Marco Polo M2P placement?

[Inspirephil]

We have done some testing of the Marco Polo Advanced RC Recovery Tag with submersion in water and have recorded the following results:

Loss at 6 inches freshwater depth vs free air: -24dB
Loss at 18 inches freshwater depth vs free air: -48dB
Additional loss per foot of freshwater: -24dB

To put this in perspective:

• Our system has a “link margin” (maximum end-to-end loss) of about 148 dB.
• For propagation near the ground we routinely see the signal drop off at about 10 dB for each doubling of the distance (not 6 dB as it would be in outer space).

The way this works out in air is that the signal loses is about 40dB in the first 3 meters (standard FCC test range distance), cutting the remaining link margin to 108dB. If the signal loss is 10dB for each doubling of the distance we can double the 3 meters 108/10 = 10.8 times before the signal gets too low to receive. 2^10.8 = 1783 so the max distance is 1783 x 9 feet (3 meters) = 16,047 feet or about 3 miles. If you increase the loss to just 11 dB for each doubling of the distance the range is reduced to 1.5 miles so it is very sensitive to the loss factor, wet vs dry ground, height off the ground, vegetation, etc. all make a big difference.

Using this model, which pretty closely predicts what we see in the field, we can plug in the loss numbers from the underwater tests to find the maximum distance of operation at various depths:

• At 6 inches depth I would expect the range to be: ~ 1/3 mile.
• At 18 inches depth about 400 feet.
• The approximate depth at which you would not be able to receive the signal, even if you were standing directly over the transmitter, would be about 6 feet. For what it’s worth, salt water would be worse and higher frequencies (i.e. 2.4GHz) would be worse.

You can read about the Marco Polo Advanced system here Advanced Single Drone Recovery System | Marco Polo | Tracking and Recovery Solutions

Tim Crabtree
President
Eureka Technology

Thanks for the information I appreciate you taking the time to help all of us who are depending on the Marco Polo tracking device for retrieving our expensive flying machines.
Anything that can help us finding them is a big plus in my book.
I also just purchased the DroneKeeper mini 2 as well to help me find my drones in the event of a disastrous loss of either my DJI Inspire 2 or M2P.
Once again thank you for this useful information.

 

[mwardncsu]

What advantages does the DroneKeeper 2 Mini give you over and above the Marco Polo tracking device? Is it something that I should look into? Never heard of it before but I am going to check it out and see what it’s all about. If you would please send me a link or any other information I would appreciate it very much.
Thanks for the tip.

The DroneKeeper is a basically a beeper - after a period of no movement it will go off with the audible beep - so if it’s in some thick grass or the like you can more quickly key in on it.

DroneKeeper mini2

 

[Inspirephil]

Water will highly attenuate many wireless signals..... so don't count on it in a submerged situation even if using the waterproof transponder.

Would you please post the information again about your findings on how water effects the signal from the Marco Polo tracking device. I accidentally deleted your post and I would like to see the information again so I can review it thoroughly.
Thanks, Inspirephil

 

[mwardncsu]

Would you please post the information again about your findings on how water effects the signal from the Marco Polo tracking device. I accidentally deleted your post and I would like to see the information again so I can review it thoroughly.
Thanks, Inspirephil

I think my response was fully inline with that from Tim. Water greatly impairs wireless signals in this frequency range is what I said - which is does.l as confirmed by Tim’s data.

 

[Inspirephil]

The DroneKeeper is a basically a beeper - after a period of no movement it will go off with the audible beep - so if it’s in some thick grass or the like you can more quickly key in on it.

DroneKeeper mini2

I checked out the DroneKeeper website and actually purchased one from them today. Along with the Marco Polo tracking system I will feel a lot more secure knowing I have done everything I can to find it if something happens. Thanks for steering me to the device.

