freeday Posted September 30, 2007 Share Posted September 30, 2007 and loses with the new firmware 39 percent difference !!!! after making a hike with some breaks gpsmap 60 csx 11,6km etrex vista hcx 8,36km Garmin updated the firmware a view days ago (firmware and gps firmware) But the result is still not good enough to use the odometer field. What do you think would be ok for the odometer difference 1% 2% 3% 5% 10% 20% 39% For me it should be unter 3%. Or is it better to send the VISTA HCX back to the dealer because waiting for one year of otimizing the firmware would be better. What difference would be OK for you? Quote Link to comment
zulutime Posted September 30, 2007 Share Posted September 30, 2007 Physics is a b!tch. Quote Link to comment
geoprincesss Posted September 30, 2007 Share Posted September 30, 2007 (edited) Just out of curiosity, how close did the HCX track log compare to the 60 odometer? Several have reported the track log is accurate. Edited September 30, 2007 by geoprincesss Quote Link to comment
+Miragee Posted September 30, 2007 Share Posted September 30, 2007 Hmmm . . . that's interesting. Last week I took a hike and it never dawned on me that the Trip Odometer was quite a bit less than the track recorded, but it was because I remember being surprised when I did a screenshot of the hike Profile. Now I wish I could remember what distance the GPSr recorded. FYI, I still have the original firmware on my HCx. Quote Link to comment
+TrailGators Posted September 30, 2007 Share Posted September 30, 2007 (edited) Hmmm . . . that's interesting. Last week I took a hike and it never dawned on me that the Trip Odometer was quite a bit less than the track recorded, but it was because I remember being surprised when I did a screenshot of the hike Profile. Now I wish I could remember what distance the GPSr recorded. FYI, I still have the original firmware on my HCx. GPSs will always be inaccurate on slopes because I believe that they only record the horizontal distance traveled and don't include the z-axis. However, that doesn't explain why the Vista HCX is "possibly" less accurate than the 60CSX. You might want to make the scale on the Y-axis the same as the X-axis to show the true angle that you hiked. That screenshot makes it look like you hiked up a 60 degree grade..... Edited September 30, 2007 by TrailGators Quote Link to comment
+StarDoc Posted October 1, 2007 Share Posted October 1, 2007 Hmmm . . . that's interesting. Last week I took a hike and it never dawned on me that the Trip Odometer was quite a bit less than the track recorded, but it was because I remember being surprised when I did a screenshot of the hike Profile. Now I wish I could remember what distance the GPSr recorded. FYI, I still have the original firmware on my HCx. GPSs will always be inaccurate on slopes because I believe that they only record the horizontal distance traveled and don't include the z-axis. However, that doesn't explain why the Vista HCX is "possibly" less accurate than the 60CSX. Nope, GPSs record in three dimensions. I think my Legend Cx will start doing it when it has a lock on four or more satellites. On the other hand, the z-axis tends to have the lowest accuracy, sometimes +/- 60 feet or more regardless of what the GPS is telling you for its accuracy. Quote Link to comment
+Chuy! Posted October 1, 2007 Share Posted October 1, 2007 (edited) Why is everyone assuming the 60CSx is accurate? Maybe it's off too. Edit: let me rephrase that: has the 60CSx been calibrated that it's being used as a benchmark for odometer accuracy? Edited October 1, 2007 by Chuy! Quote Link to comment
GeoBobC Posted October 1, 2007 Share Posted October 1, 2007 An interesting test would be to reset the odometer to 0, and then walk a known distance such as four laps around a high school track. Walk with the track log on. When you've covered a known distance, compare the trip odometer to the length of the saved track log to the actual distance. Quote Link to comment
freeday Posted October 1, 2007 Author Share Posted October 1, 2007 i now saved the track vom yesterday as a saved track on the gps ODOMETER: gpsmap 60 csx 11,6km etrex vista hcx 8,36km !!! Save track information on the gps unit: gpsmap 60 csx 11.83 km etrex vista hcx 11.27 km !!! The saves track-information is ok! The gpsmap-track seems to be a little bit to long because of wandering. And the hcx-Track is fine WHY IS STILL THE ODOMETER SO DIFFERENT !!! Quote Link to comment
