Thread: Requesting decimated data

Started: 2012-05-23 18:09:17
Last activity: 2012-05-23 18:46:22
Topics: Web Services
Elizabeth Entwistle
2012-05-23 18:09:17
Hi All,

Does anyone know a way of requesting decimated broadband data, for
example BHZ data decimated to 4sps? I have tried using the ws-timeseries
url query by adding the "deci=4" option, but this only seems to retrieve
data from a select few stations.

Any help would be much appreciated!

Many thanks and best wishes,
Elizabeth.

--
Elizabeth Entwistle
PhD Student

School of GeoSciences
Grant Institute
The King's Buildings
West Mains Road
Edinburgh


The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.


  • Philip Crotwell
    2012-05-23 14:51:04
    SOD can pull data from the dataselect web service and do a decimation
    locally before saving the data.
    http://www.seis.sc.edu/sod/

    The docs for the decimate part are here:
    http://www.seis.sc.edu/sod/ingredients/decimate.html

    Philip


    On Wed, May 23, 2012 at 6:09 AM, Elizabeth Entwistle
    <E.Entwistle<at>ed.ac.uk> wrote:
    Hi All,

    Does anyone know a way of requesting decimated broadband data, for example
    BHZ data decimated to 4sps? I have tried using the ws-timeseries url query
    by adding the "deci=4" option, but this only seems to retrieve data from a
    select few stations.

    Any help would be much appreciated!

    Many thanks and best wishes,
    Elizabeth.

    --
    Elizabeth Entwistle
    PhD Student

    School of GeoSciences
    Grant Institute
    The King's Buildings
    West Mains Road
    Edinburgh


    The University of Edinburgh is a charitable body, registered in
    Scotland, with registration number SC005336.

    _______________________________________________
    webservices mailing list
    webservices<at>iris.washington.edu
    http://www.iris.washington.edu/mailman/listinfo/webservices

  • Bruce Weertman
    2012-05-23 18:34:08
    Hi Elizabeth:

    The decimation feature of ws-timeseries is only able to decimate to certain sample rates.

    As stated in the docs:
    "The sample-rate of the source divided by the given sample-rate must be factorable by 2,3,4,7."

    I see that this is a mistake, the 4 should be a 5 - will fix this ASAP <<

    For example, if the original data is 50 sps, then you will not be able to get to 4 sps since 50 / 4 = 12.5 which is not factorable by 2,3,5,7.

    However, you would be able to get to 5 sps since 50 / 5 = 5

    For a BHZ channel like net=IU, sta=ANMO, loc=00, cha=BHZ the sample rate is 20 sps
    So you could get to 5 sps since 20/ 5 = 4 and 4 is factorable by 2,
    You could also get to 4 sps since 20/4 = 5.

    In general going to 5 sps should be a safer bet than going to 4 sps.

    At some point in the future we will likely have an interpolation feature to go to arbitrary sample rates, but we're not there yet.

    In the near term, another point for improvement would be to have better error reporting. I'll take a look at this.

    Hope that helps.
    If not, please feel free to send me a list what you're requesting and I'll see if we have a problem on our end of things.

    Cheers,
    Bruce

    --------------------------------------
    Bruce R Weertman
    Software Engineer
    IRIS DMC
    1408 NE 45h St, Suite 201
    Seattle, WA 98105

    bruce<at>iris.washington.edu
    (206) 547-0393

    On May 23, 2012, at 3:09 AM, Elizabeth Entwistle wrote:

    Hi All,

    Does anyone know a way of requesting decimated broadband data, for example BHZ data decimated to 4sps? I have tried using the ws-timeseries url query by adding the "deci=4" option, but this only seems to retrieve data from a select few stations.

    Any help would be much appreciated!

    Many thanks and best wishes,
    Elizabeth.

    --
    Elizabeth Entwistle
    PhD Student

    School of GeoSciences
    Grant Institute
    The King's Buildings
    West Mains Road
    Edinburgh


    The University of Edinburgh is a charitable body, registered in
    Scotland, with registration number SC005336.

    _______________________________________________
    webservices mailing list
    webservices<at>iris.washington.edu
    http://www.iris.washington.edu/mailman/listinfo/webservices





    • Bruce Weertman
      2012-05-23 18:46:22

      On May 23, 2012, at 11:34 AM, Bruce Weertman wrote:

      Hi Elizabeth:

      The decimation feature of ws-timeseries is only able to decimate to certain sample rates.

      As stated in the docs:
      "The sample-rate of the source divided by the given sample-rate must be factorable by 2,3,4,7."

      I see that this is a mistake, the 4 should be a 5 - will fix this ASAP <<

      For example, if the original data is 50 sps, then you will not be able to get to 4 sps since 50 / 4 = 12.5 which is not factorable by 2,3,5,7.

      However, you would be able to get to 5 sps since 50 / 5 = 5


      Oops

      50 / 5 = 10 = 2 x 5

      (thanks Paul)


      For a BHZ channel like net=IU, sta=ANMO, loc=00, cha=BHZ the sample rate is 20 sps
      So you could get to 5 sps since 20/ 5 = 4 and 4 is factorable by 2,
      You could also get to 4 sps since 20/4 = 5.

      In general going to 5 sps should be a safer bet than going to 4 sps.

      At some point in the future we will likely have an interpolation feature to go to arbitrary sample rates, but we're not there yet.

      In the near term, another point for improvement would be to have better error reporting. I'll take a look at this.

      Hope that helps.
      If not, please feel free to send me a list what you're requesting and I'll see if we have a problem on our end of things.

      Cheers,
      Bruce

      --------------------------------------
      Bruce R Weertman
      Software Engineer
      IRIS DMC
      1408 NE 45h St, Suite 201
      Seattle, WA 98105

      bruce<at>iris.washington.edu
      (206) 547-0393

      On May 23, 2012, at 3:09 AM, Elizabeth Entwistle wrote:

      Hi All,

      Does anyone know a way of requesting decimated broadband data, for example BHZ data decimated to 4sps? I have tried using the ws-timeseries url query by adding the "deci=4" option, but this only seems to retrieve data from a select few stations.

      Any help would be much appreciated!

      Many thanks and best wishes,
      Elizabeth.

      --
      Elizabeth Entwistle
      PhD Student

      School of GeoSciences
      Grant Institute
      The King's Buildings
      West Mains Road
      Edinburgh


      The University of Edinburgh is a charitable body, registered in
      Scotland, with registration number SC005336.

      _______________________________________________
      webservices mailing list
      webservices<at>iris.washington.edu
      http://www.iris.washington.edu/mailman/listinfo/webservices




      _______________________________________________
      webservices mailing list
      webservices<at>iris.washington.edu
      http://www.iris.washington.edu/mailman/listinfo/webservices





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