C. AUTOTAPE 



1. GENERAL 



The Aeris II Autotape survey equipment was designed by the Cubic 

 Corp. as an outgrowth of its high -precision, electrotape, distance -measuring 

 equipment. The Autotape system is capable of automatic distance measuring 

 for both fixed and mobile situations. It uses omnidirectional or directional an- 

 tenna in determining distance from a mobile platform to two fixed responder 

 positions on a known base line. Range information accurate to 1 meter + 10 ppm 

 times the measured range over ranges of 100 meters to 100 kilometers (62 miles) 

 is numerically displayed for visual monitoring by the operator. A voice com- 

 munication mode of operation between the Interrogator and each transponder is 

 used when initiating operations. A data output connection for external recording 

 or processing of range information is available with a BCD output suitable for 

 data processing. An Autotape plotter may be used at the Interrogator for a con- 

 tinuous plot of a moving platform in x-y coordinates. 



DESCRIPTION 



The Autotape system consists of a mobile interrogation unit and two 

 remote transponders located at either end of a fixed base line. (See Figure 

 VI-2.) In automatic operation a built-in program at the Interrogator controls 

 the Autotape Responders, measures the range to each Responder, and sequen- 

 tially presents each range on an integral digital display. 



Separate carrier frequencies in the 10-cm (2900 - 3100 mc) band are 

 used for the Interrogator and each Responder. A precisely regulated crystal os- 

 cillator located at the Interrogator serves as a basic clock controlling all fre- 

 quencies . Responder transmissions are separated by frequency multiplexing 

 techniques which require only one antenna and one transmitter at the two-range 

 Interrogator which serves both Responders. This assures that both ranges are 

 measured from a single focal point at the Interrogator and allows both ranges to 

 be measured and displayed within 50 microseconds. 



Distances are measured using electronic phase comiparison techniques . 

 Three basic modulation frequencies are automatically sequenced, and a phase 

 comparison is made between transmitted and received frequencies at the Inter- 

 rogator. By a unique use of modulation frequencies, the Responder electronic 

 time delays are cancelled. The Autotape system then automatically measures 

 the rf propagation time, utilizes a preset average value for the index of refrac- 

 tion to correct the velocity of propagation, and displays the resulting range to 



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