A contextual lightweight arithmetic coder is proposed for lossless compression of medical imagery. Context definition uses causal data from previous symbols coded, an inexpensive yet efficient approach. To further reduce the computational cost, a binary arithmetic coder with fixed-length codewords is adopted, thus avoiding the normalization procedure common in most implementations, and the probability of each context is estimated through bitwise operations. Experimental results are provided for several medical images and compared against state-of-the-art coding techniques, yielding on average improvements between nearly 0.1 and 0.2 bps.

When communicating with spacecrafts, the international standard is to use the protocols defined by CCSDS. In this study, the Space Packet Protocol from CCSDS is converted to the Digital Recording Standard used in aviation. The goal of the study is to find out in what way such a conversion can be made, as well as analyzing the efficiency of different packing methods for the Digital Recording Standard. An application is developed in order to perform the conversion, and the performance of said application is profiled using different packet sizes. In the end the results are evaluated and an optimal packet size is found in terms of runtime and memory usage. In the end we conclude that a packet size of 216 bytes is best when prioritizing speed, and a packet size of 219 bytes is best when prioritizing memory.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / CCSDS Space Link Extension (SLE) Services enable the ground segment assets of space agencies to interoperate, allowing for ground stations and space data users to interact without the need for ad hoc, complicated gateways designed specifically for each new mission. Their goal is to reduce the development, management, and operational costs of providing cross support between space organizations for exchange of tracking, telemetry, and command (TT&C) data. SLE services are actively supporting over a dozen spacecraft, with many more planned over the next few years. This paper first presents an overview of the underlying SLE architecture, as defined in the SLE Reference Model. The SLE data transfer services, which move data between mission facilities and ground stations are defined, along with the management services that enable missions to make requests for ground station services. Next, up-to-date status of the testing, prototyping, and implementation of SLE services over the past few years is presented, as well as plans for adoption of SLE services by a number of space networks and space mission organizations. Finally, efforts to adapt SLE services to support legacy missions are briefly described.

International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California / The Consultative Committee for Space Data Systems (CCSDS) is developing a set of communications protocols for Advanced Orbiting Systems (AOS). The National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) are cooperating in an effort to extensively validate these AOS protocols. This paper describes the techniques and facilities being used to perform this validation. Validation of the AOS protocols consists of (1) developing a formal specification of the protocols using a standard formal definition technique (FDT), (2) developing implementations of the protocols, and (3) remote testing of the implementations. From the FDT specifications, each agency is developing independent implementations which are consistent with the FDT specifications of the AOS protocols. Errors, omissions, or discrepancies detected during the development of the FDT specification and the implementation will be reported to the CCSDS and changes to the main specification will be suggested. The independent implementations will be extensively tested locally by the developing agency and then remotely tested through a cooperative test setup between the agencies. The implementations will interact to communicate between the agencies thus providing proof that the FDT specifications are sufficiently specific to be interpreted by everyone in the same way. Significant variations in the interpretations will result in feedback to the CCSDS and any needed changes to the main specification will be suggested. The AOS protocols are divided into four categories: Path, Space Link ARQ Protocol (SLAP), Space Link (SL), and Management. Each agency has agreed to be either the leader or support agency for each of the categories. NASA has agreed to be leader for the validation of the SLAP and SLS categories while ESA has agreed to lead in the validation of the Path and Management categories. Testbeds at the European Space Research and Technology Centre (ESTEC) in Noordwijk, Holland and at the MITRE Corporation in McLean, Virginia have been constructed for the development of FDT specifications and AOS protocol implementations. Communications facilities are being obtained which will connect these testbeds. This paper describes these testbeds, the AOS FDT specifications, the protocol implementations being developed, and the results expected from the tests performed.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper describes the new Telemetry Processor Hardware (TPH) that Avtec Systems has developed for the Deep Space Network (DSN) Telemetry Processor (TLP) system. Avtec is providing the Telemetry Processor Hardware to RTLogic! for integration into the Telemetry Processor system. The Deep Space Network (DSN) is an international network of antennas that supports interplanetary spacecraft missions for exploration of the solar system and the universe. The Jet Propulsion Laboratory manages the DSN for NASA. The TLP system provides the capability to acquire, process, decode and distribute deep space probe and Earth orbiter telemetry data. The new TLP systems will be deployed at each of the three deep-space communications facilities placed approximately 120 degrees apart around the world: at Goldstone, California; near Madrid, Spain; and near Canberra, Australia. The Telemetry Processor Hardware (TPH) supports both CCSDS and TDM telemetry data formats. The TPH performs the following processing steps: soft-symbol input selection and measurement; convolutional decoding; routing to external decoders; time tagging; frame synchronization; derandomization; and Reed-Solomon decoding. The TPH consists of a VME Viterbi Decoder/MCD III Interface board (VM-7001) and a PCI-mezzanine Frame Synchronizer/Reed-Solomon Decoder (PMC- 6130-J) board. The new Telemetry Processor Hardware is implemented using the latest Field Programmable Gate Array (FPGA) technology to provide the density and speed to meet the current requirements as well as the flexibility to accommodate processing enhancements in the future.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper describes a Multi-Function Telemetry Input Module (TIM). The TIM module includes a 30 Mbps PCM frame synchronizer, a time code translator/generator, a PCM simulator and a tunable bit synchronizer all on a single PCI card. The module uses a generic architecture including: high density Field Programmable Gate Arrays (FPGAs), look-up table memory, dual port A/B data buffer memory and a full function PCI interface. The FPGA and the logic function of the card are downloadable via the PCI interface. This allows a single module to support many hardware functions in a telemetry front-end. The TIM is an integral part of a PC-based Advanced Telemetry Processing and Display System. This concept for hardware design ushers in a new generation of flexible downloadable telemetry products.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / Satellite Control Systems require a front-end component which performs real-time telemetry acquisition and command output. This paper will describe a fully networked, PC-based telemetry and command front-end which supports multiple streams and is based on Commercial Off The Shelf (COTS) technology. The front-end system is a gateway that accepts multiple telemetry streams and outputs time-tagged frame or packet data over a network to workstations in a distributed satellite control and analysis system. The system also includes a command gateway that accepts input from a command processor and outputs serial commands to the uplink. The front-end can be controlled locally or remotely via the network using Simple Network Management Protocol. Key elements of the front-end system are the Avtec MONARCH-E™ PCI-based CCSDS/TDM Telemetry Processor/Simulator board, a network-based, distributed computing architecture, and the Windows NT operating system. The PC-based telemetry and command gateway is useful throughout the lifecycle of a satellite system. During development, integration, and test, the front-end system can be used as a test tool in a distributed test environment. During operations, the system is installed at remote ground stations, with network links back to operations center(s) for telemetry and command processing and analysis.

