62 OCEAX ELECTRONIC XAVIGATIOXAL AIDS 



///. Operational Requirements — 



Designed for operation by bridge personnel with little or no technical train- 

 ing in scope interpretation. The operation of this equipment must not cause 

 interference to or be affected by other navigational and electronic equipment 

 normally carried aboard ship. 

 IV. Performance — 

 Range: 



Maximum — 30 miles. 

 Minimum — 400 yards. 

 Resolution: 



A properly designed Radar with pulse length and antenna beam widths 

 as elsewhere prescribed herein should give a range resolution of 200 

 yards and bearing resolution of 6° on the shortest sweep scale. 

 v. Indication and Data Output — 

 Indicator: 



At least 7 inches PPI (plan position indicator) scope. 



Sweep linearity shall not deviate more than ±3 percent except that 

 the first and last 10 percent of the sweep may deviate by ±7 percent. 

 Range scales: 



Variable 2-5 miles; 4-15 miles; 15-30 miles; positive range scale in- 

 dication is to be provided. 

 Range indication: 



Fixed electronic range markers; accuracy of ±2 percent or ±100 yards, 

 whichever is greater; not more than five range circles appearing on 

 the scope. 

 Bearing indication: 



True or relative bearing indication with bearing cursor; over-all ab- 

 solute bearing accuracy from antenna to display ±30. 

 Positive means should be provided to indicate whether or not the over-all 

 operation of the radar is such that it may be relied on to provide effective 

 anticollision and navigational information. 



VI. Antenna — 



Truncated parabola or equivalent. 

 Beam Width: 



Horizontal — 5° maximum to half power points. 



Vertical — 15° minimum (7.5° either side of horizontal) to the one-half 

 power points. 

 Mounting: 



Navy standard flange 16 ^^ inch bolting circle with eight I'^ie inch holes 

 equally spaced, two opposite holes on center line. 

 Polarization: 



Horizontal or vertical. 

 Rotation: 



Continuous, 360° in azimuth, speed of rotation 6 to 15 revolutions per 

 minute; control on main on-off switch. 



Antenna reversing switch, may be provided to sector scan. 

 Sidelobes: 



20 decibels down. 



VII. Transmitter — 



IP, RP, and video band pass — Optimum for pulse length chosen. 



Frequency recommended — 3000 to 3246 or 9320 to 9500 megacycles. 



Radio frequency source — Magnetron. 



Modulator — Hydrogenthyratron, hard or soft tube, or equivalent. 



Main transmission line — the over-all attenuation from the radio fre- 

 quency source to the radiator must not be more than 1 ^2 decibels one 

 way on the 10-centimeter band nor more than 3 decibels one way on the 

 3-centimeter band. 



Peak power — 15 kilowatts on 3-centimeter band and 7 kilowatts on 10 

 centimeter with the above transmission line attenuation limits. 



Pulse repetition rate — minimum of 800 pulses per second. 



Pulse length — 1 microsecond maximum. 



Trigger — Positive 10 to 50 volts (across high impedance) . 



VIII. Receiver — 



Over-all gain — 120 decibels. 



Video output — 2.5 volts ±0.5 volt (across 75 ohms). 



