Systems and methods for detecting heart rate and respiration rate

Abstract

A system for measuring respiration rate and / or heart rate of a subject remotely includes a transmitter that is configured to transmit an ultra-wide band (UWB) frequency modulated pulse radar signal to

Description

FIELD Embodiments described herein relate to systems and methods for detecting heart rate and respiration rate of a subject. BACKGROUND Vital signs that measure the body’s basic functions are important for monitoring and detecting medical problems in humans and other animals. These vital signs include heart rate ( / .e., a measure of the number of times a heart beats per minute) and respiration rate (i.e., a measure of the number of breaths a human or an animal takes per minute). Conventionally, contact type techniques (e.g., using hands or stethoscope) have been used to measure heart rate and respiration rate in humans and in other animals. However, relying on contact with a subject (e.g., humans or other animals) to measure vital signs of the subject can be challenging. For example, requiring contact to measure vital signs can make it challenging to monitor the health of a subject (e.g., humans or other animals) remotely. As another example, requiring contact to measure vital signs of a non-human animal can be challenging because of their sudden unpredictable movements. More recently, some non-contact type techniques to measure heart rate and respiration rate are being explored. These techniques include visual inspection of a subject (e.g., humans or other animals) within a given timeframe, using video, using thermal infrared, etc. However, existing non-contact type technology suffers from poor resolution and is not portable. Accordingly, there is a need to develop non-contact type technology to measure heart rate and respiration rate of humans and / or other animals. In particular, non-contact technology that is portable and / or has high resolution is desirable. SUMMARY Disclosed herein are systems and methods for measuring respiration rate and heart rate of a subject remotely. In some variations, a system for measuring respiration rate and heart rate can comprise a transmitter that is configured to transmit an ultra-wide band frequency modulate pulse radar signal towards a subject, at least one receiver that is configured to receive a reflected portion of the ultra-wide band frequency pulse radar signal, and a controller that is configured to - determine a position of the subject based at least in part on the reflected portion of the ultra-wide band frequency modulated pulse radar signal, and determine the respiration rate and / or the heart rate of the subject based on the determined position of the subject. In some variations, the at least one receiver can comprise a plurality of receivers. Each receiver of the plurality of receivers can be configured to receive a corresponding reflected portion of the ultra-wide band frequency modulated pulse radar signal. In some variations, the controller can be configured to: determine a three-dimensional position, velocity, and acceleration of the subject based at least in part on the corresponding reflected portion of the ultra-wide band frequency modulated pulse radar signal from each receiver of the plurality of receivers, and determine the respiration rate and the heart rate of the subject based on the determined three-dimensional position, velocity, and acceleration. In some variations, the controller can be further configured to: decorrelate the reflected portion of the ultra-wide band frequency modulated pulse radar signal from the transmitted signal to produce a decorrelated signal, estimate a frequency variation of the decorrelated signal with time, and determine the position of the subject based on the decorrelated signal and the estimated frequency variation. In some variations, the controller can be further configured to mask the estimated frequency variation using the decorrelated signal. In some variations, the controller can be configured to: determine a change in position of the subject over time, and apply Fast Fourier Transform on the change in position to determine the heart rate and the respiration rate of the subject. In some variations, the controller can be further configured to generate the ultra-wide band frequency modulated pulse radar signal. The controller can be configured to modify the generated ultra-wide band frequency modulated pulse radar signal on-the-fly. In some variations, the controller can be further configured to: generate an in-phase pulse, generate a quadrature phase pulse, and combine the in-phase pulse and the quadrature phase pulse, thereby generating the ultra-wide band frequency modulated pulse radar signal. In some variations, the transmitter can be positioned in a first device and the at least one receiver is positioned in a second device different from the first device. In some variations, the transmitter and the at least one receiver can be positioned in a same device. The system can further comprise at least one sensor to measure a change in motion of the device. The controller can be configured to determine the position of the subject based on the reflected portion of the ultra-wide band frequency modulated pulse radar signal and the change in motion of the device. In some variations, the at least one sensor can include at least one of a gyroscope and an accelerator. The device can be a portable device. In some variations, the system can be configured to determine the heart rate and the respiration rate of a subject positioned between a distance of about 0.25m and about 10m from the system. In some variations, a method can comprise transmitting an ultra-wide band frequency modulated pulse radar signal towards a subject, receiving a reflected portion of the transmitted signal, determining, via a controller, a position of the subject based at least in part on the reflected portion, and determining, via the controller, a respiration rate and heart rate of the subject based on the determined position. BRIEF DESCRIPTION OF DRAWINGS Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: FIG. 1 shows a schematic of a system according to an embodiment; FIG. 2 shows a schematic of a portion of a controller of the system in FIG. 1 according to an embodiment; FIG. 3A and FIG. 3B shows an example of a frequency modulated pulse radar signal without an envelope; FIG. 