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600m tether length with advanved bluerov2 package


(Kelsey) #1

Hi all has anyone tried using 600m or more tether with the fathom x boards and had a reliable connection?
I have a customer that requires that length of tether to fly a pipeline.
From what i have read it should work in theory but im just wondering if anyone has tried it?

Also if possible @rjehangir could you supply a single length of tether that long?

Regards

DemonRobots


(Rusty) #2

Hi Kelsey,

We haven’t tested that but we can definitely supply at 600m tether. We currently get the tether on 1000m spools.

This is something we could test out here. I’d like to do that at some point.

-Rusty


(Kelsey) #3

Hi rusty

That would be great if you could test that out for us.
If it worked on 1000m would be even better.

If you get a chance sometime soon could you try that for us please.

Thanks heaps.

Kelsey


(Luc) #4

Hi Kelsey and Rusty,

I recently made some tests with a simple telecom wire pair, 600m length.
( this one : http://www.alliedelec.com/rs-pro-411784/70791947/ )
The link was ok, with a continuous transfer rate of about 53Mbits/s ( tested with iperf )
I believe that with BR tether it would be about the same.

Hope this help…


(Rusty) #5

Luc,

Awesome! That’s very helpful. I’ve also seen the bitrate drop off a bit at longer lengths. I saw 80 Mbps at 100 meters and 60 Mbps at 300 meters.

-Rusty


(Luc) #6

Rusty,

Yes, the FathomX has nice performances !
I’m currently trying to qualify it for a tether length of 1000 to 1500m.
But there are precautions to take to make such tests

The cable must be unwound
( try to disconnect one of the wire when testing with a wound cable, you’ll see that the link will still work ! )

Performances are differents in air and in water.
With the above telecom pair, once immersed (in fresh water !), the maximum length fall down to 290m, with a bitrate around 24 Mbit/s
I’m sure that with a cable with an outer jacket ( like BR tether )result should be far better, but this was intentional to test this “worst case”.

It would be nice to have informations about attenuation vs frequency for the BR tether.
Rusty, do you have such a graph ?

Luc.


(Rusty) #7

Hi Luc,

Very interesting. I’m curious to try with the jacketed tether. We don’t have a plot of attenuation vs frequency but that would be useful.

-Rusty


(Rusty) #8

Hi all,

Just for reference, I performed a bandwidth test with 1000m of tether. The tether was wound on a spool and in air during this test.

The maximum bandwidth dropped to about 28 Mbps. That’s plenty for video and the connection remained clear. There was no additional latency on the video stream.

I do think the results could change if the tether was unspooled and/or underwater, so these results should be taken with caution for now.

-Rusty


(ocenaman) #9

hi,Luc & everyone
How much can the Fathom X transfer when using 1000m tether?
20Mbps@1000m is OK?

@luc-rossi
@DemonRobots


(Luc) #10

Hi Oceanman,

unable to reply, i’ve not 1000m of tether at this time !
I did some bandwidth test with 150m ( in air ), but i need to make the same tests in water to check for the differences.
I’ll post the results as soon as i have enough time to perform this test !

Luc.


(ocenaman) #11

OK,Thank you very much
I guess that It also depends on ,maybe,the quality of cable


(achat) #12

Hi Luc,

Any new about your testing over long distance cable?


(Luc) #13

Hi,
sorry, I haven’t tested more than 300m of BR tether yet !
But the good news is that the bandwidth is about the same in air and in water!

I also tested 300m of BR slim tether in water and found about the same performances that with 4 pairs BR tether
( about 70Mb/s )