Tone signal detection apparatus

• US 20080158617A1
• Filed: 06/04/2007
• Published: 07/03/2008
• Est. Priority Date: 06/09/2006
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Nishi, Hirofumi
• Granted Patent: US 8,442,101 B2
• Time in Patent Office: Days
• US Class Current: 358/434
• CPC Class Codes: H04N 1/32614 related to a single-mode communication, e.g. at the transmitter or at the receiver
• CPC Class Codes: H04N 1/32641 of transmission or transmitted data, e.g. interruption or wrong number of pages
• CPC Class Codes: H04N 1/32683 Preventive counter-measures, e.g. using redundant hardware, or anticipating a fault arrangements for keeping a communication line open H04N1/32795
• CPC Class Codes: H04N 1/32791 Arrangements for reducing the handshaking procedure or protocol time
• CPC Class Codes: H04N 2201/0093 Facsimile machine H04N2201/0094 takes precedence

Abstract

A tone signal detection apparatus for detecting a tone signal of a specific frequency is disclosed. The tone signal detection apparatus includes a detecting unit, a determining unit, a time measuring unit, and a time comparing unit. A time during which a signal is not detected by the detecting unit is measured by the time measuring unit, the measured time is compared with a predetermined threshold value by the time comparing unit, and the determining unit determines that signal detection is successful if the measured time is not in excess of the predetermined threshold value.

Claims

1. A tone signal detection apparatus for detecting a tone signal of a specific frequency, comprising:

a time measuring unit for measuring time during which a tone signal is not detected;

a time comparing unit for comparing the measured time with a predetermined threshold value;

wherein the tone signal is determined to be present if the measured time is less than the threshold value.

2. The tone signal detection apparatus as claimed in claim 1, further comprising:

a tone signal detection starting/stopping unit;

a notifying unit for reporting a tone signal detection result; and

a predetermined threshold value changing unit.

3. The tone signal detection apparatus as claimed in claim 1, wherein the tone signal is an ANSam signal specified in a V.8 procedure of an ITU-T recommendation.