Multichannel homodyne receiver
-
0Associated
Cases -
0Associated
Defendants -
0Accused
Products -
89Forward
Citations -
0
Petitions -
7
Assignments
First Claim
1. A homodyne radar transmitter/receiver device comprising:
- microwave source means for producing a microwave transmission signal;
a combination transmitter/receiver antenna for transmitting said microwave transmission signal and detecting both modulated and unmodulated backscatter signals;
transmission line means connecting said microwave source and said combination transmitter/receiver antenna;
at least two output connectors attached to said transmission line means at intervals equal to approximately 1/8 wavelength of said microwave transmission signal;
means for detecting attached to said output connectors;
low pass filter means connected to said means for detecting;
signal combiner/amplifier means connected to said low pass filter means for producing a single output containing modulated backscatter information for all phase conditions of said modulated and unmodulated backscatter signals.
7 Assignments
0 Petitions
Accused Products
Abstract
A homodyne radar transmitter/receiver device which produces a single combined output which contains modulated backscatter information for all phase conditions of both modulated and unmodulated backscatter signals. The device utilizes taps along coaxial transmission lines, strip transmission line, and waveguides which are spaced by 1/8 wavelength or 1/6 wavelength, etc. This greatly reduces costs by eliminating separate transmission and reception antennas and an expensive arrangement of power splitters and mixers utilized in the prior art.
93 Citations
View as Search Results
| SYSTEM AND METHOD FOR MEASUREMENT OF DISTANCE TO A TAG BY A MODULATED BACKSCATTER RFID READER | ||
|
Patent #
US 20110187600A1
Filed 07/21/2010
|
Current Assignee
Amtech Systems LLC
|
Sponsoring Entity
Amtech Systems LLC
|
| Mobile terminal circuit including an RFID tag and wireless identification method using the same | ||
|
Patent #
US 7,710,238 B2
Filed 02/12/2004
|
Current Assignee
Samsung Electronics Co. Ltd.
|
Sponsoring Entity
Samsung Electronics Co. Ltd.
|
| Automated vehicle parking system for a plurality of remote parking facilities | ||
|
Patent #
RE41085E1
Filed 04/26/2002
|
Current Assignee
Amtech Systems LLC
|
Sponsoring Entity
TC License Limited
|
| Wireless communications devices, methods of processing a wireless communication signal, wireless communication synchronization methods and a radio frequency identification device communication method | ||
|
Patent #
US 7,760,835 B2
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Wireless communication systems, interfacing devices, communication methods, methods of interfacing with an interrogator, and methods of operating an interrogator | ||
|
Patent #
RE41916E1
Filed 07/16/2004
|
Current Assignee
Round Rock Research LLC
|
Sponsoring Entity
Round Rock Research LLC
|
| Homodyne RFID receiver and method | ||
|
Patent #
US 7,535,360 B2
Filed 04/24/2007
|
Current Assignee
Neology Incorporated
|
Sponsoring Entity
SIRIT TECHNOLOGIES INC. A CORPORATION OF CANADA
|
| Distance/ranging determination using relative phase data | ||
|
Patent #
US 7,580,378 B2
Filed 03/14/2005
|
Current Assignee
RUIZHANG TECHNOLOGY LIMITED COMPANY
|
Sponsoring Entity
Alien Technology Corporation
|
| Homodyne RFID receiver and method | ||
|
Patent #
US 7,366,465 B2
Filed 11/19/2004
|
Current Assignee
3M Innovative Properties Company
|
Sponsoring Entity
SIRIT TECHNOLOGIES INC.
|
| Mobile terminal having smart card coupled with RFID tag and method for performing RFID function in such mobile terminal | ||
|
Patent #
US 7,374,100 B2
Filed 10/21/2004
|
Current Assignee
Samsung Electronics Co. Ltd.
|
Sponsoring Entity
Samsung Electronics Co. Ltd.
|
| Low cost RFID labeling device | ||
|
Patent #
US 7,436,302 B2
Filed 11/21/2005
|
Current Assignee
SUPERVISION LLC
|
Sponsoring Entity
Jessup Steven C.
|
| Low cost RFID labeling device | ||
|
Patent #
US 20070030153A1
Filed 11/21/2005
|
Current Assignee
SUPERVISION LLC
|
Sponsoring Entity
SUPERVISION LLC
|
| Low cost RFID system | ||
|
Patent #
US 20070040681A1
Filed 08/19/2005
|
Current Assignee
SUPERVISION LLC
|
Sponsoring Entity
SUPERVISION LLC
|
| Phase modulation in RF tag | ||
|
Patent #
US 7,180,402 B2
Filed 08/27/2004
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Homodyne RFID receiver and method | ||
|
Patent #
US 7,209,040 B2
Filed 11/19/2004
|
Current Assignee
Neology Incorporated
|
Sponsoring Entity
SIRIT TECHNOLOGIES INC.
|
| Homodyne single mixer receiver and method therefor | ||
|
Patent #
US 7,199,713 B2
Filed 11/19/2004
|
Current Assignee
Neology Incorporated
|
Sponsoring Entity
SIRIT TECHNOLOGIES INC.
|
| HOMODYNE RFID RECEIVER AND METHOD | ||
|
Patent #
US 20070247314A1
Filed 04/24/2007
|
Current Assignee
Neology Incorporated
|
Sponsoring Entity
Neology Incorporated
|
| Low cost RFID system | ||
|
Patent #
US 7,295,118 B2
Filed 08/19/2005
|
Current Assignee
SUPERVISION LLC
|
Sponsoring Entity
ENSYC TECHNOLOGIES
|
| Full-spectrum passive communication system and method | ||
|
Patent #
US 6,970,089 B2
Filed 07/03/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| In-building modulated backscatter system | ||
|
Patent #
US 5,952,922 A
Filed 12/31/1996
|
Current Assignee
Lucent Technologies Inc.
