nce 
ing 
DR 
to 
SS. 
  
4. FUTURE PROSPECT 
  
The present article addresses the idea of real-time or near-real-time 
access to Sar Imagery. It is suggested how the ESTEC Real-Time Processor 
Breadboard could be used in the ERS-1 ground segment to experiment this 
jdea. However, to obtain full benefit from real-time Sar Processor, 
adequate links for the dissemination of the Radar Images to the users must 
be provided. Links via Data Relay Satellites are being investigated by the 
European Space Agency. As a contribution, ESTEC has proposed as part of 
the experiment of Electronic Document Delivery by Satellite, named APOLLO 
(Reference 3), an experiment of remote access to ERS-1 Sar Images. In the 
experiment, ERS-1 Sar raw data would be transmitted to ESTEC via the APOLLO 
link and processed on-line by the Real-Time Processor Breadboard. The 
experiment intends to use efficient coding methods of the Sar Images 
(compression), currently developed by ESTEC (Reference 4), for image 
retransmission and storage. 
REFERENCES 
(1) "The ESA/BMFT Real-Time Sar Processing and Test Facility", R.W. Okkes, 
ESTEC, Noordwijk, The Netherlands. ISPRS Commission II Meeting, Tokyo 
9-10 Nov. 1983. 
(2) "The Ground Segment for a European Ocean Monitoring Satellite ERS-1", 
M. Jones. Int. J. Remote Sensing, 1983, Vol. 4, No. 3, pp. 683-694. 
(3) "APOLLO System Requirements Specification". ESA SP-1068, EUR 9413 EN, 
1984. 
(4) "Rate Distortion Functions of Sar Imagery", R.W. Okkes, ESTEC, 
Noordwijk, The Netherlands.  ISPRS Commission II Meeting, Baltimore 
26-30 May 1986. 
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