NAME
dbtc, correctdt - perform waveform and database time corrections
SYNOPSIS
dbtc [-p parfile] [-t stime] [-v]
gdb:gnet:gsta:gch
bdb:bnet:bsta:bch
correctdt [-v] [-m srcmatch] [-t stime] bdb
SUPPORT
Contributed code: NO BRTT support.
THIS PIECE OF SOFTWARE WAS CONTRIBUTED BY THE ANTELOPE USER COMMUNITY. BRTT DISCLAIMS ALL OWNERSHIP, LIABILITY, AND SUPPORT FOR THIS PIECE OF SOFTWARE.
FOR HELP WITH THIS PIECE OF SOFTWARE, PLEASE CONTACT THE CONTRIBUTING AUTHOR.
DESCRIPTION
Seismic networks can have clock problems and as a result produce
data with incorrect time.
dbtc finds time corrections for
seismic data for network (
bad data) by
cross correlating with data from a co-located station from another
network that does not have a timing
problem (
good data), writing a
tcorrection table.
correctdt reads this tcorrection table and fixes times in
the wfdisc and arrival tables.
When the data is in mini-seed format, the times
in the SEED headers are also corrected.
dbtc
dbtc needs references to both data with bad timing, and
the data with good timing. The (
bad data) segment must be specified in
the form of
bdb:
bnet:
bsta:
bch, where
bdb |
database name of data with a bad time |
bnet |
network name of data with a bad time |
bsta |
station name of data with a bad time |
bch |
channel name of data with a bad time |
Similarly, the (
good data) must be specified in form of
gdb:
gnet:
gsta:
gch,
where
gdb |
db name of data with a good time |
gnet |
network name of data with a good time |
gsta |
station name of data with a good time |
gch |
channel name of data with a good time |
dbtc makes a tcorrection table with name bdb.tcorrection and
with the following fields:
time tcor gnet gsta gchan gsamprate
bnet bsta bchan bsamprate lddate
tcor is the correction factor which needs to be added to the
bad data at time
time.
If bad data and good data have different sampling rates dbtc
does a re-sampling of bad data and then runs the cross-correlation.
correctdt
For each value of time
in the wfdisc and arrival,
correctdt looks up the tcor value for the closest prior
time in the tcorrection table and applies the tcor value as a static correction.
There is no provision at this time for linear interpolation for applying
time corrections.
OPTIONS
dbtc
-
-p parfile
Specify an alternate parameter file for dbtc.
-
-t stime
Specify time of bad data waveform from which start to do a cross correlation.
By default start at data start time.
-
-v
Be more verbose.
correctdt
-
-m srcid
tcorrection record which net_sta_chan key matches the regular
expression srcid is used in a time correction procedure.
-
-t stime
Start fixing time in bad data set at stime.
-
-v
Be more verbose.
PARAMETER FILE
dbtc uses a parameter file, which has the following parameters:
-
data_segment_window
data series are split on segments by data_segment_window seconds
and tcor is calculated for each such segment.
-
correlation_window
data window in seconds which is used in cross correlation computations.
-
allowed_time_err_offset
maximum allowed time error in seconds.
EXAMPLE
Find time correction for anza network. Bad data is data/anza:AZ:PFO:BHZ
and good data is nrdc/ida:II:PFO:shz
% dbtc nrdc/ida:II:PFO:shz data/anza:AZ:PFO:BHZ
% correctdt data/anza
AUTHOR
Marina Glushko
Antelope User Group Contributed Software