Patent GB-402194-A (GB)
Title: Improvements in and relating to methods and apparatus for the synchronization of twoelectro-magnetic oscillations whose frequencies are unstable
IPC: H04B1/30
Filed: 1932-08-03
Abstract: 402,194. Wireless signalling ; thermionic valve currents. REGNAULD DE BELLESCIZE, H. J. J. M. DE, 47, Boulevard de la Seine, Nenilly-sur-Seine, France. Aug. 3, 1932, No. 21811. Convention date, Oct. 6, 1931. [Class 40 (v).] Two electromagnetic oscillations, either or both of which may undergo slow but relatively large changes, superposed on changes of greater rapidity but smaller amplitude, (such as those due to variations in the voltage-supply at the generator, or in temperature or to changes in the medium of propagation are synchronized by utilizing in combination two independent links, one directed to control the rapid fluctuations and the other the relatively-slow changes. The arrangement may be used for homodyne reception or for synchronizing several transmitting stations. As shown in Fig. 2, the control signal S is applied to a detector valve 1, together with a frequency H generated by a local oscillator 3. The output from the valve 1 is used to adjust the frequency of the generator 3, so that it is mantained in synchronism withwith rapid signal fluctuations, by varying the grid bias applied to that valve from the output resistance 6. The output current from the valve 1 also passes through a relay coil 22, which is balanced by a second coil 23, so that the armature 25 of the relay rests midway between two contacts 26, 27. As an initial adjustment the switch 32 is thrown on to the contact 33, which gives the grid of the valve 19 the potential of the point 31. The cumulative effect of slow frequencyvariations in the incoming control signal S then causes the armature to move to one or other of the points 26, 27 so as to close a circuit containing the resistance 28 and condenser 20 having a comparatively large time-constant, thus raising or lowering the effective grid-bias on the valve 19. This changes its internal resistance, and so alters the frequency of the generator 3 through the coil 18 until it coincides with the control signal S and is in quadrature with it. In Fig. 3 the incoming signal is heterodyned by a valve 38, and the beat-frequency output from the valve 39 is split into two branches 42 and 44. The former feeds the output valve 43, whilst the latter through an amplifier 45 excites a band-pass filter 48 which passes only sustained oscillations of carrier frequency. To synchronize slow frequency-changes, another detector valve 52 is simultaneously excited by the signal via the conductor 42, and by the local oscillations tapped off from the point 51, and operates the relay 25 in the manner previously described in connection with Fig. 2. Specifications 148,380, 187,986, 332,834, [all in Class 40 (v), Wireless signalling &c.], 355,339, 360,891, and 392,567 are referred to. The Specification as open to inspection under Sect. 91 refers to a known method of synchronization, Fig. 2 cancelled (not shown), and also describes two alternative heterodyne arrangements, Fig. 5 and 7 cancelled (not shown). This subject-matter does not appear in the Specification as accepted.