1. A method of removing solar interference from radar data acquired from a radar site location, comprising:
extracting a site latitude, a site longitude and scan elevation time from the radar data;
determining the position of the Sun for the site latitude, the site longitude and the scan time;
determining if a radial has been contaminated with solar interference; and
removing the solar interference.
2. The method of claim 1, wherein said method is performed if the Sun’s position is with approximately a threshold elevation angle of an elevation scan angle.
3. The method of claim 2, wherein the threshold elevation angle is between 0.5 and 1.3 degrees.
4. The method of claim 1, further comprising accounting for inaccuracies in a clock at a radar site from which the radar data was received.
5. The method of claim 1, further comprising:
identifying the radial closest to a Sun azimuth and said radial’s neighboring radials; and
sorting a predetermined number of radials closest to the Sun position based on a number of non-zero echoes in each radial.
6. The method of claim 1, wherein determining if a radial has been contaminated with solar interference further comprises:
determining if the number of non-zero echoes in a highest priority radial exceeds a predetermined threshold number of non-zero echoes;
determining if a difference of the number of non-zero echoes between the highest and lowest radial exceed a percentage threshold; and
determining if a three highest priority radials are azimuthally consecutive, and if so, returning a middle radial, otherwise returning a radial with the highest number of non-zero echoes.
7. The method of claim 1, wherein removing the solar interference further comprises:
for each range gate of a radial N identified as being contaminated by solar interference, determining if an echo in a current range gate exceeds an intensity threshold; and
for echoes in the current range gate that do not exceed the intensity threshold, examining the current range gates for radials N\u22122 and N+2 determine if an echo for the current range gate for those radials is zero.
8. The method of claim 7, wherein the intensity threshold is variable over a length and increases as the range increases for a radial.
9. The method of claim 7, wherein if the range gates for the radials N\u22122 and N+2 are not zero, then the value of the current range gate for radial N is not changed and the next range gate for the radial N is examined.
10. The method of claim 7, wherein if the range gates for the radials N\u22122 and N+2 are zero, then the value of the current range gate for radial N is changed to zero and the next range gate for the radial N is examined.
11. The method of claim 7, further comprising:
for each range gate of the N+1 and N\u22121 radials, determining if an echo in a current range gate in the N+1 or N\u22121 radial does not exceed the intensity threshold; and
if an echo in the current range gate in the N+1 or N\u22121 radial does not exceed the intensity threshold, examining if the current range gates for both radials N\u22121 and N+1 are zero; and
setting a value of the current range gate for the radial N to 0 if the current range gates for both radials N\u22121 and N+1 are zero.
12. A method of determining if radar data acquired from a radar site location contains solar interference, comprising:
extracting a site latitude, a site longitude and scan elevation time from the radar data;
determining the position of the Sun for the site latitude, site longitude and the scan time;
determining if an elevation angle of the Sun is within approximately a threshold elevation angle of an elevation scan angle; and
examining radar data for radials closest to the Sun’s position if the Sun is approximately said threshold elevation angle.
13. The method of claim 12, wherein the threshold elevation angle is between 0.5 and 1.3 degrees.
14. The method of claim 12, wherein examining radar data for radials closest to the Sun’s position further comprises:
determining if the number of non-zero echoes in a highest priority radial exceeds a predetermined threshold number of non-zero echoes;
determining if a difference of the number of non-zero echoes between the highest and lowest radial exceed a percentage threshold; and
determining if a three highest priority radials are azimuthally consecutive, and if so, returning a middle radial, otherwise returning a radial with the highest number of non-zero echoes.
15. The method of claim 12, further comprising removing the solar interference from radials containing said solar interference.
16. The method of claim 15, wherein removing the solar interference further comprises:
for each range gate of a radial N identified as being contaminated by solar interference, determining if an echo in a current range gate exceeds an intensity threshold; and
for echoes in the current range gate that do not exceed the intensity threshold, examining the current range gates for radials N\u22122 and N+2 determine if an echo for the current range gate for those radials is zero.
17. The method of claim 16, wherein the intensity threshold is variable over a length and increases as the range increases for a radial.
18. The method of claim 16, wherein if the range gates for the radials N\u22122 and N+2 are not zero, then the value of the current range gate for radial N is not changed and the next range gate for the radial N is examined.