+Prime Suspect Posted October 1, 2007 Share Posted October 1, 2007 Nope, GPSs record in three dimensions. I think my Legend Cx will start doing it when it has a lock on four or more satellites. On the other hand, the z-axis tends to have the lowest accuracy, sometimes +/- 60 feet or more regardless of what the GPS is telling you for its accuracy. No, distance traveled is measured along the geodetic ellipsoid. Altitude may be recorded in the tracklog, but it's not included in the calculation. At least, that's according to a Garmin tech. Quote Link to comment
CenTexDodger Posted October 1, 2007 Share Posted October 1, 2007 (edited) Nope, GPSs record in three dimensions. I think my Legend Cx will start doing it when it has a lock on four or more satellites. On the other hand, the z-axis tends to have the lowest accuracy, sometimes +/- 60 feet or more regardless of what the GPS is telling you for its accuracy. No, distance traveled is measured along the geodetic ellipsoid. Altitude may be recorded in the tracklog, but it's not included in the calculation. At least, that's according to a Garmin tech. That is my understanding as well. However, it is also my understanding that the difference in negligible on most grades that you can hike up (without climbing gear). ETA: The HCx models are new and it may take some work to get the bugs out. I am sure Garmin will get it fixed, as they have gotten all previous models fixed when users reported bugs. Edited October 1, 2007 by CenTexDodger Quote Link to comment
freeday Posted October 1, 2007 Author Share Posted October 1, 2007 The log of both units can be downloaded here: http://www.naviboard.de/vb/showthread.php?...8352#post158352 Please search for: garminbug.zip Quote Link to comment
BelchFire Posted October 1, 2007 Share Posted October 1, 2007 There is a lower limit of speed that signifies to the unit that you're not moving. That's how the unit differentiates between your normal movement and normal drift (which has got to be higher with the more accurate chipset; kind of a catch-22 for Garmin) and IIRC, that was the sticking point in the last version (2.2mph, I think) If you were dragging along at something truly pathetic, you might have spent a lot of time under the (newer, updated) minimum. What was your average speed? Quote Link to comment
freeday Posted October 1, 2007 Author Share Posted October 1, 2007 (edited) There is a lower limit of speed that signifies to the unit that you're not moving. That's how the unit differentiates between your normal movement and normal drift (which has got to be higher with the more accurate chipset; kind of a catch-22 for Garmin) and IIRC, that was the sticking point in the last version (2.2mph, I think) If you were dragging along at something truly pathetic, you might have spent a lot of time under the (newer, updated) minimum. What was your average speed? I have put it her: http://www.naviboard.de/vb/showthread.php?...8352#post158352 (Just look for garminbug.zip) I think the speed will be between 3-6 km/h. For me it is curious that as a saved track - the distance is fine. Edited October 2, 2007 by freeday Quote Link to comment
jmundinger Posted October 1, 2007 Share Posted October 1, 2007 I just ran a few errands on my bicycle and decided to track the ride with my older GPSr, a Legend C, and my Vista HCx. Admittedly, this was at bicycle speed, not a hiking pace. But, I did have to make the typical traffic stops. Plus, the errands involved a couple of stops along the way. The odometer for the Legend read 3.6 miles for the trip and, at the end, it was not acquiring satellite data - it had been working up to the time that I got on my bike after the last stop. The odometer on the Vista HCx read 5.6 miles. I downloaded the track log from the Vista - it was at 5.5 miles. By the way, the reason that I upgraded was to have a more sensitive receivers for those situations in which the Legend can't "see" the satellites. Based on my experience since installing the new firmware for the unit and the chipset - one short hike and one bike ride - I'd say that the unit is trip computer in my Vista HCx is performing within a range of tolerance that is reasonable to expect for a consumer/recreational grade GPSr. Quote Link to comment
