1. A hydraulic transaxle comprising:
a transaxle housing defining a fluid sump therein;
an axle supported by the transaxle housing;
a hydraulic motor disposed in the transaxle housing so as to drive the axle;
a hydraulic pump disposed in the transaxle housing so as to supply hydraulic fluid to the hydraulic motor;
a hydraulic circuit disposed in the transaxle housing so as to fluidly connect the hydraulic pump to the hydraulic motor; and
a pair of auxiliary pumps disposed in the transaxle housing so as to supply fluid from the fluid sump to outside of the transaxle housing.
2. The hydraulic transaxle according to claim 1, wherein the hydraulic transaxle serves as a first hydraulic transaxle,
wherein one of the auxiliary pumps serves as a charge pump for supplying fluid from the fluid sump in the transaxle housing of the first hydraulic transaxle into a transaxle housing of a second hydraulic transaxle, and
wherein the other of the auxiliary pumps serves as an actuator pump for supplying fluid from the fluid sump in the transaxle housing of the first hydraulic transaxle to a hydraulic actuator disposed outside of the transaxle housings of the first and second hydraulic transaxles.
3. The hydraulic transaxle according to claim 2, wherein a vehicle is equipped with the first and second hydraulic transaxles and a mower deck, and
wherein the hydraulic actuator is provided for lifting the mower deck.
4. The hydraulic transaxle according to claim 2, further comprising:
a hydraulic valve disposed outside of the transaxle housings of the first and second hydraulic transaxles so as to fluidly connect the hydraulic actuator to the actuator pump.
5. The hydraulic transaxle according to claim 4, wherein the transaxle housing of the second hydraulic transaxle defines a fluid sump therein, and
wherein the hydraulic valve is fluidly connected to the fluid sump in the transaxle housing of the second hydraulic transaxle.
6. The hydraulic transaxle according to claim 1, further comprising:
a pump housing supporting the auxiliary pumps,
wherein the pump housing includes a suction duct and a pair of delivery ducts, and
wherein the pump housing is disposed in the transaxle housing so as to supply fluid from the fluid sump to the auxiliary pumps via the suction duct, and so as to deliver fluid from the auxiliary pumps to the outside of the transaxle housing via the respective delivery ducts.
7. The hydraulic transaxle according to claim 6, wherein the suction duct serves as a first suction duct, and
wherein the pump housing has a second suction duct fluidly connected to the hydraulic circuit so as to supply fluid from the outside of the transaxle housing to the hydraulic circuit.
8. The hydraulic transaxle according to claim 7, wherein the hydraulic transaxle serves as a first hydraulic transaxle,
wherein one of the auxiliary pumps serves as a charge pump for supplying fluid from the fluid sump in the transaxle housing of the first hydraulic transaxle into a transaxle housing of a second hydraulic transaxle via one of the delivery ducts,
wherein the other of the auxiliary pumps serves as an actuator pump for supplying fluid from the fluid sump in the transaxle housing of the first hydraulic transaxle to a hydraulic actuator disposed outside of the transaxle housings of the first and second hydraulic transaxles via the other of the delivery ducts, and
wherein the second suction duct is fluidly connected to the transaxle housing of the second hydraulic transaxle so as to supply fluid from the transaxle housing of the second hydraulic transaxle to the hydraulic circuit in the transaxle housing of the first hydraulic transaxle.
9. The hydraulic transaxle according to claim 8, further comprising:
a center section having the hydraulic pump and the hydraulic motor mounted thereon so as to define the hydraulic circuit between the hydraulic pump and the hydraulic motor,
wherein the center section is disposed in the transaxle housing of the first hydraulic transaxle and is connected to the pump housing so as to fluidly connect the hydraulic circuit to the second suction duct.
10. The hydraulic transaxle according to claim 6, wherein an input shaft of the hydraulic pump is extended into the pump housing so as to drive the auxiliary pumps.
11. The hydraulic transaxle according to claim 10, wherein the auxiliary pumps are disposed opposite each other in an axial direction of the input shaft of the hydraulic pump, and
wherein the suction duct has an opening that opens outward to the fluid sump at a position on the pump housing between the auxiliary pumps in the axial direction of the input shaft of the hydraulic pump, and bifurcates in the pump housing to the auxiliary pumps.
12. The hydraulic transaxle according to claim 10, wherein the suction duct has an opening at a side of the pump housing, and
wherein the delivery ducts have respective openings at another side of the pump housing opposite to the suction duct with respect to the input shaft of the hydraulic pump.
13. The hydraulic transaxle according to claim 6, the pump housing serving as a first pump housing, further comprising:
a second pump housing disposed in the transaxle housing so as to have one of the auxiliary pumps mounted thereon, wherein the second pump housing is movable away from the auxiliary pump mounted on the second pump housing according to an increase of a pressure of fluid delivered from the auxiliary pump mounted on the second pump housing; and
a biasing member disposed in the transaxle housing so as to bias the second pump housing toward the auxiliary pump mounted on the second pump housing against the pressure of fluid delivered from the auxiliary pump mounted on the second pump housing.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for generating comfort noise, the method comprising:
obtaining a sample of background noise and voice communications of at least two users in a time domain at a communication device, wherein the communication device is used to transmit and receive the voice communications between the at least two users;
filtering the voice communications from the sample of background noise and voice communications to obtain a filtered sample of background noise;
converting, by the communication device, the filtered sample of background noise, without converting the voice communications of the at least two users, from the time domain to a frequency domain, thereby creating a background noise spectrum in the frequency domain; and
multiplying, by the communication device, the background noise spectrum in the frequency domain by a random white noise spectrum, thereby creating a comfort noise spectrum in the frequency domain.
