Stanford Palmer Visit Robert Moore 14 March, 2001

Transcription

1 Stanford Palmer Visit 2001 Robert Moore 14 March, 2001

2 Contents 1. Tasks 1.1 Maintenance 1.2 Upgrade 1.3 Calibration 1.4 What is Currently at Palmer? 1.5 Packing List 2. Trip Report 2.1 Antenna and Preamp 2.2 VLF Hut 2.3 Narrowband 2.4 Broadband 2.5 Analysis Software 2.6 Retrograde 2.7 Inventory 3. Recommendations 4. VLF Operations Instructions / Notes 5. Appendix

3 1. Tasks 1.1 Maintenance 1. Glacier / Structural (6 days) a) check cables to antenna (open connectors) b) re-drill posts for cable along glacier path c) remove ice beneath wooden base of antenna d) replant guy lines and posts for antenna e) check antenna orientations 2. Sea Ground Check (2 days) 3. Update Markings and Labels in VLF Hut 4. Repair Connections and Mechanics as required 5. Check VLF Sea Ground Isolation from Hut 6. Check Posts to make sure Antenna is not Leaning 1.2 Upgrade 1. Broadband a) Install new broadband code b) Activate Interface2000 Controls as designed by Trabucco and Barrington-Leigh (Computer now controls Cal-Tone Injection) c) Check for multi-day stability d) Check that the first snapshot is not missed e) Check that the system is Idle when not acquiring f) Send Working Version to Maria for South Pole 2. HAIL N/S and E/W a) Install new HAIL Software b) Check for connectivity with Stanford

4 c) VLF Receivers to Track: Call Location f(khz) Lat. E. Lon. Computer NLK Jim Creek, Washington NS/EW RHA Rhauderfehn, Germany EW NPM Lualualei, Hawaii EW NAU Puerto Rico NS/EW GBR Great Britain EW NST La Moure, North Dakota NS/EW NAA Cutler, Maine NS NWC NW Cape, Australia NS RPS Eastern Siberia, Russia NS 3. Continuous Recordings -- 2 days worth 1.3 Calibration 1. antenna and receiver (2 days) 2. Measure antenna position / dimensions 3. Ampex Dismantling 1.4 What is Currently at Palmer? khz Pentium II's, and a 200 khz Pentium III 2. Programmer Clock (Stanford) 3. AMPEX System 1.5 Packing List 1. Software CD with BB Software and New HAIL Software 2. Matlab 3. Visual C Digital Camera

5 2. Trip Report From March 24 th to April 8 th, 2001, Robert Moore (Stanford University) conducted a site visit for A0-106-P. Minor hardware upgrades and significant software upgrades were undertaken in the VLF/Clean Air Hut. After a successful one-year overlap, the AMPEX system was removed from the site, leaving the digital Broadband system to take its place. Nearly half of the old rack equipment was removed for retrograde. Of the three computers in the hut, two are continuing to survey narrowband VLF transmitters in order to record ionospheric modifications due primarily to lightning electron precipitation from the inner radiation belts. Upgraded software for these two computers allow us to record narrowband phase data much more accurately than before. The third computer, after successfully duplicating the reel-to-reel AMPEX recorder for one year, continues to acquire full-spectrum broadband data for 1 minute of every 15. In addition, the VLF antenna on the glacier was re-aligned to the geographic axis, and routine maintenance was conducted on the antenna and the feed-line running between the hut and the antenna. The antenna is now ready for winter. 2.1 Antenna and Preamp 1. Aligned antennae to geographic N/S and E/W as was done the previous year. The coordinates of the antennae corners, relative to S64 46' 28.3", W64 3' 1.8", are as follows (all measurements in meters): Corner North East Altitude Sigma North South East West Center After chopping out the 1-year-old ice platform and re-solidifying the base of the antenna tower, we considered using a fiber-grate platform to replace the wooden base of the tower (the fiber-grate allows the ice beneath it to melt). Of course, the ice under the fiber-grate would melt faster than the surrounding ice, if we did not keep the grate covered with a piece of ply-wood. However, the Science Technician could melt the ice collecting at the base of the antenna periodically by removing the ply-wood top. 3. Directly upon my arrival at Palmer, knot winds caused the guy rope anchoring the antennae wires to snap. After clearing out the ice-base and redrilling the antenna posts to the aforementioned configuration, we re-hoisted the tops antennae triangles to 10 meters. The height is now marked on the antenna tower.

