234 



BELL SYSTEM TECHNICAL JOURNAL 



CALCULATED 



MEASURED 



50 



40 



25 u 

 a. 



20 



10 



- 5 



0.1 



ANTI-RESONANCE 



Fig. 15.5 — Typical characteristic of a quartz crystal measured by the Performance Index 



meter. 



Solving these equations simultaneously, it is found that 



1 1 



u = 



Ci = 



Co(c02 — COi) 2ciJeCo(c02 — COi) 



^"0(^2 — cci) 2Co(a)2 — ooi) 



(15.50) 



15.70 Experimental Data 

 The performance of the P.I. meter may best be illustrated by experi- 

 mental data. The following data indicate the correlation which may be 

 obtained between the P.I. meter and various types of oscillator circuits. 

 Experimental considerations are extended to 



(1) Frequency and ampUtude correlation with a "Pierce" and "Tuned- 

 Plate" oscillator 



