GB641344A - Improvements in or relating to devices for generating electrical oscillations - Google Patents

Abstract

641,344. Valve generating circuits. MERLES, A. J. Aug. 20, 1945, No. 21242. [A Specification was laid open to inspection under Sect. 91 of the Acts, May 30, 1946.] [Class 40 (vi)] In an oscillation generator providing a number of discrete frequencies by mixing two frequencies from each of two basic series, the following ratios are of the same order and not smaller than 0.04: (a) frequency spacing to the mean frequency in each series ; (b) mean frequency in the lower to the mean frequency in the upper series; (c) twice the lowest frequency in the lower series to the highest frequency in the upper series. A crystal-controlled oscillator 02 generating 100 kc/s. controls a second generator 01 generating 10 kc/s., harmonics of each generator being produced and fed to filter 03, 04. By depressing suitable switches C3, C4 frequencies from each series are fed to a mixer M1, tile sum frequency only being passed by the highpass filter F selected by the appropriate switch CF which may be ganged to the corresponding switch C4. The difference frequencies may also be utilized, Fig. 2 (not shown), thus reducing the number of filters 04 required. The harmonic generator 1 may take the form shown in Fig. 3, suitable harmonics from the 100 kc/s. oscillator 02 being selected by filters 06 and applied together with a fixed harmonic selected by filter 05 to the mixer M2, the output being fed to the filters 04. In a modification, Fig. 5 (not shown), both low-pass and high-pass output fillers are employed, and in a further modification, Fig. 6 (not shown), using a third basic generator of 1 kc/s. the output frequency is determined to I kc/s.