This python module makes it easy to interact with Signal Metadata Format (SigMF) recordings. This module works with Python 3.7+ and is distributed freely under the terms GNU Lesser GPL v3 License.

This module follows the SigMF specification html/pdf from the spec repository.

Installation

To install the latest PyPi release, install from pip:

pip install sigmf

To install the latest git release, build from source:

git clone https://github.com/sigmf/sigmf-python.git
cd sigmf-python
pip install .

Testing can be run with a variety of tools:

# pytest and coverage run locally
pytest
coverage run
# run coverage in a venv
tox run
# other useful tools
pylint sigmf tests
pytype
black
flake8

Examples

Load a SigMF archive; read all samples & metadata

import sigmf
handle = sigmf.sigmffile.fromfile('example.sigmf')
handle.read_samples() # returns all timeseries data
handle.get_global_info() # returns 'global' dictionary
handle.get_captures() # returns list of 'captures' dictionaries
handle.get_annotations() # returns list of all annotations

Verify SigMF dataset integrity & compliance

sigmf_validate example.sigmf

Load a SigMF dataset; read its annotation, metadata, and samples

from sigmf import SigMFFile, sigmffile

# Load a dataset
filename = 'logo/sigmf_logo' # extension is optional
signal = sigmffile.fromfile(filename)

# Get some metadata and all annotations
sample_rate = signal.get_global_field(SigMFFile.SAMPLE_RATE_KEY)
sample_count = signal.sample_count
signal_duration = sample_count / sample_rate
annotations = signal.get_annotations()

# Iterate over annotations
for adx, annotation in enumerate(annotations):
    annotation_start_idx = annotation[SigMFFile.START_INDEX_KEY]
    annotation_length = annotation[SigMFFile.LENGTH_INDEX_KEY]
    annotation_comment = annotation.get(SigMFFile.COMMENT_KEY, "[annotation {}]".format(adx))

    # Get capture info associated with the start of annotation
    capture = signal.get_capture_info(annotation_start_idx)
    freq_center = capture.get(SigMFFile.FREQUENCY_KEY, 0)
    freq_min = freq_center - 0.5*sample_rate
    freq_max = freq_center + 0.5*sample_rate

    # Get frequency edges of annotation (default to edges of capture)
    freq_start = annotation.get(SigMFFile.FLO_KEY)
    freq_stop = annotation.get(SigMFFile.FHI_KEY)

    # Get the samples corresponding to annotation
    samples = signal.read_samples(annotation_start_idx, annotation_length)

Create and save a Collection of SigMF Recordings from numpy arrays

First, create a single SigMF Recording and save it to disk

import datetime as dt
import numpy as np
import sigmf
from sigmf import SigMFFile
from sigmf.utils import get_data_type_str

# suppose we have an complex timeseries signal
data = np.zeros(1024, dtype=np.complex64)

# write those samples to file in cf32_le
data.tofile('example_cf32.sigmf-data')

# create the metadata
meta = SigMFFile(
    data_file='example_cf32.sigmf-data', # extension is optional
    global_info = {
        SigMFFile.DATATYPE_KEY: get_data_type_str(data),  # in this case, 'cf32_le'
        SigMFFile.SAMPLE_RATE_KEY: 48000,
        SigMFFile.AUTHOR_KEY: '[email protected]',
        SigMFFile.DESCRIPTION_KEY: 'All zero complex float32 example file.',
    }
)

# create a capture key at time index 0
meta.add_capture(0, metadata={
    SigMFFile.FREQUENCY_KEY: 915000000,
    SigMFFile.DATETIME_KEY: dt.datetime.utcnow().isoformat()+'Z',
})

# add an annotation at sample 100 with length 200 & 10 KHz width
meta.add_annotation(100, 200, metadata = {
    SigMFFile.FLO_KEY: 914995000.0,
    SigMFFile.FHI_KEY: 915005000.0,
    SigMFFile.COMMENT_KEY: 'example annotation',
})

# check for mistakes & write to disk
meta.tofile('example_cf32.sigmf-meta') # extension is optional

Now lets add another SigMF Recording and associate them with a SigMF Collection:

from sigmf import SigMFCollection

data_ci16 = np.zeros(1024, dtype=np.complex64)

