Zephyr heart rate data in gpx file

Hi

I use a Zephyr HxM heart rate monitor and when I look at the data in the exported gpx file, I noticed that the heart rate is recorded or updated every 3 or more seconds most of the time. E.G. HR is 147 for T11:58:27, T11:58:28, T11:58:29. See below.

Code:

<trkpt lat="37.21848" lon="-8.724013333333332">
<ele>72.0256</ele>
<time>2012-02-26T11:58:27Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>147</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.21835333333333" lon="-8.72402">
<ele>70.992195</ele>
<time>2012-02-26T11:58:28Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>147</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.21823" lon="-8.724023333333333">
<ele>69.917145</ele>
<time>2012-02-26T11:58:29Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>147</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.21810666666667" lon="-8.724023333333333">
<ele>68.83586</ele>
<time>2012-02-26T11:58:30Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>146</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.21798333333334" lon="-8.724026666666667">
<ele>67.774895</ele>
<time>2012-02-26T11:58:31Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>146</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.21786" lon="-8.724028333333333">
<ele>66.67917</ele>
<time>2012-02-26T11:58:32Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>146</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.21773833333333" lon="-8.724013333333332">
<ele>65.607376</ele>
<time>2012-02-26T11:58:33Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>144</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.217616666666665" lon="-8.723993333333333">
<ele>64.553535</ele>
<time>2012-02-26T11:58:34Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>144</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.217495" lon="-8.723973333333333">
<ele>63.53815</ele>
<time>2012-02-26T11:58:35Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>144</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>

Here it recorded and updated only every 6-7 seconds.

Code:

<trkpt lat="37.213971666666666" lon="-8.72241">
<ele>43.812634</ele>
<time>2012-02-26T11:59:13Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>143</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.213928333333335" lon="-8.722376666666666">
<ele>44.032475</ele>
<time>2012-02-26T11:59:14Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>143</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.213881666666666" lon="-8.722346666666667">
<ele>44.372356</ele>
<time>2012-02-26T11:59:15Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>143</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.213835" lon="-8.722316666666668">
<ele>44.702267</ele>
<time>2012-02-26T11:59:16Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>143</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.213784999999994" lon="-8.722285">
<ele>45.0247</ele>
<time>2012-02-26T11:59:17Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>143</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.21373499999999" lon="-8.722255">
<ele>45.416527</ele>
<time>2012-02-26T11:59:18Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>143</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.21368666666666" lon="-8.722226666666668">
<ele>45.835392</ele>
<time>2012-02-26T11:59:19Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>143</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.213638333333336" lon="-8.722201666666665">
<ele>46.249546</ele>
<time>2012-02-26T11:59:20Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>143</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.213591666666666" lon="-8.722176666666666">
<ele>46.53516</ele>
<time>2012-02-26T11:59:21Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>142</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.213544999999996" lon="-8.722151666666667">
<ele>46.84937</ele>
<time>2012-02-26T11:59:22Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>142</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.213494999999995" lon="-8.722131666666668">
<ele>47.185028</ele>
<time>2012-02-26T11:59:23Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>142</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.213445" lon="-8.722109999999999">
<ele>47.51177</ele>
<time>2012-02-26T11:59:24Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>142</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.213396666666675" lon="-8.722086666666666">
<ele>47.88183</ele>
<time>2012-02-26T11:59:25Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>142</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>
<trkpt lat="37.21334833333333" lon="-8.722061666666667">
<ele>48.309372</ele>
<time>2012-02-26T11:59:26Z</time>
<extensions><gpxtpx:TrackPointExtension><gpxtpx:hr>142</gpxtpx:hr></gpxtpx:TrackPointExtension></extensions></trkpt>

The Zephyr HRM is supposed to poll and send the HR every second so does Oruxmaps only read the HR every 3 or so seconds or is it something else? I use a Samsung Galaxy S2 with a external BT GPS so it's a powerful phone so I don't think it a processor power issue.

Can any other Zephyr HRM users (Uli?) check and comment whether their HRM data is similar in the exported gpx file. Is this normal behavior?

I apologise for bumping this but can any Zephyr HRM users confirm whether they too are getting slow updates for their heart rates with Oruxmaps.

cyberdude wrote:I apologise for bumping this but can any Zephyr HRM users confirm whether they too are getting slow updates for their heart rates with Oruxmaps.

Hi,

Sorry for the delay.

OruxMaps reads the heart rate monitor every two seconds, and joins each point of gps (whose frecuency depends on GPS settings) with the next heart rate reading.

I think it is a reasonable measure, the change in pulse rate during exercise should not be too high. Think of your SGII is one of the most powerful android devices, there are still many androids to 500Mhz...

