GB1480085A - Equipment testing systems - Google Patents

Abstract

1480085 Selective signalling FERRANTI Ltd 10 Nov 1975 [9 Nov 1974] 48607/74 Heading G4H [Also in Division H4] Monitoring apparatus comprises first means to be responsive to command signals and to periodic timing signals to be operative during a first part of each timing signal period to pass a command signal state to equipment to be monitored, second means to be responsive to conditions of the equipment to produce, to the output of the first means, a return signal indicative of whether the equipment has operated in response to said command signal state passed by the first means, and third means operative during the remaining part of the timing signal period for comparing the return signal with said command signal state, the output impedance of the first means being higher during the remaining part than during the first part of the period. In Fig. 2, the periodic timing signal is applied at 28 to tristate gate 26 the output 31 of which sees low and high impedance during the first and remaining parts of each period, respectively. A "1" or "0" command is applied to gate 26 at 27 and passed during the first part via 26, 31 and 25 to one of lines 17-20 and one of lines 21-24 to select (by coordinate addressing) and control a ferrite phase shifter associated with one of a matrix array of dipole radiator elements of a phased array antenna. In Fig. 3, terminals 14, 15 are connected to the two addressing lines for the phase shifter 13. The command pulse at 14 goes via a high impedance input gate 35, and monostable 36 to an amplifier 37 the output of which has the same polarity as the command pulse at 14 (by virtue of the lower input at 47). The amplifier output saturates the ferrite at 39 in one sense or the other, a search coil 40 and comparator amplifier 41 reversing a bi-stable 44 if there is any change of state. The bi-stable output is supplied via resistor 45 and terminal 14 back to point 31 (Fig. 2) for check comparison in a gate 29 (during the "remaining part" of the timing signal period) with the command pulse at 27. More than one phase shifter may be provided per dipole. Other applications are mentioned.