|
Sponsoring Entity
Lucent Technologies Inc.
|
| Antenna array in an RFID system | ||
|
Patent #
US 6,184,841 B1
Filed 12/31/1996
|
Current Assignee
Lucent Technologies Inc.
|
Sponsoring Entity
Lucent Technologies Inc.
|
| Challenged-based tag authentication model | ||
|
Patent #
US 6,842,106 B2
Filed 10/04/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Wireless communications systems, radio frequency identification devices, wireless communications methods, and radio frequency identification device communications methods | ||
|
Patent #
US 7,019,618 B2
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Method of communications in a backscatter system, interrogator, and backscatter communications system | ||
|
Patent #
US 6,169,474 B1
Filed 04/23/1998
|
Current Assignee
Round Rock Research LLC
|
Sponsoring Entity
Micron Technology Inc.
|
| Encryption for modulated backscatter systems | ||
|
Patent #
US 6,130,623 A
Filed 12/31/1996
|
Current Assignee
Lucent Technologies Inc.
|
Sponsoring Entity
Lucent Technologies Inc.
|
| QPSK modulated backscatter system | ||
|
Patent #
US 6,456,668 B1
Filed 12/31/1996
|
Current Assignee
Lucent Technologies Inc.
|
Sponsoring Entity
Lucent Technologies Inc.
|
| Multi-frequency communication system and method | ||
|
Patent #
US 6,745,008 B1
Filed 06/06/2000
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Modulated backscatter location system | ||
|
Patent #
US 6,046,683 A
Filed 12/31/1996
|
Current Assignee
LGS Innovations LLC
|
Sponsoring Entity
Lucent Technologies Inc.
|
| System and method for communicating with an RFID transponder with reduced noise and interference | ||
|
Patent #
US 6,639,509 B1
Filed 09/07/1999
|
Current Assignee
Intermec IP Corporation
|
Sponsoring Entity
Intermec IP Corporation
|
| System and method to identify multiple RFID tags | ||
|
Patent #
US 7,009,495 B2
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Wireless security system | ||
|
Patent #
US 6,369,710 B1
Filed 03/27/2000
|
Current Assignee
Lucent Technologies Inc.
|
Sponsoring Entity
Lucent Technologies Inc.
|
| Inexpensive modulated backscatter reflector | ||
|
Patent #
US 6,243,012 B1
Filed 12/31/1996
|
Current Assignee
Lucent Technologies Inc.
|
Sponsoring Entity
Lucent Technologies Inc.
|
| RFID system and method including tag ID compression | ||
|
Patent #
US 7,009,526 B2
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Radio frequency identification devices, backscatter communication device wake-up methods, communication device wake-up methods and a radio frequency identification device wake-up method | ||
|
Patent #
US 7,019,617 B2
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Method of communications in a backscatter system, interrogator, and backscatter communications system | ||
|
Patent #
US 6,229,987 B1
Filed 04/26/2000
|
Current Assignee
Round Rock Research LLC
|
Sponsoring Entity
Micron Technology Inc.
|
| IQ combiner technology in modulated backscatter system | ||
|
Patent #
US 5,784,686 A
Filed 12/31/1996
|
Current Assignee
Lucent Technologies Inc.
|
Sponsoring Entity
Lucent Technologies Inc.
|
| Long-range, full-duplex, modulated-reflector cell phone for voice/data transmission | ||
|
Patent #
US 6,434,372 B1
Filed 01/12/2001
|
Current Assignee
TRIAD National Security LLC
|
Sponsoring Entity
Regents of the University of California
|
| Method and system for data communication between a read/write device and a mobile memory device based on transfer-time measurement | ||
|
Patent #
US 7,016,647 B2
Filed 06/10/2002
|
Current Assignee
Siemens AG
|
Sponsoring Entity
Siemens AG
|
| Self-synchronous spread spectrum transmitter/receiver | ||
|
Patent #
US 4,912,722 A
Filed 09/20/1988
|
Current Assignee
Alcatel-Lucent USA Inc.
|
Sponsoring Entity
Bell Telephone Laboratories Inc., American Telephone Telegraph
|
| Enhanced uplink modulated backscatter system | ||
|
Patent #
US 5,940,006 A
Filed 12/12/1995
|
Current Assignee
ATT Inc.
|
Sponsoring Entity
-
|
| Method of communications in a backscatter system, interrogator, and backscatter communications system | ||
|
Patent #
US 6,075,973 A
Filed 05/18/1998
|
Current Assignee
Round Rock Research LLC
|
Sponsoring Entity
Micron Technology Inc.
|
| Wireless communication systems, radio frequency identification devices, methods of enhancing a communications range of a radio frequency identification device, and wireless communication methods | ||
|
Patent #
US 6,914,528 B2
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Dual mode modulated backscatter system | ||
|
Patent #
US 5,649,295 A
Filed 06/19/1995
|
Current Assignee
Lucent Technologies Inc.
|
Sponsoring Entity
Lucent Technologies Inc.
|
| Full duplex modulated backscatter system | ||
|
Patent #
US 5,649,296 A
Filed 06/19/1995
|
Current Assignee
Lucent Technologies Inc.
|
Sponsoring Entity
Lucent Technologies Inc.
|
| Wireless communication systems, interfacing devices, communication methods, methods of interfacing with an interrogator, and methods of operating an interrogator | ||
|
Patent #
US 6,420,961 B1
Filed 05/14/1998
|
Current Assignee
Round Rock Research LLC
|
Sponsoring Entity
Micron Technology Inc.
