SCSN Sensor Orientation Convention
1) Triaxial sensors will be oriented vertical, north-south, and
east-west with the greatest accuracy permitted by the circumstances and
in accordance with the manufacturer's recommendation. Orientations are
true and not magnetic. Field measurements of orientation generally have
an accuracy of +-2 degrees.
2) SEED orientation codes will be assigned as described in appendix A of
the SEED Manual; "Z" for vertical, "N" for N-S and "E" for E-W.
3) 1, 2, 3 will be substituted for Z, N, E for downhole sensors at sites
with surface mount sensors. This convention is kludge that should be
abandoned when location codes are fully implemented.
4) If a sensor's orientation is found to depart measurably from true
Z,N,E it will be corrected in the field. The departure will be measured
and entered into the orientation fields of the database as an epoch
ending at the time the sensor is reoriented.
5) There is no guarantee that imported data will conform to this
convention. However, the dbase entries, which are under our control,
should adhere to these rules.
Schema Convention for Sensor Orientation
1) Channel_Data.azimuth -- The azimuth of the instrument from north,
clockwise ranging from 0 to 360 degrees. When correctly oriented an N
component will have an azimuth of 0 and an E component will have an
azimuth of 90. The Z component when truly vertical has no azimuth and is
set to 0.
2) Channel_Data.dip -- The dip of the instrument, down from horizontal
ranging from -90 to 90 degrees. When correctly oriented a Z component
will have a dip of -90 and a horizontal will have a dip of 0. If the Z
component has a dip other than -90 or 90 the azimuth of the component
should also be recorded.
Seismic Station Configurations
Communication Equipment & Requirements
TriNet has the following data communication needs:
It requires moderate amounts of bandwidth
It is geographically dispersed
It involves multiple locations
It involves real-time need for information
It requires group addressing capability
It may require communications to more than one central site
It may use LAN interconnection in future applications
Frame Relay Service (FRS) meets all of these requirements.
Frame Relay Equipment
Motorola equipment is used for both the central site and for our remote locations. At the central site, we are using a Motorola 6525+, in a modulus 21 cabinet. At most of our remote sites, we are using the Motorola Vanguard 100 FRADS. At a couple of remote sites, where we have more than two data feeds over a single 56k line, we are using Motorola 6507 multi-port FRADS. The Vangaurd 300 Ether-FRAD is used with the seismic recording equipment which utilitizes TCP/IP telemetry.