Delivered-To: igsstation@igscb.jpl.nasa.gov Message-ID: <5ACEEE96F4F9D41190790002A528B51E0709782B@S0-OTT-X11.NRCan.gc.ca> From: =?iso-8859-1?Q?=22Ferland=2C_R=E9mi=22?= To: "'igsstation@igscb.jpl.nasa.gov'" Subject: [IGSSTATION-476]: Change to discontinuity table format Date: Mon, 16 May 2005 11:31:18 -0400 Content-Type: text/plain; charset="iso-8859-1" Sender: owner-igsstation Precedence: bulk ****************************************************************************** IGS Station Mail 16 May 08:31:28 PDT 2005 Message Number 476 ****************************************************************************** Author: R. Ferland Dear IGS Colleagues, As you most likely know, files summarizing station coordinates time series discontinuities are being used to keep track of events affecting coordinates time series. To improve the usefulness of such file, it was recently suggested within IGS to also include the type of modeling as well as the axis that may be affected by the discontinuity. The proposed changes were first suggested during an IGS meeting at the EGU, and then circulated within the IGS Reference Frame Working Group and to IERS. The proposed changes could eventually also be used to document the models used in a combined file (assuming that SINEX is also expanded). In the recently accepted discontinuity format, which is intended to keep track of station coordinates time series discontinuities. The discontinuity block includes for each station (code + pt + soln) a validity interval. ex: +SOLUTION/DISCONTINUITY *CODE PT SOLN T _DATA_START_ __DATA_END__ _______________COMMENTS_______________ ALBH A 1 P 00:000:00000 94:104:00000 Antenna Change ALBH A 2 P 94:104:00000 95:011:80100 Antenna & Receiver Change ALBH A 3 P 95:011:80100 00:000:00000 ...................... -SOLUTION/DISCONTINUITY For proper modeling of time series coordinates, it may be required to have more than coordinate discontinuity. Velocity discontinuity, as well as other models discontinuity may be needed along one two or all 3 axis. To address those, it was proposed, within IGS, to extend the format to include modeling refinements as well as 1D 2D or 3D application of the model. This can be achieve by adding one column to specify which model is used/activated/reset and another column specifying which axis the model is being applied to. Commonly used models for time series analysis are: - Position / Velocity (P , V) - Periodic signal, namely Annual (A) and semi-annual (S) - Exponential decay (E) etc... M=models (P,V,E,A,S,...) More models can potentially be added without a need to updated/change the format again. In the current procedures, only P&V are used. By also adding one axis column, one could refine the use/reset of a Model to a given axis, local and geocentric coordinates are proposed (E,N,U) or (X,Y,Z) (similar to eccentricity). The character "-" could mean all axis (3D). e.g.: A=Axis (X,Y,Z,E,N,U,-) An example for the updated discontinuity table including models and Axis may look like: +SOLUTION/DISCONTINUITY *CODE PT SOLN T _DATA_START_ __DATA_END__ M A _______________COMMENTS___________ ALBH A 1 P 00:000:00000 94:104:00000 P - Antenna Change ALBH A 2 P 94:104:00000 95:011:80100 P U Antenna & Receiver Change ALBH A 3 P 95:011:80100 00:000:00000 P - ALBH A 1 P 00:000:00000 00:000:00000 V - ALBH A 1 P 00:000:00000 00:000:00000 A - ALBH A 1 P 00:000:00000 00:000:00000 S - ........................... -SOLUTION/DISCONTINUITY The existing format can be easily extended by implying that if no velocity (V) model interval is given, that a constant velocity is assumed. Best Regards, Remi,