FRAC; Fracastoro; Fraccaro; Fraccaro, M. FRACDS; FRACGP; fracidin; FRACO; FRACOG; FRACP; FRACR; FRACS; fract-fract dos; Fractal; fractals; fraction; fraction collector; fraction of inspired oxygen; fractional; fractional dilation and curettage; fractional distillation; fractional excretion of sodium; fractional flow reserve; fractional injection; fractional oxyhemoglobin
In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver in the absence of a sufficiently strong desired input signal. carrier squelch is unlocked and will let any signal in. Selective calling locks out all signals except ones with the correct code. In non-critical uses, selective calling can also be used to hide the presence of interfering signals such as receiver-produced intermodulation.
Carrier Squelch (CSQ) is used when PL / CTCSS coded receive is not used. Even if any PL / CTCSS tone is present in the received signal, the receiver just ignores it and the squelch opens strictly when any received signal is strong enough to overcome the squelch level setting.