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Author Topic: HRM accuracy  (Read 13263 times)

Longjog @ GS-Sport-Servicecenter

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Re: HRM accuracy
« Reply #45 on: February 20, 2012, 04:44:27 am »

Hi gerhard,

I also assume there was a problem in production, but I believe it is a generally problem of this belt. First I used my old belt from GH-625M. First this was okay, but then after a while the HR-problem did appear.
I used the belt which came with the test-model GH-625XT in the box. The first run, problem seems solved. HR was okay. But the second run there was the problem again. Mabe there is a charge of belts whre the problem appears very early or where it is always there from beginning.
I think the quality of this belt is not okay. It doesn´t have a CE-singn which normaly is a "must to have" if you want to distribute products in Europe.

Best regards

Longjog

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TWG_TECH8

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Re: HRM accuracy
« Reply #46 on: February 21, 2012, 02:40:43 am »

Hi gerhard,

I also assume there was a problem in production, but I believe it is a generally problem of this belt. First I used my old belt from GH-625M. First this was okay, but then after a while the HR-problem did appear.
I used the belt which came with the test-model GH-625XT in the box. The first run, problem seems solved. HR was okay. But the second run there was the problem again. Mabe there is a charge of belts whre the problem appears very early or where it is always there from beginning.
I think the quality of this belt is not okay. It doesn´t have a CE-singn which normaly is a "must to have" if you want to distribute products in Europe.

Best regards

Longjog

Dear Longjog,

We have measured the waveform on both GH-625M and GH-625XT. They seems are the same. So perhpas the problem comes from belt.
We purchase the belt from a big factory which also sells to many channels with other brand. For sure they provided the CE, FCC report for us.


Sincerely,

Geoffrey
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Longjog @ GS-Sport-Servicecenter

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Re: HRM accuracy
« Reply #47 on: February 21, 2012, 05:05:55 am »

Hi Geoffrey,

thank you for the information. The product must be marked with the CE-sign itself. Report allone is not enough. Manufactorer should know this.

Can you ask the manufactorer if something has changed in the production-process or do they have changed some parts inside or the electrodes?
The early belts were okay at the beginning. The problem seems to appear only at older belts which have been used for a while and at the new belts which came with the test-watches.
As the electrodes have an abrasion, they could be the reason also. Maybe the manufactorer has changed something with the electrodes?

Maybe the problem was solved in the meantime and the belts which are delivered with the watches now are okay.

I am sure now the HRM-problem isn´t a software-problem. You not need to offer more time to improve the HRM-accuracy by firmware.  ;)

Best regards

Longjog
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partyman66

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Re: HRM accuracy
« Reply #48 on: February 22, 2012, 01:34:19 am »

LongJog's posts over the past few weeks about using different heartbeat straps with his GH625-XT watch gave me the idea/motivation to try the same thing and report my results with a heartbeat monitor strap from a different vendor... so here they are:

I've been experimenting over the past 8-10 days by alternating back and forth between 2 different heartbeat monitor chest straps on successive runs, while using my Globalsat GH625-XT watch to pick up and record the data in both cases.  The first of the heartbeat-monitor straps that I used is the one that came packaged with my GH625-XT, and the other is one that I already had from an old Oregon Scientific SE212 heartbeat monitor watch.  The Oregon Scientific strap is very old, and I used to use it somewhat extensively for a 2 to 3 year span about 6 or 7 years ago, but stopped using it since then and only recently put a new battery in it and started toying with it again in order to test out some things with the GH625-XT watch(in hopes of helping to isolate and troubleshoot the issues many of us are experiencing with the Globalsat heartbeat monitor strap).  To begin with, I was very pleased to find out that this old Oregon Scientific heartbeat monitor was even able to sync up and send data to my GlobalSat watch.

From my experiences with the GH625-XT heartbeat monitor strap, I can without a doubt, say that it is very inaccurate... so much so that the data it reports while working out is not accurate enough to actually be useful.  There seems to be unexpected huge peaks and dips in my recorded heartbeat with about an average 1.5 minute (generally a range of between 55 and 120 second) interval between one low point, the following unexpected peak, and the next extreme low point.  I'm not sure why this seems to be happening, but it does appear to regularly happen mostly on average in 1.5 minute intervals during my runs with the GH625-XT heartbeat monitor.  This is all during a workout that was a relatively smooth and consistent pace without any significant hills on my course.  I'm a 34 year old runner, and the Globalsat heartbeat strap seems to indicate that my average heartbeat on my runs is between 181 to 185 beats-per-minute for the duration of the entire run, with wild peaks up to 200 and dips down sometimes even to as low as 150 within numerous short (less than 2 minute) time spans.  The heart BPM readings do not seem to coincide at all with how I feel during my runs based on my level of physical exertion while using the Globalsat GH625-XT heartbeat monitor strap.

