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Universal Time by IOTA-VTI GPS-ABC ADVS

Universal Time by IOTA-VTI GPS-ABC ADVS. Dave Gault on behalf of T.A.C.O.S Presented to Trans-Tasman Symposium on Occultations No.8 2014 Friday, 18 th April 2014 Melbourne, Australia.

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Universal Time by IOTA-VTI GPS-ABC ADVS

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  1. Universal TimebyIOTA-VTIGPS-ABCADVS Dave Gault on behalf of T.A.C.O.S Presented to Trans-Tasman Symposium on Occultations No.8 2014 Friday, 18th April 2014 Melbourne, Australia

  2. The Australian Contributors for Occultation ScienceT.A.C.O.S.currentlyTony Barry, Dave Gault, Dave Herald and Hristo Pavlov

  3. Universal Time from GPS { } + = Universal Time +/- 0.000001 sec (GPS manufacturer’s specification) Device accuracy = +/- 0.0001 sec Note to self… 1pps LED lit on all devices Note display delay

  4. IOTA-VTIInternational Occultation Timing Association – Video Time Inserter

  5. IOTA-VTI Screens Position Screen Time Screen

  6. IOTA-VTIGPS Almanac Management System (GPS-AMS) C B A = alert if IOTA-VTI house keeping is incomplete and is unsure of the quality the current almanac. B = time of the last Almanac Update C = Correction to apply to previous timings if an Almanac update occurred A

  7. IOTA-VTI Data Quality Assurance (DQA)“Live” On Timer Screen • IOTA-VTI samples the serial data and the 1pps from the GPS every second • 5 tests every second + 1 test sequentially over an hour • Overall policy is to ‘squawk’ loudly on error • Reports on status of satellite fix

  8. GPS-ABCGlobal Positioning System – Atomic Bomb Clock for visual occultation observations

  9. The coded beep of GPS-ABC • every second = normal beep • beginning of the minute = long beep • 10th, 20th, 30th, 40th and 50th seconds = short beep • 55th, 56th. 57th and 58th second = brief beep • 59th second = silent (no beep) GPS-ABC has a clear and static free coded time-beep Click to hear GPS-ABC and John Vetter in action Or goto YouTube - http://www.youtube.com/watch?v=32NYYs_9AS8

  10. GPS-ABCAlmanac Management and Position Sentence

  11. Hand Wired GPS-ABC #8by Chris Chad Cost ~ $115 in parts

  12. Printed Circuit Board GPS-ABCHome Assembly or Ready-to-Go • Option a; Home Assembly - owner purchases the three major components and a KIT-of-Parts - about an afternoon of work with basic tools and a soldering iron… ……… Cost about $199 • Option b; Purchased Fully Assembled, Tested, and Ready-to-Go …………….. Price $249 • the catch, I need orders for 10 to purchase the PCB – currently @ 2 • contact Dave for more info.

  13. ADVSAstronomical Digital Video System

  14. ADVS features at a glance Astronomical Digital Video System; is progressive scan video is all digital is 12bit data (Flea3) and 14bit data (GrasshopperEx) exposure range 30 frames per second to 8 seconds per frame has one CCD read noise per frame frame Central Exposure Time accuracy +/-0.001 seconds UT no Instrument Delay compensation required OSD not overlayed on the image data, does not block FOV has control of camera gain, gamma and offset has three modes of screen gamma (linear, lo-gamma & hi-gamma) uses .adv file format .adv file can be repaired if not closed properly (i.e. power outage) video analysed using Tangra3 video easily converted to FITS, complete with metadata supports 3 models of cameras

  15. ADVR screens Key = r to record s to stop Keystroke Menu

  16. ADVR screensAlmanac ready or not • GPS Almanac Uncertain • Red question mark • Yellow time display means time is uncertain • GPS Almanac now current • No red question mark • Green time display means:- time is now certain • -1 means yellow times were incorrect:- subtract 1 second

  17. Tangra 3by Hristo Pavlov

  18. Questions?

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