Signal generating method and radar system
A signal generating method for a radar system includes generating a first chirp signal and a second chirp signal having a first time delay relative to the first chirp signal; and combining the first chirp signal and the second chirp signal to determine a frequency modulated signal, wherein the first chirp signal and the second chirp signal are N-step linear stepped frequency modulated continuous waves having the same frequency modulation bandwidth, such that the frequency modulated signal includes i steps of the first chirp signal in a first duration, an interleaved combination of N−i steps of the first chirp signal and N−i steps of the second chirp signal in a second duration, and i steps of the second chirp signal in a third duration.
1. A signal generating method for a radar system, the radar system comprising a transmitting device, the signal generating method comprising:
the transmitting device generating a first chirp signal and a second chirp signal having a first time delay relative to the first chirp signal;
the transmitting device combining the first chirp signal and the second chirp signal to determine a frequency modulated signal, wherein the first chirp signal and the second chirp signal are N-step linear stepped frequency modulated continuous waves having a same first frequency modulation bandwidth, such that the frequency modulated signal comprises i steps of the first chirp signal in a first duration, an interleaved combination of N−i steps of the first chirp signal and N−i steps of the second chirp signal in a second duration, and i steps of the second chirp signal in a third duration, where i is smaller than N; and
the transmitting device emitting the frequency modulated signal;
wherein i>1 and i=T delay1 /T s , where T delay1 represents the first time delay between the first chirp signal and second chirp signal, and T s represents time interval of each step of the first chirp signal and second chirp signal.
2. The signal generating method of claim 1 , wherein the frequency modulated signal is determined according to the following function:
f
p
[
k
]
=
{
f
1
[
k
]
,
∀
k
=
0
~
i
-
1
f
1
[
k
+
i
2
]
,
mod
(
k
,
2
)
=
mod
(
i
,
2
)
and
∀
k
=
i
~
2
×
N
-
i
-
1
f
2
[
(
k
-
1
-
i
)
2
]
,
mod
(
k
,
2
)
≠
mod
(
i
,
2
)
and
∀
k
=
i
~
2
×
N
-
i
-
1
f
2
[
k
-
N
]
,
∀
k
=
2
×
N
-
i
~
2
×
N
-
1
where f p represents the frequency modulated signal, f 1 represents the first chirp signal, f 2 represents the second chirp signal, and k represents step number.
3. The signal generating method of claim 1 , wherein the frequency modulated signal further comprises a third chirp signal and a fourth chirp signal, the third chirp signal and the fourth signal are M-step linear stepped frequency modulated continuous waves having a same second frequency modulation bandwidth, and the fourth chirp signal has a second time delay relative to the third chirp signal, such that the frequency modulated signal comprises j steps of the third chirp signal in a fourth duration, an interleaved combination of M−j steps of the third chirp signal and M−j steps of the fourth chirp signal in a fifth duration, and j steps of the fourth chirp signal in a sixth duration, where j is smaller than M.
4. The signal generating method of claim 3 , wherein M is equal to N.
5. The signal generating method of claim 4 , wherein the frequency modulated signal is determined according to the following function:
f
p
[
k
]
=
{
f
1
[
k
]
,
∀
k
=
0
~
i
-
1
f
1
[
k
+
i
2
]
,
mod
(
k
,
2
)
=
mod
(
i
,
2
)
and
∀
k
=
i
~
2
×
N
-
i
-
1
f
2
[
(
k
-
1
-
i
)
2
]
,
mod
(
k
,
2
)
≠
mod
(
i
,
2
)
and
∀
k
=
i
~
2
×
N
-
i
-
1
f
2
[
k
-
N
]
,
∀
k
=
2
×
N
-
i
~
2
×
N
-
1
f
3
[
k
-
2
N
]
,
∀
k
=
2
N
~
2
N
+
j
-
1
f
3
[
(
k
-
2
N
+
j
)
2
]
,
mod
(
k
,
2
)
=
mod
(
j
,
2
)
and
∀
k
=
2
N
+
j
~
4
×
N
-
j
-
1
f
4
[
(
k
-
2
N
-
j
-
1
)
2
]
,
mod
(
k
,
2
)
≠
mod
(
j
,
2
)
and
∀
k
=
2
N
+
j
~
4
×
N
-
j
-
1
f
4
[
k
-
3
N
]
,
∀
k
=
4
×
N
-
j
~
4
×
N
-
1
where f p represents the frequency modulated signal, f 1 represents the first chirp signal, f 2 represents the second chirp signal, f 3 represents the third chirp signal, f 4 represents the fourth chirp signal, k represents step number.
6. The signal generating method of claim 3 , wherein the first chirp signal and the second chirp signal are up chirp signals and the third chirp signal and the fourth chirp signal are down chirp signals.
