Wow, those are some very, very, close results. 2.3 fps average difference between the "slowest" and "fastest" of the devices. From a curiosity standpoint, It would be interesting to know which is the closest to the true result though it hardly seems that this knowledge would have any real world effect.
By and large, with 2-3fps spread between units, determining truth with the equipment I currently have available just isn't a reality - even firing a truing test at distance, I'm quite confident I'm not sufficiently skilled to determine on target a difference in velocity of less than 2fps. As I mentioned above, by and large, based on these results, since all of the units agree within all practical application tolerances, either ALL of them are wrong, or ALL of them are correct.
It would also be interesting to know if the other chronos are off because they are less consistent in the readings from shot to shot and this results in random drift or if they are calibrated slightly off and the error is therefore consistent.
By and large, if any truth exists near or among these results, it appears, based on the nature of the dataset, there is significant indication of both offset AND random "drift" (not drift, but rather simple error). You can see in 1) the heatmap of the total 600 data points, 2) the 30 round non-chronological focused chart, and 3) the intrabrand data table above there's a prevailing order for each unit respective to one another. One of my LabRadar LX's read faster than the other ~2/3 of the time, LabRadars displayed the fastest speed 90% of the time, one of my Garmins read faster than the other ~2/3 of the time and the two Garmins were in the middle of the 3 brands 85% of the time, and the two Athlons gave the slowest readings 89% of the time, with one of the units reading faster than the other ~50% of the time. However, those trends were not 100%, 100%, 100%... The relative offset from one another persists a vast majority of the time, however, random error does swap and flop the order from time to time.
The athlons have a noticably better SD and ES than the garmin or labradar so they do look consistent if nothing else.
I'll be honest - this isn't my only data set with these devices, although at this time, it IS my largest set - I'm really, really surprised to see the smallest ES and SD from the Athlons. I will point out, however, having the smallest ES and SD in this particular test doesn't necessarily mean the Athlons were the tightest to truth. Considering the EXTREMELY bad ammo used for this test, the Athlons may simply be erring on the inside of the extremes. The Athlons DID display the highest variability between the two units, around twice the deviation between the 2 Athlons as I saw from the 2 Garmins.
I need to ask the athlon folks if these units can be software improved to implement frequency jumping when interference is detected. This seems like it would be likely possible as I expect the frequency generator is variable and set in firmware.
I can't speak from direct knowledge, but I also assume the channels are assigned within firmware, but I could be wrong. I could also understand if the $150 offset between the Athlon and the other brands was achieved by using a single channel transmitter. But Athlon has been quite straight forward in stating that they did not design the Velocity Pro's with high radar traffic firing lines in mind, and saved money in development and deployment in living single channel life.
Something I DO find interesting - in my own testing and that I have seen by others so far, it never seems to be Garmins interfering with the Athlons, but rather almost always seems to be LabRadars (or Caldwell VelociRadars, in my personal test). The Garmins do frequency hop when turned on (not sure if they do so mid-operation), so that alignment between the manual frequency swap LabRadar models (maybe Caldwells are fixed? Dunno yet) and NON-alignment with Garmins makes sense. Considering the current market, the interference opportunity would be relatively low - most PRS firing lines won't have many if any LabRadars present, rather a lot of Garmins, and the Garmins will move out of the way of the Athlons.
I would also be interested to know if they can display the analyzing loop interference when in adjacent lanes instead of on top of one another. Have you tried this? Given how these doppler chronos tend to see returns from adjacent lanes but ignore them as they can tell the signal is comming from a different lane, It is quite plausible they only throw each other off when right next to each other. Have you tested this? While interefering with each other when many are on the same lane together is a PITA for people testing chronos side by side for reviews, it wouldn't be a real world issue wheras interferance from the next lane over would be a pretty big deal for competitive shooters who are frequently on many person firing lines where everyone has a chrono up.
I have seen lane crossing interferences with Athlons as well as Garmins - and recognize that when the units are lane crossing the LabRadars and Caldwells, those units would be hiding the interference better than the Garmin or Athlons only because of their design - acoustic triggers will still interfere and produce false readings, they just don’t give false triggers to warn you that the interference is coming. The Athlons get stuck in the same re-triggering loop whereas the Garmins I have seen have not been so persistent, and rather are only reporting erroneous velocities (4k velocities for 2.8-3k loads).
Yes, I have tested some side by side data capture, rather than the vertical orientation I have pictured above. I will also offer more and more testing of this nature in the near future (big plans this week and weekend) so I can better demonstrate the sensitivities. Having the units farther spread apart will achieve 2 limits as the beams are peeled farther and farther apart 1) the Athlons are less persistently retriggered as they receive less concentrated radar false echo, 2) the units are better able to determine what is false echo vs. their own signal (report a bad reading vs. recording an incorrect velocity), and 3) eventually, moving sufficiently far apart, the beams will not false-echo back to each other and the false echoes and interference will be eliminated. On this particular day, the farthest outside Athlon did not appear to be interfering with any of the other 4 depicted (and has never interfered by 2 of those other units in subsequent testing), but did repeat 4150-60 fps readings, indicating reception of a false echo from another unit, when one of the other shooters was on the line in the bay beside us (I wanna say these are 11ft bays?).
I CAN state, in my experience so far, I do NOT believe that the chronic, persisting re-triggering loop will happen for any "real world" shooter on a 100yrd zero board or competition firing line, and only happens to those of us concentrating multiple units onto one rifle, BUT, I can also directly state experience in false-echo reception where ANY of these units have displayed a false velocity reading due to nearby radar interference - RARE, exceptionally rare, and extremely obvious, but it remains to be a reality for this kind of device. Not so different than finding out that someone put a shot or two on the wrong target when scoring after a match, just a reality of the practice.
