Optimized chirp signal shaping for ultrasonic sensing systems
A method to operate an ultrasonic sensor includes the step of sending an ultrasonic burst as a series of ultrasonic pulses that have a pulse length and a pulse spacing. The sum of the pulse length and pulse spacing represents the pulse period length. The ultrasonic burst starts at a first time and ends at a second time. The current pulse frequency corresponds to an inverse of the current pulse length. The current pulse frequency, during a first time period passes through a first frequency range, in a following middle time period a middle frequency range and in a following second time period a second frequency range. The length of time of the middle time period is equal to or longer than the sum of the first time period and the second time period.
1. A method for operating an ultrasonic sensor, comprising:
transmitting a total ultrasonic burst as a direct temporal succession of transmissions of partial ultrasonic bursts,
wherein at least the transmission of a partial ultrasonic burst of these partial ultrasonic bursts comprising transmitting the partial ultrasonic burst as a series of ultrasonic pulses that have a pulse length (T 1 ) and a pulse spacing (T 2 ),
wherein the pulse length (T 1 ) and the pulse spacing (T 2 ) combined equal a pulse period length (T=T 1 +T 2 ), and
wherein the partial ultrasonic burst starts at a first time (t 1 ) and ends at a second time (t 2 ), and
wherein a current pulse frequency (f m,NL =1/T) corresponds to an inverse of the pulse period length (T),
and wherein a first respective pulse period length (T) and therefore a first respective current pulse frequency (f m,NL =1/T) at the first time (t 1 ) is different than a second respective pulse period length (T) and therefore a second respective current pulse frequency (f m,NL =1/T) at the second time (t 2 ),
wherein a change in the current pulse frequency
(
∂
f
m
,
NL
∂
t
)
at at least a third time (t 3 ) between the first time (t 1 ) and the second time (t 2 ) is different than a change in the current pulse frequency
(
∂
f
m
,
NL
∂
t
)
at at least a fourth time (t 4 ) between the first time (t 1 ) and the second time (t 2 ), and
wherein a change in the current pulse frequency
(
∂
f
m
,
NL
∂
t
)
between consecutive pulses at a center frequency of the total ultrasonic burst is less than a change of the current pulse frequency
(
∂
f
m
,
NL
∂
t
)
between an initial pulse in the total ultrasonic burst and a consecutive second pulse at a beginning of the total ultrasonic burst and less than a change of the current pulse frequency
(
∂
f
m
,
NL
∂
t
)
between a next-to-last pulse in the total ultrasonic burst and a consecutive last pulse at an end of the total ultrasonic burst.
2. A method for operating an ultrasonic sensor, comprising:
transmitting an ultrasonic burst as a series of ultrasonic pulses with a pulse length (T 1 ) and a pulse spacing (T 2 ),
wherein a sum of the pulse length (T 1 ) and the pulse spacing (T 2 ) represent a pulse period length (T=T 1 +T 2 ), and
wherein the ultrasonic bursts starts at a first time (t 1 ) and ends at a second time (t 2 ), and
wherein a current pulse frequency (f m,NL (t)) is described with the equation
f
m
,
NL
(
t
)
=
t
T
(
B
L
+
B
C
1
1
-
4
t
2
T
2
)
where t is time and T is the pulse period length, and
wherein B L is a coefficient of a bandwidth for a linear portion and B C , is a coefficient of the bandwidth for a non-linear portion.
3. The method according, to claim 2 ,
wherein a current pulse frequency change
(
∂
f
m
,
NL
∂
t
)
between the first time (t 1 ) and the second time (t 2 ) decreases or increases monotonically.
4. The method according, to claim 2 ,
wherein a temporal change of a current pulse frequency change
(
∂
2
f
m
,
NL
∂
t
2
)
between the first time (t 1 ) and the second time (t 2 ) decreases or increases monotonically.
5. The method according to claim 2 ,
wherein a temporal change of the current pulse frequency change
(
∂
2
f
m
,
NL
∂
t
2
)
between the first time (t 1 ) and the second time (t 2 ) at at least a time t 3 , where t 1 <t 3 <t 2 is constant, such that
(
∂
2
f
m
,
NL
∂
t
3
=
0
)
amines at t 3 .
