GB972809A - Testing device for visual omni-range systems - Google Patents

Abstract

972,809. Testing V.O.R. receivers. BENDIX CORPORATION. Jan. 28, 1963, No. 3486/63. Heading H4D. A standard V.O.R. receiver, comprising a receiver and detector 12, yielding the 9960 frequency modulated signal and the 30 c/s. variable phase signal, a reference signal channel comprising an F.M. detector 18, a variable phase signal channel comprising a filter 14 and phase shifter/resolver 22, and a phase detector 26, fed with the outputs of the two channels, is checked for random phase shifts by switching means 30, whereby the 30 c/s. variable phase signal is removed from the input to the variable phase signal channel and the 30 c/s. reference signal is substituted therefor. The same signal is now being applied to both inputs of the phase detector 26 and the phase shifter 22 is adjusted until the indicating means 28 connected to the output of phase detector 26 reads zero. Switching means 30, comprises, Fig. 2, a first amplifier stage, comprising a transistor 32 with a phase shifting input network 36/38 and a load resistor 48, which amplifies the reference signal and applies it to the base 54 of transitor 56 forming a second amplifier stage. The base 54 of transistor 56 is normally biased to earth via closed switch 62, cutting the second amplifier stage off. A very large resistance 61 is connected between the emitter 58 and collector 60 of transistor 56 and the variable phase signal is applied to the emitter 60 which is also connected to the input of the variable phase signal channel. With switch 62 closed the variable phase signal passes straight into its channel. When switch 62 is opened, however, transistor 56 becomes conducting, diverting the variable phase signal away from its channel input, and amplifying and applying the reference signal to the input of the variable phase signal channel. Alternatively, the switching means 30 may switch over the input to the reference signal channel.