freeday Posted October 1, 2007 Author Share Posted October 1, 2007 I just ran a few errands on my bicycle and decided to track the ride with my older GPSr, a Legend C, and my Vista HCx. Admittedly, this was at bicycle speed, not a hiking pace. But, I did have to make the typical traffic stops. Plus, the errands involved a couple of stops along the way. The odometer for the Legend read 3.6 miles for the trip and, at the end, it was not acquiring satellite data - it had been working up to the time that I got on my bike after the last stop. The odometer on the Vista HCx read 5.6 miles. I downloaded the track log from the Vista - it was at 5.5 miles. By the way, the reason that I upgraded was to have a more sensitive receivers for those situations in which the Legend can't "see" the satellites. Based on my experience since installing the new firmware for the unit and the chipset - one short hike and one bike ride - I'd say that the unit is trip computer in my Vista HCx is performing within a range of tolerance that is reasonable to expect for a consumer/recreational grade GPSr. Odometer: 8.36 km as a saved track: 11.27 km for me this is not withhin the range of tolerance Quote Link to comment
jmundinger Posted October 1, 2007 Share Posted October 1, 2007 Odometer: 8.36 km as a saved track: 11.27 km for me this is not withhin the range of tolerance I assume that you have installed both of the recent updates. I understand what you said about your experience. Based on the two times that I have worked with my Vista HCx since installing both updates, it appears that I am not having the issues with the odometer that I had with it prior to the updates, i.e. my experience is not the same as what you reported. Quote Link to comment
freeday Posted October 1, 2007 Author Share Posted October 1, 2007 Odometer: 8.36 km as a saved track: 11.27 km for me this is not withhin the range of tolerance I assume that you have installed both of the recent updates. I understand what you said about your experience. Based on the two times that I have worked with my Vista HCx since installing both updates, it appears that I am not having the issues with the odometer that I had with it prior to the updates, i.e. my experience is not the same as what you reported. It's up to date. Quote Link to comment
jmundinger Posted October 1, 2007 Share Posted October 1, 2007 Thanks. As I said, your experience with the update is different from mine. Quote Link to comment
+gpsblake Posted October 1, 2007 Share Posted October 1, 2007 (edited) Just something to check. Under Settings/Marine/Speed Filter - Make sure it is set to auto on both units. I've found if this is turned off, it will play havoc when walking slow or making several stops. Also make sure "lock to road" is turned off. Did my bike ride today using my old Etrex Yellow and my Etrex Cx.... 11.36 miles on the yellow, 11.39miles on the Cx...but it was on street conditions. The routing distance on Delorme Topo 6.0 said my route should have been 11.34 miles. Edited October 1, 2007 by gpsblake Quote Link to comment
Newb888 Posted October 1, 2007 Share Posted October 1, 2007 I think we need to step back a bit, like previously mentioned we need to determine which unit is more accurate. Maybe the new HCx is more accurate? Quote Link to comment
+oisact Posted October 1, 2007 Share Posted October 1, 2007 There are four measurements with two pieces of hardware: Odometer: gpsmap 60 csx 11,6km etrex vista hcx 8,36km Save track information on the gps unit: gpsmap 60 csx 11.83 km etrex vista hcx 11.27 km The fact that the Vista's odometer and its own track log vary that much shows that it has a major internal descrepency. When you consider that three of the four measurements are in agreement, then it is very likely that the Vista's odometer is wrong. Dan Quote Link to comment
BuckyBuck Posted October 1, 2007 Share Posted October 1, 2007 Just something to check. Under Settings/Marine/Speed Filter - Make sure it is set to auto on both units. I've found if this is turned off, it will play havoc when walking slow or making several stops. Also make sure "lock to road" is turned off. Did my bike ride today using my old Etrex Yellow and my Etrex Cx.... 11.36 miles on the yellow, 11.39miles on the Cx...but it was on street conditions. The routing distance on Delorme Topo 6.0 said my route should have been 11.34 miles. I can't find this Settings/Marine/Speed Filter toggle on my Vista HCx. The only settings that show up on it are Anchor Drag Alarm and Off Course Alarm. Am I missing something here? Quote Link to comment
