Nordic nRF9151 Satellite NTN Network

This guide provides the steps to connect the Nordic nRF9151-SMA Development Kit to Skylo satellite Non-Terrestrial Networks (NTN) using a Monogoto SIM.

Quick Navigation

1. Set up the nRF9151DK

2. Connect the nRF9151 to Skylo

3. Test the connection by sending UDP payload

4. Useful Links

Set up the nRF9151DK

1. Connect the USB cable to the nRF9151DK

2. Connect the LTE antenna

3. Connect the GPS antenna

4. Insert the Monogoto SIM

Run the latest modem and application firmware

Update the nRF9151DK-SMA with the latest modem firmware which supports NTN, and use the serial_lte_modem application firmware.

How to download and update the nRF modem and application firmware

Update modem firmware

1. Download the latest modem firmware on Nordic's website, under nRF9151 SiP NTN firmware.

2. Open nRF Connect for Desktop > Programmer

3. Upload the .zip file (e.g. mfw_nrf9151-ntn_1.0.0-1.alpha.zip) to the Programmer and select Write. Don't unzip the file.

Update application firmware

1. Download the latest nRF9151 SMA DK application and modem firmware .zip file on Nordic's website (e.g. nrf9151dk_mfw-2.0.2_sdk-3.1.0).

2. Unzip the folder

3. Navigate to the directory img_app_bl

4. Find the .hex file called nrf9151dk_serial_lte_modem_202X-XX-XX_XXX.hex

5. Upload the .hex file to the Programmer and select Erase & Write.

For more information, see Nordic’s getting started page.

Open a serial connection with the nRF9151

You can use the Serial Terminal from the nRF Connect for Desktop, or any program of choice (e.g. PuTTY for Windows, or screen/minicom/miniterm for macOS/Linux).

Set the baud rate to 115200 . To test the connection with the nRF9151 modem enter AT and expect the answer OK.

Keep the AT Commands manual next to you for more details about the commands. Click here to download the latest version.

Check SIM Status

Enable the module

AT+CFUN=1

Check SIM status

AT+CPIN?

Expected response: +CPIN: READY

+CPIN: READY means that the SIM is ready and does not require any PIN entry.

Query Device Information

Useful for confirming firmware, hardware and SIM identity.

Request the firmware version

AT+CGMR

Example response: mfw_nrf9151-ntn_1.0.0-1.alpha

The minimum required modem firmware is mfw_nrf9151-ntn_1.0.0-1.alpha

Request the hardware version

AT%HWVERSION

Example response: %HWVERSION:nRF9151 LACA A1A

Request the IMSI

AT+CIMI

Request the ICCID (Integrated Circuit Card ID), which is the identification number of the SIM

AT%XICCID

Acquire GPS location

To establish a satellite connection, a location has to be set.

Put the radio in flight mode

AT+CFUN=4

Enable GNSS

AT%XSYSTEMMODE=0,0,1,0,0

Activate GPS within the nRF module

AT+CFUN=31

Start the GNSS scan

AT#XGPS=1,0,0,0

It can easily take up multiple minutes to establish an initial GNSS fix.

Example response:

#XGPS: 1,1
#XGPS: 52.089769,4.313237,56.617798,14.694924,0.126635,0.000000,"2025-11-24 18:00:31"

Save the location as we need it later on.

Shutdown the GPS

AT#XGPS=0

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Connect the nRF9151 to Skylo

Disable radio

AT+CFUN=0

Enable NTN mode (NB-IoT over satellite)

AT%XSYSTEMMODE=0,0,0,0,1

Lock the modem to one or multiple NTN satellite bands

AT%XBANDLOCK=2,,"23,255,256"

23 = Canada 255 = L band Global (US, Taiwan, Australia, New Zealand, Japan) 256 = S band Europe

Set GPS location

Format:

AT%LOCATION=<mode>,"<lat>","<long>","<alt>",<accuracy>,<validity>

Set the location which has just been acquired, e.g.:

AT%LOCATION=2,"52.08995","4.31301","16",0,0

Validate if the location was successfully set

AT%LOCATION?

Set APN

AT+CGDCONT=0,"IP","data.mono"

Subscribe to network status events

CEREG network registration status events

AT+CEREG=5

Subscribe to error codes from the network

AT+CNEC=24

Subscribe to connection state changes

AT+CSCON=3

Enable modem domain event reporting

AT%MDMEV=2

Enable the radio

AT+CFUN=1

Example responses:

%MDMEV: SEARCH STATUS 1
+CEREG: 2,"3AAE","0021CC6E",14
%MDMEV: PRACH CE-LEVEL 0
+CSCON: 1,7,4
%MDMEV: SEARCH STATUS 2
+CEREG: 5,"3AAE","0021CC6E",14,,,"11100000","00111000"

CEREG State Codes

Value	Meaning
0	Not registered, not searching
1	Registered (home network)
2	Not registered, searching
3	Registration denied
4	Unknown / out of coverage
5	Registered & roaming

Radio & Signal Checks

Check the signal quality

AT+CESQ

Example response: +CESQ: 99,99,255,255,15,53

+CESQ returns 6 values separated by commas. The last 2 values indicate the RSRQ (Reference Signal Received Quality) and RSRP (Reference Signal Received Power) respectively. RSRQ is indicated with a value between 0 and 34 , RSRP with a value be tween 0 and 97. Higher values represent better signal quality. For more details click here.

Request network info

AT%XMONITOR

Example response:

5,"","","90198","3A9D",14,255,"0007DBBD",5,228841,9,19,"","11100000","00111000","11100000"

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Test the Connection by Sending UDP Payload

To send UDP data, send three AT commands:

1. Create UDP socket

AT#XSOCKET=1,2,0

Expected response: #XSOCKET:0,2,17

1. Connect socket

Replace <ip-address> with the ip address of your UDP server

AT#XCONNECT="<ip-address>",<port>

Set the IP address and port, e.g.:

AT#XCONNECT="18.199.15.247",1055

Expected response: #XCONNECT:1

You can test the UDP connection with the Ubidots platform which runs a UDP server. Learn more.

1. Send UDP data

AT#XSEND="Hello Nordic"

Example response: #XSEND:12

1. Close the UDP socket

AT#XSOCKET=0

Expected response: #XSOCKET:0,"closed"

Great work on connecting the Nordic nRF9151-SMA DK to Monogoto! Have a look at the Things logs in the Monogoto Hub to find more details about the established connection.

Switch Between NTN and Public Networks

Use the following commands to switch from NTN to public networks:

Disable radio

AT+CFUN=0

Enable public networks

AT%XSYSTEMMODE=1,1,0,0,0

Enable radio

AT+CFUN=1

Switch Back to Satellite NTN

Disable radio

AT+CFUN=0

Enable NTN

AT%XSYSTEMMODE=0,0,0,0,1

Enable radio

AT+CFUN=1

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Useful Links

• nRF9151 NTN Evaluation Getting Started v1.1

• mfw_nrf9151-ntn AT Commands v0.4

• nRF9151_SMA_DK Hardware User Guide v0.9.0

• nRF9151_SMA_DK Antennas

• nRF91 SoftSIM API