Automatic navigation station identifier and monitor
OwnerJohn E. Mercerinventor
Life of this patent
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Abstract
This invention relates to a method and apparatus for automatically decoding and monitoring Morse code identifying call letters of radio navigation aids commonly in use for both aircraft and marine transportation, e.g. VOR--very high frequency omni range, ILS--instrument landing system, NDB--non directional beacons, and DME--distance measurement equipment.
Claims16
A method of electronically identifying a radio station by use of a Morse code identifying signal which is transmitted by the station, comprising:
- sensing the noise or signal level in a model signal slice of the radio station signal spectrum which is outside of the Morse code tone frequency and providing a control voltage corresponding to the sensed noise or signal level;
- directing both the station signal and the model signal through an automatic gain control amplifier;
- and
- using the control voltage to automatically adjust the front end gain to the amplifier to compensate for any differences in receiver volume, noise, and/or signal strength.
A method of electronically identifying a radio station by use of a Morse code signal which is transmitted by the station, comprising:
- receiving from a selected radio station, a Morse code signal;
- directing such signal to an automatic gain control amplifier;
- directing the output of the automatic gain control amplifier to a first bandpass filter which corresponds to the tone frequency of the Morse code signal;
- also directing the output from the automatic gain control amplifier to a second bandpass filter which has a center frequency different from the tone frequency of the Morse code signal;
- detecting the output of the second bandpass filter and feeding the output signal back to the automatic gain control amplifier in the form of an automatic gain control signal, to automatically adjust front end gain to the amplifier to compensate for any differences in receiver volume, noise, and/or signal strength;
- subtracting the output of the first bandpass filter from the output of the second bandpass filter in a difference amplifier;
- directing the output of the difference amplifier through a lowpass filter;
- utilizing a cut-off frequency in the lowpass filter which will allow frequencies associated with the pulse rate of the Morse code identifying signal to pass through with almost no attenuation;
- and
- using the output of the lowpass filter to identify the radio station.
Apparatus for electronically detecting a Morse code signal which is transmitted by a radio station, comprising:
- a first bandpass filter which corresponds to the tone frequency of the Morse code signal;
- a second bandpass filter which has a center frequency which is different from the tone frequency of the Morse code signal;
- means for receiving, from a selected radio station, a Morse code signal;
- means for delivering the Morse code identifying signal to both the first and second bandpass filters;
- means for subtracting the output of the first bandpass filter from the output of the second bandpass filter to produce an identifier signal;
- and
- station identifying means operable in response to an identifier signal to identify the station transmitting the Morse code signal.
Dependencies are inferred from the claim text.