What test verifies the proper operation of the squelch function?

The operational function test is designed specifically to assess the performance of various components and features of a communication system, including the squelch function. The squelch function is critical in filtering out background noise and only allowing signals above a certain threshold to be heard, thus providing clearer communication.

During an operational function test, the technician can evaluate whether the squelch is properly muting the audio when no signal is present and allowing audio to pass through when a usable signal is received. This ensures that the communication system operates correctly in real-world scenarios, where it needs to distinguish between noise and actual signals.

The other options, while relevant to different aspects of communications testing, do not focus specifically on the squelch function. Signal strength tests measure the power of incoming signals but do not evaluate the muting capabilities of the squelch. Noise floor analysis assesses the general level of background noise in a system, without directly checking the squelch functionality. An interference check looks for unwanted signals or noise that could affect communication but doesn't directly test whether the squelch is functioning properly.