SYSTEM AND METHOD FOR CONTROLLING INTERMODULATION INTERFERENCE

• US 20090023403A1
• Filed: 07/20/2007
• Published: 01/22/2009
• Est. Priority Date: 07/20/2007
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: LaBerge, E.F. Charles
• Granted Patent: US 7,983,635 B2
• Time in Patent Office: Days
• US Class Current: 455/114.200
• CPC Class Codes: H04B 15/02 Reducing interference from electric apparatus by means located at or near the interfering apparatus
• CPC Class Codes: H04B 7/18517 Transmission equipment in earth stations

Abstract

In one embodiment, a method of controlling intermodulation (IM) interference is provided. The method comprises determining if an IM product spectrum overlaps the spectrum of an assigned receive frequency and determining when transmissions from at least two transmitters are to overlap in time. If the IM product spectrum overlaps the assigned receive frequency spectrum, it is determined if a signal is being propagated on the receive frequency when the transmissions from the at least two transmitters are to overlap in time. If a signal is not being propagated on the receive frequency, the at least two transmitters are allowed to transmit the overlapping transmissions; and if a signal is being propagated on the receive frequency, control steps are initiated to reduce the effects of IM interference

Claims

1. A method of controlling intermodulation (IM) interference, the method comprising:

determining if at least two transmitters are present, each transmitter assigned a separate transmit frequency;

determining when transmissions from the at least two transmitters are to overlap in time; and

initiating control steps to reduce the effects of IM interference when transmissions from the two transmitters are to overlap in time.

2. The method of claim 1, wherein initiating control steps includes at least one of:

delaying transmission from one of the at least two transmitters;

adjusting the transmission power of at least one of the at least two transmitters; and

allowing the received signal to be dropped.

3. The method of claim 1, wherein initiating control steps includes initiating control steps based on aeronautical priority, precedence, and preemption standards.

4. The method of claim 1, further comprising

determining if an IM product spectrum, produced by the at least two transmitters, overlaps the spectrum of an assigned receive frequency;

if the IM product spectrum overlaps the assigned receive frequency spectrum, determining if a signal is being propagated on the receive frequency when the transmissions from the at least two transmitters are to overlap in time;

if a signal is not being propagated on the receive frequency, allowing the at least two transmitters to transmit the overlapping transmissions; and

if a signal is being propagated on the receive frequency, initiating control steps to reduce the effects of IM interference.

5. The method of claim 4, wherein determining if a signal is being propagated on the receive frequency comprises one of:

listening for a signal on the assigned receive frequency for a predetermined time period; and

analyzing a receive schedule to determine when a signal is scheduled to be received.

6. The method of claim 1, wherein determining when transmissions from at least two transmitters are to overlap in time includes one of:

analyzing a transmit schedule for each of the at least two transmitters; and

each time one of the at least two transmitters is ready to transmit, determining if the transmission is to overlap a transmission from another of the at least two transmitters.

7. The method of claim 1, further comprising:

measuring the amplitude of the IM product;

comparing the measured IM product amplitude to a predetermined threshold; and

ending the method without initiating control steps if the measured IM product is below the predetermined threshold.

8. A multi-carrier radio comprising:

a plurality of transceivers, each transceiver assigned a transmit frequency and a receive frequency; and

a processing unit configured to initiate control steps to reduce the effects of intermodulation (IM) interference when the processing unit determines that at least two of the plurality of transceivers are to overlap transmissions in time.

9. The multi-carrier radio of claim 8, wherein the processing unit is further configured to flag each assigned receive frequency for which the processing unit determines that the IM product spectrum generated by the at least two of the plurality of transceivers overlaps the assigned receive frequency spectrum, wherein the processing unit checks for a signal on each flagged receive frequency when the processing unit determines that the at least two transceivers are to overlap transmissions, the processing unit initiating control steps to reduce the effects of IM interference when a signal is detected on the corresponding flagged receive frequency and allowing the at least two transmitters to overlap transmissions if no signal is detected on the corresponding receive frequency.

10. The multi-carrier radio of claim 8, wherein the processing unit is further configured to initiate at least one of a transmission delay for at least one of the at least two transceivers which generate the corresponding IM product;

an adjustment of the transmission power of at least one of the at least two transceivers which generate the corresponding IM product; and

a drop of the signal detected on the corresponding flagged receive frequency.

11. The multi-carrier radio of claim 8, wherein the processing unit is further configured to determine if the amplitude of an IM product generated by at least two of the plurality of transceivers is greater than a predetermined threshold, wherein the processing unit does not initiate control steps if the amplitude of the IM product does not exceed the threshold.

12. The multi-carrier radio of claim 8, wherein the processing unit is further configured to initiate control steps based on aeronautical priority, precedence, and preemption standards.

13. The multi-carrier radio of claim 8, wherein the processing unit determines when the at least two transceivers are to overlap transmissions by analyzing a transmit schedule for each of the at least two transceivers.

14. The multi-carrier radio of claim 8, wherein the plurality of transceivers are configured to transceive signals using an Inmarsat data service.

15. A program product comprising program instructions embodied on a processor-readable medium for execution by a programmable processor, wherein the program instructions are operable to cause the programmable processor to:

determine if at least two transmitters are present, each transmitter assigned a separate frequency;

determine when transmissions from the at least two transmitters are to overlap in time; and

initiate control steps to reduce the effects of IM interference when transmissions from the at least two transmitters are to overlap in time.

16. The program product of claim 15, wherein the program instructions are further operable to cause the programmable processor to initiate one of:

delaying transmission from one of the at least two transmitters;

adjusting the transmission power of at least one of the at least two transmitters; and

allowing the signal propagated on the receive frequency to be dropped.

17. The program product of claim 15, wherein the program instructions are further operable to cause the programmable processor to initiate control steps based on aeronautical priority, precedence, and preemption standards.

18. The program product of claim 15, wherein the program instructions are further operable to cause the programmable processor to:

determine the spectrum of an intermodulation (IM) product generated by the at least two transmitters;

determine if the IM product spectrum overlaps the spectrum of an assigned receive frequency;

determine if a signal is being propagated on the receive frequency when transmissions from the at least two transmitters are to overlap in time;

allow the transmissions from the at least two transmitters to overlap if a signal is not being propagated on the receive frequency; and

initiate control steps to reduce the effects of IM interference if a signal is being propagated on the receive frequency when the transmission from the at least two transmitters are to overlap in time and the IM product spectrum overlaps the assigned receive frequency spectrum.

19. The program product of claim 18, wherein the program instructions are further operable to cause the programmable processor to determine when transmission from the at least two transmitters are to overlap by analyzing a transmit schedule for each of the at least two transmitters.

20. The program product of claim 15, wherein the program instructions are further operable to cause the programmable processor to:

measure the amplitude of a test IM product on a receive frequency;

compare the measured IM product amplitude to a predetermined threshold; and

end processing of the program instructions without initiating control steps if the measured IM product is below the predetermined threshold.