1. A radio frequency (RF) transceiver, comprising:
a signal generator configured to output a first signal and a second signal, wherein the first signal comprises a local oscillator signal and a frequency of the second signal is derived from a frequency of the first signal;
a frequency multiplier circuit configured to upconvert the first and second signals output by the generator by frequency multiplication, and to output an upconverted first signal and an upconverted second signal as separate signals;
a receiver circuit configured to process a received signal using the upconverted first signal;
a transmitter circuit configured to provide the upconverted second signal to a transmitter channel; and
a switching device configured to provide the upconverted first signal to the receiver circuit and the upconverted second signal to the transmitter circuit,
wherein the transmitter circuit comprises:
an input hybrid device;
an output hybrid device having a first output coupled to a first transmitter channel and a second output coupled to a second transmitter channel;
a plurality of switches configured to provide the upconverted transmit signal between first and second inputs of the input hybrid device;
a first pair of hybrid devices, each having an input coupled to a respective output of the input hybrid device;
a second pair of hybrid devices, each having an output coupled to a respective input of the output hybrid device; and
at least one amplifier coupled between respective outputs of the first pair of hybrid devices and respective inputs of the second pair of hybrid devices,
wherein the transmitter circuit is configured to provide the upconverted second signal to one of the first and second outputs of the output hybrid device.
2. The RF transceiver of claim 1, wherein a difference between the frequency of the second signal and the frequency of the first signal approximates an intermediate frequency (IF) of the transceiver.
3. The RF transceiver of claim 1, wherein the output of the signal generator comprises a time-multiplexed signal.
4. The RF transceiver of claim 1, wherein the frequency multiplier circuit comprises a plurality of frequency multiplier devices.
5. The RF transceiver of claim 1, wherein the frequency multiplier circuit comprises:
a first frequency multiplier coupled between the output of the signal generator and an input of a first band-pass filter;
a second frequency multiplier coupled between an output of the first band-pass filter and an input of a second band-pass filter; and
an amplifier coupled between an output of the second band-pass filter and the switching device.
6. The RF transceiver of claim 1, wherein the plurality of switches comprises:
a first switching device coupled to the switching device through an amplifier and configured to provide between first and second terminals;
a second switching device coupled to the first input of the input hybrid device and configured to provide between the first terminal and a load; and
a third switching device coupled to the second input of the input hybrid device and configured to provide between the second terminal and a load.
7. The RF transceiver of claim 1, wherein the input hybrid device, the output hybrid device, and the first and second pairs of hybrid devices include ninety-degree hybrid devices.
8. The RF transceiver of claim 7, wherein the ninety-degree hybrid devices are implemented as devices etched into a surface of a printed circuit board.
9. The RF transceiver of claim 1, wherein each hybrid device of the first pair of hybrid devices has an input coupled to a load.
10. The RF transceiver of claim 1, wherein each hybrid device of the second pair of hybrid devices has an output coupled to a load.
11. The RF transceiver of claim 1, wherein the at least one amplifier includes four high-power amplifiers.
12. The RF transceiver of claim 1, wherein the receiver circuit is configured to down-convert a carrier frequency of the received signal.
13. The RF transceiver of claim 12, wherein the receiver circuit comprises:
a plurality of amplifiers, each amplifier associated with a receiver channel;
a plurality of switches configured to switching device between respective outputs of the amplifiers to select an associated receiver channel; and
a mixer circuit configured to combine the received signal from the selected receiver channel with the upconverted first signal to generate a received signal having a down-converted carrier frequency.
14. The RF transceiver of claim 13, wherein the mixer circuit includes a single stage in-phasequadrature phase (IQ) mixer.
15. The RF transceiver of claim 14, wherein the IQ mixer is configured as a front-end of an image rejection mixer implemented in off-gimbal electronics.
16. The RF transceiver of claim 13, wherein the mixer circuit comprises:
an attenuator coupled between the fourth switching device and an input of a low-noise amplifier; and
a band-pass filter coupled between an output of the low-noise amplifier and an input of the IQ mixer,
wherein the IQ mixer combines the received signal processed by the attenuator, the low-noise amplifier, and the band-pass filter with the upconverted receive signal to generate the received signal having the down-converted carrier frequency.
17. The RF transceiver of claim 1, wherein the RF transceiver comprises:
a plurality of switches coupled to a plurality of antenna channels.
18. The RF transceiver of claim 17, wherein the antenna channels includes first and second transmitterreceiver channels and first and second receiver channels.
19. The RF transceiver of claim 18, wherein the plurality of switches comprises:
a seventh switching device coupled to the first transmitterreceiver channel and configured to toggle between the first output of the output hybrid device and a first input of the receiver circuit; an
eighth switching device coupled to the first receiver channel and configured to toggle between a second input of the receiver circuit and a load;
a ninth switching device coupled to the second receiver channel and configured to toggle between a third input of the receiver circuit and a load; and
a tenth switching device coupled to the second transmitterreceiver channel and configured to toggle between the second output of the output hybrid device and a fourth input of the receiver circuit.
20. The RF transceiver of claim 18, wherein the antenna channels include left circularly polarized channels and right circularly polarized channels.
21. The RF transceiver of claim 1 in combination with a radar system, comprising:
an antenna configured to transmit and receive RF signals; and
a processor configured to process the RF signals.
22. The RF transceiver of claim 1, wherein the RF transceiver is implemented as a single layer on a printed circuit board.
