The system provides transmission of four (4) independent input signals over fiber optic cable. Applications include alarm event triggering, building automation, environmental control systems, fire & alarm systems, gate control, traffic signal control equipment, and more. Here are the key OTN alarms and their explanations: 1. Long transmission distance, up to 20 km (11. Applicable for Door Entry Access Control System,. Free standard shipping on orders over $99 Estimated to be delivered on 12/01/2022 - 15/10/2022.