1. A strapdown heading sensor, comprising:
an elongated housing; and
a compass module at least partially positioned within an inner cavity of the elongated housing, the compass module including at least one solid state sensor,
wherein the compass module is cantilevered within the inner cavity of the elongated housing.
2. The strapdown heading sensor of claim 1, wherein the compass module is coupled to a surface of the inner cavity of the elongated housing.
3. The strapdown heading sensor of claim 2, wherein a proximal end of the compass module is coupled to a proximal end of the elongated housing, and wherein a distal end of the compass module is suspended within a central region of the inner cavity of the elongated housing.
4. The strapdown heading sensor of claim 2, wherein an end-cap of the compass module is coupled within a proximal end of the elongated housing.
5. The strapdown heading sensor of claim 1, wherein the at least one solid state sensor comprises at least one magnetometer and at least one accelerometer.
6. The strap down heading sensor of claim 5, wherein the at least one magnetometer comprises at least one selected magnetometer of a group consisting of: a uni-axial magnetometer, a bi-axial magnetometer and a tri-axial magnetometer.
7. The strapdown heading sensor of claim 6, wherein the at least one accelerometer comprises at least one selected accelerometer from a group consisting of: a uni-axial accelerometer, a bi-axial accelerometer and a tri-axial magnetometer.
8. A strapdown heading sensor, comprising:
an elongated housing; and
a compass module positioned within an inner cavity of the elongated housing, the compass module including at least one solid state sensor, wherein the compass module is passively isolated from shock or vibrations induced on an outer surface of the elongated housing.
9. The strapdown heading sensor of claim 8, wherein the elongated housing includes a closed housing, and wherein the strapdown heading sensor further comprises an end-cap constructed and arranged to close a single opening of closed housing.
10. The strapdown heading sensor of claim 8, wherein the elongated housing includes an opened housing, and wherein the strapdown heading sensor further comprises a first end-cap constructed and arranged to close a first opening of the opened housing and a second end-cap constructed and arranged to close a second opening of the opened housing.
11. The strapdown heading sensor of claim 8, further comprising a damper positioned between the compass module and a surface of the inner cavity of the elongated housing.
12. The strapdown heading sensor of claim 11, wherein the damper includes a first damper positioned about a proximal end of the compass module and a second damper positioned about a distal end of the compass module.
13. The strapdown heading sensor of claim 12, wherein the damper further includes a first bumper positioned at the proximal end of the compass module and a second bumper positioned at the distal end of the compass module.
14. A method of calibrating a strapdown heading sensor, comprising:
compensating raw sensor data generated by sensors of an uncalibrated strapdown heading sensor to compensate for errors in an instrument frame of the strapdown heading sensor;
providing the strapdown heading sensor in a target apparatus; and
after providing the strapdown heading sensor in the target apparatus, compensating output data of the strapdown heading sensor to compensate for errors in an apparatus frame of the target apparatus relative to the instrument frame of the strapdown heading sensor,
wherein the strapdown heading sensor comprises
an elongated housing; and
a compass module at least partially positioned within an inner cavity of the elongated housing, the compass module including at least one solid state sensor,
wherein the compass module is cantilevered within the inner cavity of the elongated housing.
15. The method of claim 14, wherein the errors in the instrument frame of the strap down heading sensor include at least one of: a misalignment of the sensors mounted within a housing of the strapdown heading sensor, an intra-sensor nonorthogonal error, an inter-sensor nonorthogonal error, a gain error, a bias error and hardsoft iron errors of the sensors of the strapdown heading sensor.
16. The method of claim 14, wherein the errors in the apparatus frame of the strapdown heading sensor include at least one of: a misalignment of the sensors mounted within a housing of the strapdown heading sensor, a misalignment of the strapdown heading sensor mounted within the target apparatus, an intra-sensor nonorthogonal error, an inter-sensor nonorthogonal error, a gain error, a bias error and hardsoft iron errors of the sensors of the strapdown heading sensor.
17. The method of claim 14, wherein compensating raw sensor data generated by sensors of an uncalibrated strapdown heading sensor includes:
applying test conditions to the uncalibrated strapdown sensor;
computing compensation coefficients based on raw sensor data generated by the uncalibrated strapdown sensor and reference data determined from a known reference source; and
compensating the raw sensor data so that compensated sensor data generated by the strapdown heading sensor corresponds to a physical orientation of the strapdown heading sensor.
