provide data access to sensor stations via a database management system. Abstractâ A .... Archives read and write files to safe storage (hard disk drive and external tape drive) with FTP ... This permits a public user to retrieve and insert data.
Undersea Acoustic Network Operations through a Database-Oriented Server/Client Interface C. L. Fletcher, J. A. Rice, R. K. Creber Space and Naval Warfare Systems Center, San Diego
D. L. Codiga University of Connecticut, Avery Point
Abstract― A “seaweb server” manages the network-layer operation of underwater networks employing telesonar modems. The server is a suite of software routines that operates at manned command centers ashore, afloat, submerged, or aloft. It provides an operator interface to the undersea network via gateway nodes. It handles data packets and utility packets and archives the incoming and outgoing data into a database. Through a web browser, clients access incoming data archived by the server and submit outgoing data to the server for prioritized delivery to the undersea network.
I. INTRODUCTION Telesonar is acoustic signaling in the undersea environment for command, control, communications, and navigation (C3N). Telesonar transmission channels include shallowwater environments with node-to-node separations hundreds of times greater than the water depth. Seaweb networks are organized assemblies of telesonar modems designed for networked C3N of deployable autonomous undersea systems [1]. Seaweb networks include gateway nodes with radio, acoustic, wire, or fiber links to manned command centers that may be aboard ship, submarine, aircraft, or ashore. The command centers may be geographically distant and connected to the gateway node via space satellite, spread spectrum radios, or cellular digital packet data (CDPD) modems. At these command centers, a suite of software routines collectively identified as the “seaweb server” provides a graphical user interface (Figure 1). The seaweb server manages the network-layer operations, also known as the “layer 3” operations in the Open Systems Interconnect (OSI) notional network model. At a designated master command center a “super” seaweb server manages, controls, and reconfigures the undersea network. Seaweb servers at other manned installations can perform all functions as the “super” server except they do not reconfigure the network, which is the sole responsibility of the super server. The role of the seaweb server is illustrated by a National Oceanographic Partnership Program (NOPP) project called “Front-Resolving Observation Network with Telemetry” (FRONT). The FRONT project site is located on the inner continental shelf outside Block Island Sound. Here the seaweb network provides wireless real-time delivery of subsurface measurements from multiple sparsely distributed This work sponsored by ONR 321.
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Fig. 1. Seaweb extends modern “net-centric” interconnectivity to the undersea realm. Wireless underwater networks include gateway nodes with radio, acoustic, wire, or fiber links to manned command centers where a seaweb server provides a graphical user interface. At a designated command center a seaweb “super” server manages the undersea network. All seaweb servers archive seaweb packets and provide data access to sensor stations via a database management system.
Fig. 2. The FRONT-3 network is an example of telesonar modems instrumented for real-time wireless delivery of oceanographic data. The server maintains two-way communications with the subsurface seaweb network via gateway nodes implemented on two surface buoys, including a U.S. Coast Guard navigation buoy. A modem deployed with each sensor sends data to the gateways on primary routes (white lines). Repeater nodes between ADCP sensor nodes allow for large area coverage of the sensor array. Plotted isobaths are in 10-m intervals.
instruments in the coastal ocean. The FRONT-3 network is a distributed array of acoustic Doppler current profiler (ADCP) sensor nodes combined with repeater nodes, gateway nodes, and a seaweb server (Figure 2). One gateway node is a U.S. Coast Guard navigation buoy and a second is a buoy maintained by University of Connecticut. Each is equipped with an acoustic modem interfaced to an internet-accessible CDPD modem for two-way communication between server and subsurface network. Network data flow is remotely reconfigurable with multiple paths to the server from each sensor so loss or failure of an individual node can be accommodated [2].
the network status and health. It is responsible for command and control of the acoustic network. The local acoustic network computer entryway (LANCE) - the computer where HANCC resides – sets up the file hierarchy and streams data throughout the server. Data archiving and retrieval is accomplished through the acoustic network data yoke (ANDY). ANDY is a MySQL database server providing web-based access and security to the public user via a database client oceanographic layperson liaison yoke (OLLY). ANDY may or may not reside on LANCE. OLLY fetches database data from ANDY and performs some local data filtering for specific public user use. It also sends outgoing command requests to ANDY for distribution to the acoustic network.
