Clark and Yarnall 



WWVB 



CALIBRATION 



RECEIVER 



WWVB 



CALIBRATION 



RECEIVER 



PRECISION 



OSCILLATOR 



A 



PHASE COHERENT 

 DEMODULATOR 



STEP ADJUSTABLE 

 NARROW BAND FILTER 

 (AVAILABLE BANDWIDTHS 

 FROM 0.01 TO 10.24 HZ) 



PHASE COMPARATOR 



DISPLAY 



ie(t) R(t)l 



PRECISION 



OSCILLATOR 



B 



PHASE COHERENT 

 ' DEMODULATOR I 



FILTER 



I 



COMPARATOR 



(T) Transmitted signal is of form: AcoswoL 



d) Received signal is of form: R(t)cos [cuot - 9(t)] , 

 where R(t) and 6(t) are functions of time- 

 varying processes in the medium. 



Fig. 3 - Fxonctional elements of acoustic measurement system 



341 



