Improvements in or relating to electrical networks for frequency-modulated signals

摘要

823,467. Non-linear networks. PHILIPS ELECTRICAL INDUSTRIES Ltd. June 24, 1957 [June 27, 1956], No. 19811/57. Class 40 (8). [Also in Group XL (c)] A network for the transmission of frequencymodulated signals with simultaneous suppression of amplitude modulation and higher harmonics of these signals comprises a number of sections including voltage-dependent shunt resistances, preferably constituted by crystal diodes, the values of which for the highest signal amplitude constitute an increasing series from input to output so that the group transmission time is substantially constant over the entire signal frequency band. The network is an mderived low-pass Zobel filter having a value of m about 1.3 and comprises mutually-coupled series inductors. At the highest signal frequency the first resistance 7 is adjusted to a value exceeding the characteristic impedance Zo of the network and the values of the other resistances are adjusted so that each exceeds 1/3 of the value of the resistance following it, e.g. the values of the resistances 7, 8, 9 may be 1.5Zo, 3Zo and 1.5 X 2n-1Z0, where n represents the number of whole sections. The resistances may comprise parallel-connected rectifiers having asymmetric conductivity with respect to one another.