Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Ask HN: What's with the DIY state of the art long-range Wi-Fi?

news.ycombinator.com

Post reply on HN
Print view View original

61–67 of 67 posts

Re: Ask HN: What's with the DIY state of the art long-range Wi-Fi?

#61

Post by mikewarot »

If you want to take some of the mystery and "black magic" out of RF, I'd recommend spending time with a few things.

A NanoVNA - (less than $200 on Amazon/Ebay) This little tool will help you understand how transmission lines work, along with antennas, matching, etc. You can use them to test antenna matching, and gain, etc. If you want to roll your own high-gain antennas, etc.. this is an amazing piece of kit to have at a low price.

Not as directly applicable, but effectively free. GNU Radio -- This will give you a feel for signal processing, and how RF stuff works internally... it works with audio I/O so you can experiment for effectively $0. If you get to the point where you understand I/Q signals and "negative" frequencies, a lot of things become clearer.

Re: Ask HN: What's with the DIY state of the art long-range Wi-Fi?

#62

Post by tlavoie »

MayeulC wrote: post #48
hoppla wrote: post #22

Earlier quoted context omitted.

A curiousity about Ubiquiti firmware. It seems like the AP firmware is based on openwrt

And IIRC a lot can be flashed with openwrt too!

Oh, that would be handy. I have a couple, and they work just fine as regular APs. However, the odd time I do need to make changes, it's going through the whole bloated UI and management app (with MongoDB etc. installed). Really, I'd be quite happy to just run independent OpenWRT on them, since I don't need to integrate with larger infrastructure.

Re: Ask HN: What's with the DIY state of the art long-range Wi-Fi?

#63

Post by courgette »

efxhoy wrote: post #45

I did long range (50km) radio links in the Swedish army 10 years ago. If you want to have the best possible impact I suggest you work with existing telecom companies and ISPs. They have the knowledge and the resources. Nothing you can hack together is going to beat commercial radio links mounted in actual towers and regular phone transmitters.

OP, this person mentioning towers is saying something really important here. Those structure are not here without reasons.

It works, so, so much better with actual towers.

Re: Ask HN: What's with the DIY state of the art long-range Wi-Fi?

#64

Post by grepfru_it »

asdfkjhasdfhuh wrote: post #60
MayeulC wrote: post #48

Earlier quoted context omitted.

And IIRC a lot can be flashed with openwrt too!

their NICs will not work with regular kernel drivers. you will lose the only edge their hardware have which is dealing with a stupid large number of clients. everything else (speed, uptime, ram/cpu power, beanforming magic, etc) you are better off with linksys devices when using open source drivers.

>speed, uptime, ram/cpu power, beanforming magic

I literally have none of these problems and I run ubiquiti everywhere

Re: Ask HN: What's with the DIY state of the art long-range Wi-Fi?

#65

Post by asdfkjhasdfhuh »

grepfru_it wrote: post #64
asdfkjhasdfhuh wrote: post #60

Earlier quoted context omitted.

their NICs will not work with regular kernel drivers. you will lose the only edge their hardware have which is dealing with a stupid large number of clients. everything else (speed, uptime, ram/cpu power, beanforming magic, etc) you are better off with linksys devices when using open source drivers.

>speed, uptime, ram/cpu power, beanforming magic I literally have none of these problems and I run ubiquiti everywhere

I also have a small compact car and it is fine for me to drive it every day to work, market, etc. Doesn't mean an expensive sports car is not much, much faster.

The irony is that here the compact car is more expensive :D maybe the correct analogy is a minivan, since it can hold more clients. but still, more expensive than the TP-Link sports car.

Re: Ask HN: What's with the DIY state of the art long-range Wi-Fi?

#66

Post by namibj »

mNovak wrote: post #41
jacquesm wrote: post #12

Earlier quoted context omitted.

Seconded, Freifunk is easy to use and pretty resilient, there is also a pretty large community of people with knowledge about it and the hardware requirements are as low as they will go. Beware of some of the possible downsides: the default is for Freifunk nodes to be placed on a map and I'm not sure if this is a requirement or not but it might provide easy targeting information for the Russians. This will have to be…

I'm not very familiar with Freifunk, but if it interfaces like a normal WLAN to the user, then simply not advertising SSID and a basic password will go pretty far. This is obviously not secure against any sort of special operative, but eliminates it as a very easy convenient tool for e.g. a mobik with a cell phone, if this finds its way anywhere near a frontline. An upside of highly directive, P2P links is that they…

While not sure if it will help/matter for the OP, I'd like to confirm the idea/thought of using (ground-plane-having-for-back-lobe-suppressing) axial-firing helix antennas, in pairs, to do circular polarization MIMO on the point-to-point long-distance links. So one clockwise and one counter-clockwise helix, connected to the two antenna ports on a cheap 2.4 GHz router.

Gain seems to max out around 15 dBd, in that case, for a 90cm long antenna of ~5cm diameter. The beauty of circular polarization there is the independence of mounting angles/matching rotations, but I guess a small forest of H/V dual-polarization Yagi's (or, for routers with 3X3 MIMO, 3 equally-spaced polarization directions, assuming that works without breaking the workings of the Yagi) might be easier due to the potential for a solid metal center pillar to hold the elements.

A forest instead of a lone Yagi would be to increase gain more efficiently than by merely elongating a single Yagi, as the latter would quickly cause mechanical issues in wind.

I'm imagining access to an improvised spot welder to attach lengths of copper wire to a steel support pillar, then finished with some paint as an anti-corrosion coating. Or some more low-tech attachment process, like a styrofoam pillar with the wires pierced through in the right spots, mounted either indoors or in a drain pipe or such for weather protection.

Can you confirm that these approaches are appropriate for the situation/call some out that are not appropriate?

Re: Ask HN: What's with the DIY state of the art long-range Wi-Fi?

#67

Post by Technetium »

sandreas wrote: post #56

Here are some things I collected: 1.) Raspberry PI Zero antenna mod: https://www.youtube.com/watch?v=IZqaKZLIqFg 2.) Cheap DIY Antennas: https://www.youtube.com/watch?v=TPt-sw3kvw0 Be sure to check out this guys whole youtube channel (@andrewmcneil), he is awesome and its about DIY antennas (from cheap to expensive with real in depth tests) 3.) There also is a ready to use but expensive product from Ubiquity called "…

For more info on Ubiquity products, I'd recommend Lawrence Systems: https://www.youtube.com/user/TheTecknowledge
Post reply on HN