Patents by Inventor Carl W. Caldwell

Carl W. Caldwell has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Monitoring system for a direct-wire alarm system
    Patent number: 4283717
    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.
    Type: Grant
    Filed: October 1, 1979
    Date of Patent: August 11, 1981
    Assignee: Digital Monitoring Products
    Inventors: Carl W. Caldwell, Rick A. Britton