Simultaneous access to all channels of a superhet radio

System enables radio contact of air, sea, and land vehicles operating in restricted areas


The threat of terrorism has increased the prevalence of temporary flight restrictions (TFRs) around such things as sporting events or gatherings of world leaders. TFR’s may also be established in the event of military operations or hazardous flight situations related to natural events such as forest fires and volcanic eruptions.

During the week of February 11, 2018, there were 44 TFRs issued in the U.S. While pilots are notified of these restricted areas, there is always the chance of a plane unintentionally wandering into a restricted space. In such a case, an air traffic controller attempts to hail the small aircraft but, communication bands of aviation radios have over 800 channels and the ATC does not know what channel the small aircraft pilot is monitoring. This can lead to necessary responses that are expensive and potentially deadly.

Navy scientists have developed a system to avoid the possibility of the above scenario. The system allows a ground controller to hail the pilot on all channels simultaneously. An omnidirectional antenna is used to create a hemispherical transmission and reception zone where the size of the zone can be dependent upon the antenna’s transmitter power within the controlled airspace with an un-modulated frequency. This is combined with a directional antenna transmitting a narrow beam at the aircraft.

This narrow beam can be modulated with a message and may extend outside of the zone created by the omnidirectional antenna, but only the aircraft that receives both frequencies, i.e. is within the zone created by the omnidirectional antenna transmitting the first frequency and is within the directional antenna transmitting the narrow beam on a second frequency will receive the desired message.  In this instance, the aircraft will receive the message on all channels simultaneously.

This US patent 9,748,980 is a divisional of US patent 9,742,441.

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