23. A radio frequency (RF) transceiver, comprising:
means for generating a first signal and a second signal, wherein the first signal comprises a local oscillator signal and wherein a frequency of the second signal is derived from a frequency of the first signal;
means for upconverting the generated first and second signals by frequency multiplication, and for outputting an upconverted first signal and an upconverted second signal as separate signals;
means for selecting a receiver path or a transmitter path and for providing the upconverted first signal to the receiver path and the upconverted second signal to the transmitter path in accordance with the selected path;
means for processing a received signal using the upconverted first signal when the receiver path is selected; and
means for providing the upconverted second signal to a transmitter channel when the transmitter path is selected,
wherein the means for providing the upconverted second signal comprise:
an input hybrid device;
an output hybrid device having a first output coupled to a first transmitter channel and a second output coupled to a second transmitter channel;
a plurality of switches configured to provide the upconverted transmit signal between first and second inputs of the input hybrid device;
a first pair of hybrid devices, each having an input coupled to a respective output of the input hybrid device;
a second pair of hybrid devices, each having an output coupled to a respective input of the output hybrid device; and
at least one amplifier coupled between respective outputs of the first pair of hybrid devices and respective inputs of the second pair of hybrid devices,
wherein the transmitter circuit is configured to provide the upconverted second signal to one of the first and second outputs of the output hybrid device.
24. A method for transmitting and receiving radio frequency (RF) signals, comprising:
generating a first signal and a second signal, wherein the first signal comprises a local oscillator signal and wherein a frequency of the second signal is derived from a frequency of the first signal;
upconverting the generated first and second signals by frequency multiplication, and outputting an upconverted first signal and an upconverted second signal as separate signals;
selecting a receiver path or a transmitter path, and providing the upconverted first signal to the receiver path or the upconverted second signal to the transmitter path in accordance with the selected path;
processing a received signal using the upconverted first signal; and
providing the upconverted second signal to a transmitter channel,
wherein the providing of the upconverted second signal to a transmitter channel comprises:
providing the upconverted second signal to a transmitter circuit comprising:
an input hybrid device;
an output hybrid device having a first output coupled to a first transmitter channel and a second output coupled to a second transmitter channel;
a plurality of switches configured to provide the upconverted transmit signal between first and second inputs of the input hybrid device;
a first pair of hybrid devices, each having an input coupled to a respective output of the input hybrid device;
a second pair of hybrid devices, each having an output coupled to a respective input of the output hybrid device; and
at least one amplifier coupled between respective outputs of the first pair of hybrid devices and respective inputs of the second pair of hybrid devices,
wherein the transmitter circuit is configured to provide the upconverted second signal to one of the first and second outputs of the output hybrid device.
25. The method of claim 24, wherein a difference between the frequency of the second signal and the frequency of the first signal approximates an intermediate frequency (IF) of the transceiver.
26. The method of claim 24, wherein generating the first signal and the second signal comprises:
generating a time-multiplexed signal based on the first signal and second signal.
27. The method of claim 24, wherein processing a received signal comprises:
selecting a receiver channel; and
combining the received signal from the receiver channel with the upconverted first signal.
28. The method of claim 27, wherein the combining comprises:
down-converting a carrier frequency of the received signal using a single stage in-phasequadrature phase (IQ) mixer.
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 for determining the bearing surface in images of skin prints, the skin having ridges and furrows and the images existing in the form of image data, characterized in that the image is filtered with a plurality of Gabor filters with different directions of the cosine function in the spatial domain, in that areas are determined from the filter responses which areas are each distinguished by an approximate direction, preset by the particular Gabor filter, of the ridgesfurrows, and in that the areas are combined to an overall area that represents the bearing surface.
2. A method as claimed in claim 1, characterized in that four Gabor filters are used.
3. A method as claimed in claim 2, characterized in that the directions of the Gabor filters are determined by angles of 22.5\xb0, 67.5\xb0, 112.5\xb0 and 157.5\xb0 to an edge of the image.
4. A method as claimed in claim 1, characterized in that, to allow the surfaces to be determined from the filter responses tile by tile into which the image is divided, a respective variance is derived from the given filter response, and in that tiles having a variance that is greater than a preset threshold value are assigned to the respective surface.
5. A method as claimed in claim 4, characterized in that the derivation of the variance is performed by deriving the variances for tiles that overlap one another.
6. A method as claimed in claim 5, characterized in that, at a resolution of approximately 500 dpi, the size of the tiles used for deriving the variance is 16\xd716 pixels, which tiles are each processed in steps of eight pixels.
7. A method as claimed in claim 1, characterized in that the pixels are adapted by smoothing filters to the respective predominant environment of the respective pixel.
8. A method as claimed in claim 1, characterized in that the surface area of the areas determined up till then is determined and in that surfaces whose surface area is smaller than a preset size are suppressed.
9. A method as claimed in claim 8, characterized in that the surface area is determined by outlining the bearing surfaces by means of an edge-tracing algorithm.
10. A method as claimed in claim 1, characterized in that, on both sides of the area of interest determined up to that point, pointers that start from either end of the side is set each to the outermost of the tiles determined as belonging to the bearing surface, the pointers then moving towards one another and, from line to line, assuming the position of a tile that is situated farther outwards or, if there is an indentation, remaining in the same position, and the travel of the pointers until they meet forms the respective edge of the definitive bearing surface.