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FX Chrony's don't work with fans????

Forums › All Other Equipment › FX Chrony's don't work with fans????

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  • May 31, 2021 at 3:38 pm Link

    Saltlake58
    Participant
    Member
    United States
    Accuracy: +64

    So, I'm tuning my gun in a wood shed. Everything is working just fine, no problems.  Then . . . . .

    It's hot today, so I turned the fan on.

    Now, nothing works.  The chrony hasn't moved, but it won't pick up the pellets and give a reading.  So, I think to my self, it's Doppler Radar.  Doppler measures changes in the air.  Fans push air all over the place.  Maybe I should turn off the fan (in fairness, it's a high powered fan to dry carpets).  Magically everything starts working again.

    Anyone else had problems with "Air Movement" impacting the FX Chronographs?

    • This topic was modified 11 months ago by  Moderator5.
    May 31, 2021 at 3:51 pm Link

    Blackpaw
    Participant
    Member
    United States
    Accuracy: +26

    Depending on the type of fan you have it might be interference with electrical inter fence in the connection between the Chrony and your phone.

    May 31, 2021 at 5:37 pm Link

    Saltlake58
    Participant
    Member
    United States
    Accuracy: +64

    It's a squirrel cage fan.  I aimed it up and then things started working again.  Doppler measures changes in the air, so my bet is the air from the fan disturbed the chrony's ability to measure.  It's putting out quite a breeze, so probably a 25 or 30 mile an hour wind at the fan.  

    May 31, 2021 at 9:36 pm Link

    2L8
    Participant
    Member
    United States
    Accuracy: +17

    I notice a difference in readings between testing in my small shop and shooting outdoors. Outdoors gives me a slower reading on the FX chrony, all else being equal.

    June 1, 2021 at 3:05 am Link

    uhfradarwill
    Participant
    Member
    United States
    Accuracy: +6

    Oh boy, don't get me started on the workings of Doppler Radar!!😁

    June 1, 2021 at 8:29 am Link

    Saltlake58
    Participant
    Member
    United States
    Accuracy: +64

    OK, so after seeing your moniker (UHF RADAR WILL), I assume you did Radar somewhere.  without being too technical (remember I'm not a fluids engineering type), could a high speed fan screw up the doppler in the chronograph?

    many thanks,

    June 1, 2021 at 12:56 pm Link

    2L8
    Participant
    Member
    United States
    Accuracy: +17

    Will, Do share your insights !!!👀 We are all ears 👂👂👂

     

    Patrick

    June 1, 2021 at 11:44 pm Link

    triggertreat
    Participant
    Member
    United States
    Accuracy: +14

    Good to know!  I test in a wood shed as well and use the same type fan.  I have been on the fence about this chrono since they were introduced.  My Prochrono digital works very well in the shed with light kit, and the fan…

    June 2, 2021 at 1:40 am Link

    fe7565
    Participant
    Member
    United States
    Accuracy: +55

    Pretty sure it's not the air movement unless the air is moving and flapping something solid. But the moving fan blades if hit by he radar waves can reflect back and "confuse" the signal processor.

    • This reply was modified 11 months ago by  fe7565.
    June 2, 2021 at 8:03 am Link

    Saltlake58
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    United States
    Accuracy: +64

    fe7565

    Pretty sure it's not the air movement unless the air is moving and flapping something solid. But the moving fan blades if hit by he radar waves can reflect back and "confuse" the signal processor.

    it's a squirrel cage fan (one of the round fans without blades) about 8 feet behind the table where I have the chrony setup.  I fire away from the fan into the backstop.  The fan is high velocity, puts out a lot of air.  It's the type used for drying carpets.

    If I remember correctly, Doppler Radar measures changes in air density or movement.  (if anyone can correct that, please do!)

    Anyway, all I know is fan is running, nothing shows up on chrony.  Fan is off, chrony works.  Considering the technical nature of Doppler Radar, I'll probably never really understand the cause, but knowing the fan impacts readings is the important thing.  

    June 2, 2021 at 2:51 pm Link

    fe7565
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    United States
    Accuracy: +55

    Radar waves get reflected from dense objects and the reflected frequency difference (doppler-effect) is processed to calculate distance and velocity. The FX Chono only calculates velocity and the object should be straight in front of the antenna to get accurate velocity results.   If there are no moving parts in the fan exposed to the radar, what could be happening is that the air movement you are talking about has lots of small particles  (saw-dust, pollen, metal particles, heavy water vapor) which are reflecting to the radar.  Normally the air is not dense enough to reflect at such short distances.  We are talking about a few feet. 

    Take the fan outside to open space along with the FX chrono and try. 

    • This reply was modified 11 months ago by  fe7565.
    June 3, 2021 at 8:07 am Link

    Saltlake58
    Participant
    Member
    United States
    Accuracy: +64

    fe7565 – Your explanation sounds like it could be the cause at least from my limited experiments.  It just means I need to adapt and work with the chrony to get accurate readings.  

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