Unmanned Systems Technology 038 l Skyeton Raybird-3 l Data storage l Sea-Kit X-Class USV l USVs insight l Spectronik PEM fuel cells l Blue White Robotics UVIO l Antennas l AUVSI Xponential Virtual 2021 report

38 combine the chips with the controller, with its own non-volatile storage for its firmware. However, that also needs to be low power to avoid adding to the temperature issues of the drive. Within that 5-year window of technology being similar, it is relatively easy to adapt the memory around three generations. This allows a drive combining the controller and multiple memory die to be as small as 15 x 20 mm and 1.5 mm high in a multi-chip ball grid array package that can be soldered onto a board. This can be a flip-chip package, where the ball grid is mounted on the die to assist with heat dissipation and maintain a constant temperature to avoid reliability issues. Security Security is becoming an increasingly important part of data storage architecture; no longer is it enough to have a single point of security. With multiple controllers in a memory storage unit, the firmware for each one has to be protected. If the firmware for the memory controller or system processor can be updated, that process needs to be authenticated, with a secure boot process for the processor when it starts up. For some applications the data will be stored in encrypted form, sometimes with two types of encryption or security systems such as blockchain, so reliability is an even bigger issue. If one bit fails, then an entire block of encrypted data can be unrecoverable. One such application could be for a crash data recorder to ensure that data cannot be manipulated once recorded and that there is no way to erase or manipulate the data after recording. This can use a blockchain approach that prevents data being altered to maintain a secure chain of data. While flash memory drive makers are adding security to drives with encryption accelerators in the drive controllers, the system makers integrating the drives into unmanned platforms are adding extra data encryption using encryption chips that can manage multiple drives with high-speed transfers of up to 100 Gbyte/s. This provides two layers of independent security, but then the management of the encryption keys has to be considered. This two-layer architecture allows the data moving through an unmanned system to be encrypted and the drives to be removed for analysis later. This capability, along with random number generation and other hardware blocks to reduce power consumption, is being implemented initially in a programmable FPGA and converted to a less power-hungry silicon chip design that can manage the encryption keys and access to up to 16 drives. Interfaces The interface to the memory system is also changing, moving away from the SATA interface used by magnetic disc drives and the USB interface of SD cards. Rather than soldering a memory chip onto a board and accessing each individual page of memory, the system processor now handles a range of interface protocols, with NVMe (Non- Volatile Memory Express) and PCIe (PCI Express) being the most common. NVMe has added features for solid- state storage to control the storage from the central processor, such as reporting the temperature to the host processor and allowing the host to manage the workload and performance, and balance that with the temperature. In the past, the USB or SATA interface was the performance bottleneck. Now the NVMe protocol can support multiple I/O queues, up to 64k with each queue having 64k entries. Legacy SATA interfaces can only support single queues with 32 entries. The NVMe host software can create queues, up to the maximum allowed by the NVMe controller, determined by the system June/July 2021 | Unmanned Systems Technology A flight data recorder for a large UAV (Courtesy of Curtiss-Wright) The data will be stored in encrypted form for some applications, sometimes with two types of encryption, so reliability is an even bigger issue