Radar sensor and method of operating a radar sensor

Abstract

A radar sensor has an analog front-end with an in-phase, I, channel output and a quadrature-phase, Q, channel output. The radar sensor operates in a pulsed operation. A mode switch is used to couple a selected one of the I and Q-channel outputs to an analog processing circuit. The mode switch is operable in a first, I-channel, mode, a second, Q- channel, mode, and a third, time division multiplexing dual-channel, mode. In this way, the radar can operate in power efficient single-channel mode or a dual-channel mode for greater robustness to interference.

Description

[0001] 2024PF80303

[0002] 1

[0003] Radar sensor and method of operating a radar sensor

[0004] FIELD OF THE INVENTION

[0005] The present invention generally relates to a radar sensor for motion detection.

[0006] BACKGROUND OF THE INVENTION

[0007] Motion detectors are used in many applications ranging from burglar alarms to automatic door openers or automatic control of illumination or HVAC systems. For example, motion detectors are often used in offices, e.g. in conference rooms, to detect when people are present to steer light modules and / or HVAC systems such that lights, ventilation, heating and air conditioning are turned on when people are present and automatically turned off when no people are present. Automatic control of these systems based on motion detection has the potential to save large amounts of energy by avoiding that lights or air conditioning units in an office remain on during the night, or over the weekend, when no people are present.

[0008] Typically, Passive Infrared Sensors, PIRs, are used to detect motion. PIRs operate by registering incident IR radiation and when e.g., people move in front of the PIR the intensity distribution on the PIR sensor changes which can be taken as an indication that people are present in front of the sensor. A drawback with PIRs is, however, that they are not very sensitive to small motions, e.g. small hand gestures or small head motions, made by people sitting around a conference table may not always be detected by the PIR whereby the lights, or other systems, are deactivated while people are still using the conference room. In other words, the PIRs are prone to high false negative rates meaning that PIRs often fail to sense motion when there in fact is motion to detect.

[0009] In view of the drawbacks of PIRs, radar sensors have been used instead. Radar sensors are active sensors which transmit a radar signal into the environment and measure the reflected radar signal. If an object (e.g., a human) moves this will alter the reflected radar signal and this alteration can be used as an indication of motion. Radar sensors tend to be much more sensitive compared to PIRs such that even small motions can be detected which reduced the false negative rate. At the same time, radar signals can penetrate non-metal materials such as glass, plastic or drywall meaning that it is possible to hide radar motion 2024PF80303

[0010] 2 sensors in walls or integrate the radar motion sensor into devices without the radar sensor being visible.

[0011] For example, more and more lighting luminaires incorporate integrated radar sensors for lighting control. For this integration, there is a desire to minimize the sensor size and reduce the sensor cost. The power consumption of the radar sensor is also important if there is a very limited power budget. It is for example known to operate a radar sensor using a pulsed operation for power reduction.

[0012] Some radar motion sensors (e.g., 24 GHz Doppler radar sensors) are capable of providing both in-phase (I) and quadrature-phase (Q) baseband signals and support more advanced sensing features beyond simple motion detection. Also, via digital signal processing based on both I and Q signals, potential environmental interference (such as rain in the case of outdoor applications) can be removed. This can improve the overall motion detection performance with fewer false triggers.

[0013] To implement a pulsed operation of a radar sensor with both I and Q-channels, there are a number of existing options.

[0014] A first option is to use two sets of duplicated analog processing circuits. These circuits can be used to collect the I-channel signal and the Q-channel signal almost simultaneously and independently. The main problem of this option is a duplication of sensor hardware, hence increasing the sensor size and cost. For some luminaires, there is a limitation on the space to integrate the sensor and it is not possible to perform the I and Q dual-channel signal processing at the same time. In such cases, it is only possible to keep one set of analog baseband processing circuits for either the I-channel signal or the Q-channel signal.

