US3821479A — Noninterfering electrical signaling

Claim 1

Independent Claim 158 words

An electrical signaling system comprising a plurality of monitor stations for transmitting signals in response to the status of a selected condition, a supervisory central station, at least one transmission path interconnecting said monitor stations and said supervisory central station, said supervisory central station including a plurality of receiving devices connected to said transmission path for receiving the signals transmitted by said monitor stations, said receiving device having an output to indicate the status of the selected condition and at least one input circuit associated with each receiving device and connected to the output of the receiving device, said input circuit having a clocked flipflop connected to said output to store the status of the selected condition, and an EXCLUSIVE OR gate having as inputs, the flipflop and the output of the receiving device, the EXCLUSIVE OR gate having an output signal connected to a scanning circuit to indicate a change in the status of the selected condition.

Claim 2

Dependent Claim 158 words

An electrical signaling system comprising a plurality of monitor stations for transmitting signals in response to the status of a selected condition, a supervisory central station, at least one transmission path interconnecting said monitor stations and said supervisory central station, said supervisory central station including a plurality of receiving devices connected to said transmission path for receiving the signals transmitted by said monitor stations, said receiving device having an output to indicate the status of the selected condition and at least one input circuit associated with each receiving device and connected to the output of the receiving device, said input circuit having a clocked flipflop connected to said output to store the status of the selected condition, and an EXCLUSIVE OR gate having as inputs, the flipflop and the output of the receiving device, the EXCLUSIVE OR gate having an output signal connected to a scanning circuit to indicate a change in the status of the selected condition.

Claim 3

Dependent Claim 50 words

The electrical signaling system of claim 1 in which said scanning circuit includes at least one selector circuit having inputs to receive the output signal from the EXCLUSIVE OR gate, and at least one demultiplexer circuit to feed back a delayed version of the output signal to clock the flipflop.

Claim 4

Dependent Claim 37 words

The electrical signaling system of claim 2 including means for sequentially scanning the inputs of the selector circuit and means for inhibiting sequential scanning when the output signal indicates a change in the status of the condition.

Claim 5

Dependent Claim 33 words

The electrical signaling system of claim 3 including a printer and a programmer circuit for causing the printer to print a message corresponding to the condition at which the sequential scanner was inhibited.

Claim 6

Dependent Claim 126 words

A multiplex electrical signaling system comprising a plurality of monitor stations, a supervisory central station, at least one transmission path including two conducting paths interconnecting said monitor stations and said supervisory central station, each conducting path having first and second ends, each conducting path looping out from the supervisory central station and returning back to the central station, said central supervisory station including a current sensitive relay coil connected to one end of each of said pair of conductive paths, the other ends of said conductive paths being connected to a source of power, said relay coil having associated with it contacts, the contacts being arranged to supply power to both ends of the conductive path at the supervisory central station when the coil is deenergized.

Claim 7

Dependent Claim 126 words

A multiplex electrical signaling system comprising a plurality of monitor stations, a supervisory central station, at least one transmission path including two conducting paths interconnecting said monitor stations and said supervisory central station, each conducting path having first and second ends, each conducting path looping out from the supervisory central station and returning back to the central station, said central supervisory station including a current sensitive relay coil connected to one end of each of said pair of conductive paths, the other ends of said conductive paths being connected to a source of power, said relay coil having associated with it contacts, the contacts being arranged to supply power to both ends of the conductive path at the supervisory central station when the coil is deenergized.

Claim 8

Dependent Claim 44 words

The multiplex electrical signaling system of claim 5 including a circuit means to disconnect said relay from the power source when the coil is deenergized and a switch to momentarily supply energizing current to the relay coil whereby the relay coil will be reset.

Claim 9

Dependent Claim 111 words

The multiplex electrical signaling system of claim 6 further including short circuit control means connected across the transmission path to detect a decrease in the impedance between the two conductors, said means including a transistor having an emitter, base, and collector, the collector being connected to one side of the source of power through a current sensitive device, the emitter being connected to a second side of the source of power through a predetermined voltage drop, and a resistor between the emitter and base, the base being connected to the transmission path whereby a voltage is produced between the base and emitter in proportion to the current between the two conductors.

Claim 10

Dependent Claim 16 words

The multiplex electrical signaling system of claim 7 wherein the current sensitive device is a relay.

Claim 11

Dependent Claim 69 words

The multiplex electrical signaling system of claim 6 wherein the source of power is isolated from earth ground, and further including an earth ground control for indicating when there is a short between earth grouNd and the transmission path, said earth ground control including a relay coil having one terminal connected to earth ground and the other terminal connected through impedances to both sides of the source of power.

Claim 12

Dependent Claim 71 words

An electrical signaling system comprising a plurality of monitor stations, a central supervisory station, at least one transmission path including two conducting paths interconnecting said monitor stations and said central supervisory station, said monitor stations including a transmitter time discriminator for providing an indicating signal of short time duration when a momentary actuating device is operated, and an indicating signal of long duration when an extended time actuating device is operated.

Claim 13

Dependent Claim 71 words

An electrical signaling system comprising a plurality of monitor stations, a central supervisory station, at least one transmission path including two conducting paths interconnecting said monitor stations and said central supervisory station, said monitor stations including a transmitter time discriminator for providing an indicating signal of short time duration when a momentary actuating device is operated, and an indicating signal of long duration when an extended time actuating device is operated.

Claim 14

Dependent Claim 45 words

The electrical signaling system of claim 10 wherein said monitor station includes a single tone transmitter, said transmitter being turned off when the extended time actuating device is operated, and being turned off for a predetermined short time after actuation of the momentary actuating device.

Claim 15

Dependent Claim 180 words

The electrical signaling system of claim 11 wherein the transmitter time discriminator includes a first transistor, the transmitter being connected to a collector of the first transistor and the extended time actuating device being connected to an emitter of the first transistor, the first transistor being normally turned on when the extended time actuating device and the momentary actuating device are closed. a second transistor, first circuit means to connect a collector of the second transistor to the base of the first transistor, the momentary actuating device being in a base circuit of the second transistor, a timing capacitor resistively connected to the base of the second transistor, the momentary contact being connected across the capacitor in the base circuit of the second transistor so that the capacitor charges to turn on the second transistor, when the momentary switch is opened, whereby the capacitor discharges partially through the second transistor when the momentary actuating device is closed and the first transistor is held for a short time while the second transistor is on and the momentary actuating device is closed.

Claim 16

Dependent Claim 37 words

The electrical signaling system of claim 12 including a receiver time discriminator for distinguishing two signals from the transmitter time discriminator and for producing two signals which indicate the status of the devices at the monitor station.

Claim 17

Dependent Claim 49 words

The electrical signaling system of claim 13 wherein said receiver time discriminator includes a delay device having a delay time corresponding to the minimum time actuation of the extended time contact, said delay device being connected to receive a delayed version of the signal output of the data receiver.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1977-06-27	1977-12-27	1978-06-28	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1981-06-27	1981-12-27	1982-06-28	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1985-06-27	1985-12-27	1986-06-28	$7700.00	Window Closed / Lapsed

Noninterfering electrical signaling

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