Unmanned Systems Technology 014 | Quantum Tron | Radio links and telemetry | Unmanned Aerial Vehicles | Protonex fuel cell | Ancillary systems | AUVSI 2017 Show report

40 This has already been demonstrated on a UAV that can be altered to act as a cellular base station in the air for disaster zones. The UAV’s payload can be reconfigured for different cellular technologies – 2G, 3G or 4G – and different bands depending on the country. Some developers are focusing on the SDR element with an FPGA and multiple antennas in a ‘multiple in multiple out’ (MIMO) configuration and connecting to the off-the-shelf radio environment that runs on standard processor boards. The SDR system can be easily programmed with a graphics design tool that outputs the bitstream to programme the FPGA, which simplifies the development cycle. A typical SDR system supports a 2 x 2 MIMO antenna (that is, with two receiving antennas and two transmitting ones) operating at up to 3.8 GHz and with a 28 MHz bandwidth. A large FPGA with QAM64 quadrature modulation and OFDM can support 4K video streams with a latency of 75 µs for the roundtrip between the UAV and the ground. On the RF side, a field-programmable RF transceiver can provide continuous coverage between 100 kHz and 3.8 GHz, with a 120 MHz RF bandwidth. The transceiver contains two transmit and two receive chains to enable the 2 × 2 MIMO, and supports 3G and 4G as well as wi-fi, Zigbee and Bluetooth. All this gives the payload designer flexibility to change the radio link depending on the applications and the conditions of operation. Encryption The security of radio links is an increasingly important topic, particularly for UAVs where the feed can be intercepted, highlighting the need to encrypt the video data on the UAV before it is transmitted rather than at the ground station. Current systems can use the Advanced Encryption Standard (AES), which was established by the US National Institute of Standards and Technology (NIST) in 2001 and is included in the ISO/IEC 18033-3 standard for IT security. The latest versions of AES, with 128- bit and 256-bit encryption keys, can be implemented on FPGAs or high-end microprocessors in large UAV systems. Smaller microcontrollers are also adding hardware blocks for AES encryption so that they can be used in smaller UAV and UGV designs, but the system relies on sharing the keys, which can be intercepted. Quantum encryption is also being viewed with interest. This relies on the property of two entangled photons of light: if one is intercepted, the other also changes. This provides a way of preventing interference with comms. June/July 2017 | Unmanned Systems Technology Focus | Radio links and telemetry THE NETHERLANDS NXP Semiconductor – www.nxp.com SWITZERLAND ID Quantique +41 22 301 83 71 wwww.idquantique.com   UK BAE Systems – www.baesystems.com Cobham +44 (0) 1628 472072 www.cobham.com KETS Quantum Security – kets-quantum.com USA Amimon – www.amimon.com Rajant Corporation +1 484 595 0233 www.rajant.com Microchip +1 480 792 7200 www.microchip.com Microsemi +1 800 713 4113 www.microsemi.com Examples of radio links and telemetry manufacturers and suppliers SDR has been demonstrated on a UAV that can be altered to act as a cellular base in the air for disaster zones. Its payload can be configured for 2G, 3G or 4G