Abstract: A security system is provided for a mobile piece of equipment such as a freight car, aircraft, boat, automotive/truck vehicle, or other machine that may be stolen. The system consists of a central processing unit, transporting a stream of data to various components of the vehicle, and component control units attached to each of the parts of the vehicle being protected. The control units accept a code from the memory of the vehicle ignition key, alter the code, and transmit the altered code back to the CPU. The operation of certain devices that effect the operation of the vehicle and/or its protected subsystems are also disabled. These systems in turn may be linked to a central database via a system control center to control the inventory and regulation of parts both within each vehicle and between all vehicles protected by the system.

Abstract: Transient signal elimination circuitry is disposed in a local communications loop extending from a subscriber telephone to a telephone central office couples ringing and on-hook and off-hook signals through the loop after removing transients in these signals. The circuitry also isolates the telephone subscriber and central office from the local loop until an off-hook signal is detected and restores this isolation when an on-hook condition exists at the telephone subscriber. Transient signal elimination is accomplished with a CPU driven interface which detects undesirable transients such as a ringing or off-hook signal, and in response thereto generates a burst of double tone signal to alert connected equipment. In this manner, the local loop can be simultaneously used for both voice communications and a second information signal with each signal capable of occupying the same bandwidth. These signals can operate independently of each other.

Abstract: Transmission and reception of first and second information signals over a telephone local loop, simultaneous with voice communications over the same local loop, is possible if the phase and amplitude of said first and second signals are perfectly balanced. The inventive apparatus detects differences in phase and amplitude between said first and second signals, and generates digital control signals to reduce the phase and amplitude differences to zero. Adjustment of phase and amplitude is completely automatic and rapidly accomplished.

Abstract: Transient signal elimination circuitry is disposed in a local communications loop extending from a subscriber telephone to a telephone central office couples ringing and on-hook and off-hook signals through the loop after removing transients in these signals. The circuitry also isolates the telephone subscriber and central office from the local loop until and off-hook signal is detected and restores this isolation when an on-hook condition exits at the telephone subscriber. In this manner, the local loop can be simultaneously used for both voice communications and a second information signal with each signal capable of occupying the same bandwidth. These signals can operate independently of each other.