System and method for fully self-contained calibration of an antenna array

• US 6,133,868 A
• Filed: 06/05/1998
• Issued: 10/17/2000
• Est. Priority Date: 06/05/1998
• Status: Expired due to Term

• Current Assignee: Kathrein-Werke KG. (Kathrein SE)
• Original Assignee: Metawave Communications Corp.
• Inventors: Melville, Michael G., Butler, Ray K., Elson, J. Todd, McClive, Curtis F.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/092,429
• Time in Patent Office: 865 Days
• Field of Search: 342/165, 342/169, 342/170, 342/171, 342/172, 342/173, 342/174, 342/175, 342/195, 342/368, 342/371, 342/372
• US Class Current: 342/174
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices

Abstract

Systems and methods are disclosed for providing calibration of the phase relationships of signals simulcast from a transmission system. In a preferred embodiment, a calibration signal is introduced into the transmission system and provided to various antenna elements. Samples of the calibration signal are taken at a point very near the antenna elements so as to sample phase shifts introduced by the transmission system. The signals of sets of the antenna elements are combined after sampling for transmission down the antenna mast to the active circuitry of the present invention. Accordingly, the present invention operates to selectively energize antenna elements of the sets so as to provide a single calibration signal down the combined signal path. Through reference to sampled signals one at a time, the present invention determines a necessary phase adjustment to result in the desired phase relationship of the signals at the antenna elements.

Claims

1. A system for calibrating a particular signal attribute of a first signal of a plurality of signals, said calibrated signal attribute of said first signal having a predetermined relationship to other ones of said plurality of signals, said system comprising:

means for introducing a known signal into a multi-beam communication system having at least a discrete portion of a signal path associated with each of said plurality of signals, wherein said known signal is provided to multiple ones of said discrete portions of signal path;

means for sampling said known signal at the discrete portion of signal path associated with said first signal and at the discrete portion of signal path associated with said other ones of said plurality of signals;

means for determining a relationship of said particular attribute of said first signal with respect to said particular attribute of said other ones of said plurality of signals; and

means utilizing said determined relationship for adjusting circuitry disposed in said discrete portion of signal path associated with said first signal to provide said predetermined relationship of said first signal with respect to said other ones of said plurality of signals.

2. The system of claim 1, wherein said known signal is a signal native to said communication system.

3. The system of claim 1, wherein said known signal is a calibration signal not native to said communication system.

4. The system of claim 1, wherein said introducing means and said sampling means are disposed in said communication system so as to pass said known signal through substantially all of a transmission signal path of said communication system.

5. The system of claim 1, wherein said determining means comprises:

means for comparing samples of said known signal with an exemplary of said known signal;

means for determining said particular signal attribute change between each of said compared samples of said known signal and said exemplary of said known signal; and

means for comparing said determined changes to determine said relationship of said particular attribute of said first signal with respect to said particular attribute of said other ones of said plurality of signals.

6. The system of claim 1, wherein said adjusting means comprises:

processor based means for controlling said circuitry, wherein said controlling means comprises;

a control signal interface coupled to said circuitry; and

a control signal interface coupled to a selection circuit, said

selection circuit coupled between said sampling means and said determining means and providing selection between groups of sampled known signals, wherein said first signal and said other ones of said plurality of signals are included in a same first group of said groups.

7. The system of claim 6, wherein said circuitry provides selective interruption of ones of said discrete portion of signal paths, and wherein said circuitry allows a single signal of said first group to pass at a time under control of said controlling means.

8. The system of claim 7, wherein said circuitry allows signals of said plurality of signals of a second group of said groups to pass simultaneously with allowing said single signal of said first group to pass.

9. The system of claim 8, wherein said sampling means comprises:

means for combining signals of said first group of said groups, wherein a single signal path is provide from said combining means to said determining means.

