How do FX chrono's work?

[zephyr]

For a simple person like me, many things make me ponder. The latest is 'How do FX chrono's work?' and 'Where is the pellet speed measured in relation to the chrono?'.

I know how the Combro/Skan/Caldwell types work, and it's obvious where the speed is taken, but (for me) not the FX type. Does anyone know and willing to educate me, thanks.

[angrybear]

I believe it's like radar/sonar,
it shoots out timed signals that get a return from the projectile & the return delays tell it the velocity.

[ballisticboy]

Like all radar chronos, the signal is bounced off the pellet back to the chrono and the change in the frequency, due to the speed of the pellet, of the bounced back signal is used to calculate the speed. This is done from the time the pellet comes into the radar signal at different times as the pellet moves away to give a series for speeds at different times. The radar then uses the measured speeds to calculate the speed the pellet would have had at the radar, not at the muzzle of the gun. The radar cannot directly measure the muzzle velocity.

The problem is that the first measurements often have large errors, and there may not be many measurements for the radar to use to get a good estimate of the starting speed. You also have no idea how the radar has used its data to make the calculation.

[Neil54]

Doppler radar.
A radio beam comes out of radar unit, bounces off the pellet. The change in frequency is calculated, that of the radar beam - the speed of the pellet = change in received frequency.

Same as a motorbike coming towards you, the pitch increases and then decreases as it goes away.

Named after some bloke called Christian Doppler.

[Inspector 71]

Google Doppler shift and beat frequency.

[Jesim1]

Lots of answers above on the technical side, the main thing is that they work, and do a pretty good job overall when you look at how easy they are to use, and the type and quality of information you get back, like being able to email yourself the shot string, or see graphs on your phone. They tend to under read very slightly compared to other chrono's as they do take the pellets speed around 1 to 3 feet from the muzzel, but you can adjust this simply in the software and add say 1% to it's reading to nullify this.

For most people in general use they are great, but if your doing tuning work say as a regular thing and need the reading to be more accurate, then I'd get something else, but I'm happy with mine

[Shed tuner]

i love mine as it just sits there recording stuff whilst I;m shooting, not getting in the way, or influencing the way I shoot the gun, or strapped to the muzzle, and if something funny happens at the target, I can immediately check that shot on the chrono to see if it was me or the gun. Guess which is normally to blame ?

Also very good for doing complete shots strings / power curves, as you just fill up, shoot to your heart's content, and then look at the string on your phone.

[madcarlos]

Hopefully better than thier guns.

[Jesim1]

hopefully better than thier guns.

[Trumpetier]

Hopefully better than thier guns.

Aren't there chronos a bit hit and miss also ?

[rapidresponse1]

Always fancied one

[EricP]

According to one seller, if you are using the new version 2 with .177 then it has to be clamped to the barrel no more than 2” (5cm) from the muzzle. As a retired Radar engineer that suggests to me a lack of sensitivity as the radar cross section of the rear end of a pellet should be good as there are elements of a flat plate and corner reflector, assuming they are using the 76GHz automotive radar band.
I don’t know whether it would like being clamped to a springer. FX make PCPs so probably only think of those.

[Shed tuner]

never had any sensitivity issues with mine and .177s...

[ashf9999]

never had any sensitivity issues with mine and .177s...

Likewise.

[EricP]

Are you using version one or the new smaller version 2?