Multiformat auto-handoff communications handset

• US 5,649,308 A
• Filed: 11/02/1995
• Issued: 07/15/1997
• Est. Priority Date: 04/12/1993
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Andrews, Scott
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/556,863
• Time in Patent Office: 621 Days
• Field of Search: 455/33.2, 455/33.3, 455/33.4, 455/34.1, 455/34.2, 455/54.1, 455/56.1, 455/89, 455/84, 379/60
• US Class Current: 370/334
• CPC Class Codes: H01Q 1/242 specially adapted for hand-held use
• CPC Class Codes: H01Q 21/30 Combinations of separate antenna units operating in different wavebands and connected to a common feeder system
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

Disclosed is an apparatus and method for supporting communications and handoffs between multiple signal formats at multiple carrier frequencies. Antenna circuitry which includes a linearly polarized antenna and a circularly polarized antenna is utilized to receive and transmit the multiple signal formats at the multiple carrier frequencies simultaneously. A pair of RF signal paths each including RF transmit circuitry, RF receive circuitry and RF processing capabilities are utilized to support simultaneous communications between two signal formats. A multisystem controller in communications with each RF signal path initiates and completes handoffs between the multiple signal formats utilizing both RF signal paths to achieve uninterrupted communications across a large service coverage area.

Claims

1. A multiformat auto-handoff communications handset to support communications and handoffs between multiple signal formats at multiple carrier frequencies, said multiformat auto-handoff communications handset comprising:

antenna means for receiving and transmitting the multiple signal formats at the multiple carrier frequencies, said antenna means for simultaneously receiving a first RF receive signal and a second RF receive signal and for simultaneously transmitting a first RF transmit signal and a second RF transmit signal;

first broadband RF receive means for down converting the first RF receive signal into a first IF receive signal, said first broadband RF receive means including a first quadrature LO generator operable to produce a first pair of quadrature signals substantially 90°

out of phase of each other over a frequency range of between about 800 MHz to 2.4 GHz, first broadband RF transmit means for up converting a first IF transmit signal into the first RF transmit signal, and first IF processor means for demodulating multiple signal formats of the first IF receive signal and for modulating multiple signal formats of the first IF transmit signal;

second broadband RF receive means for down converting the second RF receive signal into a second IF receive signal, said second broadband RF receive means including a second quadrature LO generator operable to produce a second pair of quadrature signals substantially 90°

out of phase of each other over a frequency range of between about 800 MHz to 2.4 GHz, second broadband RF transmit means for up converting a second IF transmit signal into the second RF transmit signal, and second IF processor means for demodulating multiple signal formats of the second IF receive signal and for modulating multiple signal formats of the second IF transmit signal; and

multisystem controller means for initiating and completing handoffs between the multiple signal formats at the multiple carrier frequencies.

2. The multiformat auto-handoff communications handset as defined in claim 1 wherein the antenna means includes a linearly polarized antenna and a circularly polarized antenna, said linearly polarized antenna and said circularly polarized antenna each operable to receive one of either the first RF receive signal or the second RF receive signal and each operable to transmit one of either the first RF transmit signal or the second RF transmit signal.

3. The multiformat auto-handoff communications handset as defined in claim 2 further comprising a bidirectional broadband duplexor/multiplexor, a broadband low noise pre-amp, a power divider, a power combiner and a broadband power amp, said bidirectional broadband duplexor/multiplexor operable to combine the first RF receive signal and the second RF receive signal into a combined RF receive signal, said broadband low noise pre-amp operable to amplify the combined RF receive signal, said power divider operable to split the combined RF receive signal, said power combiner operable to combine the first RF transmit signal from the first RF transmit means and the second RF transmit signal from the second RF transmit means into a combined RF transmit signal, said broadband power amp operable to amplify the combined RF transmit signal and said bidirectional broadband duplexor/multiplexor further operable to split the combined RF transmit signal and apply the first RF transmit signal and the second RF transmit signal to one of either the linearly polarized antenna or the circularly polarized antenna.

