Running Ethernet over existing coaxial cable
til.simonwillison.net
til.simonwillison.net
If some conductors aren't connected, have bad connections, or the order of wires is wrong, then many gigabit ports will negotiate to 100 Mbps, which only requires four working wires out of the eight.
A cable tester from Micro Center (if you're lucky enough to have one close enough to visit) is $7.99, plus a 9 volt battery (which, funnily, is about half the price of the cable tester). Amazon has the same testers for around $10.
MoCA is great, particularly if you're using cable boxes that require Internet over MoCA and you want to replace the NAT router your ISP provides, but it's a bit silly to use MoCA when you have wires that probably just need to be re-terminated or terminated properly.
I'd much prefer a consistent <1ms latency 10 Mbit connection than 10ish ms gigabit with 100ms spikes when next door boils their kettle, etc.
Most home users aren't going to really notice or care about a 6-7ms latency for even network file protocols. They're probably using Wi-Fi anyway.
My MoCA devices don't use crazy amounts of electricity either.
It could also depend on where you are. In the US, homes often have quite good coax wiring. That might not be the case in many parts of the world.
> I'd much prefer a consistent <1ms latency 10 Mbit connection than 10ish ms gigabit with 100ms spikes when next door boils their kettle, etc.
Honestly, this just feels like FUD. You've made up a scenario with latency numbers that are wrong claiming with zero support or evidence that a neighbor boiling their kettle will make a connection bad. It sounds like you briefly looked at MoCA, never tried it, but formed a very strong opinion about it based on basically nothing.
3.5 ms is between 5x - 53x worse than what you'd see out of gigabit ethernet, depending on the quality of the equipment, but even at the low end this is absolutely something noticeable in any application heavy on round-trips (such as those mentioned). Nothing breaks my focus more quickly than an unpredictably slow or janky UI, it is far from a made up scenario, just open an explorer window pointing at an SMB share with a few hundred JPEGs with uncached thumbnails and you've already hit it. I'd much prefer consistency of a slower network than usability that evaporates at random, else what is the point of preferring a wired network over wireless in the first place?
FWIW, listing a directory or opening a single file over SMB is at least 4 round-trips, that's 14 ms burned on lag just for a single thumbnail, in the best case, and it only multiplies from there.
5e will handle gigabit, and I've seen 5 work for short runs too.
5 has the same bandwidth as 5e but allows more crosstalk. And gigabit is intended to work on cat5. If gigabit is not working on cat5 cables <50m, I put my money on there being something wrong with the hardware/install in that house.
I have 10g-base-t running reliably on cat5e as well. (30ish meters)
In summary, general tradespeople don't know how to install Ethernet.
Despite claims to the contrary, gigabit will work over cat 5 (just not 5e!) in the majority of cases.
This house did not have cat5 installed anywhere, but it had both coax and cat3 for the old school phone lines/intercom system.
During the inspection I removed some wall plates and noted that there indeed appeared to be properly installed conduit in every box I spot-checked. Inspectors noted the same.
After I moved in and got all the supplies ordered and staged to start removing coax/cat3 using them as pull strings for my expensive fancy new CAT6 wiring I found out something super fun...
The builder had decided to cheat the code inspectors by installing every single box with only about a foot of conduit attached to the boxes. After that they simply stapled the wiring to the studs every so often making pulling cable with them impossible. At least it appears they did indeed use conduit for the AC power.
Not entirely related to your point, but it's something that still makes my blood pressure increase a tick even remembering it enough to describe here.
What went from a weekend of pulling new cable with conveniently placed pull strings turned in to a month's-long ordeal of running new cat6 through the house and then another couple weeks of drywall repair for all the holes needed to do so.
Did you have any recourse against the builder? Maybe through your homeowner's insurance?
i guess catX and coax are low voltage and covered by nec
Some places have not broadly adopted the NEC at all. For instance: In Ohio, NEC adoption is handled at a more-local level, and many places simply have never handled that at all.
My point is that things like the National Electrical Code simply aren't "national" at all. Regardless of how it is named, it is a privately-published rulebook that jurisdictions can elect to use, but are in no way required to use.
What is it that you are hoping to add to this conversation?
I'm not going to review the other 49 points that your map may presume to present, for it does not refute anything about my initial claim at all even as-presented: Instead, it shows that the National Electrical Code is, in fact, not national.
There's an alternative called G.hn over Coaxial, that runs at 100-200Mhz which seems to fair much better on crappy coaxial, at the cost of max bandwidth (500Mbps-1000Mbps) and harder to get hardware.
