31-05-2012, 03:59 PM
UWB RADARS
[attachment=23729]
Radar:
Radar (Radio Detection and Ranging) is basically a means of gathering information about distant objects or targets by sending electromagnetic waves to them and analyzing reflected waves or echo signals. Radar reflectivity is related to precipitation rate, total amount of precipitation falling on region over a fixed period of time can be determined by analyzing the reflectivity field. The targets to radar in this aspects or mainly raindrops however, various objects on ground varying from huge buildings to small air born insects also influence this criterion various calamities and extreme conditions like tornadoes, hurricanes, flash floods, snow storms can be predicted remarkably well by the radar and the following paper makes the brief yet effective contribution over this issue.
UWB Radar:
The detection of humans hidden by walls or rubble, trapped in buildings on fire or avalanche victims are of interest for rescue, surveillance and security operations. The problem of rescuing people from beneath the collapsed buildings does not have an ultimate technical solution that would guarantee efficient detection and localization of victims. The main techniques used are: Cameras with long optical fibers that are injected into the holes or fissures in the collapsed buildings (the usability of such devices and their efficiency depend on the structure of collapsed building and besides, when the victim is detected it is difficult in the most cases to determine its actual position). Sledge hammers are used to give a signal to potential victims, and rescuers with microphones are waiting for hearing the response (obvious limitation of this method is that unconscious people cannot be detected. Localization of victims is a problem as well). Search dogs are deployed in the disaster area. They detect presence of victims efficiently by smell, but information about their actual positions or quantity cannot be indicated. Moreover, dog is likely to indicate the presence of dead person which distracts rescuers from locations where living people can still be found . Due to the ability of electromagnetic waves to penetrate through typical building materials and its significant (in order of centimeters) spatial resolution, UWB radar is considered as preferred tool for detection and localization of people. Detection of human beings with radars is based on movement detection – respiratory motions and movement of body parts. These motions cause changes in frequency, phase, amplitude and periodic differences in time-of-arrival of scattered pulses from the target, which are result of periodic movements of the chest area of the target.
The primary hardware used for this study in PulsON 220 developed by Time Domain Corporation. The focus of this project is on detection techniques for a motionless human target using PulsON 220 UWB radar in mono static mode. The advantages of the PulsON 220 technology can be listed as:
1. Extremely low power
2. Spectral efficiency
3. Immunity to interference
4. Excellent wall penetration characteristics
Detection of human target through wall is of interest for many applications. Military industry could use it for hostage rescue situations. In such scenarios, detection and location of humans inside a room is very critical as unknown building layout together with presence of armed persons can be dangerous for the rescuers. Another use could be for disaster search and rescue operations such as people trapped under building debris during earthquake, explosion or fire. Ultra Wide Band (UWB) technology has emerged as one of the preferred choices for such applications due to its good range resolution and good penetration through most of the building materials. High range resolution is a result of high bandwidth of UWB radar and it helps in better separation of multiple targets. Detection of human target is based on the fact that there is always some movement due to breathing or movement of body parts (as in case of a walking person). This small movement can be used to detect a human being from other objects behind a wall or beneath rubble but it becomes challenging due to high clutter from the wall and other objects inside a room. The focus of this article is on detection techniques for a motionless human target using a mono static UWB radar.
UWB principles of operation and results:
Range from the sensor to a subject may be determined by measuring the time-of-flight of an UWB pulse (Kissick,2001). A typical impulse UWB radar implementation for looking through walls uses a pulse at a repetition frequency of some MHz over a bandwidth of 500 MHz-3 GHz. Every object in the field of view reflects energy back to the sensor. The signal returned from objects in the room is sampled at different range gates and the information from several receivers is coherently processed (phase synchronised) to give angle of arrival information. The available gain depends on the bandwidth of the returned signal. Angular position may be determined by an array radar of spaced-apart elements combining to form a beam or compared to measure phase differences. Figure 3 shows the hardware architecture of a typical UWB transmit and receive chain. However, this basic radar response typically gives too much clutter to make any decisions without a highly trained user, as all reflective parts of the area of interest are captured in every scan, not just people or moving objects. To mitigate this, layers of digital signal processing can be built onto the raw radar data to remix the signal, filter, track and classify potential targets and present targets to the user. Successful classification can improve efficiency of the tracker, maximising the use of processor time.
