Airgain (Nimbelink) NL-SW-LTE-TG1WWG Modem Notes

In the coming weeks, I’ll be reviewing and adding support for the Airgain NL-SW-LTE-TG1WWG modem to Simple IoT for several customer applications.

This modem uses a Telit modem. Previously, we used the NL-SW-LTE-QBG96 which is based on a Quectel modem.

Airgain modems are end-device certified, which means you don’t need to get them certified by the cellular carriers to use them. Generally, we recommend you use these types of modems for low/moderate production volumes, and then if you reach high volume usage, use a solder-down module from Telit/Quectel and go through the certification process.

Below is a photo of a development kit from Symmetry Electronics.

The NL-SWDK2 development kit provides several ways to interface with the modem. From the product brief:

Developers can connect to the modem in any of three ways:
• Directly from PC to the modem’s UART port, sending AT
commands through PC terminal application
• From a microcontroller development kit that supports an
Arduino shield interface
• Through the two modem breakout headers connected to the
Skywire interface

The modem contains UFL connectors for cellular (top) and GPS (bottom) antennas.

With modem installed:

To be continued …

There are a number of ways to communicate with a modem:

  • PPP
  • Direct-IP - Sierra
  • NCM - Huawei
  • ECM
    • cdc_ether/usb0
  • MBIM - promoted by MS
  • QMI
    • qmi_wwan/wwan0

PPP is the old way to do things, and is probably adequate for a Cat-M modem, but for faster modems, and native USB protocol should be used.

In the past, I have used QMI, but it seems it requires a lot of management and hassle to configure the modem.

Airgain appears to be supporting PPP and ECM at this time and has some excellent documentation on using both of these modes:

I’m really excited about the possibility of using ECM and getting away from PPP. This could simplify modem management in SIOT edge systems.

MBIM is also used by MediaTek based chips AFAICT, its perhaps MBIM or QMI are the most common ones.

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