Transmitter system and method of operation therefor

• US 6,157,681 A
• Filed: 04/06/1998
• Issued: 12/05/2000
• Est. Priority Date: 04/06/1998
• Status: Expired due to Term

• Current Assignee: CDC Propriete Intellectuelle
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Peterson, Kenneth Maynard, Daniel, Brian Michael, Schmidt, William George
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): PARK, ALBERT C
• Application Number:
  US09/055,395
• Time in Patent Office: 974 Days
• Field of Search: 375/299, 375/298, 375/267, 375/268, 375/279, 375/260, 375/261, 375/300, 375/302, 375/308, 455/101, 455/102, 455/103, 455/42, 455/500
• US Class Current: 375/298
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H03D 5/00 Circuits for demodulating amplitude-modulated or angle-modulated oscillations at will H03D9/00, H03D11/00 take precedence
• CPC Class Codes: H04L 27/18 Phase-modulated carrier systems, i.e. using phase-shift keying H04L27/32 takes precedence
• CPC Class Codes: H04L 27/34 Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems

Abstract

A transmitter system (18) which transmits a communication signal (14) through a phased-array antenna (10) uses a signal processor (26) and a multiplicity of direct modulators (30). Each direct modulator (30) drives a single element (12) of the antenna (10). Each direct modulator (30) receives a digital baseband phase point data signal (62) from a digital data stream (28). The digital data stream (28) also conveys digital beam formation data (60). Each direct modulator (30) digitally combines the baseband phase point data (62) with the beam formation data (60) to produce digital streams that modulate an RF carrier signal (34). The digital data stream (28) is generated by a phased-array signal processor (26) which processes user data bits (86) received from any number of input signals (22) and processes beam signals (24). In one embodiment, the signal processor (26) calculates phase point data (62) representative of all input signals (22).

Claims

1. A transmitter system for transmitting a communication signal through an antenna array, said system comprising:

a signal processing computer configured to receive an input signal and to generate a data stream that conveys phase and amplitude values which are responsive to said input signal, wherein said signal processing computer is configured so that said phase values describe phase point phase modulation values and beam formation phase offset values;

a plurality of direct modulators, wherein each of said direct modulators is adapted to receive a radio frequency (RF) carrier signal, is coupled to said signal processing computer to receive said data stream, and generates a communication signal component that exhibits a frequency substantially equivalent to a frequency of said RF carrier signal, a phase which is responsive to said phase values, and an amplitude which is responsive to said amplitude values; and

a plurality of antenna elements arranged so that each direct modulator couples to one of said antenna elements and so that said communication signal components generated by said direct modulators are simultaneously transmitted from said antenna elements and collectively form said communication signal.

2. A transmitter system as claimed in claim 1 wherein said signal processing computer is further configured so that said amplitude values describe phase point amplitude modulation values and beam formation amplitude offset values.

3. A transmitter system as claimed in claim 1 wherein

said signal processing computer is configured so that, for each of said direct modulators, said phase point phase modulation values are updated more frequently than said beam formation phase offset values.

4. A transmitter system as claimed in claim 1 wherein said direct modulators and said signal processing computer are mutually configured so that each direct modulator is responsive to substantially all of said phase point phase modulation values generated by said signal processing computer and to only a portion of said beam formation phase offset values.

5. A transmitter system as claimed in claim 1 wherein said direct modulators and said signal processing computer are mutually configured so that different direct modulators receive different beam formation phase offset values.

6. A transmitter system as claimed in claim 1 wherein said signal processing computer is further configured to receive a plurality of input signals corresponding to a plurality of channels and to compute said phase point phase modulation values in response to each of said plurality of input signals.

7. A transmitter system as claimed in claim 6 wherein:

said input signals are digital signals which supply user data bits;

said apparatus transmits said communication signal over a stream of unit intervals in which a predetermined number of said user data bits from each of said input signals is transmitted during each unit interval in said stream of unit intervals;

for each of said input signals, said signal processing computer is configured to translate, during one of said unit intervals, said predetermined number of said user input bits into phase point data; and

said signal processing computer is further configured to combine, during one of said unit intervals, said phase point data translated from all of said input signals into an aggregate phase point, said aggregate phase point describing said phase point phase modulation value and a phase point amplitude modulation value.

8. A transmitter system for transmitting a communication signal through an antenna array, said system comprising:

a signal processing computer configured to receive an input signal and to generate a data stream that conveys phase and amplitude values which are responsive to said input signal;

a plurality of direct modulators, wherein each of said direct modulators is adapted to receive a radio frequency (RF) carrier signal, is coupled to said signal processing computer to receive said data stream, and generates a communication signal component that exhibits a frequency substantially equivalent to a frequency of said RF carrier signal, a phase which is responsive to said phase values, and an amplitude which is responsive to said amplitude values, said direct modulators further comprising;

a first register adapted to receive said data stream and configured to hold beam formation phase offset values;

a second register adapted to receive said data stream and configured to hold phase point phase modulation values;

a combination circuit coupled to said first and second registers and configured to generate a stream of element-specific phase values; and

a modulator configured to modulate a phase parameter of said RF carrier signal in response to said stream of element-specific phase values; and

a plurality of antenna elements arranged so that each direct modulator couples to one of said antenna elements and so that said communication signal components generated by said direct modulators are simultaneously transmitted from said antenna elements and collectively form said communication signal.

