The IP 400 project has been referred to as ‘the Packet Radio of the 21st Century’, which is the primary vision, and the motivation is to bring a higher speed data modes that create a transport for modern-day data streams from digital radios such as DMR, D-Star, P25, and AX.25 packets.

The project defines three data modes, denoted Mode A, B and C.

Mode A (RF)	Mode B (Baseband)	Mode C (RF)
4FSK at 100Kb/s, 50Ks/sec symbol rate on the 400MHz band.	Up to 14Kb/s using OFDM on any conventional radio in the 144, 220 and 450 MHz bands.	2.56 Mb/s using the 802.15.4 (2001) specification, in the 2.95GHz band only

Mode A

The goal of mode A is a proof of concept that establishes a local mesh network and routing information. There are two components, hardware and software. The hardware is built around an STM32WL33 processor, which has an ARM Cortex processor and a built-in IEEE 802.15.4 transceiver that can work on the 400MHz band. The hardware is realized as a Pi HAT in the Pi Zero form factor, and contains firmware to create a local mesh network, and send and receive frames from the raspberry Pi. This hardware is known as the ‘mini node’.

The mesh network is built by periodically sending a ‘beacon’ frame periodically, which has data about the node such as its callsign, IP address, and location information. The location data can be static or derived from an attached GPS receiver.

Mode B

Mode B is unique to the IP 400 project, to implement a higher speed data mode that interfaces to conventional radios, by providing a baseband (mic/speaker) connection to the radio. It achieves higher speeds using a technique known as OFDM (Orthogonal Frequency Division Multiplexing), also known to as LTE on the cellular band. This mode can be used with any existing radio or repeater in either the 144, 220, 440 or 902 MHz bands. Existing analog repeaters can be upgraded by adding of a small amount of hardware, and an audio path to existing AllStarLink systems are also supported with a custom audio driver.

The hardware for this mode employs a high end microcontroller and FPGA (Field Programmable Gate Array), all of which are field upgradeable.

Mode C

Mode C is designed for repeater systems to provide a digital link using high speed OFDM technology over RF in the amateur allocation just below the public WiFi band, enabling use of consumer antennas

Software

All software generated by the project is open source, it can be found on the primary GitHub repository, a link to it can be found on the Links page. It is our goal to ensure that this remains open to encourage experimentation and development activities in the amateur community. Please join the developer group if you have something that you would like to contribute.