What the Poster Looks Like:
System Design:
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- FIELD STATION:
- GPS Antenna to
- GPS Receiver with raw data output to
- USGS V2000 controller card to
- Radio Modem to
- Radio Antenna to
- BASE STATION:
- Radio Antenna to
- Radio Modem to
- Windows PC to
- Phone or Internet to
- Graphical Output
Trial Applications:
- Mission Peak, Fremont, California:
An ideal first site for trial application is
found at Mission Peak Landslide in Fremont,
California. A massive rock block
at the head of the landslide has intermittently
moved several decimeters
during the last several years. We installed
the system and started its operation
the end of January 2000, before
seasonal movement began.
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Antenna: Micropulse
Receiver: Canadian Marconi Allstar
OEM single frequency
Transceiver: Microwave Data Systems
MDS MHz spread spectrum
Data processing engine: Waypoint Precise DLL
Baseline length: meters
Operating schedule: Store forward
and process minutes of second
L1 data every minute intervals
Mission Peak Photo (top):
Photo above shows the massive sandstone
block with prominent tension cracks. The complete
GPS master station (MS) is on stable
ground near the ridgetop. The remote instrument
station (RS) is located downslope but
just off the block for survivability. The remote
GPS antenna (RA) is on the block and cabled
to the remote station.
Mission Peak Photo (lower right):
The lower station is located on the moving block.
Both GPS and radio antennas are on the
mast near the electronics package inside
a box with a 20 watt solar panel.
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Results for Mission Peak:
- The massive block started moving in late February,
initially moving at less than 1 cm/week then accelerated
to twice that velocity apparently in response
to periods of rainfall. The block decelerated at the
cessation of seasonal rains at the end of March,
but remained moving at a rate of 1 mm/week until late
July. About 5 cm of cumulative displacement
were detected over the 4 month period from February 1,
2000 to June 1, 2000.
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Mission Peak:
Rainfall (top); Landslide Block Movement Daily median values (bottom)
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- The inherent noise in GPS measurements can be seen in this graph (below) showing all of the individual fixed
static solutions. These typically showed repeatability +/- 1 cm horizontally and +/- 2cm vertically.
In order to better discern and visualize trends in the time-series, the median values for of a variable
number of individual static solutions were found. This simple approach was found to be very effective
in removing noise from the data and discriminating subtle movements.
Mission Peak:
Comparison of filtered and unfiltered data.
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- Near real-time data on the Internet.
Graphs of filtered and unfiltered
solutions are automatically
updated every thirty
minutes and served via phone
or network connections.
Mission Peak:
Graphs of filtered and unfiltered
solutions are automatically
updated every thirty
minutes and served via phone
or network connections.
Graph on the left shows "Last 4 months - daily average values".
Graph on the right shows "Last 2 days - ALL solutions No filtering".
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Conclusions:
- An automated GPS system for near real-time monitoring
of remote geohazards was successfully developed
and applied. The modular design uses a new low-power
controller (USGS V2000) to store and
forward raw data from a variety of GPS receivers to a
Windows-based PC that controls the remote stations
and intermittently calculates fixed static solutions.
Initial short baseline (<10 km) applications
were configured using L1-only Marconi Allstar receivers
and Waypoint Precise DLL for processing. Individual
solutions obtained twice per hour from 5-20 minutes of
10-second data showed repeatability of
1 cm horizontal and 2 cm vertical. Simple filtering by
finding median of 5 (2 hours) and 48 (24 hour)
solutions allowed clear discrimination of sub-centimeter movements.
Mount St. Helens, Washington and Augustine Island, Alaska:
- Mount St. Helens Volcano, Washington
One of three stations at Mount St. Helens volcano is located on
the dome in the crater. Access to all three remote sites is by
helicopter.
Another GPS site at Mount St. Helens is
housed in a fiberglass shelter with a small solar
panel on the roof. Inside the fiberglass
shelter is a yagi antenna, 2 batteries, and an
environmental case containing a CMC Allstar
L1 receiver, the USGS V2000 controller, and a
900 MHz spread spectrum transceiver.
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Antenna: Micropulse
Receiver: Canadian Marconi Allstar
OEM single frequency
Transceiver: Microwave Data Systems
MDS MHz spread spectrum
Data processing engine: Waypoint Precise DLL
Baseline length: 2 to 6 kilometers
Operating schedule: Store forward
and process minutes of second
L1 data every minute intervals
- Augustine Island Volcano, Alaska
Three field stations were installed on Augustine
Island Volcano in the Fall of 2000
and data are telemetered to Homer,
Alaska. This site is particularly challenging
because of difficult access, severe snow
and ice accumulations, limited solar influx
in Winter and presence of corrosive
aerosols.
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Antenna: Micropulse
Receiver: Canadian Marconi Allstar
OEM single frequency
Transceiver: Microwave Data Systems
MDS MHz spread spectrum
Data processing engine: Waypoint Precise DLL
Baseline length: 2 to 4 kilometers
Operating schedule: Store forward
and process minutes of second
L1 data every minute intervals
Transmission distance: >100 kilometers
Full-Size PDF Version:
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PDF Version
[10M,PDF]
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