(This was originally published on N8GNJ.org, and copied here; SuperPacket is now my "big picture of Amateur Radio" blog for articles like this - see About SuperPacket.)
Amateur Radio Emergency Digital Network (AREDN) is a firmware image for selected Wi-Fi access points and Wireless Internet Service Provider (WISP) units. AREDN's firmware adds various services such as Domain Name Service (DNS) and Dynamic Configuration Host Protocol (DHCP) and most notably, hands-off mesh networking (sometimes called peer to peer networking). As part of the AREDN firmware, it enables the Wi-Fi radio to use a portion of the 2.4 GHz band that is only legal for use by (licensed) Amateur Radio operators. You don't have to be an Amateur Radio operator to use the firmware, but you do have to be an Amateur Radio operator to make use of the additional channels.
AREDN is useful enough that I think every ham that has a Go Kit with a computer, should have a few AREDN nodes in their go kit. My rationale for making that statement is one of the issues that Amateur Radio operators have in responding to emergencies with their go kits (again, with a computer) is that there is no good, and certainly no easy way to have their computer communicate with other Amateur Radio operators. I've observed many, many times when computer-to-computer communication devolves to putting a file on a USB memory device that's then "sneakerneted" to another computer. AREDN units are a fix for that. AREDN is mostly "plug and play" to use, but some preparation is required.
The easiest way to understand and experiment with the potential of AREDN is the GL-iNet GL-AR150 shown above. It's around $25 on Amazon - buy two for your experimentation. The model in the photos above has an internal antenna. The GL-iNet GL-AR150-ext features an external antenna port and a small antenna. The big brother of the GL-150 is the GL-750, which is a bit more expensive, but has the benefit of a 5 Ghz radio in addition to the 2.4 GHz radio.
The best way, I think, to think of AREDN nodes for this use case is that they're the rough equivalent of an Ethernet switch and Ethernet cables connecting multiple computers together to share resources, such as a local web server, file sharing, or any other service we take for granted via the Internet - as long as it can be hosted locally. Think email via POP/SMTP, but not Gmail.
After it's flashed with the AREDN firmware, there is some minimal configuration required, including entering your callsign and setting up a password. I recommend installing the tunnel software (allows you to create a Virtual Private Network - VPN to other AREDN nodes via an Internet connection). The tunnel software doesn't take up much room and it's much, much easier to do it when you have a good Internet connection rather than adding it later on a marginal or no Internet connection. Unlike the initial firmware installation, the tunnel software must be done "live" - you can't download it for later installation.
(Apologies that I'm describing all of this with words rather than photos - a future version of this will include photos.)
Then it's as simple as providing the AR150 power via USB (it doesn't need much - a computer's USB port is adequate) and plug the AR150's LAN Ethernet port into the computer's Ethernet port. Assuming you select the default radio settings, any other AREDN node within range (with the same radio settings) will automatically connect into a mesh network.
The real power of AREDN is the services beyond the AREDN nodes. In my example above of multiple Amateur Radio operators in a shelter, one computer can be configured as a web server, advertise that server on that particular AREDN node, and then anyone else in the AREDN mesh can click on that advertised service and see the web page.
The use case I'm describing here hasn't been discussed much (that I've seen).
I have a mild criticism of AREDN that they posit its role as outdoor infrastructure, and in my opinion, that's somewhat impractical. 2.4 GHz is hard enough to make work, even with the "quiet" portion of spectrum that AREDN is using. The better model for Amateur Radio high-speed microwave infrastructure, in my opinion, is HamWAN. Alternatively to HamWAN's way of doing things, you can buy off-the-shelf Wireless Internet Service Provider (WISP) equipment designed for this purpose (thus, it's expensive). Vendors of WISP equipment include Cambium Networks, Ubiquiti Networks, and MikroTik. While this is equipment intended for WISPs, because it uses license-exempt spectrum (generally 5 GHz), it can be purchased and used by anyone. One good vendor of such equipment is Streakwave Wireless. It's a bit of work to get them to work with an individual, but they're willing to do so.
