The ST-VOX1 Voice Operated Relay can be actuated by an unbalanced mic or line level source. It is primarily used in intercom and talkback applications where a fast contact release time (adjustable 70 to 260 ms) is desired. In applications where longer release times are desired we suggest the use of ST-ACR Series Audio Controlled…
Gating a Noisy Signal
A recent call into the RDL Tech Support line came from a contractor who was installing a paging system on a campus where it was not practical to run cable between the various buildings. They had installed a low power FM transmitter at the main office and receivers that fed the amplifiers in the various out buildings. Generally speaking, the system worked well but the end-user complained of RF interference that would cause low level noise in the local systems. The noise was such that it wasn’t noticeable during a page, but was more than irritating when no program was present. We suggested that an RDL ST-GLA1 Gated Line Amplifier be installed between each FM receiver and local amplifier.
The ST-GLA1 is designed for use in a variety of applications where it is necessary to automatically mute audio when no valid signal (only low level noise) is present. The module offers automatic gating to the input of conventional mixers or amplifiers when the expense of adding an automatic mixer to the signal chain cannot be rationalized.
The ST-GLA1 is equipped with multi-turn trimmers for precision adjustment of level and threshold. Two LEDs simplify the adjustment process: one indicates correct audio gain setting and the second lights when the module is gated ON. All audio switching is solid-state and uses a soft-switch transition that sounds instantaneous without any clicks, pops or harsh transitions. Muting occurs two seconds after audio drops below the preset threshold level. This delay time can be extended with the installation of an external capacitor.
The contractor installed an ST-GLA1 in each of the local systems and reported back to us that their customer is very satisfied with the results.