On the runs in which I used my Oregon Scientific heartbeat monitor strap in conjunction with my GH625-XT watch, I got very reasonable and stable results.  My heartbeat seems to be where I would expect it to be for my level of physical exertion during the run and the few peaks that I encountered mostly coincided with me going up a large hill or picking up the pace for a few minutes during the run.  It seems to indicate an average heartbeat of about 168-171 during most of my runs, with a range of about 165 to 176 for variation between any peaks and dips, except for areas of the runs where I intentionally picked up the pace for a few minutes for the purposes of testing the upper echelons of the heartbeat range during my otherwise consistently-paced run.  The heart BPM reading on my watch seems to also accurately reflect how I feel during the run at various points when I pick up the pace slightly while using the Oregon-Scientific heartbeat monitor strap.

Here is a screenshot of my heartbeat results from tonight's run with the Oregon Scientific heartbeat monitor strap on a short 4.05 mile run at a relatively comfortable pace(24 minutes, 26 seconds to complete run) and the curve NOT smoothed.  I did intentionally pick up the pace a noticeable amount for about a 70 second stint at about the 11 minute mark of this run to test some higher heartbeat ranges in my data on this run, and also sped it up a little bit for the last 4 minutes of the recorded portion of the run:





And here is the heartbeat plot from another run along the same exact route at a similar but slightly slower pace but using my GH625-XT heartbeat monitor (24 minutes, 44 seconds to complete the run), and the curve NOT smoothed:



I'm going to continue testing back and forth for another few days, but it seems relatively conclusive to me based on my testing that there is a hardware problem with the GH625-XT heartbeat monitor strap.
« Last Edit: February 22, 2012, 01:55:52 pm by partyman66 »
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canadien

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Re: HRM accuracy
« Reply #49 on: February 22, 2012, 03:53:41 pm »

partyman and all,

Just to be sure, is there at least one person who make their testing with a new battery into 625xt belt. Reason is the problem might be due to the time HRM belt lay without being use in the warehouse. So this is just to make sure the problem is the sensor itself and not the battery. After all it is strange that one of longjog's training
started good and did more and more badly during his training.

I am going to buy and test tomorrow...
« Last Edit: February 22, 2012, 10:21:10 pm by canadien »
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partyman66

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Re: HRM accuracy
« Reply #50 on: February 22, 2012, 05:06:58 pm »

partyman and all,

Just to be sure, is there at least one person who make their testing with a new battery into 625xt belt. Reason is the problem might be due to the time HRM belt lay without being use in the warehouse. So this is just to make sure the problem itself is the sensor and not the battery.

I am going to buy and test tomorrow...

I've been using the original battery that it came with.  I usually try to avoid opening up my heartbeat monitors at all costs(unless the battery is completely dead), because they seem to never seal quite as well as they were from the factory and eventually leak and die out once sweat works its way into them after a few very vigorous and sweaty workouts.... or at least this has been the experience I've had with previous running watches and heartbeat monitors.  I probably won't use the Globalsat one that much anyways if it continues to exhibit such erratic data production, so might as well give it a shot since I have little to lose.  Do the GH625-XT heartbeat monitors use the typical CR2032 battery?  I looked in the users guide and it did not mention the type of battery used by the heartbeat monitor strap.  This information should probably be added to the next revision of the user manual.
« Last Edit: February 22, 2012, 05:14:40 pm by partyman66 »
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canadien

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Re: HRM accuracy
« Reply #51 on: February 22, 2012, 05:20:18 pm »

yes 2032 battery. Most likely available at the dollar store...

Just make sure that the washer is well into place and you should have no issue with the sealing.

If it does not work for me I'll give my belt a little chirurgical dremel and do some DIY troubleshooting  :)
« Last Edit: February 22, 2012, 05:23:15 pm by canadien »
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partyman66

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Re: HRM accuracy
« Reply #52 on: February 23, 2012, 04:05:18 am »

I bought a new CR2032 battery tonight and put it in my GH625-XT heartbeat monitor and went for a run on the same 4.05 mile course that I've been using as a test platform for my Heartbeat monitor analysis.  I was running late at night in the dark and kept looking down at my watch to see my heart-rate every minute or so during the run, so I kept having to turn the watch back-light in order to see my heart-rate.  Unfortunately, at around the 12:40 mark of my run, I accidentally must have hit the pause button on my watch with my wrist while checking my heart-rate, and it stopped recording. I didn't notice it had stopped recording until about 5 to 6 minutes later, at which point I un-paused it the watch and logged the remainder of my run.  Basically there is a chunk of about 1 mile worth of this run that did not get recorded, but you can still get an idea of the heartbeat data that was recorded using the new battery.

