qftrace: VNA trace parser

The qftrace parser handles the reading and processing of the network analyzer traces, containing the reflection coefficient as a function of the sweeped frequency, \(\Gamma(f)\). The basic function of the parser is to:

1. read in the raw data and create timestamped traces

2. detect the peaks in each trace (\(f_0\)) and fit the quality factor \(Q_0\)

Usage

The use of qftrace can be specified using the "parser" keyword in the schema. Further information can be specified in the "parameters" (dict):

• "tracetype" (str): The file type of the raw data file. See here for details.

• "method" (str): The fitting routine to be used to obtain \(Q_0\). See here for a list of available methods.

• "cutoff" (float): The cutoff controlling the height-based pruning. See yadg.parsers.qftrace.prune.cutoff().

• "threshold" (float): The threshold controlling gradient-based pruning. See yadg.parsers.qftrace.prune.gradient().

• "height" (float): Peak-picking parameter, determining the relative peak height of a peak.

• "distance" (float): Peak-picking parameter, determining the minimum distance between two peaks.

Provides

The primary functionality of qfromtrace is to load the chromatographic data, including determining uncertainties of the signal (y-axis), as well as explicitly populating the points in the time axis (x-axis). This raw data is stored, for each timestep, in the "raw" entry using the following format:

- raw:
    avg:             !!int  # number of scans that are averaged for each trace
    bw:                     # filter bandwith used to measure the trace
      {n: !!float, s: !!float, u: "Hz"}
    traces:
      "{{ trace_name }}":   # detector name, currently hard-coded to S11
        f:                  # frequency-axis units are always Hz
          {n: [!!float, ...], s: [!!float, ...], u: "Hz"}
        Re(Γ):              # real part of the reflection coefficient
          {n: [!!float, ...], s: [!!float, ...], u: !!str}
        Im(Γ):              # imaginary part of the reflection coefficient
          {n: [!!float, ...], s: [!!float, ...], u: !!str}

The "metadata" section is currently empty.

The fitting of \(f_0\) and \(Q_0\) to all peaks found in each trace is performed by qftrace automatically, and can be adjusted by specifying the "method" parameter and related options. The resulting data is stored in the "derived" entry in each timestep, and contains the following information:

- derived:
    "{{ trace_name }}":   # see above, currently set to S11
      f:                  # the frequencies of each peak
        {n: [!!float, ...], s: [!!float, ...], u: "Hz"}
      Q:                  # the cavity quality factors for each peak
        {n: [!!float, ...], s: [!!float, ...], u: "Hz"}