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Earthscope has a collection of magnetotelluric transfer functions collected and submitted by researchers from around the world. This is an example of how to visit the SPUD EMTF website, find transfer functions, download them, and create an MTH5 of transfer functions.

1. Go to the website

The SPUD EMFT website is: https://ds.iris.edu/spud/emtf

Click on the link and you should see:

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2. Select Data

From the SPUD EMTF website you have a few options to select station you want to download. There is a rectangular selector which you can use on the map. You could put in a bounding box manually, or you can search using the pull down menus.

3. Download Data

Once you have a collection of station you want to download you can either download just the EDI files or the SPUD bundle. Suggest using the Download SPUD Bundle.

Caution: If you click on **Download EDI** the EDI files that you get in return are derived from the EMTF XML files and typically have minimal metadata. If you download the SPUD bundle then will get the orignal EMTF XML and original transfer function files.
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4. Create MTH5

Once you download the transfer functions you selected you will get a .zip file. Unzip into a folder of your chosing. Now you need to make a choice of which transfer function file types you want to use. If you download the SPUD Bundle you can choose either the EMTF XML or the original transfer function file.

Below is some example code of how to make an MTH5.

Note: If you have downloaded data that spans multiple surveys you can put the transfer functions under a single survey in the MTH5 by setting the new_survey key word.
from pathlib import Path

from mtpy import MT, MTCollection
tf_path = Path("path_to_your_transfer_functions")
with MTCollection() as mc:
    # open an MTH5, be sure to set the path to where you want it.
    mc.open_collection(
        filename=Path().cwd().joinpath("your_collection.h5")
    )
    # here you can choose your file type 
    # options are ["emtfxml" | "edi" | "zmm" | "zss" | "zrr" | "j" | "avg" ]
    mc.add_tf(
        mc.make_file_list(tf_path, file_types=["edi"]),
        new_survey="new_survey_name",
    )
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