Rca1948FrequencyModu.. - The New Jersey Antique Radio Club

430 FREQUENCY MODULATION, Volume Iby (6). The Bessel amplitude coefficients J n (m f) of the side frequenciesare as follows: 6Jo (25) =J 1 (25) =J 2 (25) =J 3 (25) =J t (25) =J ā (25) =J e (25) =J 7 (25) =/ 8 (25) =/ 9 (25) =/ 10 (25) =Ai(25) =/ 12 (25) =Jib (25) =Ju(25) =Ju (25) =J 16 (25) =At (25) =J 18 (25) =J 19 (25) =/20 (25) =0.0963-0.1254-0.10630.10830.1323-0.0660-0.1587-0.01020.15300.1081-0.0752-0.1682-0.07290.09830.17510.0978-0.0577-0.1717-0.1758-0.08140.0520J 2i (25)^22 (25)^28 (25)J 24 (25)/ 2B (25)^26 (25)J 2i (25)/ 28 (25)^20 (25)^80 (25)^si (25)/ 32 (25)^33 (25)^34 (25)^85 (25)/ 36 (25)^37 (25)^38 (25)^39 (25)/w (25)/«(25): 0.1646: 0.2246: 0.2306: 0.1998= 0.1529: 0.1061:0.06778: 0.04028:0.02245: 0.01181:0.005889: 0.002795: 0.001267: 0.000550: 0.000229:0.000092: 0.000036: 0.000013: 0.000005: 0.000002:0.000001The amplitudes of the side frequencies are certainly negligible beyondthe 35th side frequency for any practical application. Therefore, theinterval 2rr X 0.965 X 10 6 g «i g 2ir X 1.035 X 10 6 contains all the nonnegligibleside frequencies.B. Measure or calculate the steady-state complex-network characteristic/(»).Example: The amplification—frequency and phase-shift—frequencycharacteristics of a network can be measured. The real part of f{u>)isthen obtained by multiplying the amplification by the cosine of thephase-shift angle. The imaginary part of /(») is obtained by multiplyingthe amplification by the sine of the phase-shift angle.For several networks, however, it is practical to calculate the networkcharacteristic from its circuit. Figure 3 is the simplifiedschematic of a tuned amplifier, for whichX L = — X = jX at a> (28)6Eugene Jahnke and Fritz Emde, "TABLE OF FUNCTIONS WITHFORMULAE AND CURVES," Dover Publications, New York, N. Y., 1943,p. 179.