Communications: directive radio wave systems and devices (e.g. – Testing or calibrating of radar system – By monitoring
Reexamination Certificate
1999-06-25
2002-06-25
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Testing or calibrating of radar system
By monitoring
C342S070000, C342S165000, C342S173000, C342S195000
Reexamination Certificate
active
06411252
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a device for testing the performance accuracy of components in an automotive collision avoidance radar system.
2. Description of the Related Art
A collision avoidance radar operates by transmitting a signal from an antenna typically located in the grill area of an automobile. The collision avoidance radar then determines from a return signal received a distance an object is located from an automobile and a rate the object causing the return signal is moving relative to the automobile.
Collision avoidance radars in the United States are configured to operate within a narrow band millimeter frequency range of 76-77 GHz allocated by the Federal Communications Commission (FCC). To assure proper performance of a collision avoidance radar system, testing is periodically performed to assure components of the system are operating within the 76-77 GHz range specified by the FCC. Testing is further periodically performed to assure that the system is radiating adequate power and to pinpoint components which are not functioning properly if the system is not providing adequate power, or operating outside desired frequency ranges. Such testing is typically performed using a vector network analyzer (VNA).
Components typically used in a VNA setup to make measurements in the 76-77 GHz range are shown in FIG.
1
. The typical VNA illustrated includes an external millimeter wave reflectometer
110
whose stimulus is provided from a signal synthesizer
100
located external to the reflectometer
110
. The local oscillator (LO) input to the reflectometer
110
is provided from a tunable synthesizer
112
, also located separate from the reflectometer
110
. VNAs that include components to make measurements in the millimeter range, as shown in
FIG. 1
, include the ANRITSU™ 37000 and ANRITSU™ 360 series VNAs manufactured by Anritsu Company of Morgan Hill Calif. Other VNAs having components shown in
FIG. 1
include the HP 8510m series VNAs manufactured by Hewlett Packard.
The reflectometer
110
includes millimeter wave multipliers
102
and
104
providing the signal from the synthesizer
100
to a device under test (DUT)
104
. The multipliers
102
and
104
multiply the frequency of a signal from the synthesizer by a factor of four or more to achieve a 76-77 GHz output. The DUT
104
is connected to the reflectometer
110
using WR-12 wave guide forming test ports
106
and
107
to provide the 76-77 GHz output. The synthesizer
100
is connected to the reflectometer
110
using coaxial connectors. Amplifiers, isolators, attenuators, and couplers are further provided in the path between the coaxial connector inputs and WR-12 waveguide test ports
106
and
107
, as shown in FIG.
1
.
Intermediate Frequency (IF) output signals are provided from the reflectometer
110
using superheterodyne harmonic millimeter wave mixers
121
-
124
. The LO signal from synthesizer
112
is provided to one input of each of the mixers
121
-
124
through amplifiers, isolators, and power dividers as shown in FIG.
1
. The IF signals from the mixers
121
-
124
are provided back to a VNA for further down-conversion and processing.
The couplers
131
-
134
provide a second input to each one of the mixers
121
-
124
. Couplers
131
and
133
couple an incident signal traveling from multipliers
102
and
104
to mixers
121
and
123
. Couplers
132
and
134
couple signals reflected from the DUT
104
or transmitted through the DUT
104
to the mixers
122
and
124
.
The performance of the system shown in
FIG. 1
is limited in several ways. First, the frequency switching time for the synthesizer
100
is typically slow (~5 to 15 milliseconds). The slow switching speed is due to high resolution available over a broad bandwidth of signals typically provided from the instrument grade synthesizer
100
. Second, the nonlinearity of multipliers
102
and
104
prevent the signal provided to the test ports
106
and
107
from having a flat output power as a function of frequency. Third, a harmonic higher than the first order is typically required from harmonic mixers
121
-
124
so that a lower frequency LO signal from the LO synthesizer
112
can achieve a desired IF output frequency. Using a higher order harmonic from the mixers
121
-
124
results in a significant conversion loss. Fourth, the cost of instrument grade synthesizers typically used for the stimulus synthesizer
100
and local oscillator synthesizer
112
in a VNA can be excessive.
SUMMARY OF THE INVENTION
The present invention provides a test system used with a stimulus synthesizer operating over a narrow frequency range. With a narrow bandwidth stimulus synthesizer, frequency switching time can be increased. Further, the cost of the stimulus synthesizer can be reduced relative to a broadband instrument grade synthesizer. Further, a synthesizer referenced to the stimulus synthesizer can be used to provide the LO with a significant cost reduction over an instrument grade LO synthesizer.
The present invention further provides a test signal from the stimulus synthesizer to a DUT without an intervening multiplier, enabling a flat power output as a function of frequency.
The present invention further uses a fundamental or a first harmonic for all up-conversions and down-conversions so conversion losses can be avoided.
The present invention is a test system including a narrowband SCORPION™ VNA manufactured by Anritsu Company, a dielectric resonator oscillator (DRO) for providing a LO signal, and a test module.
The Scorpion VNA includes a stimulus synthesizer producing a test signal ranging from 3 GHz to 6 GHz to selectively provide at two input ports of the test module. The Scorpion VNA further receives 3 to 6 GHz IF output signals from the test module and down-converts these signals to provide to a DSP.
The test module includes linear up-converters to translate the 3 to 6 GHz output signal from the Scorpion VNA to provide signals in a 75-78 GHz range to test ports of the test module. The test module avoids multipliers between the VNA and test ports of the test module to create a flat output power vs. frequency signal.
The DRO for providing the LO signal produces a 18 GHz output phase locked to the Scorpion VNA crystal oscillator. The 18 GHz is multiplied times four to 72 GHz. The 72 GHz Lo is used to up-convert the 3 to 6 GHz output of the Scorpion system to a 75 to 78 GHz frequency band. Down-converters further use the 72 GHz LO to translate the 75 to 78 GHz signal from the test module to IF signals in the 3 to 6 GHz range to be detected and measured by the Scorpion VNA.
REFERENCES:
patent: 3723870 (1973-03-01), Donahue
patent: 3745579 (1973-07-01), Lott
patent: 3831088 (1974-08-01), Ort et al.
patent: 3832712 (1974-08-01), Goetz et al.
patent: 3860925 (1975-01-01), Darboven, Jr.
patent: 3924341 (1975-12-01), Edelsohn
patent: 4209786 (1980-06-01), Barley et al.
patent: 4435712 (1984-03-01), Kipp
patent: 4477811 (1984-10-01), Collins, IV
patent: 4660041 (1987-04-01), Maples et al.
patent: 4679049 (1987-07-01), Riffiod
patent: 4686534 (1987-08-01), Eddy
patent: 4970519 (1990-11-01), Minnis et al.
patent: 4972192 (1990-11-01), Bruder
patent: 5111208 (1992-05-01), Lopez
patent: 5138325 (1992-08-01), Koury
patent: 5164734 (1992-11-01), Fredericks et al.
patent: 5181036 (1993-01-01), Miler et al.
patent: 5223840 (1993-06-01), Cronyn
patent: 5351054 (1994-09-01), Fredericks et al.
patent: 5384572 (1995-01-01), Michaels et al.
patent: 5546090 (1996-08-01), Roy, III et al.
patent: 5677696 (1997-10-01), Silverstein et al.
patent: 5920281 (1999-07-01), Grace
Anritsu Company
Fliesler Dubb Meyer & Lovejoy LLP
Gregory Bernarr E.
LandOfFree
Narrow band millimeter wave VNA for testing automotive... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Narrow band millimeter wave VNA for testing automotive..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Narrow band millimeter wave VNA for testing automotive... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2939374