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Concerning the SCSI Il interface, the camera can work as hard disk or as processor device and will be controlled by a
software tool which has the task to change the camera status via commands.
If there is no command within 5s after switching on the camera, the preceding. control parameters are activated by the camera.
The camera can be controlled by VAX, SUN, IBM or MAC. The WAAC- camera software can change the SCSI modes via
commands.
WAAC Structure
LIISEBM. roa FEE. 0 ae ____ Digital Unit __
Baffle ; r pro 4 —— TRIGGER IN
vi TRIGGER OUT
Window Fibers | |
| | | SCSI wide SCSI II >
| i. «
Data | |
| Aquisition | | DSP2
‘ System ; |
| |
| ; | uM |
| pas — DCE | » PCI- PC
Optics | Hive: | | | |
| Thermal | | ; | r |
| Control | |
| | Te | [bL ose |
| Power Converter | Power 27V |
CLC - CCD Line Controller DSP - Digital Sigaal Processor MUX - Multiplexer
DAS - DATA Aquisition System FPM - Focal Plate Module
DCE - Data Compression Electronic FEE - Front End Electronic
Fig.: 1. : Structure of the WAAC camera
The performances of the camera is based on the camera structure in Fig.: 1.. The photons issue electrons and holes in the 3
CCD sensors. The 3 CCD sensors convert the charges in to voltages and change the impedances. In the next step the FEE
receive the signal via the CCD preamplifier. The front end electronic contain the data acquisition system which is controlled by
the CCD line controller. The CCD line controller includes the digital interface to the digital signal processor and generates all
clocks for the CCDs. Through the interface of the CCD line controller the DSPI has the capability to program the FEE
parameters. This interface has also the task for real time control of the dark signal. Via this interface the DSPI receive the
digitized 11 Bit raw data. These raw data are written in the DCE memory via the DSPI. The data are synchronized in the DCE-
FIFO.
The DSPII controls the generation of data formats at the DCE. The user has the possibility to select the data formats of the 11
Bit raw data or 8 Bit normalized data or JPEG data via commands. After the DCE data handling the DSPII controls the SCSI Il
interface. The data are transmitted via the wide SCSI Il bus to the PC. The DSP Il has also the task of the command
interpretation, camera status control, and trigger control.
The WAAC- camera can be triggered from external devices. The camera has four trigger inputs which realize the
synchronisation of the measurements. One input has to be driven as a 50ohm input and the others are differential TTL inputs.
The WAAC- camera can be triggered on the CCD- line begin, HSYNC, VSYNC, integration time, cycle time, central pixel and
other triggers which are included in the camera software. The camera has also four trigger outputs. One output is designed as
50ohm output and the others are differential TTL outputs.
The camera has also the capability for trigger combination, trigger sequences and boolean functions of trigger values.
4. SOFTWARE CONCEPT OF THE WAAC CAMERA
For the software concept is it very important to realize an environment which supports all aspects on the flexible camera
concept. The software kernel is a real time software package which solve all problems of multiprocessing and task handling.
The interfaces to the software kernel are simple assembler programs. The tasks of this assembler programs can be splited in
two parts: the first part has to realize the interface to the C- library and the second is the realization of the hardware driver.
The real time kernel software was developed with a virtual signal processor model. Kernel services and data are automatically
routed through the network and exploit multiple parallel communication paths. The micro kernel provides for full primitive
scheduling between the tasks according to their current priority (5). In the case of the WAAC- camera structure the DSPI is
connected with the DSPII and the software has to decide which process is necessary for the next multitasking part for the
optimal timing condition.
The shell structure of the real time software has some advantages for the user software developments. The environment of the
software has the possibility to test the new software parts in the PC. After the test the software can be transmitted and tested
in the WAAC- camera. The kernel contains also software parts for the elimination of false handling and gives an error report
after the measurement. In the first part of the software the DSPs make self tests of all boards and software tools. The result
of these tests can be received via the SCSI Il and the command for the generation of the result file can be build at the
IAPRS, Vol.30, Part 5W1, ISPRS Intercommission Workshop "From Pixels to Sequences", Zurich, March 22-24 1995