Smac999 Posted October 1, 2007 Share Posted October 1, 2007 Just something to check. Under Settings/Marine/Speed Filter - Make sure it is set to auto on both units. I've found if this is turned off, it will play havoc when walking slow or making several stops. Also make sure "lock to road" is turned off. Did my bike ride today using my old Etrex Yellow and my Etrex Cx.... 11.36 miles on the yellow, 11.39miles on the Cx...but it was on street conditions. The routing distance on Delorme Topo 6.0 said my route should have been 11.34 miles. I can't find this Settings/Marine/Speed Filter toggle on my Vista HCx. The only settings that show up on it are Anchor Drag Alarm and Off Course Alarm. Am I missing something here? this setting is not on the new H's. the removal of which tells me garmin didn't know how to, or had problems dealing with the filtering right from the start and knew about it. Quote Link to comment
Smac999 Posted October 1, 2007 Share Posted October 1, 2007 (edited) I think we need to step back a bit, like previously mentioned we need to determine which unit is more accurate. Maybe the new HCx is more accurate? I can walk as far as you want. and make he HCX show 0 distance and 0 time moved. it simply doesn't count slow speed. when I walk a few hundred feet. and the trip meter says 0 feet and 0 time moved. it's pretty obvious it's wrong. the trip meter on the CX simply starts counting at a slower pace. Edited October 1, 2007 by Smac999 Quote Link to comment
+A.T.Hiker Posted October 2, 2007 Share Posted October 2, 2007 I think it depends on your signal strength. With a windshield mount, and a 60 mile ride, I have seen both car trip odometer and GPS trip odometer read 60.0 miles exactly. That is before I had new tires put on my car and then the car was consistently about a mile and a half behind the GPS, but is catching up again as the tires wear. Go figure. I have noticed erratic movements of the map screen and speed indicator on the 60Cx when under thick cover. Even though it maintains a strong signal lock, it can still through trip calculations off. At best it's a rough estimate. Same with your track log. Quote Link to comment
dogwalkers2 Posted October 2, 2007 Share Posted October 2, 2007 this setting is not on the new H's. the removal of which tells me garmin didn't know how to, or had problems dealing with the filtering right from the start and knew about it. And the aliens found at Roswell are working on it... Quote Link to comment
+Chuy! Posted October 2, 2007 Share Posted October 2, 2007 I think we need to step back a bit, like previously mentioned we need to determine which unit is more accurate. Maybe the new HCx is more accurate? I can walk as far as you want. and make he HCX show 0 distance and 0 time moved. it simply doesn't count slow speed. when I walk a few hundred feet. and the trip meter says 0 feet and 0 time moved. it's pretty obvious it's wrong. the trip meter on the CX simply starts counting at a slower pace. You HCx may need replacement; my Vista HCx seems to work well. I walked three blocks with my HCx in one hand and my Nuvi 660 in the other. The Nuvi 'won' with .18 miles; the HCx showed .17. I then drove to a cache: both showed 12.56 miles, although the HCx showed an average mph of 1 mph less than the Nuvi. Quote Link to comment
freeday Posted October 2, 2007 Author Share Posted October 2, 2007 It seems, that i did not say it clear enough: On higher speed it works fine. But on walking (Speed between 1-5 km/h) the odometer has great problems. Problems only on LOW speed under 3-5 km/h so reports of good odometer results by driving a car (or moving over 5 km/h under clear sky) do not really help to solve the problem in this thread Quote Link to comment
+Chuy! Posted October 3, 2007 Share Posted October 3, 2007 I think we need to step back a bit, like previously mentioned we need to determine which unit is more accurate. Maybe the new HCx is more accurate? I can walk as far as you want. and make he HCX show 0 distance and 0 time moved. it simply doesn't count slow speed. when I walk a few hundred feet. and the trip meter says 0 feet and 0 time moved. it's pretty obvious it's wrong. the trip meter on the CX simply starts counting at a slower pace. You HCx may need replacement; my Vista HCx seems to work well. I walked three blocks with my HCx in one hand and my Nuvi 660 in the other. The Nuvi 'won' with .18 miles; the HCx showed .17. I then drove to a cache: both showed 12.56 miles, although the HCx showed an average mph of 1 mph less than the Nuvi. Emphasis added. Quote Link to comment
