Geodetics RTD Software
Reference Station Networks using
Geodetics' RTD Software
April 2004
www.geodetics.com
About Geodetics
Geodetics, Inc. is a software company based in La
Jolla, California. It specializes in high-precision,
real-time position and navigation solutions based on
its proprietary Epoch-by-Epoch™ technology.
Geodetics and Thales Navigation have partnered to
offer a network RTK solution.
RTD Family of Products
RTD-Pro: Continuous monitoring of static/dynamic dual-frequency GPS receivers
operating in a network including server/client connectivity enabling Epoch-by-Epoch™
RTK.
RTD-Net : Solution for continuous monitoring of permanent GPS networks operating
dual-frequency receivers. Excludes server/client connectivity.
RTD-L1: For short-baseline deformation monitoring applications.
RTD-Data: Receiver control and data storage functionality without network processing.
RTD-Postprocess: Fully automated GPS post-processing software.
RTD-Vector: Fully automated GPS based attitude determination software system
RTD-Clients: Epoch-by-Epoch™ processing for client side.
Geodetics’ Applications
Fleet Tracking
Structure Monitoring
RTK Surveying
Precise Navigation
Deformation Monitoring
Marine
Single Baseline RTK
10-20 km radius
Single RTK Rover
Single RTK Base
Issues with Single Baseline RTK
Overhead: Must own, setup and survey base station
Availability: Single point of failure
Reliability: No redundancy (i.e. multiple determination)
Accuracy: Limited range (10-20 km) and baseline dependent
Initialization/Re-initialization: Seconds to minutes
Security: Must attend temporary base station
Productivity/Efficiency: Low (see all of the above)
Flexibility: Mixing of receivers/antennas problematic
Solution: Network RTK with
Geodetics RTD software
Fully automated GPS sensor network software
for multiple static and dynamic platforms

RTD is a fully automated client-server application designed for realtime, high-precision GPS sensor tracking applications. RTD uses
Geodetics proprietary Epoch-by-Epoch™ algorithms that provide
instantaneous integer-cycle phase ambiguity resolution.

The RTD server centrally controls a network of GPS base stations
through a full suite of data communication, processing, and archiving
functions. Data are made available to multiple clients through the
Internet for real-time positioning with centimeter-level accuracies.
Common RTD User Interface
Network Integrity Monitoring
RTD
Platform Independent
On-The-Fly
Adjustments for
Static/Dynamic
Reference Stations
RTD Server/Client Architecture
Server
Field Client
Wireless
•Standard RTK
•Enhanced RTK
•Smart Client
Supports RTCM, CMR and CMR+ RTK Formats
Platform Independent
RTK Clients Operating in OCRTN
Trimble 5700
Leica SR530
Ashtech Z-Extreme
Geodetics Smart
Client
RTD-Pro Demo
RTD
Reference Network
Hardware Independent
Real-Time
Demo
Advantages over Single Baseline RTK
Overhead: Reference station infrastructure fixed and supported
Availability: Eliminates single point of failure
Reliability: Enables multiple determination for high reliability
Accuracy: Extended range (50 km)
Initialization/Re-initialization: Instantaneous with EBE
Security: No need to attend reference stations
Productivity/Efficiency: high (see all of the above)
Flexibility: Mixing of receivers/antennas handled by system
Advantages
over
Single
Baseline
RTK
Network RTK Benefits
•
Multiple Beneficiaries (for example)
• Surveyors
• GIS Data Collectors
• City Services (Fleet Management/Asset Tracking)
•
•
•
•
•
Get More Work Done With Same Crew Size
Autonomous Field Crews
Reference Coordinates are Known/Controlled by System Operator
Potential Revenue Generator
The System could pay for itself within one or two years through increased
efficiency, reduced labor, and savings related to hardware purchases
Geodetics Client RTK





