by the local oscillator, into true frequencies appropriate to the true 



recording time. Analyses will, in general, be made for the 0- to 250-cps 



scale or 0- to 2500-cps scale. If the 0- to 2500-cps scale is used, 



the oscillator frequencies are multiplied by 10 to give analysis 



frequencies . 



The frequency multiplication factor (S) is that number by which 



the true frequencies (f^) in the record have been multiplied, during 



data preparation and analysis, to yield the analysis frequencies (f^), 



f^ = ^ [1] 



t S 



The frequency multiplication factor (S) is determined by the 

 recording tape speed (s ), and the playback tape speed (s-) by 

 the equation 



S=iPli> xi£^> [2] 



where (1) and (2) in Equation [2] refer to first or second record and/or 



playback. From Equations tl] and [2] , the true frequencies are found 



to be 



s^(l) s^(2) 



^ = ^a s^(l) s^(2) ^^'^ 



P P 



If, for example, a signal is recorded at 1-7/8 ips, played back at 30 ips, 

 re-recorded at 3-3/4 ips, and played into the analyzer at 15 ips, then 

 Equation [3] states that the analyzer frequencies must be divided by 

 64 to get the true frequencies. 



It is sometimes desirable to display the abscissa scale in terms 

 of the circular frequency of encounter ( cUg)- This is given by 



19 



