GPS Accuracy - Equipment Suggestions

[Mike Brewer]

Good morning group!  I am new to Plant Collection Management.  As we speak our Garden is purchasing IrisBG.  I would love to know what everyone is using for GPS Mapping.  I'm interested in something that is more accurate than a handheld Garmin.  But I also don't want to break the bank!  (not sure that's possible) 

Thank you,

Mike Brewer

Plant Collections Manager

Magnolia Plantation & Gardens

[Jena Portanova]

Great question Mike,

Thank you for adding to the conversation.

I'm happy to share what I use at HBG. For us it was on hand when I started, and it is fairly accurate and somewhat budget friendly.  

Juniper Systems Geode GNS2 receiver.

They've since been updated with more bells and whistles. It is ~ 20 cm accuracy but given I don't have access to NTRIP and I am at the will of the overhead satellites on any given day, I find that the accuracy feels more like 50 cm to 1.5 m when I return to the location at a later date.  I have used a handheld Garmin (Colorado 300 I think) and it was ~3m accuracy, so this is an improvement.

Anyone else have that experience? or other recommendations?

-JP

[Carolyn Miller]

Hi Mike,

We have an EOS Arrow 200 and using Field Maps (ESRI) for my field collection. I have access to NTRIP, and I can get down to 20 cm accuracy. My only problem happens when I'm near buildings and the signal bounces around...at that instance, I simply drop points onto the map. 

Carolyn

Carolyn Jean Miller

Arboretum & Invasive Species Coordinator

Beal Botanical Garden & Campus Arboretum

Michigan State University 

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[Julie Rotramel]

Hi Mike,

We use a Trimble Catalyst DA2 receiver, which is subscription based, along with ArcGIS Field Maps. Subscriptions for the catalyst are priced based on your usage time frame and on level of accuracy. We have a yearly subscription, but there are hourly options if you expect your usage might vary widely over a year's time. 

Trimble provides correction services to Catalyst users, based on the level of accuracy you select in your subscription. Like others have mentioned, if we pay for 1 cm accuracy, we definitely don't always get that due to canopy coverage, buildings, satellite availability etc. I have seen as low as 2 cm under clear skies, and on average .5 to 1 meter under trees. 

Julie

GIS & Plant Records Specialist

Matthaei Botanical Gardens & Nichols Arboretum

University of Michigan

[Mike Brewer]

Thank you so much for the information.  

I've been investigating all of the suggestions here.  

I am leaning toward the Arrow 200.   

[Mike Brewer]

I will look into this...so far I'm leaning toward the Arrow 200.   

But this sounds like an option...especially the pay by usage.  

Thank you!  Mike B. 

[Kayla Flamm]

We've used:

- legacy Trimble R1 ($2500 when we bought it in 2015, now discontinued), claims up to 60cm accuracy but I'd say reliably roughly 1.5m accuracy 

- legacy Trimble R2 (the version we bought was about $12k in 2016, now discontinued), can get down to a few centimeters with RTK or NTRIP corrections 

- Trimble Catalyst DA2, subscription based (unit itself like $430ish, subscription price varies, here is a link to my local distributor for an idea of pricing https://catalyst.seilergeo.com/catalyst-wizard/ )

- EOS Arrow 100 (roughly $3,000), older model but I think still available, claims up to 60cm accuracy but I'd say reliably roughly 1m accuracy

- legacy Bad Elf GNSS Surveyor (was roughly $650, now discontinued), claims ~1m accuracy out of the box but I'd say reliably it's roughly 3m accuracy

- Bad Elf Flex Mini Extreme ($1500, but also comes in non-extreme version that is $500, difference is the Extreme can connect to a corrections network and can get sub-meter accuracy); the accuracy and reliability seems to be almost on par with the EOS Arrow 100 based on user experiences in the field.

Based on my and my colleague's experiences, the Bad Elf Flex Mini Extreme is a good balance of portability and reliability. I'm not going to use it for things like irrigation heads, but it's very good for mapping trees and larger objects, and great for field work. The legacy Trimble R1 was decent for its time, but no need to talk about its pros and cons since it's discontinued anyways! The EOS Arrow 100 is generally a good device, but the design is a little annoying: the antenna is separate fromt he unit itself, and they are connected via a cable. It DOES come with a stylish hat to place the antenna on the top of one's head.... But the newer Bad Elf Flex Mini Extreme seems to perform very similarly to the Arrow 100.

I still use the Trimble R2 for mapping utilities periodically, because I'm not a big fan of the subscription model of the Catalyst, even if the Catalyst really does perform better than the R2 especially in multi-pathing environments (think buildings, trees). Granted, lately most of my utility mapping has been sporadic, but once I ramp it up again I do intend to use the Catalyst.

Disclaimer: the above includes references to subjective experiences, so your mileage may vary.

[Jessica Brey]

Hi everyone, hope it is okay I am tagging on to this conversation. My initial question is the same as Mike's. Reading through your tech experiences was super helpful.

I have two additional that seem to relate:

We have some difficult terrain here at Wave Hill; I've heard hills can mess with the signal. We also are located on a cliff next to a river and across the river are some very flat cliffs that could reflect. Do these topographical features typically interfere with these devices? Our woods have a fairly thick canopy, and coworkers recommend not even bothering with devices due to this.

Also, what do folks use to get access to NTRI? A quick google search brought up this website, I wonder if they have non-profit rates...

This would be the first GPS device we are getting at Wave Hill in plant records. I've been using the antenna on an iPad which is not great.

Thank you!

[Jena Portanova]

These are great questions! I look forward to the discussion.

 

My first thought in trouble shooting your site is:  How well does cell phone reception work?  While phones are largely dependent on towers nearby, they could give you a glimpse into the interference\reception situation.

Forest canopy is a long-term hurdle so there is a lot published on the topic, but because of this there is a lot to wade through, meanwhile technology is ever improving.  This article is fairly recent and may be helpful The effects of nearby trees on the positional accuracy of GNSS receivers in a forest environment | PLOS ONE

I’m also sharing this esri proceedings could be insightful Collecting Quality GPS Data in a Canopy Environment

 

Jena Portanova

PLANT RECORDS MANAGER | TIPs Communication Liaison – APGA

 

Houston Botanic Garden

 

je...@hbg.org

713.715.9675 ext.143

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[Scott LaGreca]

Hi All

I'm at Duke Gardens and new to plant collections management. We are switching to IrisBG within the next year and I'm excited to use their Web Explorer capability. Towards that end I am following this conversation about equipment suggestions with great interest. I want to buy something like a Bad-Elf or an EOS Arrow device.

Two questions from me:

1. Do any of these purchases require some sort of maintenance plan/subscription, like $10-$20 per month? I don't know why they would, but my colleagues have asked me about this. It seems to me that if we were talking about Mi-Fi hotspots, that would require e.g. a monthly payment plan. But these GNSS devices wouldn't need that (would they)?

Mike Brewer, what equipment did you decide to purchase, and are you happy with it?

Thanks and best wishes,

Scott LaGreca

Paul J. Kramer Plant Collections Manager

Sarah P. Duke Gardens

Duke University