs to be installed for the STIfR (in case of loss of phase lock). ---------------------------------------------------------------- Issue 1: Other hardware problems: -------------------------- Problem Possible Solutions ------- ------------------ Amplitude Changes Could be a beacon problem? Change scaling on plots. Wrong Beacon/Confused Beacon Need to check beacon with scope every few months LO lock Installed Heaters Break lock if necessary by disconnecting IF cable (need automatic switch via software) HVACed shack Rodents Improve infrastructure Lightening Install new PC board plus serge protectors Wind moving antennas Re-point (not a problem thus far) -------------------------------------------------------------- Issue 2: Software and Communications ------------------------------- Problem Possible Solutions ------- ------------------ Socorro Support Need someone in Socorro to oversee software. Software interrupt Need to be able to reboot PC and interrupt STIfR via phone-in. Full Disk on Miranda Compress every 3 months Back-up every 6 months NEED TO ADD DISK TO MIRANDA More diagnostics from STIfR eg. phase lock indicator history window the history window goes off-screen statistics call-up statistics over specified time range Wind help file Point out in help files conditions when reference pointing would fail Get `properties window' immediately hard to find otherwise Not getting weather station data restart web software Time sequence some 10 minute records look short, (FIXED by TF 1/99) such that the plot has `spikes' Time sequence The structure function and data (FIXED by TF 1/99) displayed occasionally get out of synch Lose Weather Station Data Restart analysis software or (FIXED by TF 1/99) reboot miranda X-windows The current system uses NETSCAPE for (done TF) the help files, and X-windows for the data display. This leads to problems with color usage on the local machine, and precludes use of the system by users without X-windows. Can we move system to NETSCAPE alone? Time sequence MST did not get up-dated with the (done by TF) sequential plots such that the white line is out of synch with data Two numbers give user two numbers right-off (done) for ease of use (eg. rms and cycle time) Unnecessary Plots A few of the plots are principally for (done) debugging (the phase histogram and the phase time series) Crowded Plots Plots with three values (temp/dew (done) point/pressure and time series of rms phase, wind speed, PL slope) Help Files There should be a simple `how-to' (done) example, pointing out the critical plots, numbers, and equations. ---------------------------------------------------------------- Operations Problems The current method of determining the operational status of the STIfR is semi-regular spot checking by Chris Carilli, with subsequent phone calls to Phil Dooley and G. Watts if there are problems. Clearly such an ad hoc scheme is not acceptable for long term operation of the STIfR. We hope that the STIfR could be managed as part of standard operations at the VLA. This would entail regular checking of the data by the operators, or other personal, with problems reported in an appropriate way. Carilli had an instructional session with the operators in April 1999 on how to operated the Web interface to the STIfR. D. van Horn has generated a standard MAINT form. However, standard checking of the STIfR by the operators has yet to be instigated. ---------------------------------------------------------------