Digital Payload Research Articles

Demand-Aware Onboard Payload Processor Management for High Throughput NGSO Satellite Systems

High-Throughput Satellite (HTS) systems with digital payload technology have been identified as a key enabler to support 5G/6G high-data connectivity with wider coverage area. The satellite community has extensively explored resource allocation methods to achieve this target. Typically, these methods do not consider the intrinsic architecture of the flexible satellite digital payload, which consists of multiple processors responsible for receiving, processing, and transmitting the signals. This paper presents a demand-aware onboard processor management scheme for broadband Non-Geostationary (NGSO) satellites. In this context, we formulate an optimization problem to minimize the number of active on-board processors while meeting the system constraints and user requirements. As the problem is non-convex, we solve it in two steps. First, we transform the problem into demand-driven bandwidth allocation while fixing the number of processors. Second, using the bandwidth allocation solution, we determine the required number of processors with two methods: 1) sequential optimization with the Branch & Bound method and 2) Bin Packing with Next Fit, First Fit, and Best Fit methods. Finally, we demonstrate the proposed methods with extensive numerical results. It is shown that the Branch & Bound, Best Fit, and First Fit methods manage the processors better than the Next Fit method. Furthermore, Branch & Bound requires fewer processors than the above methods.

A novel deep reinforcement learning architecture for dynamic power and bandwidth allocation in multibeam satellites

Due to the explosive growth and dynamic change of user demand, an efficient power and bandwidth allocation algorithm is quite essential for multibeam satellites with flexible digital payloads. To suit the real-time use of the multibeam satellites communication, we build a novel deep reinforcement learning (DRL) architecture for dynamic power and bandwidth allocation. For minimizing unmet system capacity (USC), the proposed DRL architecture adopts proximal policy optimization algorithm to directly allocate the resource in continuous space. Under the proposed DRL architecture, the DRL strategy for joint power and bandwidth allocation (named as pbDRL) reaps the best USC performance in comparison with the separate power or bandwidth allocation method of pDRL and bDRL. Besides, by implementing the allocation decision determined by pbDRL into the initial population of the existing genetic algorithm (GA), we also develop another improved GA, namely drlGA. Numerical results verify that (i) pbDRL outperforms the existing GA and PSO; (ii) pbDRL achieves comparable USC performance within a significantly reduced computation time compared with the existing optimized GA method; (iii) in comparison with the other three related heuristic algorithms, drlGA derives improved USC performance within the same computation time. These results draw a conclusion that the developed pbDRL and drlGA approaches are capable to meet the requirements of high timeliness and desirable demand satisfaction, respectively.

Proposal for optical TDM system for digital payload in next generation high throughput satellites

The digital payload for next generation high throughput communication satellites is expected to reduce the operators’ CAPEX and OPEX. Photonic technologies, which have a great affinity with digital signals, have been studied in order to increase the data throughput and reduce the mass of the satellites. Here, we propose an optical time division multiplexing system for routing the signals in the digital channelizer and have conducted a feasibility study on the transmission efficiency. This system has the potential to reduce the cost, mass, and power consumption, and to improve reliability by cleaning up the switches used for routing the signals within the satellites.

Satellite Antennas and Digital Payloads for Future Communication Satellites: The quest for efficiencies and greater flexibility

The quest for more competitive space segment cost to maintain an attractive commercial proposition of satellite communication services has never been as noticeable as it is today. This is mainly because the end user is becoming more technology agnostic with a large and diverse range of services from which to choose.

Hardware design and implementation of digital payload data receiver of LAPAN-A2 satellite

LAPAN A2 is the second-generation Indonesian micro satellite which designed and developed in Indonesia. This satellite was launched in September 2015 in India as piggy-back. Orbit of this satellite is circular and near equatorial with altitude approximately 650 km. This satellite carries digital payloads such as digital space camera, Automatic Identification System (AIS) for vessel traffic, and upgrade S-Band transmitter 3 Mbps. The digital payloads of LAPAN-A2 satellite data is downloaded in Rancabungur Ground Station, which is equipped with 11 meters antenna using S-Band frequency. The data generated from the satellite is in raw format. For ensuring this missions, it needs some hardware for receiving digital payload data of LAPAN-A2 satellite. This paper describes result of design, implementation and test from the hardware for receiving digital payload data of LAPAN-A2 Satellite. The hardware uses Morph-IC FPGA using software Quartus and microcontroller ATMega128 embedded using Basic compiler-AVR, then the design and layout of printed circuit board uses Eagle Software. From the result of the hardware functionality test of hardware payload data receiver system, the hardware is capable to pass the signal from transmitter S-band around 3Mbps and forwarded to PC by using communication serial with speed 6Mbps, and is able to download digital payload of LAPAN-A2 satellite either digital space camera or AIS data. The amount of received data depends on the height of elevation and attitude of the satellite.

디지털위성중계기용 전원공급기 설계 및 구현에 대한 연구

본 연구는 디지털위성중계기용 전원공급기의 설계 및 구현에 대해 기술하였다. 위성버스의 PLDIU(: Payload Distribution and Interface Unit)와 전원공급기의 인터페이스를 제시하였고, 우주환경에 대한 WCA(: Worst Case Analysis)를 통하여 ESD(: Electro Static Discharge) 등의 발생에 대한 회로 오동작 가능성을 최소화 시켰다. 발사환경 시 발생하는 진동 및 우주 방사능에 의한 TID(: Total Ionizing Dose)에 대한 시뮬레이션을 통해 신뢰성 있는 전원공급기를 설계하였으며, 제작 후 우주환경시험을 통하여 기능 및 성능에 문제없음을 확인하였다. This study describes the design and implementation of digital Payload power supply. We materialized the interface of the PLDIU and power supply of a satellite bus, and minimized the potential for the occurrence of such erroneous operation circuit ESD through the WCA of the space environment. We designed a reliable power supply through simulation for a TID according to the vibration generated during the launch and space radiation environment, and found no problem in the function and performance through the test space environment after production.