The manufactures of G.hn2 Coaxial adapters seem to be stingy about selling them to individuals.
You'd want to start with as many pads as possible, so something like >80 dB of pad. Remove them one on by one until the reported signal level is in the middle of the acceptable range.
From the device perspective it won't really know the difference. You might need to disable antenna diversity as otherwise the APs might attempt to use one of the antenna ports with nothing connected to it.
Oh, I did the math on this before.
So you technically don't have much loss from the air itself, but you lose 6 decibels every time you double the distance from the antenna. So at the distances people normally use wifi, the loss from distance alone is higher for air than for coax. And that's not counting the 40+ decibels of loss you start with for adjacent devices with antennas.
Also sometimes the coax takes insane routes because the installer couldn't be bothered to run it the shortest distance.
It isn't hard to find a scenario where two APs with dipoles technically have less loss than a run of coax. The advantage the coax has is noise floor, which is what actually determines the bandwidth of a communications channel.
Is the impedance mismatch worse than the 40 decibels of loss you get just by having antennas? Shouldn't it be pretty small? And you can correct for it, can't you?
> The old stuff put in homes is abysmally bad for cable TV at 700 or so MHz. So at triple the frequency it is really bad.
What kind of cabling should I assume? RG-59 loses about half a decibel per meter at 2.4GHz. So if someone is 30 meters away, but it's 60 meters via coax, both methods should give them 30 decibels more loss than at 1 meter away. The total loss is still over twice as bad for the antenna connection. And that's with no walls.
What does a situation look like where the antenna technically has less loss?
But household TV coax in the States (RG-59, RG-6, RG-11, and friends) is 75 Ohm.
And impedance matters. How much it matters varies by application, but it can be very important. There's more going on in bit of coax than a shielded conductor[1]. (Relatedly, twisted pair cabling like Cat5e has more going on than a few pairs of wires that happen to be twisted.)
But the concept of having a pair of radios connected together with coax does, of course, work fine as long as the I's are crossed and the T's are dotted. I've set up PtP Wifi-ish wireless links on the bench with attenuators and coax jumpers instead of antennas, but I kept the characteristic impedance consistent throughout. (Many-to-many networks are also possible, with similar caveats.)
[1]: Similarities of Wave Behavior, as presented by Dr. J.N. Shive, 1959. https://www.youtube.com/watch?v=DovunOxlY1k
I can find several at Amazon (Germany). For example https://www.amazon.de/GIGA-Copper-Ethernet-Netzwerk-Koaxialk...
When I tried MOCA, disabling the upper frequencies on the devices would lead to a much stable performance, at the cost of speed. MOCA seems designed with cable networks in mind.
G.hn had no issues, and the latency is much lower than Moca (1-2ms vs 6ms).
I'd used HomePlug powerline for years in various houses/apartments. Some links would be 150Mb/s, others struggled to keep 20Mb/s, depending.
I had high hopes G.hn2 was going to be a lot better, but both Nexuslink & Comtrend 2Gb/s failed to make a significant difference for me versus the HomePlug, still usually under 40Mb/s. That house had particularly bad wiring it seems.
Dedicated coax could be way better. Interesting to hear a moca failed story! I didn't consider that as a possibility.
I'm self-limited to 1G because what supports 2.5G these days? Not my equipment.
This device picks up PoE power and ethernet at one end and delivers up to 21w at 100m to the remote end (less for longer runs). Enough to run most IP cameras. Speed is only 100Mbps (up to 300m, 10Mbps at 1000m) but that's more than enough for 4k live streaming.
It also supports transmission over twisted pair instead of coax. You can use that to pipe Ethernet and PoE over twisted pair doorbell or phone wire. Apparently a common usage is getting Ethernet onto older elevators over the legacy twisted pair emergency phone line. How much bandwidth and power you get depends on the quality and type of wire - in my experience it does a decent job adapting to conditions.
I did my research, bought moca adapters, and set everything up. As it turned out, the coax cables upstairs in the office... weren't plugged into anything.
I ended up just buying a flat ethernet cable and 3m strips. I put it all around the trim and both my wife and I are pretty short - so no one ever saw it. It went to a POE AP in the office.
I now own an old home. I was excited to see a bunch of coax outside, but alas, previous homeowners have either pulled out all the old coax or snipped it. There still are old holes everywhere from the coax - so hopefully one day I'll be able to snake an ethernet cable through and get an AP up.