Line-monitor circuit

• US 3,183,498 A
• Filed: 10/02/1961
• Issued: 05/11/1965
• Est. Priority Date: 10/02/1961
• Status: Expired due to Term

• Current Assignee: Anthony M. Midis, Wilfred C. Howe
• Original Assignee: Anthony M. Midis, Wilfred C. Howe
• Inventors: Midis, Anthony M., Howe, Wilfred C.
• Application Number:
  US04/142,150
• Time in Patent Office: 1,317 Days
• US Class Current: 340/644
• CPC Class Codes: H04M 3/2272 Subscriber line supervision circuits, e.g. call detection circuits

Claims

1. A MONITOR DEVICE COMPRISING A COMMUNICATION LINE FOR TRANSMITTING UNDULATING CURRENTS REPRESENTING A VOICE MESSAGE, SIGNAL MEANS FOR APPLYING A DIRECT CURRENT TO SAID LINE, AT LEAST ONE SET OF DATA TRANSMITTING PULSING CONTACTS FOR SELECTIVELY APPLYING AND REMOVING SAID DIRECT CURRENT TO OR FROM SAID LINE DEPENDING UPON WHETHER SAID CONTACTS ARE CLOSED OR OPEN, MONITOR MEANS FOR DETECTING THE DIRECT CURRENT ON SAID LINE WITHOUT AFFECTING THE UNDULATING CURRENT ON SAID LINE, SAID MONITOR MEANS COMPRISING A CURRENT SENSING CIRCUIT INDUCTIVELY COUPLED TO SAID LINE AT A POINT ON SAID LINE WHERE SAID DIRECT CURRENT APPEARS ON OR IS REMOVED FORM SAID LINE BY SAID PULSING CONTACTS, MEANS RESPONSIVE TO CURRENT FLOW OVER SAID LINE FOR EFFECTIVELY CHANGING THE IMPEDANCE OF A CIRCUIT CONTROLLED BY SAID MONITOR MEANS, AND MEANS RESPONSIVE TO SAID CHANGE OF IMPEDANCE FOR PROVIDING A SIGNAL INDICATING WHETHER SAID CONTACTS ARE OPENED OR CLOSED.