A Robust Audio Steganographic Scheme in Time Domain (RASSTD)

Digital Steganograpic techniques hide secret messages in a cover media (mostly image, audio or video) in an imperceptible manner which cannot be detected by unintended recipient. In addition to imperceptibility, security, capacity and robustness are the other major challenges for an effective steganographic technique. This article proposes a novel steganographic method, considering maximum secrecy, high capacity and robustness against certain attacks. The method utilizes uncompressed digital audio signals as the carrier and hides different types of digital payloads (image/text/audio) in the time domain. In the process of embedding multiple payload bits (either 2 bits or 3 bits) are embedded in each of the sample values at pseudo-random positions. The pseudo-random positions are generated using a logical expression which is devised as a function of both the cover and the payload involved to make the algorithm inherently robust against potential collusion attacks. Various objective and subjective metrics have been used to measure the performance of the proposed technique. Also test results have been presented to analyse its robustness against white noise and collusion attack.

Digital Watermarking Payload Estimation Based on Human Visual System

This paper proposes the estimation method for the maximum payload on spatial domain, concentrates on digital watermarking payload in the spatial domain image, on the constraint of perceptual invisibility research, the influence under the factors in Human Visual System. The maximum payload is influenced by the factors which include the size of image, the brightness masking, contrast masking and texture masking of the image. with such as noise visibility function visual model, gets the just noticeable different value to calculate the payload of the image, finally we get the watermarking payload, test and verify it with Matlab simulation experiments.

Performance Evaluations for Super-Resolution Mosaicing on UAS Surveillance Videos

Abstract Unmanned Aircraft Systems (UAS) have been widely applied for reconnaissance and surveillance by exploiting information collected from the digital imaging payload. The super-resolution (SR) mosaicing of low-resolution (LR) UAS surveillance video frames has become a critical requirement for UAS video processing and is important for further effective image understanding. In this paper we develop a novel super-resolution framework, which does not require the construction of sparse matrices. The proposed method implements image operations in the spatial domain and applies an iterated back-projection to construct super-resolution mosaics from the overlapping UAS surveillance video frames. The Steepest Descent method, the Conjugate Gradient method and the Levenberg-Marquardt algorithm are used to numerically solve the nonlinear optimization problem for estimating a super-resolution mosaic. A quantitative performance comparison in terms of computation time and visual quality of the super-resolution mosaics through the three numerical techniques is presented.

Using low cost open source UAVs for marine wild life monitoring - Field Report

In this paper we report results on the use of low cost, open source Unmanned Aerial Vehicles (UAV) for detecting and tracking hammerhead sharks using a digital camera payload. With the prevailing increase in affordability of Unmanned Aerial Systems (UAS) these have gained a widespread appeal and use in civilian, military and academic research scenarios. Moreover these systems have become easier to setup and deploy allowing their use in projects or activities with more limited means of funding. Still, the challenge of successfully meeting the end-user's demands with an easy-to-use, low cost operational package while avoiding over-fitting issues remains. This paper explores the applicability and successfulness of an existing low cost UAS solution in tackling maritime based environmental studies, while testing its scalability potential. Furthermore while relying upon an established tool-chain, different payload configurations were fitted into the UAV. After a series of real flight tests the end-user's required data was recovered distilled and analysed. End-user feedback demonstrated an overwhelming satisfaction with UAS's capacity to meet the required goals while retaining its modularity and affordability intact.

Optical interconnects for satellite payloads: sizing up the state of the art

Broadband communication services such as high-definition TV, video on demand, and Triple Play are fueling the bandwidth appetite of individual subscribers and network-service providers. Satisfying this hunger requires a steady increase in total available bandwidth for terrestrial networks, most effectively using optical fiber. In fact, today optical fiber is the main trunk for all data traveling long distance in wideand local-area networks. Furthermore, individual customers can benefit from the huge data capacity of optical fiber by deployment of fiber to the home. Operators in the satellitetelecommunication sector face similar challenges driven by the same bandwidth demand as their terrestrial counterparts. Moreover, the limited number of orbital positions for new satellites has spurred an increase in payload data-communication capacity using an ever-increasing number of complex, multibeam active antennas and greater aggregate bandwidth. Only satellites with very large capacity, high computational density, and flexible, transparent, fully digital payload solutions can achieve affordable communication. To keep pace with these requirements, communicationsatellite designers must devise new systems requiring a total digital throughput of a few terabytes per second (Tb/s), resulting in a high-power-consuming satellite payload. An estimated 90% of the total power consumption per chip is used for off-chip communication. These factors taken together cause signal distortions in high-speed electrical data communication. For this reason, the European Space Agency commissioned us and others to carry out a literature study of interchip optical communications Figure 1. Growth in number of papers on board-level interconnects.

Optical Packet Switching: Generation, Transmission and Recovery Demonstration Using a Frequency Tone Header

We have successfully implemented in our labs the generation, transmission, detection and routing of optical packets for next generation all-optical networks ..Ultrafast switching function (mus time base) is demonstrated using a RF frequency tone as header, combined with a high-capacity digital payload, both inserted in the optical packet. The packet may propagate kilometers in the network, without degrading. At node input the optical packet header is detected and a switching control mechanism directs the packet to a prescribed output, without further opto-electric conversion. The optical circuit is noise-free, with BER results better than 10^-12 .This system is applicable to metropolitan and access WDM optical networks style.