nrlx

NRL eXtended — a Python CLI and library for browsing EarthScope/IRIS's Nominal Response Library (NRL v2) and building seismic instrument responses.

Quickstart

How it works, in short: nrlx keeps one local copy of IRIS's NRL catalog on your disk, you describe your instrument, and nrlx asks IRIS to build the actual response file. Three commands:

pip install nrlx

nrlx sync                                 # download the catalog (first run and refreshes); always healthy to refresh the catalog!

nrlx build --sensor-keys streckeisen,STS-2,EG3,SG1500 \
  --output station.xml                    # a real StationXML/inv file

nrlx doctor station.xml                   # sanity-check what you built

Each comma-separated key in --sensor-keys is a word that must match somewhere in the sensor's catalog entry. Too few keys? build lists every matching configuration so you can add one more. Don't know the instrument names yet? Explore first:

nrlx browse manufacturers streckeisen              # find a manufacturer by name
nrlx browse models --manufacturer streckeisen      # its models
nrlx browse configs streckeisen --element sensor   # exact configs + instconfigs

That station.xml is a real FDSN StationXML file straight from IRIS's own service - load it anywhere that reads StationXML, including obspy.read_inventory("station.xml").

Full command reference and the ifs-and-buts (dataloggers, multiple channels, output formats) are below; a fuller walkthrough is planned for the project wiki.

Install

pip install nrlx

Add nrlx[obspy] if you also want obspy available for downstream parsing of the responses nrlx builds — nrlx itself never requires it.

Concepts

Three terms cover everything nrlx does:

• Catalog -> IRIS's tree of every nominal response, organized as element (sensor / datalogger) → manufacturer → model → configuration.
• instconfig -> the exact identifier of one configuration, e.g. sensor_Streckeisen_STS-2_EG3_SG1500_LP120_STgroundVel. It is what build actually sends to IRIS. browse exists to help you find the right one.
• Local cache -> nrlx keeps one copy of the catalog on disk (under your platform cache dir) so browsing is instant and offline. sync refreshes it.

Commands

Command	What it does
nrlx status [--live]	Show version and local cache info; --live also checks connectivity.
nrlx sync	Download the current NRL catalog into the local cache.
nrlx browse <summary|elements|manufacturers|models|configs|show>	Browse the cached catalog; show <instconfig> prints one config's full parameters.
nrlx prefixes [query]	Decode the two-letter parameter codes used in instconfigs (LP, FR, FV, ...).
nrlx build	Build a sensor(+datalogger) response and save it to a file.
nrlx doctor <file>	Run structural health checks on a saved response file.

Run nrlx <command> --help for the full option list on any of these — each browse subcommand only exposes the filters that actually apply to it.

browse manufacturers/models take an optional positional query that matches that level's own name (a manufacturer name, a model name) - --element/ --manufacturer remain as flags to narrow by a parent level. browse configs is the exception: its positional query matches manufacturer, model, and instconfig at once, since a config doesn't have a single "own name." So browse models streckeisen looks for a model literally named "streckeisen" (nothing) - use browse models --manufacturer streckeisen instead - while browse configs streckeisen works directly, because configs search all three fields - plus each config's description and parameter names/values, so browse configs groundVel or browse configs "400 V/m/s" find configs by their physical parameters, not just their names.

The list views stay deliberately narrow. To see everything one configuration carries - description and every parameter (Sensitivity, Sensor_Type, corner period, ...) - use browse show:

nrlx browse show sensor_Lunitek_TELLUS_LP1_SG400_STgroundVel

Those parameter values are exactly what you can pass as build keys (next section).

If a sensor/datalogger filter in nrlx build matches more than one configuration, it lists every matching instconfig string so you can pin down the exact one with --sensor-instconfig/--datalogger-instconfig instead.

Selecting by keys instead of instconfig

Instead of hunting down the exact instconfig, describe the instrument with comma-separated --sensor-keys/--datalogger-keys (ObsPy-v1 style). Every key must match somewhere in a configuration - manufacturer, model, instconfig, description, or a parameter name or value like Sensitivity, 40Vpp, or groundVel (quote keys with spaces: --sensor-keys 'STS-2,100 Hz'). Use nrlx browse show <instconfig> to see the full parameter list you can key on. If the selection is ambiguous, nrlx lists the matching instconfigs; pick distinguishing fragments from that list as your next keys:

nrlx build \
  --sensor-keys streckeisen,STS-2,EG3,SG1500 \
  --datalogger-keys Q330HR_PG1,FR40,ADHR,LRbelow100 \
  --output station.xml

The singular repeated form also works (--sensor-key streckeisen --sensor-key STS-2 ...), and both spellings accept either style.

