are confined to specified bands and the kind of radar (and its character- 

 istics) carried by a particular vessel can frequently be determined from 

 official or semiofficial records, such as those maintained by the USCG 

 for U.S. flag vessels or those maintained by Lloyds of London on a world- 

 wide basis. 



The foregoing circumstances raise the possibility of 

 detecting and/or classifying foreign fishing vessels by intercepting 

 and analyzing their radio or radar emissions. Two techniques are po- 

 tentially applicable. One, based on direction finding, provides a means 

 for determining the position of detected targets. The second involves 

 the classification of a detected target on the basis of information de- 

 rived from intercept of its radio transmissions. Both techniques can 

 be combined in a single system. 



The techniques can be enhanced by the use of radio or 

 radar beacons. Moreover, the ultimate in technical simplicity and 

 reliability in the use of these techniques would be a permit system for 

 foreign fishing vessles that required mandatory, periodic communication 

 to the USCG of location, status, and intentions. The political or admin- 

 istrative acceptability of such an approach and consideration of its 

 susceptibility to evasion or deception are matters beyond the scope of 

 this survey. 



The technology for both the vessel radio and radar equip- 

 ment and equipment for direction finding and communications interception 

 and analysis is highly developed and numbers of systems have been developed 

 both for military and civilian use. Direction finders and intercept/ 

 analysis equipment can be operated on shore or from floating, airborne, 

 or spacebome platforms. 



The propagation range of radio and radar signals depends 

 largely on the radio frequency. In general, radio frequencies above 



79 



