초록 ▼

A radar altimeter is described which includes a transmitter for transmitting a radar signal, a receiver for receiving the reflected radar signal, and at least one antenna coupled to one or both of the transmitter and receiver. The altimeter also includes a forward facing millimeter wave (MMW) antenn

A radar altimeter is described which includes a transmitter for transmitting a radar signal, a receiver for receiving the reflected radar signal, and at least one antenna coupled to one or both of the transmitter and receiver. The altimeter also includes a forward facing millimeter wave (MMW) antenna configured to move in a scanning motion and a frequency up/down converter coupled to the MMW antenna, the transmitter, and the receiver, and a radar signal processor. The converter up converts a frequency received from the transmitter to a MMW frequency for transmission through the MMW antenna, and down converts frequencies received to a radar frequency which are output to the receiver. The radar signal processor controls scanning motion of the MMW antenna, processes signals received at the antenna for a portion of the scanning motion, and processes signals received at the MMW antenna for other portions of the scanning motion.

대표청구항 ▼

1. A radar altimeter comprising: a transmitter for transmitting a radar signal toward the ground; a receiver for receiving a reflected radar signal from the ground; at least one altimeter antenna coupled to at least one of said transmitter and said receiver; a forward facing millimeter wa

1. A radar altimeter comprising: a transmitter for transmitting a radar signal toward the ground; a receiver for receiving a reflected radar signal from the ground; at least one altimeter antenna coupled to at least one of said transmitter and said receiver; a forward facing millimeter wave (MMW) antenna configured to provide transmissions that move in a scanning motion; a frequency up/down converter coupled to said MMW antenna, to said transmitter, and to said receiver, said converter up converting a frequency received from said transmitter to a MMW frequency and outputting the MMW frequency to said MMW antenna, said converter down converting a frequency received at said MMW antenna to a radar frequency and outputting the radar frequency to said receiver; and a radar signal processor coupled to said transmitter, to said receiver, and to said MMW antenna, said processor controlling the scanning motion of transmissions from said MMW antenna, processing signals received at said altimeter antenna for a portion of the scanning motion for an altimeter function, and processing signals received at said MMW antenna for other portions of the scanning motion, to provide a forward obstacle warning function. 2. A radar altimeter according to claim 1 wherein the scanning motion of transmissions from said MMW antenna is a raster scanning motion, the raster scanning motion comprising turnaround portions.3. A radar altimeter according to claim 2 wherein signals received at said altimeter antenna are processed during turnaround portions of the raster scanning motion of transmissions from said MMW antenna.4. A radar altimeter according to claim 2 wherein during turnaround portions of the raster scanning motion of transmissions from said MMW antenna, signals are transmitted from said altimeter antenna.5. A radar altimeter according to claim 1 wherein the scanning motion of said MMW antenna comprises an approximate 20 degree vertical and 50 degree horizontal field of view.6. A radar altimeter according to claim 1 wherein to provide the scanning motion, said MMW antenna comprises a transmitting element, a parabolic reflector to reflect signals from said transmitting element, and a reflecting twist plate, said plate reflecting signals reflected from said parabolic reflector and movable to cause the reflected signals to be reflected in a scanning motion.7. A radar altimeter according to claim 1 wherein said frequency up/down converter converts signals received from said transmitter to about 35 GHz.8. A radar altimeter according to claim 1 comprising a circulator which couples said MMW antenna to said frequency up/down converter.9. A radar altimeter according to claim 1 further comprising: a transmit switch alternately coupling said transmitter to one of said altimeter antenna and said frequency up/down converter; and a receiver switch alternately coupling said receiver to one of said altimeter antenna and said frequency up/down converter. 10. A method of operating a radar altimeter to provide forward obstacle notifications, the altimeter including a forward facing millimeter wave (MMW) antenna, a frequency up/down converter coupled to processing circuits of the radar altimeter and the MMW antenna, and altimeter transmit and receive antennas coupled to the processing circuits, said method comprising: causing transmissions from the MMW antenna to move in a scanning motion, the scanning motion having horizontal portions and turnaround portions at ends of the horizontal portions; transmitting, receiving, and processing signals at the MMW antenna during the horizontal portions of the scanning motion to provide warning of forward obstacles; and transmitting, receiving, and processing signals at the altimeter transmit and receive antennas during the turnaround portions of the scanning motion to provide an altimeter function. 