Inaudible tone generator

• US 3,209,086 A
• Filed: 06/11/1962
• Issued: 09/28/1965
• Est. Priority Date: 06/11/1962
• Status: Expired due to Term

• Current Assignee: Richard P. Boylan
• Original Assignee: Richard P. Boylan
• Inventors: Boylan, Richard P.
• Application Number:
  US04/201,356
• Time in Patent Office: 1,205 Days
• US Class Current: 379/30
• CPC Class Codes: H03B 5/1203 the amplifier being a single transistor
• CPC Class Codes: H03B 5/1231 the amplifier comprising one or more bipolar transistors
• CPC Class Codes: H03B 5/1256 the means comprising a variable inductance
• CPC Class Codes: H03B 5/1296 the feedback circuit comprising a transformer
• CPC Class Codes: H04M 3/26 with means for applying test signals or for measuring

Claims

1. PORATABLE APPARATUS FOR TESTING A TELEPHONE LINE HAVING A PREDETERMINED RATE IMPEDANCE AT THE AUDIO FREQUENCIES NORMALLY USED FOR VOICE COMMUNICATION, WITHOUT INTERFERING WITH SUCH NORMAL AUDIO FREQUENCY USE THEREOF, SAID APPARATUS COMPRISING:

A PORTABLE SOURCE OF DIRECT CURRENT;

A PAIR OF CONNECTION POINTS ADAPTED TO BE COUPLED WITH SAID LINE UNDER TEST;

FIRST TRANSISTORIZED MEANS POWERED BY SAID SOURCE FOR GENERATING A CARRIER SIGNAL OF ANINAUDIBLE FREQUENCY SUBSTANTIALLY GREATER THAN SAID AUDIO FREQUENCIES NORMALLY USED FOR VOICE COMMUNCATION;

SECOND TRANSISTORIZED MEANS POWERED BY SAID SOURCE AND COUPLED WITH SAID FIRST MEANS FOR MODULATING SAID CARRIER SIGNAL WITH AN AUDIO FREQUENCY MODULATING SIGNAL;

ELECTRICAL MEANS INCLUDING CIRCUIT MEANS FOR EXTENDING THE FREQUENCY RESPONSE OF SAID LINE UNDER TEST TO INCLUDE THE FREQUENCY OF SAID CARRIER SIGNAL AND FOR MAINTAINING THE IMPEDANCE OF SAID LINE AT SAID RATED VALUE WHEN THE LINE IS COUPLED WITH SAID CONNECTION POINTS, SAID ELECTRICAL MEANS FURTHER INCLUDIGN A HIGHPASS FILTER COUPLED WITH SAID CIRCUIT MEANS FOR ATTENUATING NOISE ON SAID LINE WHEN THE LATTER IS COUPLED WITH SAID CONNECTION POINTS;

IMPEDANCE MATCHING MEANS COUPLING THE OUTPUT OF SAID SECOND TRANSISTORIZED MEANS WITH SAID ELECTRICAL MEANS;

AND COUPLING MEANS INTERCONNECTING SAID ELECTRICAL MEANS WITH SAID CONNECTION POINTS.