records. If the wave record spectrum analyzers mentioned above could 
be modified so that they will give reliable results, then instead 
of months per analysis it would require only five or ten minutes to 
analyze a twenty minute record. It is therefore advisable to analyze 
a number of records such as the one treated above numerically and 
then to compare the results with the electronic analysis in order 
to calibrate the analysis. 
Design features of wave record analyzers 
The design features of an electronic analyzer will be described 
in general in order to show what is needed in such an instrument. 
Plans are being made to modify the instrument devised by Klebba 
[1946], and a Kay Electric Company sonograph is being studied in 
order to convert it to a wave analyzer. The above instruments will 
be modified and interpreted in the light of these considerations. 
Wave analyzers should have the following features as suggested 
by the numerical analysis given above. 
1) The length of the record to be analyzed should be of the order 
of 20 to 35 minutes. Provision for the analysis of variable length 
records over a range of from 10 to 45 minutes would be advisable but 
not essential. 
2) The band pass filter should be square shouldered and it should 
have a Ap proportional to the same value employed in the numerical 
analysis above. Too wide a band pass would result in poor resolution 
of swell spectra and too narrow a band pass would result in an ex- 
tremely erratic analysis. The shape of the filter is very important 
and the typical tuned circuit response curve is not very good for 
this application (see Tukey and Hamming [1949] for further details). 
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