The yard/meter marks are counted and indicated on the 

 panel display "MEASURED LENGTH". 



A voltage proportional to the speed of the rope is also 

 derived from these marks. It is used to drive a panel 

 display of "ROPE SPEED" and to control the speed of the 

 paper chart recorder in proportion to the speed of the 

 rope. This feature requires that the rope travel at a 

 speed greater than a preset minimum and thus it is en- 

 abled by a motion sensor. 



5.1.4 Chart Recorder 



A two channel paper chart recorder is used to provide hard 

 copy of the data measured by the system. 



The LMA and LF signals are delivered to the channel sensi- 

 tivity controls and attenuated for optimum results . 



The YD/M marks and the 50/100 marks are isolated electri- 

 cally by means of a photo coupler the outputs of which 

 drive the two event marker pens . 



The speed of the chart may be controlled either by the 

 internal TIME BASE or by the speed of the rope as selected 

 by the front panel PROP DRIVE switch. 



A-46 



