I collected static data for the second time and again did not obtain a solution from any of the 4 control points when uploaded to OPUS rapid static. I am using an R7 with a zephyr 2 gnss antenna. The area I am collected is a somewhat clear area within a deciduous (no leaves) wooded area. At least 10 satellites were tracked the entire time for all of the collection sessions. I am pondering three things: 1. Should I try to collect for a longer period - maybe even 2 hours or more and upload to OPUS static processing? 2. Should I be using a zephyr 2 geodetic gnss antenna? 3. Is there software out there that will enable me to "weed out" bad collection epochs? I have tried collection at 1, 5, 10 and 15 second invervals for over 30 minutes each control point. Any input would be greatly appreciated! thank you. All points come back with 1 of 2 of the below error messages from OPUS:
FILE: 38391184.DAT OP1493672152668 6034 ATTENTION!! The quality of the GPS data from the rover or nearby 6034 CORS sites was too noisy and below minimum standards to attain a 6034 meaningful solution. To avoid this unexpected inconvenience the 6034 user may want to re-observe at a different hour of the day and for 6034 a longer period of time.
FILE: 38391182.DAT OP1493672185171 6009 The OPUS-RS solution for the position of the rover has 6009 failed to converge after 5 iterations. This could be due to 6009 especially noisy data (among other reasons). If you really need 6009 a position for this station, you might try another data set.
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This information at the NGS site is pretty good.
https://www.ngs.noaa.gov/OPUS/about.jsp
Lots of other good advice on here so far too.
Keith
attached are the files. thank you.
Dear Trout,
I looked at your files and I believe the gravest deficit is a lack of data.
You've collected for about the minimum time requires foe OPUS Fast Static and there were some dropouts inticating probably blocage of signal by trees or the like.
I checked the location of Jeff4 that seems to be on a bridge. I can't tell if it is low because of going down a valley to crosss the stre=am but a look at the photo shows lots of trees, as well as relief. I think it looks a little better than Jeff1 & Jeff2, at least for tree cover.
The ideal time for collecting a static session is 4 1/2 hours. The bare minimum, under good conditions, is about 8 minutes. OPUS works better the more data it has to work with. NGS were of the opinion that requiring a long occupation to use OPUS would hurt its acceptence and popularity.
OPUS Static is more forgiving of ones location, as the geometry of the CORS used is not a concern. The extra time removes that constraint. It uses 3 CORS. The data may be resubmitted with a filter to not use the previous CORS and get a redundant solution with 3 others.
OPUS Fast Static works a different way and is dependent upon the geometry of the available CORS. They should iealy surround your position. Distace from your position is also a factor. It uses several CORS with (I believe) a minimum of 5 required.
The five nearest CORS to Jeff4 are:
1 PAMS 12.13 km
2 NJWC 37.93 km
3 NJSC 46.55 km
4 LUMT 55.31 km
5 WIL1 63.86 km
I don't know anything about them. If any were down durng your session OPUS has to reach out further.
Bottom line, gather at least a few minutes more than 2 hours data, more is better and submit to OPUS Static. You can always chop up the data and see if OPUS Fast Static works. Considering the time that has already been invested, I'd put a good mark on the bridge and take a 4-5 hour session for OPUS Static.
This will give you a known pont not far from the office (home?) from which you can do static or maybe RTK from it or a point you set from it.
Best wishes,
JAC
Mr. Allen's procedure is correct. A minimum of an hour will prevent failure. In doing static gps surveying, Mission Planning is paramont in a successful mission.
One must remember that depending upon the obstructions at each site the total group of stations only see the number of satellites minus all obstructions at all sites at all times in the mission. So while you indicate a receiver saw 10 sats the whole time maybe another site only saw 5 sats for 5 minutes, three sats for 6 minutes and 8 sats the rest of the time. This means that the group only has five common sats to work with for the 5 minute time frame.
I have not had any luck with rapid static. Set your mask to 30 degrees and try a 4-5 hr session.
Going old school here. So a mission plan. Take a compass and clinometer to map out any obstructions. Do a full 360 around your setup. Get any and all objects above 15 degrees and within 100 feet. Since you are in a wooded area you WILL get a lot of time noise from the tree trunks. Do at least a 1 hour session set at a 15 second interval. From your mission plan, pick your time slots so your PDOP is below 3 for the hour. Trimble BC should let you weed your obs file down. I used to trim 5 minutes off the start and end of the file. One last thing, store the data in the R7 and not in the Data collector. Believe it or not I had a crew years ago doing plus and storing it in the Data collector. They started the session and then went to get coffee - taking the data collector with them. Blue tooth works to about 30 feet not 3 miles.... Storing the data in the receiver will be better for you. Hope this helps
Try DPOS
http://geo.javad.com/dpos/
To me it sounds like you will need a longer observation time to obtain the required epochs to get a better solution... Other factors may be how far away the closest CORS Stations are and their relative geometry to where your observations are.
Our office uses Trimble Business Center Complete which allows us to view and edit the satellite information. Good luck with your project!
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