Testing Triumph-LS GPS+GLO+GAL+BDU in Canopy

Shawn Billings

Shawn Billings
I had some early technical difficulties with my attempt to test Adam's theory and went back to testing the same way I did yesterday. I continued to have some strange issue into the beginning of this new test. I started at 13:48 and collected point 1, which took 1455 seconds. Which seemed a bit too long, but I figured it would eventually sort itself out and left it. I returned an hour later and found it still had not completed point 2. I poked around and managed to lock it up attempting to look at the satellite screen. At that point I forced a hard reset (powered it off and then on again). Once rebooted I started again at 15:39. Point 2 was the first point collected and required 3580 seconds (still way too long). Then point 3 and the subsequent points collected more as I would expect. Point 3 required 251 seconds. Averaging the times required for the 18 points I collected, including the hour for point 2 results in an average time per point of: 744 seconds or 12 minutes 24 seconds. Half the observations were five minutes or less. Nine of the 18 points post processed in DPOS correctly. There doesn't seem to be an obvious correlation to time on point and good post processed results. One point with only 181 seconds processed correctly, while one point with 2612 seconds did not process correctly. I'm sure that extremely long sets (perhaps > one hour) would prove to be more reliable than extremely short sets (perhaps < five minutes), but I can't make any real determination from this data.

For the environment, I would still submit that these results are very impressive. All RTK points collected in this test were good with no outliers and showed consistent accuracy to yesterday's data:

Average of 18 points:
N: 0.146 ft
E: 0.119 ft
U: 0.258 ft

Even with three very long observations (1455 seconds, 3580 seconds, and 2612 seconds) the average time per point was just a shade over 12 minutes. Taking these three out of the average and leaving the fifteen others would give an average of only 6 minutes 23 seconds!! Depending on the canopy you find yourself working in, you may find the addition of GAL and BDU to your base corrections to make a significant improvement to your production. If working in generally open conditions the addition may not represent a significant difference in production gains although I'm anxious to test how GAL and BDU will improve (if at all) the range of single baseline observations.

Nate The Surveyor

Well-Known Member
My thinking is that you don't have a Javad LS Plus. You've not upgraded. Therefore, the T3 upgrade, without the LS upgrade may affect this equation. The question is how much.

Shawn Billings

Shawn Billings
I can only speculate at present as I do not have access to a Triumph-LS Plus right now. I would guess that the performance improvement will be noticeably better in canopy over the current LS. I can say that the performance I'm seeing with the Triumph-LS basic version, with the Triumph-3 using GPS+GLO+GAL+BDU is significantly improved over the Triumph-LS with Triumph-2 using GPS+GLO only, as I believe these tests have demonstrated so far.

Shawn Billings

Shawn Billings
Today, I set up the Triumph-3 and Triumph-LS in the same location, this time transmitting only GPS and Glonass corrections, using the standard V6 GPS+GLO engines. The test ran for 6 hours. In that time I collected 14 points, for an average of 26 minutes per point. Using the same profile with GPS+GLO+GAL+BDU at the same time of day averaged about 16 minutes on day one and 13 minutes on day two. From this test it seems the new engines saved about 10 minutes per point in this particular location at this particular time of day. My hope is to set aside two full days with similar weather and test 24 hours with each, this way catching the highs and lows of satellite availability.

I have to say, I was impressed by the GPS + Glonass in this environment. I've run similar tests on this site with GPS+GLO with no collected points to show for it. The deciduous trees are still blooming today as spring arrives. I know my previous difficulties were in the height of summer, so the canopy was at least marginally worse the last time I did this. Also, no doubt the engines have improved in the years since I attempted to collect this point. Today's average of 14 points:

N: 0.103ft
E: 0.165ft
U: 0.487ft

very similar to previous results with multi-constellation.

The main point of these tests will hopefully demonstrate the time savings that multi-constellation RTK offers so that you can decide if the investment will pay for itself by working in more difficult places and getting results more quickly. At this point, our results would suggest that you might be able to save perhaps 40% of the time required for points in canopy. I don't know if these results can be linearized in that way, such that you think back to that point you sat on for an hour last year and can expect that today it would generally happen in 36 minutes instead.

So for those weighing this out, you might ask:
How many times per day/week/month/year do you run into a point that takes an excessive amount of time to observe?
How long do those observations take?
Multiply that by 40% (if these early results hold up) and multiply that by the field rate and see how many days/weeks/months/years it would take to make up the cost of investment.
One thing this math doesn't account for is opportunity costs. Maybe there were a couple of those points that took an hour and knocking an hour off the time it took to finish that job would have allowed you to complete the job without returning the next day or it allowed you to get finished and get started on the next project.

For those who are using a Triumph-1M, the cost to upgrade (from stock configuration) is currently $3000 to enable both Galileo and Beidou. For those with a Triumph-2, the cost will be a new base with the Galileo and Beidou options enabled. I would definitely recommend acquiring both Galileo and Beidou. I think only adding one would provide marginal benefits.

Only you can answer these sorts of questions. If I were working in the wide open, rarely struggling under canopy, I'd stay with GPS + Glonass. Hopefully these tests will give you some data that you can plug into your balance sheets to see if upgrading makes sense for you.

I'll share more data as I have time to acquire it. If anyone has any questions or would like to see more, feel free to ask.