1. A vehicle turn monitoring method comprising:
determining with a controller an intent for a host vehicle to execute a left turn before the host vehicle begins to execute the left turn;
monitoring with the controller a location relationship between the host vehicle and a remote vehicle before the host vehicle begins to execute the left turn, the location relationship including a straight line between the host vehicle location and the remote vehicle location, and an angle between the host vehicle heading and the straight line based on a fixed coordinate system and a preselected angle direction;
evaluating with the controller a travelling condition of the host vehicle before the host vehicle begins to execute the left turn; and
determining with the controller whether to perform a threat mitigation operation before the host vehicle begins to execute the left turn based on the location relationship and the travelling condition.
2. The vehicle turn monitoring method according to claim 1, wherein
the evaluating of the travelling condition includes determining a speed of the host vehicle before the host vehicle begins to execute the left turn.
3. The vehicle turn monitoring method according to claim 2, wherein
the determining of the speed includes determining whether the host vehicle is moving, and while the host vehicle is moving determining whether the speed of the host vehicle is between two speed thresholds.
4. The vehicle turn monitoring method according to claim 1, wherein
the evaluating of the travelling condition includes monitoring an acceleration of the host vehicle before the host vehicle begins to execute the left turn.
5. The vehicle turn monitoring method according to claim 4, wherein
the monitoring of the acceleration includes determining whether the host vehicle is moving, and while the host vehicle is moving determining whether the acceleration of the host vehicle is between two acceleration thresholds.
6. The vehicle turn monitoring method according to claim 1, wherein
the monitoring of the location relationship includes determining a time to contact between the host vehicle and a remote vehicle.
7. The vehicle turn monitoring method according to claim 6, wherein
the monitoring of the location relationship includes determining whether the time to contact is below a contact threshold time.
8. The vehicle turn monitoring method according to claim 1, wherein
the evaluating of the travelling condition includes determining a speed of the host vehicle and monitoring an acceleration of the host vehicle.
9. The vehicle turn monitoring method according to claim 8, wherein
the determining whether to perform the threat mitigation operation determines to perform the threat mitigation operation while the location relationship indicates a time of contact between the host vehicle and the remote vehicle that is below a threshold contact time, and the speed of the host vehicle and the acceleration of the host vehicle are within respective threshold ranges.
10. The vehicle turn monitoring method according to claim 1, wherein
the determining of the intent includes determining the intent for the host vehicle to execute the left turn based on a condition of a turn signal of the host vehicle.
11. The vehicle turn monitoring method according to claim 1, wherein
the monitoring of the location relationship includes monitoring respective locations of the host vehicle and a remote vehicle in relation to an intersection.
12. The vehicle turn monitoring method according to claim 1, further comprising
performing the threat mitigation operation upon the determining of whether to perform a threat mitigation operation determines to perform the threat mitigation operation.
13. The vehicle turn monitoring method according to claim 12, wherein
the performing of the threat mitigation operation includes providing a warning at the host vehicle.
14. The vehicle turn monitoring method according to claim 12, wherein
the performing of the threat mitigation operation includes altering a speed of the host vehicle.
15. A vehicle turn monitoring system comprising:
a location monitor configured to monitor a location of a host vehicle;
a sensor configured to sense a travelling condition of the host vehicle; and
a controller configured to determine an intent for a host vehicle to execute a left turn before the host vehicle begins to execute the left turn, monitor a location relationship between the host vehicle and a remote vehicle based on the location of the host vehicle as determined by the location monitor before the host vehicle begins to execute the left turn, the location relationship including a straight line between the host vehicle location and the remote vehicle location, and an angle between the host vehicle heading and the straight line based on a fixed coordinate system and a preselected angle direction, evaluate the travelling condition of the host vehicle as sensed by the sensor before the host vehicle begins to execute the left turn, and determine whether to perform a threat mitigation operation before the host vehicle begins to execute the left turn based on the location relationship and the travelling condition.
16. The vehicle turn monitoring system according to claim 15, wherein
the controller is configured to evaluate the travelling condition of the host vehicle by determining whether the host vehicle is moving, and while the host vehicle is moving determining whether a speed of the host vehicle is between two speed thresholds.
17. The vehicle turn monitoring system according to claim 15, wherein
the controller is configured to evaluate the travelling condition of the host vehicle by determining whether the host vehicle is moving, and while the host vehicle is moving determining whether an acceleration of the host vehicle is between two acceleration thresholds.
18. The vehicle turn monitoring system according to claim 15, wherein
the controller is configured to determine to perform the threat mitigation operation while the location relationship indicates a time of contact between the host vehicle and the remote vehicle that is below a threshold contact time, and a speed of the host vehicle and an acceleration of the host vehicle are within respective threshold ranges before the host vehicle begins to execute the left turn.
19. The vehicle turn monitoring system according to claim 15, wherein
the controller is configured to determine the intent for the host vehicle to execute the left turn based on a condition of a turn signal of the host vehicle.
