Improvements in or relating to arrangements for demodulating frequency modulated carrier wave oscillations

Abstract

Abstract 472,158. Wireless receiving systems. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE. April 21, 1937, No. 11432. Convention date, April 23, 1936. [Classes 40 (iii) and 40 (v)] Frequency modulated waves are demodulated bv feeding them to a line having distributed inductance and capacity which is so terminated as to produce reflections, and which is longer than a quarter wave at the longest wavelength to be demodulated. Fig. 1 shows the voltage distribution for four frequencies on a line of length l which is terminated by a short circuit at E. #<U> represent the changes in voltage due to changes in frequency measured by the device J, which may be placed a multiple number of quarter wavelengths from the end of the line if greater sensitivity is required. The indicator may be a current responsive device and be placed at a current anti-node. For economy in space, the line may be folded, and may have adjustable impedances such as trombone slides Ps, Fig. 4, to adjust the line for best results. The line may be shielded or be of the coaxial type, and can be matched to the indicator and input impedance, such as the antenna A, Fig. 4, by tapered sections La, L1.

Inventors

No inventors recorded.

Bibliographic Details