freeday Posted October 3, 2007 Author Share Posted October 3, 2007 If you try a longer walk for 10 or more miles (not only 0.2 miles or less) you will see a difference. I also testet on the first day of the new firmware for only 1 mile and it was fine. Under clear sky it work fine - so you have to walk outside/outdoor and not only in a village/city. Seems that there are only a view people who use it for hiking-tours. Quote Link to comment
jmundinger Posted October 3, 2007 Share Posted October 3, 2007 I also testet on the first day of the new firmware for only 1 mile and it was fine. Prior to the firmware update, my Vista HCx would have been noticeably wrong after walking a mile. That degree of error seems to have been corrected. Under clear sky it work fine - so you have to walk outside/outdoor and not only in a village/city. Environmental issues will affect all of the consumer grade GPSr's, not just the new H series Garmins. And, the higher sensitivity receiver has reduced the influence of environmental issues on accuracy. Quote Link to comment
+Kabuthunk Posted October 3, 2007 Share Posted October 3, 2007 (edited) EDIT: Whup, remind me to read the entire topic next time. I read about half-way through and then posted about checking it by driving a car and comparing to the odometer... which is obviously higher than 3-5 km/h. Well... unless you ride the brake for a mile or two However... you could still use a car, go down a straight stretch of flat highway for about 5miles or so, mark off with a chalk-line or something where it shows exactly 5/10/whatever miles, and then walk it with both GPS's. I'd probably take that method, since if it's going dead straight with no terrain issues, then there's no excuse for one being off. EDIT #2: I just noticed in the original picture... why's the "moving time" and "stopping time" so horribly different between the two GPS's as well? I mean, unless you were crawling down the path, it should STILL register movement. When I'm walking with my Garmin 60Cx, it keeps saying I'm moving unless I'm going brutally stupid slow. Like... walking behind old person with a walker on a cellphone slow. The totals between the two systems are approximately the same, so why's the Etrex think you were at a stop for almost 4 hours, and the CSx think you were stopped for only 2 and a half? Which in retrospect makes this a LOT easier to come to a quick guestimate as to which one is inaccurate. Were you standing still for 2 and a half hours, or almost 4? Edited October 3, 2007 by Kabuthunk Quote Link to comment
jmundinger Posted October 3, 2007 Share Posted October 3, 2007 EDIT: Whup, remind me to read the entire topic next time. I read about half-way through and then posted about checking it by driving a car and comparing to the odometer... which is obviously higher than 3-5 km/h. Well... unless you ride the brake for a mile or two It was/is a speed related issue. With firmware version 2.30 (and, earlier,) the Trip Computer on the Vista HCx (and, presumably the other units in the new H series) did not function properly with a slow pace. If you look through the old threads on this issue, some people said that the threshold was 2.2 mph. Another poster suggested the threshold was 2.2 kph. With my unit, the problem occurred for sure below 1.5 mph and the threshold might have been variable between that speed and 1.9 mph. Since I installed the updated firmware, I have not experienced the problem. I have tested the unit on a 1 mile trek up a hill to retrieve a couple of caches; a 2 mile stroll in my neighborhood; and, a six-mile bike trip. Based on the way my GPSr performed prior to the update, I should have seen the problem on the two walks. But, in both cases, the odometer conformed with the track log. I hadn't tried the GPSr with the bike prior to the update, so I don't have a comparable experience. However, the trip did involve some stop and go because I was in traffic and I also stopped for a couple of errands along the way. Yet, the odometer and track log were consistent for that trip, too. Freeday has also updated his GPSr and it seems that his experience with the update has not been as positive as mine. Quote Link to comment
