The Dc-8 Data System: David Van Gilst Nserc

The DC-8 Data System

David Van Gilst NSERC

The System Now 

The current DC-8 Data system was created in 2007, as a replacement for the previous ICATS data system. −

Ethernet replaced RS-232 and coaxial video cables.

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Redundant fiberoptic gigabit ethernet network for transmission of most data. 

Access points throughout the aircraft, under the overhead bins.

REVEAL/NASDAT 

REVEAL is one of the most important components of the data system. −

Provides a standard interface between flightcritical systems on the aircraft and the experimenters and the rest of the data system.

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Sends Telemetry to the ground via Iridium

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Provides a 1Hz UDP packet in the IWG1 Data format

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Being replaced by the next generation NASDAT from the Airborne Science

IWG1 Data Format 

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A series of comma separated values provided in a 1Hz UDP packet. A product of the Interagency Working Group for Airborne Data and Telementry Standards Standard values include aircraft position and attitude data, cabin pressure, temperature, humidity, etc.

Timing 

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Instruments frequently need accurate timing information, for which the DC-8 provides two options: −

IRIG-B is 100 Pulse per second, BCD encoded signal that operates over a dedicated coaxial cable.

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NTP is a network-based protocol running over Ethernet

Both are served from a GPS based time server.

Iridium Communications 

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The Iridium Satellite constellation was launched in the late 90's to provide worldwide phone service. −

66 Satellites

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11 Orbits

The DC-8 features a multichannel Iridium system for worldwide data communications. −

4+ modems at 2400 bps.

Iridium Communications 2 

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4-6 channels, 9600 bps to 14.4 bps. Provides limited weather data and chat capabilities.

INMARSAT Communications 

In addition to the Iridium communications, the DC-8 will soon get an INMARSAT Swift Broadband system. −

Delivers up to 432kbps.

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Only works between 70 and 70.

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3 Satellite constellation 

Requires a pointable or phased array antenna.

Video 

DC-8 features 4 facility video cameras. −

1 Nadir camera, running at 1600x1200 at 10Hz.

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1 Forward camera, running at 640x480 at 10Hz.

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2 Cameras in the cargo pits for safety purposes. These are not recorded.

Situational Awareness Web App 

The DC-8 data system provides a Web application for in-flight situational awareness and decision support. −

Tables of parameters, strip charts, displays of navigation software, video cameras.

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Live data display from instruments.

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Google Earth based displays.