4A and FIG. 4B shows an example of a frequency modulated pulse radar signal with an envelope; FIG. 5 is a flowchart of an example method to control the transmission of the frequency modulated pulse radar signals; FIG. 6 shows an example decorrelated signal and an estimated frequency variation with time signal; FIG. 7A shows an example signal representing the change in distance of a subject over time; FIG. 7B shows a transformed signal in a frequency domain following the application of Fast Fourier Transform; FIG. 8A and FIG. 8B show example configurations for a transmitter and multiple receivers that can be included in the system; FIG. 9 is a flowchart showing an example method for detecting heart rate and / or respiration rate of one or more subjects; FIG. 10 is a flowchart showing an example method for accumulating in-phase components and the quadrature phase components of each received signal. DETAILED DESCRIPTION As used herein, the term “subject” refers to mean any animal, including but not limited to, mammals such as for example, humans, rodents, bats, primates, even-toed ungulates, carnivora, and / or the like. Disclosed herein are systems and methods for detecting heart rate and / or respiration rate of one or more subjects. In particular, the technology disclosed herein provides a high resolution, portable, non-contact type approach to monitoring and detecting heart rate and / or respiration rate of one or more subjects. At a high-level, the technology disclosed herein can be configured to generate an ultra-wide band (UWB) frequency modulated pulse radar signal dynamically and on-the-fly. This UWB frequency modulated pulse radar signal can be transmitted towards a subject. The subject may reflect either a whole or a portion of the UWB frequency modulated pulse radar signal. This reflected signal can be received and can be used to measure at least one of a distance (e.g., range) of the subject and / or velocity of the subject. The respiration rate and the heart rate of the subject can be determined based on the distance and / or velocity of the subject. In some variations, the technology disclosed herein may incorporate one or more sensors (e.g., accelerometers, gyroscopes, etc.) to correct for a motion of the subject. Furthermore, the technology disclosed herein provides for multiple redundancies in determining the distance and / or the velocity, consequently improving the accuracy and the resolution of the heart rate and the respiration rate. FIG. 1 shows an example schematic of a system 100 for detecting heart rate and / or respiration rate of one or more subjects remotely. The system 100 comprises a controller 104 that is communicably coupled to a user interface 102 and to one or more sensor(s) 110. The controller 104 is coupled (e.g., electronically coupled) to a transmitter 106 and to one or more receivers (e.g., receivers 108a, 108b, ... 108n) collectively referred to herein as “receiver 108”. Although the technology disclosed herein is described using a single transmitter 106, this technology can be readily extended to a system with more than one transmitter 106. The transmitter 106 can be any suitable type of radar transmitter configured to transmit frequency modulated pulse radar signals. For instance, the transmitter 106 may include a transmitter antenna to transmit the frequency modulated pulse radar signals towards one or more subjects. The receiver 108 can be any suitable type of radar receiver configured to receive a reflected portion of the transmitted frequency modulated pulse radar signals (e.g., portion of the transmitted frequency modulated pulse radar signals that are reflected from the subject). For instance, the receiver 108 may include a receiver antenna to receive the reflected portion of the frequency modulated pulse radar signals. The system 100 can include any suitable number of receivers 108 such as for example, one receiver, two receivers, three receivers, four receivers, five receivers, etc. More specifically, in some variations, the system 100 may include a single receiver 108. Alternatively, the system 100 may include more than one receivers 108. In some variations, the transmitter 106 and the receiver 108 may be positioned substantially close to each other (e.g., proximate to each other). For instance, the transmitter 106 and the receiver 108 may be co-located within a same physical device. In other variations, the transmitter 106 and the receiver 108 may be positioned at a distance from each other. For instance, the transmitter 106 and the receiver 108 may be located within separate physical devices. The transmitter 106 and the receiver 108 are electronically coupled to the controller 104. The controller 104 can be configured to generate frequency modulated pulse radar signals that are transmitted via the transmitter 106. The controller 104 may generate the frequency modulated pulse radar signals on-the-fly. The frequency modulated pulse radar signals generated by the controller 104 may be ultra-wide band (UWB) frequency modulated pulse radar signals. The use of UWB frequency modulated pulse radar signals can facilitate determining heart rate and / or respiration rate of subject(s) who may be positioned substantially close to the receiver (e.g., within a distance of about 0 m from the receiver 108, as long as the subject and the receiver 108 are not in contact). In some variations, the controller 104 can include one or more electronic circuits to generate the frequency modulated pulse radar signals. The electronic circuits may include one or more components such as waveform generator(s), filter(s), oscillator(s), digital-to-analog converter(s), amplifier(s), and / or the like. FIG. 2 shows an example schematic of a portion 104’ of a controller 104 used to generate the frequency modulated pulse radar signals on-the-fly. A waveform generator (not shown in FIG. 2) may be configured to generate an in-phase (I) pulse and a quadrature-phase (Q) pulse. A first digital-to-analog converter 212a may convert the in-phase pulse into a first analog signal and a second digital-to-analog converter 212b may convert the quadrature-phase pulse to a second analog signal. A local oscillator 214 may generate a carrier wave. A 90 degree phase shift at 216 is applied to the carrier wave. The first analog signal is modulated with the phase unshifted carrier wave and the second analog signal is modulated with