Ann_Brush Posted October 3, 2007 Share Posted October 3, 2007 I see no mention of location sample rate here. Consider the following: 2 GPS units: 1) One GPS is sampling (recording) a location to calculate distance every second, 2) The second GPS samples every 5 seconds. In one minute the 1st unit will have 59 line connections between the 60 locations it samples as you were walking - it then sums the distance recorded by each line connection, the second will have 11 line connections between the 12 location samples. The small side to side deviations you make as you are walking will be included in the distance covered in the first GPS but not the other. For example if you go left one second then right one second then left and right again for one second followed by one second forward the first GPS will record 5 seconds worth of total distance while the second will only record 1 second worth of total = forward distance. This problem is much worse at LOW speeds as the side to side deviations are proportionally much greater. Quote Link to comment
freeday Posted October 3, 2007 Author Share Posted October 3, 2007 (edited) ...Were you standing still for 2 and a half hours, or almost 4? Sorry i do not know. - We were walking and sitting in the grass. Made some stops at interesting places and some breaks for eating or drinking. - I did not look all the time on my gps because i enjoyed the nature with my wife But walking more than 11 km will take some time, so 2,5 hours of standing still will be more realistic. The vista tells me: 1:41 for more than 11km - that would be 6,6km/h or 4.1mp/h I took both systems side by side on my daypack. - So it was a very "practical" test - and not a test where i made a notice for every break. Both systems had the same sampling (recording). (Auto-more often) What i do not understand is the fact, that the "saved track odometer" is fine, but the odometer on the trip computer page is so different Why does Garmin not calculate the odometer from the saved-track-information - that would be fine. I put all date one more time in one thread: RESULTS-: gpsmap 60 csx etrex vista hcx ODOMETER-------: 11,6km 8,36km saved track dist: 11,83 11,27 mapsource dist---: 11,8 11,3 here are both .GPX on a different host: http://rapidshare.com/files/60029018/garminbug.zip.html Edited October 3, 2007 by freeday Quote Link to comment
freeday Posted October 3, 2007 Author Share Posted October 3, 2007 gpspassion has the same results - i am not alone with that bug link: http://www.gpspassion.com/forumsen/topic.a...amp;whichpage=5 Quote Link to comment
Ann_Brush Posted October 3, 2007 Share Posted October 3, 2007 Freeday's post CLEARLY shows a difference between the number of points collected by the 2 units. Red unit has 410 points while blue unit has 500. As I discussed above the unit with the higher number of points collected shows the longer distance. Quote Link to comment
freeday Posted October 3, 2007 Author Share Posted October 3, 2007 Freeday's post CLEARLY shows a difference between the number of points collected by the 2 units. Red unit has 410 points while blue unit has 500. As I discussed above the unit with the higher number of points collected shows the longer distance. This might be because of the wandering of the sirf-chip (gpsmap) but there exists still the question: why is the vista-odometer false Quote Link to comment
GeoBobC Posted October 4, 2007 Share Posted October 4, 2007 I notice there is a significant difference in "Moving Time" between the 60CSx and the Vista units in the screen shots. This suggests there is a different "minimum speed" under which the unit considers the user stationary. Quote Link to comment
+Volwrath Posted October 4, 2007 Share Posted October 4, 2007 Slightly OT. I thought the etrex case didnt fit, but it looks pretty good in that picture! Quote Link to comment
freeday Posted October 5, 2007 Author Share Posted October 5, 2007 Yesterday i informed Garmin that the odometer-bug still exists with the new firmware. Quote Link to comment
+Miragee Posted October 7, 2007 Share Posted October 7, 2007 I took a 7.1 mile hike today, according to the tracks downloaded from the GPSr to Mapsource. I didn't think to reset the Trip Meter until I started back. It recorded the distance as 2.63 miles. The tracks say the distance was three miles. I have not updated the firmware in my Vista HCx yet . . . Quote Link to comment