20. The vehicle turn monitoring system according to claim 15, wherein
the controller is configured, upon determining to perform the threat mitigation operation, to control at least one of a warning device to issue a warning at the host vehicle and a vehicle speed control device to change a speed of the host vehicle.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A system, comprising:
a polarization-mode dispersion (PMD) compensator operable to guide a plurality of wavelength-division multiplexed (WDM) optical channels through a common optical path to modify a differential group delay (DGD) in each channel, said PMD compensator operable to adjust said DGD in response to a control signal; and
a feedback control coupled to measure a property of said channels as a whole and operable to generate said control signal according to said property.
2. The system as in claim 1, wherein said property includes an AC electrical power proportional to a current or voltage that represents a total optical power of said channels.
3. The system as in claim 2, wherein said feedback control adjusts said PMD compensator to increase said AC electrical power.
4. The system as in claim 1, wherein said PMD compensator includes a polarization controller operable to adjust an output polarization in response to said control signal, and a polarization-maintaining fiber.
5. The system as in claim 1, wherein said PMD compensator includes a plurality of units connected in series, each unit including a polarization controller operable to adjust an output polarization in response to said control signal and a polarization-maintaining fiber.
6. The system as in claim 1, wherein said feedback control includes:
an optical coupler disposed to couple a portion of an output signal from said PMD compensator that combines said channels;
an optical detector to convert said portion into an electrical signal;
an electrical power detector to detect an AC power of said electrical signal; and
a control circuit to generate said control signal to increase said AC power.
7. The system as in claim 6, wherein said electrical power detector includes an electrical bandpass filter to select said AC power in a frequency band to increase response sensibility of said feedback control.
8. The system as in claim 6, wherein said electrical power detector includes at least two electrical bandpass filters with different frequency bands to select said AC power in one of said frequency bands to increase response sensibility of said feedback control.
9. A method, comprising:
directing each of a plurality of wavelength-division multiplexed (WDM) optical channels through a common optical path to modify a differential group delay (DGD) in each channel so as to produce an output with modified WDM channels;
measuring power of an AC portion of said output; and
modifying the DGD to increase said power.
10. The method as in claim 9, wherein said modification includes adjusting a polarization of each channel relative to a principal axis of a polarization-maintaining fiber in said common optical path.
11. The method as in claim 9, further comprising:
filtering said power in frequency to select a portion of said power in a selected frequency band; and
wherein the DGD is modified to increase said portion in said selected frequency band.
12. The method as in claim 9, further comprising:
filtering said power in frequency to select a first portion of said power in a first selected frequency band;
filtering said power in frequency to select a second portion of said power in a second selected frequency band; and
selecting one of said first and said portions to be increased by modifying the DGD.
13. The method as in claim 9, wherein said measuring power of said AC portion of said output includes:
tapping an output of said common optical path to produce an optical monitor signal;
converting said optical monitor signal into an electrical signal;
measuring an AC electrical power of said electrical signal; and
filtering said AC electrical power in frequency to produce said AC portion.
14. The method as in claim 9, wherein said common optical path includes a first optical polarization controller and a first polarization-maintaining fiber, and wherein said first optical polarization controller is adjusted to modify the DGD.
15. The method as in claim 9, wherein said common optical path includes a plurality of pairs of a polarization controller and a polarization-maintaining fiber connected in series, wherein each optical polarization controller is adjusted to modify the DGD.
16. A system, comprising:
a polarization-mode dispersion (PMD) compensator operable to guide a plurality of wavelength-division multiplexed (WDM) optical channels through a common optical path to modify a differential group delay (DGD) in each channel, said common optical path comprising a plurality of adjustable units connected in series respectively operable to adjust the DGD in response to a plurality of control signals, respectively; and
a feedback control coupled to measure a property of said channels as a whole after transmitting through said common optical path and operable to generate said control signals according to said property.
17. The system as in claim 16, wherein each adjustable unit includes a polarization controller operable to adjust an output polarization in response to a respective control signal and a polarization-maintaining fiber.
18. The system as in claim 16, wherein said feedback control includes:
an optical coupler disposed to couple a portion of an output signal from said PMD compensator that combines said channels;
an optical detector to convert said portion into an electrical signal;
an electrical power detector to detect an AC power of said electrical signal; and
a control circuit to generate said control signals to increase said AC power.
19. A method, comprising:
directing each of a plurality of wavelength-division multiplexed (WDM) optical channels through a common optical path to modify a differential group delay (DGD) in each channel so as to produce an output with modified WDM channels; and
controlling said DGD to reduce an overall signal fading in said output caused by polarization-mode dispersion (PMD) on all of said channels without separately compensating PMD in each channel.
20. The method as in claim 19, further comprising:
measuring power of an AC portion of said output; and
modifying the DGD to increase said power.