R1 and R2 tone generation. 12. The GENF module shall generate tones with one to three unique cadence pairs (on/off pairs). A.4.2 Performance Requirements 1. Frequency accuracy shall exceed 1 Hz. 2. Level accuracy shall exceed 0.5 dB. 3. Timing information shall exceed 1 ms accuracy. A.5 Universal Tone Detector A.5.l Overview The Universal Tone Detector (UTD) is a high configurable tone detector. By changing parameters, this algorithm can classify a wide range of single and dual tone call progress signals generated in a wide variety of countries. A.5.2 General Since different tones need different detection heuristics, and tones may have multiple specifications, each tone is tagged with a tone category identifier. Software License D2 Technologies, Inc. and Maintenance Agreement August 4, 1997 CONFIDENTIAL 27 ----------------------------------------------- Tone Category Call Progress Signal ----------------------------------------------- 1 Modem 2 FAX CNG 3 Audible Ringback 4 Busy 5 Reorder or Congestion 6 Number Unobtainable 7 SIT 8 Dial tone 9 Unknown Tone ----------------------------------------------- Table A-3: Tone Categories In addition to specifying a tone category, the parameters include a value that is returned to the application when the tone is detected. This parameter need not be unique. This allows multiple specifications to report the same tone event to the application. UTD is table driven. Using this approach, the tone detector searches parameter tables for a matching tone. When a tone matches, the tone code determines the heuristics necessary to completely classify the tone. Also, the tones must be specified in a way that a set of parameters corresponds to either a single tone, a dual tone, or an amplitude modulated tone. --------------------------------- Code Tone Type --------------------------------- 0 Single Tone 1 Dual Tone 2 Modulated Tone --------------------------------- Table A-4: Call Progress Tone Types A.5.3 General Functional Requirements UTD functionally combines a single tone detector and a dual/modulated