# Getting a response file to use with the CSS3.0 format

**URL:** <https://discourse.obspy.org/t/getting-a-response-file-to-use-with-the-css3-0-format/1980>\
**Category:** Usage Questions\
**Created:** [July 16, 2024, 7:48am UTC](https://discourse.obspy.org/t/getting-a-response-file-to-use-with-the-css3-0-format/1980 "2024-07-16T07:48:56Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Dmitriy\_Gordienko](https://discourse.obspy.org/user_avatar/discourse.obspy.org/dmitriy_gordienko/32/846_2.png) [@Dmitriy\_Gordienko](https://discourse.obspy.org/u/Dmitriy_Gordienko)\
**Post date:** [July 16, 2024, 7:48am UTC](https://discourse.obspy.org/t/getting-a-response-file-to-use-with-the-css3-0-format/1980/1 "2024-07-16T07:48:56Z")

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Hello dear friends! I started using obspy and I need to receive data from Iris and process it. Processing is performed using the Antelope package in css3.0 format. I receive the data normally and convert it to css3.0 format. But to measure amplitude, I need to have response files in any format that is supported by css3.0.  
I receive responses using the inventory class, but I don’t understand how to convert them to the required formats. I didn’t find any documentation or description of the format.  
Thanks for any help…

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**Author:** ![megies](https://discourse.obspy.org/user_avatar/discourse.obspy.org/megies/32/9_2.png) [@megies](https://discourse.obspy.org/u/megies)\
**Post date:** [July 16, 2024, 7:50am UTC](https://discourse.obspy.org/t/getting-a-response-file-to-use-with-the-css3-0-format/1980/2 "2024-07-16T07:50:42Z")

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You can use the `.write()` method of `Inventory` to output in various file formats, listed in the docs:

> **[obspy.core.inventory.inventory.Inventory.write — ObsPy...](https://docs.obspy.org/master/packages/autogen/obspy.core.inventory.inventory.Inventory.write.html#obspy.core.inventory.inventory.Inventory.write)**

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**Author:** ![Dmitriy\_Gordienko](https://discourse.obspy.org/user_avatar/discourse.obspy.org/dmitriy_gordienko/32/846_2.png) [@Dmitriy\_Gordienko](https://discourse.obspy.org/u/Dmitriy_Gordienko)\
**Post date:** [July 16, 2024, 9:44am UTC](https://discourse.obspy.org/t/getting-a-response-file-to-use-with-the-css3-0-format/1980/3 "2024-07-16T09:44:58Z")

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Thank you Megies!  
Yes, I have seen this method. Maybe I don’t understand something, but if I use inventory.write(“dbname”, format=“CSS”) then I just get a few files with metadata, but I don’t get the response file I need. This is written in the documentation for obspy.io.css.station.\_write\_css - Any Response objects are not saved.  
If I select the SACPZ format, it is not readable by dbpick.  
Previously, we received response files from a dataless file (seed format) like this:

> Source: Seed file  
> Instrument: Titan S/N 2492
> 
> # 
> 
> 1 unknown paz unknown  
> 1.0077649893e+18 4.0000000000e-01  
> 6  
> -9.7700000000e+02 3.2800000000e+02 0.0000000000e+00 0.0000000000e+00  
> -9.7700000000e+02 -3.2800000000e+02 0.0000000000e+00 0.0000000000e+00  
> -1.4860000000e+03 2.5120000000e+03 0.0000000000e+00 0.0000000000e+00  
> -1.4860000000e+03 -2.5120000000e+03 0.0000000000e+00 0.0000000000e+00  
> -5.7360000000e+03 4.9460000000e+03 0.0000000000e+00 0.0000000000e+00  
> -5.7360000000e+03 -4.9460000000e+03 0.0000000000e+00 0.0000000000e+00  
> 1  
> -5.1500000000e+02 0.0000000000e+00 0.0000000000e+00 0.0000000000e+00  
> 2 unknown paz unknown  
> 1.0000000000e+00 4.0000000000e-01  
> 0  
> 0  
> 3 unknown paz unknown  
> 1.0000000000e+00 4.0000000000e-01  
> 0  
> 0  
> 4 unknown fir unknown  
> 3.0000000000e+04 1  
> 1  
> 1.0000000000e+00 0.0000000000e+00  
> 0  
> 5 unknown fir unknown  
> 3.0000000000e+04 20  
> 203  
> -5.1485571485e-10 0.0000000000e+00  
> -5.5038276418e-10 0.0000000000e+00  
> -6.4914790131e-10 0.0000000000e+00  
> -8.8653023091e-10 0.0000000000e+00  
> -1.3992219428e-09 0.0000000000e+00  
> …

