difficulty calibrating the logger

Aaronia GPS and Data-Logger (also logging/including: Gyro, Tilt, Air Pressure, Height, Speed, Digital Compass)

difficulty calibrating the logger

Postby johnscol » Tuesday 6. October 2015, 11:49

hi
i've got the GPS logger, and i'm struggling to calibrate it. I've been through the calibration process a number of times, using both the methods in the manual but whenever I turn the logger switch on (after the main power switch) the power light goes from steady green to fast flashing orange, and no logger light. The logger light is working, it lights while charging. The unit does seem to log to the SD card but sensor data is unreliable. Any ideas what i'm doing wrong or how I can factory reset it

thanks

colin
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Re: difficulty calibrating the logger

Postby Moderator » Tuesday 6. October 2015, 12:06

About which sensor data are you speaking and what do you mean with "unreliable"?
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Re: difficulty calibrating the logger

Postby johnscol » Tuesday 6. October 2015, 18:15

hi

I'm looking at the gyro data in detail, as i'm trying to intergrate it to provide bank angle, and i see values offset from zero by different amounts each time i use it. i also see some spike values (tipically 255, which i guess is max). i can code around these issues, but i wanted to make sure the unit was calibrated correctly before doing so.
is it possible to reset the unit, so i can get it logging as descripted in the manual, or am i mistaken

thanks

colin
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Re: difficulty calibrating the logger

Postby Moderator » Tuesday 6. October 2015, 18:32

You can not "rest" the Gyro to a "factory setup", this does not exist and would make no sense. Every calibration you do will stay until you start the next calibration. It is the same preocedure as smart phones need to calibrate the digital compass.

For sure you need to average the data output (set it to maximum logging rate for best results), just as posted in viewtopic.php?f=39&t=1633
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Re: difficulty calibrating the logger

Postby johnscol » Wednesday 7. October 2015, 11:09

ok, i understand what you are saying about the data. are you able to help me the the calibration process, as my main issue is that the when i turn on the logger switch (after the power switch) the power light flashes as if in calibration mode, and the logger light does come on.

thanks

colin
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Re: difficulty calibrating the logger

Postby Moderator » Wednesday 7. October 2015, 13:06

See MANUAL: The "flicker" is the recording speed (also see posting viewtopic.php?f=39&t=1623)
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Re: difficulty calibrating the logger

Postby johnscol » Wednesday 7. October 2015, 19:47

thank you.

i've read the online manual, its different to the one on the software CD, at least i know now.

the power light flicker indicates logging rate, and calibration mode, so maybe it is calibrating ok, but i dont get a logger light, when the log switch is turned on, just the power light flicker. is that correct?

colin
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Re: difficulty calibrating the logger

Postby JonC » Thursday 8. October 2015, 00:02

Hi Colin,

This confused me at first when I got my logger.

The LED above the Logger On/Off switch shows charging state of the battery, Red charging, Green charged.

The LED above the On/Off switch shows Green when it's on, and flashes Green/Red at the sample rate (fast) when's it is logging data or in calibration mode.

The LED on the nose is the GPS status, Red for acquiring satellites and Green when it is locked on.

Hope that helps,

Jon.
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Re: difficulty calibrating the logger

Postby johnscol » Friday 9. October 2015, 21:54

jon,

thanks for that. do you find your rest state values are the same each time you turn the unit on, mine seem to show difference each time

some great firmware suggestions too, i've been struggling to code around the variable number of samples per second too

colin
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Re: difficulty calibrating the logger

Postby JonC » Saturday 10. October 2015, 23:20

Hi Colin,

I have to admit, I haven't really compared the initial rest values on different days. With the setup I am using the GPS logger is used in a different place each time, not always level, so the initial rest values would probably be different for me anyway. I will however do some trials over the next few days to see how it is. What data is it specifically that is different for you?

Remember, the barometric pressure will usually be different on different days due to the atmospheric conditions. The compass I am struggling to get any sensible data at the moment, which may be due to the GPS logger not being level. I have done a trial with it on a level surface and compared heading with my iPhone, and it is wildly different and variable, so I need to do some research there to find out why. Maybe I haven't carried out my calibration properly?

What use are you intending to use your GPS Logger for?

Jon.
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Re: difficulty calibrating the logger

Postby johnscol » Monday 12. October 2015, 09:57

hi jon

we are trying to log bank angle and G load for an aircraft test. i'm trying to intergrate the gyro data so it can be used with the G data to provide a bank angle, but i see different values to resting state for the gyro. Also trying to intergate the data when you dont know if you are getting 30 or 31 records a second is also providing difficult. averaging the data over a minute and intergating works to a point but its dangerous mathatically.

thanks

colin
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Re: difficulty calibrating the logger

Postby JonC » Monday 12. October 2015, 11:29

Hi Colin,

I am also using for flight analysis. The gyro is very noisy and sensitive, so you will probably need to add some form of filtering or smoothing of the data during processing. The gyro sensor has its own filters, which hopefully with a firmware update we will be able to select a filter and get better data.

