@field-dog I'm unfamiliar with what the baseline length is. Please explain.
?ÿ
Baseline length = distance between base and rover = "vector length".
?ÿ
RTK and NRTK specs have a distance-dependent error just like total stations do, such as "8mm + 2ppm".
With a long enough baseline/vector, that PPM value will contribute enough error to push a position out of tolerance (depending on what your project tolerance is).
This is why there can be such a variation in RTN "quality" - some are dense enough to give users a reliable solution whether they select single-base or network solution, others are not.
Still others (like here in WA) are variable - denser and excellent in certain areas (western part of state) and spread out and so-so in others (eastern part of state).
Again this is why it is hard to say a particular RTN is "bad" or "good". Like surveying in general, it all depends...
I can't see why such a spec could be anything but an average over good conditions, a rule of thumb. There is nothing in GNSS that explains ppm dependence except propagation variations that is highly variable from day to day, and you don't know if today is typical.
This is unlike EDM where the frequency standard design may have a typical ppm range of drift.
@bill93?ÿ ?ÿWe need a ppm for the ppm. Or a plus or minus for the plus or minus. Nowadays I am getting Network RTK at about 0.035mm +/-0.025mm +/-3200ppm
So If I understand this correctly, if your in an area with more NRTK bases or are close to a base then the ppm will be lower and produce less error, so will resemble a traditional base and rover setup with regard to residuals? Also, if your in an area that has few and far between NRTK bases then you stand to typically see higher residuals than a traditional base and rover setup?
Didn??t Jerry Reed have a song about PPM or was that ???? PXx i guess. Lol. Sorry I just had it pop in to my head. Maybe some of the old timers have heard it but I am sure some have never even heard of Jerry Reed.
The issue here is that all crews MUST use same control and it must be a requirement to do so.
?ÿ
?ÿ
The issue here is that all crews MUST use same control and it must be a requirement to do so.
Ehhhhh...
?ÿ
Whose control?
What datum?
Which epoch date?
Which RTN?
What mountpoint?
Single-base or network solution?
(Or are we going base-rover and ditching the RTN?)
How many epochs to observe?
Which constellations to use?
Which geoid?
Which equipment?
(Do we just run with conventional gear, no GNSS?)
Post-processed & adjusted, or not?
How many redundant observations before we are satisfied?
What's our tolerance for check shots?
(What's the network accuracy of that control?)
?ÿ
?ÿ
Sorry for the stream-of-consciousness, but in my experience there's more to control work than "use these points, it's a requirement".
From the post it sounded to me as though they were all using different control that each crew created....this simply does not work and will create big headaches. Of course they should all be on same datum, localization if any, etc.
?ÿ
