****************************************************************************** BSW Electronic Mail 08-Dec-2009 16:09:01 CET Message Number 0289 ****************************************************************************** Author: Mark Greaves Subject: Optimal settings for SIGMA ambiguity resolution strategy Dear Colleagues, I am currently processing a regional network with stations in UK and Ireland plus European stations from Iceland to central Spain. My average baseline length is around 70 - 100 km and all stations have good quality, 24 hour, dual frequency data so I am using the QIF ambiguity resolution strategy. However, my network has the potential to have some VERY short baselines of just a few meters. There are also two baselines at ~20 km. I have currently "swapped" the very short lines for ones ~50 km long, by using the DEFINED setting in SNGDIF, and processed all lines with QIF. For comparison I would like to test the effect of solving the ambiguities on the short lines with the SIGMA strategy instead. I have never used SIGMA before and would like to know if anyone has some advice on the optimal settings to use especially regarding the ionosphere. My current settings are to introduce the global ionosphere model from CODE (CODwwwwd.ION) and to process L1&L2 frequencies together. My SIGMA specific settings in panel GPSEST 3.2.2 are: Maximal No ambiguities per iteration =3D 10 Ambiguity resolvable if 1 integer within =3D 3.0 Maximal sigma of resolvable ambiguity =3D 0.07 Minimal sigma used for testing =3D 0.05 I have not set up Stochastic Ionosphere Parameters. Does any one have ideas for better settings? Thank you in advance for any replies. Best regards Mark Mark Greaves MSc MRICS Geodetic Analyst, Ordnance Survey c/o C505, Romsey Road, SOUTHAMPTON, United Kingdom, SO16 4GU Phone: +44 (0) 77 7183 3355 www.ordnancesurvey.co.uk | mark.greaves@ordnancesurvey.co.uk=20 Please consider your environmental responsibility before printing this email =20 This email is only intended for the person to whom it is addressed and ma= y contain confidential information. If you have received this email in er= ror, please notify the sender and delete this email which must not be cop= ied, distributed or disclosed to any other person. Unless stated otherwise, the contents of this email are personal to the w= riter and do not represent the official view of Ordnance Survey. Nor can = any contract be formed on Ordnance Survey's behalf via email. We reserve = the right to monitor emails and attachments without prior notice. Thank you for your cooperation. Ordnance Survey Romsey Road Southampton SO16 4GU Tel: 08456 050505 http://www.ordnancesurvey.co.uk =0D [Mailed from: "Mark Greaves" ]