6. A method for operating an ultrasonic sensor, comprising:
transmitting a total ultrasonic burst as a direct temporal sequencing of transmissions of sub-ultrasonic bursts,
wherein at least the transmission of one sub-ultrasonic burst of these sub-ultrasonic bursts corresponds to the method according to claim 2 .
7. A method for operating an ultrasonic sensor, comprising
transmitting a total ultrasonic burst as a direct temporal succession of transmissions of partial ultrasonic bursts,
wherein at least the transmission of a partial ultrasonic burst of these partial ultrasonic bursts comprises transmitting a partial ultrasonic burst as a series of ultrasonic pulses that have a pulse length (T 1 ) and a pulse spacing (T 2 ),
wherein the pulse length (T 1 ) and the pulse spacing (T 2 ) combined equal a pulse period length (T=T 1 ±T 2 ), and
wherein the partial ultrasonic burst starts at a first time (t 1 ) and ends at a second time (t 2 ), and
wherein the partial ultrasonic burst has a temporal ultrasonic burst length (Δt s =t 2 −t 1 ), and
wherein the current pulse frequency (f m,NL =|1/T|) corresponds to an inverse of the current pulse period length (T) at a time (t) during the partial ultrasonic burst (t 1 ≤t≤t 2 ), and
wherein the pulse period length (T), and therefore the current pulse frequency (f m,NL =|1/T|) at the first time (t 1 ), is then referred to as a first current pulse frequency (f u ), and
wherein the pulse period length (T), and therefore the current pulse frequency (f m,NL =|1/T|) at the second time (t 2 ), is then referred to as a second current pulse frequency (f 1 ), and
wherein the first current pulse frequency (f u ) is different than the second current pulse frequency (f 1 ), and
wherein the partial ultrasonic burst has a middle current pulse frequency (f c =|f u −f 1 |/2), and
wherein a total change in the current pulse frequency (f m,NL =|1/T|) between the first time (t 1 ) and the second time (t 2 ) is then referred to as the total change in frequency (Δf s ), and
wherein the first boundary frequency (f cu ) is the frequency that has a frequency spacing to the first current pulse frequency (f u ) that is one half of the frequency spacing to the second current pulse frequency (f 1 ), and
wherein the second boundary frequency (f c1 ) is the frequency that has a frequency spacing to the second current frequency (f 1 ) that is one half of the frequency spacing to the first current pulse frequency (f u ), and
wherein the current pulse frequency (f m,NL ) at a first boundary time (t cu ) equals the first boundary frequency (f cu ), and
wherein the current pulse frequency (f m,NL ) at a second boundary time (t cu ) equals the second boundary frequency (f cu ), and
wherein the first boundary time (t cu ) follows the first time (t 1 ), and
wherein the second boundary time (f c1 ) follows the first boundary time (t cu ), and
wherein the second time (t 2 ) follows the second boundary time (t c1 ), and
wherein the current pulse frequency (f m,NL ) during a first time period (Δt u ), which starts at the first time (t 1 ) and ends at the first boundary time (t cu ), is located between the first current pulse frequency (f u ) and the first boundary frequency (f cu ) in a first frequency range (Δf u ) between the first current pulse frequency (f u ) and the first boundary frequency (f cu ), and
wherein the current pulse frequency (f m,NL ) during a middle time period (Δt c ), which starts at the first boundary time (t cu ) and ends at the second boundary time (t c1 ), is located between the first boundary frequency (f cu ) and the second boundary frequency (f c1 ) in a middle frequency range (Δf c ) between the first boundary frequency (f cu ) and the second boundary frequency (f c1 ), and
wherein the current pulse frequency (f m,NL ) during a second time period (Δt 1 ), which begins at the second boundary time (t c1 ) and ends at the second time (t 2 ), is located between the second boundary frequency (f c1 ) and the second current pulse frequency (f 1 ) in a second frequency range (Δf 1 ) between the first current pulse frequency (f u ) and the first boundary frequency (f cu ), and
wherein the length of the middle time period (Δt c ) is greater than the sum of the length of the first time period (Δt u ) and the length of the second time period (Δt 1 ), or wherein the length of the middle time period (Δt c ) equals the sum of the length of the first time period (Δt u ) and the length of the second time period (Δ 1 ).
