Labradar velocity question.

[jmikell870]

Does anyone know how far from there muzzle a LabRadar measures velocity?
In most other chronograph systems, this is easy to determine. A MagnetoSpeed reads at the bayonet, optical systems measure between the optical sensors.
However, it’s a little different in a LabRadar. A LabRadar must first be triggered while being mounted offset (hopefully) from the direct path of the bullet. The bullet must then travel from the muzzle and penetrate the sensor’s cone shaped Doppler area.
Further complicating this inquiry is the varying distance of offset. The LabRadar allows users to select 6, 12 or 24” off offset. Does this change where the unit is triggered and measures? If so, how much?

 

[6.5SH]

It calculates it back to the muzzle. The purpose of the offset is to tell the unit where to 'expect' your projectiles are coming from and ignore strays. If you use the app it will actually show you exactly how far away you are from the unit after it detects a shot. Example you set 12" but were a little wider it will show 12.567" etc.

 

[jmikell870]

How does it I calculate back to the muzzle of the unit doesn’t know factors like bc?
I did not know about the app calculating offset. That’s really interesting. I’m going to try it out next time. Thanks. Very helpful.

 

[6.5SH]

Triangulation would be my best guess, it knows where it is and how wide the beam is and your entry angle from the offset. If you are using trigger mode it knows when the shot "started" as well. The unit can also measure distance from projectile reflections.
If you open up the "Shot00xx Track.csv" files you will see the distance down to the hundredth of a yard, time and SNR for as far as it can track the shot. The 5 distances you choose on the unit or the app are just what it can display.

Series No	7​
Shot No	21​
Time (s)	Vel (fps)	Dist (yd)	SNR
0​	2430.17​	0​	-
0.021021​	2398.43​	16.87​	25.17​
0.022021​	2403.04​	17.67​	22.72​
0.023021​	2393.05​	18.47​	28.03​
0.024021​	2397.22​	19.26​	24.04​
0.025021​	2396.87​	20.06​	22.61​
0.026021​	2394.46​	20.86​	20.93​
0.027021​	2393.89​	21.66​	21.79​
0.028021​	2390.14​	22.46​	21.85​
0.029021​	2390.05​	23.25​	22.73​
0.030021​	2389.76​	24.05​	24.03​
0.031021​	2387.36​	24.85​	24.18​
0.032021​	2383.6​	25.64​	19.61​
0.033021​	2383.75​	26.44​	16.04​
0.034021​	2386.27​	27.23​	14.82​
0.035021​	2385.22​	28.03​	11​

 

[jmikell870]

I guess Bc would be irrelevant at the short distances we are talking about.