1. Method for estimating parameters useful to determine the position of a global navigation satellite system (GNSS) receiver or a change in the position of the GNSS receiver, the method including the steps of:
obtaining at least one GNSS signal received at the GNSS receiver from each of a plurality of GNSS satellites;
obtaining, from at least one network node, information, here referred to as \u201cprecise satellite information\u201d, on:
(i) the orbit or position of at least one of the plurality of GNSS satellites, and
(ii) a clock offset of at least one of the plurality of GNSS satellites;
identifying, among the obtained GNSS signals, a subset of at least one GNSS signal possibly affected by a cycle slip, the identified subset being hereinafter referred to as cycle-slip affected subset; and
estimating parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver using
at least some of the obtained GNSS signals which are not in the cycle-slip affected subset, and
the precise satellite information.
2. Method of claim 1, wherein the step of obtaining precise satellite information further includes obtaining information on
(iii) biases between the phase of two or more GNSS signals originating from one satellite, for at least one of the plurality of GNSS satellites.
3. Method of claim 1, wherein the step of obtaining at least one GNSS signal from each of a plurality of GNSS satellites includes
making ranging code observations and carrier phase observations of the GNSS signals.
4. Method of claim 1, wherein the step of obtaining, from at least one network node, precise satellite information includes:
obtaining the information per GNSS satellite at a frequency of 1 Hz or more frequently.
5. Method of claim 4, wherein the step of obtaining, from at least one network node, precise satellite information includes:
obtaining the information per GNSS satellite at a frequency of 2 Hz or more frequently.
6. Method of claim 1, wherein the step of identifying the cycle-slip affected subset includes
detecting cycle slips using at least one of geometry-free carrier phase combinations and geometry-free code-carrier combinations.
7. Method of claim 6, wherein detecting cycle slips using geometry free carrier phase and code-carrier combinations includes
computing geometry-free ionospheric residual carrier phases.
8. Method of claim 6, wherein detecting cycle slips using geometry free carrier phase and code-carrier combinations includes
computing geometry-free Melbourne-Wubbena code-carriers.
9. Method of claim 6, wherein the step of identifying the cycle-slip affected subset makes use of
the obtained precise satellite information.
10. Method of claim 1, wherein the step of estimating parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver includes
determining a position change of the receiver using time-differenced carrier phase for at least some of the obtained GNSS signals which are not in the cycle-slip affected subset.
11. Method of claim 1, wherein the step of estimating parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver makes use of:
at least some of the obtained GNSS signals which are not in the cycle-slip affected subset and which are not originating from a satellite having a clock offset or drift exceeding a threshold based on the specification for the satellite’s atomic clock stability; and
the obtained precise satellite information.
12. Method of claim 1, wherein the step of estimating parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver makes use of:
at least some of the obtained GNSS signals which are not in the cycle-slip affected subset and which are not originating from a satellite that has an abnormal clock offset in the sense that an attempt to compute the clock offset using the broadcast clock parameters results in a residual clock error, when compared to a clock offset computed using the precise satellite information, where said residual clock error exceeds a threshold; and
the obtained precise satellite information.
13. Method of claim 1, wherein the method further includes the steps of:
performing cycle slip fixing on the GNSS signals of the cycle-slip affected subset; and
estimating gain parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver as well as the clock offset of the GNSS receiver by using:
at least some of the obtained GNSS signals including at least one GNSS signal of the cycle-slip affected subset for which cycle slip fixing has been performed; and
the obtained precise satellite information.
14. Method of claim 13, wherein the step of estimating again parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver as well as the clock offset of the GNSS receiver makes use of
ionospheric free code combination and ionospheric free carrier phase combination.
15. Method of claim 13, wherein the step of estimating again parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver as well as the clock offset of the GNSS receiver makes use of:
at least some of the obtained GNSS signals including at least one GNSS signal of the cycle-slip affected subset for which cycle slip fixing has been performed, but not including GNSS signals originating from a satellite having a clock offset or drift exceeding a threshold based on the specification for the satellite’s atomic clock stability; and
the obtained precise satellite information.