BuckyBuck Posted October 7, 2007 Share Posted October 7, 2007 I finally got around to comparing my odometer results post-firmware update to before update. Admittedly, not long distances and all over consistent elevations; but it's been hot, darn it. Here's what I did this morning: I walked around my 'hood at my average walking speed, with my GPS V in one hand, and my Vista HCx in the other. .............................. GPS V..........Vista HCx Distance..................0.85..............0.86 Avg. Speed..............2.7................2.8 Moving Time............17:19...........15:30 Less than one percent difference on distance. Not bad. Then I went to the high school track and walked around it. At a BuckyBuck walking speed: .............................. GPS V..........Vista HCx Distance..................0.25..............0.26 Avg. Speed..............2.7................2.7 Moving Time.......... 5:05...............5:03 Again, fairly consistent between the two units. Finally, I walked around the track at a plodding speed: ...............................GPS V..........Vista HCx Distance..................0.25..............0.22 Avg. Speed..............1.7...............1.5 Moving Time............8:40.............7:17 I'm assuming that the track dimensions didn't change between my first and second walk around it. So it looks to me like the GPS V is more accurate at slower speeds than the HCx, and that the HCx dropped about 9 percent in its ability to accurately measure distance. In another thread here, someone said that he or she was embarrassed by the few "griefers" complaining about this bug. Sorry, but I think that someone who purchases a hand-held GPS unit that's marketed for use "On the Trail" should have a reasonable expectation that the unit accurately registers speeds and distances at the speeds at which it is most often used. I don't especially care if my automotive, TTS GPS is inaccurate at 1.7 mph, because I usually drive at a higher speed than that. But I do have a reasonable expectation that my hand-held GPS should accurately record distances at normal hiking and walking speeds. Quote Link to comment
+user13371 Posted October 7, 2007 Share Posted October 7, 2007 (edited) From someone who has owned other than Garmins over the past 7 years: I have seen similar "odometer bugs" on every handheld Magellan and Lowrance I've ever used. The degree of error varied, but could always be summarized this way: - At lower speeds (walking, cycling) the odometer AND speedometer would underestimate. - At higher speeds (driving, flying) the readings were much more accurate. - Recorded track distances were quite accurate, in contrast to the "immediate" readings. My intuitive feeling is that immediate speed and odometer readings are based on the distance between position samples taken one second apart, and rounded down to the nearest unit -- dropping a few inches or centimetres from some number of metres or feet. At a lower speeds rounding down gives a larger proportional error, explaining why driving/flying numbers aren't off by as much. In contrast, track distances are calculated by summing the distances between all track points (with various "track smoothing" algorithms discarding bad or redundant points), giving a more accurate result. Starting from that theory, I believe speed/distance readings based on immediate position samples will always show these errors, though some clever math in the firmware might reduce them. A simple solution might be a user option/setting to report a "trip distance" based on the calculated length of the track being currently recorded, rather than immediate position samplings. Edited October 7, 2007 by lee_rimar Quote Link to comment
DonRolph Posted October 7, 2007 Share Posted October 7, 2007 Actually I have performed a series of tests on the GPSMAP 60CSx over knwn trail distances and compared with the DeLorme PN20. the DeLorme PN-20 typically is fairly close. The GPSMAP 60CSx is often 20+% low. I notice the same thing while driving: GPSMAP 60CSx reads a low odometer reading against my car odometer and against the PN-20 (lathough now the two GPS units are much closer). In short, I don't trusty my GPSMAP 60CSx odometer reading at all. Test from yesterday: PN-20: 7.83 miles GPSMAP 60CSx: 7.33 miles Actual distance is about 8 miles. Quote Link to comment
SiliconFiend Posted October 7, 2007 Share Posted October 7, 2007 In another thread here, someone said that he or she was embarrassed by the few "griefers" complaining about this bug. Sorry, but I think that someone who purchases a hand-held GPS unit that's marketed for use "On the Trail" should have a reasonable expectation that the unit accurately registers speeds and distances at the speeds at which it is most often used. I don't especially care if my automotive, TTS GPS is inaccurate at 1.7 mph, because I usually drive at a higher speed than that. But I do have a reasonable expectation that my hand-held GPS should accurately record distances at normal hiking and walking speeds. That would be me. I don't disagree that it's a bug and needs to be fixed. I'm embarrassed by the people that make such a huge stink about a really minor bug and imply that the entire unit isn't worth buying because the odometer doesn't tell you how long of a slug trail you left. Quote Link to comment