4. The multiformat auto-handoff communications handset as defined in claim 2 further comprising a bidirectional broadband duplexor/multiplexor, a broadband low noise pre-amp, a power divider, a first power amp, and a second power amp, said bidirectional broadband duplexor/multiplexor operable to combine the first RF receive signal and the second RF receive signal into a combined RF receive signal, said broadband low noise pre-amp operable to amplify the combined RF receive signal, said power divider operable to split the combined RF receive signal, said first power amp operable to amplify the first RF transmit signal from the first RF transmit means, said second power amp operable to amplify the second RF transmit signal from the second RF transmit means and said bidirectional broadband duplexor/multiplexor further operable to apply the first RF transmit signal and the second RF transmit signal to one of either the linearly polarized antenna or the circularly polarized antenna.

5. The multiformat auto-handoff communications handset as defined in claim 1 wherein the first RF receive means includes a first dual ortho broadband image reject mixer and the second RF receive means includes a second dual ortho broadband image reject mixer, said first dual ortho broadband image reject mixer operable to convert the first RF receive signal into the first IF receive signal, said second dual ortho broadband image reject mixer operable to convert the second RF receive signal into the second IF receive signal.

6. The multiformat auto-handoff communications handset as defined in claim 5 wherein the first RF receive means further includes a first phase lock loop and the second RF receive means further includes a second phase lock loop, said first phase lock loop operable to produce a first tuning signal to adjust the tuning of the first quadrature LO generator, said second phase lock loop operable to produce a second tuning signal to adjust the tuning of the second quadrature LO generator.

7. The multiformat auto-handoff communications handset as defined in claim 6 wherein the first RF receive means further includes a plurality of first switchable bandpass filters and the second RF receive means further includes a plurality of second switchable bandpass filters, said first plurality of switchable bandpass filter operable to band limit the first IF receive signal from the first dual ortho broadband image reject mixer, said second plurality of switchable bandpass filters operable to band limit the second IF receive signal from the second dual ortho broadband image reject mixer.

8. The multiformat auto-handoff communications handset as defined in claim 6 wherein the first quadrature LO generator includes a first divide by one/divide by two circuit and the second quadrature LO generator includes a second divide by one/divide by two circuit, said first divide by one/divide by two circuit operable to divide the first tuning signal by one of either one or two, said second divide by one/divide by two circuit operable to divide the second tuning signal by one of either one or two.

9. The multiformat auto-handoff communications handset as defined in claim 5 wherein the first dual ortho broadband image reject mixer includes a first 0°

power divider, a first in phase mixer, a first quadrature mixer, a first adjustable in phase amp and a first adjustable quadrature amp and the second dual ortho broadband image reject mixer includes a second 0°

power divider, a second in phase mixer, a second quadrature mixer, a second adjustable in phase amp and a second adjustable quadrature amp, said first 0°

power divider operable to split the first RF receive signal into a first upper RF receive signal and a first lower RF receive signal, said first in phase mixer operable to mix the first upper RF receive signal with the first in phase signal, said first quadrature mixer operable to mix the first lower RF receive signal with the first quadrature signal, said first adjustable in phase amp operable to amplify the product of the first upper RF receive signal and the first in phase signal and said first adjustable quadrature amp operable to amplify the product of the first lower RF receive signal and the first quadrature signal, said second 0°

power divider operable to split the power of the second RF receive signal into a second upper RF receive signal and a second lower RF receive signal, said second in phase mixer operable to mix the second upper RF receive signal with the second in phase signal, said second quadrature mixer operable to mix the second lower RF receive signal with the second quadrature signal, said second adjustable in phase amp operable to amplify the product of the second upper RF receive signal and the second in phase signal and said second adjustable quadrature amp operable to amplify the product of the second lower RF receive signal and the second quadrature signal.

