[webservices] Requesting decimated data

[Bruce Weertman]

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