Seeking Advice on Single Pair Ethernet Connector for ROV

BotBlox Hardware
1

Hi everyone,

I am working with an ROV that requires a single pair Ethernet connector for data transmission over a 500m cable. The minimum required data rate is 500Mbps.

I’ve come across two potential modules but

  1. SPEBlox - Single Pair Ethernet Converter GigaBit to Single Pair - 1Gbps module, but it has only been tested with a 22-meter cable.
  2. SPEBlox-Long (10BASE-T1L) - 10Mbps, 1km range, single pair ethernet - 10Mbps module, which has been tested for up to 1km.

given my application, I’m trying to find a solution that balances both the cable length and required data rate. Has anyone come across a single pair Ethernet module that supports at least 500Mbps over 500 meters of cable? Any advice or recommendations would be greatly appreciated.

Thanks in advance!

2

Currently, there isn’t a SPE technology that will be able to achieve 500Mbps over 500 meters; it’s just not really physically possible with the current encoding schemes.

The closest is 100BASE-T1L but that’s not really released yet.

I haven’t seen any plans for a 1000BASE-T1L (Long range gigabit single pair ethernet) yet.

The closest thing yould could try is G.Hn, which is designed to achieve speeds up to 2.4Gbits over power lines. I’ve speed ranges of 300 meters suggested for that. However there isn’t much on the market, generally G.Hn isn’t used a whole lot in industrial applications.

To be honest, to achieve that kind of data rate at that kind of range, you need to be using fiber. Ultimately you’re hitting up against the physical restrictions of electrical signalling over copper. On fiber, you don’t have the same kind of distance restrictions.

For example, you could use an 1000BASE-LX SFP module with multi-mode fiber, which would give you 1Gbps up to 550 meters.

Of course, using fiber is a bit more expensive, and you need a way to integrate that fiber into your copper wired network using some kind of optical to electrical SFP converter. You could use our GigaBlox SFP for that, or there are fiber to electrical converters available online.

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3

Thank you @josh-elijah for such a detail answer.
i’m curious to know what is the maximum speed we can achieve on twisted pair cable and on how much maximum length? and what is the max speed which we can achieve on a 300m , 400m and 500m length using Botblox modules available.

4

How long is a piece of string :wink:

It heavily depends on the type of cable you’re using and the communication protocol you’re using.

Let’s assume you’re using 28AWG UL1061, twisted pair, unshielded cable (like the kind you’ll find in CAT5e).

Using 1000BASE-T1 (What SPEBlox uses) you’ll get around 22 meters maximum at 1Gbps. It doesn’t scale downwards with distance though. In other words, you won’t get 100Mbps at, say 100 meters, you’ll simply get no link. As you approach the 22 meters, you’ll start dropping packets, and then as you increase cable length, it will drop to zero). This is all to say, 1000BASE-T1 runs at 1Gbps only.

Using 10BASE-T1L (what SPEBlox Long uses), you’ll get 10Mbps up to 1000 meters. Same kind of thing, as you approach the distance limit, you’ll start dropping packets, and then as you increase further, the link will drop.

This is a bit different to other technologies like G.hn and homeplug (called powerline technologies). Those technologies do tend to scale data rate down as you increase distance (rather than dropping out completely like Single Pair Ethernet).

BlueRobotics sell a module that can achieve 80Mbps up to 300 meters, but mileage varies based on the cable you use. This is typical of a powerline device.

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