Quick Here+ vs Reach vs Septentrio RTK

Hardware Pixhawk 2
1

Hi there

Running Pixhawk 2 (v3.5r6) and latest mission planner 1.48.

Just got the HERE+RTK set and thought I would do a highly scientific quick static test outside in non-ideal setting. Actually I’ve been using Reach (limited success) and have got a Septentrio AsteRx-m2 to demo.

I know we’re not talking apples vs apples here (Reach L1 and Here+ L1 can be apples and Septentrio L1/L2 is a banana)

Simple demo:

  1. Here+ Rover GPS connected to Pixhawk 2 connected to mission planner with RTK corrections from NTRIP server via MP
  2. Reach RTK unit on it’s own connected to wifi and same ntrip server
  3. Septentrio standalone unit connected to VRS/NTRIP via GPRS modem

Snapshot results
Here+ stayed RTK Float … with position and altitude drift of a few metres - 1 hour operation
Reach unit actually got and held a FIX (AR 999) - got fix after 10 mins
Septentrio got fix less than a 1 minute

Some snapshots attached. To be fair, I restarted the Reach unit and it never got a fix again. Same as Here+. Although I noticed up to 3m altitude drift from Here+ in RTK float. Also understand that a ground plane will help performance.

Screenshot_20170520-155444.png1080×1920 82.5 KB

Not quite sure what I was expecting but I guess I need to see if there is anything that can be tweaked in the HERE+ to improve ability to get a fix.

I’m a little clueless here, but it strikes me odd that the base station of Here+ and mission planner do not allow NTRIP corrections to the base in order to create a more accurate Survey In location? Perhaps I’m missing something??

I would be happy for relative positioning (i.e. rover in relation to base … don’t need exact coords) as long as it’s constant and accurate.

Might need to try in a better ‘sky view’ environment. BUT, I’m blown away how quickly the L1/L2 system locked in. But there is 8-10x price difference!

Reach does well sometimes, but seems to be a hit and miss scenario. Once you get a FIX … I tip toe around and tell everyone to keep quiet … just incase. Interesting to see that the altitude differenc between a FIX in REACH and a FIX in SEPTENTRIO is about 1.5m! I think I know which GPS altitude is correct :slight_smile:

Do the survey in coordinates need to be accurate at all if I’m only interested in relative positioning?

Appreciate any words of advice/wisdom. Whats everyone elses experience with HERE+

Cheers
Jason

2

Ublox recently had an update for Here+ to the M8P 1.30 firmware, which results in much easier fix result from my experience. You may find the instruction for update in the hex website download section.

3

Hi Jason,

I tested a lot of GNSS boards and receivers. The performance difference single-frequency and dual-frequcny GNSS/GPS is quite large.

What is your application by use GNSS RTK? Do you have interests in cost-effective L1 L2 GNSS RTK? Please drop me an email: quan.zhu@tersus-gnss.com

Regards,
Nick Zhu

4

Hey Nick, I’m already talking to you re precis boards. Will email again Monday.

Was really hoping a L1 system would be robust enough …

Thanks
Jason

5

Great, didn’t know about firmware upgrade. Are you always getting a fix?

6

Jason from SixArms? Aha, we met again here.

7

You have to put a ground plane below your reach of minimum 70mm.
If you don’t do that you will get poor results. It’s on reach and tallyswan antenna manual

1 Like
8

Do you have more information or news about reach and here+ rtk?

9

Quick question, how do you update the software, what cable do you use to connect the HERE +?.

10

Use the same cable from the base station, open you rover GPS, plug base USB cable into connector next to main connector. See instructions here
http://www.hex.aero/wp-content/uploads/2017/05/Here-RTK-GNSS-firmware-v1.3-update-instruction.pdf

1 Like
11

Thanks a lot. Document is all I needed.

12

Re: ground plane. I was under the impression HERE+ rover module has a sufficient ground plane in the enclosure. Is this correct?

We are using a ground plane on the ground unit.