[0015] A second option is to use time division multiplexing (TDM) for the operation of one set of analog processing circuits. A time division multiplexing (TDM) operation is widely used. It allows the I-channel signal and the Q-channel signal to be collected sequentially by switching the single set of analog processing circuits. The main problem of this option is that the operation time needs to be long enough to enable signal stabilization and ADC settling to prevent signal distortion, e.g., after switching from the I-channel to the Q-channel in order to prevent distortion on the Q-channel signal. This will result in a higher duty cycle (if the same duty frequency is used) and result in higher power consumption than the first option above.

[0016] KR20230099592 A discloses an impulse transceiver comprises: a transmitter transmitting an impulse transmission signal; a receiver receiving the impulse reception signal reflected and returned from a detection object; and an I / Q generator receiving an LO signal 2024PF80303

[0017] 3 generated by a voltage-controlled oscillator of the transmitter and generating an I-LO signal and a Q-LO signal whose phases are orthogonal to each other. The receiver comprises: a frequency down converter mixing the I-LO signal, the Q-LO signal, and the impulse reception signal and outputting an I detection signal and a Q detection signal down-converted to a baseband frequency; an IQ switch unit selecting and outputting one of the I detection signal and the Q detection signal; and one analog-to-digital converter converting and outputting one of the I detection signal and the Q detection signal output from the IQ switch unit into a digital signal.

[0018] EP0940690 A2 relates to a microwave sensor for determining the velocity and direction of a moving object comprises a mixer, phase shifter, and receive / transmit antenna mounted in series, the mixer having a single intermediate frequency (IF) output. The intermediate frequency output is switched synchronously with the phase shifter which is switched between 0 DEG phase shift and 45 DEG phase shift. Although the mixer has only a single intermediate frequency output (IF), the switching provides two output channel signals (I) and (Q) with a phase difference of 90 DEG therebetween to enable determination of the direction of movement.

[0019] There remains a need for a radar system with pulsed operation of a dualchannel radar sensor, using only one set of analog baseband processing circuits, but without the power consumption issues of a conventional TDM radar.

[0020] SUMMARY OF THE INVENTION

[0021] The invention is defined by the claims.

[0022] According to examples in accordance with an aspect of the invention, there is provided a radar sensor, comprising: a radar analog front-end comprising a transmitter and receiver, the analog front-end comprising an in-phase, I, channel output and a quadrature-phase, Q, channel output; an analog processing circuit for processing either the I-channel or Q-channel output; a switch arrangement for enabling a pulsed operation of the analog front-end; and a mode switch between the analog front-end and the analog processing circuit, wherein the mode switch is for coupling a selected one of the I-channel and Q- channel outputs to the analog processing circuit, wherein the mode switch is operable in: 2024PF80303

[0023] 4 a first, I-channel, mode; a second, Q-channel, mode; and a third, dual-channel time division multiplexing, mode.

[0024] This radar sensor uses a pulsed operation of the analog front-end to reduce power consumption. It also only needs to process one channel of radar data at a time, because either a single channel is processed, or a time division multiplex approach is used to process both I and Q-channels. Thus, a single-channel analog processing circuit may be used.

[0025] The I-channel mode is a mode in which only I-channel output is connected to the analog processing circuit and sampled during a pulse of the pulsed operation. This pulse of the pulsed operation is a pulse of transmission using the transmitter.

[0026] The Q-channel mode is a mode in which only Q-channel output is connected to the analog processing circuit and sampled during a pulse of the pulsed operation.

[0027] The dual-channel time division multiplexing mode is a mode in which during each pulse of the pulsed operation the sampling switches between the I-channel output and the Q-channel output.

[0028] The radar sensor can be switched among these three modes under different working conditions. In particular, the mode is selected automatically based on an interference analysis and / or a signal to noise ratio analysis.

[0029] In this way, when the prevailing conditions permit, the radar sensor can be used in a more efficient single-channel mode. When there is interference, false detections may be reduced by operating in a dual-channel time division multiplex mode.

