MS20 Sensitivity

ArkansasElkHunter

Well-known member
Joined
Jan 19, 2002
Messages
1,748
Reaction score
0
I did some testing today with the sensitivity of the ms20 sensor.  I wanted to see if you could vary the range and sensitivity by varying the distance from the sensor to the fresnal lens.  With the sensor in the original housing I was getting just over 70 feet max but only at about  +/-10° from center. The field of view got wider as you got closer to the sensor.  At 30 feet I was getting +/-50° from center.  I tried several different hole configurations and settled on a 1” square.  I will post those results.  I liked the square better than the circle because I got better triggers at ground level at the extreme outside angles.  It also limited the sensor field of view to about 60°.  The lens was mounted flat.   The sensor was 4’ off the ground.    You can set the sensor off by moving rapidly easier than when you move slower, so these results are based on a very slow walk almost trying to sneak past it.  The distances are from the board face to the fresnal lens not the sensor face.  The sensor sticks out past the board by 0.2”

0.75” –  at the distance the sensor would reliably pick up movement any where within an arc of 25’ form the sensor at +/- 35° from center.  At 30 feet it would still pick up but if you moved slow enough you could sneak by.  Not recommended

1.0”  -  at the distance the sensor would reliably pick up movement any where within an arc of 30’ form the sensor at +/- 30° from center.  At 40 feet it would still pick up but if you moved slow enough you could sneak by.  It would still pick up rapid movement out to about 50”.  Very good sensitivity within 30’, will pick up hand movement.   Would make a good shorter range setting.

1.25”  -  at the distance the sensor would reliably pick up movement any where within an arc of 40’ form the sensor at +/- 25°  (+/- 30° at 30’) from center.  At 50 feet it would still pick up but if you moved slow enough you could sneak by for a few steps.  It could be set off out to 65 feet in the center with a brisk walk.   At this distance it was the most sensitive to movement.  My cat was setting it off at 30 feet.  

1.5”  -  At this distance the sensor was beginning to drop off again.  Results were between the 1” and 1.25” results.    

The sun was bright today so I repeated these results after dark to ensure that the results were repeatable and they were.  I will probably settle on about 1.125”.  That should give great results out to 35 to 40 feet but begin dropping out by 50 feet or so.   When I mount my sensor I am going to cut the mounting blocks to the 1” setting and add a 1/8 shim.  Then I will be able to adjust the sensitivity if I need to.  Hope these results are helpful.
 



ArkansasElkHunter

Well-known member
Joined
Jan 19, 2002
Messages
1,748
Reaction score
0
Two blocks of UHMW (nylon) 1/2 inch thick the length of the sensor board.  I will mill slots (you could use a saw) at 1 inch from the back the length of the block about 1/8 inch deep.  Drill two pilot holes on the bottom and clearance holes to match through the housing.  Run some sheel metal screws into the blocks from outside the housing.  Now you should have two blocks standing up, mounted to the housing about 2.25" apart with the two slots facing each other.  Now just slide the sensor into place.

Now just loosen the screws up some, slide in some shims and retighten.  probably need to remove the board for shimming.  Leave the slots a little tight and it should hold the sensor in place.
 

ArkansasElkHunter

Well-known member
Joined
Jan 19, 2002
Messages
1,748
Reaction score
0
ment to add.   My timer boards will be 2.5 inches wide as well.  I am going to add another step above the PIR and slide them in on top
 

dharter

Well-known member
Joined
Jul 7, 2001
Messages
83
Reaction score
0
Last weekend I put out a camera with an MS-20.  I have the MS20 mounted in the original housing on the outside of the camera.  I also block off the sides of the fresnel lens.  I have a camera that has no delay so I just want to take pictures directily in front of the camera.  With that setup I measured the maximum range of the sensor as about 50 ft.  The temperature was about 60 degrees outside.
 


Top Bottom