2. A non-transitory computer readable medium having stored therein instructions for causing a processor to execute the method of claim 1.
3. The method of claim 1, further comprising converting the comfort noise spectrum in the frequency domain to the time domain.
4. The method of claim 3, wherein an inverse Discrete Fourier Transform is used to convert the comfort noise spectrum in the frequency domain to the time domain.
5. The method of claim 3, further comprising scaling a power level of the comfort noise in the time domain to approximately match a power level of the sample of the background noise in the time domain.
6. The method of claim 1, wherein converting the sample of background noise from the time domain to a frequency domain comprises performing a Fourier Transform on the sample of background noise in the time domain.
7. The method of claim 1, wherein the sample of the background noise in the time domain is given by h(k) with 0<=k<N and wherein N is between 80 and 256 inclusive, and wherein converting the sample of background noise from the time domain to a frequency domain comprises taking the N-point Discrete Fourier Transform (\u201cDFT\u201d) of h(k).
8. The method of claim 1, wherein converting the sample of background noise from the time domain to a frequency domain comprises performing a cosine transform or a sine transform on the sample of background noise in the time domain.
9. The method of claim 8, wherein the sample of the background noise in the time domain is given by h(k) with 0<=k<N and wherein N is between 80 and 256 inclusive, wherein the background noise spectrum in the frequency domain is given by Y(m), and wherein performing the cosine transform on the sample of background noise in the time domain comprises performing the cosine transform on h(k) according to the formula
Y
\u2061
(
m
)
–
2
N
\u2062
\u2211
k
=
0
N
–
1
\u2062
h
\u2061
(
k
)
\u2062
cos
(
\u03c0
\u2062
\u2062
(
k
+
0.5
)
\u2062
(
m
+
0.5
)
N
so as to obtain Y(m).
10. The method of claim 8, further comprising performing an inverse cosine transform or an inverse sine transform on the comfort noise spectrum in the frequency domain so as to convert the comfort noise spectrum to the time domain.
11. The method of claim 1, wherein obtaining the sample of background noise in a time domain comprises sampling, at a sampling rate of at least 8000 Hz, a signal on a voice connection currently established between two devices.
12. A method for generating comfort noise, the method comprising:
filtering voice communication from background noise to obtain a background noise segment in a time domain at a communication device;
obtaining a random noise segment in the time domain at the communication device; and
generating, by the communication device, a comfort noise segment in the time domain by convolving the background noise segment and the random noise segment.
13. A non-transitory computer readable medium having stored therein instructions for causing a processor to execute the method of claim 12.
14. The method of claim 12, wherein n(k) represents the random noise segment, wherein h(i) represents the background noise segment, wherein x(n) represents the comfort noise segment, and wherein the x(n) is obtained according to the formula
x
\u2061
(
n
)
=
\u2211
i
=
0
N
–
1
\u2062
h
\u2061
(
i
)
\u2062
n
\u2061
(
k
–
i
)
.
15. The method of claim 12, wherein obtaining a random noise segment in the time domain comprises converting the random noise segment to a random pulse sequence.
16. The method of claim 12, wherein obtaining a random noise segment in the time domain comprises converting the random noise segment to a random pulse sequence according to the formula
r
\u2061
(
k
)
=
\u2211
i
=
0
\u221e
\u2062
n
\u2061
(
i
)
\u2062
\u03b4
\u2061
(
k
–
iM
i
)
,
wherein n(i) represents the random noise segment and r(k) represents the random pulse sequence, and wherein {Mi} defines pulse positions and is a sequence of integers such that 0<Mi<N.
17. The method of claim 16, wherein {Mi} is chosen so as to substantially minimize artificial harmonics.
18. The method of claim 16, wherein generating a comfort noise segment in the time domain by convolving the background noise segment and the random noise segment comprises generating the comfort noise segment in the time domain by convolving the background noise segment with the random pulse sequence.
19. The method of claim 16, wherein generating a comfort noise segment in the time domain by convolving the background noise segment and the random noise segment comprises generating the comfort noise segment in the time domain by convolving the background noise segment with the random pulse sequence according to the formula
x
\u2061
(
k
)
=
\u2211
i
=
0
\u221e
\u2062
n
\u2061
(
i
)
\u2062
h
\u2061
(
n
–
iM
i
)
.
20. A device for voice communications between at least two users, the device including:
a processor;
a memory; and
code stored in the memory and executable on the processor to:
obtain a sample of background noise and voice communications of the at least two users in a time domain,
filter the voice communications from the sample of background and voice communications to obtain a filtered sample of background noise,
convert the filtered sample of background noise, without converting the voice communications of the at least two users, from the time domain to a frequency domain, thereby creating a background noise spectrum in the frequency domain,
multiply the background noise spectrum in the frequency domain by a random white noise spectrum, thereby creating a comfort noise spectrum in the frequency domain,
convert the comfort noise spectrum in the frequency domain to a time domain, and
output the comfort noise to a user of the device.