Data processing: measuring – calibrating – or testing – Measurement system – Speed
Reexamination Certificate
1999-06-11
2002-08-13
Hoff, Marc S. (Department: 2852)
Data processing: measuring, calibrating, or testing
Measurement system
Speed
C342S112000
Reexamination Certificate
active
06434506
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for determining the relative velocity in the radial direction between two moving objects, using linear frequency modulation with continuous frequency sweeps, a transmitted signal being multiplied by a received signal for the attainment of a resultant received signal, the phase change of which over a certain time is used to determine the relative velocity.
2. Description of Related Art
A problem in determining the velocity where linear frequency modulation is used is to be able clearly to determine the phase difference. The phase change is normally only known at ±n·2&pgr;, where n is a positive integer.
SUMMARY OF THE INVENTION
The object of the present invention is to realize a process in which the phase difference can clearly be determined. The object of the invention is achieved by a process characterized in that the period length for successive frequency sweeps is varied and in that the difference in period length and corresponding phase change is used to determine the velocity. By studying the phase change over a time period which can be made significantly shorter than the period length for a frequency sweep, the phase change can be kept within a clear interval.
The relative velocity v is advantageously calculated from the relationship:
v=k·x/&Dgr;T,
where x is the phase difference during the time &Dgr;T and
k
=
c
/
2
π
2
α
t
c
+
2
f
0
,
where
c denotes the velocity of the light in air, &agr; denotes the gradient of the frequency sweep, t
c
denotes the clock time and f
0
denotes the carrier frequency of the signal.
The period length from a first to a second frequency sweep is changed by an amount less than or equal to the time difference which is required to be able clearly to determine the phase change on the basis of given limit values for distance apart, velocity and acceleration.
At least three successive frequency sweeps are expediently assigned a different period length.
In order to increase the accuracy in the velocity determination, the time interval during which the phase change is studied is progressively increased without any loss of clarity. An advantageous process is characterized in that phase changes, over and above for differences in period lengths, are studied for one or more period lengths and/or one or more added period lengths.
REFERENCES:
patent: 3737233 (1973-06-01), Blau et al.
patent: 3750170 (1973-07-01), Brown
patent: 3750172 (1973-07-01), Tersselt
patent: 4103302 (1978-07-01), Roeder et al.
patent: 4106017 (1978-08-01), Roeder et al.
patent: 4620192 (1986-10-01), Collins
patent: 4851851 (1989-07-01), Hame
patent: 5334985 (1994-08-01), Tucker et al.
patent: 5483242 (1996-01-01), Grein et al.
patent: 5563602 (1996-10-01), Stove
Eckersten Christer
Eriksson Gudrun Wallin
Eriksson Lars H.
Felter Stefan
Celsiustech Electronics AB
Charioui Mohamed
Connolly Bove & Lodge & Hutz LLP
Eriksson Gudrun Wallin
Hoff Marc S.
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