[0030] The analog front-end for example has a power supply input and an enable input by which the RF transmitter is enabled or disabled, wherein the switch arrangement comprises: a power supply switch between a power supply and the power supply input of the analog front end; an enable switch connected to the enable input; and a sample and hold switch that is part of the analog processing circuit.

[0031] This switch arrangement enables the pulsed operation to be implemented.

[0032] The radar sensor may further comprise a controller for controlling the mode in which the mode switch is used. The controller then controls the mode in which the mode switch is used based on an interference analysis or based on a signal to noise ratio analysis.

[0033] In one example, the controller is configured to: 2024PF80303

[0034] 5 apply the third mode and perform a signal to noise ratio comparison between the I-channel and the Q-channel; and apply the first mode or the second mode to select the I-channel or Q-channel with higher signal to noise ratio.

[0035] This use of the third mode is for example made when the radar sensor is initially turned on, so that a better choice can be made between the I-channel and the Q- channel.

[0036] The controller is then configured to: test for interference when operating in the (chosen one of the) first mode or the second mode; and when interference is not detected, perform motion detection under the first mode or the second mode.

[0037] Thus, in the absence of interference (by which is meant an interference measure is below a threshold), power-efficient single-channel operation is used.

[0038] The controller may be configured, when interference is detected in the first mode or the second mode, to: apply the third mode; perform motion detection under the third mode.

[0039] Thus, the dual-channel time division multiplex mode is used when there is interference. This provides better anti-interference operation for good motion detection performance.

[0040] The controller is for example configured to: test for interference when operating in the third mode; remain in the third mode when interference is detected; and return to the selection of the first mode or the second mode to select the I- channel or Q-channel with higher signal to noise ratio when interference is not detected.

[0041] Thus, when interference has passed, the mode is switched to the singlechannel operation, again testing for the most appropriate channel.

[0042] This disclosure also provides a method of controlling a radar sensor, the radar sensor comprising an analog front-end comprising a transmitter and receiver, the analog front-end comprising an in-phase, I, channel output and a quadrature-phase, Q, channel output, wherein the method comprises: operating the analog front-end in a pulsed operation; and selecting a mode comprising one of: 2024PF80303

[0043] 6 a first, I-channel, mode for performing motion detection using the I-channel output; a second, Q-channel, mode for performing motion detection using the Cochannel output; and a third, dual-channel time division multiplexing, mode for performing motion detection using the I-channel and the Q-channel outputs.

[0044] The method may comprise: applying the third mode and performing a signal to noise ratio comparison between the I-channel output and the Q-channel output; and applying the first mode or the second mode to select the I-channel or Q- channel with higher signal to noise ratio.

[0045] The method may also comprise: testing for interference when operating in the first mode or the second mode; and when interference is not detected, performing motion detection under the first mode or the second mode.

[0046] When interference is detected, the method comprises: applying the third mode; performing motion detection under the third mode.

[0047] When in the third mode, the method comprises: testing for interference; remaining in the third mode when interference is detected; and returning to the selection of the first mode or the second mode to select the I- channel or Q-channel with higher signal to noise ratio when interference is not detected.

[0048] The invention also provides a computer program comprising computer program code which is adapted, when said program is run on the controller of the radar sensor defined above, to perform the method as defined above.

[0049] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment s) described hereinafter.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS

[0051] For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which: 2024PF80303

[0052] 7

[0053] Fig. 1 shows a first known radar sensor;

[0054] Fig. 2 shows a timing diagram for the operation of the radar sensor of Fig. 1;

[0055] Fig. 3 shows a second known radar sensor;

[0056] Fig. 4 shows a timing diagram for the operation of the radar sensor of Fig. 3;

[0057] Fig. 5 shows a radar sensor according to this disclosure;

[0058] Fig. 6 shows a timing diagram for a single-channel operation mode for the I- channel only;

[0059] Fig. 7 shows a timing diagram for a single-channel operation mode for the Q-channel only;

[0060] Fig. 8 shows a timing diagram for a dual-channel time division multiplex operation mode for the I and Q-channels; and

[0061] Fig. 9 shows a method of operating the radar sensor.

