What is DIFI? Behind Filtronic’s new virtualised ground segment technology

 Filtronic has announced the launch of its new Digital Intermediate Frequency (DIFI) solution, designed to accelerate the virtualisation of ground segment technology in SATCOMs. But what exactly does this mean, and why does it matter? 

By Sam Cranny-Evans, editor of Calibre Defence, published on March 30, 2026. 

Filtronic launched its new DIFI solution on March 25 via a press release. The system is designed to make satellite communications software defined. It “enables secure RF-over-IP connectivity, replacing traditional analogue infrastructure with a more flexible, cloud-ready approach,” the release states. 

The phrase “software defined” is used a lot in defence, but it is seemingly most relevant in the comms space. To get an understanding of this move and Filtronic’s role, let’s start with traditional SATCOM infrastructure. 

Satellite signals are received by a ground segment, often a dish on the ground and a radio receiver. Each channel that the satellite used would need several pieces of physical hardware on the ground, as well as insulated wiring to transmit its signals. This could also mean different boxes for encryption, signal modulation, and so on. 

DIFI infrastructure replaces that physical hardware and wiring with a software application that can be run on a server. This also means that the heavy wiring can be replaced with a standard fibre optic or ethernet cable. The physical dish still exists, but it carries a DIFI-compliant digitiser, which turns the received signal into data packets. The Filtronic solution uses encrypted internet protocol (IP) packets, which means the signal is chopped into small pieces before being sent. It is also encrypted at the same time, which helps protect it from interception. 

Why is DIFI needed?

DIFI is an industry standard, technically known as IEEE-ISTO Std 4900-2021. It was introduced to replace an older standard that included a lot of different options. Because of those options, it became difficult to ensure that systems were interoperable. Filtronic states that it is, “participating in regular multi-vendor interoperability trials, reinforcing the company’s commitment to open, standards-based innovation.” So, the Filtronic DIFI solution is designed to be interoperable, or vendor agnostic. As a result, it should be compatible with a range of satellite providers. 

Another driving factor is the growth of satellite constellations and capabilities. Many governments in Europe are seeking out their own space-based ISR systems, often through partnerships with ICEYE. There is also considerable interest in building capability around low-earth orbit SATCOM – things like Starlink and Viasat. 

But more satellites mean more ground-based infrastructure is needed to talk to them and receive their data. If it was all physical, the costs of setting it up and maintaining it would be significant, according to Filtronic. Software-defined, DIFI compliant solutions could reduce those costs quite measurably. 

What does the Filtronic product offer?

This technology represents a shift toward “wideband” digital ground stations. While traditional satellite communications have operated in lower frequency ranges (like L or Ku bands), modern high-capacity satellites require the massive bandwidth available in the Ka, Q/V, E, and W bands.

To process these high-frequency signals, the hardware must be able to “see” and digitise a very wide slice of the radio spectrum at once. The Filtronic DIFI platform does this by providing six send and receive channels, as well as 2.5 GHz on instantaneous bandwidth. 

Furthermore, signals can be sampled at 8 to 14bit level, which refers to the quality of the reconstructed digital signal. More bits means higher quality. And it has a 100 Gigabit ethernet port, which is around 100 times faster than a domestic internet connection. 

The internal RF mezzanine board (a computer board within the system) allows for hardware customisation. Operators can tailor the intermediate frequency (IF) filtering specifically for Block Upconverters and Block Downconverters. This modularity means the same base platform can be adapted for different satellite missions without needing a total hardware redesign.

Calibre comment: DIFI and the future of defence

SATCOMs and satellite based reconnaissance are used to understand what is happening, and to support strikes against targets. Increasingly, SATCOM is looked to as the high bandwidth solution for multi-domain operational concepts that call for immense levels of data transfer. In all use cases, bandwidth is a likely constraint. So, it follows that the more bandwidth that is available and the easier it is to switch between frequencies, the more resilient defence can become. 

To read more of our coverage on STACOM and the satellite industry, check out the links below: 

• Kymeta launches Kestrel u5 SATCOM antenna – Calibre Defence 
• Global Invacom launches new range of SATCOM antennas built for rapid deployment 
• Lockheed provides anti-jamming payload for Japan’s SATCOM – Calibre Defence
• Calibre Interview: Helen Weedon, Satcoms Innovation Group
• Calibre interview: Bogdan Gogulan, CEO at NewSpace Capital 

The lead image shows soldiers from 2 Signal Regiment building SATCOMS equipment in Poland on 5 March 2024. DIFI could make mobile SATCOMS more agile and able to talk to different satellites. Credit: Cpl Danielle Dawson/UK MOD © Crown copyright 2024.