Lately the precision has been pretty lousy in the afternoons. Switching towers doesn't seem to help and it's been happening in a few different regions. I'm in South Florida and I've wondered if the rover is getting too hot. In the AM when temps are mildly hot things are fine, but very much fickle in the afternoons. It's not because of storms or heavy cloud cover so?ÿI'm curious if?ÿanyone could offer their experiences whether my theory?ÿis totally foolish.?ÿIt's been two to five tenths off from the precision before lunch which sucks. Just curious why this pattern has developed as it seems to be more than a coincidence.
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I noticed here in central Indiana a couple days ago in the afternoon, clear skies, 16 birds, float only, no fix. ?ÿA conundrum.
A couple weeks ago in our hottest weather my display went unreadable after sitting in the sun.?ÿ I rigged shade for it and it recovered.?ÿ That session didn't match the prior one on that disk very well, and I wonder if the receiver was also suffering.
I got to watch a documentary on Florida and it's environment and from what was explained the summer season consists of afternoon thunderstorms as a regular seasonal feature.?ÿ
Of course the afternoon satellite geometry will differ some. If you add in that atmospheric disturbance, I wonder how much that could tip the positional accuracy.?ÿ
I, one time, worked through an approaching cold front and watched the estimated positional solution skyrocket. It did settle down once the atmosphere normalized between the RTN base and rover.
That is the satellite availability for Miami for July 30th with a 15* elevation mask. As you can see even with GLONASS in the afternoon there are some spikes. I chose 15* because most of the time i don't have an open field with perfect view of the sky. I have at least one or two buildings.?ÿ
Best site that i have found for mission planning is here?ÿ http://satpredictor2.deere.com/homePost
@eric-kara?ÿ ?ÿHey, thanks for that tip about the planning site. It looks pretty spiffy.
for us down in NZ where there are more Beidou sats up there than GPS ones at times this one is more useful (bit slower to load though)?ÿ
I've been seeing some of this myself, but the numbers the DC is showing me would indicate it shouldn't be that way.?ÿ Every time I've been out in the past month, around 2:30 or 3 it seems I cannot fix, especially when using VRS.?ÿ I'll have 13-16 sats, good geometry and all, but it will do nothing but stay in float.?ÿ Give it 10-15 minutes to an hour and she's up and running again.?ÿ Very weird...
I've been seeing some of this myself, but the numbers the DC is showing me would indicate it shouldn't be that way.?ÿ Every time I've been out in the past month, around 2:30 or 3 it seems I cannot fix, especially when using VRS.?ÿ I'll have 13-16 sats, good geometry and all, but it will do nothing but stay in float.?ÿ Give it 10-15 minutes to an hour and she's up and running again.?ÿ Very weird...
I wonder if it is something happening on your VRS server.
Do other surveyors in your area report the same issue? You might like to ask around...
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Same thing again yesterday. Wouldn't fix and then poor quality. Still thinking the dish could be getting too hot. I'm in SW FL and we've noticed this trend regardless of the proximity to certain towers although GSchrock's points are potentially part of the issue as well. We have had clear an open skies with plenty of satellites. It just seems odd that RTK work in the earlier part of the day are normal and good. Afternoon goes poorly after about 2PM. I've pulled the dish and put it in the AC a few times and then we're back in business. I'm still not certain heat is the only element. Interesting besides aggravating when you're trying to wrap up a day's work.
Same here w javad gear. Round 2:00 afternoon. Gets poor.
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Same here w javad gear. Round 2:00 afternoon. Gets poor.
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It's the opposite?ÿhere in?ÿNY. I am finding that NYSRTN connects in seconds all day, at any time, and it is giving far better results in recent weeks. I'm using MSM nearest mount to access GPS, GLONASS, GALILEO, L2C and L5. When I perform EDM backsight checks now, I?ÿconsistently see distances less than 0.02'.
NYSDOT has tried twice to update their Leica Spider NET to Network MSM, but they have failed twice. I sure hope when they do get it working, they don't break it. I understand they are trying to enable RTCM3.x MSM5, while my current software?ÿonly uses RTCM 3.x MSM3.
Thunderstorms will screw up sessions.?ÿ I had a job where thunderstorms where moving in south of our project and when I post processed my 2 shots where thousands of feet off where they were supposed to be.?ÿ When the storms moved through everything got back to normal.
We've noticed poorer RTK quality this time of year in the afternoons for several years. In the winter its fine. We've seen this enough to believe it's real. Even short baselines get a little fuzzy at times but most longer such as those you get in network environments quite often.?ÿ I attribute it to what Mr. Schrock cites mostly. You just need to get a feel for when to use it and when to put it away by the way its acting.?ÿ Or use it on less precise features during the afternoon. (if you have any) We need to keep in mind how many concurrent miracles need to happen in the process to get precise RTK results.?ÿ
In late August 2009 I was locating manholes in Boynton Beach.?ÿ I'm as serious as I can be about this.?ÿ I could not get a fix before 9 am and after 3 pm.?ÿ I tried talking to the Leica dealer.?ÿ I tried talking to Scott Harris.?ÿ There was nothing to be done other than pack it up at 3.
I noticed here in central Indiana a couple days ago in the afternoon, clear skies, 16 birds, float only, no fix. ?ÿA conundrum.
Depending on where in the country you are, the FAA regularly schedules GPS jamming events to test systems.?ÿ We were flying a project between Detroit and Toronto, and that was in that same time span.?ÿ We just leave the planes on the ground when they test, because the IMUs wont make no data any better.?ÿ I'll see I can locate the NOTAMS that they work these under.?ÿ It's real, and happens when they want it to.
Solar storms aside, not much effects the GPS signals to lose all functionality, unless it's an intentional process.
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Atmospheric titillation
Updated:
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Here's the NOTAMS for today near my office:
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!GPS 08/139 ZDV NAV GPS (UTTR GPS 18-03) (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A 404NM RADIUS CENTERED AT 401401N1132754W (BVL144032) FL400-UNL, 344NM RADIUS AT FL250, 257NM RADIUS AT 10000FT, 261NM RADIUS AT 4000FT AGL, 181NM RADIUS AT 50FT AGL. 1808141500-1808141700
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link to website to check for GPS jamming:
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https://notams.aim.faa.gov/notamSearch/nsapp.html#/
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Yesterday I got a fix in the woods on a forty corner at about 2:00pm. by 2:30 I'd taken about 6 fixed shots. Only 2 of them were within 0.1' of each other, and they were the last two shots. The separation between them was only about 4 minutes, so I don't have a ton of confidence in them. I keep trying for another hour but the satellite geometry just kept getting worse. I went from 8-10 satellites to 4-6 satellites (including Glonass). I finally gave up. I'll traverse into them tomorrow. I had to tie the creek anyway, I just didn't want to start this far south. This is with a Topcon Hiper+ sitting in?ÿan open field as a base and Topcon GR3 rover. I really think I would?ÿ have done better at a different time of day.