10. The system of claim 8, wherein said determining means comprises:

means for comparing a first sampled signal of said first group selected by said selection circuit with an exemplary of said known signal;

means for determining an attribute change between said compared first sampled signal and said exemplary of said known signal;

means for comparing a second sampled signal of said first group selected by said selection circuit with an exemplary of said known signal;

means for determining an attribute change between said compared second sampled signal and said exemplary of said known signal; and

means for comparing said attribute change of said first samples signal and said second sampled signal to determine said relative attribute difference with respect to said first sampled signal and said second sampled signal.

11. The system of claim 1, wherein said system is disposed to provide only passive components on an antenna structure of said communication system.

12. The system of claim 1, wherein said particular signal attribute is a phase of said first signal.

13. The system of claim 1, wherein said particular signal attribute is an amplitude of said first signal.

14. A method for calibrating a signal attribute of a first signal of a plurality of signals wherein said plurality of signals include at least two mutually exclusive sets of signals, said first signal being associated with a first set of said at least two sets, said calibrated signal attribute of said first signal having a predetermined relationship to a second signal of said first set, said method comprising the steps of:

introducing a known signal into a communication system having at least a discrete portion of a signal path associated with each of said plurality of signals, wherein said known signal is provided to multiple ones of said discrete portions of signal path including at least the signal path associated with said first signal and the signal path associated with said second signal;

sampling said known signal at the discrete portion of signal path associated with said first signal and at the discrete portion of signal path associated with said second signal;

determining an attribute of said first signal relative to said second signal; and

adjusting with reference to said determined attribute said signal attribute of said first signal to result in a predetermined signal attribute relationship between said first signal and said second signal as sampled at said discrete portion of signal path.

15. The method of claim 14, wherein said adjusting step comprises the step of:

controlling circuitry disposed in said discrete portion of signal path associated with said first signal, wherein said circuitry is disposed substantially more near in the signal path to a source of said first signal than is a point of said discrete portion of signal path said known signal is sampled.

16. The method of claim 15, wherein said determining step comprises the steps of:

comparing a sample of said first signal with an exemplary of said known signal;

determining an attribute change between said first signal and said exemplary of said known signal;

comparing a sample of said second signal with an exemplary of said known signal;

determining an attribute change between said second signal and said exemplary of said known signal; and

comparing said attribute changes of said first and second signals to determine said relative attribute difference.

17. The method of claim 15, wherein said determining step comprises the steps of:

comparing a sample of said first signal with a sample of said second signal to determine said relative attribute difference.

18. The method of claim 15, wherein said controlling step comprises the step of:

adjusting the amplitude of a signal combined in-phase and quadrature to provide a desired phase shift in said first signal.

19. The method of claim 14, wherein said multiple ones of said discrete portions of signal path said known signal is introduced into includes signal paths of a second set of said at least two sets.

20. The method of claim 19, wherein said sampling step comprises the steps of:

combining signals sampled from the discrete portions of signal path associated with said first set of signals into a first common signal;

combining signals sampled from the discrete portions of signal path associated with said second set of signals into a second common signal;

controlling a selection circuit providing switchable communication of said first and second common signal to a signal attribute detector operable in said determining step, wherein said first common signal is communicated to said attribute detector.

21. The method of claim 20, further comprising the steps of:

interrupting ones of said discrete portions of signal path of said first set of signals, wherein a single signal of said first set is available for sampling at said sampling step at any one time.

22. The method of claim 20, wherein said interrupting step does not interrupt said discrete portions of signal path of said second set of signals when interrupting said ones of said first set of signals.

23. The method of claim 14, wherein said particular signal attribute is a phase of said first signal.

24. The method of claim 14, wherein said particular signal attribute is an amplitude of said first signal.

25. A phased array antenna system having a plurality of individual antennas arranged to simultaneously broadcast a signal such that the phase relationship of the signal as it appears at each such individual antenna determines the coverage area of the resultant signal, wherein said phased array is adapted to provide self-contained tuning of the phase of said signal as it appears at each individual antenna to maintain said phase relationship, said system comprising:

means for communicating to each such individual antenna the signal having a desired phase;

means for monitoring the phase of the signal actually received at each such antenna; and

means controlled by said monitoring means for adjusting the phase of each such communicated signal until the desired phase is monitored as having been actually received at each said antenna.

