must be doing sth wrong... no love with calib procedure

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michal
Posts: 10
Joined: Thu Oct 25, 2018 12:04 pm

must be doing sth wrong... no love with calib procedure

Post by michal »

Could someone please point out what I am doing wrong?

Set AP to profile 4, set it up for calib ride.
Make sure all sensors (speed, power) are active.
Force AP to pick-up sensors.
Upon completion, fire up Garmin head unit, search for AP as a power source - adding it upon finding it.
Click on the AP, roll down to start of calib ride. Stop. Go. Watts go to 50. Stop. Turn around. 70 W reached where it should be, finish should by 100W.
In theory calib ride finished - but as Garmin switches to "live data" power seems to be twice as it should be.
Frustrated (I know how 600W feels) I finish the ride. As I plugin the AP - I get 3 files. Attached.

What am I doing wrong?
Attachments
Velocomp_07_06_2020_1619_10_Miles.ibr
(172.15 KiB) Downloaded 158 times
Velocomp_07_06_2020_1613_2_Miles.ibr
(27.82 KiB) Downloaded 165 times
Velocomp_07_06_2020_1610_1_Miles.ibr
(12.23 KiB) Downloaded 177 times
Velocomp
Velocomp CEO
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Joined: Fri Jan 11, 2008 8:43 am

Re: must be doing sth wrong... no love with calib procedure

Post by Velocomp »

The power numbers you see on your Garmin are the DFPM numbers. So, it's your DFPM that is incorrectly reporting 600W!!

This is confirmed in the ride file.

What kind of DFPM are you using?

In your ride file, at the 7:51 mark, you stop pedaling briefly, then resume. When you resume pedaling your DFPM watts become normal. My guess is that, during the zero pedaling, your DFPM's calibration was corrected in the DFPM sensor. AP does not "touch" DFPM calibration.

AeroPod is working properly but, as we say in the instructions, your DFPM has to be calibrated too.

Let me know what kind of DFPM you have. That might suggest an approach to get things working.
Attachments
Screen Shot 2020-07-06 at 3.20.43 PM.png
Screen Shot 2020-07-06 at 3.20.43 PM.png (221.49 KiB) Viewed 3649 times
John Hamann
michal
Posts: 10
Joined: Thu Oct 25, 2018 12:04 pm

Re: must be doing sth wrong... no love with calib procedure

Post by michal »

John - it's a SRM (wireless); was activated and calibrated before I started the procedure of paring sensors with AP.
I have the auto-calib function set on for SRM - maybe that is a problem?
I was recording the whole ride on another device (Garmin Fenix) - attached is the file - and there are no power readings that go as high as 600W.
Attachments
5196716508.zip
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Velocomp
Velocomp CEO
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Re: must be doing sth wrong... no love with calib procedure

Post by Velocomp »

michal wrote: Wed Jul 08, 2020 7:32 am John - it's a SRM (wireless); was activated and calibrated before I started the procedure of paring sensors with AP.
I have the auto-calib function set on for SRM - maybe that is a problem?
I was recording the whole ride on another device (Garmin Fenix) - attached is the file - and there are no power readings that go as high as 600W.
That explains it.

For SRM power meters only, the calibration correction is done in the receiver, NOT in the SRM sensor. It makes no difference if auto calibration is set; this only means that your SRM bike computer receiver is recalibrating itself (not the SRM sensor) during the ride.

AP is another "receiver" of SRM power information. So, AP must be calibrated separately to the SRM.

Please read the AP instructions about using an SRM. SRM has a very different (and antiquated) way of calibration. You have to follow AP instructions exactly in order to get the SRM calibrated with AP.
John Hamann
michal
Posts: 10
Joined: Thu Oct 25, 2018 12:04 pm

Re: must be doing sth wrong... no love with calib procedure

Post by michal »

...the only thing is, that I do stick to that protocol to the letter - and as you can see from the FIT file - the other device never recorded those values.
Attachments
5196716508.zip
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Velocomp
Velocomp CEO
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Re: must be doing sth wrong... no love with calib procedure

Post by Velocomp »

SRM uses a very different, completely unique, and totally archaic way of calibration, called "crank-torque-frequency". What makes it so bizarre is that the calibration correction is not applied to the power signal transmitted by the SRM sensor; the correction is applied to the bike computer receiving the sensor signal.

What I think is happening is that you have two bike computer receivers; your Garmin, and AP (AP is, for this application is a bike computer receiver). It appears there is a calibration conflict between them.

For AP to correctly measure CdA, it must correctly read SRM power. This means that your AP must be paired and calibrated properly to your SRM. It's obvious that AP is not correctly calibrated to your SRM.

To fix this problem please do the following:

1) On your Garmin, remove the SRM as a power sensor. This means your SRM will no longer be calibrated by your Garmin.
2) On your Garmin, make sure AP is paired as a power sensor
3) Note that AP will rebroadcast power signals sent by the SRM. So, you don't "lose" anything by implementing step 1)
4) With AP as the only receiver of SRM signals, follow precisely the SRM pairing information on pages 9-10.
5) If you've done step 4 correctly, you will see good power signals on your bike computer.
6) Do a new cal ride

Please post a ride file.
Attachments
AeroPod_OPERATING INST 052220_index.pdf
(3.64 MiB) Downloaded 177 times
John Hamann
michal
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Joined: Thu Oct 25, 2018 12:04 pm

Re: must be doing sth wrong... no love with calib procedure

Post by michal »

Thanks for your patience - will do;

another thing - when AP is added to Garmin as power meter - there is also an option to "calibrate" AP via Garmin - can you use this function as well or is it there simply because Garmin makes this filed available for all devices recognised as power meter?
Velocomp
Velocomp CEO
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Re: must be doing sth wrong... no love with calib procedure

Post by Velocomp »

No, the Garmin calibration feature is intended only for DFPMs. It will have no functionality with AP.
John Hamann
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