4. Interface : In addition to the above, the demodulator/decoder 

 must properly interface with the receiver which immediately 

 precedes it and with the frame synchronizer equipment which 

 it feeds. 



VI, FRAME SYNCHRONIZER 



After the signal has been decoded and the 100-Hz clock in the decoder 

 "locked up" by the 2.5-second alternating 1-0 pattern, the decoder 

 is ready to present data to the outside world. The next segment of 

 the reply format is a 15-bit Maximal Length Sequence (MLS) pattern. 

 The 15-bit MLS is recognized by a device called a "frame synchronizer" 

 which must wait for decoder lock before looking for the 15-bit MLS, 

 At the conclusion of the MLS, the frame synchronizer must be ready 

 to present the received data in 8-bit segments to the data processing 

 equipment . 



VII. DATA PROCESSING EQUIPMENT 



It is not possible to recommend a specific system for processing the 

 received data, as this depends on the requirements of the user and on 

 how the remote sensor outputs its data to the radio set. The cost 

 of data processing system can be minimized by considering the 

 processing, if any, that is done at the platform and user's data 

 processing equipment. Obviously, the form of the data provided by 

 the sensor and the computing system must be designed together if a 

 cost effective system is to be developed. These depend on the 

 user's specific requirements and can only be defined by the user. 

 Generally, the data processing equipment must, as a minimum, 

 include the following: 



A, A proper interface to the frame synchronizer. 



B, Interpretation of the 31-bit DCP address. 



C, Parity error checking, 



D, Storage of the data. 



E, A means of retrieving the data from storage. 



VIII. OBTAINING A DIRECT READOUT RECEIVING STATION 



The above material has briefly described system parameters; readers 

 should bear in mind that NOAA/NESS cannot provide designs for 

 particular users. Anyone considering establishing his own direct 

 readout facility should contact vendors experienced in this area. 



IX. COSTS 



The following are rough estimates on costs of the various components: 



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