About

The initial HAMNET Access Protocol has been developed by Lukas Ostendorf during his master thesis at Rohde & Schwarz Munich in 2019/2020.
A first implementation is available for the ADALM Pluto SDR: HNAP4PlutoSDR.

Available material for further reading:

• Master thesis by Lukas Ostendorf: Design of a Radio Communications Protocol for HAMNET Access in the 70cm Amateur Radio Band
• Presentation: HNAP - The HAMNET Access Protocol
• Article about HNAP (deutsch)
• Talk about HNAP at the Software Defined Radio Academy 2020

Background

As of today the end user RF access to the HAMNET is often limited to line-of-sight conditions due to the use of wideband signals on the 13-cm- and above amateur radio bands. In Germany, the use of a 200 kHz wide duplex radio channel in the 70-cm band (439.700 Downlink / 434.900 Uplink) allows to overcome this issue, however no commercial off-the-shelf (COTS) solution is available at a reasonable price tag.

The open source implementation of the HAMNET Access Protocol for the ADALM Pluto SDR (HNAP4PlutoSDR) allows to interface the end user’s PC or network (using an USB-to-LAN dongle) to RF:

The community is invited to experiment and to push the project to a real-world deployable solution for end user HAMNET access on 70-cm.

Status

We are able to transfer ~350 kbit/s in the lab from one ADALM Pluto SDR to another. Connectivity to several clients is possible even with different modulation and coding schemes.

Agenda

• Implementation of a single carrier solution
• Longer distance tests with amplifiers (PTT already available through GPIO)
• Deployment of a real-world HAMNET-70 access point