1. A power telescoping vehicle mirror assembly comprising:
a bracket mountable to a vehicle;
a mirror head telescopically mounted to the bracket;
a mirror mounted to the head;
a power telescope motor mechanism for telescopically moving the head with respect to the bracket;
a position controller for controlling the extent to which the mirror head extends with respect to the vehicle;
a switch operable by a driver of the vehicle, the switch providing a signal to the position controller; and
an input means for providing the position controller with a set point,
wherein upon actuation of the switch, the head telescopically moves with respect to the bracket from a retracted position to a partially extended position determined by the set point.
2. A power telescoping vehicle mirror assembly claimed in claim 1 further comprising a position sensor for sensing the telescopic position of the mirror head with respect to the mirror bracket.
3. A power telescoping vehicle mirror assembly as claimed in claim 2 further comprising a compensating controller, the compensating controller controlling the angular position of the mirror with respect to the head in response to the telescopic position of the head as sensed by the position sensor.
4. A power telescoping vehicle mirror assembly as claimed in claim 3 wherein the angle between the normal axis of the mirror and the longitudinal axis of the vehicle increases as the mirror head extends away from the mirror bracket.
5. A power telescoping vehicle mirror assembly as claimed in claim 4 wherein the increase is such that a continually acceptable field of view is presented to the driver without the need for manual adjustment of the angular position of the mirror with respect to the head.
6. A power telescoping vehicle mirror assembly comprising:
a bracket mountable to a vehicle;
a head telescopically mounted to the bracket;
a mirror pivotally mounted to the head;
a mirror adjusting motor mechanism for adjusting the angular position of the mirror with respect to the head;
a power telescope motor mechanism for telescopically moving the head with respect to the bracket between a retracted position and an extended position;
a switch operable by a driver of the vehicle, the switch providing a signal to actuate the power telescope motor mechanism;
a position sensor for sensing the telescopic position of the mirror head with respect to the mirror bracket; and
a compensating controller, the compensating controller controlling the angular position of the mirror with respect to the head in response to the telescopic position of the head as sensed by the position sensor.
7. A power telescoping vehicle mirror assembly as claimed in claim 6 wherein the angle between the normal axis of the mirror and the longitudinal axis of the vehicle increases as the mirror head extends away from the mirror bracket.
8. A power telescoping vehicle mirror assembly as claimed in claim 7 wherein the increase is such that a continually acceptable field of view is presented to the driver without the need for manual adjustment of the angular position of the mirror with respect to the head.
9. A vehicle external mirror assembly comprising:
a bracket mountable to a vehicle;
a mirror head mounted to the bracket;
a main mirror mounted to the head;
a spotter mirror mounted to the head, the spotter mirror having a wider field of view than the main mirror; and
a spotter mirror motor mechanism for adjusting the orientation of the spotter mirror with respect to the head.
10. A vehicle external mirror assembly as claimed in claim 9 further comprising control apparatus wherein, if the vehicle is placed in a reversed gear, the orientation of the spotter mirror is automatically adjusted to assume an orientation that provides a different field of view for reversing.
11. A vehicle external mirror assembly as claimed in either claim 10 further comprising:
a power telescope motor mechanism for telescopically moving the head with respect to the bracket;
a position controller for controlling the extent to which the mirror head extends with respect to the vehicle;
a switch operable by a driver of the vehicle, the switch providing a signal to the position controller; and
an input means for providing the position controller with a set point,
wherein upon actuation of the switch, the head telescopically moves with respect to the bracket from a retracted position to a partially extended position determined by the set point.
12. A vehicle external mirror assembly as claimed in claim 11 further comprising a position sensor for sensing the telescopic position of the mirror head with respect to the mirror bracket.
13. A vehicle external mirror assembly as claimed in claim 12 further comprising a compensating controller, the compensating controller controlling the angular position of the mirror with respect to the head in response to the telescopic position of the head as sensed by the position sensor.
14. A vehicle external mirror assembly as claimed in claim 13 wherein the angle between the normal axis of the mirror and the longitudinal axis of the vehicle increases as the mirror head extends away from the mirror bracket.
15. A vehicle external mirror assembly as claimed in claim 14 wherein the increase is such that a continually acceptable field of view is presented to the driver without the need for manual adjustment of the angular position of the mirror with respect to the head.
16. A vehicle external mirror assembly comprising:
a bracket mountable to a vehicle;
a mirror head mounted to the bracket;
a main mirror mounted to the head;
a spotter mirror mounted to the head, the spotter mirror having a wider field of view than the main mirror;
a spotter mirror motor mechanism for adjusting the orientation of the spotter mirror with respect to the head;
a power telescope motor mechanism for telescopically moving the head with respect to the bracket;
a position controller for controlling the extent to which the mirror head extends with respect to the vehicle;
a switch operable by a driver of the vehicle, the switch providing a signal to the position controller; and
an input means for providing the position controller with a set point,
wherein upon actuation of the switch, the head telescopically moves with respect to the bracket from a retracted position to a partially extended position determined by the set point.
17. A vehicle external mirror assembly as claimed in claim 16 further comprising a position sensor for sensing the telescopic position of the mirror head with respect to the mirror bracket.
18. A vehicle external mirror assembly as claimed in claim 17 further comprising a compensating controller, the compensating controller controlling the angular position of the mirror with respect to the head in response to the telescopic position of the head as sensed by the position sensor.
19. A vehicle external mirror assembly as claimed in claim 18 wherein the angle between the normal axis of the mirror and the longitudinal axis of the vehicle increases as the mirror head extends away from the mirror bracket.
20. A vehicle external mirror assembly as claimed in claim 19 wherein the increase is such that a continually acceptable field of view is presented to the driver without the need for manual adjustment of the angular position of the mirror with respect to the head.
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 of radar coordinate registration, the method comprising:
specifying a virtual transponder at a target location;
providing an ionospheric model, and ray tracing through said model from the transmitter to said virtual transponder and back to a receiver to produce propagation parameters;
delaying a virtual transponder signal according to said propagation parameters, and inserting said delayed signal into said receiver; and
using said received virtual transponder signal to perform coordinate registration for further received signals.
2. A method according to claim 1, wherein said ionospheric model is produced by ionospheric assimilative modelling.
3. A method according to claim 1, wherein said ray tracing is performed by analytic ray tracing.
4. A method according to claim 3, wherein said ray tracing is performed by segmented analytic ray tracing.
5. A method according to claim 1, wherein said virtual transponder signal is the transmitted radar signal.
6. A method according to claim 1, wherein said propagation parameters are group delays.
7. A method according to claim 1, wherein said delayed virtual transponder signal is attenuated before insertion into the receiver.
8. A method according to claim 1, wherein said delayed virtual transponder signal is inserted into an antenna feed of the receiver.
9. A method according to claim 1, wherein said delayed virtual transponder signal is inserted into a beam former of the receiver.
10. An over the horizon radar system comprising:
a receiver;
a signal generator for generating a virtual transponder signal;
an ionospheric model of the prevailing ionosphere;
a ray tracing processor for ray tracing through said model from a transmitter to a target location and back to said receiver, and determining propagation parameters;
a signal processor for delaying and attenuating said virtual transponder signal according to said propagation parameters, and inputting said delayed and attenuated signal into said receiver; and
a processor for performing coordinate registration for further received signals based on the received virtual transponder signal.