The drive for increased capacity means the military can adopt commercially developed waveforms but adapt them for tighter security.
Waveforms are the software that dictate the behaviour of all software defined radios within the confines of what the hardware can do. Armed forces are increasingly reliant on waveforms that have been developed for commercial purposes, particularly in satellite communications, or are proprietary pieces of software created and owned by companies that develop tactical radios.
Clearly, therefore, these companies are as critical to nations’ defence capabilities as other privately owned developers of military equipment, as they tend to own the intellectual property and employ the human talent behind it.
While those waveforms developed purely for commercial use don’t have to contend with the variety and intensity of threats employed by military adversaries to disrupt each other’s communications, they do have to be able to fend off hacking attempts and avoid natural and human made interference and be secure enough to safeguard commercially sensitive information. Furthermore, military users can encrypt more highly classified information before it is fed into the Satcom system, so long as the intended recipients have the right keys. Their use is expanding as an inevitable consequence of the same need for capacity and bandwidth beyond what dedicated, government owned military communication systems can provide. Privately developed military waveforms are just that – dedicated military waveforms with all the required military security built in.
Both continue to evolve, expanding the number and variety of capabilities offered to users at the tactical edge.
Handheld VDL waveforms
In October of last year, Kratos RT Logic licensed its Common Data Link (CDL) waveforms to what is now L3Harris for use in the latter’s nanoSVDL radios that it is providing to the US Air Force under a five year indefinite delivery/indefinite quantity (IDIQ) contract. The service is buying them as part of an effort to develop Hand Held Video Data Link (HH-VDL) radios supporting video data links and real-time ISR communications in tactical environments where the spectrum is both crowded and contested by adversaries.
With built-in data protection and jamming resistance, Kratos’ new CDL waveforms enable mobile networks to connect ground, airborne and naval forces via multiple tactical host platforms, says the company. The family of waveforms licensed under the agreement include the Bandwidth Efficient Common Data Link (BE CDL), Standard CDL, Vortex Native Waveform (VNW), Tactical Data Link (TDL), 466-Extended Range (ER) and other tactical waveforms.
BE CDL is a government specified waveform that, as the name suggests, is optimised to minimise the amount of bandwidth it need to transmit a given amount of information and has been shown to work on small UAVs weighing less than 13.6kg (30lb).
L3Harris picked Kratos as a partner because they demonstrated the operational use of the BE-CDL waveform as part of the US Marines’ Secure CDL ISR radio and their work on waveform verification for all CDL radios with their CDL test set for a number of years. Users should be getting a Next Generation Handheld Mission Module and a standalone Video Data Link radio within months.
In February, L3Harris announced improvements to the TNW-75 international and coalition variant of the Tactical Networking Waveform, which creates a self-forming and self-healing network and provides a common operating picture with a range of up to 30km.(18.6m) The improvements include a doubling of the number of nodes in the network and adds advanced situational awareness and defensive electronic warfare capabilities. The developer emphasises that the increase from 64 to 128 nodes enables diverse company-and-below networks to be ‘flattened’ into a single 75kHz network. The advantages of this include better operational understanding, elimination of points of failure at radio-to-radio interconnections, and 25 percent reductions in the number of radios and the amount of spectrum they need.
Cognitive networking waveform
Defensive capabilities have also been programmed in to Silvus’ latest improvements to its StreamCaster Mobile Ad-hoc Networks (MANETs), using cognitive radio techniques to allow the networks to operate successfully despite hostile jamming and other sources of electromagnetic interference. Announced in January, the new feature is known as MANET Interference Avoidance (MAN-IA), and it is available as a a software upgrade to any SC4200 or SC4400 radio.
Silvus explains that MAN-IA constantly monitors frequencies and channels on all the radios in the network to assess network quality. If it detects the onset electromagnetic interference in the current channel anywhere on the network, it rapidly switches all the radios on the network to a more suitable band or channel to maintain connectivity. In a video surveillance application, for example, MAN-IA can react respond fast enough to a jammer threat to ensure that the network maintains a glitch free video stream, according to the company. This capability comes without significantly reducing network throughput, the company emphasises.
It also allows operators to configure it for specific applications through the StreamScape interface, defining channels within chosen bands and providing autonomous frequency agility over several GHz of frequency range. Additionally the interface provides the operator with a graphical representation of performance at each radio on each channel on the network, enabling sources of jamming and interference to be localised.
Inherently scalable, MAN-IA has no practical limitation in the number of nodes or the physical distance covered by the network, says the company.
Mitigation of intentional jamming and unintentional interference is also a feature of the new Warrior Robust Enhanced Network-Narrowband (WREN-NB) waveform, the development of which TrellisWare is leading for the US Army, the company announced in April. Formerly known as the Soldier Radio Waveform-Narrowband (SRW-NB), the WREN-NB is intended to be both efficient in terms of spectrum use and resilient while providing secure integrated tactical IP networking in rapidly changing environments and longer range for air and ground operations. Other key attributes are to include wide frequency coverage, massive scalability and interoperability between different radio platforms.
Single-frequency transmit & receive
Operating in crowded and contested RF environments and mitigating bandwidth limitations may be perennial problems, but they are bringing forth creative solutions, one of which is the ability to transmit and receive on the same frequency at the same time reliably. Known as Single Frequency-Simultaneous Transmit and Receive (SF-STAR), this will be a core capability of the Military Full Duplex Radio (MFDR), of which TrellisWare is also leading the development.
The company is to demonstrate two SF-STAR systems under the programme, one fixed and one mobile, it announced on 18 July. Critical to the technology is Self Interference Suppression (SIS), which is the ability to stop the relatively weak received signal from being swamped by the much more powerful transmitted signal. TrellisWare says that it aims to integrate all components and subsystems from the antenna to the modem processing to achieve 130-150 dB SIS performance for effective SF-STAR operations, and to enable the system to function between 225–2300MHz in operational environments, boosting spectral efficiency. The system is currently in field test.
Introducing such a capability into existing networks will likely require the radio to run existing waveforms, but new or adapted waveforms will probably be required to make the most of it in future.
by Peter Donaldson
Published in Tactical Radios 2019/2020 supplement.