II. FUNCTIONAL DESCRIPTION Figure 3 is a functional block diagram showing the seaweb server interface between the seaweb network and the enduser. The hands-on acoustic network command and control (HANCC) manages the gateways and outlying local acoustic networks (LANs). HANCC, a LabVIEW™ application, provides a graphics-oriented operator interface for reporting
III. DEVELOPMENT The seaweb server’s graphical user interface is a set of LabVIEW™ virtual instruments. LabVIEW™, a graphical programming language from National Instruments, provides modularity and an extensive function library for
Fig. 3. The seaweb server has four functional elements: LANCE–Local Acoustic Network Computer Entryway, the computer where the server resides HANCC – Hands-on Acoustic Network Command & Control, the Graphical User Interface ANDY – Acoustic Network Data Yoke, the host for the database OLLY – Oceanographic Layperson Liaison Yoke, the database client
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programming scientific instrument controls and indicators. This graphical programming language utilizes virtual instruments (VIs) that can simulate an actual instrument, such as an oscilloscope. LabVIEW™ VIs can be ported to several different operating systems (Macintosh, Windows, Unix, and Linux) without losing much of its functionality.
B. Data Logging The server maintains a file hierarchy and executes database logging functions. It provides a quick and robust method of preventing data loss. LANCE performs the following functions: Creates read and write files
A Windows NT operating system originally hosted the server, but due to several untimely system crashes, and lack of access to the operating system, we ported the server to Linux. Linux is an open source operating system, which allows the user to modify the system to suit their needs. It is a true network-based multitasking operating system with a high degree of stability.
Logs all incoming data from gateway(s) into specified format Guards against file overruns and operating system limits Ensures incoming data integrity ANDY performs the following functions:
The heart of the seaweb server is a database – which archives incoming and outgoing data packets and through a prioritized query system permits the clients access to the undersea network. A fast web-integrated database administered by a single user is needed. This rules out many database applications designed for large corporations with an army of database managers. MySQL was selected to perform these important tasks - for the following reasons:
Archives read and write files to safe storage (hard disk drive and external tape drive) with FTP Sets up a message queue for outside users to send network commands Parses incoming gateway data into a database for public access
vast programming language support – C, Perl, Java, Python, and PHP
C. Data Retrieval
Linux application compatibility
The server ensures data is being sent to an authorized user.
portability – support of multiple operating systems: Unix, Linux, and Windows
ANDY performs the following functions:
integration into larger database engines, Oracle
Verifies proper user credentials
stability – NASA changed its Acquisition Internet Service from Oracle to MySQL because of its low-cost and finding it the most robust product available [3].
Handles data encryption Acknowledges a user request for ‘data available’ After successful database server/client connection, sends requested data to client
IV. OPERATIONAL DESCRIPTION A. Network Control The server manages the undersea network. Data packets and utility packets flow through the acoustic network because of the network monitoring and routing set up by HANCC.
D. Status and Monitoring
HANCC performs the following functions:
HANCC performs the following functions:
The server displays network status and informs the system administrator of any problems. Notifies command center of network problems
Maintains each gateway’s routing tables – tables of neighbor node identification numbers (IDs) indexed by the eventual destination node. The indexed value corresponds to the neighbor node ID; then the data packet is forwarded for the next hop in the network.
Returns current network configuration Replies to command center status request Displays current network status
Maintains each gateway’s neighbor tables - tables that contain node ID number, round-trip delay times, and future adaptive-modulation and routing function parameters
E. Server Control The server is a traffic cop. It prioritizes outgoing messages, keeps the data streaming, and ensures gateway connections to the acoustic network are kept alive.
