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requires a high flexibility of signal processing implemented on complex electronic printed circuit boards. Each board
includes all the necessary functions for complete analogue signal processing (ASP) of a CCD: input clamping,
correlated double sampling, analogue and digital offset correction, 14-bit analogue to digital conversion providing a
signal dynamic range of at least 12-bit, dark signal non-uniformity (DSNU) correction and photo response non-
uniformity (PRNU) correction.
7 DIGITAL COMPUTER AND MASS MEMORY
The camera computer system consists of several components:
e camera computer as data processing platform and camera control unit
e mass memory systems as storage device for image and other mission data
e electronics of the position and orientation system
e operator and pilot interface as user control elements
« IO-Box as interface unit to other sensors and devices.
71 Camera Computer
The main component of the camera computer (figure 5) is the high-speed image data channel, designed to compress the
image data provided by the camera head in real-time. The compression supports a sustained input data rate of up to
40MB/s and features two standard compression modes: lossless and JPEG. The back end of the data channel is built by
means of a recording interface which multiplexes and spools data from different sources and formats the stream to be
stored on the mass memory system in an optimal manner. The peak performance of the recording interface reaches up
to several hundred MB/s and supports a flexible data management while storing data on to the mass memory system. In
addition to the image data channel, the camera computer contains the hardware platform for the flight and sensor
control software and features various interfaces for data exchange and communication.
Other NN Camera Computer
Interfaces |
Camera Head DPI POS
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Processing Interface (T1 System
Optics ;
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ww
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_ Operator Pilot
Interface : Interface -
Figure 5. Components and connections of the camera computer
72 Mass Memory System
The mass memory system stores all mission data, such as image, orientation and housekeeping data, collected during a
survey flight. It is based on a rugged disk array and meets the extended environmental conditions required for airborne
applications. The device allows fight missions with up to four hours' recording time and supports a sustained data rate
of 40-50 MB/s. In order to achieve optimal performance parameters during read and write operations a proprietary file
System has been implemented. Nevertheless, transparent data access is supported by different utilities.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part Bl. Amsterdam 2000. 261
