Gea and Gemini are monitoring systems based on GNSS receivers.
They are designed to monitor large structures (bridges, dams, high-rise buildings) as well as landslides and subsidences.
Our GNSS monitoring systems are based on a combination of M-rovers that are placed in
the zone to be monitored, R-rovers that are placed outside the monitored zone and
used as reference points, and a PC running the software. The PC can also be a remote
server.
Rovers are based on dedicated hardware; a GNSS receiver plus power supply and
communication. The PC running our software gathers data from the deployed
rovers.
GEA rover differs from GEMINI in terms of performance and cost.
GEA is suited for low phenomena such as landslides or subsidence and can reach a
precision of 1 mm over 7 days of continuous monitoring.
GEMINI is suited for higher-rate monitoring (up to 50 Hz) and therefore is best
suited to structural monitoring. Its precision can go below 1 mm over 7
days of continuous monitoring.
GEA and GEMINI improves the precision of GNSS system, but how do they work?
The principle is to correct the GNNS error sources, that are:
Ionospheric Delay: The Ionospheric layer contains ions particles
which delay the satellites signals and affect the position accuracy. The Ionospheric
delay varies
with solar activity, time of year, season, time of the day and location. Ionospheric
models are used to reduce ionospheric delay errors.
Tropospheric Delay: Variations in tropospheric delay are caused by
the changes to the humidity levels, temperature and atmospheric pressure in the
troposphere.
Tropospheric models are used to estimate the amount of error caused by tropospheric
delay.
Multipath: It occurs when a GNSS signal is reflected off an object,
such as the wall of a building, to the GNSS antenna. Because the reflected signal
travels farther to
reach the antenna, the reflected signal arrives at the receiver slightly delayed.
This delayed signal can cause the receiver to incorrect calculate the position.
Orbit Errors GNSS satellites travel in very precise, well known
orbits. However, the orbits do vary a small amount. Also, like the satellite clocks,
a small variation in
the orbit results in a significant error in the calculated position.
Receiver Noise It refers to the position error caused by the GNSS
receiver hardware and software.
GEMINI |
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Update rate Up to 50 Hz |
GNSS signal single or Dual L1/L2 |
Accuracy Sub-Millimetric |
Baseline < 100 Km |
NTRIP Protocol Supported |
Global Reference Station Protocol Supported |
Communication by High speed LAN |
GEA |
---|
Update rate Up to 5 Hz |
GNSS signal single frequency L1 |
Accuracy Millimetric |
Baseline < 5 Km |
Communication by LoRa Mesh |
Low-priced Solution |
Gea and Gemini work based on the data analysis coming from two or more baselines
created by GNSS receivers. A base station is identified and located outside the
monitoring zone, one or more monitoring stations are installed on the structure in
question. Stations communicate with each other through radio or wired connections. A
PC Server collects all the data from the stations and analyzes the baselines.
Software can send email or SMS alarms based on previous defined trigger events.
This is a standard question and since we are using a GNSS receiver with 5 m precision
(in the worst case), how is it possible to achieve 1 mm precision?
Precision is increased on the server side with specific algorithms which work on the
mitigation of the following source of errors:
You can have GNSS-MONITORING configured according your needs