[0062] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0063] The invention will be described with reference to the Figures.

[0064] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0065] The invention provides a radar sensor that has a radar analog front-end with an in-phase, I, channel output and a quadrature-phase, Q, channel output. The radar sensor operates in a pulsed operation. A mode switch is used to couple a selected one of the I- channel and Q-channel outputs to an analog processing circuit. The mode switch is operable in a first, I-channel, mode, a second, Q-channel, mode, and a third, dual-channel time division multiplexing, mode. In this way, the radar can operate in power efficient singlechannel mode or a dual-channel mode for greater robustness to interference.

[0066] Figure 1 shows a first known radar sensor 100 which makes use of a dual -band radar forming part of an analog front-end 110. 2024PF80303

[0067] 8

[0068] The radar 110 comprises a radar transmitter 111, a radar receiver 112 and control circuitry 113. It is noted that these components are not shown in later figures simply for reasons of clarity.

[0069] The radar generates in-phase (I) and quadrature-phase (Q) channel signals. These will be referred to as the I-channel and the Q-channel.

[0070] The I-channel and Q-channel are provided to an analog conditioning circuit 120. The circuit 120 comprises an amplifier and band pass filter 122 and a sample and hold circuit 124 for the Q-channel, and a separate amplifier and band pass filter 123 and a separate sample and hold circuit 125 for the I-channel. The sample and hold circuits prepare the channels for analog to digital conversion. Thus, two sets of duplicated analog processing circuits are used to collect the I-channel and the Q-channel almost simultaneously and independently.

[0071] The radar operates in pulsed operation. For this purpose, there is a power supply input (the port labelled Vcc) to the analog front-end 110 and an enable input Tx on by which the RF transmitter 111 is enabled or disabled.

[0072] A power supply switch 116 is provided between a power supply Vcc and the power supply input of the analog front-end, and an enable switch 118 is connected to the enable input. The power supply of the radar front-end can be switched on and off via the power supply switch. The enable switch 118 either routes the power supply Vcc to the enable input or leaves the enable input floating. When the power supply Vcc is provided to the enable input, the transmitter is enabled. The power supply Vcc thereby functions as a logic high for the enable switch 118. RF transmission is stopped when the enable input Tx on is at logic low and RF transmission starts when it is at logic high.

[0073] A controller 130 controls the switches 116 and 118 and the sample and hold circuits 124, 125. The power supply switch 116 is controlled by signal "switch_Vcc", the enable switch 118 is controlled by signal "switch Tx on", and the sample and hold switch is controlled by signal "switch_S&H".

[0074] Figure 2 shows a timing diagram for the operation of the radar sensor of Figure 1. It shows the signals switch Vcc, switch Tx on, and switch_S&H as well as the ADC clock signal.

[0075] The power supply switch is first turned on by switch_Vcc. A delay is then imposed before the enable switch is turned on by switch Tx on. This delay provides an IC settling time (shown as ICS) for the control circuit 113 of the analog front end. After a further delay, the sample and hold is switched to sample the I-channel and Q-channel. This delay 2024PF80303

[0076] 9 provides a signal stabilization time (shown as SST) after initially turning on the transmitter and before sampling takes place. After a further delay, the I-channel sample and Q-channel sample are outputted. This delay is an analog to digital converter settling time (shown as ADCS).

[0077] The transmitter is then disabled, and the power supply is switched off shortly after.

[0078] The main problem with this approach is the duplication of sensor hardware, which will increase the sensor size and cost. For some luminaires, there is a limitation on the space to integrate the sensor such that independent I-channel and Q-channel analog baseband processing is not possible at the same time. In such cases, it is required to keep only one set of the analog baseband processing circuits, for either the I-channel or the Q-channel.

