Robotic lawnmower interference?

[mekhall]

Are there any measurements I can do to see how large and what kind of interference my Husqvarna mower produces? I have a cheapish oscilloscope and a nice multimeter...

Hook your scope up to the output of the amplifier board, then try different positions for the antennae till you minimise the signal from the lawnmower.
The lawnmower signal should show up very easily on your scope.
If you don't have a Blitzortung system yet then just build a loop antennae and connect that to the scope set to its most sensitive input, you may get better results with a small signal diode in series with the loop, this should work close to the lawnmower system.
Ben.

Ok, that sounds interesting - I will build a loop antenna and connect it to the scope (as I do not yet have a Blitzortung system).

[BobW]

Hello,

I have a big problem.

Since my neigbour owns a Husqverna Automower, my station isn't useable anymore. I get Interference all the time!

I checked the internet and found out that the mower uses a magnetic field, inducted by a wire arround the lawn, not to get lost.

I have a question about these mowers. Has anyone figured out what specific frequency that the wire radiates on? It would seem that it might be possible to help the mower "get lost" by running a parallel wire to the neighbors and inducing a "slightly higher" on frequency signal into the "other" wire. Enough jumps of the boundary, and subsequent ending of mowing, and they might give up. Wouldn't want to do this with a dog containment fence, but if the lawn mower were to escape......

Here in the US, there are very few manufacturer's selling those, and Husqvarna's web site lists no dealers of theirs here.

If they did show up here, they'd have to get FCC authorization - which they haven't yet -

For you global guys, the FCC is a good place to get more information about things that are sold in the US, and internal pictures too. For example, put "kz3" in the grantee code box, and you get a bunch of info on dog containment fences made by one company that operate on 10.7 khz. That IS considered RF in the US.

[petterfs]

Station 2691:
This is an old thread, but yesterday at around 18:00 I took the Automower out of hibernation and placed it in the charging station. As I wanted to check the blitzortung system and it indicated that it had been in interference mode since around 18:00 yesterday. I have both 3x ferrite antennas and an E-field antenna placed approx 8 meters above ground.

It seems that I have to
a) design a relay switch on the fence wire
and/or
b) set the gain manually in the blitzortung station...

[mwaters]

Station 2691:
... yesterday at around 18:00 I took the Automower out of hibernation and placed it in the charging station. As I wanted to check the blitzortung system and it indicated that it had been in interference mode since around 18:00 yesterday.

Have you gone into the Settings and enabled Auto Amplitude Filter? That helps eliminate RFI from robotic lawn mowers.

[petterfs]

Station 2691:
... yesterday at around 18:00 I took the Automower out of hibernation and placed it in the charging station. As I wanted to check the blitzortung system and it indicated that it had been in interference mode since around 18:00 yesterday.

Have you gone into the Settings and enabled Auto Amplitude Filter? That helps eliminate RFI from robotic lawn mowers.

Yes, I tried that, but it did not help. Contacted Husquarna today, and got an answer that if ECO-mode is enabled in the Auotmower, the loop will bed powered off during charging.
Will test when I get home today.

[petterfs]

Result after a little testing:
1. Enable "Eco mode" under settings in the Automower.
2. Start mowing (or press start at set start next day). This seems to be when the setting for Eco mode is saved. 

With the settings "Automatic, Noise adaption, Amplitude filter" 
Signals are approx 800mV p-p with the Automower loop active (Eco mode off), while with eco mode on (the Auomower loop inactive), the signal (noise floor) is approx. 75mV p-p

Ideal fix: 
1. Install a relay/contactor to disconnect the loop in case a thunderstorm gets near
2. Install a relay/contactro to disconnect the power supply to the Automower
3. Log when the Automower starts to cut, automatically setting the blitzortung receiver to manual mode with a predefined set of settings. 
4. Return to automatic settings as soon as the Automower is finished cutting.
5. Integrate all of the above in the Loxone smart home 


Signal without Eco mode enabled: 
   

Signals WITH ECO mode enabled (or with the automower charging station disconnected from power supply):
   

[OH4GRM]

You can use IFTTT to trigger parking of Husqvarna Automower when it is raining. Then having ECO setting on it turns fencing lines off as it is parked.