10. The multiformat auto-handoff communications handset as defined in claim 9 wherein the first dual ortho broadband image reject mixer further includes a first 90°

coupler and the second dual ortho broadband image reject mixer further includes a second 90°

coupler, said first 90°

coupler operable to add 90°

to the product of the first upper RF receive signal and the first in phase signal and operable to sum it with the product of the first lower RF receive signal and the first quadrature signal, said second 90°

coupler operable to add 90°

to the product of the second upper RF receive signal and the second in phase signal and operable to sum it with the product of the second lower RF receive signal and the second quadrature signal.

11. The multiformat auto-handoff communications handset as defined in claim 8 wherein the first divide by one/divide by two circuit is in electrical connection with a first quadrature branch having a first inverter and a first divide by two circuit and a first in phase branch having a second divide by two circuit and the second divide by one/divide by two circuit is in electrical connection with a second quadrature branch having a second inverter and a third divide by two circuit and a second in phase branch having a fourth divide by two circuit, said first quadrature branch operable to invert the first tuning signal and divide the first tuning signal by two, said first in phase branch operable to divide the first tuning signal by two, said second quadrature branch operable to invert the second tuning signal and divide the second tuning signal by two, said second in phase branch operable to divide the second tuning signal by two.

12. The multiformat auto-handoff communications handset as defined in claim 1 wherein the first RF transmit means includes a first broadband single sideband modulator and the second RF transmit means includes a second broadband single sideband modulator, said first broadband single sideband modulator operable to convert the first IF transmit signal into the first RF transmit signal, said second broadband single sideband modulator operable to convert the second IF transmit signal into the second RF transmit signal.

13. The multiformat auto-handoff communications handset as defined in claim 12 wherein the first RF transmit means further includes a first quadrature LO generator and the second RF transmit means further includes a second quadrature LO generator, said first quadrature LO generator operable to produce a first pair of quadrature signals substantially 90°

out of phase of each other over a frequency range of between about 800 MHz to 2.4 GHz, said first pair of quadrature signals including a first in phase signal and a first quadrature signal, said second quadrature LO generator operable to produce a second pair of quadrature signals substantially 90°

out of phase of each other over a frequency range of between about 800 MHz to 2.4 GHz, said second pair of quadrature signals including a second in phase signal and a second quadrature signal.

14. The multiformat auto-handoff communications handset as defined in claim 13 wherein the first broadband single sideband modulator includes a first 90°

coupler, a first in phase mixer, a first quadrature mixer, a first adjustable in phase amp, a first adjustable quadrature amp and a first 0°

power combiner and the second single side band modulator includes a second 90°

coupler, a second in phase mixer, a second quadrature mixer, a second adjustable in phase amp, a second adjustable quadrature amp and a second 0°

power combiner, said first 90°

coupler operable to produce a first pair of IF transmit quadrature signals substantially 90°

out of phase of each other, said first pair of IF transmit quadrature signals including a first IF transmit in phase signal and a first IF transmit quadrature signal, said first in phase mixer operable to mix the first IF transmit quadrature signal with the first in phase signal, said first quadrature mixer operable to mix the first IF transmit in phase signal with the first quadrature signal, said first adjustable in phase amp operable to amplify the product of the first IF transmit quadrature signal and the first in phase signal, said first adjustable quadrature amp operable to amplify the product of the first IF transmit in phase signal and the first quadrature signal and said first 0°

power combiner operable to combine the product of the first IF transmit quadrature signal and the first in phase signal with the product of the first IF transmit in phase signal and the first quadrature signal, said second 90°

coupler operable to produce a second pair of IF transmit quadrature signals substantially 90°

out of phase of each other, said second pair of IF transmit quadrature signals including a second IF transmit in phase signal and a second IF transmit quadrature signal, said second in phase mixer operable to mix the second IF transmit quadrature signal with the second in phase signal, said second quadrature mixer operable to mix the second IF transmit in phase signal with the second quadrature signal, said second adjustable in phase amp operable to amplify the product of the second IF transmit quadrature signal and the second in phase signal, said second adjustable quadrature amp operable to amplify the product of the second IF transmit in phase signal and the second quadrature signal and said second 0°

power combiner operable to combine the product of the second IF transmit quadrature signal and the second in phase signal with the product of the second IF transmit in phase signal and the second quadrature signal.