[0079] Figure 3 shows an approach using time division multiplexing (TDM) so that a single-channel analog processing circuit is used for processing both the I -channel and Q- channel.

[0080] The same references are used as in Figure 1.

[0081] The analog conditioning circuit 120 now comprises a single amplifier and band pass filter 122 and a single sample and hold circuit 124, that is used at different times for the I-channel and Q-channel. A third switch 119 performs the multiplexing operation, controlled by signal "switch_3" from the controller 130. It alternates between switching the I- channel and the Q-channel to the analog conditioning circuit 120, thereby implementing a time division approach.

[0082] Time division multiplexing is widely used in communication. The I-channel signal and Q-channel can be collected sequentially by switching the signal provided to the single set of analog processing circuits.

[0083] Figure 4 shows a timing diagram for the operation of the radar sensor of Figure 3. It again shows the signals switch Vcc, switch Tx on, and switch_S&H as well as the ADC clock signal. It also shows the multiplex control signal switch_3.

[0084] The power supply switch is first turned on by switch_Vcc. A delay is then imposed before the enable switch is turned on by switch Tx on.

[0085] As explained above, this delay provides an IC settling time ICS. After a further delay (signal stabilization time SST I for the I-channel), the sample and hold circuit tis switched to sample the I-channel. The I-channel sample is output after the analog to digital converter settling time ADCS. 2024PF80303

[0086] 10

[0087] The multiplexing switch is then switch by signal switch_3 so that the Cochannel can be sampled. There is first the signal stabilization time SST Q for the Q-channel, followed by the sample and hold switching again. The Q-channel sample is output after the analog to digital converter settling time ADCS.

[0088] The transmitter is then disabled, and the power supply is switched off shortly after.

[0089] The main problem with this approach is the longer operation time, and hence power consumption, resulting from the required signal stabilization and ADC settling time delays, in order to ensure no distortion on both the I-channel and Q-channel. This will result in larger duty cycle (if the same duty cycle frequency is used), and cause more power consumption compared to the single-channel operation explained above.

[0090] It would be desirable to enable a pulsed operation of a radar sensor with dualchannel operation and which only needs a single-channel analog baseband processing circuit (to enable size and cost reduction), but which can achieve a lower power consumption compared to conventional TDM radar.

[0091] Figure 5 shows an approach according to this disclosure.

[0092] The same references are used as in Figures 1 and 3.

[0093] The hardware is essentially the same as in Figure 3, but the multiplex switch 119 is replaced by a mode switch 140, and the operation of the mode switch 140 by the controller 130 is different to a simple time division multiplex approach.

[0094] The analog conditioning circuit 120 thus again comprises a single amplifier and band pass filter 122 and a single sample and hold circuit 124. The mode switch 140 is controlled by signal "switch ch" from the controller 130. It selectively routes either the I- channel alone or the Q-channel alone to the analog conditioning circuit 120 or it performs a switched time division multiplex approach.

[0095] While processing the I-channel alone, it means each pulse of the pulsed operation involves sampling only of the I-channel data. While processing the Q-channel alone, it means each pulse of the pulsed operation involves sampling only of the Q-channel data. The time division multiplex approach involves sampling both I-channel data and Q- channel data within a single pulse of the pulsed operation. Thus, in the single-channel mode, there is no switching between the I-channel and Q-channel during each pulse of the pulsed operation of the radar sensor.

[0096] The radar sensor thus uses the mode switch 140 to switch between a singlechannel (SC) operation mode and a dual-channel time division multiplexing (TDM) 2024PF80303

[0097] 11 operation mode under different working conditions. In particular, dual-channel operation is used when interference is high because a dual-channel mode is more robust to interference. When in single-channel mode, the channel to be employed is based on signal to noise ratio (SNR) considerations.

[0098] The mode switch is thus used to choose to connect the I-channel raw signal or the Q-channel raw signal from analog front-end 110 to the single-channel analog baseband processing circuit.

