OCEAN ELECTRONIC NAVIGATIONAL AIDS 



37 



Figure 3 



PPI scope, showing echoes obtained from reflector-equipped buoys. 



bands by approximately 10 to 175 megacycles. Most of the merchants ship 

 Radars in iise may receive the Ramark frequency by the addition of a modi- 

 fication to the Radar. To facilitate this tuning, the later-type commercial 

 Radar models are equipped with a single switch which automatically sets the 

 Radar receiver to the Ramark frequency. This is usually accomplished by 

 allowing the switch to cut in a separate local oscillator in the Radar receiver, 

 tuned to the proper Ramark frequency. The latest Coast Guard type 

 TRSC-1 Radar is equipped for Ramark reception. 



RAMARK 



It appears that the Ramark is the Radar beacon form which offers the most 

 promise for peacetime use. Therefore, in the Coast Guard, active develop- 

 mental work has been pursued for some time on Ramarks for both the X- 

 and S-bands. The ultimate goal of the Ramark program is to provide stable, 

 reliable, and relatively inexpensive equipment suitable for long periods of 

 unattended operation at important landmarks where they will serve for posi- 

 tive identification of established navigation reference points. 



In its present form, the equipment required for a Ramark installation is 

 quite simple, consisting of a low-power source of radiofrequency energy and 

 a keying device, simple antenna, and power supply. A complete beacon trans- 

 mitter is contained in one cabinet. It is desirable that the Ramark equipment 

 be compact, highly rugged and reliable, of low-power drain, capable of 