|
| Method of simultaneously reading multiple radio frequency tags, RF tags, and RF reader | ||
|
Patent #
US 6,995,655 B2
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Distance/ranging by determination of RF phase delta | ||
|
Patent #
US 6,868,073 B1
Filed 06/06/2000
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Multi-level RF identification system | ||
|
Patent #
US 6,765,476 B2
Filed 03/09/2001
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Homodyne RFID receiver and method | ||
|
Patent #
US 20060109128A1
Filed 11/19/2004
|
Current Assignee
Neology Incorporated
|
Sponsoring Entity
Neology Incorporated
|
| Backscatter communication device wake-up methods, communication device wake-up methods, and radio frequency identification device wake-up methods | ||
|
Patent #
US 20060100001A1
Filed 12/14/2005
|
Current Assignee
Michael A. Hughes, Richard M. Pratt
|
Sponsoring Entity
Michael A. Hughes, Richard M. Pratt
|
| Homodyne single mixer receiver and method therefor | ||
|
Patent #
US 20060109127A1
Filed 11/19/2004
|
Current Assignee
Neology Incorporated
|
Sponsoring Entity
Neology Incorporated
|
| Homodyne RFID receiver and method | ||
|
Patent #
US 20060111051A1
Filed 11/19/2004
|
Current Assignee
3M Innovative Properties Company
|
Sponsoring Entity
3M Innovative Properties Company
|
| Phase modulation in RF tag | ||
|
Patent #
US 20050083179A1
Filed 08/27/2004
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Mobile communication terminal with RFID function and RFID programming method in the same | ||
|
Patent #
US 20050088285A1
Filed 04/27/2004
|
Current Assignee
Samsung Electronics Co. Ltd.
|
Sponsoring Entity
Samsung Electronics Co. Ltd.
|
| Mobile terminal circuit including an RFID tag and wireless identification method using the same | ||
|
Patent #
US 20050075079A1
Filed 02/12/2004
|
Current Assignee
Samsung Electronics Co. Ltd.
|
Sponsoring Entity
Samsung Electronics Co. Ltd.
|
| Mobile terminal having smart card coupled with RFID tag and method for performing RFID function in such mobile terminal | ||
|
Patent #
US 20050116050A1
Filed 10/21/2004
|
Current Assignee
Samsung Electronics Co. Ltd.
|
Sponsoring Entity
Samsung Electronics Co. Ltd.
|
| Distance/ranging determination using relative phase data | ||
|
Patent #
US 20050237953A1
Filed 03/14/2005
|
Current Assignee
RUIZHANG TECHNOLOGY LIMITED COMPANY
|
Sponsoring Entity
RUIZHANG TECHNOLOGY LIMITED COMPANY
|
| Radio frequency indentification device communications systems, wireless communication devices, wireless communication systems, backscatter communication methods, radio frequency identification device communication methods and a radio frequency identification device | ||
|
Patent #
US 20040066752A1
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| RFID system and method including tag ID compression | ||
|
Patent #
US 20040066279A1
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| System and method to identify multiple RFID tags | ||
|
Patent #
US 20040066281A1
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Method of simultaneously reading multiple radio frequency tags, RF tags, and RF reader | ||
|
Patent #
US 20040198222A1
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
-
|
| Radio frequency identification devices, backscatter communication device wake-up methods, communication device wake-up methods and a radio frequency identification device wake-up method | ||
|
Patent #
US 20040198233A1
Filed 10/02/2002
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| Method and system for transferring data between at least one read/write device and at least one data memory in an identification system using transfer-time measurement for selecting received data | ||
|
Patent #
US 20030020598A1
Filed 06/10/2002
|
Current Assignee
Siemens AG
|
Sponsoring Entity
Siemens AG
|
| Single-pass guaranteed-fit data compression using rate feedback | ||
|
Patent #
US 20030081845A1
Filed 11/01/2001
|
Current Assignee
Hewlett-Packard Development Company L.P.
|
Sponsoring Entity
Hewlett-Packard Development Company L.P.
|
| Radio frequency identification transponder having a reflector | ||
|
Patent #
US 6,441,740 B1
Filed 02/27/1999
|
Current Assignee
Intermec IP Corporation
|
Sponsoring Entity
Intermec IP Corporation
|
| Automated vehicle parking system for a plurality of remote parking facilities | ||
|
Patent #
RE37822E1
Filed 04/06/2000
|
Current Assignee
Amtech Systems LLC
|
Sponsoring Entity
TC License Limited
|
| Distributed impedance matching circuit for high reflection coefficient load | ||
|
Patent #
US 6,177,872 B1
Filed 11/13/1998
|
Current Assignee
Intermec IP Corporation
|
Sponsoring Entity
Intermec IP Corporation
|
| Magnetic tape storage media having RFID transponders | ||
|
Patent #
US 6,201,474 B1
Filed 11/18/1998
|
Current Assignee
Intermec IP Corporation
|
Sponsoring Entity
Intermec IP Corporation
|
| Method and apparatus for wireless radio frequency testing of RFID integrated circuits | ||
|
Patent #
US 6,236,223 B1
Filed 02/10/1999
|
Current Assignee
Intermec IP Corporation
|
Sponsoring Entity
Intermec IP Corporation
|
| RFID integrated in electronic assets | ||
|
Patent #
US 6,249,227 B1
Filed 11/04/1998
|
Current Assignee
Intermec IP Corporation
|
Sponsoring Entity
Intermec IP Corporation
|
| Radio frequency transponder with improved read distance | ||
|
Patent #
US 6,281,794 B1
Filed 05/25/1999
|
Current Assignee
Intermec IP Corporation
|
Sponsoring Entity
Intermec IP Corporation
|
| Radio frequency identification system | ||
|
Patent #
US 6,100,804 A
Filed 10/29/1998
|
Current Assignee
Intermec IP Corporation
|
Sponsoring Entity
Intermec IP Corporation
|
| Method and apparatus for testing RFID tags | ||
|
Patent #
US 6,104,291 A
Filed 10/06/1998
|
Current Assignee
Intermec IP Corporation
|
Sponsoring Entity
Intermec IP Corporation
|
| System for controlling assets | ||
|
Patent #
US 6,121,878 A
Filed 11/12/1998
|
Current Assignee
Intermec IP Corporation
|
Sponsoring Entity
Intermec IP Corporation
|
| Automated vehicle parking system for a plurality of remote parking facilities | ||
|
Patent #
US 5,737,710 A
Filed 11/07/1995
|
Current Assignee
TC License Limited
|
Sponsoring Entity
Amtech Systems Corporation
|
| Modulated backscatter microstrip patch antenna | ||
|
Patent #
US 5,825,329 A
Filed 07/23/1996
|
Current Assignee
TC License Limited
|
Sponsoring Entity
Amtech Systems Corporation
|
| Electronic system and method for remote identification of coded articles and the like | ||
|
Patent #
US 5,491,482 A
Filed 12/29/1992
|
Current Assignee
Sarnoff Corporation
|
Sponsoring Entity
David Sarnoff Research Center Inc.