9. A transmitter system as claimed in claim 8 wherein said modulator is an amplitude-phase modulator which modulates an amplitude parameter of said RF carrier in response to a stream of element-specific amplitude values, and each of said direct modulators additionally comprises:

a third register adapted to receive said data stream and configured to hold beam formation amplitude offset values;

a fourth register adapted to receive said data stream and configured to hold phase point amplitude modulation values; and

a combination circuit coupled to said third and fourth registers and configured to generate said stream of element-specific amplitude values.

10. A transmitter system as claimed in claim 8 wherein each of said direct modulators additionally comprises a frame controller adapted to receive said data stream and being coupled to said first register, said frame controller being configured to identify occurrences of said beam formation phase offset values in said data stream.

11. A method of transmitting a communication signal through an antenna array, said method comprising the steps of:

generating a data stream that conveys phase and amplitude values, said data stream being responsive to an input signal, wherein said generating step comprises the step of configuring said phase values to describe phase point phase modulation values and beam formation phase offset values;

routing said data stream to each of a plurality of direct modulators;

routing an RF carrier signal to each of said direct modulators;

independently modulating said RF carrier signal at each of said direct modulators so that each direct modulator generates a communication signal component that exhibits a frequency substantially equivalent to a frequency of said RF carrier signal, a phase which is responsive to said phase values, and an amplitude which is responsive to said amplitude values; and

radiating said communication signal components generated by said direct modulators to collectively form said communication signal.

12. A method as claimed in claim 11 wherein said generating step comprises the step of configuring said amplitude values to describe phase point amplitude modulation values and beam formation amplitude offset values.

13. A method as claimed in claim 11 wherein:

each direct modulator is responsive to substantially all of said phase point phase modulation values and to only a portion of said beam formation phase offset values; and

different direct modulators receive different beam formation phase offset values.

14. A method as claimed in claim 11 wherein said generating step comprises the step of processing a plurality of input signals so that said phase point phase modulation values are computed in response to each of said plurality of input signals.

15. A method as claimed in claim 14 wherein:

said input signals are digital signals which supply user data bits;

said method transmits said communication signal over a stream of unit intervals in which a predetermined number of said user data bits from each of said input signals is transmitted during each unit interval in said stream of unit intervals;

said generating step comprises the step of translating, for each of said input signals, said predetermined number of said user input bits into phase point data, said translating step occurring during one of said unit intervals; and

said generating step further comprises the step of combining, during one of said unit intervals, said phase point data translated from all of said input signals into an aggregate phase point, said aggregate phase point describing said phase point phase modulation value and a phase point amplitude modulation value.

16. A method of transmitting a communication signal through an antenna array, said method comprising the steps of:

generating a data stream that conveys phase and amplitude values, said data stream being responsive to an input signal;

routing said data stream to each of a plurality of direct modulators;

routing an RF carrier signal to each of said direct modulators;

independently modulating said RF carrier signal at each of said direct modulators so that each direct modulator generates a communication signal component that exhibits a frequency substantially equivalent to a frequency of said RF carrier signal, a phase which is responsive to said phase values, and an amplitude which is responsive to said amplitude values, wherein said independently modulating step further comprises, for each of said direct modulators, the steps of;

obtaining beam formation phase offset values from said phase values of said data stream;

obtaining phase point phase modulation values from said phase values of said data stream;

combining said beam formation phase offset values and said phase point phase modulation values to generate a stream of element-specific phase values; and

varying a phase parameter of said RF carrier signal in response to said stream of element-specific phase values; and

radiating said communication signal components generated by said direct modulators to collectively form said communication signal.

17. A transmitter system for transmitting a communication signal through an antenna array, said system comprising:

a signal processing computer configured to receive a plurality of input signals and to generate a data stream that conveys phase point phase modulation values, beam formation phase offset values, phase point amplitude modulation values, and beam formation amplitude offset values that are collectively responsive to said input signals;

a plurality of direct modulators each of which are coupled to said signal processing computer and each of which comprises;

a first register configured to hold a portion of said beam formation phase offset values, a second register configured to hold said phase point phase modulation values, a third register configured to hold a portion of said beam formation amplitude offset values, and a fourth register configured to hold said phase point amplitude modulation values,

a phase combination circuit coupled to said first and second registers and configured to generate a stream of element-specific phase values, and an amplitude combination circuit coupled to said third and fourth registers and configured to generate a stream of element-specific amplitude values, and

a modulator configured to generate a communication signal component by receiving an RF carrier signal, modulating a phase parameter of said RF carrier signal in response to said stream of element-specific phase values and modulating an amplitude parameter of said RF carrier signal in response to said stream of element-specific amplitude values; and

a plurality of antenna elements arranged so that each direct modulator couples to one of said antenna elements and so that said communication signal components generated by said direct modulators are simultaneously transmitted from said antenna elements and collectively form said communication signal.

18. A transmitter system as claimed in claim 17 wherein:

said input signals are digital signals which supply user data bits;

said apparatus transmits said communication signal over a stream of unit intervals in which a predetermined number of said user data bits from each of said input signals is transmitted during each unit interval in said stream of unit intervals;

for each of said input signals, said signal processing computer is configured to translate, during one of said unit intervals, said predetermined number of said user input bits into phase point data; and

said signal processing computer is further configured to combine, during one of said unit intervals, said phase point data translated from all of said input signals into an aggregate phase point, said aggregate phase point describing one of said phase point phase modulation values and one of said phase point amplitude modulation values.