8. A method for operating an ultrasonic sensor, comprising the steps
transmitting an ultrasonic burst as a series of ultrasonic pulses that have a pulse length (T 1 ) and a pulse spacing (T 2 ),
wherein the sum of the pulse length (T 1 ) and pulse spacing (T 2 ) represents the pulse period length (T=T 1 +T 2 ), and
wherein the ultrasonic burst starts at a first time (t 1 ) and ends at a second time (t 2 ), and
wherein the ultrasonic burst has a temporal ultrasonic burst length (Δt s =t 2 −t 1 ), and
wherein a current pulse frequency (f m,NL =|1/T|) corresponds to an inverse of the current pulse period length (T) at a time (t) during the ultrasonic burst (t 1 ≤t≤t 2 ), and
wherein the pulse period length (T), and thus the current pulse frequency (f m,NL =|1/T|) at the first time (t 1 ) is referred to below as a first current pulse frequency (f u ), and
wherein the pulse period length (T), and thus the current pulse frequency (f m,NL =|1/T|) at the second time (t 2 ) is referred to below as a second current pulse frequency (f l ), and
wherein the first current pulse frequency (f u ) differs from the second current pulse frequency (f l ), and
wherein the ultrasonic burst has a middle current pulse frequency (f c =|f u +f l |/2), and
wherein a total change in the current pulse frequency (f m,NL =|1/T|) between the first time (t 1 ) and the second time (t 2 ) is referred to as the total frequency change (Δf s ), and
wherein a first boundary frequency (f cu ) is a first frequency, a first frequency spacing to the current pulse frequency (f u ) of which is one half of a second frequency spacing to the second current pulse frequency (f l ), and
wherein a second boundary frequency (f cl ) is a second frequency, a third frequency spacing to the current pulse frequency (f l ) of which is one half of a fourth frequency spacing to the first current pulse frequency (f u ), and
wherein a current pulse frequency (f m,NL ) at a first boundary time (t cu ) is the same as the first boundary frequency (f cu ), and
wherein the current pulse frequency (f m,NL ) at a second boundary time (t cl ) is the same as the second boundary frequency (f cl ), and
wherein the first boundary time (t cu ) follows the first time (t 1 ), and
wherein the second boundary time (t cl ) follows the first boundary time (t cu ), and
wherein the current pulse frequency (f m,NL ) during a first time period (Δt u ), starting at the first time (t 1 ) and ending at the first boundary time (t cu ), is located between the first current pulse frequency (f u ) and the first boundary frequency (f cu ) in a first frequency range (Δf u ) between the first current pulse frequency (f u ) and the first boundary frequency (f cu ), and
wherein the current pulse frequency (f m,NL ) during a middle time period (Δt u ), which starts at the first boundary time (t cu ) and ends at the second boundary time (t cl ), is located between the first boundary frequency (f cu ) and the second boundary frequency (f cl ) in a middle frequency range (Δf c ), and
wherein the current pulse frequency (f m,NL ) during a second time period (Δt 1 ), which starts at the second boundary time (t cl ) and ends at the second time (t 2 ), is located between the second boundary frequency (f c1 ) and the second current pulse frequency (f l ) in a second frequency range (Δf 1 ) between the first current pulse frequency (f u ) and the first boundary frequency (f cu ), and
wherein a length of the middle time period (Δt c ) is greater than a sum of a length of the first time period (Δt u ) and a length of the second time period (Δt 1 ), or wherein the length of the middle time period (Δt c ) equals the sum of the length of the first time period (Δt u ) and the length of the second time period (Δt 1 ) and wherein the current pulse frequency (f m,NL (t)) is described with the equation
f
m
,
NL
(
t
)
=
t
T
(
B
L
+
B
C
1
1
-
4
t
2
T
2
)
wherein B L is a coefficient of a bandwidth for a linear portion and B C is a coefficient of the bandwidth for a non-linear portion.
9. A method for operating an ultrasonic sensor, comprising:
transmitting a total ultrasonic burst as a temporally direct sequencing of transmission of sub-ultrasonic bursts,
wherein at least the transmission of one of the sub-ultrasonic bursts of these sub-ultrasonic bursts corresponds to the method according to claim 8 .