Monitors network health Alters the network configuration and updates routing and neighbor tables
HANCC performs the following functions: Provides message queue prioritization
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Fig. 4. The main LabVIEW™ graphical display here shows the acoustic network from Fleet Battle Experiment India (June, 2001). From this display an operator can view incoming data and send outgoing messages.
Displays network and user requests and responses
The server links the database to the internet with an HTML format. This permits a public user to retrieve and insert data and commands into the acoustic network.
Displays network control diagrams Displays time stamped data from outside data sources
ANDY performs the following functions:
Re-establishes gateway connections, as needed
Manages the MySQL database Sets up a database server/client connection to OLLY.
F. Operator Interface
Controls and monitors seaweb server internet activity – Ethernet and TCP/IP facilitates internet interfacing
The server provides the operator a graphical user interface. Figure 4 depicts the map display from Fleet Battle Experiment India (FBE-I). From the map display an administrator views incoming data and sends telesonar data packets.
Provides data to public through web browser Grants a private user FTP access to read/write archived files
HANCC performs the following functions: Provides an active graphically-driven interface
V. CLIENT INTERFACE
Provides an automated network route changing capability
The seaweb server interfaces to seaweb clients via a database. The data can be either in ASCII or binary format. A database message queue handles outgoing messages. This is a prioritized queuing system, which takes a data request from an outside user and places it into the database. After the request has been sent to ANDY, an acknowledgment is sent to the client via OLLY. The request with a predetermined priority goes to HANCC, which sends the outgoing message to the acoustic network. An incoming message is sent from
Shows commands and data transiting through network Allows for monitoring and control of a mobile node – a submarine or unmanned undersea vehicle (UUV)
G. Web Integration
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the gateway into a read file for archiving and sent to a series of parsed database tables. These tables break out applicationspecific data, which the client retrieves with a web-based browser or FTP.
originated by two Deployable Autonomous Distributed System (DADS) sensor nodes in the FBE-I seaweb network. VII. FUTURE DEVELOPMENT Future plans for the server include implementing node localization, optimized routing algorithms, and network initialization. Certain of these functions will ultimately migrate into the water in the form of a master node capable of autonomously controlling a networked field of telesonar modems.
VI. TESTING AND DEVELOPMENT Recent telesonar sea experiments have included testing and developing the seaweb server. The Seaweb ’98, ’99, and 2000 experiments were performed in Buzzards Bay, Massachusetts with 10 to 20 telesonar network nodes and multiple RF and cellular modem-linked gateways. For Oceans 2000, a remote demonstration was made with the seaweb server controlling the Seaweb 2000 network containing 18 acoustic modems and multiple gateways. The Oceans 2000 command center accomplished remote access to multiple gateways, node-to-node ranging, time stamping and database archiving of incoming data packets, remote telesonar modem control, and scientific sensor control. Fleet Battle Experiment India (FBE-I), performed June 2001, was a comprehensive fleet demonstration that extended seaweb networking to include a submarine as an undersea mobile gateway node. FBE-I demonstrated the successful transmission and reception of Naval messages from and to a submarine at speed and depth via the seaweb server. The seaweb server also processed telesonar transmissions
REFERENCES [1] J. A. Rice, R. K. Creber, C. L. Fletcher, P. A. Baxley, D. C. Davison, and K. E. Rogers, “Seaweb underwater acoustic nets,” SSC San Diego Biennial Review, August, 2001 [2] D. L. Codiga, J. A. Rice, and P. S. Bogden, “Real-time delivery of subsurface coastal circulation measurements from distributed instruments using networked acoustic modems,” Proc. MTS/IEEE Oceans 2000 Conf., September, 2000, Providence, RI, Vol. 1, pp. 575-582 [3] P. S. Trimble, “Open minds on open source,” Federal Computer Weekly, December 4, 2000
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