of the gear train, and drives the rubber timing belt which serves to 

 transport the styli, precisely guided by a trolley bar, across the paper. 

 The trolley also serves as the electrical connection between the print 

 amplifier and the active styli. The run pulley drives the timing gear 

 box which generates key, gate, and calibration grid timing pulses. A 

 saturated photo-optical device digitally generates extremely accurate 

 pulses . 



Paper Feed 



It is essential to advance the paper with the same precision as 

 the stylus sweep to achieve constant and accurate amplification of the 

 bottom profile at fixed ship speeds. The paper feed system (Fig 3) 

 originates at the feed roll from where the paper is fed through the 

 drive rollers, driven through a gear train coupled to the sync-drive 

 pulley, at a constant rate of 1^0 lines per inch. From the drive rollers, 

 the paper is fed past the styli and across an l8-inch long platen which 

 is the area viewed by the operator. The platen allows the operator to 

 make annotations easily on the chart. The paper then passes through the 

 pressure rollers, which keep tension on the paper and assure a smooth 

 flow, the rollers being geared directly to the drive rollers. The paper 

 is then fed to the take-up roll, where the take-up motor and clutch pro- 

 vide even tension. 



The purpose of the pressure rollers and the take-up mechanism is 

 twofold. First, if it is desired to review past charts, the chart may 

 be unwound from the take-up roll without disturbing normal paper feed, 

 due to the isolating effect of the pressure rollers. Then, after review, 

 if the rapid chart advance button is pressed, the slipping action of the 

 clutch is caneelled, and the paper is rewound at a fast rate. Second, 

 since the take-up motor has the ability to override the paper feed 

 mechanism when directly coupled, it also acts as an automatic rapid paper 

 advance. Manual advance, using the knobs on the end of the rollers, can 

 also be accomplished. 



Print Amplifier 



The print ati^jlifier (Fig h) , a key module in the PFR-193, pro- 

 vides the operator with much more closely controlled recording character- 

 istics and flexibility than has been available previously. In addition, 

 residue generated by the writing process with electrosensitive recording 

 papers has been suppressed to a new low by closely controlling the 

 energy to the stylus, resulting in an optimum power transfer. The small 

 amount of residue occurring is removed almost completely by a highly 

 efficient blower and carbon filter system. 



The input to the print amplifier is the output from the transceiver, 

 sending and receiving sonar pulses . The print amplifier processes and 



185 



