d. 3. 
ying 
= 163 = 
d) Immediate opto-electronical signal generation permits direct data 
transmission by telemetry, without requiring a complex intermediate 
process, and thus leads to a practically unlimited mission duration. 
Furthermore, it permits direct digital storage and processing of 
data in the computer. 
e) A certain problem is caused by the differences in sensitivity in- 
herent in the individual sensor elements. Thanks to an automatic 
calibration and real-time correction process, all radiometric diffe- 
rences are corrected during image scanning, covering the entire 
transmission way from the lens to the digitized signal. 
This working principle is suitable for radiometry ranging from the 
visible to the thermal infrared spectral range. In the present case, 
the measuring range of the EOS extends from 0,45 p up tofu (Fig. 3), 
the use of filters permitting selection of the spectral channels desired. 
The geometric resolution is determined by the distance between the centers 
of the individual sensor cells, which is referred to as "pixel resolution". 
The most recently developed sensors feature, for the visible and near in- 
frared range, respective values of 13 p and 16 p. The customary indica- 
tion in line pairs/mm is obtained by multiplying this pixel resolution 
by the factor 2} 2 =3. This leads to a resolution capacity of approx. 
27 Lp/mm, a value which matches in every respect the value obtained by 
means of aerial photographs. Figure 4 illustrates, in the example of the 
CCD 131 type Fairchild sensor, the square wave response curves measured 
of several spectral channels. 
Structure of the Experimental Electro-optical Scanner 
The photo-camera system comprises the following components: 
a) Opto-electronic camera (scanner), Fig. 5 
b) Control and electronic module, Fig. 6 
c) Oscilloscope for signal observation 
d) Magnetic tape unit 
Fig. 7 indicates the set-up with the individual assemblies. The entire 
functional sequence is controlled by a microprocessor, the scanning para-