But I will add an option in the future, to set this parameter.

orux

Sorry for the delay but I was in hospital for a fortnight.
In my HTC DHD the heart rate is recorded like this:

85 2012-03-11T12:45:12Z
85 2012-03-11T12:45:15Z
85 2012-03-11T12:45:17Z
86 2012-03-11T12:45:20Z
88 2012-03-11T12:45:22Z
89 2012-03-11T12:45:25Z
89 2012-03-11T12:45:28Z
87 2012-03-11T12:45:31Z
87 2012-03-11T12:45:34Z
87 2012-03-11T12:45:36Z
87 2012-03-11T12:45:39Z
86 2012-03-11T12:45:42Z
84 2012-03-11T12:45:45Z
84 2012-03-11T12:45:48Z
85 2012-03-11T12:45:51Z
87 2012-03-11T12:45:54Z
87 2012-03-11T12:45:56Z
87 2012-03-11T12:45:59Z
87 2012-03-11T12:46:02Z
87 2012-03-11T12:46:05Z
88 2012-03-11T12:46:09Z
87 2012-03-11T12:46:11Z
87 2012-03-11T12:46:13Z
86 2012-03-11T12:46:16Z
87 2012-03-11T12:46:19Z
89 2012-03-11T12:46:22Z
90 2012-03-11T12:46:25Z
91 2012-03-11T12:46:28Z
90 2012-03-11T12:46:31Z
90 2012-03-11T12:46:33Z
92 2012-03-11T12:46:36Z
93 2012-03-11T12:46:39Z
94 2012-03-11T12:46:42Z
95 2012-03-11T12:46:45Z
95 2012-03-11T12:46:48Z
96 2012-03-11T12:46:51Z
97 2012-03-11T12:46:53Z
98 2012-03-11T12:46:56Z
99 2012-03-11T12:46:59Z
99 2012-03-11T12:47:02Z
98 2012-03-11T12:47:05Z
99 2012-03-11T12:47:08Z
99 2012-03-11T12:47:11Z
99 2012-03-11T12:47:13Z
98 2012-03-11T12:47:16Z
97 2012-03-11T12:47:19Z
98 2012-03-11T12:47:22Z
99 2012-03-11T12:47:25Z

That looks like every 3 seconds?
Uli

Thanks Uli. Yes it looks like every three seconds. I wonder what prevents it from being recorded every 2 seconds as it's programmed to. In some of my tracklogs I noticed that at some points the HR is note updated for 6-7 seconds which doesn't sound long but when under extreme exertion and you HR goes over the max you want to know asap. I wonder if it's a limitation of the hardware, i.e. the BT communications with the phone etc. I have my GPS frequency set to record "always". Maybe that it causing too much load. I'll try set it to every 1 or 2 seconds and see if that helps.

I wish you a speedy recovery.

cyberdude wrote:Thanks Uli. Yes it looks like every three seconds. I wonder what prevents it from being recorded every 2 seconds as it's programmed to. In some of my tracklogs I noticed that at some points the HR is note updated for 6-7 seconds which doesn't sound long but when under extreme exertion and you HR goes over the max you want to know asap. I wonder if it's a limitation of the hardware, i.e. the BT communications with the phone etc. I have my GPS frequency set to record "always". Maybe that it causing too much load. I'll try set it to every 1 or 2 seconds and see if that helps.

I wish you a speedy recovery.

Do not worry;

Added a new 'setting':

<string name="pref_hxm_mintime_sum">Seconds between each HRM measurement (zero maximum rate)</string>

orux

Thanks orux. I look forward to that being released.

Curious if export to csv might ever get added? Or perhaps even a special export designed for reading the HR data inline with GPS position. If so, a general suggestion around this might be to keep previous GPS point repeating for each HR data point (as as option?) so that you get consistent data lines in the export while keeping the smooth nature of the gps track (min change to record). Anyway, something like this would be useful to at least myself for data analysis.

e.g.

trkpt,ele,time,hr
lat="0.00000000" lon="-0.00000000",0.0,2013-01-16T00:19:34Z,70
lat="0.00000000" lon="-0.00000000",0.0,2013-01-16T00:20:08Z,97
lat="0.00000000" lon="-0.00000000",0.0,2013-01-16T00:20:12Z,99
lat="0.00000000" lon="-0.00000000",0.0,2013-01-16T00:20:22Z,98
lat="0.00000000" lon="-0.00000000",0.0,2013-01-16T01:07:24Z,123

I would also like to find a way to just parse the existing formated gpx file, but it seems pretty unwieldy. I am able to use the HR data to some extent, but the mixture of the orux extension versus the trkpt extension is pretty hard to work through when doing raw data analysis. I am looking into using sed/awk in some combination to rip out the data and make it readable, but I'm not having all that much luck due to the mixture of extensions.

So... I found a way to parse the gpx file (since it has all the data in it regardless). I think I'm asking too much here. I was able to read the gpx track data just fine and the orux extensions at the end is readable as a delimited text (space) so really I have all the data I need and with further looking the extensions at the end for orux bpm has all the hr data recorded for the entire workout. Observation helps... lol Anyway, I was going to buy sportstracks, but found a pretty darn good open source sportstracker (http://www.saring.de/sportstracker/) written in java which reads orux gpx exports just fine with hr data. The orux extension data doesn't work right, but I can parse that data separately which is fine since I run it through a lot more math than sportstracker does.