Avoiding Data Bottlenecks: High Performance Sensor Data Across a Rotary Interface
(Room 261-262)
04 May 16
11:30 AM
-
12:00 PM
Tracks:
Air, Defense, Research and Development, Technical Track: Image and Data Processing
The challenge of small, state-of-the-art gimbaled sensor systems that are common AUV payloads is transferring data speeds of Gigabit/sec+ across the rotating interface. This challenge has become one of the primary design challenges to the industry and has an important impact on system architecture. Traditionally this functionality was handled with slip rings that handled power, signal, and data transfer. This panel will discuss the options that are available and currently in development to transfer data well above a Gigabit/sec. Specific formats will be discussed including HD video, GigE (1 and 10), and other high speed data formats while addressing special requirements presented by each of these formats as well as overall system architecture. The role that real-time data compression can play in the final solution will be reviewed. Passive devices transmit signals without any signal processing and can be analyzed and specified using typical transmission line properties, e.g., signal attenuation and noise properties. The two passive components for transmitting high speed data to and from rotating platforms are slip rings and fiber optic rotary joints (FORJ). Active rotary transfer devices transmit signals using signal processing electronics to convert the signal into a form that can be transmitted across the interface and then, of course, convert them back to the original form. There is a whole family of components that use this active approach and vary the manner used to transmit the signal across the interface; however, since the transmission method is transparent to the user and the specification method is fairly universal, it is useful to consider these techniques as a single type of active component which will be referred to as a High Speed Data Link (HSDL). One of the most important data path decisions to be made is the transmission line media decision, namely copper or optical fiber. This media decision should be made on the basis of optimizing the overall system performance and not solely on the basis of the rotational interface. For example, choosing fiber as the transmission media simply because of a perception that a fiber optic rotary joint (FORJ) is the best way to transmit high speed data from a rotary platform can limit system options. On the other hand, if the decision is made that fiber is the best transmission media because of typical fiber advantages such as EMC isolation, bandwidth properties, or weight savings, then the rotary transmission device selection becomes a natural part of this decision process and an appropriate FORJ can be selected. Copper is still a useful transmission media in many high speed data applications as advanced techniques for data transmission on copper continue to expand the bandwidth of copper solutions. Collecting data with high performance sensors, converting this data to digital data streams and transmitting the data from rotating platforms to stationary processors is a challenge to system designers as the bandwidth expands into multiple Gigabit / second territory. Decisions should be made based on a survey of the overall system requirements and not just on individual components. The panel discussion will be geared toward helping system designers of scanning or rotating sensor systems make critical decisions about transmission media, data compression, and system architecture. The presentation will be broken into 5 primary. • Slip Ring: The workhorse of rotary power and data systems. Sliding electrical contacts transmit electrical signals and power. The bandwidth capability of slip rings has been significantly improved over the past 10 years and bandwidth capabilities and constraints will be discussed. • Fiber Optic Rotary Joint (FORJ): Allows the transmission of optical signals across a rotary interface. These devices have unlimited bandwidth, but there are limits on number of fiber channels and the physical configuration that will be reviewed. • High Speed Data Link (HSDL): Active data transfer devices with signal conditioning electronics and a rotary interface that can be electrical (contacting or non-contacting) or optical are a practical way to increase the bandwidth of copper media across a rotating copper interface. • Multiplexer: Allows the full utilization of the bandwidth of high speed transmission lines by combining multiple channels onto one transmission line. Time division and wave division are two common techniques. The roles of SERDES, ARM, and FPGA processors will be reviewed. • Media Converter: Electronics that convert signals from electrical to optical or the reverse are often required to optimize system solutions.