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The most common set of supported tones is a set of 39 tones including all tones with Motorola PL codes, except for the tones 8Z, 9Z, and 0Z (zero-Z). [6] The lowest series has adjacent tones that are roughly in the harmonic ratio of 2 0.05 to 1 (≈1.035265), while the other two series have adjacent tones roughly in the ratio of 10 0.015 to 1 ...
Dual-tone multi-frequency signaling (DTMF) is a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. [1]
Tone burst is an obsolete method of selective calling where the radio transmits a single 0.5- to 1.5-second audio tone at the beginning of each transmission. This scheme existed before circuitry for CTCSS had been developed.
Voltage vs. time of sine waves at reference and line levels, with V RMS, V PK, and V PP marked for the +4dBu line level. A line level describes a line's nominal signal level as a ratio, expressed in decibels, against a standard reference voltage. The nominal level and the reference voltage against which it is expressed depend on the line level ...
In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver in the absence of a strong input signal. [1] Essentially, squelch is a specialized type of noise gate designed to suppress weak signals.
Multifrequency signaling is a technological precursor of dual-tone multi-frequency signaling (DTMF, Touch-Tone), which uses the same fundamental principle, but was used primarily for signaling address information and control signals from a user's telephone to the wire-center's Class-5 switch. DTMF uses a total of eight frequencies.
Tones used for remote controls are described in ratios called decibels: for example, the second tone of a sequence might be 10% of the level of the first tone. The highest level tones are set to the maximum allowable for the DS-1 channel or telephone line. The figure at right shows the envelope of a function tone's two-tone sequence.
Dial tone is a continuous tone of the addition of the frequencies 350 and 440 Hz at a level of −13 dBm. Audible ringing tone is defined as comprising frequencies of 440 and 480 Hz at a level of −19 dBm and a cadence of 2 seconds ON and 4 seconds OFF. Low tone, also busy tone, is defined as having frequency components of 480 and 620 Hz at a ...