#rescale and save as a complex int16 file:
data_ci16 *= pow(2, 15)
data_ci16.view(np.float32).astype(np.int16).tofile('example_ci16.sigmf-data')

# create the metadata for the second file
meta_ci16 = SigMFFile(
    data_file='example_ci16.sigmf-data', # extension is optional
    global_info = {
        SigMFFile.DATATYPE_KEY: 'ci16_le', # get_data_type_str() is only valid for numpy types
        SigMFFile.SAMPLE_RATE_KEY: 48000,
        SigMFFile.DESCRIPTION_KEY: 'All zero complex int16 file.',
    }
)
meta_ci16.add_capture(0, metadata=meta.get_capture_info(0))
meta_ci16.tofile('example_ci16.sigmf-meta')

collection = SigMFCollection(['example_cf32.sigmf-meta', 'example_ci16.sigmf-meta'],
        metadata = {'collection': {
            SigMFCollection.AUTHOR_KEY: '[email protected]',
            SigMFCollection.DESCRIPTION_KEY: 'Collection of two all zero files.',
        }
    }
)
streams = collection.get_stream_names()
sigmf = [collection.get_SigMFFile(stream) for stream in streams]
collection.tofile('example_zeros.sigmf-collection')

The SigMF Collection and its associated Recordings can now be loaded like this:

from sigmf import sigmffile
collection = sigmffile.fromfile('example_zeros')
ci16_sigmffile = collection.get_SigMFFile(stream_name='example_ci16')
cf32_sigmffile = collection.get_SigMFFile(stream_name='example_cf32')

Load a SigMF Archive and slice its data without untaring it

Since an archive is merely a tarball (uncompressed), and since there any many excellent tools for manipulating tar files, it's fairly straightforward to access the data part of a SigMF archive without un-taring it. This is a compelling feature because 1 archives make it harder for the -data and the -meta to get separated, and 2 some datasets are so large that it can be impractical (due to available disk space, or slow network speeds if the archive file resides on a network file share) or simply obnoxious to untar it first.

>>> import sigmf
>>> arc = sigmf.SigMFArchiveReader('/src/LTE.sigmf')
>>> arc.shape
(15379532,)
>>> arc.ndim
1
>>> arc[:10]
array([-20.+11.j, -21. -6.j, -17.-20.j, -13.-52.j,   0.-75.j,  22.-58.j,
        48.-44.j,  49.-60.j,  31.-56.j,  23.-47.j], dtype=complex64)

The preceeding example exhibits another feature of this approach; the archive LTE.sigmf is actually complex-int16's on disk, for which there is no corresponding type in numpy. However, the .sigmffile member keeps track of this, and converts the data to numpy.complex64 after slicing it, that is, after reading it from disk.

>>> arc.sigmffile.get_global_field(sigmf.SigMFFile.DATATYPE_KEY)
'ci16_le'

>>> arc.sigmffile._memmap.dtype
dtype('int16')

>>> arc.sigmffile._return_type
'<c8'

Another supported mode is the case where you might have an archive that is not on disk but instead is simply bytes in a python variable. Instead of needing to write this out to a temporary file before being able to read it, this can be done "in mid air" or "without touching the ground (disk)".

>>> import sigmf, io
>>> sigmf_bytes = io.BytesIO(open('/src/LTE.sigmf', 'rb').read())
>>> arc = sigmf.SigMFArchiveReader(archive_buffer=sigmf_bytes)
>>> arc[:10]
array([-20.+11.j, -21. -6.j, -17.-20.j, -13.-52.j,   0.-75.j,  22.-58.j,
        48.-44.j,  49.-60.j,  31.-56.j,  23.-47.j], dtype=complex64)

Frequently Asked Questions

Is this a GNU Radio effort?

No, this is not a GNU Radio-specific effort. This effort first emerged from a group of GNU Radio core developers, but the goal of the project to provide a standard that will be useful to anyone and everyone, regardless of tool or workflow.

Is this specific to wireless communications?

No, similar to the response, above, the goal is to create something that is generally applicable to signal processing, regardless of whether or not the application is communications related.