Narco Scientific Industries, Inc.

Narco Scientific, Inc.

Frank Patterson Smith, 2nd

Ronald Lee Powell

John M Ferrara

John W Bail

A navigational unit having a time-shared mode of operation for handling a plurality of different navigational signals is provided wherein IF components within the unit may have a dual dedication, i.e., used in common for handling all signals while normally present separate front end components and navigational display components may be dedicated exclusively to each separate signal, a central timing and control component coordinating the total operation.

Navigation unit having time shared operation

In an information receiving apparatus having a time-shared mode of operation for simultaneously receiving a plurality of information carrying signals, at least one signal of which includes an identification tone superimposed thereupon, a tone reconstitution scheme for providing a continuous tone from a received tone signal which contains absences of tone signal due to the time-shared partial duty dedication of the receiver to that signal and its superimposed tone.

Identification tone reconstitution in a time shared navigational receiver

A general aviation navigational receiver is provided with a digital channel selection wherein a channel selection knob on the aircraft control board may be operated to control the functioning of a digitally implemented frequency synthesizer which in turn controls the operation of a voltage controlled oscillator for providing frequency signals to an RF mixer of the unit, the frequency synthesizer being programmed for both possible VOR/LOC and GS channel frequencies wherein switching between frequencies is accomplished in synchronism with the basic clock within the synthesizer greatly reducing transient changeover time.

Time shared operation of navigational unit

A circuit which allows the operation of a VOR receiver in the presence of unwanted interference signals without sacrificing a fast response to omnirange bearing selector changes. A switching-type synchronous filter is used to filter the 30 Hz AM channel signal in the receiver. The narrow bandwidth of this synchronous filter rejects unwanted interference signals without introducing phase shift into the desired signal. The switching signal for the synchronous filter is generated by the FM channel in such a manner that the switching filter center frequency follows the input frequency. The use of a synchronous filter allows rejection of interfering AM signals that lie outside a narrow pass band, while allowing the receiver to follow variations in frequency of the transmitted signal.

Synchronous filter for VOR systems

A ranging timer allows decoded data pulses to toggle a flip flop, thereby initiating a transmission cycle. In a specific embodiment, the data pulses condition a second flip flop to energize the DME transceiver. During the next negative excursion of a 96 microsecond reference clock, the second flip flop is toggled, and during the next period of the reference clock, the decoder is disabled, the transmitter-modulator is energized, the ranging timer is enabled, and the first flip flop is reset. Since the time between the decoded data pulses is variable, jitter is built into the commencement of each transmission cycle.

DME timing apparatus and methods

In a DME system, the least significant decade of the present aircraft to ground station distance is maintained encoded in a memory, and an up-down counter maintains a variable count. The complement of the present distance is compared with the present count, and when a difference is detected, a logical pulse increments the counter and also indicates passage of the aircraft through another distance interval. The sense of the difference between the present distance and the count also is monitored, responsive to which the direction of the count is controlled.

Apparatus and method for detecting a digital change in data

A voltage controlled oscillator provides a pulse signal which, when frequency scaled, is representative of aircraft velocity. Pulses representative of passage of the aircraft over distance intervals are coupled to one input of a comparator-integrator, and the VCO output pulses are further divided and coupled to the other input terminal of the comparator-integrator. The integration voltage controls the VCO. The VCO signal is frequency scaled and fed to a counter, the output count of which is strobed periodically and decoded to yield velocity.

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Dresher, PA, United States of America

Frank Patterson Smith, 2nd