New Packet Radio

New Packet Radio modem 2.0 (NPR-H 2.0)

Update: Feb 3rd, 2024 Thanks Steve to mention NPR-H in your article.

This is Version 2.0, it features up to 7 Watts TX output power!

I was amazed by the work of F4HDK. And as a ham radio guy who was active in packet radio in 1999 and the years beginning of 2000s I wanted to have something faster. Hamnet is nice, but you cannot have that long range transmissions as on 2m or 70cm bands.

The modem I build is compatible with F4HDK's hardware and firmware and can be used for ham radio guys as a standalone long range communication bridge, entrance to Ham radio, bridge between networks etc. It can handle up to 1 MBit/s data transfer between up to 8 NPR modems that communicate in 433 MHz band (70cm ham radio band). Connect a PC device to the network port of NRP-H 2.0 and the modems will handle the rest.

Additional Features

• High power PA build in, output power up to 7 Watts. Additional "OMPH!" increase the range in 70cm band. (additional GPIO Pin to drive additional power amplifiers).
• SRAM 1024K to speedup internal processing.

What do I get?

• NPR-H 2.0 PCB (The PCB hardware comes flashed and tested, shipped from Germany. You can reflash it using an ST-Link programmer. GPIO Ports are accessible on the PCB.)

Enclosure

The PCB fits into a nice aluminium 70x32x100mm enclosure from Fischer. You will need to drill holes to the sides yourself or print new sides with a 3D printer. Step files for printing are available, please ask. Please also ask for the Fischer AKG enclosure in case this is not available in your country.

Cooling

If you use it as a master and the PA in action alot its recommended to add a small cooler to the amplifier. There is space on the PCB to glue/screw a 5mm thick aluminium cooling plate onto the PCB.

Where is the firmware? I want to program myself!

If you want to programme in F4HDK's firmware, which is available and open source on hackaday please have a look on the links below.

The firmware from F4HDK does sometimes not recognize the RF chip. This behaviour is also mentioned in his documentation. This can be realized once the TX LED is permanently on after boot. A workaround is to let the hardware warm up for 2 minutes then reboot.

There is new firmware in progress. you can join telegram @npr70 for latest information.

Power Supply

12V, 2A recommended. During TX the modem will draw about 0.7-1.5A, in idle it draws <150mA. Reverse polarity protection inbuild.

Links to hackaday / version 1.0

• https://hackaday.io/project/175907-npr-h-new-packet-radio-modem
• https://hackaday.io/project/164092-npr-new-packet-radio
• https://www.tindie.com/products/edit/new-packet-radio-modem-for-70cm-npr-h-ham-radio/