Bruce Weertman
Hello webservice users,
The DMC has updated it's ws-timeseries web services.
http://www.iris.edu/ws/timeseries
---------------
Summary
---------------
The behavior of three of the existing options has been modified:
* lpfilter
* hpfilter
* bpfilter
Four new options have been added:
* envelope
* taper
* autolimits
* correct
The changes are backwards compatible with the previous version of ws-timeseries and should not break any existing client software.
The new options improve the versatility of the service and allow it to process pressure and temperature sensor data that employ polynomial
response metadata.
-----------
Details
-----------
Behavior change:
The behavior of filtering options lpfilter (low-pass filter), hpfilter (high-pass filter) and bpfilter (band-pass filter) has been
modified. These operations now retain the original DC offset by removing the mean value prior to filtering and restoring
the mean value after the filter operation is complete.
New option - envelope:
This option uses a Hilbert transform approximated by a time domain filter.
The effect of this filter can be seen by comparing the plot generated from these two links:
http://www.iris.edu/ws/timeseries/query?demean&scale=AUTO&net=IU&sta=ANMO&loc=00&cha=BHZ&start=2010-02-27T06.30.00&end=2010-02-27T10.30.00&output=plot
http://www.iris.edu/ws/timeseries/query?demean&scale=AUTO&net=IU&sta=ANMO&loc=00&cha=BHZ&start=2010-02-27T06.30.00&end=2010-02-27T10.30.00&output=plot&envelope
The first link shows a plot of an event and the second shows a plot from the same data with the envelope option applied
New option - taper:
The taper option applies a symmetric tapering function to the data. The option takes a number between 0 and 0.5
and an optional taper function type. The number represents the width of the taper relative to the length of the time series.
Available tapers types include: HANNING, HAMMING and COSINE. The taper function is typically applied before other
filtering options to reduce end-effects. Users should bear in mind, that for the ws-timeseries web service, the order in which
the filtering parameters are specified matters. Filter parameters are processed left to right.
New option - correct:
Apply instrument correction to convert to earth units. Uses either deconvolution or polynomial response correction
depending on response metadata. If the response meta data contains a stage-zero polynomial response,
then a polynomial response correction is applied. Otherwise, deconvolution is applied. This option is mutually
exclusive with the deco option. The deco option is now considered deprecated. Polynomial response
meta data is used to represent non-linear sensors and is commonly associate with atmospheric pressure and
temperature sensor data. (search for blockette 62 in http://www.iris.edu/manuals/SEED_chpt1.htm).
New option - autolimits:
The autolimits option is used to automatically determine low-pass and high-pass taper filter parameters before
applying deconvolution. The option can only be used with the correct and decon options and cannot be used
with the freqlimits parameter.
-------------------------------------
For more information about the ws-timeseries web service, please visit the help page at:
http://www.iris.edu/ws/doc/timeseries_help.htm
regards,
IRIS DMC web services team
The DMC has updated it's ws-timeseries web services.
http://www.iris.edu/ws/timeseries
---------------
Summary
---------------
The behavior of three of the existing options has been modified:
* lpfilter
* hpfilter
* bpfilter
Four new options have been added:
* envelope
* taper
* autolimits
* correct
The changes are backwards compatible with the previous version of ws-timeseries and should not break any existing client software.
The new options improve the versatility of the service and allow it to process pressure and temperature sensor data that employ polynomial
response metadata.
-----------
Details
-----------
Behavior change:
The behavior of filtering options lpfilter (low-pass filter), hpfilter (high-pass filter) and bpfilter (band-pass filter) has been
modified. These operations now retain the original DC offset by removing the mean value prior to filtering and restoring
the mean value after the filter operation is complete.
New option - envelope:
This option uses a Hilbert transform approximated by a time domain filter.
The effect of this filter can be seen by comparing the plot generated from these two links:
http://www.iris.edu/ws/timeseries/query?demean&scale=AUTO&net=IU&sta=ANMO&loc=00&cha=BHZ&start=2010-02-27T06.30.00&end=2010-02-27T10.30.00&output=plot
http://www.iris.edu/ws/timeseries/query?demean&scale=AUTO&net=IU&sta=ANMO&loc=00&cha=BHZ&start=2010-02-27T06.30.00&end=2010-02-27T10.30.00&output=plot&envelope
The first link shows a plot of an event and the second shows a plot from the same data with the envelope option applied
New option - taper:
The taper option applies a symmetric tapering function to the data. The option takes a number between 0 and 0.5
and an optional taper function type. The number represents the width of the taper relative to the length of the time series.
Available tapers types include: HANNING, HAMMING and COSINE. The taper function is typically applied before other
filtering options to reduce end-effects. Users should bear in mind, that for the ws-timeseries web service, the order in which
the filtering parameters are specified matters. Filter parameters are processed left to right.
New option - correct:
Apply instrument correction to convert to earth units. Uses either deconvolution or polynomial response correction
depending on response metadata. If the response meta data contains a stage-zero polynomial response,
then a polynomial response correction is applied. Otherwise, deconvolution is applied. This option is mutually
exclusive with the deco option. The deco option is now considered deprecated. Polynomial response
meta data is used to represent non-linear sensors and is commonly associate with atmospheric pressure and
temperature sensor data. (search for blockette 62 in http://www.iris.edu/manuals/SEED_chpt1.htm).
New option - autolimits:
The autolimits option is used to automatically determine low-pass and high-pass taper filter parameters before
applying deconvolution. The option can only be used with the correct and decon options and cannot be used
with the freqlimits parameter.
-------------------------------------
For more information about the ws-timeseries web service, please visit the help page at:
http://www.iris.edu/ws/doc/timeseries_help.htm
regards,
IRIS DMC web services team