freeday Posted October 8, 2007 Author Share Posted October 8, 2007 In another thread here, someone said that he or she was embarrassed by the few "griefers" complaining about this bug. Sorry, but I think that someone who purchases a hand-held GPS unit that's marketed for use "On the Trail" should have a reasonable expectation that the unit accurately registers speeds and distances at the speeds at which it is most often used. I don't especially care if my automotive, TTS GPS is inaccurate at 1.7 mph, because I usually drive at a higher speed than that. But I do have a reasonable expectation that my hand-held GPS should accurately record distances at normal hiking and walking speeds. That would be me. I don't disagree that it's a bug and needs to be fixed. I'm embarrassed by the people that make such a huge stink about a really minor bug and imply that the entire unit isn't worth buying because the odometer doesn't tell you how long of a slug trail you left. A handheld gps which is designed for use "On the trail"... 39 percent difference ... minor bug.... @SiliconFiend: What is a bug for you if that is a really minor bug with 39 percent difference. Quote Link to comment
+GOT GPS? Posted October 8, 2007 Share Posted October 8, 2007 Actually I have performed a series of tests on the GPSMAP 60CSx over knwn trail distances and compared with the DeLorme PN20. the DeLorme PN-20 typically is fairly close. The GPSMAP 60CSx is often 20+% low. I notice the same thing while driving: GPSMAP 60CSx reads a low odometer reading against my car odometer and against the PN-20 (lathough now the two GPS units are much closer). In short, I don't trusty my GPSMAP 60CSx odometer reading at all. Test from yesterday: PN-20: 7.83 miles GPSMAP 60CSx: 7.33 miles Actual distance is about 8 miles. Seems like there might be a problem with your GPSMap60CSx, or that it is not being kept vertical I had the Map60Cx, but just bought a new Map60CSx back on Sept. 2nd, and the new GPS is right on, no problems with the odometer, but of course over the years I've learned to keep the GPS, as close to vertical as possible. The Trip time, Trip Odom, and Elevation seem to be right on. I have had problems with the 60 series when I held them lower in the hand, with the screen facing the sky. I find that I can get better results from a GPS that I can hold higher off the ground than an eTrex, where I hold the map 60CSx vertical with the GPS's antenna about shoulder height. Been getting good plots of hiking trails with the new 60CSx. The newer Highly sensitive GPS units are likely to receive dirty signals in times where the older GPS units would fail to keep a signal, so sometimes if the line-of-sight signals are blocked for some reason, the sensitive GPS will amplify lower quality signals, like reflected signals bounced off of hard surfaces. This is my best guess as to these issues. Quote Link to comment
SiliconFiend Posted October 8, 2007 Share Posted October 8, 2007 In another thread here, someone said that he or she was embarrassed by the few "griefers" complaining about this bug. Sorry, but I think that someone who purchases a hand-held GPS unit that's marketed for use "On the Trail" should have a reasonable expectation that the unit accurately registers speeds and distances at the speeds at which it is most often used. I don't especially care if my automotive, TTS GPS is inaccurate at 1.7 mph, because I usually drive at a higher speed than that. But I do have a reasonable expectation that my hand-held GPS should accurately record distances at normal hiking and walking speeds. That would be me. I don't disagree that it's a bug and needs to be fixed. I'm embarrassed by the people that make such a huge stink about a really minor bug and imply that the entire unit isn't worth buying because the odometer doesn't tell you how long of a slug trail you left. A handheld gps which is designed for use "On the trail"... 39 percent difference ... minor bug.... @SiliconFiend: What is a bug for you if that is a really minor bug with 39 percent difference. This bug is on the order of "the radio is stuck on the easy-listening station" as opposed to "the brakes failed". Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.