This page covers supporting information for users of New Packet Radio (NPR) 3.0 - the latest revision of the original F4HDK-invented New Packet Radio modem developed and released by Steffen D05DSH and Localino in 2025/26

By default, NPR 3.0 firmware is configured in Client mode, To establish a link, a Client and Master is required. Quick start setup for both is covered below.

All configuration is via the Ethernet port using telnet, or, via UART. Default configuration is 192.168.0.0/24, the NPR IP is 192.168.0.253 and DHCP range starts at 192.168.0.65

1. Connect an antenna or dummy load
2. Power the device using 13.8V DC
3. Connect a DHCP enabled PC to the Ethernet port
4. Open a terminal and telnet to 192.168.0.253

OR

1. Connect UART @ 961200 baud to the TX, RX and GND pins

For Windows 10, Example UART used with these these drivers, then connected using Putty

Note: If you lose IP access for any reason, you can always access NPR via UART

1. At the ready> prompt, type display config
2. Note the modulation and frequency settings, these must match the Master

When in Master mode, DHCP on the NPR Ethernet port is disabled. Follow these steps reconfigure NPR and require a local static IP is setup.

1. At the ready> prompt, type display config
2. Note the modem_IP, netmask and IP_begin
3. Type commands:
   • set is_master yes
   • save
   • reboot
4. On the connected PC or network, set a manual IP within the subnet and avoiding DHCP range starting with IP_begin, e.g. 192.168.0.20
5. Validate connectivity by re-opening the telnet connection to 192.168.0.253

1. When in RF range, NPR should connect. The CONN light will be Green on the Client and TX and RX lights flashing
2. On the Server, see who is connected by running who
3. On the Client, see connected information by running status
4. Assuming the PC connected to the Master has an IP of 192.168.0.20 and PC connected to the Client has a DHCP assigned address of 192.168.0.65, both devices should be able to ping

1. Be really careful if changing the IP configuration - set the config, check it, check it again, log it, then save and reboot
2. Set your NIC MTU to 750 to achieve reliable and consistent performance
3. You always telnet to the modem_IP, which counter-intuitively does not have to be unique on the network. In the default configuration, you would use 192.168.0.253 on all modems when connecting via telnet

Flashing the firmware in NPR 3.0 requires:

1. A Windows PC
2. Installation of the stm32_vcp_driver.zip drivers
3. A Micro-USB cable
4. The new firmware (with .nfw extension)
5. The pynpr.exe program

1. Disconnect the power supply
2. Connect the Micro-USB Cable
3. Run the upgrade using either:
   • pynpr fwflash -s COM_PORT path/to/nfw.nfw
   • pynpr fwflash -s auto path/to/nfw.nfw

NPR Commands Date: 2025-12-11 Editor: do5dsh starting from FW: localino-npr_fw25121101_hw240719

localino-npr_fw25121101 default configures 70cm band.

Download: fw25121101 and UNZIP before upgrading

Changes:

- fixed LBT mode - added runtime band selection - added RSSI threshold monitoring - TX_test mode for a maximum duration 3s

Commands:

set the RF band set band 33/70/200 for 33cm (23cm version, 70cm or 200cm)

set LBT set lbt_enabled yes/no

configure LBT threshold set lbt_rssi_threshold -40 … -105

Read out RSSI threshold of current noise floor lbt_stats

TX_test mode TX_test number_of_seconds (1..3). you need to disable the radio beforehand with “radio off”.

Original NPR Hackaday Page

Original NPR Source Files and Docs - Master

Unable to link to the Master docs using a URL - copied locally for ease of access

npr70_introduction_en_v3.6.pdf

npr_advanced_guide_v2.16.pdf

npr_specification_v2.0.pdf

Connector 1

Connector 2