15. The multiformat auto-handoff communications handset as defined in claim 13 wherein the first RF transmit means further includes a first phase lock loop and the second RF transmit means further includes a second phase lock loop, said first phase lock loop operable to produce a first tuning signal to adjust the tuning of the first quadrature LO generator, said second phase lock loop operable to produce a second tuning signal to adjust the tuning of the second quadrature LO generator.

16. The multiformat auto hand-off communications handset as defined in claim 15 wherein the first quadrature LO generator includes a first divide by one/divide by two circuit and the second quadrature LO generator includes a second divide by one/divide by two circuit, said first divide by one/divide by two circuit operable to divide the first tuning signal by one of either one or two, said second divide by one/divide by two circuit operable to divide the second tuning signal by one of either one or two.

17. The multiformat auto-handoff communications handset as defined in claim 15 wherein the first RF transmit means further includes a first bandpass filter and the second RF transmit means further includes a second bandpass filter, said first bandpass filter operable to band limit the first IF transmit signal from the first IF processor means, said second bandpass filter operable to band limit the second IF transmit signal from the second IF processor means.

18. The multiformat auto-handoff communications handset as defined in claim 17 wherein the first RF transmit means further includes a plurality of first switchable bandpass filters and the second RF transmit means further includes a plurality of second switchable bandpass filters, said plurality of first switchable bandpass filters operable to band limit the first RF transmit signal from the first broadband single sideband modulator, said plurality of second switchable bandpass filters operable to band limit the second RF transmit signal from the second broadband single sideband modulator.

19. The multiformat auto-handoff communications handset as defined in claim 16 wherein the first divide by one/divide by two circuit is in electrical connection with a first quadrature branch having a first inverter and a first divide by two circuit and a first in phase branch having a second divide by two circuit and the second divide by one/divide by two circuit is in electrical connection with a second quadrature branch having a second inverter and a third divide by two circuit and a second in phase branch having a fourth divide by two circuit, said first quadrature branch operable to invert the first tuning signal and divide the first tuning signal by two, said first in phase branch operable to divide the first tuning signal by two, said second quadrature branch operable to invert the second tuning signal and divide the second tuning signal by two, said second in phase branch operable to divide the second tuning signal by two.

20. The multiformat auto-handoff communications handset as defined in claim 1 wherein the first IF processor means includes a first digital IF/baseband processor controller and the second IF processor means includes a second digital IF/baseband processor controller, said first digital IF/baseband processor controller operable to demodulate multiple signal formats of the first IF receive signal to extract voice and operating data and operable to modulate voice and operating data into multiple signal formats of the first IF transmit signal, said second digital IF/baseband processor controller operable to demodulate multiple signal formats of the second IF receive signal to extract voice and operating data and operable to modulate voice and operating data into multiple signal formats of the second IF transmit signal.

21. The multiformat auto-handoff communications handset as defined in claim 20 wherein the first digital IF/baseband processor controller is operable to receive the first IF receive signal and transmit the first IF transmit signal at a multiple signal format selected from the group consisting of AMPS, IS-54, PCN, DECT, GSM, FDM, TDMA and CDMA and the second digital IF/baseband processor controller is operable to receive the second IF receive signal and transmit the second IF transmit signal at a multiple signal format selected from the group consisting of AMPS, IS-54, PCN, DECT, GSM, FDM, TDMA and CDMA.

22. The multiformat auto-handoff communications handset as defined in claim 1 wherein the multisystem controller means includes a multisystem controller, said multisystem controller in electrical communication with the first broadband RF receive means, the first broadband RF transmit means, the first IF processor means, the second broadband RF receive means, the second broadband RF transmit means and the second IF processor means.

23. The multiformat auto-handoff communications handset as defined in claim 22 wherein the multisystem controller contains a program hierarchy to enable the multisystem controller to select a signal format selected from the group consisting of AMPS, IS-54, PCN, DECT, GSM, FDM, TDMA and CDMA.

