Protective system
AssigneeEllsworth, Chow & Murphy, Inc.
InventorVincent Y. S. Chow
Life of this patent
Estimating the term…
Abstract
A domestic protective system which utilizes existing household AC power lines to conduct system signals between remote stations or zones and a master receiver. The system signals are established by a single carrier frequency and include a data pulse of this frequency under normal conditions, and no data pulse under malfunction conditions. Locations of zones originating system data signals are identified by time delays established prior to data transmission from each zone, this delay triggered and synchronized by data transmissions transmitted from other zones.
Claims21
A protective system having at least two remote stations and a master receiver all connected by a common AC power line, said protective system comprising:
- (a) at least one monitoring means connected to each remote station for detecting an alarm or normal condition at said monitoring means;
- (b) timing means;
- (c) signal generating means within each remote station responsive to said monitoring means and said timing means for producing and transmitting on said AC power line alarm and normal data transmission signals representing alarm or normal conditions;
- (d) each of said alarm and normal data transmission signals comprising a data pulse of greater duration than one cycle of the AC power wave form wherein said data pulse is not synced to or dependent upon said AC power wave form;
- (e) said signal generating means transmitting said data pulse after a time delay established by said timing means unique for each remote station;
- (f) transmission sensing means within said master receiver for detecting alarm or normal data transmission from each remote station;
- (g) control signal generating means within said master receiver responsive to said master signal sensing means for producing control data transmission signals;
- and
- (h) signal sensing means within each remote station responsive to data transmissions from each remote station and from said master receiver.
A method of operating a remote station in a protective system receiver all connected by a common AC power line, comprising the steps of:
- (a) monitoring resistance levels at alarm detection stations connected to each remote station;
- (b) producing a single carrier frequency signal within each remote station;
- (c) detecting a change or no change in said resistance levels, a change in resistance level indicating an alarm condition and no change in resistance level indicating a normal condition;
- and
- (d) transmitting a data pulse of duration greater than one cycle of said AC power waveform after a time delay unique for and identifying each remote station wherein said data pulse comprises said single carrier frequency under a normal condition and comprises said single carrier frequency modulated under an alarm condition.
A remote station for use in a protective system having at least two such remote stations and a master receiver all connected by a common AC power line, said remote station comprising:
- (a) at least one monitoring means for detecting an alarm or normal condition at said monitoring means;
- (b) timing means;
- (c) signal generating means responsive to said monitoring means and said timing means for producing and transmitting on said AC power line alarm and normal data transmission signals representing alarm or normal conditions;
- (d) each of said alarm and normal data transmission signals comprising a data pulse of greater duration than one cycle of the AC power wave form wherein said data pulse is not synced to or dependent upon said AC power wave form;
- (e) signal sensing means responsive to data transmissions from each remote station and from said master receiver;
- and
- (f) means to reset said timing means upon detection by said signal sensing means of data transmission signals from other remote stations.
Dependencies are inferred from the claim text.