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
The Australian Contributors for Occultation Science T. A. C. O. S. currently Tony Barry, Dave Gault, Dave Herald and Hristo Pavlov
Universal Time from GPS { + } = Universal Time +/- 0. 000001 sec (GPS manufacturer’s specification) Device accuracy = +/- 0. 0001 sec Note to self… 1 pps LED lit on all devices Note display delay
IOTA-VTI International Occultation Timing Association – Video Time Inserter
IOTA-VTI Screens Position Screen Time Screen
IOTA-VTI GPS Almanac Management System (GPS-AMS) C B A 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
IOTA-VTI Data Quality Assurance (DQA) “Live” On Timer Screen n n IOTA-VTI samples the serial data and the 1 pps 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
GPS-ABC Global Positioning System – Atomic Bomb Clock for visual occultation observations
The coded beep of GPS-ABC has a clear and static free coded time-beep n n n every second beginning of the minute 10 th, 20 th, 30 th, 40 th and 50 th seconds 55 th, 56 th. 57 th and 58 th second 59 th second = normal beep = long beep = short beep = brief beep = silent (no beep) Click to hear GPS-ABC and John Vetter in action Or goto You. Tube - http: //www. youtube. com/watch? v=32 NYYs_9 AS 8
GPS-ABC Almanac Management and Position Sentence
Hand Wired GPS-ABC #8 by Chris Chad Cost ~ $115 in parts
Printed Circuit Board GPS-ABC Home Assembly or Ready-to-Go n n 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 n the catch, I need orders for 10 to purchase the PCB – currently @ 2 n contact Dave for more info.
ADVS Astronomical Digital Video System
ADVS features at a glance Astronomical Digital Video System; n is progressive scan video n is all digital n is 12 bit data (Flea 3) and 14 bit data (Grasshopper. Ex) n exposure range 30 frames per second to 8 seconds per frame n has one CCD read noise per frame n frame Central Exposure Time accuracy +/-0. 001 seconds UT n no Instrument Delay compensation required n OSD not overlayed on the image data, does not block FOV n has control of camera gain, gamma and offset n has three modes of screen gamma (linear, lo-gamma & hi-gamma) n uses. adv file format n. adv file can be repaired if not closed properly (i. e. power outage) n video analysed using Tangra 3 n video easily converted to FITS, complete with metadata n supports 3 models of cameras
ADVR screens Keystroke Menu Key = r to record s to stop
ADVR screens Almanac 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
Tangra 3 by Hristo Pavlov
Questions?
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