Issue 37 Unmanned Systems Technology April/May 2021 Einride next-gen Pod l Battery technology l Dive Technologies AUV-Kit l UGVs insight l Vanguard EFI/ETC vee twins l Icarus Swarms l Transponders l Sonobot 5 l IDEX 2021 report

81 Transponders | Focus and tightly integrated control loops, capacitor banks, transistors and so on. As 1 W would be enough for 10-12 km of transmission range, there is a lot of motivation to update aviation standards to allow the use of such technologies. In the meantime, however, transponder companies and UAV engineers can alter their RF front ends, such as for receiving RTK GNSS signals, or transmitting higher power of up to 500 W for BVLOS testing in remote areas. Once manufactured, there are well- established standards for testing for environmental, shock, EMI and electrostatic discharge that transponder manufacturers must adhere to. Also, testing in anechoic chambers across wide ranges of frequencies and emissions is key to ensuring the RF sensitivity of transponders, as well as their resistance to external EMI, and that they do not themselves interfere with other onboard electronics. These tests are considered standard for high-end transponders, but some companies routinely go above and beyond these to examine the edge cases of what transponders must be capable of. As an example, military transponders should ideally be capable of IFF activities even when being jammed by enemy signals. The knowhow for testing this capability is not publicly available, however. As another example, weather testing might include survivability trials against 600 V shocks to see if transponders can continue working after being struck by lightning. UTM and the safety ecosystem As mentioned, the latest developments in transponder standards can be incorporated into GCSs largely through software updates. Existing GCS interfaces can be patched to display ADS-B In, ADS-B Out, FLARM and other TCAS/ ACAS data across maps of a local area, colour coded and annotated to ensure intuitive visualisations for UAV operators. And while antenna requirements have not officially changed, some GCSs now come with omnidirectional receiver systems and multi-constellation GNSS integration. That is to allow broader ranges of TCAS information to be processed, as UAV transponder signals might contain increasingly diverse packets of data depending on who builds, flies or services the aircraft. This type of arrangement allows interoperability between different transponder architectures in a given sector of airspace. Some GCS manufacturers are also designing LTE connectivity into their products, as it allows easy transmission of ADS-B, FLARM and other UTM-critical information, particularly for VLOS operations but increasingly over BVLOS distances as well. On top of this, directional sector antennas are now being offered for ground-based tracking of UAV transponders. These beamforming, mast- mounted systems have a range of up to 1000 km and across 120 º horizontally. Highly sensitive FLARM signals for example could be tracked for UAVs Unmanned Systems Technology | April/May 2021 The use of a certified GNSS system as a position source can be critical for enabling a UAV to operate in national airspaces (Courtesy of Trig Avionics) FPGAs and dynamic RF front ends can enable significant efficiency improvements in transponder designs (Courtesy of Aerobits)