| 摘要 |
493,846. Distributing music &c. GUIDED RADIO CORPORATION. April 14, 1937, No. 10636. Convention date, May 28, 1936. [Class 40 (iv)] In a system for distributing announcements &c. on ships, the signal currents are fed to the loudspeakers over two independent networks, preferably constituted by the neutral wires of the normal and emergency power wiring circuits with earth return, to which the signal source and loudspeakers are coupled through transformers, the object being to minimize failures due to undesired grounds and short-circuits and interruptions of the circuits. In Fig. 1, the two networks comprise neutral wires 7-9 and 16-18 branching respectively from the main neutral wires 6, 15, which are connected together through a switch 20 and an impedance 21 acting as a choke as regards the signal currents. The signal currents are applied to the networks through condensers 27, 28 from the output transformers 24, 25 of an amplifier 23, the secondaries being grounded at one end to the hull of the ship. Each loudspeaker 34 is fed through transformers 29, 30, the primaries being connected at one end through condensers 32, 33 to a wire of each network and at the other end to ground. The signal currents may be fed to the networks in opposition with respect to ground, the primaries of the transformers 29, 30 being in opposition. This arrangement has the advantage of reducing noise effects. Fig. 3 shows an arrangement for automatically short-circuiting the relevant output transformer 124, 125 in the event of a break in one of the feeders near the amplifier. The feeders are shunted by relays 128, 129 in series with a condenser 127, so that the appropriate relay operates due to the building up of potential, locks over a second winding and short-circuits the corresponding transformer. Fig. 5 shows a system for distributing modulated carrier signals, the loudspeakers 221 being fed through rectifiers 220, and at some stations through tuned circuits 219, so that those stations receive signals only when the appropriate carrier frequencies are transmitted. The Specification as open to inspection under Sect. 91 describes also modified systems in which the loudspeakers are coupled to the networks through condensers. This subjectmatter does not appear in the Specification as accepted. |
