Simple and Generic Tone Generator for IP Phone
Mahender Kumar, P. Chandra Sekhar, M. Nathan, Aditya Chebiyyam · 2009
need to handle Call Progress Tones (CPT) generation to provide an audible indication of the state of the call similar to the PSTN phone. Additionally, in case of systems having a keypad interface, DTMF tones need to be generated based on the key activated, either during call setup or during mid-call session. So, very low complexity generic Tone generator (TG) is required for any application, which needs to generate tones. The digital oscillator algorithm is used for generation of a single sinusoidal wave frequency. Both amplitude and frequency modulated tones are generated by different sine or cosine frequency separately mixed as per requirement of modulation scheme used. This algorithm is tested with a large number of other signaling tones (such as MF-R1, MF-R2, Caller ID Alerting Signal (CAS) etc), and the results establish that the method employed is a good compromise in terms of performance, memory requirements, and precision. Design guidelines and implementation details of generic TG are presented to further emphasize the mathematical effectiveness of the method employed.