24. The multiformat auto-handoff communications handset as defined in claim 22 wherein the multisystem controller is further operable to monitor the power level of the first RF receive signal and direct the second RF transmit means to issue an order wire to initiate a handoff between a currently operating signal format and signal frequency to an available signal format and signal frequency.

25. The multiformat auto-handoff communications handset as defined in claim 22 wherein the multisystem controller is further operable to monitor the power level of the second RF receive signal and direct the first RF transmit means to issue an order wire to initiate a handoff between a currently operating signal format and signal frequency to an available signal format and signal frequency.

26. A multiformat auto-handoff communications handset to support communications and hand-offs between multiple signal formats at multiple carrier frequencies, said multiformat auto-handoff communications handset comprising:

antenna means for receiving and transmitting the multiple signal formats at the multiple carrier frequencies, said antenna means for simultaneously receiving a first RF receive signal and a second RF receive signal and for simultaneously transmitting a first RF transmit signal and a second RF transmit signal;

a first RF signal path, said first RF signal path including a first RF receive system for down converting the first RF receive signal into a first IF receive signal, a first RF transmit system for up converting a first IF transmit signal into the first RF transmit signal and a first digital IF/baseband processor controller for demodulating multiple signal formats of the first IF receive signal and for modulating multiple signal formats of the first IF transmit signal, said first RF transmit system including a first quadrature LO generator operable to produce a first pair of quadrature signals substantially 90°

out of phase of each other over a frequency range of between about 800 MHz to 2.4 GHz;

a second RF signal path, said second RF signal path including a second RF receive system for down converting the second RF receive signal into a second IF receive signal, a second RF transmit system for up converting a second IF transmit signal into the second RF transmit signal and a second digital IF/baseband processor controller for demodulating multiple signal formats of the second IF receive signal and for modulating multiple signal formats of the second IF transmit signal, said second RF transmit system including a second quadrature LO generator operable to produce a second pair of quadrature signals substantially 90°

out of phase of each other over a frequency range of between about 800 MHz to 2.4 GHz; and

a multisystem controller for initiating and completing handoffs between the multiple signal formats at the multiple carrier frequencies by utilizing the first RF signal path and the second RF signal path.

27. The multiformat auto-handoff communications handset as defined in claim 26 wherein the first RF receive system includes a first dual ortho broadband image reject mixer to convert the first RF receive signal into the first IF receive signal.

28. The multiformat auto-handoff communications handset as defined in claim 27 wherein the first RF transmit system includes a first broadband single sideband modulator to convert the first IF transmit signal into the first RF transmit signal.

29. The multiformat auto-handoff communications handset as defined in claim 28 wherein the first RF receive system further includes a first quadrature LO generator to produce a first pair of quadrature signals substantially 90°

out of phase of each other over a frequency range of between about 800 MHz to 2.4 GHz and the first RF transmit system further includes a second quadrature LO generator to produce a second pair of quadrature signals substantially 90°

out of phase with each other over a frequency range of between about 800 MHz to 2.4 GHz.

30. The multiformat auto-handoff communications handset as defined in claim 29 wherein the first RF receive system further includes a first phase lock loop to adjust the tuning of the first quadrature LO generator and the first RF transmit system further includes a second phase lock loop to adjust the tuning of the second quadrature LO generator.

31. The multiformat auto-handoff communications handset as defined in claim 30 wherein the first RF signal path is identical to the second RF signal path.

32. The multiformat auto-handoff communications handset as defined in claim 31 wherein the multisystem controller monitors one of either the first RF receive signal in the first RF signal path or the second RF receive signal in the second RF signal path to determine whether to initiate a handoff between a currently operating signal format and signal frequency to an available signal format and signal frequency.