19. The method of claim 16, wherein if the range gates for the radials N\u22122 and N+2 are zero, then the value of the current range gate for radial N is changed to zero and the next range gate for the radial N is examined.
20. The method of claim 16, further comprising:
for each range gate of the N+1 and N\u22121 radials, determining if an echo in a current range gate in the N+1 or N\u22121 radial does not exceed the intensity threshold; and
if an echo in the current range gate in the N+1 or N\u22121 radial does not exceed the intensity threshold, examining if the current range gates for both radials N\u22121 and N+1 are zero; and
setting a value of the current range gate for the radial N to 0 if the current range gates for both radials N\u22121 and N+1 are zero.
21. A method of determining and removing solar interference from radar data acquired from a radar site location, comprising:
extracting a site latitude, a site longitude and scan elevation time from the radar data;
determining the position of the Sun for the site latitude, the site longitude and the scan time;
determining if an elevation angle of the Sun is within approximately a threshold elevation angle of an elevation scan angle, and if so:
compensating for inaccuracies in a clock time associated with said radar data;
determining if a radial has been contaminated with solar interference if the Sun’s position is approximately a threshold angle; and
removing the solar interference.
22. The method of claim 21, wherein the threshold elevation angle is between 0.5 and 1.3 degrees.
23. The method of claim 21, wherein determining if a radial has been contaminated with solar interference further comprises:
determining if the number of non-zero echoes in a highest priority radial exceeds a predetermined threshold number of non-zero echoes;
determining if a difference of the number of non-zero echoes between the highest and lowest radial exceed a percentage threshold; and
determining if a three highest priority radials are azimuthally consecutive, and if so, returning a middle radial, otherwise returning a radial with the highest number of non-zero echoes.
24. The method of claim 21, wherein removing the solar interference further comprises:
for each range gate of a radial N identified as being contaminated by solar interference, determining if an echo in a current range gate exceeds an intensity threshold;
for echoes in the current range gate that do not exceed the intensity threshold, examining the current range gates for radials N\u22122 and N+2 determine if an echo for the current range gate for those radials is zero; and
if the range gates for the radials N\u22122 and N+2 are not zero, then the value of the current range gate for radial N is not changed, and if the range gates for the radials N\u22122 and N+2 are zero, then the value of the current range gate for radial N is changed to zero; and
examining the next range gate for the radial N is examined.
25. The method of claim 24, further comprising:
for each range gate of the N+1 and N\u22121 radials, determining if an echo in a current range gate in the N+1 or N\u22121 radial does not exceed the intensity threshold; and
if an echo in the current range gate in the N+1 or N\u22121 radial does not exceed the intensity threshold, examining if the current range gates for both radials N\u22121 and N+1 are zero; and
setting a value of the current range gate for the radial N to 0 if the current range gates for both radials N\u22121 and N+1 are zero.
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 method of position demodulation in an optical wireless link (OWL), the method comprising the steps of:
polarizing a light beam transmitted from a first OWL; and
passing the polarized light beam transmitted from the first OWL through a polarization detector within a second OWL to detect amplitude changes as the beam passes through at least one polarity-detecting filter.
2. The method according to claim 1 further comprising the step of demodulating position data in response to the amplitude changes.
3. The method according to claim 1 wherein the step of polarizing a light beam transmitted from a first OWL comprises polarizing a light beam into a desired set of regions such that each region has a polarity that is distinct from the polarity associated with each other region.
4. The method according to claim 1 wherein the step of passing the polarized light beam transmitted from the first OWL through a polarization detector within a second OWL to detect amplitude changes as the beam passes through at least one polarity-detecting filter comprises passing the polarized light beam transmitted from the first OWL through a plurality of polarity detecting filters such that each region within the desired set of regions has a distinct polarity detecting filter associated therewith.
5. The method according to claim 1 wherein the step of polarizing a light beam transmitted from a first OWL comprises changing the polarization of the transmitted beam in a defined sequence.
6. The method according to claim 1 wherein the step of polarizing a light beam transmitted from a first OWL comprises modulating the polarization of the transmitted beam to achieve a desired temporal property.
