Frag Out! Magazine
Issue link: https://fragout.uberflip.com/i/1488818
CNR VS. SILENT NETWORK Currently operated C4ISR systems use multiple radio networks operated simultaneously (CNR), in HF, VHF, and UHF frequency ranges. In a battalion set- ting, we may speak of even several hundred radios, belonging to several networks. The realistic bandwidth of all of those networks may be estimated as 20-100 kbit/s. Total momentary radio emissions, across several bandwidths, may range from 100 to 10,000 watts. The CNR network nodes transmit the signal over relatively long periods, of at least 100 ms, or even seconds. This stems from the time needed to switch be- tween transmission and reception, and from the effective bandwidth ranging from 100 to 2,000 data bits per node. The nodes that emit the most data, using different radios, such as command vehicles, or containerized command posts, are also the ones that are the least mobile, considering how the operation of such nodes is managed. The stronger, longer, and more stationary the emission is, the easier it becomes for the enemy COMINT systems to detect and locate it. Contrary to CNR, SILENT NETWORK makes use of OFDM. This disperses the 1 W emission across a channel that is 50 to 200 times broader than the HF/VHF radio modulations used so far. The system allows a single network node to trans- fer up to 1,400 bits of data in 1.4 ms. This is not enough for the COMINT assets to locate such a source. The emission sources cannot be differentiated. They may transmit data more, or less often. The command elements may be camouflaged even more effectively by data generated at random, by other nodes, with that data not being retransmitted. Retransmission radio onboard UAVs is the node that makes the most frequent emissions in SILENT NETWORK. However, that node changes its position conti- nuously. It travels at speeds of up to 20-30 meters per second. SILENT NETWORK also makes use of frequency hopping. Every POC may be transmitted/received at a different frequency. The SILENT NETWORK solution may be used, for instance, to create a commu- nications network for an artillery squadron. A homogeneous broadband network would shorten the engagement time from dozens of seconds, to mere seconds. On average, the RF EM power output for a whole squadron would be lower than 100 mW - placing a whole unit on a level tantamount to emission levels of a single, commercial, home WiFi router. The scattering of the elements of the given unit would make locating them, based on the EM signature, even more challenging. All, short, impulse transmis- sions would also be emitted across a range of different locations. The network would also be capable of alternating with assigned communications assets, to camouflage it in wartime. ADVANCED TECHNOLOGIES