Digital-IF, or "RF over IP", is just another way of representing spectrum. Rather than the traditional way of using Electromagnetic Spectrum, the signal is digitized at the ground site and packetized onto commodity UDP/IP messages. This allows us to move the IF around using commodity network equipment. At KSAT we have adopted this technology allowing us to use Software Signal Processing applications which allows for quicker and more standardized ground station installations.
Software signal processing capabilities
By digitizing the RF spectrum, it can easily be transported over LAN, WAN and secured MPLS or VPN networks allowing for new and creative distributed ground station architectures. Applications such as Diversity Combining become much simpler in a digital world. Each sample of the RF spectrum is accompanied by a time-stamp. These time stamps can easily be lined up from various antenna sites and recombined to create a stronger diversity combined signal.
“We have made an investment in this new technology to provide flexible architecture solutions to our customers. It allows us to use software signal processing capabilities in our ground station” says John Heskett, Systems Architect at KSAT. He continues: “If the customer has sensitivity to that signal processing, we can move that digital-IF for TT&C applications to a consolidated processing center that the customers feel is more secure".
Distributed architecture for resiliency and security
Digitizing the RF spectrum requires significant network bandwidth. For example, digitizing a 3MHz TT&C signal requires about 48Mbps of bandwidth, however digitizing a 300MHz payload signal requires about 480Mbps of continuous bandwidth. This bandwidth requirement for payload processing applications limits the application to LAN networks from a cost effectiveness standpoint. However, for TT&C applications, 40-50Mbps is well within current LAN, WAN and long-haul capabilities which has truly opened up the possibilities for distributed ground station architectures allowing us to come up with creative architectures to address resiliency, redundancy and security.
Image: John Heskett, Systems Architect at KSAT in conversation with Hennes Henniger, Director optical solutions.