|
| System and method for remote identification of coded articles and the like | ||
|
Patent #
US 5,502,445 A
Filed 05/22/1995
|
Current Assignee
Sarnoff Corporation
|
Sponsoring Entity
David Sarnoff Research Center Inc.
|
| Automated vehicle parking system | ||
|
Patent #
US 5,414,624 A
Filed 11/08/1993
|
Current Assignee
Amtech Systems LLC
|
Sponsoring Entity
AVID SYSTEMS CORPORATION
|
| Transponding tag and method | ||
|
Patent #
US 5,430,441 A
Filed 10/12/1993
|
Current Assignee
Motorola Inc.
|
Sponsoring Entity
Motorola Inc.
|
| Emisson validation system | ||
|
Patent #
US 5,343,906 A
Filed 05/15/1992
|
Current Assignee
BIODIGITAL TECHNOLOGIES INC. A CORP. OF TEXAS
|
Sponsoring Entity
BIODIGITAL TECHNOLOGIES INC. A CORP. OF TEXAS
|
| High speed system for reading and writing data from and into remote tags | ||
|
Patent #
US 5,055,659 A
Filed 02/06/1990
|
Current Assignee
TC License Limited
|
Sponsoring Entity
Amtech Systems Corporation
|
| Method and apparatus for cardiac hemodynamic monitor | ||
|
Patent #
US 4,926,868 A
Filed 04/15/1987
|
Current Assignee
Larsen Lawrence E.
|
Sponsoring Entity
Larsen Lawrence E.
|
| Radio-frequency identification system | ||
|
Patent #
US 4,926,187 A
Filed 09/26/1988
|
Current Assignee
Fujitsu Limited
|
Sponsoring Entity
Fujitsu Limited
|
| Stripline doppler radar | ||
|
Patent #
US 4,731,611 A
Filed 06/20/1984
|
Current Assignee
Siemens AG
|
Sponsoring Entity
Siemens AG
|
| Instrusion detection system | ||
|
Patent #
US 4,673,935 A
Filed 01/26/1984
|
Current Assignee
The Boeing Co.
|
Sponsoring Entity
The Boeing Co.
|
| Wireless communication systems and methods | ||
|
Patent #
RE43313E1
Filed 09/20/2007
|
Current Assignee
Round Rock Research LLC
|
Sponsoring Entity
Round Rock Research LLC
|
| System and method for measurement of distance to a tag by a modulated backscatter RFID reader | ||
|
Patent #
US 8,188,908 B2
Filed 07/21/2010
|
Current Assignee
Amtech Systems LLC
|
Sponsoring Entity
Amtech Systems LLC
|
| Methods of processing a wireless communication signal, wireless communication synchronization methods, and a radio frequency identification device communication method | ||
|
Patent #
US 8,218,703 B2
Filed 12/03/2009
|
Current Assignee
Battelle Memorial Institute
|
Sponsoring Entity
Battelle Memorial Institute
|
| System and method for microwave ranging to a target in presence of clutter and multi-path effects | ||
|
Patent #
US 8,742,975 B2
Filed 11/15/2011
|
Current Assignee
Amtech Systems LLC
|
Sponsoring Entity
Amtech Systems LLC
|
| Microwave intrusion or movement detectors | ||
|
Patent #
US 4,195,289 A
Filed 01/31/1978
|
Current Assignee
Vision Systems Ltd.
|
Sponsoring Entity
I.E.I. Proprietary Limited
|
| Microwave components | ||
|
Patent #
US 4,200,870 A
Filed 10/10/1978
|
Current Assignee
Bridgend Processes Limited
|
Sponsoring Entity
Bridgend Processes Limited
|
| MOTION DETECTION SYSTEM WITH SPLIT-RING MONOSTATIC DOPPLER DETECTION | ||
|
Patent #
US 3,703,722 A
Filed 06/02/1971
|
Current Assignee
E-Systems LLC
|
Sponsoring Entity
E-Systems LLC
|
| DIFFERENTIAL DOPPLER DETECTION FOR RF INTRUDER ALARM SYSTEMS | ||
|
Patent #
US 3,728,721 A
Filed 01/28/1971
|
Current Assignee
The Mosler Safe Company Hamilton OH
|
Sponsoring Entity
The Mosler Safe Company Hamilton OH
|
10 Claims
- 1. A homodyne radar transmitter/receiver device comprising:
microwave source means for producing a microwave transmission signal; a combination transmitter/receiver antenna for transmitting said microwave transmission signal and detecting both modulated and unmodulated backscatter signals; transmission line means connecting said microwave source and said combination transmitter/receiver antenna; at least two output connectors attached to said transmission line means at intervals equal to approximately 1/8 wavelength of said microwave transmission signal; means for detecting attached to said output connectors; low pass filter means connected to said means for detecting; signal combiner/amplifier means connected to said low pass filter means for producing a single output containing modulated backscatter information for all phase conditions of said modulated and unmodulated backscatter signals. - View Dependent Claims (2, 4)
- 3. The system of claim wherein said transmission line means comprises a stripline.