[0099] During the TDM mode, a SNR comparison may be made between the I- channel and the Q-channel, so that an automatic selection can be made of the channel with the better SNR to be used for a next single-channel operation of the radar sensor.

[0100] The power savings are obtained because most of the time the radar sensor can be operated using the single-channel mode of operation, for motion detection.

[0101] The dual-channel TDM mode is for example used under two conditions:

[0102] (i) A self-diagnostic mode for channel auto-selection

[0103] A self-diagnostic mode is used for the SNR comparison between the I-channel and Q-channel as mentioned above. The channel with better SNR can then be auto-selected by the radar sensor itself and used for an upcoming single-channel operation mode. This may for example happen when the sensor powers on at start up, but there are other options to trigger a channel auto-selection;

[0104] (ii) Anti-interference

[0105] If significant interference on the radar signal has been identified during a period of single-channel operation, the sensor may be controlled to enter the TDM mode to perform interference removal and motion detection via the dual-channel mode, with I- channel and Q-channel signal processing. The radar sensor can remain in the dual-channel mode while interference remains. Thus, a switch back to the single-channel mode may take place when interference is no longer identified.

[0106] In this way, the radar sensor can work mainly with single-channel operation for lower power consumption, can also perform auto-channel selection (when in singlechannel mode) and can be operated in dual-channel mode for improved interference robustness to enable improved motion detection performance.

[0107] It will thus be clear that are three main operation modes that can be realized via the radar sensor of Figure 5.

[0108] Figure 6 shows the timing diagram for the first mode, namely a single-channel operation mode for the I-channel only. It shows the signals switch Vcc, switch Tx on, and 2024PF80303

[0109] 12 switch_S&H as well as the ADC clock signal and also the control signal switch ch for the mode switch 140.

[0110] For this mode, the mode switch 140 continuously connects to the I-channel without switching. The mode switch signal switch ch is a constant value for this purpose.

[0111] As in Figures 2 and 4, the power supply switch is first turned on by switch Vcc. An IC settling delay ICS is then imposed before the enable switch is turned on by switch Tx on. The sample and hold circuit is then switched to sample the I-channel, after the signal stabilization time SST I. After the ADC settling time ADCS, the I-channel sample is outputted.

[0112] The transmitter is then disabled, and the power supply is switched off shortly after.

[0113] This timing is for a single duty cycle, and it repeats. For each pulsed operation of the transmitter there is only I-channel data sampled while the radar sensor remains in the first mode. The first mode preferably comprises multiple such duty cycles.

[0114] Figure 7 shows the timing diagram for the second mode, namely a singlechannel operation mode for the Q-channel only. It shows the same signals as Figure 6.

[0115] For this mode, the mode switch 140 continuously connects to the Q-channel without switching. The mode switch signal switch ch is a different constant value for this purpose.

[0116] As in Figure 6, the power supply switch is first turned on by switch_Vcc. An IC settling delay ICS is then imposed before the enable switch is turned on by switch Tx on. The sample and hold circuit is then switched to sample the Q-channel, after the signal stabilization time SST Q. After the ADC settling time ADCS, the Q-channel sample is outputted.

[0117] The transmitter is then disabled, and the power supply is switched off shortly after. For each pulsed operation of the transmitter there is only Q-channel data sampled. Again, the second mode preferably comprises multiple such duty cycles.

[0118] Figure 8 shows the timing diagram for the third mode, namely a dual-channel TDM operation mode for the I and Q-channels. It shows the same signals as Figures 6 and 7.

[0119] The timing is the same as Figure 4. The channel switch 140 functions in the same way as the third switch of Figure 3. For each duty cycle, a switch is made from the first channel to the second channel after the first sampling has been completed. There is a switch back after the second sampling is completed. 2024PF80303

[0120] 13

[0121] The first channel is for example a preferred channel, for example based on the SNR analysis mentioned above. Thus, the signal switch ch is first allocated to the preferred channel, which is the same channel as was used in the last single-channel operation mode. Figure 8 shows the timing when the preferred channel is the I-channel.