the phase shifted carrier wave. The modulated signals can be combined to generate the modulated output 218. In some variations, the portion 104’ of the controller 104 may include an attenuator and / or an amplifier. The attenuator and / or amplifier may be applied to the modulated output 218 before the generated frequency modulated pulse radar signal is transmitted (e.g., via an antenna). In this manner, the amplitude of the generated frequency modulated pulse radar signals can be varied. The controller 104 may further include a processor to control one or more electronic circuits that are included in portion 104’ of the controller 104. The processor may be any suitable processing device configured to run and / or execute a set of instructions or code, and may include one or more data processors, image processors, graphics processing units, physics processing units, digital signal processors, and / or central processing units. The processor may be, for example, a general purpose processor, a Field Programmable Gate Array (FPGA), a logic controller, an Application Specific Integrated Circuit (ASIC), and / or the like. The processor can be configured to control the generation of the frequency modulated pulse radar signals via the one or more electronic circuits. Additionally or alternatively, the processor can be configured to control the transmission of the frequency modulated pulse radar signals via the one or more electronic circuits and the transmitter 106. For example, the processor can be configured to control the attenuator and / or the amplifier to control the amplitude, frequency, and duration of the frequency modulated pulse radar signals. In some variations, the processor can be configured to apply an envelope (e.g., an upper envelope and / or a lower envelope) to the frequency modulated pulse radar signals. FIGs. 3A and FIG. 3B show an example of a frequency modulated pulse radar signal without an envelope. FIGs. 4A and FIG. 4B show an example of a frequency modulated pulse radar signal with an envelope. By applying the envelope and / or by controlling the amplitude, the frequency, and the duration, the processor can vary the shape of the generated frequency modulated pulse radar signals as needed. In some variations, the processor can be configured to control the time interval between transmitting each successive frequency modulated pulse radar signal. FIG. 5 is a flowchart of an example method 520 implemented by the controller 104 to control the transmission of the frequency modulated pulse radar signals. As used herein, the term “scan” refers to mean the transmission of a single frequency modulated pulse radar signal towards a subject and the receipt of a reflected portion of the transmitted signal. Put differently, transmitting a first frequency modulated pulse radar signal towards a subject and receiving a reflected portion of the first signal from the subject can constitute a first “scan.” In a similar manner, transmitting a second frequency modulated pulse radar signal towards a subject and receiving a reflected portion of the second signal can constitute a second “scan.” After an initial delay at step 524, the controller 104 can be configured to determine whether to perform a scan (e.g., via the transmitter 106 and receiver 108) for the presence of a subject. If at step 526, the controller 104 determines that a scan is to be performed, then at step 528, the controller 104 controls the electronic devices and the transmitter 106 to transmit a first frequency modulated pulse radar signal. At step 530, the controller 104 controls the transmission of a subsequent frequency modulated pulse radar signal by controlling a time delay between the two consecutive frequency modulated pulse radar signals (i.e., between the first frequency modulated pulse radar signal and a subsequent second frequency modulated pulse radar signal). Put differently, the controller 104 may determine a time duration that is to elapse before a subsequent frequency modulated pulse radar signal is to be transmitted. Following the time delay, the controller 104, continues to perform the scan if needed. That is, the controller 104 may iteratively execute the steps 526, 528, and 530, until the scans needed for a sample are performed. As used herein, the term “sample” refers to mean a predefined number of scans. As an example, consider that six scans are defined as the number of scans needed to generate a “sample.” In such an example, a first six scans performed by the system 100 can constitute a “first sample.” The next consecutive six scans performed by the system 100 can constitute a “second sample.” Therefore, at step 526, if the controller 104 determines that the number of scans needed to generate a sample have been performed, then at step 532, the controller 104 stops the transmission of the frequency modulated pulse radar signals. The controller 104 then executes the initial time delay at 524 before generating the next subsequent sample. The controller 104 can control the transmission of the frequency modulated pulse radar signals by controlling: the time between two consecutive samples (e.g., initial delay 524), the time between two consecutive scans (e.g., delay 530), and / or the sampling time period. These time periods can be inter-dependent as seen in the following equation, T=(NXTS) + Td where T represents the sampling period, N represents the number of scans, Ts represents the time between two consecutive scans, and Td represents the time between two consecutive samples (e.g., the initial time delay 524). Therefore, the controller can control the transmission of the frequency modulated pulse radar signals by controlling one or more of: T, Ts, or Td. In some variations, the controller 104 can be configured to dynamically modify the transmission of the frequency modulated pulse radar signals on-the-fly. For example, the controller 104 can modify one or more of: T, Ts, or Td on-the-fly. Additionally or alternatively, the controller 104 can be configured to modify the amplitude and / or the frequency of the frequency modulated pulse radar signals on-the-fly. In particular, the controller 104 may be configured to implement a feedback loop to dynamically modify the transmission of the frequency modulated pulse radar signals on-the-fly. For instance, the controller 104 may analyse reflected portions of prior transmitted frequency modulated pulse radar