My pace was slightly faster tonight than it was on last nights run, but only by about 5 seconds per mile.... nothing too drastic, but my heartbeat still indicated much higher than it should have been and often times I would look down at the watch and see 195 BPM indicated on the watch when it was probably really about 172-175.  195 BPM could not be anywhere near close to accurate based on my level of physical exertion at any point during this run.  As far as I can tell, the heartbeat monitor is still very inaccurate with the brand new battery installed, and it still exhibits the erratic spikes and dips in recorded heart-rate about every 1.5 minutes on average.

I'm going to do the same route one more time tomorrow using the GH625-XT heartbeat strap with the new battery in it, and try to run slightly slower than I did tonight to see what the results are.

Here is the heartbeat plot from tonights 4.05 mile run using my GH625-XT heartbeat monitor with a brand new battery and the GH625-XT watch(24 minutes, 4 seconds to complete the run), and the curve NOT smoothed:




I did notice that with the new battery, my watch seems to beep louder with the pace of my heartbeat than it used to with the original battery.  This could be indicative of the original battery being weak, or it could just be that when I installed this battery, it had a better contact connection with the terminals inside the heartbeat monitor than the original one did.  I used an Energizer CR2032 battery as a replacement that I purchased at Wal-Mart in a 2-pack for about $4.50.
« Last Edit: February 23, 2012, 04:11:08 am by partyman66 »
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canadien

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Re: HRM accuracy
« Reply #53 on: February 23, 2012, 04:29:00 am »

Thanks partyman, at least we know that the battery is not the issue...
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canadien

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Inside the strap
« Reply #54 on: February 23, 2012, 11:32:12 pm »

I decided to take my dremel and pry apart my erratic HR strap. At my surprise they were more electronics than I thought it would. And since I don't remember a thing of my electronic college course ::) :P I can't really help troubleshoot but at least it is always interesting to see how it is made inside.



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partyman66

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Re: Inside the strap
« Reply #55 on: March 02, 2012, 08:32:18 pm »

I decided to take my dremel and pry apart my erratic HR strap. At my surprise they were more electronics than I thought it would. And since I don't remember a thing of my electronic college course ::) :P I can't really help troubleshoot but at least it is always interesting to see how it is made inside.

Interesting to see what the guts of this thing look like.  There's a chance that the problem could be in the arms of the heartbeat monitor as well.  I believe that's where it actually picks up the signal of your pulse, and the center unit only manages and records that data.  I've noticed that the part of these arms which protrudes a bit (on the side which touches your chest) seems to be significantly smaller in terms of surface area than the other heartbeat monitors I've seen.  I compared it to my Oregon Scientific heartbeat monitor strap and I would say the surface contact area of the section that picks up the signal is about 20-25% smaller on the Globalsat heartbeat monitor strap.
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canadien

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Re: HRM accuracy
« Reply #56 on: March 03, 2012, 12:52:36 am »

yes but what I do find strange is that the behavior of the strap sometimes depend on if your moving or not.
I wonder why cause there is no accelerometer in it...

If it was the surface we should not have same problem with old 625m belts which is not the case.


And I might have one barely use and working fine strap around to give out. Let me know if interested...


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Longjog @ GS-Sport-Servicecenter

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Re: HRM accuracy
« Reply #57 on: March 03, 2012, 03:56:28 am »

Hi,
I see it like you. The electrodes are the most prone part of the HRM-belt.
Maybe this can be checked with some electrode gel for a better contact with the skin.
(How to get a worse belt running.)

But indeed it is the belt which is causing the problems and not the algoryhm in the Firmware. GS is in contact with the supplier.

Have a nice weekend.

Unfortunately I´m injured and won´t be able to run, maybe for weeks (how can I survive this??) :(

Longjog
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partyman66

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Re: HRM accuracy
« Reply #58 on: March 03, 2012, 07:06:44 pm »

If it was the surface we should not have same problem with old 625m belts which is not the case.

I don't personally own a 625M and have never seen the 625M heartbeat monitor belt.  How does that compare to the 625XT belt in terms of size and shape of the arms and the surface area of the part that reads the pulse?
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canadien

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Re: HRM accuracy
« Reply #59 on: March 04, 2012, 04:58:54 pm »

@partyman,

it is the exact same belt, no difference

@longjog
Good recovery Longjog! It is always hard on the mind. It was my worst sport winter season because of intensive digestive/gastric problem.
I even tought about stopping doing any kind of sports. Hope it does.not go as far for you.

Hope the best,

canadien
« Last Edit: March 04, 2012, 07:49:44 pm by canadien »
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