18. The method of claim 17, wherein the known reference source is generated by a reference sensor.
19. The method of claim 17, wherein applying test conditions to the uncalibrated strapdown sensor includes at least one of: varying a temperature of the uncalibrated strapdown sensor, varying an orientation of the uncalibrated strapdown sensor, varying magnetic fields applied to the uncalibrated strapdown sensor and altering a position of the uncalibrated strapdown heading sensor so as to affect a gravitational field applied to the uncalibrated strapdown sensor.
20. The method of claim 17, further comprising:
converting the compensated sensor data in the instrument frame of the strapdown heading sensor to compensated sensor data in the Earth’s frame relative to the strapdown heading sensor; and
outputting compensated sensor data in the Earth’s frame relative to the strapdown heading sensor.
21. The method of claim 14, wherein providing the strapdown heading sensor in a target apparatus introduces the errors in the apparatus frame relative to the strapdown heading sensor.
22. The method of claim 14, wherein compensating output data of the strapdown heading sensor includes:
applying test conditions to the strapdown sensor provided in the target apparatus;
computing compensation coefficients based on sensor data generated by the strapdown sensor and reference data determined from a known reference source; and
compensating the sensor data so that compensated sensor data generated by the strapdown heading sensor corresponds to a physical orientation of the target apparatus.
23. The method of claim 22, wherein applying test conditions to the strapdown sensor provided in the target apparatus includes at least one of: varying a temperature of the strapdown sensor, varying an orientation of the uncalibrated strapdown sensor, varying magnetic fields applied to the uncalibrated strapdown sensor and altering a position of the uncalibrated strapdown heading sensor so as to affect a gravitational field applied to the uncalibrated strapdown sensor.
24. The method of claim 22, wherein the known reference source is generated by a reference sensor.
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 optical device comprising:
a drop optical multicast switch unit, comprising:
a plurality of input optical ports,
a plurality of optical splitters, each optical splitter coupled to a corresponding input optical port,
a plurality of optical switches, each optical switch coupled to each optical splitter of the plurality of optical splitters, and
a plurality of output optical ports; and
an add optical multicast switch unit, comprising;
a plurality of input optical ports;
a plurality of optical switches, each optical switch coupled to a corresponding input optical port;
a plurality of optical combiners, each optical combiner coupled to each optical switch of the plurality of optical switches, and
a plurality of output optical ports coupled to a corresponding optical combiner.
2. The optical device of claim 1, wherein the first optical multicast switch unit and the second optical multicast switch unit are symmetrical.
3. The optical device of claim 1, wherein the first optical multicast switch unit is N\xd7M and second optical multicast switch unit is A\xd7B, where N\xd7M is distinct from A\xd7B.
4. The optical device of claim 1, wherein the optical switches are micro-electro-mechanical-systems (MEMS) based optical switches.
5. The optical device of claim 1, wherein the plurality of optical switches in first optical multicast switch unit comprises L\xd71 selectors, wherein L\u2267N.
6. The optical device of claim 5, wherein extra input ports (L\u2212N) of the L\xd71 selectors of the plurality of optical switches are reserved as expansion ports.
7. The optical device of claim 1, wherein an input optical signal at a first optical input port of the first optical multicast switch unit is split into M portions by a corresponding optical splitter and distributed to each of the plurality of optical switches.
8. The optical device of claim 1, wherein each optical switch of the plurality of optical switches in the first optical multicast switch unit receives an input from each input optical port and selects one to output to an output optical port.
9. The optical device of claim 1, wherein an input optical signal at a first optical input port of the second optical multicast switch unit is input to a first switch of the plurality of optical switches, wherein the first switch is coupled to each of the plurality of optical combiners such that the first switch can pass the input optical signal to any one of the plurality of optical combiners.
10. A twin multicast switch module comprising:
a first multicast switch unit; and
a second multicast switch unit,
wherein each of the first and second multicast switch units respectively comprises:
a plurality of optical input ports;
a plurality of optical switches;
a plurality of optical splitterscombiners; and
a plurality of optical output ports.
11. The twin multicast switch module of claim 10, wherein the first multicast switch unit is a drop unit and the second multicast switch unit is an add unit.