Systems and methods for high resolution distance sensing and applications
A sensing system includes a first radar sensing assembly and an analysis system. The first radar sensing assembly measures plural distances to a first target location at different times using radar. The analysis system receives the plural distances from the first radar sensing assembly and quantifies movements of a target object at the first target location at the different times by calculating differences in the plural distances measured by the first radar sensing assembly. The analysis system generates one or more first quantified activity level values indicative of the movements of the target object at the first target location using the differences in the plural distances that are calculated.
1 . A system, comprising:
a server;
an area having an animate object present therein;
a camera that observes the area and is communicatively coupled to the server; and
a distance sensor positioned to observe the area and is communicatively coupled to the server, wherein (i) the distance sensor senses the animate object in the area, generates a reading based on sensing the animate object in the area, and sends the reading to the server, (ii) the camera captures an image depicting the object in the area and sends the image to the server, and (iii) the server receives the reading and the image, determines whether the animate object is a human being based on the reading and the image, and takes an action based on the animate object being the human being.
2 . The system of claim 1 , wherein the distance sensor comprises a radar sensing assembly that transmits an electromagnetic pulse sequence toward the area, receive an echo of the electromagnetic pulse sequence reflected off the animate object, determine a time of flight based on correlating the echo to the electromagnetic pulse sequence, and generate the reading as a separation distance based on the time of flight.
3 . The system of claim 2 , wherein the radar sensing assembly comprises a direct-sequence spread-spectrum radar device configured to directly modulate a carrier signal using a digital pulse sequence.
4 . The system of claim 2 , wherein the radar sensing assembly determines the time of flight by comparing a correlation window corresponding to a receive pattern to a plurality of subsets of a digitized echo signal, identifying a correlation value of interest, and identifying a subset of interest corresponding to the correlation value of interest.
5 . The system of claim 4 , wherein the radar sensing assembly determines the time of flight using (i) a coarse stage that determines a time delay of interest based on correlating the echo and (ii) a fine stage that compares the digitized echo signal to a replicated copy of the electromagnetic pulse sequence that is delayed by the time delay of interest to refine the time of flight.
6 . The system of claim 2 , wherein the radar sensing assembly comprises a digital output gate disposed between a transmit pattern generator and a mixer, wherein the digital output gate enters a tri-state mode to reduce a transmit signal leakage during switching from a transmit mode to a receive mode.
7 . The system of claim 2 , wherein the radar sensing assembly measures the separation distance with an accuracy of 1 millimeter or less and at a rate comprising 1000 measurements per second.
8 . The system of claim 2 , wherein the radar sensing assembly is disposed behind a covering structure that conceals the radar sensing assembly from view while permitting transmission of the electromagnetic pulse sequence through the covering structure toward the area.
9 . The system of claim 1 , further comprising:
an optical sensing system comprising a light source that generates a light toward a target location on the human being and an optical receiver that detects a reflection of the light off the target location, wherein the server determines an oxygenation level of blood of the human being by correcting a quantified amount of the reflection using the readings.
10 . The system of claim 1 , wherein the server generates a breathing pattern signal by filtering a time series of the reading to isolate a respiration-indicative change in the reading, and generate a cardiac signal by applying a wavelet transform to at least one of (i) the time series or (ii) a remainder signal produced by removing the breathing pattern signal from the time series.
11 . The system of claim 1 , wherein the server fuses the distance reading and the image to perform a calculation of a plurality of 3 D parameters of the human being.