Mevo+ Spin measured vs calculated ?

[SPApex]

I am trying to figure out if I have a problem with my Mevo+.
What is the consensus for shots showing measured vs calculated spin rates? I am seeing about 30-40% measured spin rates using metal dot on ball. My setup is Short Indoors mode. When I use a Titleist RCT ball it measures almost all of the time but sometimes the spin shows double what it should. I am surprised using the dot that it doesn’t read spin as good or as often as the RCT ball. I believe most of the carry inaccuracy I am seeing may be spin related.

[bubbtubbs]

Have you tried doing any other dot configurations? Back on release, some people were doing two overlapping dots to make an oval, or cutting strips from aluminium tape.

I use the RCT and it's made an ok difference in spin but it wasn't terrible before with a single dot in my setup. Italicized readings 1 in 15 or less.

[SPApex]

Thanks for the reply!

[Bubba22]

This is a very good question. Now when we speak of spin, I suggest we consider both spin and spin axis which I think is the holy grail of indoor golf. We know that the unit measures the other ball characteristics with extreme precision to any photometric unit. I do think with the metallic dot or RCT balls the Mevo plus reads spin and spin axis directly when it can catch it. When it misses, then both spin and more importantly spin axis are likely calculated. Spin will be calculated based on all the other measured data (probably accurate the majority of the time). Spin axis will be calculated using the club metrics of swing path, angle of attack etc,. and ball direction. The unit cannot measure face to target which can be calculated with angle of attack and ball direction. This method would work out the majority of the time except when there is gear effect. That is the reason Trackman utilizes the camera ( they call it Optical Enhanced Radar Tracking as opposed to Fusion) to measure where on the face the ball is hitting so they can adjust the spin axis based on gear effect indoors. Flightscope is releasing something similar coming soon with their X3. This will tighten up some of readings when spin is missed indoors. If any Trackman users are here than can chime in to correct me. I do believe Trackman requires lighting for that feature. I would love to see Mevo plus also get that option of face contact. If one has the proper environment then the Mevo plus is a great unit for full swing.

[Mirek_62]

Trackman doesn't measure the point of impact on the face of the club with a camera. This is not technically possible either, as the club head is between the ball and the camera at the moment of impact. The camera is behind the ball and cannot see the club face.

https://blog.trackmangolf.com/club-data-definitions/

https://blog.trackmangolf.com/tracking-club-delivery-and-impact/

[Dan13]

One important point I think has been overlooked - radar units (TM or M+) never measure spin axis. Outside they can track sufficient ball flight to back calculate it from other measured parameters. Inside spin axis is always calculated from path and H launch and to some degree AoA. TM4 does attempt to use its camera to help determine impact location and gear effect. I assume the X3 will soon be doing something similar.

Anyhow the RCT ball can help with accurate spin numbers indoors but it cannot help with spin axis. I was really disappointed about that when I figured it out after the videos of the RCT ball came out. TM4 will get spin axis wrong in limited flight with off center hits ( w woods) if there is insufficient lighting for the camera to assist with impact location - even with a RCT ball. So that will continue to be a weakness of the M+. Solution I guess is to always hit the ball in the dead center if the face😬

[Mirek_62]

Dan13 I disagree that Trackman doesn't measure spin axis. In his materials he states that the spin axis is measured, not calculated. So does Flightscope if metal dots are used for indoor.

[Dan13]

I hope I am wrong but all of the research I have done to date says otherwise. I will see what references I can post here. If Trackman can measure spin axis directly why is it critical for it to have impact location? Because it using impact and the cog of the club to determine a calculated gear effect and from it spin axis.

[Mirek_62]

Trying to have a precise point of impact on the face may be related to a completely different reason. Camera-based competitors (with a direct view of the club face) offer this feature and Trackman must respond. A side benefit may then be the refinement of the measured data (not just the spin axis). If you look at what the radar output looks like, you will see that it is not that hard to find a matching pattern for the spin axis as well. If you know the point of contact on the face, it will refine the search area for the corresponding reflected pattern.

[Dan13]

I think the "proof" is that when impact location is not captured and a toe or heel strike occurs TM will miss the spin axis indoors badly because it assumes center contact without the influence of gear effect. The best example I can find of that is in a TXG video when they were testing TM vs Quad with the new RCT ball from Nov of last year. They use a Quad for their fittings and brought in a TM to compare spin indoors. Spin was bang on with the new RCT ball but the spin axis on off center hits was off because they did not have the lighting right for the TM's camera to assist with getting impact location. It was actually Ron from Gungho Golf that made that comment after they posted the video. Take a look if you have a chance.

