These are the instruments whose data can be {ed to the tape recorder, 
A compression factor of 4 reduces the data rate from the OCM £o 700 kbits/s. 
We have examined various combinations of instruments sending data to 
the tape recorder. For example, with all these instruments switched on, 
a 5 Gbit tape recorder would be full after 24.7 minutes, but data compression 
would increase this to 63.5 minutes, 40 that 2.6 times as much data can be 
stoned and played back. If only the OCM by itself were switched on, coverage 
£8 obviously improved by a factor of 4. 
6 CONCLUSTONS 
Data compression presents a way of greatly increasing the coverage 
area for the case where data is being recorded and played back to a ground 
station. The penalty wich ispaid is a degree of error in the digital imagery. 
However, these emons ane considenably smaller than the system errors and 
the uncertainty in user algorithms. 
7 ACKNOWLEDGEMENTS 
This work was supported by the European Space Agency under contract 
n° 4835/81 /NL/HP (SC). 
Thanks are also due to M. J-C Degavre of ESTEC and to DR S M Singh 
of Dundee Unviensity for their help and encouragement. 
REFERENCES 
1 Charlton J A, 1979, Proc Remote Sensing 
Society Conference, Dundee. 
2 McEvoy N A, 1981 Proc Remote Sensing 
Society Conference, London. 
3 Rice R F, 1975, SPIE Seminar Proceedings on Efficient Transmission 
of Pictorial Information. 
  
  
  
  
   
  
  
  
  
  
   
  
  
  
   
  
  
  
  
  
  
    
  
  
  
   
  
  
  
  
  
  
  
  
   
  
  
   
  
  
    
  
   
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