Garmin min. speed Proximity Alerts

 

Hello, I'm having a question regarding the proximity alert function of the Garmin Nuvi (and Oregon) models. I programmed custom points of interests for road culverts to warn public works mower operators of culverts that are not visible and to prevent damage to both equipment and infrastructure. I used the POI Loader Software and selected "Alert whenever you get close to a point" with an alert distance of 25m. Everything works fine unless the speed of the vehicle in the warning range is below approximately 5 km/h which happens frequently when mowing ditches. In that case no alert is triggered. Has anybody else experienced this problem? Is there a minimum speed required for the GPS to be able to pick up proximity alerts?

Thanks for your help!

There is no minimum speed

There is no minimum speed for proximity alerts. 700 feet (213 m) away from my house is a POI with a proximity alert. I sometimes get it while parking at a slow speed.

Other causes could be related to the actual POI location and the very short alert distance. Short alert distances do work, but they demand absolute accuracy in the POI location. You may have to make one POI exactly at one end of the culvert and another at the opposite end if that is also a mowed area.

Ordinary proximity alerts are simple. They work "along the road," while mowing is very roughly near the road. This could be a gray area for a proximity alert. If more accurate POIs or slightly increasing the alert distance do not help, there is another way to do it - TourGuide. This works by a radius around the POI and ignores "along the road." Look at the FAQ for this.

However, TourGuide may not be a cure-all because it also demands absolute accuracy in POI locations with the short alert distance.

dobs108 smile

My guess..

I would guess.. that the accuracy of the coordinates to determine the location of the culvert and the small radius (25m) of the alert are not being picked up by the GPS unit.

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Lives in Edmonton AB A volunteer driver for Drive Happiness.ca and now (since June 20 2021) uses a DS65 to find his clients.

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I would guess 25m is too short a distance, especially if the GPS accuracy isn't at its shortest. Terrain and atmospherics can reduce GPS accuracy. I suggest doubling or tripling the alert distance, and see how that works.

Btw, there's usually a way to see how accurate the GPS is. On mine, hold down on the GPS receiver bars, and it pops open a window showing satellites by number, position, strength, and overall accuracy. It fluctuates constantly.

Perhaps

It is speculation on my part, but perhaps the issue is that your points are a little too far from the road. I understand that some GPS software intended for vehicle use includes position calculation that uses a "snap-to" accuracy factor that adjusts the current position to show it on the nearest road.

If that is correct, the mower may be off the road but the GPS thinks that it is actually on the road, and you do not get a match.

- Tom -

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XXL540, GO LIVE 1535, GO 620

agree with -et-

I agree with -et-. There is little documentation about this but it has been discussed before. Increasing the alert distance would be the only way to remedy this.

dobs108 smile

Type of GPS

The type of GPS equipment you are using will also be a factor. If you have automotive GPS receivers mounted on your mowing equipment, the "snap to" function, which is designed for highway use, will likely work against you as ET and Dobs suggest. You would have better results using handheld GPS units which are more accurate at slow speeds. These receivers use more position averaging and rely less on "snap to" for accuracy.

The method used to determine the coordinates of your POI's (culvert locations) is also a factor. Maps, Google Earth as well as the GPS receiver itself all have different degrees of error which can compound. This becomes a problem when using a relatively small alert radius.

Unless you are using accurately surveyed highway maps, the best way to obtain your POI coordinates is with a good quality handheld receiver. Place the unit on the culvert and let it position average for a few minutes. I realize this is probably not practical for all locations though due to time constraints but it may help with certain POI's which consistently do not alert.

Yep ...

bdhsfz6 wrote:

You would have better results using handheld GPS units which are more accurate at slow speeds. These receivers use more position averaging and rely less on "snap to" for accuracy.

and more importantly 'snap to road' can be turned off ... unlike auto devices.

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Where there's a will ... there's a way ... DriveSmart51LMT-S, DriveSmart50LMT-D, Nuvi 2508LMT-D, 1490LMT, 1310, Montana 650T, Etrex 20

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The OP mentions the Oregon which is a handheld unit, but I agree that the the proximity distance mentioned is likely too small. I also wonder if the alert would be able to be heard over the noise of the machinery.

it's not winter yet!

How do I know?

MM hasn't put on her coat or hat yet.

--
Illiterate? Write for free help.

