Post Processing Methods

Ppk can be hit and miss. I wouldn't rely on it to post process 100%, I will set base for it o?ÿ days I'm doing miles of cadastal, just in case I'm in a radio dark spot and find a corner. In 15 years, I've only used it once for topo. I was in a secure area on a usaf installation and base battery died late in the day.

Static is my preferred method for setting many control points at once. Rarely practical for anything else.

Is there really no way to have control over ppk, and have a way of knowing if youre getting a fixed or float solution before going to the office?

For occasions where i'm getting float solutions, how long should i perform a static for 2-5km baselines to get the fixed result? Will 30 mins be enough to get to all these tough spots

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I don't see these issues with PPK. Be sure you have open sky, PPK isn't for canopy. 3 minutes to fix, refix if you lose lock. Keep fixed as long as possible after the session. Ive turned down the fix time to 60 seconds to test how far it could be pushed and have no issues with the R8. Also check your settings for processing, there could be a time setting that is blocking the processing. Take a few minutes and run tests in the parking lot, 2-5km is basically right next to the base, 30 minutes is not necessary for static that close. PPK, fast static, static, its all the same thing. Running an hour long PPK session will process as well as an hour long static session, the difference is that you can collect many points during the hour.?ÿ

I can collect a point in PPK for 15 minutes and there is no difference in the file compared with 15 minutes of static collection.

Many surveyors in the states have been trained to collect everything for OPUS and think 4 hours of collection is a minimun, the old guys were trained with the rule of thumb of 10 minutes plus 1 minute per mile. And that is for high accuracy points in a network with redundancy. And that was with old recievers that have been replaced with new gear, ?ÿmuch more accurate and way more efficient.?ÿ

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To the user there is little between static and rapid static. The only difference being the length of the baselines and the observation times.

I've used PPK and Stop and Go in classroom environments. Never for production.?ÿ ?ÿ

If using Trimble, You can run an RTK survey with the base collecting, for any loss of Radio during the survey.?ÿ Select RTK and Infill, and make sure you're recording and storing the base data.?ÿ You'll have to post process all the static shots, and the base will be your static base to use for this. We did it ( still do) across huge areas when we lose the RTK radio to no slow down the production value of bodies int he field.?ÿ The Post Processing though, is the bane of the field ops manager for sure.......Good times!

RTK Infill is a nice feature, Xfill is even better, it gives you a bit of time to collect points when you lose radio.

Infill is ok, it is basically a PPK session with a fix taken before you lose radio, it's best that you know you are going to lose radio however. What Infill will do is make sure with RTK that your fix is good. Which may be the way you want to go since you are having issues. But understand, once you enter Infill you are doing a PPK session with the same issues you have if you do one outside of infill.

The best help an experienced surveyor can give you is to tell you to get more education. A proper survey education will explain the differences and more precisely the differences you get under different conditions. Now it appears you want to know what is best, well there is no best but there are betters for each different condition you encounter. That may come with education, but mostly requires more experience.

I would say PPK is best tried after you have mastered all the other formats. Personally I see it's greatest value in reconnaissance, where even a poor solution can still give you valuable information.

I finished an 8 point GPS network on Saturday and one OPUS-RS solution failed to fit into the network. Even the PP vector was long. Both close points had the best possible sky. I am holding the L1 only point and using the?ÿL1/L2 point for azimuth and do not plan to reobserve. I will hold the field traverse distance between the 2. Sometimes it may not be worth it to attempt perfection.

Paul in PA

The best advice I can give you would mirror what Paul already stated. There is no cooky-cutter recipe and every situation is a little different. Depending on the terrain, obstructions, distance from the base, all of these are going to affect the length of observation times or even if I'll make an attempt at all. Frequently if it's a critical point I will make a point to observe it more than once under a different satellite configuration. Planning plays a role if it's going to be a challenging environment. I'll plot the times of the day when the constellation is going to give poor PDOP and avoid those times and focus on the best windows. If the point I need to observe is up against a wall or building or in a dense stand of trees I'll set a few points out in the open and break out the total station to make the tie. It's like anything else. Knowledge and experience coupled with good planning and a clear understanding of the limitations of your equipment?ÿare all?ÿrequired to obtain consistently good results. PPK is just another tool in the box.

All the methods require adequate time to fix the integers, static and rapid static is the same thing, just short and long static occupations, obviously rapid static is going to be better on shorter lines.

All kinematic is pretty much the same, stop and go just picks up discrete points whereas continuous kinematic (I guess sometimes called PPK) is the same, just recording points such as topo from a moving platform like an ATV for instance.

ALL require a minimum time to fix the ambiguities to the satellites with parameters you monitor such as number of length of line, satellites, DOP's, etc. Once fixed, then you need to maintain lock and acceptable numbers of satellites, DOP's, etc.

If the fixed ambiguities disappear, you start over, each "chain" is independent.

Best teacher of this is experience and doing it, I pretty well know if it will likely be a good solution in the field, BUT you don't get the real time feedback you do with the real time methods, which are really the same as post processed just being carried out in the field with a real time data link.

I have done tons of all methods in the last 25+ years, and often do as much PPK as anything else as that is part of the "control" for aerial mapping sensors along with IMU's, ground control and the aerial triangulation process.

SHG