[0122] There are now two ADC sampling functions carried out sequentially within each pulse of the pulsed operation of the transmitter.

[0123] The radar sensor can carry out both motion detection and interference detection when operating in each mode. Of course, the motion detection when operating in a single-channel operation mode can only be based on the signal from the selected single channel and thus has more risk of false triggers from interference. The motion detection when operating in the TDM dual-channel operation mode can be based on the dual I-channel and Q-channel signals and is thus more powerful for anti-interference.

[0124] Figure 9 shows a method of operating the radar sensor.

[0125] The radar sensor is powered in step 200.

[0126] When initially powered on, the dual-channel mode is used by default. This means both I and Q-channels can be analyzed. In particular, the SNR for each channel can be made in step 202, and the best channel is selected (with the higher SNR). The mode then switches to the single-channel mode.

[0127] In this way, the suitable channel to be operated for the single-channel operation is selected.

[0128] While in the single-channel mode, interference detection takes place in step 204.

[0129] Interference analysis for the last period takes place in step 206. If interference is not detected (i.e., interference is assessed to be below a threshold in step 206), motion detection takes place in step 208 using the currently selected channel.

[0130] If motion detection detects motion, a motion signal is generated in step 212. This is then for example used to control a luminaire (or HVAC system or other system in which the radar sensor is integrated).

[0131] If motion detection does not detect motion, the method loops back to the interference analysis of step 206. While interference is not detected, the radar sensor remains in the single-channel mode of operation.

[0132] When interference is detected in step 206 (i.e., interference is assessed to be above a threshold), the radar sensor is switched to the dual-channel TDM mode, and interference detection takes place for both channels in step 222. 2024PF80303

[0133] 14

[0134] Dual-channel motion detection takes place in step 224.

[0135] If motion detection detects motion, a motion signal is generated in step 212. This is then for example used to control a luminaire.

[0136] If motion detection does not detect motion, the method loops back to a step 220 where interference analysis takes place to determine if interference was detected in the last period. While interference remains detected, the radar sensor remains in the dual-channel mode of operation.

[0137] When interference is no longer detected in step 220 (i.e., interference has dropped below a threshold), the radar sensor is switched to the single-channel mode, but SNR comparison is first made of both channels (in step 202) so that the best channel for singlechannel operation is first determined.

[0138] In this way, the radar sensor is operated in one of a first, I-channel, mode for performing motion detection using the I-channel, a second, Q-channel, mode for performing motion detection using the Q-channel, and a third, time division multiplexing, mode for performing motion detection using the I-channel and the Q-channel.

[0139] It can be seen that the mode in which radar sensor is operated (by the mode switch) is based on an interference analysis and a signal to noise ratio analysis. When there is no interference detected under either the single-channel mode or the dual-channel TDM mode, the sensor will maintain with single-channel operation for motion detection in order to achieve power savings. In this way, the radar sensor can work mainly using the singlechannel mode (with automatic channel selection) but is still capable of anti-interference via the dual-channel TDM operation for improved motion detection performance.

[0140] The approach is for example for use in luminaire integration. The pulsed operation with the ability for I-channel or Q-channel signal processing or TDM processing of both channels enables both power budget requirements and anti-interference requirements to be met. In particular, a balance is made between the power consumption of the pulsed operation and the anti-interference capability via the I and Q dual-channel based signal processing.

[0141] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0142] Functions implemented by a processor may be implemented by a single processor or by multiple separate processing units which may together be considered to 2024PF80303

[0143] 15 constitute a "processor". Such processing units may in some cases be remote from each other and communicate with each other in a wired or wireless manner.

[0144] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0145] If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to". If the term "arrangement" is used in the claims or description, it is noted the term "arrangement" is intended to be equivalent to the term "system", and vice versa.