26. The system of claim 25, wherein said monitoring means comprises:

means for restricting communication of the signal to a first selected antenna of said individual antennas at a first time and for restricting communication of the signal to a second selected antenna of said individual antennas at a second time; and

means including a common signal path for accepting the monitored phase of the signal as actually received at said first antenna during said first time and for accepting the monitored phase of the signal as actually received at said second antenna during said second time.

27. The system of claim 26, wherein said monitoring means further comprises:

means for comparing the phase of the signal as actually received at said first antenna during said first time to the phase of the signal as actually received at said second antenna during said second time, wherein said comparison is utilized in control of said adjusting means.

28. The system of claim 27, wherein said comparing means comprises:

means for comparing a monitored signal as actually received at said first antenna during said first time to said signal as actually transmitted, wherein said phase of the signal as actually received at said first antenna is determined; and

means for comparing a monitored signal as actually received at said second antenna during said second time to said signal as actually transmitted, wherein said phase of the signal as actually received at said second antenna is determined.

29. A method of providing self-contained tuning of a phased array antenna system having a plurality of individual antennas arranged to simultaneously broadcast a signal such that the phase relationship of the signal as it appears at each such individual antenna determines the coverage area of the resultant signal, said method comprising the steps of:

communicating the signal having a desired phase to a plurality of individual antennas of the phased array;

monitoring the phase of the signal actually received at each of said plurality of individual antennas; and

adjusting through reference to said monitored phase the phase of each such communicated signal until the desired phase is monitored as having been actually received at ones of said plurality of antennas.

30. The method of claim 29, wherein said monitoring step comprises the steps of:

restricting communication of the signal to a first selected antenna of said plurality of antennas at a first time and for restricting communication of the signal to a second selected antenna of said plurality of antennas at a second time; and

accepting through a common signal path the monitored phase of the signal as actually received at said first antenna during said first time and the monitored phase of the signal as actually received at said second antenna during said second time.

31. The method of claim 30, wherein said monitoring step further comprises the step of:

comparing the phase of the signal as actually received at said first antenna during said first time to the phase of the signal as actually received at said second antenna during said second time, wherein said reference to said monitored phase includes reference to said comparison.

32. The method of claim 31, wherein said comparing step comprises the steps of:

comparing a monitored signal as actually received at said first antenna during said first time to said signal as actually transmitted, wherein said phase of the signal as actually received at said first antenna is determined; and

comparing a monitored signal as actually received at said second antenna during said second time to said signal as actually transmitted, wherein said phase of the signal as actually received at said second antenna is determined.

33. An apparatus for adjusting a phase relationship between at least two signals simulcast from a communication system having a plurality of antenna interfaces distinguishable as at least a first set and a second set of antenna interfaces, wherein said communication system provides a first signal of said at least two signals and a second signal of said at least two signals to individual antenna interfaces of said first set of antenna interfaces, said apparatus comprising:

a calibration signal generator coupled to said communication system, wherein a calibration signal is controllably introduced into said communication system for provision to ones of said plurality of antenna interfaces;

a plurality of combiners coupled to said plurality of antenna interfaces, wherein a first combiner of said plurality combines signals from said first set of antenna interfaces and a second combiner of said plurality combines signals from said second set of antenna interfaces;

a switch matrix coupled said plurality of combiners, wherein a signal associated with a set of antenna interfaces may be switchably selected to the exclusion of signals associated with other sets of antenna interfaces;

a phase detector coupled to said switch matrix and accepting said signal of said selected set of antenna interfaces, wherein said phase detector is also coupled to said calibration signal generator and accepts said calibration signal, and wherein said phase detector determines a phase difference between said accepted antenna set signal and said accepted calibration signal and;

a processor based controller coupled to said phase detector and accepting said determination of said phase difference, said controller also coupled to said switch matrix and providing control of said switch matrix to select a particular said signal of said sets of antenna interfaces, said controller also coupled to said communication system and controlling phase adjustment of ones of said at least two signals in response to said determination of said phase difference.