33. A method of supporting uninterrupted communications and hand-offs between multiple signal formats at multiple carrier frequencies through multiple service coverage areas, said method comprising the steps of:

providing a first antenna and a second antenna for receiving and transmitting the multiple signal formats at the multiple carrier frequencies in the multiple service coverage areas;

receiving a first RF receive signal of a first signal format in a first service coverage area and a second RF receive signal of a second signal format in a second service coverage area from the first antenna and the second antenna;

generating a first pair of quadrature signals substantially 90°

out of phase of each other over a frequency range of between about 800 MHz to 2.4 GHz and down converting the first RF receive signal using said first pair of quadrature signals into a first IF receive signal in a first RF receive system and generating a second pair of quadrature signals substantially 90°

out of phase of each other over a frequency range of between about 800 MHz to 2.4 GHz and down converting the second RF receive signal using said second pair of quadrature signals into a second IF receive signal in a second RF receive system;

demodulating the first IF receive signal in a first digital IF/baseband processor controller and demodulating the second IF receive signal in a second digital IF/baseband processor controller;

modulating a first IF transmit signal in the first digital IF/baseband processor controller and modulating a second IF transmit signal in the second digital IF/baseband processor controller;

up converting the first IF transmit signal into a first RF transmit signal in a first RF transmit system and up converting the second IF transmit signal into a second RF transmit signal in a second RF transmit system;

transmitting the first RF transmit signal of the first signal format in the first service coverage area and the second RF transmit signal of the second signal format in the second service coverage area from the first antenna and second antenna; and

providing a multisystem controller for initiating and completing hand-offs to provide uninterrupted communication between the multiple signal formats at the multiple carrier frequencies through the multiple service coverage areas.

34. The method as defined in claim 33 wherein the step of providing a first antenna and a second antenna includes the steps of providing:

a linearly polarized antenna and a circularly polarized antenna to receive the first RF receive signal and the second RF receive signal and transmit the first RF transmit signal and the second RF transmit signal;

providing a bidirectional broadband duplexor/multiplexor to combine the first RF receive signal and the second RF receive signal into a combined RF receive signal and to separate a combined RF transmit signal into the first RF transmit signal and the second RF transmit signal;

providing a broadband low noise pre-amp to amplify the combined RF receive signal;

providing a power divider to split the combined RF receive signal;

providing a power combiner to combine the first RF transmit signal and the second RF transmit signal into the combined RF transmit signal; and

providing a broadband power amp to amplify the combined RF transmit signal.

35. The method as defined in claim 33 wherein the step of down converting the first RF receive signal and the second RF receive signal include the steps of:

mixing the first RF receive signal with said first pair of quadrature signals in the first RF receive system; and

mixing the second RF receive signal with said second pair of quadrature signals in the second RF receive system.

36. The method as defined in claim 33 wherein the step of demodulating the first IF receive signal and the second IF receive signal include the steps of:

extracting voice and operating data from the first IF receive signal in the first digital IF/baseband processor controller; and

extracting voice and operating data from the second IF receive signal in the second digital IF/baseband processor controller.

37. The method as defined in claim 33 wherein the step of modulating the first IF transmit signal and the second IF transmit signal include the steps of:

modulating voice and operating data into the first IF transmit signal in the first digital IF/baseband processor controller; and

modulating voice and operating data into the second IF transmit signal in the second digital IF/baseband processor controller.

38. The method as defined in claim 33 wherein the step of upconverting the first IF transmit signal and the second IF transmit signal includes the steps of:

mixing a quadrature pair of the first IF transmit signal with a pair of quadrature signals in the first RF transmit system; and

mixing a quadrature pair of the second IF transmit signal with a pair of quadrature signals in the second RF transmit system.

39. The method as defined in claim 33 wherein the step of initiating and completing handoffs between the multiple signal formats at the multiple carrier frequencies includes the steps of:

monitoring the power level of one of either the first RF receive signal or the second RF receive signal with the multisystem controller; and

directing one of either the first RF transmit system or the second RF transmit system to issue an order wire for initiating a handoff between a currently operating signal format and signal frequency to an available signal format and signal frequency.