signals. Based on this analysis, the controller can vary the amplitude of a subsequent signal, a duration of a subsequent signal, a frequency of a subsequent signal, and / or the one or more of: T, Ts, or Td, for example, to optimize subsequent received signals that are received at the receiver 108. That is, the controller 104 can dynamically modify the transmission of the frequency modulated pulse radar signals based on an analysis of the prior received signals so as to optimize the subsequent received signals (e.g., quality and / or quantity of the received signals). In some variations, the controller 104 can be configured to continuously monitor the received signals so as to modify the subsequent signals that are to be transmitted. Accordingly, the controller 104 can fine-tune the frequency modulated pulse radar signals and / or the transmission of frequency modulated pulse radar signals as needed and on-the fly. Modifying the frequency modulated pulse radar signals dynamically and on-the-fly can be advantageous. Firstly, the duty cycle of the system 100 can be controlled by controlling the gain and / or duration of the frequency modulated pulse radar signals, and / or the gain and / or duration of the received reflected signal. This can facilitate power management such that the system 100 uses less power. Secondly, the system 100 can be configured to detect and monitor the heart rate and / or the respiration rate of multiple subjects. For instance, the system 100 can modify the frequency modulated pulse radar signal that is transmitted to each subject. In some variations, the power of the system 100 can be optimized based on the received reflected signals. The difference in the gain and / or duration of the transmitted signals can allow the system 100 to differentiate between the different subjects. Thirdly, the system 100 can be adapted such that the system 100 can meet various regulatory requirements as needed. The use of the pulse radar signal enables the system 100 to use less power in comparison to a system that may use continuous frequency modulated signals. As discussed above, the controller 104 may be configured to transmit, via the transmitter 106, the frequency modulated pulse radar signals towards one or more subjects. The subject(s) may reflect the whole or a portion of the transmitted frequency modulated pulse radar signals. The reflected portion of the transmitted frequency modulated pulse radar signals may be received at the receiver 108. The controller 104 may be configured to capture the reflected portion of the transmitted signal within a given time frame after the transmission of the signal towards a subject. The controller 104 may be configured to analyse reflected portions of the transmitted frequency modulated pulse radar signals so as to determine the heart rate and / or the respiration rate of the one or more subjects. In some variations, the controller 104 can include further electronic circuits that are configured to: amplify the received signals ( / .e.. the reflected portion of the transmitted signals), convert the received signals into a digital signal, and / or decorrelate the received signals from the transmitted signals. For example, the electronic circuits may include an attenuator and / or an amplifier to control the gain of each of the received signal. The one or more electronic circuits included in the controller 104 may capture the in-phase (I) component and the quadrature phase (Q) component of each received reflected portion of the frequency modulated pulse radar signals. The in-phase component and the quadrature phase component of each signal can be captured separately. For instance, each received reflected portion of the frequency modulated pulse radar signal may be separated into a first signal that is representative of the in-phase component of that received reflected portion and a second signal that is representative of the quadrature phase component of that received reflected portion. The first signal and the second signal are captured separately. To capture the first signal and the second signal (separately), each of the first signal and the second signal can be demodulated (e.g., down-converted) using an oscillator, such as for example, local oscillator 214, thereby generating a first demodulated signal and a second demodulated signal. Each receiver 108 can be coupled to two separate analog-to-digital converters. A first analog-to-digital converter may transform the first demodulated signal to the digital domain and the second analog-to-digital converter may transform the second demodulated signal to the digital domain. In this manner, the in-phase component and the quadrature phase component of each received signal are captured separately. Each of the captured in-phase (I) component and the quadrature phase (Q) component of each received signal can be accumulated. For example, FIG. 10 is a flowchart showing an example process of accumulating the in-phase components and the quadrature phase components of the received signals. As seen in FIG. 10, at 1084, the method includes receiving an indication (e.g., in the form of a signal) that a frequency modulated pulse radar signal has been transmitted towards a subject. At 1086, the method includes demodulating (e.g., via an oscillator) the in-phase component and the quadrature phase component of the received reflected portion of the transmitted signal. The method further includes capturing (e.g., using a respective analog-to-digital converter) the demodulated in-phase component and the quadrature phase component separately. At 1088, the method includes accumulating (e.g., summing) the in-phase component and the quadrature phase component separately. At 1090, the method includes determining whether the accumulation should be continued. For example, if the number of scans to generate a sample have been performed, then the method determines that the accumulation can be stopped. In such a scenario, the method at 1902 outputs the accumulated in-phase components (i.e., an in-phase sample) and the accumulated quadrature phase components ( / .e., a quadrature phase sample) separately. These accumulated signals are used to determine the position of the subject from the system 100. If enough number of scans have not been performed to generate a sample, then the steps 1084, 1086, 1088, and 1090 can be repeated. In this manner, the in-phase components