7. The signal generating method of claim 3 , wherein a frequency shift exists between the maximum frequency of the first and the second chirp signals and the maximum frequency of the third and the fourth chirp signals.
8. A radar system, comprising:
a transmitting device, comprising:
a chirp signal generator, for generating a first chirp signal and a second chirp signal having a first time delay relative to the first chirp signal;
a signal processing module, for combining the first chirp signal and the second chirp signal to determine a frequency modulated signal, wherein the first chirp signal and the second chirp signal are N-step linear stepped frequency modulated continuous waves having a same first frequency modulation bandwidth, such that the frequency modulated signal comprises i steps of the first chirp signal in a first duration, an interleaved combination of N−i steps of the first chirp signal and N−i steps of the second chirp signal in a second duration, and i steps of the second chirp signal in a third duration, where i is smaller than N; and
a transmitting antenna, for emitting the frequency modulated signal; and
at least one receiving device, for receiving reflected signals of the frequency modulated signal;
wherein i>1 and i=T delay1 /T s , where T delay1 represents the first time delay between the first and second chirp signals, and T s represents a time interval of each step of the first chirp signal and second chirp signal.
9. The radar system of claim 8 , wherein the frequency modulated signal is determined according to the following function:
f
p
[
k
]
=
{
f
1
[
k
]
,
∀
k
=
0
~
i
-
1
f
1
[
k
+
i
2
]
,
mod
(
k
,
2
)
=
mod
(
i
,
2
)
and
∀
k
=
i
~
2
×
N
-
i
-
1
f
2
[
(
k
-
1
-
i
)
2
]
,
mod
(
k
,
2
)
≠
mod
(
i
,
2
)
and
∀
k
=
i
~
2
×
N
-
i
-
1
f
2
[
k
-
N
]
,
∀
k
=
2
×
N
-
i
~
2
×
N
-
1
where f p represents the frequency modulated signal, f 1 represents the first chirp signal, f 2 represents the second chirp signal, and k represents step number.
10. The radar system of claim 8 , wherein the frequency modulated signal further comprises a third chirp signal and a fourth chirp signal, the third chirp signal and the fourth signal are M-step linear stepped frequency modulated continuous waves having a same second frequency modulation bandwidth, and the fourth chirp signal has a second time delay relative to the third chirp signal, such that the frequency modulated signal comprises j steps of the third chirp signal in a fourth duration, an interleaved combination of M−j steps of the third chirp signal and M−j steps of the fourth chirp signal in a fifth duration, and j steps of the fourth chirp signal in a sixth duration, where j is smaller than M.
11. The radar system of claim 10 , wherein M is equal to N.
12. The radar system of claim 11 , wherein the frequency modulated signal is determined according to the following function:
f
p
[
k
]
=
{
f
1
[
k
]
,
∀
k
=
0
~
i
-
1
f
1
[
k
+
i
2
]
,
mod
(
k
,
2
)
=
mod
(
i
,
2
)
and
∀
k
=
i
~
2
×
N
-
i
-
1
f
2
[
(
k
-
1
-
i
)
2
]
,
mod
(
k
,
2
)
≠
mod
(
i
,
2
)
and
∀
k
=
i
~
2
×
N
-
i
-
1
f
2
[
k
-
N
]
,
∀
k
=
2
×
N
-
i
~
2
×
N
-
1
f
3
[
k
-
2
N
]
,
∀
k
=
2
N
~
2
N
+
j
-
1
f
3
[
(
k
-
2
N
+
j
)
2
]
,
mod
(
k
,
2
)
=
mod
(
j
,
2
)
and
∀
k
=
2
N
+
j
~
4
×
N
-
j
-
1
f
4
[
(
k
-
2
N
-
j
-
1
)
2
]
,
mod
(
k
,
2
)
≠
mod
(
j
,
2
)
and
∀
k
=
2
N
+
j
~
4
×
N
-
j
-
1
f
4
[
k
-
3
N
]
,
∀
k
=
4
×
N
-
j
~
4
×
N
-
1
where f p represents the frequency modulated signal, f 1 represents the first chirp signal, f 2 represents the second chirp signal, f 3 represents the third chirp signal, f 4 represents the fourth chirp signal, k represents step number.
13. The radar system of claim 10 , wherein the first chirp signal and the second chirp signal are up chirp signals and the third chirp signal and the fourth chirp signal are down chirp signals.
14. The radar system of claim 10 , wherein a frequency shift exists between the maximum frequency of the first and the second chirp signals and the maximum frequency of the third and the fourth chirp signals.
15. The signal generating method of claim 1 , wherein the first chirp signal is generated prior than the second chirp signal in the second duration.
16. The radar system of claim 8 , wherein the first chirp signal is generated prior than the second chirp signal in the second duration.