16. Method of claim 13, wherein the step of estimating again parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver as well as the clock offset of the GNSS receiver makes use of:
at least some of the obtained GNSS signals including at least one GNSS signal of the cycle-slip affected subset for which cycle slip fixing has been performed, but not including GNSS signals originating from a satellite that has an abnormal clock offset in the sense that an attempt to compute the clock offset using the broadcast clock parameters results in a residual clock error, when compared to a clock offset computed using the precise satellite information, where said residual clock error exceeds a threshold; and
the obtained precise satellite information.
17. Apparatus for estimating parameters useful to determine the position of a global navigation satellite system (GNSS) receiver or a change in the position of the GNSS receiver, the apparatus being configured for:
obtaining at least one GNSS signal received at the GNSS receiver from each of a plurality of GNSS satellites;
obtaining, from at least one network node, information, here referred to as \u201cprecise satellite information\u201d, on:
(i) the orbit or position of at least one of the plurality of GNSS satellites, and
(ii) a clock offset of at least one of the plurality of GNSS satellites;
identifying, among the obtained GNSS signals, a subset of at least one GNSS signal possibly affected by a cycle slip, the identified subset being hereinafter referred to as cycle-slip affected subset; and
estimating parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver using
at least some of the obtained GNSS signals which are not in the cycle-slip affected subset, and
the precise satellite information.
18. Apparatus of claim 17, further configured so that obtaining precise satellite information further includes obtaining information on
(iii) biases between the phase of two or more GNSS signals originating from one satellite, for at least one of the plurality of GNSS satellites.
19. Apparatus of claim 17, further configured so that obtaining, by the GNSS receiver, at least one GNSS signal from each of a plurality of GNSS satellites includes
making ranging code observations and carrier phase observations of the GNSS signals.
20. Apparatus of claim 17, further configured so that obtaining, from at least one network node, precise satellite information includes:
obtaining the information per GNSS satellite at a frequency of 1 Hz or more frequently.
21. Apparatus of claim 20, further configured so that obtaining, from at least one network node, precise satellite information includes:
obtaining the information per GNSS satellite at a frequency of 2 Hz or more frequently.
22. Apparatus of claim 17, further configured so that identifying the cycle-slip affected subset includes
detecting cycle slips using at least one of geometry-free carrier phase combinations and geometry-free code-carrier combinations.
23. Apparatus of claim 22, further configured so that detecting cycle slips using geometry free carrier phase and code-carrier combinations includes
computing geometry-free ionospheric residual carrier phases.
24. Apparatus of claim 22, further configured so that detecting cycle slips using geometry free carrier phase and code-carrier combinations includes
computing geometry-free Melbourne-Wubbena code-carriers.
25. Apparatus of claim 22, further configured so that identifying the cycle-slip affected subset makes use of
the obtained precise satellite information.
26. Apparatus of claim 17, further configured so that estimating parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver includes
determining a position change of the receiver using time-differenced carrier phase for at least some of the obtained GNSS signals which are not in the cycle-slip affected subset.
27. Apparatus of claim 17, further configured so that estimating parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver makes use of:
at least some of the obtained GNSS signals which are not in the cycle-slip affected subset and which are not originating from a satellite having a clock offset or drift exceeding a threshold based on the specification for the satellite’s atomic clock stability; and
the obtained precise satellite information.
28. Apparatus of claim 17, further configured so that estimating parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver makes use of:
at least some of the obtained GNSS signals which are not in the cycle-slip affected subset and which are not originating from a satellite that has an abnormal clock offset in the sense that an attempt to compute the clock offset using the broadcast clock parameters results in a residual clock error, when compared to a clock offset computed using the precise satellite information, where said residual clock error exceeds a threshold; and
the obtained precise satellite information.
29. Apparatus of claim 17, further configured for:
performing cycle slip fixing on the GNSS signals of the cycle-slip affected subset; and
estimating again parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver as well as the clock offset of the GNSS receiver by using:
at least some of the obtained GNSS signals including at least one GNSS signal of the cycle-slip affected subset for which cycle slip fixing has been performed; and
the obtained precise satellite information.
30. Apparatus of claim 18, further configured so that estimating again parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver as well as the clock offset of the GNSS receiver makes use of
ionospheric free code combination and ionospheric free carrier phase combination.
