Moving-entity detection

Abstract

Sensing moving entities includes transmitting a stepped-frequency radar signal including multiple frequencies through a wall from a first side of the wall to a second side of the wall. Portions of the radar signal that are reflected by entities located beyond the second side of the wall are detected. The reflected portions are processed to generate processed data including information associated with frequency shifts between the transmitted signal and the detected signal. The processed data is analyzed to determine if reflected portions are associated with moving entities.

1 . A method of sensing moving entities, the method comprising:
 transmitting a stepped-frequency radar signal including a plurality of frequencies, at least a portion of the transmitted radar signal moving through a wall from a first side of the wall to a second side of the wall;   receiving reflected portions of the radar signal with a first antenna arranged to receive reflected radar signals at a first location and a second antenna arranged to receive reflected radar signals at a second location;   processing the reflected portions received from the first and second antennas to generate processed data including information associated with frequency shifts between the transmitted signal and the reflected portions of the radar signal received at the first location and information associated with frequency shifts between the transmitted signal and the reflected portions of the radar signal received at the second location; and   analyzing the processed data to determine if reflected portions of the radar signal are associated with moving entities located beyond the second side of the wall.   
     
     
         2 . The method of  claim 1 , wherein analyzing the processed data includes calibrating the processed data. 
     
     
         3 . The method of  claim 2 , wherein calibrating the processed data includes compensating for reflections near the first or second antennas. 
     
     
         4 . The method of  claim 2 , wherein calibrating the processed data includes compensating for reflections behind the first or second antennas. 
     
     
         5 . The method of  claim 2 , wherein the processed data is calibrated for each separate attempt to sense moving entities. 
     
     
         6 . The method of  claim 1 , wherein analyzing the processed data includes removing information associated with reflections from stationary objects. 
     
     
         7 . The method of  claim 1 , wherein analyzing the processed data includes removing information associated with reflections from objects within a proximity to the first or second antennas. 
     
     
         8 . The method of  claim 1 , wherein analyzing the processed data includes performing a Fourier transform on information associated with the processed data, the method further comprising detecting degraded performance based on whether results of the Fourier transform meet a characteristic. 
     
     
         9 . The method of  claim 1 , wherein analyzing the processed data includes performing a first Fourier transform with a first integration time and a second Fourier transform with a second integration time longer than the first integration time on the same information associated with the processed data. 
     
     
         10 . The method of  claim 9 , further comprising detecting degraded performance based on whether results of the first Fourier transform meet a first characteristic and results of the second Fourier transform meet a second characteristic different from the first characteristic. 
     
     
         11 . The method of  claim 1 , wherein analyzing the processed data includes analyzing frequency and phase shifts between the transmitted signal and the detected signal to determine movement of objects at a distance. 
     
     
         12 . The method of  claim 1  wherein the transmitting, receiving and processing is performed by a portable device. 
     
     
         13 . The method of  claim 1  wherein the portable device comprises a handheld device. 
     
     
         14 . The method of  claim 1  wherein receiving reflected portions of the radar signal with the first antenna and the second antenna includes receiving reflected portions of the radar signal with a first antenna located on a first half of a device and a second antenna located on a second half of the device, where the first half of the device is closer to the first side of the wall than the second half of the device. 
     
     
         15 . The method of  claim 1  wherein receiving reflected portions of the radar signal with the first antenna and the second antenna includes receiving reflected portions of the radar signal with a first antenna located on a half of a device and a second antenna located on the other half of the device. 
     
     
         16 . A system for sensing moving entities, the system comprising:
 a stepped-frequency radar transmitter configured to transmit a stepped-frequency radar signal;   a first antenna arranged to receive reflected radar signals at a first location;   a second antenna arranged to receive reflected radar signals at a second location; and   a processor configured to:
 process the reflected portions received from the first and second antennas to generate processed data including information associated with frequency shifts between the transmitted signal and the reflected portions of the radar signal received at the first location and information associated with frequency shifts between the transmitted signal and the reflected portions of the radar signal received at the second location, and 
 analyze the processed data to determine if reflected portions of the radar signal are associated with moving entities located beyond a far side of a wall. 
   
     
     
         17 . The system of  claim 16  further comprising a demodulator which receives both the stepped-frequency radar signal and a reflected portion of the radar signal, wherein the demodulator outputs in phase and out of phase data. 
     
     
         18 . The system of  claim 16 , wherein the system is configured to be operable using AA batteries. 
     
     
         19 . The system of  claim 16 , wherein the processor is configured to remove information associated with signal reflection from stationary objects. 
     
     
         20 . The system of  claim 16 , wherein the processor is configured to remove information associated with signals reflected from objects within a proximity to the first or second antennas. 
     
     
         21 . The system of  claim 16 , wherein the processor is configured to perform a first Fourier transform with a first integration time and a second Fourier transform with a second integration time longer than the first integration time on the same information associated with the processed data. 
     
     
         22 . The system of  claim 16 , wherein the processor is configured to calibrate or process reflected portions of the radar signal based on which of the first and second antennas receives the reflected portion of the radar signal. 
     
     
         23 . The system of  claim 16  wherein the system comprises a portable device. 
     
     
         24 . The system of  claim 23  wherein the portable device comprises a handheld device. 
     
     
         25 . The system of  claim 16  wherein the first antenna is located on a first half of a device and a second antenna is located on a second half of the device, where the first half of the device is closer to the first side of the wall than the second half of the device. 
     
     
         26 . The system of  claim 16  wherein the first antenna is located on a half of a device and a second antenna is located on the other half of the device.