Gate FF. When the Gate FF is in the key state, or when the gate fimction 

 is disabled, the key pulse is fed to the amplifier circuit which gener- 

 ates the simulated contact closure with sharp rise and fall times . The 

 key amplifier output leads are isolated from ground. The maximum voltage 

 which can be applied to the key. leads' is 200 volts of either polarity, 

 and the maximum current is 0.2 amp . 



The Record Gate generates the print control signal, fed to the Print 

 Amplifier. This gate is normally controlled by the Gate FF, and disables 

 the print circuitry during the keying cycle, except during the key pulse 

 interval. Thus, the recorder will not print during the keying cycle, 

 except when a sonar pulse is generated, allowing the leading edge of the 

 key pulse from the sonar transceiver to be always printed. 



Calibration Pulse Generator 



The PFR-193 generates its own calibration marks which are printed 

 on the chart. Twenty grid marks are printed on the 100 and UOO-fathom 

 scales, and 10 on the HoOO-fathom scale. The calibration marks are 

 interrupted every five minutes by a precision switch. The possible 

 ambiguity that might result by using the same number of grid marks on 

 the 100 and UOO-fathom scales has been resolved by making the length of 

 the five minute interruptions four times longer when the lOO-fathom scale 

 is used. 



Two grid mark "timing pulses are generated by the timing pulse genera- 

 tor (Fig 8). On the l|000-fathom scale, ten evenly spaced pulses per scan 

 are used, starting at zero. When the recorder is switched to 100 or UOO 

 fathoms, the UOOO-fathom scale pulses are summed in a gate with another 

 timing pulse, which fills in the in-between pulses. The gate output 

 triggers a one-shot multivibrator, which provides a standard pulse for 

 printing. In addition, the gate is controlled by a signal from a pre- 

 cision switch, which serves as the grid interruption control, for a period 

 of 10 seconds every five minutes. 



Control Functions 



The recorder contains two precision motors and gear trains. One 

 is located in the mechanical assembly and is used to generate the sweep 

 time base. The other, the program timer (Fig 9), generates the grid 

 interrupt and deep scale time base functions. The purpose of the deep 

 scale switchover is to allow the PFR-193 to be used in applications where 

 an operator is not continually present. The recorder will automatically 

 check the base line of the UOO-fathom scale by switching to IiOOO fathoms 

 for 30 seconds. Deep scale operation will occur 1, 2, or I4 times per 

 hour. The frequency of occurrence of this event is determined by the 

 scale switch, which controls the scale clutches and scale relays. The 

 grid interruption switch and the deep scale switches are mechanically 



193 