[attachment=23729]
Radar:
Radar (Radio Detection and Ranging) is basically a means of gathering information about distant objects or targets by sending electromagnetic waves to them and analyzing reflected waves or echo signals. Radar reflectivity is related to precipitation rate, total amount of precipitation falling on region over a fixed period of time can be determined by analyzing the reflectivity field. The targets to radar in this aspects or mainly raindrops however, various objects on ground varying from huge buildings to small air born insects also influence this criterion various calamities and extreme conditions like tornadoes, hurricanes, flash floods, snow storms can be predicted remarkably well by the radar and the following paper makes the brief yet effective contribution over this issue.
UWB Radar:
The detection of humans hidden by walls or rubble, trapped in buildings on fire or avalanche victims are of interest for rescue, surveillance and security operations. The problem of rescuing people from beneath the collapsed buildings does not have an ultimate technical solution that would guarantee efficient detection and localization of victims. The main techniques used are: Cameras with long optical fibers that are injected into the holes or fissures in the collapsed buildings (the usability of such devices and their efficiency depend on the structure of collapsed building and besides, when the victim is detected it is difficult in the most cases to determine its actual position). Sledge hammers are used to give a signal to potential victims, and rescuers with microphones are waiting for hearing the response (obvious limitation of this method is that unconscious people cannot be detected. Localization of victims is a problem as well). Search dogs are deployed in the disaster area. They detect presence of victims efficiently by smell, but information about their actual positions or quantity cannot be indicated. Moreover, dog is likely to indicate the presence of dead person which distracts rescuers from locations where living people can still be found . Due to the ability of electromagnetic waves to penetrate through typical building materials and its significant (in order of centimeters) spatial resolution, UWB radar is considered as preferred tool for detection and localization of people. Detection of human beings with radars is based on movement detection – respiratory motions and movement of body parts. These motions cause changes in frequency, phase, amplitude and periodic differences in time-of-arrival of scattered pulses from the target, which are result of periodic movements of the chest area of the target.
The primary hardware used for this study in PulsON 220 developed by Time Domain Corporation. The focus of this project is on detection techniques for a motionless human target using PulsON 220 UWB radar in mono static mode. The advantages of the PulsON 220 technology can be listed as:
1. Extremely low power
2. Spectral efficiency
3. Immunity to interference
4. Excellent wall penetration characteristics
Detection of human target through wall is of interest for many applications. Military industry could use it for hostage rescue situations. In such scenarios, detection and location of humans inside a room is very critical as unknown building layout together with presence of armed persons can be dangerous for the rescuers. Another use could be for disaster search and rescue operations such as people trapped under building debris during earthquake, explosion or fire. Ultra Wide Band (UWB) technology has emerged as one of the preferred choices for such applications due to its good range resolution and good penetration through most of the building materials. High range resolution is a result of high bandwidth of UWB radar and it helps in better separation of multiple targets. Detection of human target is based on the fact that there is always some movement due to breathing or movement of body parts (as in case of a walking person). This small movement can be used to detect a human being from other objects behind a wall or beneath rubble but it becomes challenging due to high clutter from the wall and other objects inside a room. The focus of this article is on detection techniques for a motionless human target using a mono static UWB radar.
UWB principles of operation and results:
Range from the sensor to a subject may be determined by measuring the time-of-flight of an UWB pulse (Kissick,2001). A typical impulse UWB radar implementation for looking through walls uses a pulse at a repetition frequency of some MHz over a bandwidth of 500 MHz-3 GHz. Every object in the field of view reflects energy back to the sensor. The signal returned from objects in the room is sampled at different range gates and the information from several receivers is coherently processed (phase synchronised) to give angle of arrival information. The available gain depends on the bandwidth of the returned signal. Angular position may be determined by an array radar of spaced-apart elements combining to form a beam or compared to measure phase differences. Figure 3 shows the hardware architecture of a typical UWB transmit and receive chain. However, this basic radar response typically gives too much clutter to make any decisions without a highly trained user, as all reflective parts of the area of interest are captured in every scan, not just people or moving objects. To mitigate this, layers of digital signal processing can be built onto the raw radar data to remix the signal, filter, track and classify potential targets and present targets to the user. Successful classification can improve efficiency of the tracker, maximising the use of processor time.