[Dan13]

https://blog.trackmangolf.com/spin-axis/

Here is a good reference. It is not measuring it directly.

[Bubba22]

There is obviously a debate whether Trackman directly measures or calculates spin axis indoors. I am not sure the answer. On that same note, does Flightscope directly measure or calculates spin axis is indoors?

[Dan13]

On “in the weeds” questions like this I have gotten inconsistent responses from FS reps. I guess this is a level of nerdom/detail that is seldom brought up. I just want to understand the data the M+ is capable of producing. Knowing that gear effect cannot be properly determined without sufficient ball flight definitely falls into the good know category. Wonder if FS will elaborate on this when they roll out impact location for the X3. It’s a big deal for indoor spin axis w woods and a big differentiator from the M+.

[Bubba22]

I completely agree Dan13.

[Jfkervan]

I can’t agree more with Dan13. The motto of flightscope is that we can trust the data, but their customer support rep feedback -especially on the technical side when they lean in- is anything but trust building. It made me return my mevo+

Here is the response I got from I’ve of their technical reps after I raised concerns of 1500rpms with a 60 degree edge , going 65 yards with -4 aoa, 78 spinloft, and 72mpg club head speed - as one of (too) many outdoor measurements raising concern re: wedge spin…(removing name to protect his privacy)

“ […]

I have checked the spin readings and they seem to be correct. My name is xyz, and have done more testing on Flightscope spin than anyone else ever. You might not know this, but the lowest spins I have ever had was with a 60 degree, confirmed by high speed camera. Secondly, Just because its a Trakan, does't mean it measures spin better than a Mevo+. The Mevo+ units are very accurate.

Kind Regards.

Xyz”

Hmmm

[games]

SPApex I think this is a great question. You've realized RCT balls throw out an occasional "actual" double-spin read. My guess is if you get an estimated spin from an RCT ball, MEVO+ probably recognized its own "double spin" read, cut it in half and reported it as estimated. I do wonder if changing the club in the app helps...

BTW, for any OG MEVO users: Definitely change the club in the app, especially driver.

[Bubba22]

Spin and spin axis patents by Flightscope if someone wants to read and give us the Coles notes version.

https://patents.google.com/patent/US10775492B2/en?inventor=Henri+Johnson

https://patents.google.com/patent/US9868044B2/en?inventor=Henri+Johnson

[Mirek_62]

“#3.2
Dan13 commented
02-11-2022, 12:11 PM
One important point I think has been overlooked - radar units (TM or M+) never measure spin axis. Outside they can track sufficient ball flight to back calculate it from other measured parameters. Inside spin axis is always calculated from path and H launch and to some degree AoA.”

As I wrote once before, I disagree with Dan13 that Flightscope doesn't measure spin axis, but calculates it from club head parameters.
Patent Nos. US10775492B2 and US9868044B2 give me the benefit of the doubt.

Patent Nos. US10775492B2
„This disclosure provides a system and method to directly measure the ball spin axis from signals received in multiple spaced Doppler radar receivers, and can be used in a Doppler radar designed to measure the motions of a moving body, especially to measure the axis of rotational motion. This includes systems for measuring the movement and spin of sports balls, such as golf launch monitors. In this specification, the term “golf ball” is used but is intended to cover any spinning projectile that can be tracked in the air.
Thus, an example method includes detecting a launched golf ball; receiving reflected Doppler signals from the golf ball by a radar device having an array of multiple receiver pairs; demodulating the received Doppler signals from the multiple receivers; determining a time delay between the demodulated received signals for each of the receiver pairs in the array; calculating an average time delay for the multiple receiver pairs; calculating a spin axis of the golf ball from the time delay values; outputting a spin axis value to an external system; and storing the spin axis value in a database.”

[Dan13]

The patents describe a “new” way to actually measure spin axis. However this does not mean this tech is actually in use yet. The last date on the patent is from 9/2020. After X3 and M+ came out. The patents also describes the “conventional” way that spin axis is measured by radars which matches up my understanding and which I’ve described above. The patent also says the radar must have a multi array - which X3 does but M+ does not. I could not find a distance needed so even for the X3 it’s not clear if this can help with indoor spin axis which is the only place radar struggles with it.