Hopefully we can help each other out in the future.

Where are you based?

Jon.
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Re: difficulty calibrating the logger

Postby johnscol » Monday 12. October 2015, 15:08

hi jon,

I'm in essex,UK

yes it is noisy. today by droppng the rate to 10/sec , doing some averaging , intergating the data with time, and then filtering it against the tilt values from the accel i've got something that is follows whats happening to some extent for bank angle, I've also rewrote the data files with time stamps rather that update counts based on the number of updates per second which seems to help the quality of the gyro intergation. but i'm still struggling with start values

these are tipical of my start values, what do you see

$PAAG,DATA,G,092849.3,-52,5,-11,A*0C
$PAAG,DATA,T,092849.3,-127,1,7681,A*0D




as an aside i also get a few bits like this with suspect sequence numbers and records possibly arriving in the wrong order, which is proving diffcult to deal with.

GPRMC,090025.000,A,5136.3056,N,00028.8499,E,0.01,4.71,121015,,,A*62
$GPGGA,090025.000,5136.3056,N,00028.8499,E,1,5,1.88,24.8,M,47.0,M,,*6C
$PAAG,DATA,G,090025.0,-86,8,1,A*17
$PAAG,DATA,T,090025.0,-5567,961,5761,A*39
$PAAG,DATA,C,090025.0,120,-376,-454,A*0D
$PAAG,DATA,B,090025.0,1015.278,0,0,A*2E
$PAAG,DATA,G,090025.2,-86,9,1,A*14
$PAAG,DATA,T,090025.2,-5695,1,5185,A*36
$PAAG,DATA,C,090025.2,121,-379,-455,A*00
$PAAG,DATA,B,090025.2,1015.278,0,0,A*2C
$PAAG,DATA,G,090025.4,-86,18,1,A*22

and

$PAAG,DATA,T,091037.8,6465,-1087,5121,A*01
$PAAG,DATA,C,091037.8,116,407,-170,A*2D
$PAAG,DATA,B,091037.8,1014.3493,0,0,A*15
$PAAG,DATA,G,091037.0,-126,185,28,A*11
$PAAG,DATA,T,091037.0,6593,193,4929,A*18
$PAAG,DATA,C,091037.0,134,413,-139,A*2D
$PAAG,DATA,B,091037.0,1014.3493,0,0,A*1D
$GPRMC,091038.000,A,5136.3147,N,00028.8354,E,0.01,225.60,121015,,,A*69
$GPGGA,091038.000,5136.3147,N,00028.8354,E,1,9,0.98,33.1,M,47.0,M,,*65
$PAAG,DATA,G,091038.1,-202,128,-64,A*38
$PAAG,DATA,T,091038.1,6721,-959,4737,A*3F
$PAAG,DATA,C,091038.1,131,416,-147,A*2A
$PAAG,DATA,B,091038.1,1014.3493,0,0,A*13
$PAAG,DATA,G,091038.2,-70,57,-20,A*35
$PAAG,DATA,T,091038.2,6721,257,4801,A*1E
$PAAG,DATA,C,091038.2,127,419,-126,A*26
$PAAG,DATA,B,091038.2,1014.3493,0,0,A*10
$PAAG,DATA,T,090025.4,-6015,1025,5377,A*05
$PAAG,DATA,C,090025.4,119,-377,-454,A*02
$PAAG,DATA,B,090025.4,1015.278,0,0,A*2A





i'm
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Re: difficulty calibrating the logger

Postby JonC » Monday 12. October 2015, 16:29

Hi Colin,

I have just put my GPS logger level on a desk and let it find GPS signal for 5 minutes, then connected it to my laptop and recorded 45 seconds of data with the logger not moving. Here are my rest values.....

$PAAG, DATA, G, 150151, 11, 28, 34, A*33

That is typical for the 45 secs, with the values varying from 11-14 for the first value, 27-30 for the second value, and the third value staying at 34 all the time.

For the accelerometer it's not so stable .....

First value varies from -255 up to 769
Second varies from -703 up to 1153
Third varies from 7489 up to 8833

I haven't seen the anomolies you have with the odd sequencing, but will look out for it now. What I have just seen is my barometer recording 3 or 4 readings exactly the same, with the same time stamp and sequence number. I wonder if the processor is struggling? I'm recording at 10 samples per second, but only getting 9.

I'm up near Bruntingrhorpe but do travel to Essex a lot as I have family there.

Jon.
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Re: difficulty calibrating the logger

Postby JonC » Monday 12. October 2015, 16:48

I have just a calibration (not exactly sure if I've done it right though), and my rest values are now........

Gyro....
First varies 0-4, but does have a spike from -254 to +255 !!
Second varies 48-52
Third is solid at 34

Accelerometer...
First value -383 to 449
Second varies -383 to 1281
Third varies 7233 to 8321

Jon
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