pynbntnmodem 0.4.1

Library for interfacing to Narrowband Non-Terrestrial Network modems using AT commands.

NB-NTN Modem Interface

A generic model for interfacing to a NB-IoT modem compatible with 3GPP R17 Non-Terrestrial Network.

Provides an base class NbntnBaseModem that abstracts specific AT commands to common methods used for communicating using NB-IoT over satellite. The class is intended to be subclassed and extended for specific modem variants from various manufacturers.

Modem Subclassing

Since modem implementations differ across make/model, this library is intended to be used to create NbntnBaseModem subclasses with specific AT commands and responses. An example DefaultModem is included which covers the most basic operations that should be supported by any 3GPP NTN compliant modem.

Initialization Sequence

The ntninit submodule describes the format and an example template for the AT command sequence required by a particular modem variant.

The ntn_init list of init objects may be customized and included at the top of a specific modem subclass.

Importing a Modem Subclass

A common approach to importing a modem subclass is as follows:

import importlib
from pkgutil import iter_modules

from pynbntnmodem import NbntnBaseModem, DefaultModem


for mod in iter_modules(modems.__path__):
    submodule = importlib.import_module(f'{path_to_module_file}')
    for attr_name in dir(submodule):
        attr = getattr(submodule, attr_name)
        if (isinstance(attr, type) and
            issubclass(attr, NbntnBaseModem) and
            attr is not DefaultModem):
            
            modem = attr()

Common Workflow

• connect() using either .env variables, default or programmatic values for SERIAL_PORT/port and SERIAL_BAUDRATE/baudrate.

• initialize_ntn() to run the modem-specific configuration sequence

• Run a loop that continually runs check_urc(), queues and then processes each get_urc_type()

URC injection

Some modems do not emit any URC on important events such as the completion of a MO message sending. In such cases the inject_urc() method is provided to simulate a modem-generated URC.