Vista Hcx Trip Computer Problem

[DonpK]

Owners of the eTrex Vista Hcx have reported inaccuracy problems with the data shown on the Trip Computer page which have been acknowledge by Garmin. See: http://forums.Groundspeak.com/GC/index.php?showtopic=179758 The problems seem to be related to the speed at which the receiver is moving, that is, sizable errors at walking speeds.

 

As a test I recorded four different tracklogs. Two the them in a car going about 15 mph and two of them on foot. In each of the pairs of tests, two different Track Log Setups were used: Record Method = Auto, Interval = Normal and Record Method = Time, Interval = 1 second.

 

The left image is for the car and the right image is on foot. In each the yellow track is in the Auto mode and the white track is in the Time mode.

 

 

The tracklogs taken on foot, shown on the right, are noticeably different, particularly at turns. The differences are even more noticeable when the Track Properties are looked at in MapSource. Keep in mind that in the foot test at no time did I stop moving. I tried to walk at a consistent 2-3mph.

 

Nevertheless the Track Properties in in MapSource show me moving 0 ft. and 0 mph for several track segments in a row followed by a a segment with a leg speed of 13mph where I covered a leg length of 312ft. in 0 seconds. This stop/start pattern continues throughout the tracklog.

 

Comments would be appreciated,

 

Don

[Lodogg2221]

See, this is partially the reason I didnt want to order the Vista HCx, but since I just did, hopefully Garmin will be on top of it...

Maybe Ill get lucky and get one of the more accurate ones some here seem to have...

[+travis71]

I edit all of my hikes in Mapsource, then view them in Google Earth. I do this in particular for hikes I do at a local state park, because I think their maps are s***ty, & I want to have a more accurate representation of them. I have mapped about half of the FSRs & trails in this smallish park & did my first hike with the Vista HCX last weekend. I did change the interval to more frequent, or w/e the "most" option would have been. I do hike at a pretty good clip, my hiking is for fitness as well as a hobby, & I dont like to lag much. From what I could tell of my overlay of the park on GE, the thing didnt deter much at all from the course I hiked... at least not to my eye. At the end of the hike the Vista said that I had trekked ~ 7.7 miles. I just went back & traced a rough overlay of my route & GE measured more around 8 miles. Now, whether the difference is due to the problem the unit has with the odometer, or if its because I didnt trace the EXACT trail (dot to dot) that the GPS recorded... well, I dunno. I think the error WILL effect a user, depending on their pace, but my first outing with the GPS seems to indicate that it will function better than my Legend, in regards to charting my trips & recording them online.

[+EraSeek]

I assume you took the very same route with the car and on foot. That is a big difference on the turns. Yet the turns seem to match for the most part on both the "auto" and the "time" mode on foot.

The fact that you have 0 speed and then a big jump suggest to me that what is going on with the HCX processing chip is much like what the 60cx (sirf) chips were doing early on, and that is static navigation. If it does get movement over a certain speed, or a good enough signal, it just kind of idles in place making you think it is navigating and then when you reach a certain distance from the last position it jumps.

I believe sirf disabled that in the geocaching GPS's, and I think I heard there was a fix for the etrex units that are in the Garmin updates. You might see if you have the latest update.

 

Other possibles are that you simply lost signal under tree cover while walking and it jumped when you re-aquired. It would not happen when driving because the speed filter would compensate for it at higher speeds and shorter period of time.