[0146] Any reference signs in the claims should not be construed as limiting the scope.

Claims

2024PF8030316CLAIMS:

1. A radar sensor, comprising; a radar analog front-end (110) comprising a transmitter (111) and receiver (112), the analog front-end comprising an in-phase, I, channel output and a quadrature-phase, Q, channel output; an analog processing circuit (120) for processing either the I-channel or Cochannel output; a switch arrangement (116, 118, 124) for enabling a pulsed mode of operation; and a mode switch (119) between the analog front-end and the analog processing circuit, wherein the mode switch (119) is for coupling a selected one of the I-channel and Q-channel outputs to the analog processing circuit, wherein the mode switch is operable in: a first, I-channel, mode; a second, Q-channel, mode; and a third, time division multiplexing, mode; wherein the radar sensor further comprises a controller (130) for controlling the mode in which the mode switch is used and the controller is configured to: apply the third mode and perform a signal to noise ratio comparison between the I-channel and the Q-channel; and apply the first mode or the second mode to select the I-channel or Q-channel with higher signal to noise ratio.

2. The radar sensor of claim 1, wherein the analog front-end has a power supply input (Vcc) and an enable input (Tx on) by which the RF transmitter is enabled or disabled, wherein the switch arrangement comprises: a power supply switch (116) between a power supply and the power supply input of the analog front end; an enable switch (118) connected to the enable input; and2024PF8030317 a sample and hold switch (124) that is part of the analog processing circuit.

3. The radar sensor of claim 1 or 2, wherein the controller (130) is configured to control the mode in which the mode switch (119) is used based on an interference analysis.

4. The radar sensor of claim 1 or 2, wherein the controller (130) is configured to control the mode in which the mode switch (119) is used based on a signal to noise ratio analysis.

5. The radar sensor of claim 1 or 2, wherein the controller (130) is configured to: test for interference when operating in the first mode or the second mode; and when interference is not detected, perform motion detection using the first mode or the second mode.

6. The radar sensor of claim 5, wherein the controller (130) is configured, when interference is detected, to: apply the third mode; perform motion detection using the third mode.

7. The radar sensor of claim 6, wherein the controller (130) is configured to: test for interference when operating in the third mode; remain in the third mode when interference is detected; and return to the selection of the first mode or the second mode to select the I- channel or Q-channel with higher signal to noise ratio when interference is not detected.

8. A method of controlling a radar sensor, the radar sensor comprising a radar analog front-end (110) comprising a transmitter (111) and receiver (112), the analog frontend (110) comprising an in-phase, I, channel output and a quadrature-phase, Q, channel output, wherein the method comprises: operating the radar sensor in a pulsed operation; and selecting a mode comprising one of: a first, I-channel, mode for performing motion detection using the I- channel;2024PF8030318 a second, Q-channel, mode for performing motion detection using the Q-channel; and a third, time division multiplexing, mode for performing motion detection using the I-channel and the Q-channel; wherein the method further comprises: applying (202) the third mode and perform a signal to noise ratio comparison between the I-channel and the Q-channel; and applying (204) the first mode or the second mode to select the I-channel or Q- channel with higher signal to noise ratio.

9. The method of claim 8, comprising: testing (206) for interference when operating in the first mode or the second mode; and when interference is not detected, performing (208) motion detection using the first mode or the second mode.

10. The method of claim 9, comprising, when interference is detected: applying (224) the third mode; performing (224) motion detection using the third mode.

11. The method of claim 10, comprising: testing (222) for interference when operating in the third mode; remaining (224) in the third mode when interference is detected; and returning to the selection of the first mode or the second mode to select the I- channel or Q-channel with higher signal to noise ratio when interference is not detected.

12. A computer program comprising computer program code which is adapted, when said program is run on the controller of the radar sensor of any of claims 1 to 7, to perform the method of any one of claims 8 to 11.

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