and the quadrature phase components can be accumulated (e.g., summed) separately. The accumulated in-phase components (e.g., accumulated first signals) and the accumulated quadrature phase components (e.g., accumulated second signals) that are outputted at 1092 can be used to determine a change in distance (e.g., range) of the subject from system 100. For example, a change in the accumulated first signal and a change in the accumulated second signal can be used to calculate a change in distance of the subject from the system 100. It should be readily understood that the distance is calculated from a predetermined origin coordinates of the system 100. For example, in some variations, the transmitter 106 may be considered as the origin. In such variations, the change in the distance of the subject may be a change in the distance from the transmitter 106. As another example, in variations in which the system 100 includes two transmitters, the origin of the system 100 may be an average position between the two transmitters. In such variations, the change in the distance of the subject may be a change in the distance from the average position between the two transmitters. As a further example, the in-phase components and the quadrature phase components of each of a first set of received signals can be accumulated separately (e.g., until a first sample is generated) to produce first accumulated in-phase component and second accumulated quadrature phase component. Similarly, the in-phase components and the quadrature phase components of each of a second set of received signals can be accumulated separately (e.g., until a second subsequent sample is generated) to produce second accumulated in-phase signal and second accumulated quadrature phase signal. A difference between the second accumulated in-phase signal and the first accumulated in-phase signal and a difference between the second accumulated quadrature phase signal and the first accumulated quadrature phase signal can be used to calculate a change in distance of the subject. This can improve the signal-to-noise ratio of the received signals. To accurately calculate the change in distance of the subject based on a change in the accumulated first signal and a change in the accumulated second signal, the motion of the subject during the timeframe between accumulating the first signal and the second signal should be substantially small. Therefore, to accurately calculate the change in distance, the number of scans for accumulating the signals can be determined based on the maximum possible velocity of the subject. Accordingly, in some scenarios, the controller 104 may be configured to accumulate the captured in-phase signals and the captured quadrature phase signals such that the number of scans for such accumulation may be a single scan. In some variations, the processor may be configured to control the timeframe for accumulating the in-phase components (e.g., first signal) and the quadrature phase components (e.g., second signal). For example, the timeframe for accumulating can be controlled to modify the timeframe so as to reduce the amount of motion of the subject. Furthermore, the timeframe can determine the amount of time the processor has to read the accumulated signals. Therefore, controlling the timeframe enables control of the time that the processor may have to read the accumulated signals. In some variations, controlling the time between two consecutive accumulations can control the sampling frequency. The accumulated signals can be analyzed by the processor to determine a distance (e.g., range) of the subject from the system 100 (e.g., from the transmitter 106) and / or the velocity of the subject. For example, the processor can be configured to decorrelate the received reflected portion of the signal (e.g., received at the receiver 108) from the transmitted signal that was transmitted by the transmitter 106. Decorrelating the received reflected portion of the signal from the transmitted signal can allow the controller 104 to monitor and detect heart rate and / or respiration rate of multiple subjects simultaneously. For instance, as discussed above, different frequency modulated pulse radar signals can be transmitted to different subjects. Decorrelating the received reflected portion of the signals can allow the processor to identify which received signal corresponds to which subject. The distance and / or velocity of the subject can be determined based on the decorrelated signal. Since the received reflected portion of the signals is accumulated by accumulating the in-phase component and the quadrature phase component separately, there are two decorrelated signals for each transmitted signal (e.g., a first decorrelated signal associated with the in-phase component and a second decorrelated signal associated with the quadrature phase component). The first decorrrelated signal and the second decorrelated signal can be combined to generate a decorrelated signal that is then used to determine the distance and / or velocity of the subject. Additionally, the processor can also estimate a frequency variation with time of the decorrelated signal. The frequency variation with time can provide additionally redundancy to the determination of the distance and / or velocity of the subject. For instance, to determine the distance and / or the velocity of the subject, the processor can mask the estimated frequency variation with time using the decorrelated signal. Masking the estimated frequency variation can place bounds on the distance of the subject. More specifically, masking the estimated frequency variation can provide a minimum possible distance of the subject and a maximum possible distance of the subject. Accordingly, the determined distance of the subject must be within the bounds (e.g., between the minimum possible distance and the maximum possible distance). Therefore, masking the estimated frequency variation provides redundancy to the determination of the distance and / or the velocity of the subject. This improves the resolution of the heart rate and / or respiration rate. FIG. 6 shows an example decorrelated signal 644 and the estimated frequency variation with time 646 of the decorrelated signal 644. The distance of the subject can be determined from the decorrelated signal 644. For example, in one instance, the distance of the subject can be determined based on the