The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 17, 2006
Filed:
Jan. 14, 2005
Thomas Martin, State College, PA (US);
Thomas Martin, State College, PA (US);
Inmate Telephone, Inc., Altoona, PA (US);
Abstract
Disclosed herein is a three-way call detection system and method for detecting the addition of a third party to a pre-existing telephonic connection between a first party and a second party. The system comprises: a meter for measuring the amplitude of a line voltage of a telephonic connection between a first party and a second party, said line voltage having a frequency band F; a first filter to remove a frequency band Ffrom said line voltage and output a filtered signal, said frequency band Fbeing a subset of F; a white noise generator for generating a low level white noise signal with a frequency band that corresponds to Fand with an amplitude that is significantly below an amplitude level of the measured line voltage for frequency band F; a coupler for combining the low level white noise signal to the filtered signal, thereby outputting an additive line voltage; a second filter that passes only a portion of the additive line voltage, said signal that passes being referred to as the band-passed signal, said band-passed signal having a frequency range F, said frequency band Fbeing a subset of Fand being inclusive of F; and a processor for processing the band-passed signal and determining a baseline amplitude level associated with a two-way call. The processor monitors the band-passed signal in the time domain for a shift in baseline amplitude level, which shift is associated with the addition of a third party to the telephonic connection. The white noise being added is preferably at least 3 dB below the amplitude level of the measured line voltage, more preferably at least 10 dB, more preferably at least 20 db, and most preferably 40 db below. The frequency band Fis selected from Fto be significantly large enough to permit more reliable detection, and yet small enough to be barely perceptible to the listener. For example, Fmay comprise the frequencies from 1–2 KHz. An Fof 1–1.3 KHz. also functions well.