When using a Fishing Drone, you will quickly learn to identify and avoid potential hazards - your fishing rod, line, other fishermen, beachgoers, a flock of birds and more - but - there is also an invisible hazard that is equally important to identify and avoid.
Electromagnetic interference (EMI) can seriously affect your drone's navigation capacity. Especially if relying on features such as 'return to home'. EMI can come from any device or equipment with a power supply or the ability to emit its own signal. This ranges from powerlines to phones and other drones. What is the best way to keep your drone safe when flying near sources of signal interference?
What is electromagnetic interference?
EMI or radio frequency interference (RFI) is interference that affects the operation of an electrical device caused by electromagnetic fields. All electrical devices emit an electromagnetic field by the very action of current passing through a conductive material.
The magnitude of EMI varies according to the magnitude of the current powering the electrical device. Mobile devices that use Wi-Fi are less problematic than powerlines (think submarine cables under the water) or massive steel structures (power line towers).
The effects of EMI on drone operations are unpredictable. It can mess up your drone’s navigation systems by shifting its compass out of alignment. When flying near very large structures, EMI can severely degrade the quality of the GPS reception of your drone. It can also disrupt the communication between the drone and your controller. None of which you really want happening while it's 500 meters or so out to sea!
Tips on identifying areas with EMI issues
This is the challenging part. The EMI issues are essentially invisible - they can interfere with the drone, and you will not be able to tell.
We can, however, look at obvious causes of EMI issues and work to mitigate them by moving away from them. Some common causes will include:
- Caravans - apart from being large pieces of metal, Caravans also run electrical devices such as radios, microwaves and satelights. All of which can interfere with the drone compass and GPS function. Freedom camping spots are probably not the ideal location to launch from - you must move well away.
- Power lines - above and underground (or sea). Power lines are easy enough to see, but we also have a few submarine cables running underground and underwater. Flying a drone out over one of these may not work out well.
- Other drones and mobile phones - while your phone shouldn't be an issue, it's probably not best practice to try and calibrate your drone while holding your phone.
Certain areas in New Zealand are also known to have heavier than normal signal interference:
Orewa - for example - has a submarine cable running up alongside it, and, the military base is located at the tip of the peninsula. Papamoa - being busy as it is, has a lot of motorhomes, and other beach users that can interfere with drone operation.
Tips on flying your drone to minimise EMI issues
Calibrate away from potential issues
If your drone requires calibration - it's critical you do them before use. Drones have flight logs. And if it transpires you didn't complete all the required calibrations before having an issue - then you will likely find your drone won't be covered by warranty.
Dont Take off until you have a decent GPS signal
Your controller will tell you GPS strength. Don't take off (or even turn on the motors) until you see a signal of at least 8, and ideally 10. This will ensure that the unit has a solid 'return to home' GPS lock before taking off.
Don't rely on the 'Return to Home' feature
Return to home is a safety feature, not something that should be regularly utilised. Fly in either GPS mode or, ATTI mode - as they give you more drone control and less potential for issues.
Learn to fly in ATTI mode
Before you take your drone out over the water, one of the very first things you should do is learn to fly in ATTI mode. Short for 'Attitude Mode', ATTI is the mode that drones revert to when they lose GPS reception. Most drones have multiple flight modes. GPS Mode keeps the unit from drifting due to wind and environmental factors - but - requires a solid GPS signal to do so. ATTI mode will keep it at the same altitude, but not rely on the GPS - it's more 'manual'.
If you have never flown in ATTI mode before, you don't want it to be when you are trying to 'rescue' your drone!
Don't wait until your drone tells you it's about to run out of charge before you swap out batteries.
Many drones, upon dropping low enough, will automatically engage the 'Return to Home' feature. If you don't have a solid GPS signal when that happens, you might find it trying to return home, but getting into issues.
While we appreciate this isn't really preventative, it's a good idea. Despite all our best efforts, sometimes, things happen. Getting (and checking) your insurance sorted is a good idea. Some House and Contents will cover the drone, but not in use, and only if named on the policy. Understand what you are covered for, just in case.
It takes substantial practice, experience, and preparation to fly a drone safely. Loss of signal and GPS reception should be anticipated and integrated into operations planning.
If you experience any problems with your drone's controls while flying, it is important to know how to fly it home safely. Do not use the Return to Home (RTH) function, as this may not be able to resolve the issue. Instead, switch the flight mode to Attitude or Manual mode (not GPS mode) and fly the drone home manually. It is important to practice flying in Attitude mode, as the drone behaves differently in this mode than in GPS mode. In Attitude mode, the drone does not have the same horizontal position lock, so it may drift with the wind.