Candidate instconfigs are full of coded fragments like LP120, FR500, or FV10Vpp. Run nrlx prefixes (or nrlx prefixes corner to filter) to decode them — it fetches the official code table from the NRL service, e.g. LP = Long-Period Corner, FR = Final Sample Rate, FV = Full-Scale Voltage.

Multiple channels

--channels takes comma-separated channel codes. Several channels write one file per channel (station_EHZ.xml, station_EHN.xml, ...); add --merge-channels to get one StationXML inventory containing all of them (needs pip install 'nrlx[obspy]'):

nrlx build \
  --sensor-keys streckeisen,STS-2,EG3,SG1500 \
  --network XY --station MYSTN \
  --channels EHZ,EHN,EHE --merge-channels --output station.xml

Python library

Everything the CLI does is a thin layer over the nrlx package:

from nrlx import Nrlx, ResponseFormat

nrl = Nrlx.from_cache()                      # loads the catalog already on disk
# nrl = Nrlx.sync()                          # or download a fresh one first
#                                            # (first run / to refresh)

# Find and browse
nrl.catalog.search("lunitek")                # free-text across the catalog
nrl.catalog.configurations(element="sensor", manufacturer="Streckeisen")

# Combine sensor + datalogger, entirely in memory (nothing written to disk)
built = nrl.combine(
    sensor_keys=["streckeisen", "STS-2", "EG3", "SG1500"],
    datalogger_keys=["Q330HR_PG1", "FR40", "ADHR", "LRbelow100"],
)

built.content          # raw StationXML bytes
built.save("out.xml")  # write a file only when you want one

Each element can be selected by keys (resolved through the catalog) or by an exact instconfig string - and you can mix the two. The datalogger is optional; omit it for a sensor-only response.

built = nrl.combine(
    sensor_instconfig="sensor_Streckeisen_STS-2_EG3_SG1500_LP120_STgroundVel",
    datalogger_keys=["Q330HR_PG1", "FR40"],   # or datalogger_instconfig="..."
)

Passing both sensor_keys and sensor_instconfig for the same element is an error (same for the datalogger) - give exactly one.

combine() also takes the StationXML identity and validity fields — pass them and IRIS stamps them into the response instead of placeholders:

built = nrl.combine(
    sensor_keys=["streckeisen", "STS-2", "EG3", "SG1500"],
    network="XY", station="MYSTN", location="00", channel="HHZ",
    starttime="2021-01-01", endtime="2025-01-01",
)

All six are optional; omit them and the service fills in placeholders. If you'd rather not commit to StationXML naming at all, skip them and take the bare Response instead (below).

With the nrlx[obspy] extra installed, a BuiltResponse converts in memory — this is the NRL-v1-style workflow, and the way around StationXML's strict network/station/channel naming: take the bare Response and attach it to channels you build yourself, with whatever codes you need.

inv  = built.to_inventory()   # obspy Inventory
resp = built.to_response()    # bare obspy Response - no naming attached
paz  = built.to_paz()         # poles & zeros stage

from obspy.core.inventory import Channel
channel = Channel(code="HHZ", location_code="00",
                  latitude=..., longitude=..., elevation=..., depth=...,
                  response=resp)             # your naming, your inventory

Status

v0.1.0 - the first release, working end to end against the live NRL v2 service: catalog browsing, key/instconfig selection, sensor+datalogger combination, multi-channel builds with optional merging, in-memory obspy conversion, and the structural doctor check. Planned next: response format merging and conversion (dataless SEED, RESP, SAC PZ), a suggestion engine, a TUI, a web interface, and local sensor-asset management. See CHANGELOG.md for details.

Note for developers

This is pre-1.0 and the public API (both CLI flags and the Python classes in nrlx.catalog/nrlx.nrl) can still change between releases. The code favors small, immutable dataclasses with explicit constructors (Catalog.from_file, Nrlx.from_cache) over free functions passing raw dicts around — if you're extending it, follow that pattern rather than introducing a parallel one.

Deliberately out of scope for now: combining a response file you already have (e.g. a manufacturer RESP) with an NRL entry — nrlx v0.1 is strictly "NRL in, NRL out." Merging and converting arbitrary response sources (dataless SEED, RESP, SAC PZ) is the planned nrlx.response phase. Issues and PRs welcome.

Disclaimer

This project is not affiliated with EarthScope, IRIS, or the official Nominal Response Library. NRL data remains owned/maintained by its respective providers.