Patent GB-509139-A (GB)
Title: Improvements in or relating to electric transmission and/or control systems
IPC: G05D3/12
Filed: 1937-10-05
Abstract: 509,139. Electric control and signalling systems; valve relays. SPERRY GYROSCOPE CO., Inc. Oct. 5, 1937, No. 26941. Convention date, Oct. 7, 1936. Addition to 500,468. [Class 40 (i)] [Also in Group XL] In an electric system for transmitting data or controlling apparatus of the type described in the parent Specification wherein transmission is effected over a two-wire line by the variation of phase of a voltage relatively to a timing voltage, the timing voltage is applied to the line at the transmitter instead of at the receiver ; moreover, the transmission may be effected by radio instead of by line wires. Figs. 2A, 2B show transmitting and receiving apparatus respectively of a system wherein two separate controls may be effected over a pair of line wires 3<1> by transmitters 10, 10<1>. Each transmitter comprises a single phase coil 44, 45 rotatable in a polyphase field 42, 43 supplied from a motor-generator set 28 comprising a plurality of 3-phase generators 40, 41 and a single-phase timing voltage generator 39 of different frequencies. Additional generators and corresponding transmitters may be provided if desired. The coils 44, 45 are connected in series with the generator 39 on the line wires, the phase of the voltage of generator 39 being fixed and of the coils variable in accordance with their positions. The received voltage is passed through an amplifier 7 and separate frequency components are filtered at 8, the fixed phase voltage passing into circuit 9 for driving a motor-generator 12 in synchronism with the generator at the transmitting station. The variable phase voltages are passed into circuits 17, 18 and by means of phase detectors 59, 59<1> are compared with voltages of similar frequency derived from the generator 12. When phase equality exists between the voltages in circuits 18, 19, the valve circuit comprising the phase detectors 59, 59<1>, modulators 66, 661 and gaseous rectifiers 76, 76<1> is balanced, but when the balance is disturbed, one of the field windings of motor 23 predominates and the motor is driven to operate the controlled objects 27, 83 until a rotatable coil 85 adjusts the phase relationship in circuit 19 into the balanced condition. In the modified arrangement associated with the circuit 17, phase variation produces deflection of the instrument pointer 89 in one or other direction, zeroization being effected by manual adjustment of the associated rotatable coil 90. Thermionic valve circuits. The plates of the phase detectors 59, 59<1> are supplied with singlephase voltage and an in-phase relationship from the coil 85 and signal voltage in 180 degrees out-of-phase relation and normally the voltages are 90 degrees out of phase and produce equal and opposite voltage drops across resistors 61, 61<1> and no net drop across the points 62, 62<1> of the low-pass filter 63. When, however, the phase of the signal voltage is varied, the D.C. voltage developed across the points 62, 62<1> together with an A.C. bias voltage from the transformer 68 is applied to the control grids of valves 66, 66<1> arranged in push-pull to produce a net A.C. in a transformer 67 which supplies amplifiers 70 and rectifiers 76 for controlling the motor 23. The Specification as open to inspection under Sect. 91 states that the variable phase signals may be transmitted over power mains and in consequence the timing voltage generator may be dispensed with, the polyphase generators at the transmitter and receiver being driven synchronously from the mains. This subjectmatter does not appear in the Specification as accepted.