Time-based correction technique for multistatic radar system
A system includes first and second radar transceivers, a processor, and a non-transitory computer-readable medium storing machine instructions. The machine instructions cause the processor to determine a first frequency offset a 1 and a first initial time offset τ initial;1 between a first clock signal for the first radar transceiver and a reference clock for the processor, and the processor determines a first clock drift for the first clock signal relative to the reference clock based on the frequency offset a 1 and the time offset τ initial;1 . The processor determines a second frequency offset a 2 and a second initial time offset τ initial;2 between a second clock signal for the second radar transceiver and the reference clock, and a second clock drift for the second clock signal relative to the reference clock based on the frequency offset a 2 and the time offset τ initial;2 . The processor then compensates for the first and second clock drift.
1 . A system comprising:
a first radar transceiver and a second radar transceiver;
at least one processor; and
at least one non-transitory computer-readable medium storing machine instructions which, when executed by the at least one processor, cause the at least one processor to:
determine a first clock offset α 1 and a first initial time offset τ initial;1 between a first clock signal for the first radar transceiver and a reference clock for the at least one processor;
determine a first clock drift for the first clock signal relative to the reference clock based on the first clock offset α 1 and the first initial time offset τ initial;1 ;
determine a second clock offset α 2 and a second initial time offset τ initial;2 between a second clock signal for the second radar transceiver and the reference clock;
determine a second clock drift for the second clock signal relative to the reference clock based on the second clock offset α 2 and the second initial time offset τ initial;2 ; and
compensate for the first and second clock drift by applying the first clock drift to transmitted or received radar signals of the first radar transceiver and the second clock drift to transmitted or received radar signals of the second radar transceiver.
2 . The system of claim 1 , wherein the machine instructions to determine the first clock offset α 1 comprise machine instructions to determine the first clock offset α 1 based on signal timestamp information between the first radar transceiver and the at least one processor, and wherein the machine instructions to determine the second clock offset α 2 comprise machine instructions to determine the second clock offset α 2 based on signal timestamp information between the second radar transceiver and the at least one processor.
3 . The system of claim 1 , wherein the machine instructions to compensate for the first and second clock drift comprise machine instructions to:
manipulate a first oscillation frequency of the first clock signal based on the first clock offset α 1 ; and
manipulate a second oscillation frequency of the second clock signal based on the second clock offset α 2 .
4 . The system of claim 1 , wherein the machine instructions to compensate for the first and second clock drift comprise machine instructions to:
determine a relative clock drift between the first and second clock signals based on a relative clock offset (α 1 −α 2 ) corresponding to a difference between the first and second clock offsets α 1 and α 2 ; and
apply a frequency compensation to received radar signals from the first and second radar transceivers, wherein the frequency compensation is based on the relative clock offset α 1 −α 2 .
5 . The system of claim 4 , wherein an instantaneous time offset between the first and second radar transceiver clock signals is represented as:
τ
offset
=
τ
initial
+
t
(
(
α
1
-
α
2
)
)
where τ offset is the instantaneous time offset between the first and second radar transceiver clock signals, τ initial is an initial time offset between the first and second clock signals, t is a current time, and t((α 1 −α 2 )) represents a product of the current time and the relative clock offset.
6 . The system of claim 5 , wherein the frequency compensation for the received radar signals is represented as:
f
correction
(
q
)
=
[
τ
initial
+
q
*
T
chirp
*
(
a
1
-
a
2
)
]
*
Δ
F
T
acq
where f correction (q) is the frequency compensation for a chirp index q, Tchirp is a period of a chirp signal, ΔF represents a bandwidth of the chirp signal, and Tacq is a period of a data acquisition time.
7 . The system of claim 1 , wherein the machine instructions to compensate for the first and second clock drift comprise machine instructions to:
apply a first frequency compensation to radar signals to be transmitted by the first radar transceiver based on the first clock offset α 1 ; and
apply a second frequency compensation to radar signals to be transmitted by the second radar transceiver based on the second clock offset α 2 .
8 . A non-transitory computer-readable medium storing machine instructions which, when executed by at least one processor, cause the at least one processor to:
determine a first clock offset α 1 and a first initial time offset τ initial;1 between a first clock signal for a first radar transceiver and a reference clock for the at least one processor;
determine a first clock drift for the first clock signal relative to the reference clock based on the first clock offset α 1 and the first initial time offset τ initial;1 ;
determine a second clock offset α 2 and a second initial time offset τ initial;2 between a second clock signal for a second radar transceiver and the reference clock;
determine a second clock drift for the second clock signal relative to the reference clock based on the second clock offset α 2 and the second initial time offset τ initial;2 ; and
compensate for the first and second clock drift by applying the first clock drift to transmitted or received radar signals of the first radar transceiver and the second clock drift to transmitted or received radar signals of the second radar transceiver.
9 . The non-transitory computer-readable medium of claim 8 , wherein the machine instructions to determine the first clock offset α 1 comprise machine instructions to determine the first clock offset α 1 based on signal timestamp information between the first radar transceiver and the at least one processor, and wherein the machine instructions to determine the second clock offset α 2 comprise machine instructions to determine the second clock offset α 2 based on signal timestamp information between the second radar transceiver and the at least one processor.