11. A method according to claim 10 wherein moving the MMW antenna in a scanning motion comprises movi ng the MMW antenna in a raster scanning motion, the turnaround portion providing a vertical component to the scanning motion.12. A method according to claim 10 wherein moving the MMW antenna in a scanning motion comprises moving the MMW antenna in a raster scanning motion having a 20 degree vertical and 50 degree horizontal field of view.13. A method according to claim 10 wherein the radar altimeter includes a transmitter and wherein transmitting, receiving, and processing signals at the MMW antenna comprises: receiving a signal from the transmitter at the frequency up/down converter; up converting the received signal to a MMW frequency signal; and outputting the MMW frequency signal to the MMW antenna. 14. A method according to claim 13 wherein the radar altimeter includes a circulator coupling the frequency up/down converter to the MMW antenna, and wherein outputting the MMW frequency signal to the MMW antenna comprises: receiving the MMW frequency signal at the circulator; and passing the MMW frequency signal to the MMW antenna. 15. A method according to claim 10 wherein the radar altimeter includes a receiver and wherein transmitting, receiving, and processing signals at the MMW antenna comprises: receiving a MMW frequency signal at the MMW antenna; forwarding the received MMW frequency signal to the frequency up/down converter; down converting the MMW frequency signal to a radar frequency signal; and outputting the radar frequency signal to the receiver. 16. A method according to claim 15 wherein the radar altimeter includes a circulator coupling the frequency up/down converter to the MMW antenna, and wherein forwarding the received MMW frequency signal to the frequency up/down converter comprises: receiving the MMW frequency signal at the circulator; and passing the MMW frequency signal to the frequency up/down converter. 17. A method according to claim 10 wherein the altimeter further includes a reflecting parabolic reflector and a reflecting twist plate, and wherein transmitting, receiving, and processing signals at the MMW antenna comprises: transmitting a signal from the MMW antenna towards the parabolic reflector; reflecting the signal from the parabolic reflector towards the reflecting twist plate; and moving the reflecting twist plate to cause the signals to be reflected in a scanning pattern. 18. A radar altimeter comprising a forward obstacle warning unit, said unit comprising: a frequency up/down converter; and a millimeter wave (MMW) antenna coupled to said converter, said MMW antenna configured to transmit signals received from said frequency up/down converter, said frequency up/down converter configured to receive signals from a transmitter of said radar altimeter, said MMW antenna further configured to pass signals received to said frequency up/down converter, said frequency up/down converter further configured to output signals to a receiver of said radar altimeter. 19. A radar altimeter according to claim 18 wherein said unit comprises a circulator which couples said frequency up/down converter to said MMW antenna.20. A radar altimeter according to claim 18 wherein said unit comprises: a transmit switch configured to switch an output of an altimeter transmitter between an altimeter transmit antenna and said frequency up/down converter; and a receive switch configured to switch an input to an altimeter receiver between an altimeter receive antenna and said frequency up/down converter. 21. A radar altimeter according to claim 18 wherein said forward obstacle warning unit further comprises a reflecting twist plate, said twist plate moving to reflect signals transmitted from said MMW antenna in a raster scanning pattern.22. A radar altimeter according to claim 21 wherein said forward obstacle warning unit is configured to be inactive during vertical portions of the raster scanning pattern and active during horizontal portions of the raster scanning pattern.23. A method for incorporating a forward obstacle warning feature into a radar altimeter which includes a forward obstacle warning unit including a circulator coupling a forward facing millimeter wave (MMW) antenna to a frequency up/down converter, the forward obstacle warning unit coupled to a transmitter and receiver of the radar altimeter through respective transmit and receive switches, the transmitter and receiver also being coupled to at least one radar antenna through the transmit and receive switches for an altimeter function, said method comprising: controlling a position of transmissions from the MMW antenna utilizing a processor of the radar altimeter; processing radar returns received at the MMW antenna to determine a range to a forward object; and processing radar returns received at the at least one radar antenna to determine an altitude. 24. A method according to claim 23 wherein controlling a position of the MMW antenna comprises programming the processor to cause transmissions from the MMW antenna to move in a raster scanning motion.25. A method according to claim 24 wherein processing radar returns received at the MMW antenna comprises processing returns received at the MMW antenna during horizontal portions of the raster scanning motion.26. A method according to claim 24 wherein processing radar returns received at the radar antenna comprises processing returns received at the radar antenna during turnaround portions of the raster scanning motion of the MMW antenna.