Client computes Epoch-by-Epoch™
(instantaneous) solutions.
Multiple simultaneous baselines
computed.
Utilizes any reference receiver (does not
require RTK software).
Can utilize L1 only receivers on short
baselines ( < 5km).
Epoch-by-Epoch™ technology with
Carlson SurvCE will provide a
Works on laptops, tablet PC’s and
Turnkey surveying solution with
network connectivity.
PDA’s.
Solution: Network RTK with
Geodetics RTD software


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Integer-cycle phase ambiguities are resolved
independently at each epoch for a network of GPS
receivers.
Relative site positions estimated to cm-precision with only
a single epoch of GPS data from 5 or more satellites,
providing “true” RTK.
Special treatment of atmospheric effects on client allows
extended range several times the maximum distance
achieved by RTK systems. Uses “real” reference stations.
Nothing “virtual” about it.
Other Features

Designed specifically
environments.
for
real-time
wireless
networked

Works with geodetic-quality GPS receivers (dual and single
frequency).

Accuracy gracefully degraded based on GPS data availability at
each epoch.

Precise relative positioning of moving platforms (no base station
required).
Epoch-by-Epoch™ vs Traditional RTK


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Immediate (one-epoch) initialization and re- initialization vs.
15 seconds to several minutes, for ambiguity fixing.
Unaffected by cycle-slips and constellation changes.
Easier to detect and reject erroneous data points
Multiple vs. single base receiver operations
Extended range
RTD-Postprocessing
Postprocess
Demo
RTD-Vector
Vector
Demo
Deformation Monitoring in New Zealand
Geodetics’ RTD software with Epoch-byEpoch™ positioning was used to analyze the
New Zealand National GPS Network with a
spatial extent of ~ 1500 km. The network
spans the North and South Islands, with a
maximum site separation of 500 km.
The following are the analysis results:
 Single epoch precision is comparable to
networks of smaller extent (1-2 cm in the
horizontal, 5-10 cm in the vertical).
 The scatter of the hourly medians is well
below 1 cm in the horizontal components and
1-2 cm in the vertical.
 The Epoch-by-Epoch™ troposphere
estimates are very clean.
 The number of outliers (> 3 s) is very small
for the entire data set (about 0.1%).
24 hour RTD solution
Dam Deformation: Diamond Valley Lake
Largest water reservoir in southern
California - 6 mo. emergency water
supply.
 Three earthen dams
 7 Leica receivers sampling at 1 Hz
 Maximum distance 8 km
 Data streaming by radio modems
 Real-time instantaneous solutions
with RTD, with alarming features.
 Internet accessible

Raw data and photo courtesy of Mike Duffy and
Cecilia Whitaker, Metropolitan Water District of
Southern California
Competition RTD vs. VRS
Feature
Operation - Time to fix
RTD
Epoch-by-Epoch™ Instantaneous
VRS
Rapid Static 15sec – 4min
(depends on rover RTK)
Operation – Extended range
Up to 50Km baseline with L1/L2. Up
to 5Km with L1 only
Unclear
Robustness - Simultaneous
computation of multiple
baselines
Yes (limited by bandwidth)
No
Robustness - Base station
movement assumption
Yes
No - Assumed fixed base
station coordinates
Price - Independent of number
of clients
Yes
No
Applications - Suitable for
dynamic applications (UPS,
trash collection, AVL etc…)
Yes. Epoch-by-Epoch™ is ideally
suited to dynamic applications
Not optimal.
RTD Installations (partial list)
Minimum System Requirements
•
•
One Reference Station With Data Link to Central Processing Facility
(maximum 30 stations). Modem/DSL/TCP/Radio
RTD Processing Server (Windows NT, 2000, XP)
• 1 GHz Processor, 512 MB RAM, 40 GB HD, Windows
•
•
•
Communications from client to server (wireless modem –
GSM/CDPD/GPRS)
Optional for extended range, Epoch-by-Epoch™ positioning: PDA with
Geodetics Smart Client.
Additional sites can be added to existing network easily.
Geodetics, Inc. provides Epoch-by-Epoch™
positioning and navigation products for
extended range, high-precision, real-time
applications
www.geodetics.com
Tel: (858) 729-0872