A demodulator for signals angularly related to the position of a rotor of a synchro or resolver uses, in one embodiment, only one transformer in a circuit for subtracting, adding, and phase shifting the signals to produce a single signal phase shifted in proportion to the rotor angle. In another embodiment, a transformerless circuit uses an operational amplifier to derive the phase shifted signal. The phase shifted signal is compared with a reference signal to produce a rectangular wave with a variable duty cycle, which is integrated to produce a DC voltage representing the rotor angle. A pair of the circuits are used in an altitude warning system connected to synchros for the actual altitude and the command altitude of an aircraft. The derived phase shifted signals from both synchros are compared to produce a rectangular wave with a variable duty cycle, which is integrated and compared with voltages representing preselected altitudes to indicate when the aircraft is at those altitudes.
Resolvers are in common use as angular position sensing devices. Such resolvers normally require difficult to generate sine-wave excitation signals, and extensive decoding circuitry for producing an output signal related to angular position. The subject apparatus utilizes a generator to produce a rectangular-wave timing signal. A logic circuit receives the timing signal and responsively produces first and second rectangular-wave excitation signals, which are delivered to respective stator coils of a resolver. A decoding circuit receives one of the excitation signals and the phase encoded signal magnetically induced in the rotor coil of the resolver, and produces an angular position signal having a duty cycle responsive to the phase difference between the received signals.
A sensor concentrating system centralizes communication between multiple parameter sensing devices and an application host. As a peripheral device, the sensor concentrating unit establishes a temporal correspondence between range data acquired from multiple optical range sensors with position data acquired from a shaft encoder. The parameter data are read and sampled according to a user specified criteria such as the time division multiplexing technique. The sampled data is correlated with a data tag generated by the sensor concentrating unit. The correlated data is packeted transmitted from the sensor concentrating unit to a downstream application host for subsequent analysis. The sensor concentrating unit also provides operating parameters for individual parameter sensing devices.
A flight warning system comprises an outside temperature probe for sensing outside temperature, a gyroscope for sensing aircraft bank angle, a static transducer for sensing static pressure, and a dynamic pressure sensor for receiving total pressure from a pitot tube. A computer is responsive to the gyroscope, static transducer, outside temperature probe and dynamic pressure sensor calculates whether the aircraft is entering a stall condition by comparing the aircraft's bank angle with the stall bank angle. The computer can also calculate whether sufficient altitude exists for the aircraft to safely return to a field after a power failure. An output device can also be provided for indicating the existence of said sufficient altitude, and a stall indicator can be provided for indicating whether the aircraft is entering a stall condition. A method for determining the existence of a stall condition with the aircraft is also disclosed.
