Monitoring system for a direct-wire alarm system
AssigneeDigital Monitoring Products, Inc.
InventorsCarl W. Caldwell, Rick A. Britton
Life of this patent
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Abstract
A direct-wire alarm system for scanning and monitoring a plurality of security alarm systems located in various user's facilities. The device monitors each line sequentially and converts current levels present on each line to a digital value. A digital filter is utilized to eliminate periodic line noise while a second digital filter is utilized to eliminate pulse noise. The system further comprises a line ringing system for notifying the user of a line condition and an adjustable comparator for obtaining high resolution of line current values.
Claims14
A direct-wire alarm monitoring system for high-speed sequential monitoring of a plurality of DC current loops comprising:
- (a) an analog-to-digital converter means for each loop to convert the current level to a digital value;
- (b) a digital notch filter operably connected to the analog-to-digital converter to eliminate periodic noise of a pre-determined period from each loop sequentially;
- (c) a digital comparator operably connected to the output of the notch filter to detect changes in current level;
- (d) a digital pulse filter operably connected to the output of the digital comparator to eliminate pulse noise if a change in current level is detected by the digital comparator;
- and
- (e) means for sequentially sampling the output of the analog-to-digital converter means for each loop and applying that sample sequentially to the digital notch filter.
Dependencies are inferred from the claim text.