Oregon Scientific GR101

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Product information:
+
== Product information ==
  
 
http://au.oregonscientific.com/cat-Sports-and-Health-sub-Body-Weight-Scales-prod-Digital-Scale-with-Body-Mass-Index-and-Remote-Display-unit.html
 
http://au.oregonscientific.com/cat-Sports-and-Health-sub-Body-Weight-Scales-prod-Digital-Scale-with-Body-Mass-Index-and-Remote-Display-unit.html
  
Manual:
+
== Manual ==
  
 
http://au.oregonscientific.com/ulimages/manuals2/GR101.pdf
 
http://au.oregonscientific.com/ulimages/manuals2/GR101.pdf
  
Research:
+
== Research ==
  
 
<source lang="text">
 
<source lang="text">
Line 89: Line 89:
  
  
Limitations:
+
== Limitations ==
  
 
RFXCOM claims that the RFXtrx does support the GR101 (weight only), but at least for my GR101 my RFXtrx (firmware v50) doesn't get the weight right.  
 
RFXCOM claims that the RFXtrx does support the GR101 (weight only), but at least for my GR101 my RFXtrx (firmware v50) doesn't get the weight right.  
Workaround: None - request a bugfix from FRXtrx if affected.
+
Workaround: None - please request a bugfix from FRXtrx if affected.
  
 
RFXCOM's RFXtrx currently (firmware v50) does not support the decoding of the impedance.
 
RFXCOM's RFXtrx currently (firmware v50) does not support the decoding of the impedance.
Workaround: None - request it as a feature from RFXCOM.
+
Workaround: None - please request it as a feature from RFXCOM if interested.
  
 
Tanita's formulas might be patented. Therefore, the plugin for the GR101 is only available as DIY-ware: You have to insert Tanita's formulas into the plugin yourself ...
 
Tanita's formulas might be patented. Therefore, the plugin for the GR101 is only available as DIY-ware: You have to insert Tanita's formulas into the plugin yourself ...
  
  
Requirements:
+
== Requirements ==
  
 
tbc
 
tbc
  
  
Downloads:
+
== Downloads ==
  
 
tba
 
tba
  
  
Installation:
+
== Installation ==
  
 
tbd
 
tbd
  
  
Further reading:
+
== Further reading ==
  
 
tbc
 
tbc

Revision as of 20:47, 30 September 2012

Before jumping on the bandwagon, PLEASE read the section 'Limitations'.


Contents

Product information

http://au.oregonscientific.com/cat-Sports-and-Health-sub-Body-Weight-Scales-prod-Digital-Scale-with-Body-Mass-Index-and-Remote-Display-unit.html

Manual

http://au.oregonscientific.com/ulimages/manuals2/GR101.pdf

Research

 Hacking the GR101 revisited (see [0]) or: 
 How to convert the raw impedance reading from a GR101 to percentage body fat and percentage body water - by Ap15e
 
 
 Definitions:
 
 raw_impedance: data from GR101
 BD           : Body Density [kg/m^3]
 FFM          : Fat Free Mass [kg]
 Wt           : Weight [kg]
 Ht           : Height [cm]
 Z            : Impedance [ohm]
 %fat         : percentage body fat [%]
 %water       : percentage body water [%]
 
 
 Constants (best fit to formulas for data from a spreadsheet publicly available, see [1])
 
 impedance_factor = 39.198
 hydration        = 0.728895
 
 
 Formulas for males and females
 
 Z = raw_impedance / impedance_factor
 %water = ( Wt - %fat / 100 x Wt ) x hydration / Wt x 100
 
 
 Formulas for males
 
 BD = 1.100696 - 0.107903 x Wt x Z/Ht^2 + 0.00017 x Z [Tanita Corporation, see [2]]
 %fat = ( 4.57 / BD - 4.142 ) x 100                   [Brozek, see [3]]
 
 Additional formulas for percent body fat:
 
 %fat = ( 4.95  / BD - 4.5   ) x 100                  [Siri, see [3]]
 %fat = ( 4.374 / BD - 3.928 ) x 100                  [Schutte; for African-Americans, see [3]]
 %fat = ( 4.86  / BD – 4.39  ) x 100                  [Wagner]
 
 
 Formulas for females
 
 FFM = 13.96674 + 0.348613 x Ht^2/Z + 0.168998 x Wt   [Tanita Corporation, see [2]]
 %fat = ( Wt - FFM ) / Wt x 100
 
 
 Notes
 
 The formulas for males (Brozek) match the values on the remote display to a high degree 
 (error is < 0.5% for %fat and < 0.3% for %water for the data from the spreadsheet).
 
 The formulas for females yield higher errors. There is insufficient data in the spreadsheet 
 for further analysis.
 
 
 References
 
 [0] http://www.fabienletort.com/blog/2008/domotic-help-us-hack-the-gr101.html
 
 [1] http://spreadsheets.google.com/ccc?key=pQy-b-0ho4QdU4ecNy0TLLg&hl=fr
 
 [2] Jebb SA, Cole TJ, Doman D, Murgatroyd PR, Prentice AM.
     Evaluation of the novel Tanita body-fat analyser to measure body composition by comparison with a four-compartment model.
     Br J Nutr. 2000 Feb;83(2):115-22.
     PMID:10743490
     Abstract: http://www.ncbi.nlm.nih.gov/pubmed/10743490
     Full text: http://journals.cambridge.org/abstract_S0007114500000155
     NOTE: The unit of measure for the height in the formula for body density is cm, not m.
 
 [3] The Process of Physical Fitness Standards Development 
     Full text: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA495349


Limitations

RFXCOM claims that the RFXtrx does support the GR101 (weight only), but at least for my GR101 my RFXtrx (firmware v50) doesn't get the weight right. Workaround: None - please request a bugfix from FRXtrx if affected.

RFXCOM's RFXtrx currently (firmware v50) does not support the decoding of the impedance. Workaround: None - please request it as a feature from RFXCOM if interested.

Tanita's formulas might be patented. Therefore, the plugin for the GR101 is only available as DIY-ware: You have to insert Tanita's formulas into the plugin yourself ...


Requirements

tbc


Downloads

tba


Installation

tbd


Further reading

tbc

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