Abstract: A controller, either a microprocessor or finite state machine, is used to generate a pulse train whose frequency and duty cycle can be varied to alter the frequency and amplitude of the output of a driven audio transducer. The ability to control both frequency and amplitude allows programmatic synthesis of many audio effects such as steady tones, warbles, beeps, sirens and chimes with no hardware or circuit changes. The transducer can be a piezoelectric bender or a speaker. The output of the controller controls a switch that builds current in an inductor when the switch is on. When the switch is turned off, the energy stored in the inductor is dumped into the audio transducer, either directly or through intermediate capacitor storage. This allows the generation of voltages across the transducer many times the supply voltage.

Abstract: System and method for automatically broadcasting voice-based prompt warnings toward an embarkation and/or disembarkation location at which passengers such as students and others may or will be present. The method is multi-model providing voice messages during an approach mode, a stop mode and a standby mode. Recorded human voice messages are employed for the prompt and are the recorded voices of one or more people having voice characteristics generally recognizable by the passengers to an extent effective to supplement the function of the immature prefrontal cortex.

Abstract: Embodiments of the invention provide a high degree of security to a computer or several computers connected to the Internet or a LAN. Where there is a high degree of confidentiality required, a combination of hardware and software secures data and provides some isolation from the outside network. An exemplary hardware system consists of a processor module, a redundant non-volatile memory system, such as dual disk drives, and multiple communications interfaces. This security system must be unlocked by a passphrase to access data, and all data is transparently encrypted, stored, archived and available for encrypted backup. A system for maintaining secure communications, file transfer and document signing with PKI, and a system for intrusion monitoring and system integrity checks are provided, logged and selectively alarmed in a tamper-proof, time-certain manner. The encryption keys can be automatically sent encrypted to be escrowed with a secure party to allow recovery.