I got a warning message that the IGS Precise Orbit was not available at the time of processing, but the "rapid" was used. What does that mean? We will not have the "final" IGS Precise orbit until the International GPS Service (IGS) completes a full week (Sunday through Saturday). This final precise orbit is the combination of seven analysis centers worldwide. It can take these analysis centers several days to upload the orbit to the IGS so the availabilty of a Sunday orbit can be 19 days. The IGS rapid orbit is used in the absence of the IGS precise orbit. However, this is not cause for alarm since the IGS rapid is nearly as "good" as the IGS precise. How does this relate to positions on the ground? Since most OPUS baselines are less than several hundred kilometers, the differences between using the IGR (rapid orbit) and the IGS (precise orbit) is barely detectable if at all. Because of this, OPUS has discontinued this warning message (1/1/2004). For more information see IGS. Some of my attempts to submit data generates a return email saying, "The observations to slip ratio is too low. There were an unusually high number of cycle slips in the data set. Aborting ..." (Code 1012). What does this mean, and how can I correct it? This error message primarily indicates that your carrier phase data set contains too many cycle slips to assure an automated hands-off processing to obtain accurate results. The data may still be useful, but will require human intervention to efficiently resolve the cycle slips. Perhaps nearby radio interference or obstructions have caused an unusual amount of cycle slips. I am trying to upload a RINEX file and I am getting a message that there are illegal characters in the file name -- what am I doing wrong? The problem is probably not with the file name, but with the path name. OPUS is run on a UNIX machine, and it can only read path names that contain numbers, letters, the period, dash, and the underscore. If you move your file to another directory, it should be able to be uploaded. FAQs - Static I uploaded data. Why no response? Solutions are usually sent within a few minutes, but it may take more than an hour to complete if traffic is heavy or your file is large. You will eventually receive either a solution or a failure message. Take care to enter your email address correctly and check your spam filters. My nearest CORS weren't used. Why not? OPUS tries to use your nearest CORS, but tests the integrity of each dataset, and will expand the search area until enough quality data are found. Also note some CORS data are not available until the following day. You may use OPUS options to force include or exclude specific CORS. Is antenna required? If I select "NONE" will it use the L1 phase center? While strongly recommended, if you leave the antenna as NONE your data will be processed with no offsets applied, resulting in a position a few centimeters above or below the L1 phase center. Ignoring your antenna's phase center variations will be interpreted as changes in tropo delays, causing errors in the tropo parameters which will degrade your solution. What is the ARP height for Leica antenna model SR 399, with GRT44 tripod mount? If you have this type of antenna mounting, the ARP height can be determined by using the following equation: Height of ARP (meters) = 0.350 + tape measurement (meters) "Tape Measurement" is the distance in meters from the bottom of the hook in the antenna mounting to the monument. Why do so many antennas include the term "NONE"? What are SPKE, SNOW, SCIS, etc? A NONE suffix means no radome, a shell occasionally used to protect permanent antenna installations. OPUS identifies antenna types using the 20-character antenna+radome codes adopted by the International GNSS Service (IGS); see antenna calibration for more information. My NAD83 coordinates are missing. Why? Sometimes OPUS uses CORS from outside the NGS CORS network that only have IGS reference frame positions and no listed NAD83 positions. Your resulting positions will be just as good as if all CORS were used, except the NAD83 positions will not be listed. You may wish to go to the NGS home page, click on "Products and Services", and download the program HTDP. This program converts positions between different reference frames. How do the NAVD88 heights from GEOID18 compare with heights from GEOID12B, GEOID09, GEOID03, or GEOID99? Newer geoid models provide improved orthometric height accuracy. Upgrade your older GPS heights as follows: NAVD88new geoid = NAVD88old geoid - new geoid ht + old geoid ht. Use the interactive computations tools within geoids or VDatum to compute geoid heights for your project area. contact OPUS Sharing your OPUS solutionWhy share?Your data helps maintain local ties to the National Spatial Reference System (NSRS). Your shared solutions will also help your community prepare for the NSRS modernization in 2022 by contributing to the GPS on Bench Marks for the Transformation Tool campaign (GPS on BM). The Transformation Tool will enable conversions from current vertical datums to the new North American-Pacific Geopotential Datum of 2022 (NAPGD2022). To see examples, check out shared solutions near you.
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