- 5. A homodyne radar transmitter/receiver device comprising:
microwave source means for producing a microwave transmission signal; a combination transmitter/receiver antenna for transmitting said microwave transmission signal and detecting both modulated and unmodulated backscatter signals; transmission line means connecting said microwave source and said combination transmitter/receiver antenna; at least three output connectors attached to said transmission line means at intervals equal to approximately 1/6 wavelength of said microwave transmission signal; means for detecting attached to said output connectors; low pass filter means connected to said means for detecting; signal combiner/amplifier means connected to said low pass filter means for producing a single output containing modulated backscatter information for all phae conditions of said modulated and unmodulated backscatter signals.
- 6. In a transponder system, a single antenna homodyne radar system for producing a combined output signal representative of a modulated backscatter signal produced by a transponder regardless of ambiguity points produced by the interference of modulated and unmodulated backscatter signals comprising:
rf source means for generating a microwave transmission signal; antenna means for transmitting said microwave transmission signal and receiving said modulated and unmodulated backscatter signals; transmission line means for connecting said rf source means and said antenna means such that a first standing wave pattern is produced in said transmission line means by the combination of said microwave transmission signal and said modulated backscatter signal and a second standing wave pattern is produced in said transmission line means by the combination of said microwave transmission signal and said unmodulated backscatter signal; a plurality of output channels connected to said transmission line means, said plurality of output channels spaced by a distance equal to approximately 1/8 wavelength of said microwave transmission signal such that at least one channel of each adjacent pair of said plurality of output channels contains said received modulated backscatter signal regardless of ambiguity points caused by the coincidence of said first and second standing wave patterns; means for combining said plurality of output channels to produce a single combined output channel representative of said modulated backscatter signal. - View Dependent Claims (7, 8, 9, 10)
1 Specification
The present invention pertains generally to microwave communication systems and more particularly to radar transponder identification systems. It is a result of a contract with the Department of Energy under contract W-7405-ENG-36.
Homodyne radar systems containing a transponder for purposes such as motor vehicle identification, railroad car identification, inventory control, security systems, locating and tracking vehicles, monitoring from inaccessible locations, downed aircraft location and identification, and biomedical monitoring and identification of animals, etc., depends upon detection of the signal encoded by the transponder. A typical homodyne radar/transponder system is disclosed in FIG. 2 of U.S. Pat. No. 4,075,632 entitled "Interrogation, and Detection System" issued Feb. 21, 1978 to Baldwin et al. In operation, the transmitter/receiver, illustrated in FIG. 2 of the above-referenced patent, samples a portion of the transmitted wave using a directional coupler 40. the sampled transmitted signal is divided into two channels and phase shifted in channel A by 9°. The sampled transmitted signal is then mixed with the received signal which is also divided into two signals by signal splitter 60. After mixing the transmitted and received signals, both channels are amplified. Channel A is then phase shifted by 90° and combined with the signal of channel B to produce a single combined output channel which is filtered to detect the envelope of the coded low frequency modulated signal produced by the transponder.
Since the transponder is located on an object which may be in motion or have a position which is variable, phase differences are introduced between the sampled transmitted signal, i.e., the reference signal, and the received signal. If the reference signal is represented by A cos 2πft, then the received signal can be represented by B cos (2πft+θ), where A is the magnitude of the reference signal, B is the magnitude of the received signal, f is the frequency of the microwave source, t is the time in seconds, and θ is the phase difference between the reference signal and the received signal. The output of mixer B in the above-identified U.S. patent is:
V.sub.out =A cos (2πft)×B cos (2πft+θ). (1)
Using trigonometric identities:
V.sub.out =(AB/2)[cos θ+cos (4πft+θ)]. (2)
If this signal were than filtered by a low frequency filter, such as filter 58 illustrated in FIG. 2 of the above-identified patent, the signal available to be processed digitally is:
V.sub.out =(AB/2) cos ν. (3)
For various phase differences between the reference signal and the receive signal, which are created by changes in the distance between the transponder and the transmitter/receiver, problems of detecting the uncoded transponder signal can develop. For example, if the phase difference θ=nπ/2 where n=1, 3, 5 . . . , then
V.sub.out =0. (4)
In other words, no matter how the transponder has coded the magnitude B of the received signal, no output will be detected at the receiver. These phase differences which cause a zero output are referred to as null positions or ambiguity positions. In space, the ambiguity points occur every one quarter of a wavelength. In practice, these ambiguity points result in a loss of data from the uncoded transponder signals.
These problems are overcome by the device illustrated in FIG. 2 of the above-referenced U.S. Pat. No. 4,075,632, by the introduction of a 90° phase shift of the reference signal in channel A. The two mixers illustrated in FIG. 2 produce the following outputs if each signal were filtered separately.
V.sub.A =(AB/4) cos θ (5)
V.sub.B =(AB/4) sin θ (69
As is apparent, for all values of θ, i.e., all phase differences between the reference signal and the receive signal, at least one of the two channels contains the received signal B. Of course, the same result could be achieved by introducing the 9° phase shift in either channel A or channel B.
