Telecommand

Abstract: A ground control station to control an unmanned air vehicle during a manual mode of operation includes a processing unit, a telemetry/telecommand module, a user control module, a graphical user interface, and a wireless datalink subsystem. The wireless datalink subsystem is configured for remote communication with the unmanned air vehicle. The telemetry/telecommand module is coupled to the ground control station and is configured to download onboard data from the unmanned air vehicle to the ground station, and further is configured to upload commands from the ground station to the unmanned air vehicle. The graphical user interface includes a display module that is configured to display a plurality of downloaded UAV onboard data. The user control module is coupled to the ground control station to implement user control of a plurality of control surfaces of the unmanned air vehicle during manual mode operation of said UAV via said processing unit.

Abstract: Software Defined Radio (SDR) is a key area to realise new software implementations for adaptive and reconfigurable communication systems without changing any hardware device or feature. A review on efficient use of limited bandwidth and increasing distributed satellite missions can lead to the need for a generic yet configurable communication platform that can handle multiple signals from multiple satellites with various modulation techniques, data rates and frequency bands that must be compatible to typical small satellite requirements. SDR is beneficial for space applications as it can provide the flexibility and re-configurability and this is driven by fast development times, new found heritage, reduced cost, and low mass Commercial Off-The-Shelf (COTS) components. The implementation of a combined System-On-Chip (SoC) and SDR communication platform enables additional reduction in cost as well as mass. This paper proposes a SDR architecture in which Field Programmable Gate Array (FPGA) System-on-Chip (SoC) is paired with a Radio Frequency (RF) programmable transceiver SoC to solve back-end and front-end re-configurability challenges respectively. The test-bed is aimed at implementing the signal processing software functions in both the dual-core ARM processors and associated FPGA fabric. The distribution of the functions between the FPGA fabric and dual-processor is based on profiling experiments using signal processing blocks, implemented on the development platform, in order to identify where bottlenecks exist. This paper discusses further the results from the new multi-signal / multi-satellite pipeline architecture and the subsequent bandwidth, data rate and processing requirements. Aspects of implementing and testing signal processing chains needed for CubeSat Telecommand, Telemetry and Control (TT&C) are presented together with initial results. Thus the proposed technology not only contributes for a lightweight and portable ground station but also for an on-board satellite transceiver.

Abstract: The performance of short low-density parity-check (LDPC) codes that will be included in the standard for next-generation space telecommanding is analyzed. The paper is focused on the use of a famous ordered statistics decoder known as most reliable basis (MRB) algorithm. Despite its complexity may appear prohibitive in space applications, this algorithm is shown to actually represent a realistic option for short LDPC codes, enabling significant gains over more conventional iterative algorithms. This is possible by a hybrid approach which combines the MRB decoder with an iterative decoding procedure in a sequential manner. The effect of quantization is also addressed, by considering two different quantization laws and comparing their performance. Finally, the impact of limited memory availability onboard of spacecrafts is analyzed and some solutions are proposed for efficient processing, towards a practical onboard decoder implementation.

Abstract: The satellite tracking, telemetry, and command system, or TT&C, is utilized to transmit the telemetry and telecommand data, as well as to determine the satellite orbit. It is the lifeline of a satellite, and thus its safety and reliability are of fundamental importance to the satellite. After years of development, the traditional satellite TT&C technologies are relatively mature, while there are still many open problems to be solved for long distance deep space explorers and satellite mega-constellation. In this article, we start with a brief review regarding the evolution of the TT&C system applied in space missions. Then we raise the challenges and potential solutions for the TT&C system in solar system explorations and suggest a new networked TT&C system that is suitable for large-scale satellite constellation management tasks. In the end, some potential TT&C technologies are indicated considering the future technology. In general, the goal of this article is to provide an overview to understand the motivation, challenges, methodology, and solutions of the satellite TT&C system.