34. The apparatus of claim 33, wherein said controller provides control of said communication system to provide said calibration signal at said first set of antenna interfaces one antenna interface at a time, wherein said first combiner provides substantially only said calibration signal associated with said one antenna interface to said switch matrix at any one time.

35. The apparatus of claim 34, wherein said controller provides control of said communication system to provide said calibration signal at each of said antenna interfaces of said second set of antenna interfaces, wherein said calibration signal provided by said first combiner includes effects of cross coupling from said calibration signal of said second set of antenna interfaces introduced by said communication system.

36. The apparatus of claim 33, wherein said combiners are coupled to said antenna interfaces to sample said calibration signal without interrupting communication of signals to an antenna.

37. The apparatus of claim 33, wherein said calibration signal generator is coupled to said communication system to introduce said calibration signal without interrupting communication of a signal of said communication system.

38. The apparatus of claim 33, wherein said calibration signal generator is switchably coupled to said communication to provide switchable selection of said calibration signal and a signal of said communication system, wherein contrail of said switchable connection is provided by said controller.

39. A system for calibrating a particular signal attribute of a first signal of a plurality of signals, said calibrated signal attribute of said first signal having a predetermined relationship to other ones of said plurality of signals, said system comprising:

means for introducing a known signal into a communication system having at least a discrete portion of a signal path associated with each of said plurality of signals, wherein said known signal is provided to multiple ones of said discrete portions of signal path;

means for sampling said known signal at the discrete portion of signal path associated with said first signal and at the discrete portion of signal path associated with said other ones of said plurality of signals;

means for determining a relationship of said particular attribute of said first signal with respect to said particular attribute of said other ones of said plurality of signals;

means utilizing said determined relationship for adjusting circuitry disposed in said discrete portion of signal path associated with said first signal to provide said predetermined relationship of said first signal with respect to said other ones of said plurality of signals; and

wherein said determining means comprises;

means for comparing samples of said known signal with an exemplary of said known signal;

means for determining said particular signal attribute change between each of said compared samples of said known signal and said exemplary of said known signal; and

means for comparing said determined changes to determine said relationship of said particular attribute of said first signal with respect to said particular attribute of said other ones of said plurality of signals.

40. A system for calibrating a particular signal attribute of a first signal of a plurality of signals, said calibrated signal attribute of said first signal having a predetermined relationship to other ones of said plurality of signals, said system comprising:

means for introducing a known signal into a communication system having at least a discrete portion of a signal path associated with each of said plurality of signals, wherein said known signal is provided to multiple ones of said discrete portions of signal path;

means for sampling said known signal at the discrete portion of signal path associated with said first signal and at the discrete portion of signal path associated with said other ones of said plurality of signals;

means for determining a relationship of said particular attribute of said first signal with respect to said particular attribute of said other ones of said plurality of signals;

means utilizing said determined relationship for adjusting circuitry disposed in said discrete portion of signal path associated with said first signal to provide said predetermined relationship of said first signal with respect to said other ones of said plurality of signals; and

wherein said adjusting means comprises;

processor based means for controlling said circuitry, wherein said controlling means comprises;

a control signal interface coupled to said circuitry; and

a control signal interface coupled to a selection circuit, said selection circuit coupled between said sampling means and said determining means and providing selection between groups of sampled known signals, wherein said first signal and said other ones of said plurality of signals are included in a same first group of said groups.

41. The system of claim 40, wherein said circuitry provides selective interruption of ones of said discrete portion of signal paths, and wherein said circuitry allows a single signal of said first group to pass at a time under control of said controlling means.

42. The system of claim 41, wherein said circuitry allows signals of said plurality of signals of a second group of said groups to pass simultaneously with allowing said single signal of said first group to pass.

43. The system of claim 42, wherein said sampling means comprises:

means for combining signals of said first group of said groups, wherein a single signal path is provided from said combining means to said determining means.