Although this eliminates the problem of ambiguity points, the arrangement of power splitters, phase shifters, circulators, directional couplers and other devices, and the use of two antennas, results in a system which is expensive to implement. Commercialization of homodyne radar transponder identification systems would be greatly enhanced by the development of a transmitter/receiver which overcomes these problems at a reduced cost.
It is therefore an object of the present invention to provide an improved single antenna homodyne or radar system.
It is also an object of the present invention to provide an improved homodyne radar transmitter/receiver device.
Another object of the present invention is to provide a homodyne radar transmitter/receiver device for producing a single output containing modulated backscatter information for all phase conditions of both modulated and unmodulated backscatter signals.
Another object of the present invention is to provide a single antenna homodyne radar system for producing a combined output signal representative of a modulated backscatter signal produced by a transponder regardless of the ambiguity points produced by the interference of modulated and unmodulated backscatter signals.
Additional objects, advantages, and novel features of the invention are set forth in part in the description which follows, and will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention as embodied and broadly described herein, the homodyne radar transmitter/receiver device of the present invention may comprise microwave source means for producing a microwave transmission signal; a combination transmitter/receiver antenna for transmitting said microwave transmission signal and detecting both modulated and unmodulated backscatter signals; transmission line means connecting said microwave source and said combination transmitter/receiver antenna; at least two output connectors attached to said transmission line means at intervals equal to approximately 1/8 wavelength of said microwave transmission signal; means for detecting attached to said output connectors; low pass filter means connected to said means for detecting; signal combiner/amplifier means connected to said low pass filter means for producing a signal output containing modulated backscatter information for all phase conditions of said modulated and unmodulated backscatter signals.
The present invention may also comprise, in accordance with its object and purposes, a homodyne radar transmitter/receiver device comprising microwave source means for producing a microwave transmission signal; a combination transmitter/receiver antenna for transmitting said microwave transmission signal and detecting both modulated and unmodulated backscatter signals; transmission line means connecting said microwave source and said combination transmitter/receiver antenna; at least three output connectors attached to said transmission line means at intervals equal to approximately 1/6 wavelength of said microwave transmission signal; means for detecting attached to said output connectors; low pass filter means connected to said means for detecting; signal combiner/amplifier means connected to said low pass filter means for producing a single output containing modulated backscatter information for all phase conditions of said modulated and unmodulated backscatter signals.
The present invention may also comprise, in accordance with its objects and purposes, a single antenna homodyne radar system for producing a combined output signal representative of a modulated backscatter signal produced by a transponder regardless of ambiguity points produced by the interference of modulated and unmodulated backscatter signals comprising rf source means for generating a microwave transmission signal; antenna means for transmitting said microwave transmission signal and receiving said modulated and unmodulated backscatter signals; transmission line means for connecting said rf source means and said antenna means such that a first standing wave pattern is produced in said transmission line means by the combination of said microwave transmission signal and said modulated backscatter signal and a second standing wave pattern is produced in said transmission line means by the combination of said microwave transmission signal and said unmodulated backscatter signal; a plurality of output channels connected to said transmission line means, said plurality of output channels spaced by a distance equal to approximately 1/8 wavelength of said microwave transmission signal such that at least one channel of each adjacent pair of said plurality of output channels contains said received modulated backscatter signal regardless of ambiguity points caused by the coincidence of said first and second standing wave patterns; means for combining said plurality of output channels to produce a single combined output channel representative of said modulated backscatter signal.
The advantages of the present device are that it provides greater sensitivity for receiving transponder signals and can be produced by inexpensive and easily implemented techniques at substantially reduced costs. This greatly enhances the commercialization of homodyne radar identification systems.
FIG. 1 is a schematic block diagram of the preferred embodiment of the invention.
FIG. 2 is a schematic diagram of a device for implementing the preferred embodiment of the invention.
FIG. 3 is a schematic diagram of another device for implementing the preferred embodiment of the invention.
FIG. 4 is a schematic diagram of another device for implementing the preferred embodiment of the invention.
FIG. 5 is a schematic diagram of another manner of implementing the preferred embodiment of the invention.
FIG. 6 is a schematic diagram of another manner of implementing the preferred embodiment of the invention.
FIG. 7 is a graph of a transmitted or forward, traveling wave at three successive points in time.
FIG. 8 is a graph of a 100% reflected traveling wave at three points in time.
FIG. 9 is a graph of a 10% reflected wave at three points in time.
FIG. 10 is a graph of a standing wave produced by a forward traveling wave and a 100% reflected wave at five different points in time.
FIG. 11 is a graph of a forward traveling, a 50% reflected traveling wave and the resultant standing wave.
FIG. 12 is a graph of the standing wave pattern and locus of peaks of the standing wave pattern with a 50% reflection coefficient.
FIG. 13 is a graph of a standing wave pattern and locus of peaks for a 10% reflection coefficient.
FIG. 14 is a graph of locus of peaks for a 10% reflection coefficient.
FIG. 15 is a graph of locus of peaks for a 20% reflection coefficient.
FIG. 16 is a graph of locus of peaks for a 10% reflection coefficient and a 20% reflection coefficient showing ambiguity points each one-quarter wavelength.
FIG. 17 is a graph of the locus of peaks for an 8% reflection coefficient and locus of peaks for a 2% reflection coefficient illustrating the one-quarter wavelength separation of ambiguity points.
FIG. 18 is a graph of the output at an ambiguity point for changes in reflection coefficient of 20% and 40%.
FIG. 19 is a graph of the change in voltage as a function of time for changes in the reflection coefficient from 0.4 to 0.2.