6 4. The feedline posts were down when I arrived. We re-drilled the holes for the posts and suspended the feedline. 5. The Preamp post was leaning on the antenna tower. We re-planted this post to its upright position. The Preamp itself is in good order. There was no corrosion or need for other repair. 2.2 VLF Hut 1. Dismantled the AMPEX and the Programmer Clock (Stanford). 2. Moved the Betamax Systems into the rack space cleared by the AMPEX (See Appendix for before/after pictures). 3. Enabled Interface2000, giving control of the Calibration tone to the Broadband Computer (tone previously controlled by the Programmer Clock). 4. Re-wired and re-organized the octopus of cables in the rack (See Appendix for picture). 5. Executed VLF calibration for the preamp/line receiver (See Appendix for Calibration Tables and Plots). 6. VLF ground in Hero Inlet inspected (good condition), but not scrubbed. 7. VLF Hut ground is successfully shielded from Station ground. 8. Made additional shelving for the racks and applied minor fixes to the rack setup so that overheating from the instruments cannot occur. 2.3 Narrowband 1. Combined the Palmer-specific Narrowband software with our more generic Narrowband Data Acquisition software in use in the United States and Canada. This upgrade gives us the ability to track any Narrowband transmitter inputted by the user. It also tracks MSK-modulated signals with higher accuracy than before, providing better phase data with significantly less noise than previous versions. This new Narrowband software also offers the capability of acquiring continuous Broadband data while tracking six Narrowband transmitters. 2. Implemented a real-time connection with Stanford (when the Communications Satellites allow). This connection enables Stanford to change the Narrowband timing settings remotely. 3. Implemented six-channel acquisition in each of two Narrowband computers: North/South: NLK, NAA, NWC, NAU, NST, RPS East/West: NLK, RHA, NPM, NAU, GBR, NST

7 2.4 Broadband 1. Installed a new Broadband Acquisition Software package. This package allows the user to input acquisition timing down to the second (previous version allowed for only the minute). This upgrade saves significant amounts of memory when we are interested in acquiring data during specific satellite passes. 2. Filenames are different from the previous version: the start second of the acquisition is included. 2.5 Analysis Software 1. Narrowband Analysis Software no longer works with the new filename convention. 2. Broadband Analysis Software continues to work with the new Broadband filename convention. 2.6 Retrograde Sent North the following items: - 1 AMPEX Reel-to-Reel Unit - 1 AMPEX Power Panel - 4 AMPEX Filter Panels - 1 Programmer Clock (Stanford built) - 1 Oscillator - 1 Hardware Unit (Clock-specific Hardware -- Stanford built) 2.7 Inventory (Incomplete) - Tektronix 455 Oscilloscope, handles broken - Tektronix 475 Oscilloscope - Large Brown Toolbox - Four Racks of components (well-stocked) - Box of Assorted Cables - Variety of ICs - Calibration Box (Gray) - Weller soldering iron - Heat gun - BNC connectors for RG-58 cables - Breadboard - CD Burner Spare

8 3. Recommendations 1. Fiber-grate replacement for the Antenna Tower base, with a removable plywood top. 2. Need extra Monitor/Keyboard/Mouse extensions in order to clean up the 3- computers-to-1-monitor-keyboard-and-mouse system. 3. Need more RAM for the 2 Narrowband computers. I recommend 128 MB each. 4. Need more Banana cables and Audio/Video to BNC coverters. 5. Bring 2 DVMs with you to make the calibration process easier. Others can be found on station, but not necessarily at the time you need them. 6. Bring Software manuals. 4. VLF Operations Instructions / Notes Daily Operation Execute matlab on each of the narrowband (NB) machines. The recent night's data should display automatically. Check the amplitude data for coherence, and if there are interesting features, use the menu option to make a graphics (jpeg) imprint of the data. If 650 MB of data have accumulated, write them to CD. The CD label should include the words "Matlab format" and "Joliet," the latter signifying that long filenames exist and can only be read under Windows. Write the broadband (BB) data to CD. The data amount to nearly 3.5 CD's per day. Data from more than one day can be put on a CD. The CD labels should include the words "Matlab format" and "ISO09660." Once per week, examine a spectrogram for coherence by choosing to view a BB file from the VLFtool. To add the menu to a broadband figure, just type "VLFmenu" at the matlab prompt. CD Writing Blow gently on the active side of a blank CD, as well as on the CD tray, to remove any dust before use. The Broadband machine is capable of writing CD's at "6x" speed simultaneously with its data acquisition operations, since it is doing no real-time digital signal processing. Glacier Work The high-pressure point of a pick axe works best when trying to clear out the ice-column beneath the antenna tower. Troubleshooting If any of the three data acquisition systems seems to not work correctly, first power cycle the computer. Often software glitches are fixed by a simple reboot.

9 5. Appendix Palmer Frequency Response Using Ev Paschal's equation for a balanced receiver, the following 2 Digital Conversion Factors were calculated: A Broadband Digital Sample of X corresponds to a free-space electric field intensity of Y mv/m. A Narrowband Digital Sample of X corresponds to a free-space electric field intensity of Y mv/m.

10 VLF Hut Racks Before: After: VLF Storage:

11 Example of Organized Cables: A View of Palmer from the VLF Antenna: