Improvements introduced in procedures and apparatus for discriminating, through filters, radio frequency signals or signal impulses received in pulse navigation systems. (Machine-translation by Google Translate, not legally binding)

摘要

Improvements introduced in procedures and apparatuses for discriminating by means of filters the radiofrequency signals or signal impulses recited in pulse navigation systems, such as loran c systems and the like, being characterized the improvements of the procedure because they consist of receiving said signals; filtering the signals with an amplitude response characteristic as a function of the frequency of the substantially rectangular stepped function type having a relatively high and substantially constant amplitude response in a "predetermined frequency band containing the center frequency of the signals, while the frequencies located immediately beyond the sides of said band are abruptly rejected and the frequencies higher and lower at a relatively high predetermined attenuation level are attenuated in a substantially constant manner, and in filtering in addition the signals thus filtered with a response characteristic substantially in the form of a bell of maximum amplitude at said central frequency somewhat higher than the constant high amplitude, and in progressively rejecting in a substantially symmetric way the upper and lower frequencies, and finally with an attenuation greater than said attenuation cons relatively high default rate of the filter characteristic of the stepped function type, said bell-shaped response characteristic having points whose attenuation is similar to that of the filter characteristic of the stepped function type within the limits of said frequency band predetermined and passing the points of intersection of the bell-shaped characteristic through and below said predetermined level of relatively high attenuation of said stepped function characteristic, so that the direct and delayed signal pulses are discrepant, while rejecting frequencies from other sources adjacent to said predetermined band of frequencies and equally frequencies very far from sources located in the vicinity. (Machine-translation by Google Translate, not legally binding)