The “big” news for the full swing kit when it was originally announced was that it was going to be the first radar to be able to measure spin axis directly through tech similar to this. Obviously that has not happened. I know FS and TM are working on it but I still believe their units are calculating spin axis until this tech can actually be implemented.

This whole discussion could easily be put to bed by someone with an X3 hitting a massive toe strike with an open face indoors with a driver and see if the get a draw spins axis. I don’t think you will…

[Mirek_62]

The last date of 9/2020 does not mean that the principle stated therein is no longer applied in the units sold.
That is just the date the patent was approved.
The patent application was filed on 10/2018.
You post more speculation than true information.

[Mirek_62]

The patent also says the radar must have a multi array - which X3 does but M+ does not.

Could it be a mistake in your information?

[bubbtubbs]

I think what they really meant was radar emitter and not receiver, since both X3 and TM have dual Doppler whereas M+ and other, consumer-level devices only have one.

Edit: this was answered below. I didn't read to the end.

[slicer231]

Just to correct the otherwise brilliant info in this discussion, X3 does not have dual doppler radars. It has a single 10 GHz radar with multiple receiver antennas, similarly to the Mevo+ (which has a 24 GHz radar).

[Dan13]

@Mirket_62. At this point I will make this my last post on this topic for awhile and leave it for someone with more street cred or reputation on this forum or radar knowledge to confirm or deny what I have been saying. On the pictures above it is the transmitter that is the piece in question not the receiver. Multiple signals go out in phased timing which the receivers can then interpret to directly measure spin axis which is a very tricky thing to do. I am by no means a radar expert but this is my understanding of generally how it works.

I am not sure if you agree with me or not on the TM but I think I have established that currently TM uses the camera to identify impact location which helps calculate spin axis indoors. It was the big improvement when the most recent version of TM came out a couple of years ago (not sure of the exact timing). That is TM's current solution to the indoor gear effect spin axis issue and from the reviews I have seen (limited) it works very well with good lighting. So they are not measuring spin axis directly.

Your position I believe is that X3 (and M+) are ahead of TM in this area and are currently measuring spin axis directly via the patent method you quoted from. M+ is a consumer level device that does not send out multiple signals like the big boys (X3, TM). This is a requirement for direct measurement of spin axis via the patent you quoted from. So this eliminates M+ as even having the capability to measure spin axis directly. The X3 does have the necessary hardware so it possible and is clearly something FS is working on. Since it is not something that FS trumpets as having over TM I don't think they are directly measuring spin axis. This concurs with the random comments that have come out from people using radar indoors, including X3, that gear effect is still an issue for the unit indoors. I had that exchange with Scott Hogan after he posted his original video on the Prop Package coming out for M+.

Lastly and again, this is all easily verifiable by using an X3 indoors and intentionally hitting it off center with a driver. The spin axis number will not take into account the gear effect, aka, it is not measuring spin axis directly.

Dan

[bubbtubbs]

Ah, I figured you were talking about the number of radars in the unit and not the receivers. Sorry I didn't read the entire thread before responding to the last post.

[Mirek_62]

Fu*k insults like "someone with more street cred", you're a world champion. HOWGH

[bubbtubbs]

I think it's important to recognise the intended usage of these devices and their limitations. Mevo+ was likely designed to be taken to an outdoor facility - range, course, whatever - and used there to read the ball flight.

The short indoor capability is an added bonus, but if it were intended to be plunked down inside and used purely as a simulator it would almost certainly have been designed with longer battery life (1.5h is a good range session), a longer charger cable setup, dual WiFi or Bluetooth/WiFi connectivity, etc.

It's a bit like buying a Subaru BRZ then claiming it's a terrible car because your quarter mile times suck.

[games]

Bubba22 I can speak to the second patent, but not as well as Ron at Gung Ho Golf who pointed it out to me on a different forum. That one was filed back in 2014, and it depends on a golf ball having a two-piece cover forming a seam. I've heard this technology kicks into MEVO+ when set to "Indoor" or longer flight settings. I fear its utility might be restricted as I think most "standard" ball manufacturing processes are moving to seamless covers.

Anyway, to utilize this technology, simply place the seam of your ball perpendicular to the target line. If I were using a Srixon QStar Divide, I'd set the ball so the line would point directly at me at address.