en.wikipedia.org/wiki/Real-time_kinematic_positioning
2 corrections found
A continuously operating reference station (CORS) is a station that continuously broadcast corrections, usually over an Internet connection.
This misdefines CORS. Official NOAA sources define CORS as permanent GNSS reference stations that continuously collect and distribute observation data; broadcasting real-time corrections is optional, not what makes a station a CORS.
Full reasoning
NOAA’s National Geodetic Survey, which operates the U.S. CORS network, defines CORS in terms of providing GNSS data/observations, not continuously broadcasting real-time corrections.
- The NOAA CORS Network page says the network stations “provide Global Navigation Satellite System (GNSS) data” and that agencies share “GNSS carrier phase and code range measurements” with NGS for analysis and distribution.
- NOAA’s geodesy tutorial likewise says CORS “continually record GPS signals” and that “This data is then distributed over the Internet for download and archived for future use.”
Those descriptions directly contradict the article’s statement that a CORS is a station that continuously broadcasts corrections. Some CORS installations can be configured to support real-time correction services, but that is a possible use/configuration, not the defining meaning of CORS itself.
2 sources
- NOAA CORS Network - National Geodetic Survey
The NOAA Continuously Operating Reference Station (CORS) Network (NCN) ... provide Global Navigation Satellite System (GNSS) data... Each agency shares their GNSS carrier phase and code range measurements and station metadata with NGS, which are analyzed and distributed free of charge.
- CORS and GIS: Global Positioning Tutorial
Working 24 hours a day, seven days a week, CORS continuously receive GPS radio signals... This data is then distributed over the Internet for download and archived for future use... The CORS system is a network of stations ... that continually record GPS signals, and then provide the data to GPS users over the Internet.
PPP uses globally applicable corrections about the satellite's orbit and clock ("state space") and uses a long term of observation to resolve the integer ambiguity
This confuses standard PPP with ambiguity-resolved PPP. In conventional PPP, carrier-phase ambiguities are typically estimated as float values and do not become fixed integers just by observing longer; integer fixing is the purpose of PPP-AR/PPP ambiguity-resolution methods.
Full reasoning
The statement is inaccurate because conventional PPP does not ordinarily resolve integer ambiguities simply by using a long observation time.
Primary-source literature describes standard PPP as an ambiguity-float method:
- A 2016 Sensors paper states: “Conventionally, the IF ambiguities are estimated as float values.” It further explains that in the conventional PPP model, the ionosphere-free ambiguities “cannot be fixed to integer values.”
- A 2020 Sensors paper likewise says that in the traditional PPP model, because of hardware delays, “the combined ambiguity parameter is a float term, loses integer characteristics.”
Longer observation time in PPP helps the float solution converge to high accuracy, but that is not the same as integer ambiguity resolution. Restoring/fixing the ambiguities to integers requires the extra bias/phase-clock information used in PPP-AR (and related PPP-RTK approaches), which is exactly why those methods exist.
2 sources
- Tightly Coupled Integration of GPS Ambiguity Fixed Precise Point Positioning and MEMS-INS through a Troposphere-Constrained Adaptive Kalman Filter
Conventionally, the IF ambiguities are estimated as float values... In the conventional PPP model ... the IF ambiguities cannot be fixed to integer values.
- Research of Eliminating the Day-Boundary Discontinuities in GNSS Carrier Phase Time Transfer through Network Processing
The traditional model ... is a commonly used model for GPS PPP. However, due to the effects of hardware delays in both code-pseudorange and phase measurements, the combined ambiguity parameter is a float term, loses integer characteristics.