CORS Guidelines Giovanni Sella

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CORS GuidelinesGiovanni Sella
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• Goal
• Upgrade the quality of CORS data and accuracy of
  associated meta data
• Why Now?
• The network is mature 1 site every 150km
• - Quality versus quantity
• - L2C is here and L5 is coming
• - Galileo on its way

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National CORS Coverage
50km
25km
100km
150km
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National CORS Coverage
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CORS network is 98 volunteer i.e.
non-NGS How - Changes must be consistent with
the needs of both NGS and the site operators -
Guidelines must accommodate a diverse group of
site operators and data users
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Stability Monument and Environment Monument -
Must be able to maintain a consistent 3-D
position NOT affected by short term surface
motion or monument motion Environment - The
space around the antenna should not change No
vegetation growth, additional structures, etc.
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• Equipment
• Antennas and Receivers
• Antennas
• - currently L1 L2 will soon require L2C and L5
• radomes NOT recommended
• oriented to true North
• mark to ARP constant (Change ant. same coord.)
• Receivers
• - programmed with accurate meta-data
• - cutoff angle 5º required and 0º preferred
• - collect data from satellites with unhealthy
  status
• - collect hourly files, not daily
• - National CORS must receive raw, not RINEX, files

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Meta-data Site Log and Photographs Site Log -
Written record of all equipment ever used and
contact info for a site Including firmware,
antenna cables, new obstructions, removed
obstructions Photographs - Visual record of
equipment and monument
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Implementation Site Selection Team - Assess all
new CORS based on current guidelines and requests
changes if needed Data quality check - Revamping
all meta-data via NGS Integrated Database Same
standards National - less dense, 100km, checked
frequently, NGS distributes and permanently
archives data Cooperative - high density, checked
less frequently, site operator distributes and
archives data for at least 30 days
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CORS Metrics Individual site quality assessment
is based on a comparison to the network as a
whole, not an arbitrary standard The worst
performing sites will be encouraged to upgrade
and may be dropped from the CORS network if a
newer better site is available
Guidelines available at www.ngs.noaa.gov/CORS/Arti
cles/CORS_guidelines.pdf