Lightware SF11/C Laser Altimeter and [ultra] Bright Sun

Hi,

In December we had a great chance to test the M600 Pro system with a terrain following module in sunny Peru!

In general, SF11/C works perfectly. There was one annoying issue: under extremely bright sun over some surfaces it can miss readings for a long time. Fortunately, a solution was found quickly: during the trials we used improvised lens hood.

.. from short distance:

These altimeters are quite popular in the industry and among DIYers, so be warned if you use them to fly over very low altitudes.

Now we use modified holder for standard lens hood for Nicon lenses, but any similar ones should work as well.

I must say that Peru is a very interesting place in many ways. Especially the rich history of the Incas and earlier settlers, the ruins and other remains of their civilisation. As one of our hosts put it, “you can dig in any place in Peru and will probably unearth some ancient debris”. A lot of artefacts and skulls were lying just like that in the middle of the desert where we were testing our system..

Safe flights,

Alexey Dobrovolskiy

http://www.ugcs.com

As I still continue to receive the question about altimeters, I would like to write some conclusions.

We were fully dissatisfied by low-power laser range finders as altimeters for low-level flights. We tested different brands and makes, and all of them work approximately the same - very bad performance under the bright sun, over water, ice, in a light fog.

Laser altimeters can be used as an auxiliary sensor together, for example, for magnetometer, but we can't rely on them for flight management. Especially for low-level flights, where we can't use something like low-pass filters with big windows to ignore false readings - half of the second delay can lead to the crash.

So currently we use radar altimeters and supply laser devices only for special circumstances, like flights over the steppe in the dark at high altitude (because miniature radar altimeters have a shorter range).

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Alexey Dobrovolskiy November 12, 2020 at 1:59am

As I still continue to receive the question about altimeters, I would like to write some conclusions.

We were fully dissatisfied by low-power laser range finders as altimeters for low-level flights. We tested different brands and makes, and all of them work approximately the same - very bad performance under the bright sun, over water, ice, in a light fog.

Laser altimeters can be used as an auxiliary sensor together, for example, for magnetometer, but we can't rely on them for flight management. Especially for low-level flights, where we can't use something like low-pass filters with big windows to ignore false readings - half of the second delay can lead to the crash.

So currently we use radar altimeters and supply laser devices only for special circumstances, like flights over the steppe in the dark at high altitude (because miniature radar altimeters have a shorter range).
Alexey Dobrovolskiy March 21, 2019 at 6:00pm

Update.

Spent 2 more weeks in Peru. Lens hood helps partially, so we are looking for more powerful and robust laser altimeter.

Anybody has experience with WASP-200 LRF?

This reply was deleted.