• If USCG units were transponder-equipped, they 

 could be vectored to disabled transponder- 

 equipped vessels for rescue purposes. 



The WARF has demonstrated the detection of ships including 

 fishing trawlers at over-the-horizon distances using skywave HF radar. 

 The detection of smaller vessels would most likely not be feasible 

 with a skywave radar, but it would be possible with a surface-wave 

 radar. Reference 8, the report of a study by SRI of surveillance re- 

 quirements at PMTC that are similar in many respects to those associated 

 with enforcement of the 200-nmi fishing zone, gives further information 

 on the projected capabilities and costs of practical OTHR. Volume Two 

 of this OTA survey report gives examples of the kind of performance that 

 could be expected from OTHR used for fishery zone enforcement. While 

 it is not intended to imply that OTHR will uniquely provide full coastal 

 coverage out to 200 nmi, it is suggested that OTHR has good potential 

 to support enforcement of the 200-nmi fishery zone. 



3. Microwave Radiometry Technique 



a. Description 



Microwave radiometry is a completely passive detection 

 technique that uses the microwave energy emitted and reflected by a 

 surface as opposed to active techniques such as radar, which transmit 

 a signal and then measure the backscattered signal. A microwave radiom- 

 eter has no range-measuring capability and provides only a measurement 

 of microwave brightness temperature as a function of look direction. 

 The radiometer is simply a sensitive detector or receiver of microwaves 

 in a selected band of frequencies. The microwave energy received by 

 the radiometer from a particular direction consists of energy emitted 

 from the sea surface and from the intervening atmosphere, and energy 

 reflected by the sea surface. Detection of a ship is possible because 

 the microwave brightness temperature of a ship is different than that 



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