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Chapter 5
Test and Measurement Functions
Tone Encoding
Rev. 001
CX300 ComXpert Operation Manual
22130634
5 - 46
February, 2022
5.10.3 Tone Encoding - DTMF
Dual-Tone Multi-Frequency (DTMF) is a tone composed of two sine waves of given
frequencies. DTMF is widely used for telecommunication signaling between telephone
handsets and switching centers over analog telephone lines in voice-frequency bands.
DTMF signal definition includes strict limits for timing (minimum duration and inter-digit
spacing), frequency deviations, harmonics, and amplitude relation of the two components
with respect to each other.
Table 5-26 Tone Encoding DTMF Controls and Settings
Parameter
Description
DTMF Mode
A DTMF code consists of two user 1 and 2 simultaneous
frequencies mixed together. The higher of the two frequencies
may have higher amplitude; this is referred to as a twist. If the
twist is equal to 3 dB, the higher frequency is 3 dB louder. If the
lower frequency is louder, the twist is negative.
Twist
When
Twist
is selected, one of the frequencies will have a
higher amplitude than the other.
•
Positive twist = higher frequency will be louder
•
Negative twist = lower frequency will be louder
Normal
When
Normal
is selected, both frequencies are transmitted
at the same volume.
DTMF State
State selects how DTMF pulses are sent.
Off
DMTF Encoding is OFF.
Continuous
In continuous DTMF mode, the digits/symbols in the DTMF
Sequence field are generated continuously.
DTMF State (cont)
Burst
In the burst DTMF mode, the digits/symbols in the DTMF
Sequence field are generated once each time the Start
button is pressed.
Live
When
Live
is selected, and when the DTMF Sequence field
is selected, a keypad is displayed on the UI to manually
enter tones. Each time a digit/symbol is entered into the
keypad, that digit/symbol is generated.