otdrparser

otdrparser is a Python library for parsing OTDR traces in Telcordia SR-4731 Version 2 format (*.sor files).

It is a simplified re-implementation of the pyOTDR project. Its author, Hsin-Yu Sidney Li, together with several others deserve a lot of credit for reverse-engineering the Telcordia SR-4731 standard as it is not freely available.

The otdrparser library differs from the pyOTDR project in multiple ways.

• It's a small module with a parse2() function (and a now legacy parse() function).
• It only supports Version 2 of the Telcordia SR-4731 standard.
• Only single-trace OTDR files are supported. Multi-trace input is rejected explicitly.
• The checksum block is read but not verified.
• No attempt is made to accomodate vendor specific blocks.
• I am certain otdrparser contains bugs. Please open a Github Issue if you find any.

Both parser functions accept any binary file-like object, including an open file or an io.BytesIO instance.

import io
import otdrparser

with open('my_trace_file.sor', 'rb') as fp:
    blocks = otdrparser.parse2(fp)

blocks_from_memory = otdrparser.parse2(io.BytesIO(sor_bytes))

• Each "block" has a name attribute which describes its type.
• The parse2() function returns the parsed trace file as a dictionary, keyed by the name of the block.
• Data points are included as a list of (distance in metres, dB) pairs.
• Data-point and key-event distances are expressed in metres. The encoded FxdParams.range field follows the SOR convention and is expressed in kilometres.
• FxdParams.averaging_time is expressed in seconds.
• Vendor proprietary blocks are included as raw bytes.
• Some data is interpreted. For example fibre_type=652 is also interpreted as "ITU-T G.652 (standard single-mode fiber)"
• Truncated, malformed, and unsupported input raises OTDRParserError.

Output of the .parse2() method converted into JSON: example-parse2.json.

The otdrparser.parse() function is now considered legacy. It returns the blocks as a list.

Output of the .parse() method converted into JSON: example-parse.json).