Error in Collector, Bad Elf Pro, iPhone 6s, iPadMini: "Estimated Accuracy- Your receiver is not sending accuracy information. Location accuracy of your current receiver will be estimated."

1574
9
08-16-2018 08:27 PM
DevonOesterling
New Contributor II

How do I resolve this error message in Collector? I have tried adjusting the settings in Bad Elf app and Collector with no luck yet. Any help would be much appreciated! Thanks.

Error message in Collector

0 Kudos
9 Replies
Kylie
by Esri Regular Contributor
Esri Regular Contributor

Hi Devon -- are you looking for information about what that message means, or why the display name for your receiver is different than you expect in Collector?

For the message, it means Collector isn't receiving a GST sentence in the NMEA but is receiving a GSA sentence. In this scenario, Collector estimates accuracy using horizontal dilution of precision (HDOP) and vertical dilution of precision (VDOP). The estimated horizontal accuracy is calculated by multiplying HDOP by 4.7, and the estimated vertical accuracy is calculated by multiplying VDOP by 4.7.

For the display name, Collector displays the manufacturer and the serial number of the device. This is limited by the information that we have available to use to identify the device. I tested with a Bad Elf GPS Pro and I see the same thing you do -- that must be the manufacturer of the device.

DevonOesterling
New Contributor II

Information re the error only. I really appreciate your reply Kylie! I found the NMEA info you mentioned at the link the error message provides. However, what is the solution to the error? Is this error and the resulting accuracy in Collector standard for Bad Elf and Collector? If not, how do I resolve?

I am only able to get ~11' accuracy in Collector on my iPhone and iPad. This was with clear skies and no canopy or buildings. Most of the day was ~15-16'. Is this normal?

Seems basically the same as the iPhone's internal GPS with 4G.

I was hoping for ~8 feet accuracy in these conditions and ~10-12 under canopy. Is this realistic? 

The Bad Elf Pro is connecting fine to both devices through Bluetooth. I followed the Collector setup instructions on Bad Elf's website and this error resulted. 

Do I need to do additional setup in Collector or Bad Elf apps? Would setting up a Location Profile fix the error and increase my accuracy? I haven't reached out to Bad Elf yet and so far I've only found info about this error, rather than a solution. 

Thanks!

Devon

0 Kudos
Kylie
by Esri Regular Contributor
Esri Regular Contributor

Hi Devon -- The Bad Elf Pro doesn't support GST, so with that device, you will see that message. It's more an information message than an error: there isn't something you do to change it, other than using a different device.

As for the accuracy you are seeing, I'd say that's probably normal. If you look at the device specifications (Bad Elf GPS Pro) you'll see it offers up to 2.5m of accuracy. One thing to check is if you have a DGPS fix (as opposed to GPS). The device does support SBAS, which automatically corrects the positions you are getting. It depends if SBAS satellites are visible for you. Compared to the internal GPS of the phone, you'll get 2.5m accuracy more consistently with this device than the phone. The phone is often (with clear skies) about 5m accuracy. If you have questions about this I'd recommend reaching out to Bad Elf. 

A location profile is not going to change things for you: those are used if you have different coordinate systems between your positions and you map (for example, if there is a correction service). 

DevonOesterling
New Contributor II

Hi Kylie, you're right, I shouldn't have called this or treated this as an error in Collector. Good to know this is just a normal notification when pairing a Bad Elf with Collector on an iPhone. 

Collector is showing Fix Type as Differential GPS. Should Collector show DGPS or GPS? 

Like I mentioned, I was hoping for closer to 8' / 2.5m accuracy as opposed to the 11-16' I'm currently getting. Especially in wide open areas with clear skies. So far it's averaging 15'. It's great I can use my iPhone and iPad with no cell service in Collector to 11-15', but need additional accuracy with this device...if possible. 

Does anyone happen to know if it's possible, and if so, how, to improve the accuracy of my Bad Elf Pro and iPhone or iPad beyond 11' in open areas with clear skies?

I'll call Bad Elf as well. Thank you so much!

0 Kudos
Kylie
by Esri Regular Contributor
Esri Regular Contributor

Seeing DGPS is a good thing -- that means SBAS (corrections) are being used, which does improve your accuracy.

DevonOesterling
New Contributor II

Thanks again for all your help Kylie! Once I get out of  the field, I'll  call Bad Elf. Still can't get better than 11'. 

0 Kudos
DougBrowning
MVP Notable Contributor

Note in our testing we never got Bad Elf to be any better than a tablet gps.  Had an office toss a whole box of them.  

We found the key was to get something with a bigger antenna like an Arrow.  Esp in canopy.  Bad Elf antenna is too small.  Same thing with garmin glo.

These guys run actual field tests on them in all conditions and have a good report. 

http://www.resourcesupplyllc.com/comparison-results-field-tested-submeter-gnss/

We rented to do testing before buying a bunch.

DevonOesterling
New Contributor II

Thanks for your feedback Doug, I really appreciate it! I don't need sub-meter for most applications but was hoping for slightly better than 11' accuracy with the Bad Elf Pro. I understand now that the manufacturer of most GPS antennas advertise the most accurate readings for ideal conditions, not an average across multiple conditions.

I've already noticed some major inaccuracies in my shown location and GPS'd polygons using my Bad Elf Pro and iPhone/iPad in light to moderate canopy with moderate cloud cover. I'm usually under varying densities of canopy so I'll likely have to upgrade to one of the units in this article.

Does anyone have a particular make/model suggestion, based on their own experience, for a sub-meter bluetooth GPS antenna or a step below sub-meter, for using mostly under canopy w/ Collector? Something between super-high-end and the Bad Elf Pro?  

Great article, thanks for sharing. I'll look further into these bluetooth GPS antennas to use with Collector. 

Can you share your source for renting these types of bluetooth GPS antennas? Good to know that's an option! Wish I had known that before I bought my Bad Elf Pro. The Bad Elf Pro is accurate enough for most of my applications, under most conditions. But I definitely need something more accurate for certain uses. 

0 Kudos
DougBrowning
MVP Notable Contributor

The company that wrote the article rents them. 

We ended up getting nothing.  The rental guy liked the Arrows I think.  Just call them.  Great group.