31. Apparatus of claim 29, further configured so that estimating again parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver as well as the clock offset of the GNSS receiver makes use of:
at least some of the obtained GNSS signals including at least one GNSS signal of the cycle-slip affected subset for which cycle slip fixing has been performed, but not including GNSS signals originating from a satellite having a clock offset or drift exceeding a threshold based on the specification for the satellite’s atomic clock stability; and
the obtained precise satellite information.
32. Apparatus of claim 29, further configured so that estimating again parameters useful to determine the position of the GNSS receiver or a change in the position of the GNSS receiver as well as the clock offset of the GNSS receiver makes use of:
at least some of the obtained GNSS signals including at least one GNSS signal of the cycle-slip affected subset for which cycle slip fixing has been performed, but not including GNSS signals originating from a satellite that has an abnormal clock offset in the sense that an attempt to compute the clock offset using the broadcast clock parameters results in a residual clock error, when compared to a clock offset computed using the precise satellite information, where said residual clock error exceeds a threshold; and
the obtained precise satellite information.
33. Rover comprising an apparatus according to claim 17.
34. Network station comprising an apparatus according to claim 17.
35. Computer program comprising computer-readable instructions configured, when executed on a computer, to cause the computer to carry out the method according to claim 1.
36. Computer program product including a computer program according to claim 35.
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. An image forming apparatus which has image recording device to record an image to a sheet, comprising:
a sheet conveying device which conveys a sheet to the image recording device;
a sheet regulating device which has a pair of side regulating plates, and the side regulating plates are brought into contact by a driving device with both side ends of a sheet on which an image is formed by the image recording device and regulates a position of the sheet in a widthwise direction while the image is formed on the sheet; and
a control unit which controls the driving device to move the side regulating plates to positions where the position of the sheet in the widthwise direction is regulated depending on the size of the sheet on which an image is to be formed.
2. The image forming apparatus according to claim 1, further comprising
a sheet width detecting device to detect the size of a sheet in the sheet width direction perpendicular to a conveyance direction of the sheet by the sheet conveying device, and wherein the control unit controls the driving device to move the side regulating plates based on detection performed by the sheet width detecting device.
3. The image forming apparatus according to claim 1, wherein
the image recording device has an image bearing member which bears a toner image and a transfer roller which brings a sheet into contact with the image bearing member and conveys the sheet, and
the sheet regulating device is arranged on an upstream side or a downstream side in a sheet conveyance direction.
4. The image forming apparatus according to claim 1, wherein
a registration device which corrects the position of a sheet to be conveyed is arranged on the upstream side of the image recording device in a sheet conveyance direction, the registration device has a sheet correcting plate and a skew feed roller to bring the sheet into contact with the sheet correcting plate in order to correct skew feeding of the sheet, a registration roller pair which can be reciprocated is arranged to correct the position of the sheet, and the sheet is moved by the reciprocating operation of the registration roller pair such that the sheet is aligned to a regulated position of the sheet width direction regulating device.
5. The image forming apparatus according to claim 4, wherein
a nip of the registration roller pair is released by a nip releasing device when the sheet conveyed by the image recording device is regulated by the sheet regulating device.
6. The image forming apparatus according to claim 2, wherein
the pair of side regulating plates can be separated from each other and contacted to each other, the control unit sets an interval between the side regulating plates based on a size standard value of a conveyed sheet in the width direction, and, depending on information obtained by detecting an actual size of the conveyed sheet in the width direction by the sheet width detecting device, the size regulating plates are moved by a difference between the size standard value and the actual size.
7. The image forming apparatus according to claim 2, wherein
the sheet width detecting device detects a position of the side end of a sheet conveyed by the sheet conveying device in the width direction to detect a size in the sheet width direction.
8. The image forming apparatus according to claim 2, wherein
the sheet width detecting device detects the size of a sheet in the sheet width direction, the sheet being supported on a sheet stacking portion to supported a sheet on which an image is to be formed.
9. The image forming apparatus according to claim 2, wherein
the sheet width detecting device detects the size in the sheet width direction based on information input from an operation panel.
10. The image forming apparatus according to claim 2, wherein
the control unit determines whether a regulating operation in a sheet width direction is performed by the sheet regulating device based on information of sheet rigidity, and the control unit causes the sheet regulating device to perform a regulating operation to a sheet having sheet rigidity which is not less than predetermined sheet rigidity.