The transmitter operates at a frequency of 1 .85 mc and produces 

 precisely spaced pulses at a peak power of 10 kw (average power about 25 watts). 

 The pulse width is about 60 seconds and is produced with a repetition rate of 

 41-2/3 pulses per second. The peak power can be raised to 18 kw when ranges 

 greater than 500 miles are required . The transmitter output is fed to a 

 quarter-wave flat-top antenna. 



b. Ground Station Equipment 



The ground station equipment receives rf pulses from the ship and 

 transmits a signal back to the ship after a definite time delay. All ground sta- 

 tion equipment used for this purpose is similar in operation to the shipboard 

 equipment except for the controller indicator. 



The indicator contains a precision 100-kc oscillator which controls 

 the timing functions of the shore station. It is closely synchronized to the ship 

 crystal by appropriate AFC and synchronizer equipment and maintains a mini- 

 mum timing accuracy of 0. 1 microsecond . The degree of synchronization is 

 continuously displayed for the operator. 



A cathode-ray tube with horizontal sweeps is used to display the 

 shipboard and ground station signal pulses . The operator continuously adjusts 

 the shore station signal to match the time of arrival of the shipboard pulse . 



A quarter -wave vertical radiator is used for both transmitting and 

 receiving. A ground plane consisting of radial wires approximately 100 feet 

 long is required for proper antenna operation. 



The equipment requires about 5 kw of 115v, 60 cps, single-phase, 

 alternating current , This is sufficient for both equipment and station operation . 



3. ACCURACY 



Both systematic and random errors occur in the operation of EPI 

 equipment . 



a. Systematic Errors 



Systematic errors include such factors as: 



113 



artbur ai.lCittlcJnr. 



