Narco Scientific Industries, Inc.

Narco Avionics, Inc.

John F Smith

Boyd M McClaskey

McClaskey, Boyd M

Robert A Bongiorno

Brian H Ham

Ricardo C Salinas

Henry M Hund

A hand held navigational-communications transceiver is compressed into a case having a volume of about 37 cubic inches by defining functional implementation for VOR (VHF omni-directional range) navigation. The transceiver can be selectively switched to process and display directional radial information. A microprocessor circuit provides primary circuitry information in combination with transceiver function software held in ROM (read only memory). A plurality of pre-programmed frequencies may be selected.

Portable navigational communications transceiver

A radio receiver squelch circuit operative as a function of a comparison of the audio component level of the detected signal with the noise component level, so as to amplify and pass signals when the audio component exceeds the noise component by a predetermined ratio and to shunt the signals, thus squelching any output, when the noise component exceeds the audio component by a predetermined ratio. The circuit incorporates a hysteresis function such that the audio level required to initiate squelch is less than that required to break squelch.

Automatic squelch circuit with hysteresis

In a radio receiver, noise limiter apparatus specifically designed to clip impulse noise and to pass the audio signal undistorted up to about 80% carrier modulation. The noise limiter comprises a clipping circuit which is normally turned on by the audio signal to pass same, and a noise impulse amplifier branch containing an amplifier which is edgetriggered to cause clipping during the presence of noise impulses and to eliminate an output from the impulse amplifier when an audio signal is present.

Noise limiter

For use in a channel synthesizer utilizing a pulse swallowing phase locked loop, an eight bit code represents the megahertz component of the selected channel. An eight stage shift register is preloaded with the coded version of the selected megahertz component, and exclusive OR logic responsive selectively to the first, third, fifth, and eighth stages generates data for the first stage during the next shift. NAND logic responsive to the various stages detects presence of certain code combinations which are representative of terminal count states. Each terminal count pulse is utilized for comparison with the frequency reference in the phase locked loop, and also in a feedback arrangement to reset the registers to their preloaded states.

Code and generating means for avionics communciations synthesizer

In order to produce signals having a desired communication channel frequency, a phase locked loop is provided, along with appropriate frequency division. For channels in the megahertz range having bandwidth in the kilohertz range, a kilohertz reference is provided for comparison, to drive the voltage controlled oscillator. The oscillator output is divided by the megahertz quantity, and by optional division multiples in the kilohertz channel range. In particular, a first division ratio is utilized for a portion of a reference cycle, and a second division ratio for the remainder of this cycle. Preloaded logic controls the two division rates, and by adjusting the portions of the cycle, correspondingly regulates the effective division ratio for the loop, and yields the proper channel frequency for locking.

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Warminster, PA, United States of America

John F Smith