SECONDS 

 5 6 7 



10 



1 r 



I"" I I 



llill 



FIGURE VI -4 HI-FIX TIME -SHARING OF MASTER AND 



SLAVE TRANSMISSIONS 



b. Receiver Unit 



The receiver is used as a position -fixing instrument aboard the navi- 

 gating vessel in the hyperbolic system, which places the master and the two 

 slave stations ashore . In the ranging mode the master station and receiver are 

 placed aboard the navigating vessel and each slave station is located at the end 

 of a base line ashore . The slave station receiver is required to hold the phase 

 of the slave transmission at a constant and predetermined relationship with re- 

 spect to the master . 



With the navigator's receiver in the operate mode, the incoming 

 1900 kc (approximately) signal from the master and the two slave stations is 

 converted to an intermediate frequency of 132 kc . In addition to the phase - 

 sensitive cw transmissions, the trigger signals from the master station are 

 also received . These pulses are extracted from the intermediate frequency 

 output to activate circuitry which gates the two digital display circuits . Using 

 master timing pulses in this manner allows the digital display for each channel 

 to be activated only during the proper slave transmission, as illustrated in 

 Figure VI -4. 



164 



atthur Zn.llittlc.2lnr. 



