Patent
1976-02-13
1977-04-19
Claffy, Kathleen H.
H04M 150
Patent
active
040189961
ABSTRACT:
An improved system and method for protecting communications systems using in-band signaling from malfunction which may produce serious circuit failures such as false operation of the disconnect circuit.
Typical practice of the invention involves detection of those main signal sounds that are similar to and imitate the in-band control tones and using the detected sounds to control a switching circuit which inserts a band reject filter into the system so as to reduce the amplitude of such sounds before they are fed to the communication system utilizing in-band signaling.
Under normal conditions such sounds are not present or are of insufficient amplitude or are present for too short a time period to cause false operation. Accordingly, the band reject filter is not normally active and there is no degradation of frequency response. Even during those periods when the filter must be inserted in the line to provide protection, the bandwidth of the filter is narrow so that disturbance of the frequency response is minimized.
REFERENCES:
patent: 2971062 (1961-02-01), Salihi
patent: 3306984 (1967-02-01), Leonard
patent: 3349191 (1967-10-01), Mann
patent: 3394226 (1968-07-01), Andrews
Claffy Kathleen H.
Popek Joseph A.
LandOfFree
Communication network protection system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Communication network protection system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Communication network protection system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-104698