Patent Application
20230350047
The present invention relates generally to the monitoring of the physiological movement of subjects. More particularly, the present invention relates to devices and methods using FMCW radar and software algorithms to monitor vital signs of subjects.
“RADAR” stands for Radio Detection and Ranging, meaning that it is capable of detecting objects and also evaluating object parameters. Radar systems have long been employed for determining the distance between a target and the radar system. The distance is directly related to a transmission of a frequency modulated signal and a received reflected frequency modulated signal. The distance is calculated by taking the time delay or frequency difference between the transmitted and received signals. Radar systems use transceivers, which can include a radio frequency antenna for transmitting and a separate receiver antenna for receiving the reflected signal.
Traditionally, the presence and motion of objects were detected using continuous wave (CW) Doppler radar. The CW Doppler radar is a simple and efficient solution only when detection of a moving object is the only outstanding task to be completed. CW Doppler radar uses the Doppler effect, which concerns all sorts of wave generators and states the following:
Wave fronts, transmitted by a wave generator (e.g. sound, microwaves, light, etc.) hit a moving target. Depending on the direction of the motion of the object, the wave fronts are either “compressed” or “diluted”, which means a shift in frequency. The signal, shifted in frequency and reflected, is subtracted from the unchanged transmit signal in a relatively simple mixer (called “homodyne” mixing) and results in a sinusoidal intermediate frequency (IF). It is irrelevant whether the sensor moves relatively to the object or the object moves relatively to the sensor. Only the component of the velocity vector pointing parallel to the direct connection sensor-object can be calculated. The speed of an object can be evaluated by measuring the Doppler frequency, while considering the angle of the motion vector. Measuring the Doppler frequency is done by counting the zero crossings in an analog system or using fast Fourier Transforms (FFT) in a digital system.
A traditional method to measure position and distance (range) of an object involves using frequency modulated continuous wave (FMCW) “pulse” radar. A time delay is generated and measured by transmitting a short pulse and clocking the reception of the reflected pulse. Since the transmitted pulse and reflected pulse travel at the speed of light, a pulse would be delayed by six nanoseconds for an example object distance of one meter. There are significant issues with using pulse radar. For example, in order to obtain good resolution for an object at a close distance away, the pulses must be very short. Short pulses require enormous bandwidth, which may not be allowed by certification and regulation authorities such as the Federal Aviation Administration (FAA). In general, pulse radar is primarily used to evaluate the distance and range of objects. Velocity information can only be obtained by a timely derivation (ds/dt) of distance over time taken from a plurality of measured distance values.
When a bacterial or viral infection is present, human and non-human animal (e.g. cattle) subjects have symptoms such as elevated heart rate and elevated respiration. Medical professionals are often notified of an infection only after a fever or other discomfort has developed at an aggravated state of the infection. There is a need in the field for a system and method to continuously monitor and store a history of vital signs of a subject prior to an infection reaching an aggravated state, thereby enabling a determination of how the infection initially occurred.
Systems and methods for monitoring vital signs (e.g. heartbeat, respiration) using FMCW millimeter wave radar are disclosed herein. A transceiver is used to transmit a first signal (FMCW) and receive a second signal (reflected). The transceiver transmits the second signal data to a computing device. A first set of radar data is generated by software on the computing device, based on the received second signal. A first set of Doppler interval measurements is obtained from the first set of radar data. A high Doppler response is obtained from the first set of Doppler interval measurements and vital sign data is extracted from the high Doppler response.
There are several advantages of the present invention, including the use of Doppler frequencies which are free to use according to FAA specifications. The operating frequencies are very high and living organisms (subjects) are not affected by the radiation or the transmission path. The FMCW radar system and method enables a subject to be remotely monitored without requiring physical access to the subject. Wireless transmission is utilized to transmit signal data from a transceiver to a computing device with software installed.
These and other features and advantages will be apparent from reading of the following detailed description and review of the associated drawings. It is to be understood that both the forgoing general description and the following detailed description are explanatory and do not restrict aspects as claimed.
The following descriptions relate principally to preferred embodiments while a few alternative embodiments may also be referenced on occasion, although it should be understood that many other alternative embodiments would also fall within the scope of the invention. The embodiments disclosed are not to be construed as describing limits to the invention, whereas the broader scope of the invention should instead be considered with reference to the claims, which may be now appended or may later be added or amended in this or related applications. Unless indicated otherwise, it is to be understood that terms used in these descriptions generally have the same meanings as those that would be understood by persons of ordinary skill in the art. It should also be understood that terms used are generally intended to have the ordinary meanings that would be understood within the context of the related art, and they generally should not be restricted to formal or ideal definitions, conceptually encompassing equivalents, unless and only to the extent that a particular context clearly requires otherwise.
For purposes of these descriptions, a few wording simplifications should also be understood as universal, except to the extent otherwise clarified in a particular context either in the specification or in particular claims. The use of the term “or” should be understood as referring to alternatives, although it is generally used to mean “and/or” unless explicitly indicated to refer to alternatives only, or unless the alternatives are inherently mutually exclusive. Furthermore, unless explicitly dictated by the language, the term “and” may be interpreted as “or” in some instances. When referencing values, the term “about” may be used to indicate an approximate value, generally one that could be read as being that value plus or minus half of the value. “A” or “an” and the like may mean one or more, unless clearly indicated otherwise. Such “one or more” meanings are most especially intended when references are made in conjunction with open-ended words such as “having,” “comprising” or “including.” Likewise, “another” object may mean at least a second object or more. Thus, in the context of this specification, the term “comprising” is used in an inclusive sense and thus should be understood as meaning “including, but not limited to.” As used herein, the use of “may” or “may be” indicates that a modified term is appropriate, capable, or suitable for an indicated capacity, function, or usage, while considering that in some circumstances the modified term may sometimes not be appropriate, capable, or suitable. A “computing device” can be a desktop, laptop, tablet, phone, and the like.
The disclosed FMCW radar systems and methods can be used for detecting and evaluating motion of objects (e.g. human or animal subjects, vehicles, machines). In a case of a stationary object, FMCW radar can define the object's instantaneous position (range, angle). In a case of a moving object, FMCW radar can measure the object's movement (velocity, direction) and clock and track the continuously changing position. FMCW radar uses high frequency electromagnetic (EM) waves to provide sufficient resolution and to accurately evaluate objects.
If using a 24 GHz FMCW radar transceiver, the RF signal bandwidth is 250 MHz and frequency deviation is allowed. Simple processing enables the transceiver and the subject to be as close as two or three meters apart (minimal distance). In order to have the transceiver closer to the subject, complex and fast digital signal processing (DSP) is required. At this lower distance to the subject, only one object can be detected. However, the present invention FMCW radar has a large zone of unambiguity, since the sawtooth repetition time can be selected as high as required.
This is a Divisional Application which claims priority to Nonprovisional Utility U.S. patent application Ser. No. 17/010,116 under 37 CFR 1.53(b).
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17010116 | Sep 2020 | US |
| Child | 18220242 | US |
