xband presence detector behavior
jcuesta
Posts: 1
Hi all,
I have mounted a set of Xband motion detectors and I'm testing how they work. (just in case: http://www.parallax.com/Store/Sensors/ObjectDetection/tabid/176/ProductID/606/List/0/Default.aspx?SortField=ProductName,ProductName)
I'm not interested in checking the speed of the moving object or the "amount" of movement detected, I'm only interested in knowing if there si movement or not in the area.
What I did for detecting that was to set hardware sensibility to maximum (maximum range), then listen to the sensor output for a given amount of time (2 seconds), then count the number of flanks it sent back and then compare it with a threshold (in this case 5).
that configuration worked fine for 15 different sensors when tested in lab but it is not working that fine when we moved the sensors outdoors.
current installation is made with 12 different motes that send their detection data via RF to a gateway, the gateway then sends the data to a data base where I'm able to check it. Current deployment allow me to programm the motes so I can test with different listening times/thresholds if needed.
Motes are located at 4 meters high aiming to the ground at a 14 metter distance, that means that the "chest" of people walking in the area should be in the maximum radiation angle of the radar when at about 9-11 meters of the radar in straigh line (which should fall into the maximum detection range of 15 m as stated by the data sheet).
What i found is that radars sensibility is quite variable, some sensors do fine while others send huge amount of false positive detections.
- Do you think that my listening times/thresholds are ok or based on your knowledge on the sensors behavior you think that i should change them?
- Radars are spaced about 70-100 meters from each other, do they might be interefring each other detection patterns?
- Some radars are placed just behind another radar (back to back). Do they might be interering each other signal?
- Do you consider that my differences in sensor behavior (some working fine while others sending lots of false positives) is normal? How can i solve it? I'm working on the calibration of each sensor in a one by one basis, modifiying the listening and threshold of each of it. but that brings me back to 1st question. ¿any better idea?.
Thanks.
Javier.
I have mounted a set of Xband motion detectors and I'm testing how they work. (just in case: http://www.parallax.com/Store/Sensors/ObjectDetection/tabid/176/ProductID/606/List/0/Default.aspx?SortField=ProductName,ProductName)
I'm not interested in checking the speed of the moving object or the "amount" of movement detected, I'm only interested in knowing if there si movement or not in the area.
What I did for detecting that was to set hardware sensibility to maximum (maximum range), then listen to the sensor output for a given amount of time (2 seconds), then count the number of flanks it sent back and then compare it with a threshold (in this case 5).
that configuration worked fine for 15 different sensors when tested in lab but it is not working that fine when we moved the sensors outdoors.
current installation is made with 12 different motes that send their detection data via RF to a gateway, the gateway then sends the data to a data base where I'm able to check it. Current deployment allow me to programm the motes so I can test with different listening times/thresholds if needed.
Motes are located at 4 meters high aiming to the ground at a 14 metter distance, that means that the "chest" of people walking in the area should be in the maximum radiation angle of the radar when at about 9-11 meters of the radar in straigh line (which should fall into the maximum detection range of 15 m as stated by the data sheet).
What i found is that radars sensibility is quite variable, some sensors do fine while others send huge amount of false positive detections.
- Do you think that my listening times/thresholds are ok or based on your knowledge on the sensors behavior you think that i should change them?
- Radars are spaced about 70-100 meters from each other, do they might be interefring each other detection patterns?
- Some radars are placed just behind another radar (back to back). Do they might be interering each other signal?
- Do you consider that my differences in sensor behavior (some working fine while others sending lots of false positives) is normal? How can i solve it? I'm working on the calibration of each sensor in a one by one basis, modifiying the listening and threshold of each of it. but that brings me back to 1st question. ¿any better idea?.
Thanks.
Javier.