62 



HYDROGRAPHIC MANUAL 



(j) Any radical change of the zero check 

 is an indication of trouble in the system. 

 A loose antenna connector will cause such 

 a change. Consult a technician to see if 

 other factors are causing the change. 



(k) If practicable, observe an occasional 

 three-point fix for comparison with a cor- 

 rected Shoran fix. This may disclose un- 

 suspected errors. 



(1) Adjust the receiver gain as necessary 

 to retain the shape of the ground station 

 signal. 



(m) Great care should be taken to pre- 

 vent any damage to the coaxial cables, both 

 ashore and afloat. If these cables are crimped, 

 bent sharply, or the insulation broken, water 

 will enter the cable. This moisture can ruin 

 the cable, rendering the Shoran useless, and 

 this particular type of equipment failure is 

 difficult to find. 



3-48 Raydist control systems. — Raydist 

 is a radio system in which phases of two 

 continuous-wave signals are compared. A 

 number of designs of the Raydist system 



permits presentation of position data in 

 various forms: range, elliptical, and hyper- 

 bolic or combinations of two of them. The 

 range or circular system is used by the Coast 

 and Geodetic Survey. In this system the 

 distance to the Ri station is measured dir- 

 rectly, however the line-of-position from the 

 Ro station is elliptical and is converted 

 mechanically to a range distance and pre- 

 sented in this form. 



Instructions for servicing and operating 

 Raydist equipment are contained in man- 

 uals furnished by the manufacturer and 

 are supplemented by additional instruc- 

 tions and diagrams compiled in the Elec- 

 tronics Laboratory. 



The use of Raydist for control of hydrog- 

 raphy has been limited to one major project 

 at the time this is written. The following 

 instructions are based on this experience 

 and are subject to change with further 

 developments. 



3-49 Raydist operating principles. — The 



determination of distance by the Raydist 



Figure 15. — D. M. Raydist equipment for mobile station. 