 

[Tim Crabtree]

Would you please post the information again about your findings on how water effects the signal from the Marco Polo tracking device. I accidentally deleted your post and I would like to see the information again so I can review it thoroughly.
Thanks, Inspirephil

We have done some testing of the Marco Polo Advanced RC Recovery Tag with submersion in water and have recorded the following results:

Loss at 6 inches freshwater depth vs free air: -24dB
Loss at 18 inches freshwater depth vs free air: -48dB
Additional loss per foot of freshwater: -24dB

To put this in perspective:

• Our system has a “link margin” (maximum end-to-end loss) of about 148 dB.
• For propagation near the ground we routinely see the signal drop off at about 10 dB for each doubling of the distance (not 6 dB as it would be in outer space).

The way this works out in air is that the signal loses is about 40dB in the first 3 meters (standard FCC test range distance), cutting the remaining link margin to 108dB. If the signal loss is 10dB for each doubling of the distance we can double the 3 meters 108/10 = 10.8 times before the signal gets too low to receive. 2^10.8 = 1783 so the max distance is 1783 x 9 feet (3 meters) = 16,047 feet or about 3 miles. If you increase the loss to just 11 dB for each doubling of the distance the range is reduced to 1.5 miles so it is very sensitive to the loss factor, wet vs dry ground, height off the ground, vegetation, etc. all make a big difference.

Using this model, which pretty closely predicts what we see in the field, we can plug in the loss numbers from the underwater tests to find the maximum distance of operation at various depths:

• At 6 inches depth I would expect the range to be: ~ 1/3 mile.
• At 18 inches depth about 400 feet.
• The approximate depth at which you would not be able to receive the signal, even if you were standing directly over the transmitter, would be about 6 feet. For what it’s worth, salt water would be worse and higher frequencies (i.e. 2.4GHz) would be worse.

You can read about the Marco Polo Advanced system here Advanced Single Drone Recovery System | Marco Polo | Tracking and Recovery Solutions

Tim Crabtree
President
Eureka Technology

 

[BearMan54]

No apologies needed I understand what you were getting at. But being that the transmitter is waterproof it should allow me to retrieve my aircraft if it is under water. And that’s what the goal is, to retrieve it.
And IMHO direction of the antenna won’t cause any drag whatsoever.

Or if rains for a few days your transmitter will be nice & dry...... They will transmit for around 15 days....

 

[BearMan54]

We have done some testing of the Marco Polo Advanced RC Recovery Tag with submersion in water and have recorded the following results:

Loss at 6 inches freshwater depth vs free air: -24dB
Loss at 18 inches freshwater depth vs free air: -48dB
Additional loss per foot of freshwater: -24dB

To put this in perspective:

• Our system has a “link margin” (maximum end-to-end loss) of about 148 dB.
• For propagation near the ground we routinely see the signal drop off at about 10 dB for each doubling of the distance (not 6 dB as it would be in outer space).

The way this works out in air is that the signal loses is about 40dB in the first 3 meters (standard FCC test range distance), cutting the remaining link margin to 108dB. If the signal loss is 10dB for each doubling of the distance we can double the 3 meters 108/10 = 10.8 times before the signal gets too low to receive. 2^10.8 = 1783 so the max distance is 1783 x 9 feet (3 meters) = 16,047 feet or about 3 miles. If you increase the loss to just 11 dB for each doubling of the distance the range is reduced to 1.5 miles so it is very sensitive to the loss factor, wet vs dry ground, height off the ground, vegetation, etc. all make a big difference.

Using this model, which pretty closely predicts what we see in the field, we can plug in the loss numbers from the underwater tests to find the maximum distance of operation at various depths:

• At 6 inches depth I would expect the range to be: ~ 1/3 mile.
• At 18 inches depth about 400 feet.
• The approximate depth at which you would not be able to receive the signal, even if you were standing directly over the transmitter, would be about 6 feet. For what it’s worth, salt water would be worse and higher frequencies (i.e. 2.4GHz) would be worse.

You can read about the Marco Polo Advanced system here Advanced Single Drone Recovery System | Marco Polo | Tracking and Recovery Solutions

Tim Crabtree
President
Eureka Technology

My Marco Polo paid for itself the second time out....