A D/A converter has a serial interface. Of the sets of the data representing multiple control signals output from latch circuits, the data representing input data, the data representing strobe signal, and the data representing clock signal are supplied to the D/A converter. A mask circuit is provided in the path supplying the strobe signal. When a parity detection circuit detects a transmission error, the mask circuit masks the strobe signal to be supplied to the D/A converter, thereby preventing the D/A converter from outputting an analog output signal corresponding to the input data.

An interface error monitor system for monitoring data exchanged between a controller and a data converter over an interface includes a multi-stage linear feedback shifter register associated with the data converter for generating a pseudo random number sequence; a signature generating circuit responsive to data exchanged between the controller and data converter for altering the pseudo random number sequence generated by the linear feedback shifter register to create a signature of the data.

A method and system of measuring availability of an in-flight entertainment system ("IFE") on an aircraft. The method comprises designating a subsystem weight factor to each subsystem of said IFE, with the sum of all subsystem weight factors being equal to a predetermined number, selecting at least one element of the subsystem to measure its availability, designating a zonal weight factor for the at least one element based on a predetermined class to be serviced by the at least one element, assigning an element loss factor based on a level of service for at least one element, collecting performance information regarding the at least one element during a predetermined period of time, and measure the element's availability based on the subsystem weight factor, the zonal weight factor, the element loss factor and the level of service.

A printer assembly and a method for determining the position of a printer component, such as a printer paper-feed roller, during a move of the printer component from an initial position toward a desired final position. An analog encoder is operatively connected to the printer component, and a threshold device is connected to the analog output of the analog encoder. The position of the printer component is determined from the digital output of the threshold device and a digitization of the analog output of the analog encoder.

In-flight entertainment systems provide entertainment for passengers on commercial airline flights. Presently, usually on longer flights, video entertainment is commonly available on in-flight passenger entertainment systems. In-flight entertainment systems can display video on a variety of display monitors ranging from a conventional CRT display to a more modern Liquid Crystal Display (LCD). Generally most displays are connected to the aircraft electronic system via a ARINC 722 connector. The ARINC 722 connector commonly provides an electrical interface between the aircraft and the video system, whether the video system is a CRT or LCD type monitor. With the increasing use of LCD monitors there is a greater need for the ability of the display monitor to be able to report its status. The need for status reporting is increased because the LCD monitors are often greater in number than the prior art CRT monitors and because malfunctions are less obvious. Several methods for providing status information from video displays have been proposed. Embodiments of the present invention comprise a system in which data can be requested by repeating commands, such as turn on, a number of times within a predetermined time interval. Because embodiments of the invention use an existing command, which can be the repeated without affecting the functioning of legacy systems, the need for modification of the airline and monitor systems is greatly reduced.