What are the units for Garmin's GPX gpxtpx:speed?

Question

I have a Garmin Nüvi GPS and it's filled with XML records that look like this:

<trkpt lat="38.900207" lon="-77.008990">
<ele>11.67</ele><time>2013-06-11T04:04:49Z</time>
<extensions>
   <gpxtpx:TrackPointExtension><gpxtpx:speed>6.86</gpxtpx:speed> 
   <gpxtpx:course>271.06</gpxtpx:course>
   </gpxtpx:TrackPointExtension>
   </extensions></trkpt>

(line breaks added for legibility)

My question — what are the units for gpxtpx:speed ? I've examined all of the trackpoints for my GPS and the gpxtpx:speed never gets much above 30, and I KNOW that I'm going faster than 30MPH.

I've scanned the documentation and I can't find what the units are.

Answer 1

it is documented here: http://www8.garmin.com/xmlschemas/TrackPointExtensionv2.xsd.

<xsd:element name="speed" type="MetersPerSecond_t" minOccurs="0"/>

and type MetersPerSecond_t is defined as

<xsd:simpleType name="MetersPerSecond_t">
  <xsd:annotation>
    <xsd:documentation>
      This type contains a speed measured in meters per second.
    </xsd:documentation>
  </xsd:annotation>
  <xsd:restriction base="xsd:double"/>
</xsd:simpleType>

Answer 2

There are a few speeds that can be immediately tossed out:

30 ft/s = 20 mph < 30 mph
30 km/h = 19 mph < 30 mph
30 yd/s = 61 mph > 30 mph (not exactly a standard measurement)

The only other "common" speed I'd say is m/s, which works well:

30 m/s = 67 mph > 30 mph

If you can confirm that elevation is given in meters (it looks like it is for that particular point), that would be a nod towards m/s.