What is “On Hook Noise”?
On Hook Noise is the noise present on a telephone communications line when the phone is not in use. The MIL-4000N includes circuitry designed to eliminate on-hook noise on 48-volt wet lines. This minimizes noise input to the VOX circuitry. Line voltages over 41VDC cause the logger to reduce input sensitivity, minimizing false VOX trips when the line is on hook. An additional circuit will detect rings, start recording, and allow caller-ID to pass to the recording. This on-hook control feature is automatically disabled when the logger is connected to a dry line. Larger loggers use external line voltage mute boards.
