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The following table defines the tones used in DTMF (see ANSI T1.401-1988 Section 7.2):
Each tone is composed of a low-high pair of frequencies as defined in the table:
|DTMF Char||Low (Hz)||high (Hz)|
DTMF Tone Power is given by the following table:
|Max. Power per tone||+1.0|
|Min. Power per Low freq. tone||-10.5|
|Min. power per High freq. tone||-8.5|
Notes: frequency limit is +- 1.5%, difference in power between the low and high frequencies should not exceed 3dB and the power of the high frequency tone should equal or exceed the low frequency tone.
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