I didn't realize that my

I didn't realize that my question was already posted since it was my first post in this forum and it had to pass the spam check. I was very delighted when I saw all the comments. Thank you so much for sharing your thoughts and ideas. I didn't know about the "snap-to" issue of the vehicle GPS models and will look into the TourGuide function as well.

When I collected the culvert locations with a SkyPro XGPS (average accuracy was 5-10m) I stopped roughly halfway between both culvert ends in order to get one central point that would work for a proximity alert for both sides. I played with the alert distance many times and figured that 25m was an ideal distance when travelling between 5-10 km per hour. With a larger distance the alert was repeated several times which I was trying to avoid in order to minimize distraction.

I did a little experiment a couple weeks ago and programmed a GPS location close to my home (got the coordinates from satellite imagery) with an alert distance of 25m. I walked to that point with the Garmin Nuvi 44 in my hand and again with the Oregon 650. Both devices worked flawlessly when walking "fast" and didn't work when walking "slow".

I prefer the vehicle GPS over the handheld because of the larger screen and the capability of playing wave sound files as well as the higher volume and the mounting hardware that comes with the GPS. But what is most important to me is to find a solution that works.

I will repeat my little experiment with a larger alert distance and see what happens. Problem is I'm in Canada and it's -20 outside smile

Walking test

We have never heard of speed being a factor in proximity alerts.

(wait - brainstorm!) When you ran POI Loader, did the filename of the POI file you wrote have any numbers in it? I mean numbers in the filename itself, like mowing5.csv. If so, you have automatically created a speed file without intending to. For example, if the number 5 is anywhere in the filename, your speed file will give a proximity alert at 5 km/h and above, and no alert below 5 km/h!

Found on the internet - The preferred walking speed is the speed at which humans or animals choose to walk. Many people tend to walk at about 5.0 km/h; 3.1 mph. Although many people are capable of walking at speeds upwards of 9.0 km/h; 5.6 mph, especially for short distances, they typically choose not to.

dobs108 smile

Moving Too Slowly

thoabe wrote:

I did a little experiment a couple weeks ago and programmed a GPS location close to my home (got the coordinates from satellite imagery) with an alert distance of 25m. I walked to that point with the Garmin Nuvi 44 in my hand and again with the Oregon 650. Both devices worked flawlessly when walking "fast" and didn't work when walking "slow".

If you move too slowly with a handheld, most units loose the track you have been creating and begin to position average. You can get a visual representation of this if you zoom all the way in and watch the screen. Over time, a "starburst" pattern will display as each position refresh is plotted. Most consumer grade receivers need a succession of location points which are inside your alert circle before they will alert. This is done to avoid falsing. My Montana and Oregon units for example will sound an alert if you wait long enough. It sometimes takes a minute or more though. unfortunately, this defeats your intended purpose.

It's winter here

Box Car wrote:

How do I know?

MM hasn't put on her coat or hat yet.

She should need her coat by now. smile

--
Mary, Nuvi 2450, Garmin Viago, Honda Navigation, Nuvi 750 (gave to son)

Maybe she's in tahiti!

Box Car wrote:

It's Not Winter Yet!

How do I know?

MM hasn't put on her coat or hat yet.

A warm spot would be nice

dobs108 wrote:
Box Car wrote:

It's Not Winter Yet!

How do I know?

MM hasn't put on her coat or hat yet.

Maybe, a warm spot to go to would be nice this time of year.

--
Mary, Nuvi 2450, Garmin Viago, Honda Navigation, Nuvi 750 (gave to son)

I learned a thing or 2 on

I learned a thing or 2 on this one.

..

mgarledge wrote:
dobs108 wrote:
Box Car wrote:

It's Not Winter Yet!

How do I know?

MM hasn't put on her coat or hat yet.

Maybe, a warm spot to go to would be nice this time of year.

Ask you you shall receive. smile

A warm sunny spot somewhere?

Motorcycle Mama wrote:
mgarledge wrote:
dobs108 wrote:
Box Car wrote:

It's Not Winter Yet!

How do I know?

MM hasn't put on her coat or hat yet.

Maybe, a warm spot to go to would be nice this time of year.

Ask you you shall receive. smile

Are you toasting in the sun somewhere.
Must be nice somewhere. We talk about going somewhere warm, but talk is all we seem to do lately.

--
Mary, Nuvi 2450, Garmin Viago, Honda Navigation, Nuvi 750 (gave to son)