Abstract: An emergency vehicle audible warning system and method for improving emergency vehicle mission effectiveness and reducing the undesirable side effects of emergency vehicle audible warning systems. The audible warning system projects different selectable sound phrases that indicate varying levels of urgency. Periods of silence are included between sound phrases for, among other purposes, improving listener attentiveness and allowing operators of emergency vehicles to hear other approaching emergency vehicles. Urgency is further indicated by varying the duration of silent period between sound phrases with speed changes of the emergency vehicle. Higher and broader frequency spectrums compared to typical warning systems are utilized in order to better penetrate other vehicles and to project a less harsh, yet still effective warning.

Abstract: A frequency control system is provided for controlling the radio frequency of a mechanically tuned coaxial magnetron under a wide variety of environmental conditions by initially tuning the magnetron according to resident tuning data and in response to a received frequency command signal, directly measuring the frequency of the magnetron output, comparing the frequency command signal with the actual frequency of each of a series of sampled output pulses, modifying a dynamically adapting calibration function according to any differences found during the comparison, retuning the magnetron according to the modified calibration function, and repeating the process to maintain the magnetron output frequency in agreement with frequency command signals. The coefficients of the calibration function converge to an optimum set of values within a few pulses.

Abstract: A trinary inverter for a digital logic circuit of the type having relatively positive, negative and zero signal voltage values is implemented with CMOS transistors and has the advantages of low power dissipation and low output impedance in the zero signal state. The inverter comprises first, second and third inverter branches, where each branch is formed of a pair of complementary MOS field effect transistors. The inverted output signals from each branch are used to produce a device output signal having the desired voltage transfer characteristics.

Abstract: A method and apparatus are disclosed for converting a digital TACAN output into an analog potentiometer input suitable for an analog navigation computer. The apparatus includes an input register for temporarily storing a digital TACAN output signal. A nines complement generation circuit is utilized to generate the nines complement of the digital TACAN output signal and the nines complement is temporarily stored in a second register. The data in each register is then utilized to control one of two identical resistive circuits which are coupled to a common output node so that the total resistance in both circuits is always equal to a selected total resistance. In a preferred embodiment of the present invention, a plurality of optically coupled solid state relays are utilized to control the resistive circuits.

Abstract: A computerized flight inspection system is disclosed. The system of the present invention may be utilized to generate an accurate reference location with respect to an airport runway for an aircraft having an inertial navigation system. A selected geometric pattern having a highly unambiguous autocorrelation function is placed on at least one end of the runway. A video line scanning camera mounted to the aircraft is then utilized to scan the geometric pattern in a line generally perpendicular to the line of flight. The output of the video line scanning camera is then correlated with a stored reference pattern to generate a signal indicative of the detection of the geometric pattern on the runway. A laser altimeter is mounted to the aircraft and utilized to generate an accurate signal indicative of the aircraft altitude with respect to the runway pattern. The outputs of the correlation circuit and the laser altimeter are then utilized to correct data from the inertial navigation system.