peak 644a of the decorrelated signal 644. In another instance, the distance of the subject can be determined based on the centroid of the decorrelated signal 644. The estimated frequency variation 646 can be masked with the decorrelated signal 644 to improve the determination of the distance of the subject. For instance, the points 646a and 646a’ on the estimated frequency variation 646, can provide bounds (e.g., maximum possible distance and minimum possible distance) on the distance of the subject. In this manner, the position of the subject can be determined using the decorrelated signal 644 and the estimated frequency variation with time. As will be readily understood, the velocity of the subject can be determined by analyzing the change in the distance of the subject over time. In some variations, the use of frequency modulated pulse can enable the velocity of the subject to be determined. For example, with frequency modulated pulse, the frequency would vary with time. As discussed above, the change of frequency with time is proportional to a change in the position of the subject. If the frequency is measured for a same relative point in time from the start of the transmission of a frequency modulated pulse radar signal and the frequency changes, then the rate of change of frequency with time can be used to determine how much the target has moved. The controller 104 may be configured to calculate the heart rate and the respiration rate based on the determined distance and / or velocity of the subject. In particular, the controller 104 (e.g., processor included in the controller 104) may be configured to determine the change in distance of the subject over time. The controller 104 may be configured to transform a signal representing the change in distance of the subject over time to a frequency domain. Put differently, the controller 104 can apply a Fast Fourier Transform on a signal that represents the change in distance of the subject over time. For example, FIG. 7A shows an example signal representing the change in distance of a subject over time. FIG. 7B shows the transformed signal in a frequency domain following the application of Fast Fourier Transform. The controller 104 may be configured to determine the heart rate and / or respiration rate of the subject based on the transformed signal in FIG. 7B. For example, the strongest periodic motion (e.g., peak 776a in FIG. 7B) in a given frequency range may be identified as representing the respiration rate. That is, the respiration rate of the subject can be detected by looking at the strongest periodic motion in a given frequency range. The weaker amplitude periodic motion (e.g., peak 776b in FIG. 7B) with a frequency which is typically equal or greater than the detected respiration rate may be identified as the heart rate. Put differently, the heart rate of the subject may be detected as the weaker amplitude periodic signal. In this manner, the system 100 can detect heart rate and / or respiration rate of one or more subjects. In variations in which the system 100 includes two or more receivers 108, the controller 104 can be configured to detect the heart rate and / or respiration rate based on the reflected portion of the signal received at each of the receiver 108. For example, if the system 100 includes two receivers 108, then the controller 104 can determine a first heart rate and / or a first respiration rate based on a reflected portion received at a first receiver. The controller 104 can determine a second heart rate and / or a second respiration rate based on a reflected portion received at a second receiver. The controller 104 can then detect the heart rate of the subject based on the first heart rate and the second heart rate (e.g., by taking an average of the first heart rate and second heart rate, by applying weights to the first heart rate and second heart rate, etc.). In a similar manner, the controller 104 can detect the respiration rate of the subject based on the first respiration rate and the second respiration rate (e.g., by taking an average of the first respiration rate and the second respiration rate, by applying weights to the first respiration rate and the second respiration rate, etc.). In some variations, the controller 104 can be configured to assign weights to the output from each of the receiver (e.g., assigning weights to the heart rate and respiration rate that are detected from a reflected portion received at each receiver). This can improve the accuracy and robustness of the system 100. In some variations, the use of two or more receivers can improve the signal-to-noise ratio. Furthermore, the use of two of more receivers enables redundancy in the detection of heart rate and / or respiration rate, thereby improving the resolution of the system 100. More importantly, the use of two or more receivers may enable the controller 104 to determine the three-dimensional position and motion of the subject. For example, the controller 104 can determine a three-dimensional position, velocity, and acceleration of the subject based on a corresponding reflected portion of the frequency modulated pulse radar signal received from each of the receivers. The controller 104 can then determine the respiration rate and the heart rate of the subject based on the determined three-dimensional position, velocity, and acceleration. For example, the patterns for the position, velocity, and acceleration of the heart and lung of a subject are different. These differences in pattern can be used to separate the motions of the lung and the heart. The difference in time can be used to measure the heart rate and lung rate accurately. FIG. 8A and FIG. 8B show example configurations for a transmitter 106 and multiple receivers 108 that can be included in the system 100. As discussed above, the transmitter 106 and the receiver 108 can be included within a same physical device. Alternatively, the transmitter 106 and the receiver 108 can be included in separate physical devices. As discussed above, the use of UWB frequency modulated pulse radar signals can enable the determination of heart rate and / or respiration rate of subject(s) that are positioned at a close distance to the system 100. For example, in variations in which the transmitter 106 and the receiver 108 are in the same physical device, the UWB frequency modulated pulse radar signals may enable determination of heart rate