| 摘要 |
<p>In a digital messaging system (10), an apparatus (37) and method for determining whether a DTMF (Dual Tone Multi Frequency) digit is present on an input signal (11, 12). A heuristics engine (37) performs a series of tests on the input signal (11, 12) using a set of parameters that are stored in a RAM (38). There is one parameter for each of a set of input signal (11, 12) characteristics and for each of a set of operating modes of the digital messaging system (10). All of the parameters are configurable. The configurability allows for the use of non-standard telephone equipment (13, 14) and minimizes deleterious effects such as talkoff. The tests are from the set of sets comprising an absolute magnitude test, a frequency deviation test, a twist test, an echo test, a consistency test, and a temporal test.</p> |
