Patent Description:
Radar devices have been used for many years to help forecast weather and for directing aeroplanes to less turbulent and cloudy areas of the sky. However, the known systems are complex and elaborate, and therefore expensive to manufacture.

Some background information may be found in <CIT>, <CIT>, and <CIT>.

The present invention offers a device which is able to overcome these problems. In a first aspect, the invention provides a radar device for providing data related to atmospheric conditions comprising a transceiver with a single input/output port, the transceiver arranged to generate a frequency modulated continuous radar wave signal and direct it via the single input/output port to a first switch, the first switch arranged to direct the signal to a transmission branch including a first antenna for transmission thereof, the radar device further comprising a receiving branch, separate from the transmission branch, arranged to direct received reflected radar waves and direct them as signals to the single input/output port of the transceiver via the first switch, wherein the first switch is arranged to isolate the transmission branch from the receiving branch.

The first switch may be arranged to alternately connect only the transceiver with the transmission branch, and the transceiver with the receiving branch. The first switch may be a circulator. The radar device may further comprise a transmitter amplifier in the transmission branch. The transmitter amplifier may be arranged to provide a gain of approximately 30dB, although other magnitudes are contemplated. The radar device may further comprise a receiver amplifier in the receiving branch. The receiver amplifier may be a low noise amplifier. The receiver amplifier may be arranged to provide a gain of approximately 50dB, although other magnitudes are contemplated.

The separation of the transmission and receiving branches may enable amplification to be added to the generated signal and separately to the received signal, in order to increase the overall sensitivity of the system.

The first antenna may be arranged to also receive the reflected radar waves. In this regard, the radar device may further comprise a second switch arranged to direct the transmission signals to the first antenna.

In other words, a single antenna may be used to transmit and receive signals.

The second switch may be arranged to direct the received signals from the reflected radar waves to the receiving branch, and the second switch may be arranged to isolate the transmission branch from the receiving branch.

The second switch may be arranged to alternately connect only the first antenna with the transmission branch, and the first antenna with the receiving branch.

The radar device may further comprise a separate second antenna in the receiving branch to receive the reflected radar waves.

The radar device may further comprise a digital analyser for processing the received signals. This may include a display, data storage and a communications device.

The radar device may further comprise an upconverter for increasing the frequency of the generated radar wave signal in the transmission branch. The upconverter may be arranged to increase the frequency in the range <NUM> to <NUM> although other frequencies are contemplated.

The radar device may further comprise an upconverter for increasing the frequency of the received signal. The upconverter may be arranged to increase the frequency by approximately <NUM>.

Either or both upconverters may be useful to shift the received signals away from unwanted "noise" created close to the transmitting frequency which is associated with short distances in the signal evaluation. This may increase the sensitivity of the device.

The transceiver may be configured to generate the radar wave signal in a reverse saw-tooth arrangement, such that the frequency of the radar wave signal decreases gradually over time after an initial, relatively instantaneous, increase.

The transceiver may be configured to generate the radar wave signal at a frequency of approximately <NUM>. For instance, it may be in the range <NUM> to <NUM>, although other frequencies are contemplated.

The first switch and transceiver may be integrated into a single unit.

In a second aspect, the invention provides a method of operating a radar device according to the first aspect, for providing data related to atmospheric conditions, comprising the steps of generating a frequency modulated continuous radar wave signal, directing the signal via the single input/output port to the first switch, and directing the signal to the first antenna via a transmission branch, the method further comprising the steps of receiving reflected radar waves and directing them via a receiving branch and the first switch to the transceiver via the single input/output port.

The method may further comprise the step of processing the received signals. The method may further comprise the step of increasing the frequency of the generated radar wave signal before it reaches the first antenna. The method may further comprise the step of increasing the frequency of the received signal before it reaches the transceiver. The method may further comprise the step of generating the radar wave signal in a reverse saw-tooth arrangement, such that the frequency of the radar wave signal decreases gradually over time after an initial, relatively instantaneous, increase.

The frequency of <NUM>-<NUM>, which is an International Telecommunications Union (ITU) approved waveband for meteorological observations, allows the penetration and resolution of clouds to be greatly increased.

Most conventional radar devices, including "cloud profilers", use pulsed radar, wherein the receiving module is closed for a short time to protect the receiver from the full strength of the transmitted signal.

The reversed saw-tooth profile of the FMCW waveform acts together with the upconversion to increase greatly the sensitivity at which reflected signals can be discriminated from system noise. The waveform may be described as a scanning waveform.

<FIG> and <FIG> are schematic diagrams of radar devices;.

<FIG> are graphs of transmitted and received radar signals.

It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other sequences than described or illustrated herein.

Similarly, it is to be noticed that the term "connected", used in the description, should not be interpreted as being restricted to direct connections only. Thus, the scope of the expression "a device A connected to a device B" should not be limited to devices or systems wherein an output of device A is directly connected to an input of device B. It means that there exists a path between an output of A and an input of B which may be a path including other devices or means. "Connected" may mean that two or more elements are either in direct physical or electrical contact, or that two or more elements are not in direct contact with each other but yet still co-operate or interact with each other. For instance, wireless connectivity is contemplated.

Reference throughout this specification to "an embodiment" or "an aspect" means that a particular feature, structure or characteristic described in connection with the embodiment or aspect is included in at least one embodiment or aspect of the present invention. Thus, appearances of the phrases "in one embodiment", "in an embodiment", or "in an aspect" in various places throughout this specification are not necessarily all referring to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, the particular features, structures or characteristics of any embodiment or aspect of the invention may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments or aspects.

Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art.

In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

The use of the term "at least one" may mean only one in certain circumstances. The use of the term "any" may mean "all" and/or "each" in certain circumstances.

The principles of the invention will now be described by a detailed description of at least one drawing relating to exemplary features. It is clear that other arrangements can be configured according to the knowledge of persons skilled in the art without departing from the underlying concept or technical teaching, the invention being limited only by the terms of the appended claims.

In <FIG>, transceiver <NUM> generates a signal which is sent to the switch <NUM>. The switch <NUM> allows an input from the transceiver to be only directed to the transmission side of the device <NUM>, <NUM>, <NUM>, and not to the receiving side of the device <NUM>, <NUM>, <NUM>. The switch may be a circulator. A transmission upconverter <NUM> allows for the frequency of the signal to be increased by approximately <NUM> to <NUM>, although other frequency magnitudes are contemplated. It then is passed to a transmission amplifier <NUM> for onward broadcast via a transmission antenna <NUM>. Either of the transmission upconverter <NUM> and the transmission amplifier <NUM> are optionally present.

After the radar waves have been scattered and reflected by a target or targets, for example, within the atmosphere some will be collected by the receiving antenna <NUM>. This received signal will be amplified by a receiving amplifier <NUM> before being directed to a receiving upconverter <NUM> and onward to the switch <NUM>. Either of the receiving upconverter <NUM> and the receiving amplifier <NUM> are optionally present. The switch <NUM> is arranged to only allow inputs received from the receiving side to be directed to the transceiver <NUM> and not to the transmission side of the device.

It is to be understood that instead of a transmission antenna <NUM> and a separate receiving antenna <NUM>, a single transmission/receiving antenna may be provided. This is shown in <FIG> where the transmission <NUM> and receiving <NUM> antennae are replaced with a single antenna <NUM>. The single antenna <NUM> is connected to both the transmission side (or branch) and the receiving side (or branch) of the device via a switch <NUM>. The switch <NUM> may be a circulator. The switch <NUM> is arranged to only allow inputs received from the antenna <NUM> to be directed to the receiving side and not to the transmission side of the device. Likewise, it is arranged to only allow signals generated by the transceiver to reach the single antenna <NUM> via the transmission side and not via the receiving side.

For either case (single or twin antennae) the received signal may have its frequency shifted by the upconverter <NUM> by approximately <NUM>, although other magnitudes are contemplated. The signal is also processed either in the transceiver <NUM> and/or in a digital processor/display <NUM>.

One of the aims of the device is to obtain reflected radar waves from relatively close atmospheric phenomena. Traditional pulse radar systems have trouble receiving this data because the receiving side of the device is closed to prevent it picking-up the transmitted signal. The present device may overcome this, supported by, but not necessarily exclusively relying on, the use of the circulator and separate antennae. Moreover, the receiving upconverter <NUM> may shift the frequency of the received signal away from the frequency of the transmitted signal. Alternatively, and/or additionally, the transmitted signal may be increased in frequency, away from the signal output by the transceiver, by means of the transmission upconverter <NUM>. Finally, it is also possible to generate the transmission signal in a reverse wave form as shown in <FIG>.

In <FIG>, the standard saw-tooth wave forms <NUM> are shown on a graph with frequency on the y-axis <NUM> and time on the x-axis <NUM>. The transmitted wave form <NUM> comprises a sloping section <NUM> where the signal increases in frequency gradually from a base line over time followed by a substantially instantaneous reduction <NUM> back to the base line. This is repeated forming a "saw tooth" profile.

The received wave form 101A is also shown. It has the same saw tooth profile. Since the received signal has been received after the transmitted signal the wave form is shown shifted to the right slightly. Such received signals may have interference due to unwanted "noise" created close to the transmitting frequency which are associated with short distances in the signal evaluation. To mitigate this, it is possible to upconvert the receive signal with the upconverter to move the received signal 101A away from the x-axis. However, there is a limit to how far the received signal can be upconverted as otherwise it can cause problems in that the two signals (transmitted <NUM> and received 101A) are relatively close to one another such that it is difficult to distinguish the received signal from the transmitted signal. In this regard, the sloping section 130A of the received signal will be closer to the sloping section <NUM> of the transmitted signal.

An alternative solution is to transmit the signal in a reverse saw-tooth wave form <NUM> as shown on a graph in <FIG> where frequency is on the y-axis <NUM> and time is on the x-axis <NUM>. The wave form <NUM> comprises a signal substantially instantaneously increasing in frequency <NUM> from a base line followed by a sloping section <NUM> gradually decreasing in frequency back to the base line. This is repeated producing the "reverse saw tooth" profile.

Claim 1:
A radar device for providing data related to atmospheric conditions comprising a transceiver (<NUM>) with a single input/output port, the transceiver (<NUM>) arranged to generate a frequency modulated continuous radar wave signal and direct it via the single input/output port to a first switch (<NUM>), the first switch (<NUM>) arranged to direct the signal to a transmission branch including a first antenna (<NUM>) for transmission thereof, the radar device further comprising a receiving branch, separate from the transmission branch, arranged to direct received reflected radar waves and direct them as signals to the single input/output port of the transceiver (<NUM>) via the first switch (<NUM>), wherein the first switch (<NUM>) is arranged to isolate the transmission branch from the receiving branch.