and / or respiration rate of subject(s) that are positioned as close a 0m from the physical device as long as there is no contact between the subject(s) and the physical device. In variations in which the transmitter 106 and the receiver 108 are not in the same physical device, the UWB frequency modulated pulse radar signals may enable determination of heart rate and / or respiration rate of subject(s) positioned as close as Om from the receivers 108 as long as the transmitter 106 and the receiver 108 do not impede each other’s view of the subject(s). Referring back to FIG. 1, in some variations, the controller 104 can be communicably coupled to one or more sensor(s) 110, including and not limited to, gyroscopes, accelerometers, etc. These sensors 110 can correct for a motion of the one or more devices that include the transmitter 106 and / or the receiver 108, thereby making the system 100 portable. More specifically, in scenarios in which the system 100 is operated as a hand held device, the sensor(s) 110 can compensate for a motion of the device. Similarly, in scenarios in which the system 100 is mounted on a moving platform, the sensor(s) can compensate for a motion of the platform. In variations in which the controller 104 is communicably coupled to the sensor(s) 110, the controller 104 can be configured to receive sensor data from the sensor(s) 110 and process the sensor data. The controller 104 can be configured to determine a distance and / or velocity of one or more subject based on the reflected portion of the transmitted pulse radar signal and based on the sensor data. In some variations, the controller 104 can be communicably coupled to a user interface 102. The user interface 102 may be rendered on any suitable computing device. Some non-limiting examples of computing device include computers (e.g., desktops, personal computers, laptops, etc.), tablets and e-readers (e.g., Apple iPad®, Samsung Galaxy® Tab, Microsoft Surface®, Amazon Kindle®, etc.), mobile devices and smart phones (e.g., Apple iPhone®, Samsung Galaxy®, Google Pixel®, etc.), etc. The computing device may be communicatively coupled to the controller 104 via a network (e.g., Internet, Local Area Network (LAN), Wider Area Network (WAN), and / or the like). The user interface 102 can be configured to display the heart rate and / or the respiration rate of the one or more subjects. In some variations, the controller 104 can be directly connected to the user interface 102 (e.g., the controller 104 and the user interface 102 can be on a same device). FIG. 9 is a flowchart showing an example method 900 for detecting heart rate and / or respiration rate of one or more subjects. At 992, the method 900 includes transmitting a frequency modulated pulse radar signal towards a subject. The frequency modulated pulse radar signal can be a UWB frequency modulated pulse radar signal. The method can further include generating the frequency modulated pulse radar signal on-the-fly and / or controlling the transmission of the frequency modulated pulse radar signal on-the-fly. For example, the method can include generate an in-phase (I) signal and a quadrature phase (Q) signal. The method can then include combining the in-phase signal and the quadrature phase signal to generate the frequency modulated pulse radar signal. In some variations, the method can include modifying the amplitude, duration, frequency, and / or a time delay of the frequency modulated pulse radar signal, so as to control the transmitted signal on-the-fly. At 994, the method can include receiving a reflected portion (e.g., reflected from the subject) of the transmitted signal (e.g., signal transmitted in step 992). The method can further include for a given timeframe, capturing the received signal and accumulating the received signal. In some variations, the method can also include capturing the in-phase component and the quadrature phase component of the received signal separately. Subsequently, accumulating the in-phase component and the quadrature phase component of the received signal separately. In some variations, the method can also include modifying a subsequent frequency modulated pulse radar signal that is to be transmitted towards the subject based on the received reflected signal. At 996, the method can include determining a position (e.g., distance) of the subject based on the received reflected portion of the transmitted signal. Additionally, the method can include determining a velocity of the subject. In some variations, the method can also include determining an acceleration of the subject. More specifically, the method can include decorrelating the reflected portion from the transmitted signal. The method can also include estimating a frequency variation with time of the decorrelated signal. The method can include determining the distance of the subject based on the decorrelated signal and the estimated frequency variation. At 998, the method can include determining the heart rate and / or respiration rate of the subject based on the determined distance and / or velocity of the subject. For example, the method can include determining a change in the distance of the subject overtime. The method can include applying Fast Fourier transform to the change in distance over time to produce a transformed signal. The method can include determining the heart rate and / or the respiration rate based on the transformed signal. For example, the method includes determining the respiration rate of the subject based on the strongest periodic motion in a given frequency range and determining the heart rate of the subject based on the weaker amplitude periodic motion with a frequency that is equal or greater than the detected respiration rate. While certain embodiments have been described, these embodiments have been presented by way of example only and are not intended to limit the scope of the invention. Indeed, the novel methods, devices and systems described herein may be 5 embodied in a variety of forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit and scope of the invention. Furthermore, it will be understood that features disclosed in relation to one embodiment can be combined with features disclosed in relation to another embodiment. The accompanying claims 10 and their equivalents are intended to cover such forms or modifications as would fall within the spirit and scope of the invention.

