How do you know if squelch is off?

The indication that squelch is off is evidenced by a constant static noise. When squelch is functioning properly, it suppresses background noise when no signal is present. Therefore, if squelch is off, the audio system will continue to pass any noise, including static, which is typically present in radio frequencies.

In this context, having a constant static noise clearly signifies that the squelch is not engaging, making it the correct assessment. An SQ annunciation below the UHF mode indicates the squelch control setting but does not directly confirm its operational state.

Visual signals on a radar display and a silent audio channel do not provide relevant information regarding the status of squelch. A silent audio channel might suggest that the squelch is effectively suppressing noise, but it cannot be used to definitively identify if squelch is off.