FIG. 1 is a schematic block diagram of the preferred embodiment of the invention. As illustrated in FIG. 1, a microwave source 10 is connected to a transmitter/receiver antenna 12 via a tapped transmission line 14. Although the schematic block diagram of FIG. 1 illustrates two channels, a plurality of channels can be generated by connecting additional outputs to tapped transmission line 14. The spacing between connectors on the tapped transmission line 14 is 1/8 wavelength, 1/6 wavelength, or other spacing, which avoids ambiguity points described infra.
Each of the output connectors attached to the tapped transmission line 14 is connected to a detector such as detectors 16 and 18. The outputs of detectors 16 and 18 are attached to low pass filters 20 and 22. Low pass filters 20 and 22 pass the low frequency modulation information provided by transponder 24. Signal combiner/amplifier 26 combines the outputs of low pass filters 20 and 22 and amplifies the signal to a predetermined level. Digital receiver 28 converts the output of signal combiner/amplifier 26 to a pure digital signal which is displayed in digital display 30.
FIG. 2 illustrates a particular implementation of the device illustrated in FIG. 1. As shown in FIG. 2, a coaxial tranmission line 36 is utilized to attach the microwave source 32 to antenna 34. Taps are provided along the coaxial transmission line 36 which are spaced by 1/8 of a wavelength. Diodes 38 and 40 are utilized as detectors while capacitors 42 and 44 function as low pass filters.
FIG. 3 illustrates another implementation of the device of FIG. 1. As shown in FIG. 3, a microwave source 46 is connected to a transmitter/receiver antenna 48 via a strip transmission line 50 and connecting cables 52 and 54. Taps 56 and 58 are attached along the strip 57 at a spacing which avoids ambiguity points, such as 1/8 wavelength. It should be noted that the wavelength of interest is the wavelength of the transmitted or received signal along the strip transmission line 50. This is additionally true for the coaxial transmission line of FIG. 2 and the waveguide illustrated in FIG. 4. Diodes 60 and 62 are attached to the taps 56 and 58, respectively. Output connecting cables 68 and 70 are attached to output strips 64 and 68. Again, FIG. 3 illustrates one manner of using a strip transmission line which produces two output channels. Also, a plurality of output channels can be produced in the same manner illustrated in FIG. 3.
FIG. 4 illustrates another implementation of the preferred embodiment of the invention illustrated in FIG. 1. As illustrated in FIG. 4, a microwave source 72 produces a microwave signal which is transmitted through connecting cables 74 to a waveguide 76. Output detectors 82 and 84 are connected in the waveguide 76 to produce two output channels which are applied to low pass filters.
FIG. 5 illustrates another method of implementing a plurality of output channels. The circuitry illustrated in FIG. 5 has increased rejection of noise (spurious modulation) of the transmitted rf signal.
FIG. 6 illustrates that other phasing arrangements can also be used. As shown in FIG. 6, spacings of 1/6 wavelength, using three channels, provides an output on at least two channels, at all times.
FIGS. 1-6 illustrate the preferred embodiment of the invention and various manners of implementation of the preferred embodiment of the invention. FIGS. 7-19 illustrate the operation of the invention and an inventive aspect of the invention, i.e., the ability to provide an output signal on at least one of a plurality of channels at all times.
FIG. 7 illustrates the transmitted wave produced by the microwave source 10 at three successive points in time. As shown in FIG. 7, the transmitted or forward wave is a traveling wave which is applied to the tapped transmission line 14 and transmitted by transmitter/receiver antenna 12 illustrated in FIG. 1. Since the forward wave illustrated in FIG. 7 is a traveling wave, it would appear on the tapped transmission line 14 (FIG. 1) as it is shown in FIG. 7 at three successive instances of time.
FIG. 8 is an illustration of a 100% reflected traveling wave. The traveling wave illustrated in FIG. 8 can be reflected by mismatching of the impedance of the transmitter/receiver antenna 12 or radar reflection of the transmitted wave illustrated in FIG. 7 by objects in line with the transmitter/receiver antenna 12. Normally, the reflected wave in a homodyne radar system such as illustrated in FIG. 1 never approaches 100% reflection. Again, the reflected wave would appear on the tapped transmission line 14 in the manner shown in FIG. 8 at three successive instances of time.
FIG. 9 is a graph of a 10% reflected wave which more accurately illustrates the type of reflected wave produced in the tapped transmission line 14.
FIG. 10 is a schematic illustration of the standing waveform pattern produced in the tapped transmission line 14 by the interference of the transmitted or forward wave illustrated in FIG. 7 and a 100% reflected traveling wave illustrated in FIG. 8. As shown in FIG. 10 the standing waveform pattern does not travel along the tapped transmission line 14 but remains stationary and oscillates from positive to negative.
FIG. 11 illustrates a forward wave 86, a 50% reflected wave 88, and the resultant or standing wave 90. As is apparent from FIG. 11, the resultant waveform 90 is unlike the standing waveform illustrated in FIG. 10 in that it is a traveling wave in addition to having a variable magnitude.
This is more clearly illustrated in FIG. 12 which shows the resultant waveform 90 at three successive points in time and the locus of peaks 92 produced by the resultant waveform 90. It should be noted that the locus of peaks 92 has a wavelength which is one half of the wavelength of the resultant waveform 90.
FIG. 13 illustrates the resultant waveform 94 produced by the interference of the transmitted wave 89 illustrated in FIG. 7 and a 10% reflected wave 91 illustrated in FIG. 9. The locus of peaks 96 produced by the resultant waveform 94 also has a wavelength equal to one half of the wavelength of the resultant wave and the transmitted and reflected waves.
FIG. 14 illustrates the locus of peaks 98 which corresponds to locus of peaks 96 illustrated in FIG. 13 which is generated by the interference of the transmitted wave and a 10% reflected wave.
