GB402316A - Improvements in or relating to high frequency transmitting systems - Google Patents

Abstract

402,316. Wireless transmitting systems ; piezo-electric crystals. LORENZ AKT.-GES., C.,1, Lorenzweg, Tempelhof, Berlin. April 3, 1933, Nos. 9948, 9949, and 9950. Convention dates, April 5, 1932, and March 18, 1933. [Class 40 (v).] In a system for synchronizing a number of separate transmitters S1 from a central control station Z, as for instance in common-wave broadcasting, a basic frequency of say 2,000 cycles is fed to each transmitter S1 through individual channels A comprising a frequencychanger F separated by a piezo-electric or magnetostrictive oscillator G of very low attenuation from a second frequency-changer N, and a filter St. To prevent undesirable coupling between the input and output circuits of the piezo-electric crystal Q in the unit Q, the electrodes E1, E2 are separated as far as possible as shown in Fig. 2, or are disposed at rightangles to each other. The crystal oscillations may be maintained by the back-coupling coils L1, L2, independently of the feedline A, or by an additional pair of electrodes as shown in dotted lines. Frequency-stability may also be ensured by occasional control from the central station, by switching-in a phase-meter P, Fig. 1, which, if an out-of-phase condition exists, closes a circuit and operates a motor M to adjust a tuning-circuit of the local transmitter S1. The line A is thereby set free for other work during non-control intervals. Specification 342,732 is referred to.