In addition, I saw response files in fap (frequency-amplitude-period) format:

> displacement frequency for seismic array short-period  
> vertical channels  
> Freq(Hz) Amp(norm) Phase(deg) Error(amp) Error(phase)  
> theoretical 0 complete fap  
> 111  
> 0.10000 0.0062559 -103.97 0.0 0.0  
> 0.20000 0.050193 -109.54 0.0 0.0  
> 0.30000 0.16895 -117.29 0.0 0.0  
> 0.40000 0.39709 -125.91 0.0 0.0  
> 0.50000 0.76195 -135.10 0.0 0.0  
> 0.60000 1.2769 -144.70 0.0 0.0  
> 0.70000 1.9351 -154.47 0.0 0.0  
> 0.80000 2.7092 -164.10 0.0 0.0  
> 0.90000 3.5588 -173.31 0.0 0.0  
> 1.0000 4.4426 178.13 0.0 0.0  
> 1.2000 6.1941 163.43 0.0 0.0  
> 1.4000 7.8394 151.90 0.0 0.0  
> 1.6000 9.3709 142.98 0.0 0.0  
> 1.8000 10.815 136.00 0.0 0.0  
> 2.0000 12.198 130.43 0.0 0.0  
> 2.2000 13.540 125.90 0.0 0.0  
> 2.4000 14.857 122.13 0.0 0.0  
> 2.6000 16.158 118.96 0.0 0.0  
> 2.8000 17.450 116.23 0.0 0.0  
> 3.0000 18.739 113.85 0.0 0.0  
> 3.2000 20.022 111.76 0.0 0.0  
> 3.4000 21.299 109.90 0.0 0.0  
> 3.6000 22.567 108.23 0.0 0.0  
> 3.8000 23.829 106.71 0.0 0.0  
> 4.0000 25.086 105.33 0.0 0.0  
> …

Fap tables are obtained from responses in poles and zeros, but I don’t know how to do this.

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<div class="post-metadata">

**Author:** ![megies](https://discourse.obspy.org/user_avatar/discourse.obspy.org/megies/32/9_2.png) [@megies](https://discourse.obspy.org/u/megies)\
**Post date:** [July 16, 2024, 11:00am UTC](https://discourse.obspy.org/t/getting-a-response-file-to-use-with-the-css3-0-format/1980/4 "2024-07-16T11:00:22Z")

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I don’t know formats used by CSS. The first example seems to be a textual representation of all filter stages, but not sure about the conventions. In principle you could work with the `Response` objects and write out such information yourself, but that might be quite some work.

Getting a F-A-P list is straight forward. It’s probably not the most ideal approach but it’s easy to do, so maybe you can have a try with that.

e.g.

```python
from obspy import read_inventory
import numpy as np

inv = read_inventory()
response = inv[0][0][0].response
freqs = np.logspace(-3, 3, 100)
resp_cpx = response.get_evalresp_response_for_frequencies(freqs)
resp_amp = np.abs(resp_cpx)
resp_phase = np.angle(resp_cpx)
resp_phase = np.degrees(resp_phase)

```

These values you could write out to files for all your stations looping over your inventory..

```python
for net in inv:
    for sta in net:
        for cha in sta:
            resp = cha.response
            ...

```

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<div class="post-metadata">

**Author:** ![Dmitriy\_Gordienko](https://discourse.obspy.org/user_avatar/discourse.obspy.org/dmitriy_gordienko/32/846_2.png) [@Dmitriy\_Gordienko](https://discourse.obspy.org/u/Dmitriy_Gordienko)\
**Post date:** [July 16, 2024, 11:36am UTC](https://discourse.obspy.org/t/getting-a-response-file-to-use-with-the-css3-0-format/1980/5 "2024-07-16T11:36:08Z")

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Again, thank you!  
Yes, exactly, my goal is to create a response file for each station and channel, as you wrote. I have already created metadata tables in this way (site/sitechan/instrument/sensor).  
I’ll try to do it as you suggested and try to understand the format. Unfortunately there is very little information!  
If anyone has experience solving this problem, I would be very glad to communicate!