Trimble AT360 Activetrack target

From what I've been told, this is actually better for vertical measurement. gschrock has seen this in action. Please, post your results; I am very curious.

How does the price compare to the old Active 360°?
Chr.

I saw a prototype at Dimensions, it looked really slick. Unfortunately I'm a little hazy on any details as that was five months ago, but I remember being impressed with it.

I am very interested to see how your tests turn out

About £1500 GBP I think. My distributor only has 2, and I don't know if either are for sale yet.
The MT1000 sells at £1890.

Will be setting up some tribrachs to test next week I think.

Will compare to MT1000 (active and passive modes) and also to the trimble traverse prism (-35.0 constant).

Also, it can double as a disco ball for the field "party". 😉

First impressions -

1) The battery is under a twist off cap. About 1/6 turn to release it. Unfortunately the male 5/8" connector on top is also mounted to this. So if you are using a GNSS receiver or pole attached to the top then a twist would cause the battery compartment to open. Will need duck tape in this situation!

2) It doesn't fit into the polystyrene void in the S6 case. This would need some modification with a knife.

3) Doesn't feel as light as I imagined. Actual weights (with battery) MT1000 880g, AT360 630g.

Do you know what the maximum "allowed" vertical angle sighting is?

no instruction manual came with it

I haven't used one yet, but was talking to a Trimble dealer about one the other day.

He mentioned a couple of downsides.

Since it's not an actual prism the gun shoots it in DR mode. So if a car, tree branch or whatever gets in the way during the shot you get a bad shot just like any other reflectorless shot. (Did you notice any issues with this squowse?)

He also said it is not recommended for integrated surveying. The cap is a lightweight plastic and isn't strong enough to support a rover mounted on top.

If you are looking to get rid of your MT1000, I am looking to buy a pair of them second hand.

That sounds a bit unfortunate, as the accuracy specs when tracking in DR mode are 10mm as opposed to 5mm on a prism on an S3.

If so that would also imply that the range that you could work robotically would be limited by the range of the laser, not the radio, I don't think the range in DR mode to reflective foil exceeds 500m

I can confirm that it measures in prism mode, not DR.

Integrated surveying is possible (otherwise the thread would not be on the top) but I think a modification would be recommended to secure the top part of the target from "quick releasing",

I have finally downloaded the test measurements.
I set up 2 targets, 1 at head height and 1 at about 1.0m height.
I setup the instrument approx 23m away and measured the 1st target with a trimble round prism as a vertical reference. Then I measured the second prism with

a) Trimble round prism
b) AT360 prism in active mode
c) MT1000 multitrack prism in active mode
d) MT1000 multitrack prism in passive mode

3-4 sets on each, both faces.

I then brought the instrument closer to increase the vertical angle.
The various setups gave vertical angles of 91, 95, 100, 105, 100 and 116 degrees.

By the end the slope distance to the second target was only 1.5m. The variation of the distance especially to a value this low is not ideal but replicates a condition I encounter when rail surveying. There is often a physical limit to how far you can get away from the rail so as you come past the instrument the vertical angle becomes steep and the slope distance is small.

A summary of the results is shown below.

In synopsis

1) I would say that in comparison to the MT1000 in active mode the AT360 is much much more accurate on the verticals. Less than 1mm discrepancy apart from a face 1 only shot at 26 degrees of inclination. So as good as the passive prisms basically, apart from this one extreme condition.

2) Concerning horizontal discrepancies the AT360, similarly to the MT1000 in both modes, gets worse as the vertical angle is increased. Worst error was under 3mm and performed slightly better than the MT1000

A firmware update gives a bluetooth link to the controller and 3 new features -

a) eBubble (display only, no compensated point method). I have not been converted to using these. I find the effort of the calibration outweighs the benefits. If it was working in stakeout mode so that the correct position of the pole point was shown even while the pole was not plumb then I would be keen.

b) Target ID change on prism or controller synchronises via bluetooth. I have only ever needed to use target ID 1 so not immediately useful. The MT1000 target ID switch is also the on/off switch so it is quite possible to select the wrong ID inadvertently. This could not happen with the AT360. The on/off switch is separate to the target ID selector on the AT360 as well.

c) Battery level of the AT360 is shown on the controller. Useful - on the MT1000 you just get a ten minute warning if you happen to notice the light flashing. The battery level on the controller is slightly hidden. I am not sure if it comes to the fore when it gets low.

Click on graphs for bigger image

Was using this as a mini-prism today and realised there is no bubble on the top. (unlike MT1000 and the older trimble active target.)
I used a short pole with a bubble in the end, I suppose the ebubble is meant to replace this so I will have to look into the correct orientation of the prism so that the bubble on the screen reads true.

Thanks for the detailed review and testing. :good:

Squowse, the AT360 does indeed measure in DR mode and will not measure in prism mode. Since the foil is round, the beam is scattered too much to even get a return at 80ft in prism mode. Here in the NW, many surveyors are going back to the MT1000 because of false readings on branches, leaves and other interference. Trimble is also redesigning the top cover to address the locking/unlocking with integrated surveying, as well as the plastic housing cracking/breaking with a receiver attached.

I rekon they are probably best suited for machine control applications , were the glass gets all dirty and messy from dust and exhausts of the machines working , then the signal does not get returned as well. So go active reflective foil and then it won't be a problem.

I think I pass on buying a pair of these and go for the mt1000's

Thanks for the review though.