Considering VDSL2 tether


#1

After a bit of thinking about what else works at decent speed over a single wire pair, DSL came to mind.

Ethernet over VDSL2 isn't that new or uncommon, and can give >50Mbps at 500m cable lengths. So I figure at 50m through sea water (why don't spec sheets cover this scenario? ;-)) it shouldn't have a problem at all.

This does mean fitting a VDSL2 to ethernet bridge in to the OpenROV too, which is going to be rather tight.

So I'm going to try anyway and I'll let you know how it comes along. Steps (as I see them at the moment):

  1. Find the smallest VDSL2 CPE Bridge I can find that runs on <=12V DC (Netsys NV-202 or LevelOne VDS-0200 so far )
  2. Test it works over my tether on the bench
  3. Strip it down as small as possible (bye bye chassis and other sticky-outy-bits)
  4. Make sure it still runs in a small volume with no cooling air flow
  5. Measure if it runs cooler/lower current in CO or CPE mode if it's switchable
  6. Redesign the e-chassis so I can fit it all in the OpenROV, I see plenty of potential here
  7. Laser cutting with Ponoko (I don't have access to one, so 2 week turn arounds it is...)

Feel free to suggest other potential products or solutions. I'll keep you all updated on my progress.


#2

Hey Mike,

This sounds great. Interested to hear how tests go. The RasPi experimenters are also looking to redesign the echasis. Maybe there's some overlap.


Ponoko takes 2 weeks in NZ? That's where they are based!! Seems like a long turnaround time.

-David


#3

Here is a link to suppliers of VDSL2 chipsets. If you are handy with electronics, you can build a small circuit which would not take up much space (could be mounted on the cape).

http://forum.kitz.co.uk/index.php?topic=11470.0

Jim


#4

Yeah - 2 weeks is normal in my experience with a Prime membership.

6-8 days for cutting (with a Prime membership, up to 2 weeks without) then Ponoko use the slowest, most unreliable shipping method to send it up the country. I have seriously contemplated getting on a plane and flying down to Wellington to pick up items in the past.


#5

Today I had two LevelOne VDS-0200 arrive on my desk. They are a lot heavier than I expected, hopefully that is all in the chassis. I'll test they work as expected through the tether tonight then start stripping one down.


#6

An Update:

2. The pair of LevelOne VDS-0200 connected without issue over the 50m of tether I have.

3. The board is too big to fit in the current e-chassis, but it will fit in the tube so the e-chassis can be modified to fit it.

At the moment I'm putting this on hold. I'm currently going down the HomePlug approach as that will fit in the e-chassis without modification.


#7

Mike

Great to see this. I am going to test VDSL2 as well. I am looking at the following units. Any advice or tips would be appreciated. Have you measured the amp draw of your LevelOne units? Any reasons they may not perform well over 1000m in seawater?

CP TECH LevelOne VDS-0200 Ethernet Over VDSL2 Converter
http://www.shoplet.com/CP-TECH-LevelOne-VDS-0200-Ethernet-Over-VDSL2-Converter/g2BV6660/sgdv

VDSL2 Ethernet Bridge - NV-202
http://www.netsys-direct.com/product_p/nv-202.htm

StarTech.com 10/100 VDSL2 Ethernet Extender Kit over Single Pair Wire 1 km $270 2.8"W x 3.7"D x .9"H 3.2 oz
http://www.cdw.com/shop/products/StarTech.com-10-100-VDSL2-Ethernet-Extender-Kit-over-Single-Pair-Wire-1-km/1815988.aspx#TS

VC-201A Planet 10/100 Ethernet Extender over RJ-11 $260 PIN3 and 4 are used 3.9"W x 2.75D x 1.1"H http://www.neteon.net/products/compact-ethernet-extender/vc-201a.html



#8

I hope to use a single pair (loudspeaker cable) to power and communicate with my ROV and I'm curious about the VDSL route. What, if any, advantages does it offer over the PowerLAN/HompePlug system? Also, aren't telephone networks supposed to be twisted pair?


#9

Hi Lomax

If there are no unseen gotchas, then the main advantage is the distance and bandwidth. 10Mbs at 3000 ft. It was developed for twisted uses twisted pair because that what already exist. So companies can save lots of money tuning their existing phone lines between two buildings into network lines. It great for us, cause we can use that thin cable and reduce drag. I've ordered a couple of the StarTech units and will post the results.


Doug

SVSeeker.com


#10

Just an update. We tested Startech 10/100 VDSL Ethernet Extender Kit with Ixia QCheck using 100kByte samples and consistently ran up to 43.7Mbps over 3000 ft of 1 pair 24 awg wire. That should support 4 Full HD video cameras.