10 . The non-transitory computer-readable medium of claim 8 , wherein the machine instructions to compensate for the first and second clock drift comprise machine instructions to:
manipulate a first oscillation frequency of the first clock signal based on the first clock offset α 1 ; and
manipulate a second oscillation frequency of the second clock signal based on the second clock offset α 1 .
11 . The non-transitory computer-readable medium of claim 8 , wherein the machine instructions to compensate for the first and second clock drift comprise machine instructions to:
determine a relative clock drift between the first and second clock signals based on a relative clock offset (α 1 −α 2 ) corresponding to a difference between the first and second clock offsets α 1 and α 2 ; and
apply a frequency compensation to received radar signals from the first and second radar transceivers, wherein the frequency compensation is based on the relative clock offset α 1 −α 2 .
12 . The non-transitory computer-readable medium of claim 11 , wherein an instantaneous time offset between the first and second radar transceiver clock signals is represented as:
τ
offset
=
τ
initial
+
t
(
(
α
1
-
α
2
)
)
where τ offset is the instantaneous time offset between the first and second radar transceiver clock signals, τ initial is an initial time offset between the first and second clock signals, t is a current time, and t((α 1 −α 2 )) represents a product of the current time and the relative clock offset.
13 . The non-transitory computer-readable medium of claim 12 , wherein the frequency compensation for the received radar signals is represented as:
f
correction
(
q
)
=
[
τ
initial
+
q
*
T
chirp
*
(
a
1
-
a
2
)
]
*
Δ
F
T
acq
where f correction (q) is the frequency compensation for a chirp index q, Tchirp is a period of a chirp signal, ΔF represents a bandwidth of the chirp signal, and Tacq is a period of a data acquisition time.
14 . The non-transitory computer-readable medium of claim 8 , wherein the machine instructions to compensate for the first and second clock drift comprise machine instructions to:
apply a first frequency compensation to radar signals to be transmitted by the first radar transceiver based on the first clock offset α 1 ; and
apply a second frequency compensation to radar signals to be transmitted by the second radar transceiver based on the second clock offset α 2 .
15 . A method comprising:
determining a first clock offset α 1 and a first initial time offset τ initial;1 between a first clock signal for a first radar transceiver and a reference clock for at least one processor;
determining a first clock drift for the first clock signal relative to the reference clock based on the first clock offset α 1 and the first initial time offset τ initial;1 ;
determining a second clock offset α 1 and a second initial time offset τ initial;2 between a second clock signal for a second radar transceiver and the reference clock;
determining a second clock drift for the second clock signal relative to the reference clock based on the second clock offset α 1 and the second initial time offset τ initial;2 ; and
compensating for the first and second clock drift by applying the first clock drift to transmitted or received radar signals of the first radar transceiver and the second clock drift to transmitted or received radar signals of the second radar transceiver.
16 . The method of claim 15 , wherein determining the first frequency offset a 1 comprises determining the first clock offset α 1 based on signal timestamp information between the first radar transceiver and the at least one processor, and wherein determining the second clock offset α 2 comprises determining the second clock offset α 2 based on signal timestamp information between the second radar transceiver and the at least one processor.
17 . The method of claim 15 , wherein compensating for the first and second clock drift comprises:
manipulating a first oscillation frequency of the first clock signal based on the first clock offset α 1 ; and
manipulating a second oscillation frequency of the second clock signal based on the second clock offset α 2 .
18 . The method of claim 15 , wherein compensating for the first and second clock drift comprises:
determining a relative clock drift between the first and second clock signals based on a relative clock offset (α 1 −α 2 ) corresponding to a difference between the first and second offsets α 1 and α 2 ; and
applying a frequency compensation to received radar signals from the first and second radar transceivers, wherein the frequency compensation is based on the relative clock offset α 1 −α 2 .
19 . The method of claim 18 , wherein an instantaneous time offset between the first and second radar transceiver clock signals is represented as:
τ
offset
=
τ
initial
+
t
(
(
α
1
-
α
2
)
)
where τ offset is the instantaneous time offset between the first and second radar transceiver clock signals, τ initial is an initial time offset between the first and second clock signals, t is a current time, and t((α 1 −α 2 )) represents a product of the current time and the relative clock offset.
20 . The method of claim 19 , wherein the frequency compensation for the received radar signals is represented as:
f
correction
(
q
)
=
[
τ
initial
+
q
*
T
chirp
*
(
a
1
-
a
2
)
]
*
Δ
F
T
acq
where f correction (q) is the frequency compensation for a chirp index q, Tchirp is a period of a chirp signal, ΔF represents a bandwidth of the chirp signal, and Tacq is a period of a data acquisition time.
21 . The method of claim 15 , wherein compensating for the first and second clock drift comprises:
applying a first frequency compensation to radar signals to be transmitted by the first radar transceiver based on the first clock offset α 1 ; and
applying a second frequency compensation to radar signals to be transmitted by the second radar transceiver based on the second clock offset α 1 .