NASA Tap

CNS Systems, Inc. is dedicated to providing communication, navigation and surveillance solutions for the commercial and military transportation industries.

A D8PSK Communications System for NASA

For more information, e-mail us at info@cnssys.com.

CNS Systems recently completed a subcontract to NASA as part of their Terminal Area Productivity (TAP) Low Visibility Landing and Surface Operations (LVLASO) program which culminated in a successful flight test and demonstration at Atlanta's Hartsfield airport in August, 1997. The Goals of the TAP/LVLASO program are to develop and demonstrate technologies that will enable VFR capacities on the surface to CAT IIIb. This project involves the addition of Differential GPS-based Automatic Dependent Surveillance (ADS) and Ground Traffic Control capability using a new high-speed D8PSK two-way data link between the tower and the cockpit.

CNS Systems developed a customized version of its CNS Ground station (CNSGS) product for this project. The CNSGS served as the ground communications controller and interface unit. It was responsible for providing the communications interface between the prototype Rockwell Collins D8PSK high speed VHF data radios and the AMASS/ASDE-3 radar system. The CNSGS managed traffic flow, converted data formats between dissimilar binary data protocols and dynamically translated map coordinate systems between WGS-84 (aircraft systems) and X-Y feet (radar).

Integration Testing at

Langley Research Center, May 20, 1997

The CNS Ground Station was assembled at NASA's Langley Research Center for a final system integration test. This version of the CNS Ground Station uses the Rockwell Collins D8PSK data link equipment. Above is the ground station equipment. The data link transmitter shown in the inset is actually behind the monitor. The pictures below show the 757 aircraft, the test pallets inside and the cockpit with the heads-up and flat panel displays, all of which are part of this study.

NASA's experimental 757 parked in the hanger at Langley Field, Hampton, Virginia. On this day it was undergoing the final equipment configuration and testing in preparation for the flight tests schedule in July and August at Atlanta's Hartsfield Airport (ATL).

This inside of the 757 is a world of electronics, engineers, technicians and pilots. In between the racks of equipment are rows of three seats on each side so the experimenters can sit with their equipment during flight trials. As I found out, however, you must get a full NASA flight suit to stay on the plane during operations. This picture doesn't show the whole story - it was taken from about 2.3 of the way back, facing forward. There is much more!

The cockpit of the aircraft was equipped with a heads-up display and a flat panel display to provide the pilot with two different views of the airport area. Airport features were displayed in 3-D based on the aircraft's known position which was derived from Differential GPS smoothed by the Inertial Navigation System. Also integrated on the display was surface radar, Mode-S multilateration data and graphical taxi route instructions provide from the ground over VHF and Mode-S data links.

Flight Testing at

Atlanta's Hartsfield Airport, August 25-29, 1997

After a week of intensive tests at Atlanta for the purpose of collecting engineering data, a series of demonstration were carried out for invited guests. Some got to ride on the aircraft while most observed from the control center in the hotel. All of the VIPs that I spoke with were very impressed by the results of the test as well as by the complexity of the systems and the teamwork shown by NASA TAP developers, both government and industry.

This is the NASA experimental 757 parked on the Mercury Air ramp on the North side of Atlanta's Hartsfield airport about an hour before the first of a series of VIP demonstration trials. If the aircraft looks more like an Eastern Airlines plane (remember Eastern?), you are right. NASA resurrected this aircraft from the desert storage yard and rebuilt much of the aircraft as a flying laboratory to support research and development projects. The goal of these projects is to make commercial air travel safer and more efficient.

The Differential GPS station and DO-217 RF data link were installed on the roof of the Renaissance Hotel adjacent to the north side of the airport. On the top floor of the hotel was the test control center which was equipped with S-band video links giving the ground controllers and guests access to on-board camera views and a copy of the cockpit map display during flight operations. In the Air Traffic Control tower's machine room was the AMASS/ASDE-3 surface surveillance radar, the CNS data communications ground station and the VHF data link equipment (D8PSK modulation, 38.5Kbps).