Small changes to README_coach.md

docs/README_coach.md

@@ -348,7 +348,8 @@ program in relation to improvements over time.
 motion analysis, most require athletes to wear sensors to acquire their posture
 data; however, this method easily introduces noise due to friction during motions
 
-[AUTOMATED ROWER ASSIGNMENT TO ROWING EVENTS: A MACHINE LEARNING APPROACH](https://commons.nmu.edu/cgi/viewcontent.cgi?article=2810&context=isbs)
+[Automated Rower Assignment to Rowing Events: A Machine Learning Approach](https://commons.nmu.edu/cgi/viewcontent.cgi?article=2810&context=isbs)
+[Analysis of indoor rowing motion using wearable inertial sensors](https://dl.acm.org/doi/pdf/10.4108/eai.28-9-2015.2261465)
 
 #### [Biorowtel](https://biorow.com/index.php?route=product/product&path=61_108&product_id=54)
 
@@ -365,6 +366,7 @@ data; however, this method easily introduces noise due to friction during motion
 * [Position-sensor](https://biorow.com/products/biorow_sensors/position_sensor) £380
 * [Foot-stretcher force sensor](https://biorow.com/products/biorow_sensors/stretcher_force2) £1,200
   [RBN info](http://www.biorow.com/RBN_en_2015_files/2015RowBiomNews02.pdf)
+  Biomechanics of Rowing: 2.5.3 Stretcher Force
 * [3D Pin Force sensor (Instrumented C-bracket)](https://biorow.com/products/biorow_sensors/c_bracket) £1,500
 
 #### DIY IMU
@@ -375,11 +377,24 @@ data; however, this method easily introduces noise due to friction during motion
 
 ##### Beacon for handle, seat and trunk
 
+| NRF chip | RAM | ROM | Notes |
+|----------|-----|-----|-------|
+| 52810    | 24k | 192k | BARELY enough RAM for "broadcast only" function |
+| 52820    | 32k | 256k | Untested, should work just as the 832 does |
+| 52832    | 64/32 KB | 512/256 KB | Enough RAM for additional sensors |
+| 52840    | 256 KB | 1 MB | Untested; probably overkill for this application |
+
 * 3x [holyiot 21014]() nRF52810 + lis2dh12 + RGB LED + button
 * [holyiot 21014 zephyr project](https://github.com/danielstuart14/wlen_project/tree/master/beacon/boards/arm/holyiot_21014)
+* [bthome-presence](https://github.com/kquinsland/bthome-presence/)  
+  firmware for presence detection that "just works" with Home Assistant.
+  The firmware targets the cheap nrf52 based BT LE tags that are available on
+  Ali Express.
+  * 
 
 ##### 3-axis load cell for foot spreader
 
+##### load-cell for the seat
 
 ### Video
 
@@ -389,10 +404,13 @@ using a simple camera.
 
 * [OpenPose](https://github.com/CMU-Perceptual-Computing-Lab/openpose)
   Real-time multi-person keypoint detection library for body, face, hands, and
-  foot estimation, with python api.
+  foot estimation, with [python api](https://cmu-perceptual-computing-lab.github.io/openpose/web/html/doc/md_doc_03_python_api.html)
 * [OpenPose Video](https://www.youtube.com/watch?v=OgQLDEAjAZ8)
 
-[Automatic Rowing Kinematic Analysis Using OpenPose and Dynamic Time Warping]()
+* Automatic Rowing Kinematic Analysis Using OpenPose and Dynamic Time Warping]
+  * [An introduction to Dynamic Time Warping](https://rtavenar.github.io/blog/dtw.html)
+  * [dtw-python](https://dynamictimewarping.github.io/py-api/html/index.html)
+In order to apply the DTW algorithm, we first need to choose a reference or desired rowing cycle. The paper above chooses to take the rowing cycle from a known good rower, we want to take the rowing cycle from the Biomechanics of Rowing book chapter 4: Technique.
 
 [Intelligent Performance Evaluation in Rowing Sport Using a Graph-Matching Network](https://pmc.ncbi.nlm.nih.gov/articles/PMC10532480/)
 This study aimed to develop a video-based approach to analyze the performance of
@@ -505,10 +523,14 @@ The Quiske pod also allows for dynamic rowing on machines such as a Concept2 on
 * [Quiske knows dynamic too](https://www.rowingperformance.com/blog/quiske-coach-knows-dynamic-too)
 * [Making Sense of the Data](https://www.rowingperformance.com/blog/making-sense-of-the-data)
 * [Technique](https://www.rowingperformance.com/blog/three-steps-to-good-rowing-technique)
+  Chapter 4 Technique
 * [Drag](https://www.rowingperformance.com/blog/drag-factor)
+  Chapter 5.2.3 Handle Drag Factor HDF
 * [Rowing Style](https://www.rowingperformance.com/blog/got-style)
+  Chapter 4.1.5 Rowing Styles
 * [More Style](https://www.rowingperformance.com/blog/drill-into-style)
 * [Stroke timing](https://www.rowingperformance.com/blog/stroke-timing)
+  Chapter 4.1.6 ‘Transition point’ during the drive
 * [Rhythm](https://www.rowingperformance.com/blog/what-s-your-rhythm)
 * [Swing](https://www.rowingperformance.com/blog/how-s-your-swing)
 * [Android 13 app](https://play.google.com/store/apps/details?id=com.quiske.rowingperformance&hl=en_GB)