FIG. 15 illustrates the locus of peaks 100 produced by a resultant wave which was generated by the interference of the transmitted wave and a 20% reflected wave.
FIG. 16 illustrates the locus of peaks waveform 98 for a 10% reflected wave, as shown in FIG. 14, and the locus of peaks waveform 100 produced by a 20% reflected wave as illustrated in FIG. 15, and the resultant intersection points 99 of these two waveforms. As shown in FIG. 16, the locus of peaks waveforms 98 and 100 intersect at distances equal to substantially 1/4 wavelength of the transmitted wave. The intersection points 99 are referred to as ambiguity points or null points. FIG. 17 more clearly illustrates that these ambiguity points or null points occur at intervals which very closely approximate 1/4 wavelength in actual implementation of the device of FIG. 1.
FIG. 17 illustrates a locus of peaks 102 for a reflection coefficient of 2% and locus of peaks 104 for a reflection coefficient of 8% between 0.9 volts and 1.1 volts for a 1 volt forward wave. The ambiguity points 106, as clearly shown in FIG. 17, occur at spacings substantially equal to 1/4 wavelength of the transmitted wave.
The location of the ambiguity points or null points is extremely important to the operation of the homodyne radar system illustrated in FIG. 1. In operation, the microwave source 10 of FIG. 1 produces a forward traveling wave such as wave 89 illustrated in FIG. 7. Forward wave 89 is applied to tapped transmission line 14 and transmitted by transmitter/receiver antenna 12 to transponder 24. Transponder 24 amplitude modulates the transmitted signal 89 according to a particular code which identifies the particular transponder 24, as disclosed in the above referenced U.S. Pat. No. 4,075,632. In addition to the transponder signal received by transmitter/receiver antenna 12, reflected signals such as the 10% reflected wave 91 illustrated in FIG. 9 are received by the transmitter/receiver antenna 12. The transmitted forward traveling wave signal and the various reflected signals produce resultant waveforms in the tapped transmission line 14.
FIGS. 14 and 15 illustrate the locus of points of the resultant waves for a 10% reflected wave and a 20% reflected wave, respectively. The two waveforms 98 and 100 are shown superimposed upon one another in FIG. 16 as they would appear in tappd transmission line 14 of FIG. 1. As illustrated in FIG. 16, if a detector were placed at the ambiguity points 99 on the tapped transmission line 14, it would be impossible to distinguish between waveforms 98 and 100. Consequently, a detector placed at an ambiguity point along the tapped transmission line 14 would be unable to detect a change in modulation of one of the waveforms 98. This is a result of the fact that the location of the ambiguity points is determined by the phase of the reflected signals and, consequently, the distance of the transponder 24 from the homodyne radar transmitter/receiver device illustrated in FIG. 1, rather than by the magnitude of the reflected signals.
FIG. 17 clearly illustrates that the ambiguity points 106 are separated by substantially 1/4 wavelength. Consequently, if at least two channels are placed at a separation equal to approximately 1/8 wavelength, at least one of the two channels will always contain information of the amplitude modulated signal produced by transponder 24. By combining the output of the plurality of channels, a single combined output channel is produced which contains the modulated backscatter signal information from transponder 24.
The operation of the device of the present invention can be described mathematically. The transmitted wave is represented by: ##EQU1## while the received wave is represented by: ##EQU2## where λ is the wavelength along the transmission line, and x is the distance along the line. The value of x increases going to the right as illustrated in FIG. 1. The total wave on the tapped transmission line 14 is the sum of the transmitted and received waves.
V=V.sub.T +V.sub.R (9)
The total wave (V) is the resultant wave illustrated in FIG. 10, FIG. 11 (waveform 90), FIG. 12 (waveform 90), and FIG. 13 (waveform 94). To detect the resultant wave described above, a tap is placed along the transmission line 14 at a location x. The voltage at the tap is: ##EQU3## the rectified or detected output voltage, Vo, is the magnitude of V. In other words:
V.sub.o =|V| (11)
letting ρ=B/A: ##EQU4## Equation 12 is representative of the locus of peaks illustrated in FIG. 12 (waveform 92), FIG. 13 (waveform 96), FIGS. 14, 15, and 16 (waveforms 98 and 100), and FIG. 17 (waveforms 102 and 104).
If a channel is placed at: ##EQU5## then:
V.sub.o =A (14)
which is independent of ρ and the magnitude of the scattered signal. In other words, at the locations indicated by Equation 13, the rectified output signal is independent of the modulation coefficient B produced by the transponder 24. These positions are called ambiguity points.
As is apparent from Equation 13, the ambiguity points occur at approximately 1/4 wavelength of the placement of the tap along transmission line 14. Information encoded by transponder 14 is unattainable at these ambiguity points.
The present invention overcomes the problems which occur as a result of these ambiguity points by providing a plurality of taps which are spaced by 1/8 wavelength. In practice, ρ is very small. Using this approximation, the ambiguity points occur at: ##EQU6## If a second tap is placed 1/8 wavelength from these ambiguity points, the signal at the second tap is:
V.sub.o =A(1+ρ), (17)
which is the maximum received signal.
In reality, a large unmodulated received signal is present in addition to the desired modulated signal from the transponder. However, since the homodyne receiver detects changes in the received signal, i.e. changes in ρ, the same analysis is directly applicable to the homodyne radar system illustrated in FIG. 1.
Consequently, the present invention provides a homodyne radar transmitter/receiver device which is capable of producing a single output which contains modulated backscatter information for all phase conditions of both modulated and unmodulated backscatter signals. This is achieved using inexpensive techniques which greatly reduce the capital investment in the homodyne radar transmitter/receiver device and which can be implemented in a simple and easy manner.
The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.