Garmin Xero C1 Pro Developers Menu / Measuring Distanced Tracked

GunsNotPuns

GunsNotPuns

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I only learned of this just yesterday and it might be some use.

On your Xero C1 Pro, scroll down to Settings and go to "About". Hit OK five times and it will present you with developer's options. One of them is "Show Distance Tracked". Click OK on it to enable it.

The Xero C1 Pro seems to be measuring velocity between 20 and 30 metres. I had a low of about 19.7 metres and about 27 metres at its longest measurement distance.

It's display only -- you'll see the distance number beside the shot total -- and I couldn't figure out a way to have that number saved to the unit as another variable. At least, it didn't show up when I exported my data as CSV.

Now, I'll leave it to smarter people than I, but I do wonder if this can get someone part of the way of calculating BC based on this additional data.

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BC is a measurement of drag or deceleration. One would need two velocity points a known distance apart in order to calculate BC. The data you are getting from the Xero is one velocity point at one distance. You have precisely half the data needed to calculate drag.
 
prairie lover said:
I wonder if it then back calculates the shown speeds to the muzzle. Or is it 20m out?
Click to expand...

Thats an interesting question but to do that, the calculation would require the BC of the bullet in use.

The more important aspect is that with these kinds of chronographs, you will need to set your ballistic calculations so that the velocity matches the longer measurement distance.
 
todbartell said:
Garmin give you the muzzle velocity, I have run mine against the Labradar and the muzzle velocity are usually within 1 fps of each other
Click to expand...

How do you know the displayed velocity is at the muzzle? The system doesn't read the velocity at the muzzle and it doesn't know the BC of the bullet, thus it has no way of calculating the velocity at the muzzle. That it says "muzzle velocity" doesn't mean that is true. You are making a massive assumption somewhere.
 
Well on the Labradar it shows velocity at the muzzle (v0) and I set my v1 at 4 yards, which will always be slower than v0

The v0 of the Labradar and the Xero muzzle velocity are basically the same.

kdfQf7a.png


mACXDsO.jpg
 
The bottom pic shows the answer. The LabRadar displays two velocity points, at 4 and 75 (yards I assume). That allows the software to calculate velocity back to the muzzle.

That you can also show the Xero produces essentially the same velocity suggests the Xero is doing the same thing, just not displaying it.

Hard data is always better than guessing and supposition.
 
I Dont Care About You said:
How do you know the displayed velocity is at the muzzle? The system doesn't read the velocity at the muzzle and it doesn't know the BC of the bullet, thus it has no way of calculating the velocity at the muzzle. That it says "muzzle velocity" doesn't mean that is true. You are making a massive assumption somewhere.
Click to expand...
Labradar does some magic stuff to get the muzzle velocity. I read about it someplace but am not going to BS the crowd about it.
 
GunsNotPuns said:
I only learned of this just yesterday and it might be some use.

On your Xero C1 Pro, scroll down to Settings and go to "About". Hit OK five times and it will present you with developer's options. One of them is "Show Distance Tracked". Click OK on it to enable it.

The Xero C1 Pro seems to be measuring velocity between 20 and 30 metres. I had a low of about 19.7 metres and about 27 metres at its longest measurement distance.

It's display only -- you'll see the distance number beside the shot total -- and I couldn't figure out a way to have that number saved to the unit as another variable. At least, it didn't show up when I exported my data as CSV.

Now, I'll leave it to smarter people than I, but I do wonder if this can get someone part of the way of calculating BC based on this additional data.

View attachment 751585
Click to expand...
My new unit has firmware 3.32 and this hidden feature does not seem to be available.
 
These new chronographs use doppler radar as opposed to starting a "timer", like the old chronos used to; they had "start timer/stop timer" logic to them, effectively clocking the amount of time it took the projectile to travel a known distance between the sensors.

Doppler radar uses extremely high frequency radio pulses (24 billion pulses per second) which are constantly transmitting the moment the chrono is "armed" to start watching for reflected pulses. Some of these radio pulses bounce back off of the projectile that is travelling away from the firearm and the shift downward in frequency from the original outbound radio pulses (because the projectile is travelling away) allows the Garmin to calculate the velocity of the projectile once its received enough pulses back to make an accurate calculation.

Presumably this hidden distance value is the point at which it's determined that it's received enough pulses back to make the calculation.

The only way to determine the BC of a given bullet using the Garmin, or any other radar based chrono, would be to have one at the muzzle, and one (or more) at a known distance (or distances) downrange close enough to a target that the other chrono(s) could pick up the reflections from the projectile as it passed by.
 
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