International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / There has been much interest recently in the possibility of using the NASA Tracking and Data Relay Satellite System (TDRSS) instead of proprietary ground stations in supporting small space payload communications. These payloads operate on fairly low power and do not use the sophisticated tracking equipment standard on more complex user spacecraft. This paper is part of a feasibility study for such use of TDRSS, and focuses on the effect of the method of providing the Grade-2 data link layer services specified in Consultative Committee for Space Data Systems (CCSDS) Advanced Orbiting Systems (AOS) recommendations upon a hypothetical spacecraft using a MIL-STD-1553B polled data bus as the backbone of its onboard LAN. In particular, one case in which the 1553B bus controller, assumed to be some Intel 80X86 microprocessor, provides all CCSDS services will be contrasted with another where these services are split between the bus controller and a device which interfaces between the spacecraft LAN and the TDRSS Return Service spacelink. The comparison will be made for a 15 orbit/day scenario using a small helical antenna with a comparatively wide beamwidth. The main performance criteria considered here are end-to-end data throughput and expected delays, along with required buffer sizes for the LAN. Also, it may be noted that the data rate of the TDRSS return link and the size of the sliding window used for flow and error control will have a large impact on the required values for the chosen criteria, and so choices for these parameters significantly affect the outcome of any system service comparison. The two LAN types will be modeled and analyzed using NETWORK II.5. This simulator allows tracking of the number of packets read into LAN memories and sent down from the payload to ground via TDRSS, as well as accurately modeling the delays involved with data processing and transmission over the link.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper presents the Mission Integrated Decommutation and Analysis System (MIDAS), a multi-threaded, multi-processing application developed in Microsoft Visual C++ for Windows NT by the Air Force Development Test Center (AFDTC) Eglin AFB, Florida. The primary function of MIDAS is to support post-test processing of instrumentation data by decommutating, logging, and reporting MIL-STD-1553B or pulse code modulated (PCM) encoded data extracted from MARS-II digital tape recordings. MIDAS processes multiple data streams from a single recording, and can process multiple recordings in parallel. MIDAS also serves as a diagnostics tool for investigating data processing anomalies reported during normal production runs. MIDAS is part of an integrated suite of applications developed to provide AFDTC development test and operational test customers with quickly delivered, high-quality data products. Software development is underway to support the processing of Digital Data Acquisition and On-Board Recording Standard (DDAS) packetized telemetry data. DDAS is derived from the Consultative Committee for Space Data Systems (CCSDS) standard. [MARS-II is the digital acquisition and recording system supported by MIDAS. MARS-II was developed by DATATAPE, Incorporated, Pasadena, California. It records up to 20 gigabytes of mission data across as many as eight channels of MIL-STD-1553B or PCM encoded data. Digital recording technology provides an alternative to traditional analogbased telemetry ground systems.]

International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California / During the current decade, international cooperation in space projects has become more and more popular and this trend is increasing. Initially, this involved only single missions with agencies flying payloads on other agencies' spacecraft. Later, this trend continued with international ventures, involving different agencies. In the immediate future, even more challenging scenarios are foreseen. The best known example and prime driver for such sophisticated missions will be the Space Station Freedom and its participating partners' spacecraft. Some of the international missions (ESA missions) are described briefly in this paper, in order to set the scene for a better understanding of the complex needs for standards within advanced orbiting systems. These ventures call for efficient means for cooperation and interoperability. Part of these requirements can be met by following international standards for space communications and space data systems. The Consultative Committee for Space Data Systems (CCSDS) undertook the task of integrating the space data systems requirements and developing appropriate recommendations for data systems standards for these Advanced Orbiting Systems (AOS). All international partners in the Space Station Freedom Program participated in the definition, development, and review of the AOS recommendations. The need for better cooperation in space communications via data relay satellite prompted the formation of a three party international panel called the Space Network Interoperability Panel (SNIP). An important aspect is the need for verification and validation of the concept and of the detailed technical recommendations. For the immediate future, special compatibility campaigns, involving the international agencies are planned in order to ensure the smooth application and functioning of the AOS recommendations.