GB677177A - Improvements in or relating to a tele-autograph or follow-up system - Google Patents

Abstract

677,177. Frequency discrimination. CONSOLIDATED ELECTRIC CO. March 14, 1950 [March 16, 1949], No. 6357/50. Class 37. [Also in Group XXXVIII] The invention relates to a follow-up system, more particularly a writing telegraph, in which the frequency of an oscillation is varied in accordance with the position of the stylus, and consists in employing at the receiver the frequency discriminating circuit of Fig. 2. The received frequency is applied to valve 53 whose outis applied to transformer 63 which has two secondary windings 65, 66. The winding 66 supplies out-of-phase signals to diodes 72, 73 which are both fed with a signal over condenser 83 from the junction of condenser 46 and inductance 47 in series across the secondary 65. If the condenser 46 and inductance 47 are tuned to the incoming frequency, the signal fed over condenser 83 is 90 degrees out-of-phase with both the signals on the diodes from secondary 66 and the output from the diodes on conductor 81 is zero. If the incoming signal departs from the frequency to which 46, 47 is tuned, the signals applied over 83 vary in phase accordingly to provide an output at 81 of appropriate magnitude and sign.