Method and apparatus for increasing the response sensitivity and the interference resistance in an alarm system
First Claim
1. A method for operating a danger alarm system for increasing the response sensitivity and the interference resistance of the alarm system, said alarm system having a plurality of alarm units connected via a plurality of alarm lines to a central station, each of said alarm units continuously emitting measured values representing conditions monitored by said alarm units, said measured values being cyclically sampled at said central station, said method comprising for each alarm unit the steps of:
- forming an alarm quiescent value from each sampled measured value emitted by an alarm unit;
subtracting a quiescent value formed from a measured value sampled immediately preceding a current measured value from said current measured value;
forming a current comparison value from the difference resulting from said subtraction;
storing said current comparison value;
comparing said current comparison value with a rated limiting value;
activating a display means for displaying an alarm if said current comparison value is greater than or equal to said rated limiting value; and
updating a quiescent value memory by replacing said quiescent value formed from said measured value sampled immediately preceding said current measured value with a quiescent value formed from said current measured value if said current comparison value is less than said rated limiting value.
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Accused Products
Abstract
A method and apparatus for increasing the response sensitivity and the interference resistance in an alarm system such as a fire alarm system which cyclically samples a plurality of alarm units in the system for obtaining a series of measured values from each alarm unit, the measured values being utilized to form a quiescent value which is stored in a quiescent value memory. With each sampling cycle a current comparison value is formed from the alarm measured value, the stored quiescent value, and a comparison value from a previous sampling cycle stored in a comparison value memory. The current comparison value is then written in the comparison value memory as the new comparison value. The current comparison value is compared with a rated limiting value, and if the comparison value is greater than or equal to the rated limiting value, a display unit is activated indicating an alarm. If the comparison value is less than the rated limiting value, a new quiescent value is formed from the measured value and the stored quiescent value and written into the quiescent value memory.
73 Citations
9 Claims
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1. A method for operating a danger alarm system for increasing the response sensitivity and the interference resistance of the alarm system, said alarm system having a plurality of alarm units connected via a plurality of alarm lines to a central station, each of said alarm units continuously emitting measured values representing conditions monitored by said alarm units, said measured values being cyclically sampled at said central station, said method comprising for each alarm unit the steps of:
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forming an alarm quiescent value from each sampled measured value emitted by an alarm unit; subtracting a quiescent value formed from a measured value sampled immediately preceding a current measured value from said current measured value; forming a current comparison value from the difference resulting from said subtraction; storing said current comparison value; comparing said current comparison value with a rated limiting value; activating a display means for displaying an alarm if said current comparison value is greater than or equal to said rated limiting value; and updating a quiescent value memory by replacing said quiescent value formed from said measured value sampled immediately preceding said current measured value with a quiescent value formed from said current measured value if said current comparison value is less than said rated limiting value. - View Dependent Claims (2, 3, 4)
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5. In a danger alarm system having a plurality of alarm units connected to a central station by a plurality of alarm lines, each alarm unit continuously emitting measured values corresponding to the conditions monitored by said alarm units and a means at said central station for cyclically sampling said measured values, the improvement of a means for increasing the response sensitivity and the interference resistance of said alarm system, said means being located at said central station and comprising:
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a quiescent value former connected to an alarm line for an alarm unit for forming a quiescent value from each sampled measured value emitted by said alarm unit; a quiescent value memory connected to said quiescent value former for storing said quiescent values therein; a comparison value former connected to said alarm line for said alarm unit and to said quiescent value memory for forming a current comparison value from a current measured value and a quiescent value formed from a measured value sampled immediately preceding said current measured value; a comparison value memory connected to said comparison value former for storing said comparison values therein; a comparator device connected to said comparison value memory and to said quiescent value former, said comparator device comparing said current comparison value with a rated limiting value; and a display means connected to said comparator device, said comparator means activating said display means for displaying an alarm signal if said current comparison value is greater than or equal to said rated limiting value, and said comparator device enabling transfer of a quiescent value from said quiescent value former which was formed from said current measured value to said quiescent value memory for updating said quiescent value memory if said current comparison value is less than said rated limiting value. - View Dependent Claims (6, 7, 8, 9)
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Specification