Datalink throughput reduction via energy detection

• US 7,664,512 B2
• Filed: 08/10/2006
• Issued: 02/16/2010
• Est. Priority Date: 08/10/2006
• Status: Expired due to Fees

• Current Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Original Assignee: L-3 Communications Integrated Systems LP (L3Harris Technologies, Inc.)
• Inventors: Parker, John M, Le, Phuong H, Robertson, Mark A, Reid, David L, Chung, Hyo K
• Primary Examiner(s): Corsaro; Nick
• Assistant Examiner(s): Ngo; Chuong A
• Application Number:
  US11/463,804
• Publication Number:
  US 20080039039A1
• Time in Patent Office: 1,286 Days
• Field of Search: 455/456, 375/350
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/0226 Transmitters

Abstract

A geolocation system (10) includes an emitter (12), a plurality of collection nodes (14,16,18), and a control station (20). Each collection node includes a receiver (24) that is operable to receive signals transmitted from the emitter (12), generate a reduced data stream that includes only signal data, and communicate the reduced data stream to the control station (20) along with navigation data. The receiver (24) identifies signal data by detecting an energy level of the raw collection data. More specifically, the receiver (24) determines a bandwidth and a signal-to-noise ratio of each portion of the collection data, and identifies each portion as including signal data if both the bandwidth and the signal-to-noise ratio exceed predetermined threshold amounts. The receiver (24) includes a digital signal processing component (36) for performing calculations used by the receiver (24) to determine the bandwidth and the signal-to-noise ratio.

Claims

1. A receiver with reduced data link throughput, the receiver comprising:

a first interface for receiving a wireless signal and for generating signal collection data, wherein the signal collection data includes signal data and non-signal data;

a navigation data circuit for generating and storing navigation data including position and velocity data recorded at the time the first interface receives the wireless signal;

a processor for analyzing the signal collection data to identify portions of the data that include signal data and portions of the data that include only non-signal data;

a second interface for communicating information to an external device via a wireless data link; and

a controller for communicating only the navigation data and the portions of the data that include signal data to the second interface for communication to the external device via the wireless data link.

2. The receiver as set forth in claim 1, wherein the processor analyzes the signal collection data by determining a signal to noise ratio and a bandwidth of each portion of the data, wherein the controller determines that a portion includes signal data only if the signal to noise ratio or the bandwidth of the portion exceeds a pre-determined threshold.

3. The receiver as set forth in claim 2, wherein the controller determines the signal to noise ratio by detecting modulation of a carrier frequency of the signal, and determines the bandwidth by applying a Fourier transform to the data.

4. The receiver as set forth in claim 3, wherein the controller determines the signal to noise ratio by determining the second and fourth moments of the signal and using the second and fourth moments to calculate a kurtosis value of the signal.

5. The receiver as set forth in claim 4, wherein the second moment is defined as

mean(second moment vector_n),

wherein

second moment vector_n=|signal_n|²,

and wherein the fourth moment is defined as

mean(fourth moment vector_n),

wherein

fourth moment vector_n=(second moment vector_n)².

6. The receiver as set forth in claim 4, wherein the controller determines the kurtosis value by dividing the second moment by the square of the fourth moment.

7. The receiver as set forth in claim 4, wherein the controller determines the signal to noise ratio (SNR) according to the equation

$\mathrm{SNR}=10\times$

log 10 ( 2 ⁢

- ⁢

kurtosis + 2 ⁢

- ⁢

kurtosis kurtosis ⁢

- ⁢

1 ) .

8. A geolocation system with reduced data link throughput, the system comprising:

a transmitter for transmitting a wireless signal;

a plurality of mobile receiver platforms, wherein each platform includes—

a circuit for receiving the wireless signal and for generating collection data, wherein the collection data includes signal data and non-signal data and is divided into time blocks of uniform size,

a circuit for generating navigation data indicating a position and a velocity of the platform corresponding to the collection data,

a digital signal processor for determining whether each data block includes signal data by determining a signal to noise ratio and a bandwidth of each stored data block and comparing the signal to noise ratio and the bandwidth to pre-determined threshold values,

a wireless data link interface, and

a controller for communicating the collection data to the digital signal processor, and for communicating qualified data and corresponding navigation data to the data link interface, wherein qualified data includes only data blocks that contain signal data; and

a control station for receiving the data packets communicated by each of the receiver platforms and generating location information of the transmitter based on the data packets.

9. The receiver as set forth in claim 8, wherein each mobile receiver platform further includes a precision time source for enabling each receiver platform to generate the time blocks of data according to time parameters that are substantially identical to time parameters used by the other receivers to generate time blocks of data.

10. The receiver as set forth in claim 8, wherein the digital signal processor determines the signal to noise ratio by detecting modulation of a carrier frequency, and determines the bandwidth by applying a Fourier transform to the data.

11. The receiver as set forth in claim 10, wherein the digital signal processor determines the signal to noise ratio by determining the second and fourth moments of the signal and using the second and fourth moments to calculate a kurtosis value of the signal.

12. The receiver as set forth in claim 11, wherein the second moment is defined as

mean(second moment vector_n),

wherein

second moment vector_n=|signal_n|²,

and wherein the fourth moment is defined as

mean(fourth moment vector_n),

wherein

fourth moment vector_n=(second moment vector_n)².

13. The receiver as set forth in claim 11, wherein the digital signal processor determines the kurtosis value by dividing the second moment by the square of the fourth moment.

14. The receiver as set forth in claim 11, wherein the digital signal processor determines the signal to noise ratio (SNR) according to the equation

$\mathrm{SNR}=10\times$

log 10 ( 2 ⁢

- ⁢

kurtosis + 2 ⁢

- ⁢

kurtosis kurtosis ⁢

- ⁢

1 ) .

15. A method of data collection that reduces throughput of a data link between a receiver and a control station, the method comprising:

receiving a wireless signal and generating signal collection data at the receiver, wherein the signal collection data includes signal data and non-signal data and is divided into data blocks;

generating navigation data including a position and a velocity of the receiver corresponding to the collection data;

analyzing each data block at the receiver to determine whether the data block includes signal data; and

communicating qualified data and navigation data from the receiver to the control station via a wireless data link, wherein the qualified data includes only data blocks that include signal data.

16. The method as set forth in claim 15, wherein analyzing each data block at the receiver to determine whether the data block includes signal data involves determining a signal to noise ratio of the data and a bandwidth of the data.

17. The method as set forth in claim 16, wherein determining the signal to noise ration involves detecting modulation of a carrier frequency of the signal and determining the bandwidth involves applying a Fourier transform to the data.

18. The method as set forth in claim 17, wherein determining the signal to noise ratio includes determining the second and fourth moments of the signal and using the second and fourth moments to calculate a kurtosis value of the signal.

19. The method as set forth in claim 18, wherein the second moment is defined as

mean(second moment vector_n),

wherein

second moment vector_n=|signal_n|²,

and wherein the fourth moment is defined as

mean(fourth moment vector_n),

wherein

fourth moment vector_n=(second moment vector_n)².

20. The method as set forth in claim 18, wherein the kurtosis value is determined by dividing the second moment by the square of the fourth moment.

21. The method as set forth in claim 18, wherein the signal to noise ratio (SNR) is determined according to the equation

$\mathrm{SNR}=10\times$

log 10 ( 2 ⁢

- ⁢

kurtosis + 2 ⁢

- ⁢

kurtosis kurtosis ⁢

- ⁢

1 ) .