초록 ▼

The capacity of a Mode-S ADS-B surveillance radar system is increased by sectorizing the radar system by the use of a directional array of Mode-S, quarter wavelength, single element, stub antennas. The ensemble of signals from the array of Mode-S antenna elements is processed electronically. The sig

The capacity of a Mode-S ADS-B surveillance radar system is increased by sectorizing the radar system by the use of a directional array of Mode-S, quarter wavelength, single element, stub antennas. The ensemble of signals from the array of Mode-S antenna elements is processed electronically. The signal processing/receiver architecture increases the capacity of the Mode-S ADS-B system to be capable of effectively functioning within a highly congested airspace.

대표청구항 ▼

1. A Mode-S digital receiving system for receiving and processing Mode-S signals in an aircraft operating in a dense environment of aircraft comprising:a. a spatial array of Mode-S antenna elements mounted on the aircraft;b. a signal processing receiver for producing and processing a separate signal

1. A Mode-S digital receiving system for receiving and processing Mode-S signals in an aircraft operating in a dense environment of aircraft comprising:a. a spatial array of Mode-S antenna elements mounted on the aircraft;b. a signal processing receiver for producing and processing a separate signal for each separate antenna element;c. at least one analog to digital (A/D) converter for converting the signals for the separate antenna elements to corresponding digital signals;d. a multiplexer for sequentially and periodically coupling at least one signal or digital signal from the separate antenna elements;e. a squitter filter for determining the presence of a squitter preamble in a Mode-S signal received by the receiving system;f. a digital signal processing unit, responsive to the determined presence of the Mode-S signal, for processing and adjusting complex weights of the digital signals for the separate antenna element to maximize the signal-to-noise ratio of the received Mode-S signal;g. a Mode-S receiver, coupled to the output of the digital signal processing unit, for processing and identifying technical data conveyed by the Mode-S signal. 2. The Mode-S digital receiving system of claim 1, further comprising:a. a memory/buffer stores the digital signals in sequence therein;b. a controller unit is coupled to the output of the squitter filter and controls the memory/buffer and the digital signal processing unit, wherein the controller unit, upon being notified by the squitter filter that a squitter preamble is present,isolates the Mode-S signal in the memory/buffer wherein the Mode-S signal is retained until processing is completed,directs the digital signal processing unit to adjust complex weights of all antenna element digital signals to maximize the signal-to-noise ratio of the isolated Mode-S signal, andafter the signal-to-noise ratio has been maximized, the controller unit directs the digital signal processing unit to output the Mode-S signal to the Mode-S receiver, and directs the memory/buffer to resume sequenced operation. 3. The Mode-S digital receiving system of claim 2, wherein:a. the analog to digital (A/D) converter produces a pair of time offset digital signals for each signal;b. a Hilbert Transform filter Hilbert transforms one of the pair of time offset digital signals to produce a quadrature I and Q sample pair which is directed as an input to the memory/ buffer. 4. The Mode-S digital receiving system of claim 1, wherein each Mode-S antenna element comprises a quarter wavelength, single element, stub antenna. 5. The Mode-S digital receiving system of claim 1, wherein in the signal processing receiver, each antenna element has associated therewith:a. a preamplifier for amplifying an output of the antenna element;b. a frequency down converter for frequency down converting an output of the preamplifier; andc. a filter for filtering an output of the down converter to remove out of band signal energy, to produce a signal output. 6. The Mode-S digital receiving system of claim 2, wherein the memory/buffer comprises first and second cascaded memory/buffer units. 7. The Mode-S digital receiving system of claim 6, wherein the controller unit, upon being notified that the squitter preamble is present, isolates the Mode-S signal in the second memory/buffer unit. 8. The Mode-S digital receiving system of claim 1, wherein the squitter filter comprises a surface acoustic wave filter which constantly convolves a filtered output of an antenna element with a squitter preamble signature to determine the presence of the squitter preamble. 9. A method for receiving and processing Mode-S signals in an aircraft operating in a dense environment of aircraft comprising:a. mounting a spatial array of Mode-S antenna elements on the aircraft;b. producing and processing a separate signal for each separate antenna element;c. converting the signals for the separate antenna elements to corresponding digital signals;d. sequentially and p eriodically coupling at least one signals or digital signals from the separate antenna elements;e. determining the presence of a squitter preamble in a Mode-S signal received by a receiving system;f. in response to the determined presence of the Mode-S signal, processing and adjusting complex weights of the digital signals for the separate antenna element to maximize the signal-to-noise ratio of the received Mode-S signal;g. processing and identifying technical data conveyed by the maximized signal-to-noise ratio Mode-S signal. 10. The method of claim 9, comprising:a. storing the digital signals in sequence in a memory/buffer;b. upon determining that presence of the squitter preamble,isolating the Mode-S signal in the memory/buffer wherein the Mode-S signal is retained until processing is completed,adjusting complex weights of all antenna element digital signals to maximize the signal-to-noise ratio of the isolated Mode-S signal, andafter the signal-to-noise ratio has been maximized, outputting the Mode-S signal, and resuming sequenced operation of the memory/buffer. 11. The method of claim 10, comprising:a. producing a pair of time offset digital signals for each signal;b. transforming one of the pair of time offset digital signals to produce a quadrature I and Q sample pair which is directed as an input to the memory/buffer. 12. The method of claim 9, comprising mounting a spatial array of quarter wavelength, single element, stub antennas. 13. The method of claim 9, comprising:a. preamplifying an output of each antenna element;b. frequency down converting an output of each preamplifier; andc. filtering an output of each down converted output to remove out of band signal energy, to produce a signal output. 14. The method of claim 10, comprising providing first and second cascaded memory/buffer units, and upon being notified of the presence of the squitter preamble, isolating the Mode-S signal in the second memory/buffer unit. 15. The method of claim 9, comprising employing a surface acoustic wave filter which constantly convolves a filtered output of an antenna element with the squitter preamble signature to determine the presence of the squitter preamble.