7. The method according to claim 1 wherein the step of passing the polarized light beam transmitted from the first OWL through a polarization detector within a second OWL to detect amplitude changes as the beam passes through at least one polarity-detecting filter comprises passing the polarized light beam transmitted from the first OWL through a polarization detector to detect polarization of the transmitted beam in a defined sequence.
8. The method according to claim 1 wherein the step of passing the polarized light beam transmitted from the first OWL through a polarization detector within a second OWL to detect amplitude changes as the beam passes through at least one polarity-detecting filter comprises passing the polarized light beam transmitted from the first OWL through a polarization detector such that polarization of the transmitted beam is demodulated according to a desired temporal property.
9. The method according to claim 1 wherein the step of passing the polarized light beam transmitted from the first OWL through a polarization detector within a second OWL to detect amplitude changes as the beam passes through at least one polarity-detecting filter comprises passing the polarized light beam transmitted from the first OWL through a single variable polarity detecting filter that operates in response to an input voltage level to change its angle of polarity such that data corresponding to each region within the desired set of regions is demodulated in response to amplitude changes.
10. A method of position demodulation in an optical wireless link (OWL), the method comprising the steps of:
polarizing a light beam transmitted from a first OWL into a desired set of regions such that each region has a polarity angle that is distinct from the polarity angle associated with each other region; and
passing the polarized light beam transmitted from the first OWL through a polarization detector within a second OWL to detect amplitude changes associated with each region.
11. The method according to claim 10 further comprising the step of demodulating position data corresponding to each region in response to the amplitude changes.
12. The method according to claim 10 wherein the step of polarizing a light beam transmitted from a first OWL into a desired set of regions comprises polarizing the light beam transmitted from a first OWL into at least one quadrant such that opposite corners of the at least one quadrant are orthogonal to one another.
13. The method according to claim 10 wherein the step of polarizing a light beam transmitted from a first OWL into a desired set of regions comprises passing the light beam through the center of a polarizing filter to polarize each region of the light beam in a different direction.
14. The method according to claim 13 wherein the step of polarizing a light beam transmitted from a first OWL into a desired set of regions further comprises passing the light beam through the center of a polarizing filter to polarize each quadrant of the light beam in a different direction.
15. The method according to claim 14 wherein the step of polarizing a light beam transmitted from a first OWL into a desired set of regions further comprises polarizing each quadrant of the light beam such that opposite corners will be orthogonal to one another.
16. A position demodulation system for an optical wireless link (OWL) comprising:
a laser generator;
a MEM mirror operational to reflect a light beam emitted by the laser generator; and
a polarizing filter positioned between the laser generator and the MEM mirror such that the light beam emitted by the laser generator is polarized into a desired set of regions prior to reflection of the light beam by the MEM mirror.
17. The position demodulation system according to claim 16 further comprising:
an optical receiver; and
a polarization detector, wherein the optical receiver is operational to detect amplitude changes associated with a polarized light beam transmitted from a remote OWL subsequent to the polarized light beam passing through the polarization detector.
18. The position demodulation system according to claim 17 wherein the optical receiver and polarization detector are further operational to achieve position demodulation in response to the amplitude changes.
19. The position demodulation system according to claim 16 wherein the polarizing filter is further operational to polarize each quadrant of the light beam emitted by the laser generator in a different direction.
20. A position demodulation system for an optical wireless link (OWL) comprising:
an optical receiver; and
a polarization detector, wherein the optical receiver is operational to detect amplitude changes associated with a polarized light beam transmitted from a remote OWL subsequent to the polarized light beam passing through the polarization detector.
21. The position demodulation system according to claim 20 wherein the optical receiver and polarization detector are further operational to achieve position demodulation in response to the amplitude changes.
22. The position demodulation system according to claim 20 further comprising:
a laser generator;
a MEM mirror operational to reflect a light beam emitted by the laser generator; and
a polarizing filter positioned between the laser generator and the MEM mirror such that the light beam emitted by the laser generator is polarized into a desired set of regions prior to reflection of the light beam by the MEM mirror.
23. The position demodulation system according to claim 22 wherein the polarizing filter is configured to polarize each quadrant of the light beam emitted by the laser generator in a different direction.
24. The position demodulation system according to claim 23 wherein the polarizing filter is farther configured to polarize each quadrant of the light beam emitted by the laser generator such that opposite corners will be orthogonal to one another.