Claims

1. A system for measuring respiration rate and heart rate of a subject remotely, the system comprising:a transmitter configured to transmit an ultra-wide band frequency modulated pulse radar signal towards the subject;at least one receiver configured to receive a reflected portion of the ultra-wide band frequency modulated pulse radar signal; anda controller configured to:determine a position of the subject based at least in part on the reflected portion of the ultra-wide band frequency modulated pulse radar signal, and determine the respiration rate and / or the heart rate of the subject based on the determined position of the subject.

2. The system of claim 1, wherein the at least one receiver comprises a plurality of receivers, each receiver of the plurality of receivers being configured to receive a corresponding reflected portion of the ultra-wide band frequency modulated pulse radar signal.

3. The system of claim 2, wherein the controller is configured to: determine a three-dimensional position, velocity, and acceleration of the subject based at least in part on the corresponding reflected portion of the ultra-wide band frequency modulated pulse radar signal from each receiver of the plurality of receivers; anddetermine the respiration rate and the heart rate of the subject based on the determined three-dimensional position, velocity, and acceleration.

4. The system of claim 1, wherein the controller is further configured to: decorrelate the reflected portion of the ultra-wide band frequency modulated pulse radar signal from the transmitted signal to produce a decorrelated signal;estimate a frequency variation of the decorrelated signal with time; and determine the position of the subject based on the decorrelated signal and the estimated frequency variation.

5. The system of claim 4, wherein the controller is further configured to mask the estimated frequency variation using the decorrelated signal.

6. The system of claim 1, wherein the controller is configured to: determine a change in position of the subject over time; and apply Fast Fourier Transform on the change in position to determine the heart rate and the respiration rate of the subject.

7. The system of claim 1, wherein the controller is further configured to generate the ultra-wide band frequency modulated pulse radar signal.

8. The system of claim 7, wherein the controller is configured to modify the generated ultra-wide band frequency modulated pulse radar signal on-the-fly.

9. The system of claim 7, wherein the controller is configured to:generate an in-phase pulse;generate a quadrature phase pulse; andcombine the in-phase pulse and the quadrature phase pulse, thereby generating the ultra-wide band frequency modulated pulse radar signal.

10. The system of claim 1, wherein the transmitter is positioned in a first device and the at least one receiver is positioned in a second device different from the first device.

11. The system of claim 1, wherein the transmitter and the at least one receiver are positioned in a same device.

12. The system of claim 11, further comprising:at least one sensor to measure a change in motion of the device, and wherein the controller is configured to determine the position of the subject based on the reflected portion of the ultra-wide band frequency modulated pulse radar signal and the change in motion of the device.

13. The system of claim 12, wherein the at least one sensor includes at least one of a gyroscope and an accelerator.

14. The system of claim 12, wherein the device is a portable device.

15. The system of claim 1, wherein the system is configured to determine the heart rate and the respiration rate of a subject positioned between a distance of about 0.25m and about 10m from the system.5 16. A method, comprising:transmitting an ultra-wide band frequency modulated pulse radar signal towards a subject;receiving a reflected portion of the transmitted signal;determining, via a controller, a position of the subject based at least in part on 10 the reflected portion; anddetermining, via the controller, a respiration rate and heart rate of the subject based on the determined position.

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