DYNAMIC RING VALIDATION USING CYCLICAL PATTERN RECOGNITION
Original Publication Date: 1990-Aug-31
Included in the Prior Art Database: 2004-Apr-05
Xerox Disclosure Journal
The use of embedded modems for Remote Interactive Communications (RIC), enables electroreprographic machines to interactively communicate with an external host system. A dificulty in implementation of the RIC system is the lack of a standard set of ring characteristics across international PBX systems. For example, the Bell standard ring, illustrated in Figure la, utilizes a 2 second ring pulse, denoted by the active-low Ring Detect pulse, and a 4 second interim or dead period between active ring pulses. This standard ring cycle poses little problem for a modem to detect and answer. However, certain 'European' style ring systems, utilize an alternative ring sequence, comprising a series of two, or optionally three, ring pulses for each ring cycle. This alternative ring sequence is illustrated in Figure lb. In the two pulse case, the first ring pulse is present for a time period XI, after which no pulse is present for a period Y 1. Following the dead period, a second ring pulse is received for time X2, again followed by a dead period Y2. Optionally, this sequence may be repeated for a third time as illustrated by X3. The ring cycle is then completed by a longer interim period where no ring signal is sent.