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software command tool. All test information is written in the HKD information which will be stored in default spaces of the 
science data files. 
The other part of the software is running on the PC if the camera is measuring. This part has the task of the quick. look 
visualisation and the house keeping data control. After the measurement the software can verify the image sequences in off line 
software parts and control the HKDs or give an off line visualisation. 
5. AUTO CONTROL CONCEPT 
The auto control concept is based on the scientific requirements on the WAAC- camera. For the radiometric resolution of 8 Bit 
it is necessary to control the dark signal and pattern noise of the CCD and the objective. This is the reason for the analog 
correction of the Photo Response Non Uniformity (PRNU) and the Dark Signal Non Uniformity (DSNU) (2). : 
The camera concept has also the possibility of compression control. The compression can be influenced by the quality factor 
for JPEG algorithm (4). For the controlling of the compression the DSPII has to know the observing parameter. One aspect is 
the data rate of the camera and the other the quality of the images. Both aspects can be controlled inside of the barriers of 
the JPEG algorithm. 
The bidirectional support of the SCSI Il interface is the main important condition for the connection with the WAAC camera. 
Over this interface the camera receives external information, commands, and control parameters for the on- line data 
processing. 
The auto control of the trigger in- and outputs is a important facilities for the combination of the camera with other 
instruments or measurement devices. Via the SCSI Il interface the camera can receives auxiliary information which are 
generated by other devices. The advantage of the camera trigger condition is the possibility of definition of the external trigger 
and the combination of the received input trigger with the output trigger of the camera. This capability of the camera is 
important for the complex imaging facility. 
6. NEW HIGH SPEED INTERFACE PERFORMANCE 
There are several options for data channels which do not restrict the data transfer. The best solution for this problem could 
be the application of SDH/SONET- fibre channel standard or the differential wide SCSI Il interface. We decided to take the 
differential wide SCSI Il interface. The performances of this interface depends on the PC- controller board and on the hard 
disks. That was one reason for an in house PCI controller design. 
As memories work two hard disks of 2x 2GByte with a peak data rate of 7MWords/s. The configuration WAAC- camera with 
PC, HD and SCSI interface has the average performances of 2MWords/s. 
If the WAAC- camera works as a processor device, it has the possibility to work without the PC. In this case the camera can 
drive RAID arrays devices. This arrays have a capacity of 245GBytes and a maximal data rate of 20MWords/s. The camera can 
drive 7 RAID array memories. It could be necessary for long flights. If the camera works as stand alone device, then the 
camera has not the opportunity for the visualisation. 
7. SPECIFICATION SHEET 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
WAOSS WAAC 
Focal Length, f 21,7 mm 21,7 mm 
FOV (Across the Track) ET <80Ÿ 
Optics Spitmo- Russar-96 Spitmo- Russar-96 
Number of CCD- Lines 3 3 
Spacing of CCD’s 10,1 mm 10,1 mm 
Convergence Angle 250 250 
IFOV (Quadratic) 3,23 x 107^ rad 3.23 x 10^ rad 
Elements per CCD- Line 5184 5184 
Elements Spacing 7 m 7 m 
According to Orbit Data Hn = 250 km H = 5 km (v = 200 km/h) 
Swath Width (Nadir CCD) 420 km 8,4 km 
Min Ground Resolution 
- in Line Direction 80 m 16 m 
- in Trajectory Direction 80 m 16m 
Radiometric Resolution 8 Bit 8 Bit 
Spectral Channels 
- Nadir 470...670 nm 580...770 nm 
- Forward,Backward 580...770 nm 470...670 nm 
Data Compression Factor 2...20 2...20 
Data Compression Method DCT- JPEG DCT- JPEG 
Computer Performances 20 MIPS 20 MIPS 
Output Science Data rate 100...500KBit / s 100KBit / s...24MBit / s 
Physical Dimensions L:373 x B:190 x H:218 mm L:285 x B:190 x H:202 mm 
Mass 8 kg 44 k 
Power 18 W 15W 
  
  
IAPRS, Vol.30, Part 5W1, ISPRS Intercommission Workshop "From Pixels to Sequences", Zurich, March 22-24 1995 
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