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preferred protocol for 2 wire communication at speed

Hi Everyone,

 

Im interested to know what everyone's preference is for ethernet over two wire communications is and why.

With many new ways to transmit data at high speeds over two wires,  im interested to hear peoples reasons of choosing one over the other.

For instance

100 base T1 v Homeplug technology

1000 base T1 v G.hn technology

 

Currently I cannot see any negatives from using home plug or G.hn. They operate over almost any medium in noisy environments. T1 still really needs a twisted pair for best operation where as the others can use any copper cable.

 

All the best

 

Paul

 

Hi Paul,

This is a great question. I mainly have experience working with 1000Base-T1, but have spent considerable time researching G.hn.

I'll focus on G.hn vs 1000Base-T1 because, in general, the same reasoning applies for Homeplug vs 100Base-T1.

It's fair to say that both G.hn and 1000Base-T1 do compete and have significant functional crossover.

I think the main difference is that G.hn focuses on using existing wiring in a system, whereas the 1000Base-T1 focuses on specific cabling for new systems. In general this means that G.hn cannot define a a specific physical standard, and so the electronics needs to be more advanced to accomodate for a wide range of wiring types. This can be confirmed by looking at some of Maxlinear's reference designs on G.hn, you need a G.hn AFE ($6) + G.hn processor ($20) + Gigabit transceiver ($2) + all the rest. The signalling method is also more advanced, it appears to use a combination of OFDM (splitting the signal up into multiple frequencies) and QAM.

In contrast, as 1000Base-T1 specifies more of the physical layer, the electronics can be simpler and it can use a simpler modulation method (PAM-3 if I'm not mistaken). In general this translates directly into lower system cost and smaller size (though of course, if you're having to replace cabling to accomodate 1000Base-T1, then that cost saving is lost very quickly).

Another aspect is expandability. G.hn does a great job of "maxing out" existing wiring to pump down 1.7gbps. If you later wanted to increase that, you'd have a tough time as you're hitting the physical limitations of the copper. I believe 1000BASE-T1 will use the same wiring standards for 10GBASE-T1 and upwards, so expandability would not require any change to the wiring.

So in general I think we can summarise as...

G.hn: Ideal for situations that will never require more than 1-1.7gbps, that also have older legacy wiring. Also suitable for less space/cost sensitive applications.
1000Base-T1: Ideal for situations where expandability is required, and newer wiring can be defined (which still leverages the benefits of single pair). More suitable for space/cost sensitive applications.

Anyway that's my two cents on the matter, I'm not an expert in G.hn so I could be missing a few extra points here.