Date: Mon, 29 Dec 1997 21:07:56 GMT Server: NCSA/1.5 Content-type: text/html Last-modified: Wed, 06 Aug 1997 17:29:36 GMT Content-length: 10784 LEO-T

The Low Earth Orbiter Terminal

 

*Overview *Hardware Images *Software Images


System Overview

LEO-T was designed to solve the problem of the high cost of ground station services. It is a complete, essentially unmanned, ground station for low Earth orbiters. Its key attributes are autonomy and remote operational control.

 

Autonomy

LEO-T functions in a fully autonomous environment. The system is driven by an internal schedule containing spacecraft AOS and LOS times and maintenance events. LEO-T automatically obtains the latest orbital element sets, issues store and forward commands, configures ground equipment, tracks the spacecraft, and even delivers telemetry data to the PI, post pass.

 

Remote Operations

PI' s may log in remotely at any time to schedule new events or monitor or control the current activity of their spacecraft. All system capabilities are available remotely to the ground station administer (GSA) and appropriate PI on the internet using a standard X-session. Using the Administrative User Interface (AUI) and the EPOCH-2000 viewer (included), the GSA may start and stop operations, perform tests, or monitor the ground equipment at a LEO-T. The GSA and PI may also use the AUI to schedule events and uplink real-time commands. During a pass, LEO-T automatically establishes a TCP/IP connection to the PI and transmits telemetry and station log data. A sample TCP/IP application (written in JAVA) is provided with the system to view this data, but the PI may process the data from this connection in any way.

 

High Performance

LEO-T's main channel telemetry path is capable of a throughput of 15 Mbps. This is 3 times the basic TDM throughput rate and 1.5 times the CCSDS rate, using Rate 1/2 convolutional encoding. This design can support future expansion via a simple substitution of a small number of components to 25 Mbps.

 

Flexibility

A single LEO-T can simultaneously support more than 20 different satellites with orbits in the 175 Km to 1000 km range. Ground equipment is automatically reconfigured for the next spacecraft between passes using canned equipment setups created by the PI' s. The system is capable of processing CCSDS version 1 and 2 as well as TDM telemetry data.

Users can access the AUI and EPOCH-2000 viewer from any X-session. Any system supporting the TCP/IP protocol can function as the client for FTP uploads and downloads and the telemetry/log monitoring connection.

 

Security

The system ensures that the GSA alone is permitted to perform station administrative tasks. The PI and GSA share the authority to control specific mission-related tasks such as pass scheduling and equipment configuration.

 

Cost Efficiency

The absence of an operations crew results in a significant reduction in operating costs. Also, because LEO-T is capable of supporting multiple missions, station time can be shared and costs distributed among the member missions.


Architecture

LEO-T is based on the proven EPOCH-2000 architecture; A distributed processing environment in which all ground station activities (telemetry processing, commanding, etc.) are performed by a real-time machine, while all administrative duties and M&C are offloaded to a separate PC-based workstation. The two are connected via fast ethernet. Since the system is on the internet and the user interface is an X-Windows client, the user need not be present at the actual LEO-T workstation to control the system. An authorized user can access the LEO-T from any location in the world.


Open Standards

LEO-T supports all the current industry standards for open architectures:

VME Bus
Ethernet LAN
TCP/IP Protocol
Programming Language
UNIX/POSIX/OSF-1 Operating System
OSF Motif User Interface

Support for the VME (Versi-Modular European) bus allows LEO-T to interface with a wide variety of bit sync, frame sync, decommutator, EU (Engineering Units) converter, and command encoder cards. Click here to see the LEO-T hardware rack.


Database Driven

As with EPOCH-2000, all of the LEO-T software is database driven, allowing it to support different hardware configurations by merely modifying the database. This flexibility permits system upgrades and changes without incurring the cost of software modifications.

The RDBMS is used for offline data management only. During run-time the data definitions are obtained from flat files exported from the database and shipped to each processing node over the network. The flat files are read into memory on initialization for run-time access on each workstation. This approach ensures the best run-time performance (there are no delays from querying the database) while simultaneously providing all the traceability and accountability features of an RDBMS.


User Interface

LEO-T features an X-Windows/ Motif-compliant GUI (Graphical User Interface) which provides for easy, intuitive interaction with the system. Use of the X-Windows standard allows a user to access the GUI from any remote machine running an X-session. Click here to see examples of the user interface


Telemetry Processing

The telemetry subsystem is capable of a throughput of 15 Mbps, expandible to 25 Mbps. CCSDS versions 1 and 2 are supported, along with TDM formats. Dual receivers and bit syncs along with diversity combiner are provided for improved single downlink quality, or for processing two downlinks simultaneously. Telemetry data is stored on the LEO-T front-end processor and shipped, or pushed, post-pass, to a destination selected by the PI. This data is also available real-time on a TCP/IP for decommutation and monitoring.


Commanding

The command subsystem supports store-and-forward and real-time spacecraft commanding with COP-1 verification. PI's can issue and abort store-and forward command sets and real-time commands remotely via the LEO-T administrative user interface (AUI).


Orbit Determination

The included OASYS software module provides satellite ephemeris propagation and computes a list of candidate passes to be selected for scheduling for all supported spacecraft. Click here for additional information on OASYS.


Screen Shots

Click on the examples below for some LEO-T screen shots:


Additional Information

For further information on LEO-T features, prices, and support, contact Steve Carchedi at the address below, or email him directly.


Integral Systems, Inc.* 5000 Philadelphia Way* Suite A* Lanham MD 20706-4417 USA
Phone: (301) 731-4233* Fax: (301) 731-9606
contact sales * contact webmaster


The following are trademarks or registered trademarks:

EPOCH 2000 - Integral Systems, Inc.
OASYS - Integral Systems, Inc.
UNIX - UNIX Systems Laboratories, Inc.
Open Look - UNIX Systems Laboratories, Inc.
X-Windows - Massachusetts Institute of Technology
Motif - The Open Software Foundation, Inc.
OSF-1 - The Open Software Foundation, Inc.