I'm now able to access two AREDN Virtual Private Network tunnels, one for my fellow Amateur Radio operators in Whatcom County, and another for my buddies in the Seattle area. One issue to be careful about is routing loops so I'm careful to keep the two networks segmented for now, as I want to experiment on both of them. I have two sets of AREDN nodes in my shop, and they don't interoperate with each other because of of unique radio configurations for each group.
My friend Bill Vodall W7NWP made a good set of notes on configuring the AR150s.
Next steps in experimenting with AREDN:
- Configure a Raspberry Pi as a web server and advertise that service via AREDN
- Configure my new TP-Link 2.4 GHz radio to try to connect with the nearby AREDN node,
- Learn more about advertising services, such as VOIP, email, etc. via AREDN
- Order more AR150s, get them configured into a Go Box configuration with their own battery packs, weatherproof boxes, and better antennas for better range.
Update 2 - 2021-02-23 - Displaying a web page on an AREDN Node, from the AREDN node
The one thing I wished was possible on the AREDN nodes was to display some custom text like a small web page. It would be ideal if this was automated, like a checkbox to display custom text. When I plainted this desire to my long-suffering techie buddy Bill Vodall W7NWP, he was completely puzzled - "Steve... it has a web server already running. You're looking at the status page in a web browser, aren't you?". That was my D'oh moment. So then Bill and I went on an hours-long quest to figure out how to access it. Turns out you can ssh and scp into your AREDN node - IF you know what you're doing.
Part 1 - Make a simple web page
You can't effectively make changes to a file from / on the AREDN node. Well, technically, you can, but you the only editor available on an AREDN node is the vi(le) editor. Life's too short.
So, compose a web page that you want to be resident on your AREDN node on your "big" computer. It needs to be "something".html. Keep it simple. Compose in an HTML editor or a text editor, and keep it to text only (no images). Save it as a simple text file. If you're rusty on your HTML, as I was, here's an HTML intro.
Save it as n8gnj-test1.html (whatever name makes sense to you). Make sure you can find this file when you're in the command line using SSH.
Be sure to view your file in a web browser:
http:///path/filename
Part 2 - SSH
ssh -p 2222 root@n8gnj-1
ssh is Secure SHell. -p specifies the port which on an AREDN node is 2222 for ssh and scp. root is the username on the AREDN node, and n8gnj-1 is the system name (technically, it's N8GNJ-1 but the system doesn't seem to mind, and it's easier not to shift to all caps.
Also, the system doesn't seem to care about using n8gnj-1 vs using n8gnj-1.local.mesh, so I used the former.
and you're prompted for the node's password, and you're in!
But that was only part of the battle, but at least I could look at the file system from the inside.
Part 2 - SCP
The beauty of UNIX / Linux is that the tools like SCP have been honed over decades. They work... you just have to know how to use them. The available documentation, especially on a system, like man scp are terse at best. So it took Bill and I hours to get this right. Well, to be fair to Bill, it took him tens of minutes to get it right (based on my feedback) and it took me hours of fiddling around.
scp -P 2222 n8gnj-test1.html root@n8gnj-1:/www/n8gnj-test1.html
scp is Secure CoPy. -P (note that for scp, it must be an uppercase P) specifies the port which on an AREDN node is 2222 for ssh and scp. root is the username on the AREDN node, and n8gnj-1 is the host name.
n8gnj-test1 is the file that I created on the "big" computer.
The fiddly bit was the :/www/n8gnj-test1.html. :/www/ specifies that the scp command copies the n8gnj-test1.html file into the /www directory of the AREDN node. (You have to know a valid directory in advance of this command, thus it's useful to know how to use ssh). something2.html is the name of that file when it's copied onto the AREDN node (in the /www directory).
and you're prompted for the node's password, and if everything is correct, scp terminates. Then go back to ssh, and look at the /www directory, and there should be a something2.html file there.
At this point, you've moved a file into the file system of the AREDN node. Then, you get to get to do configuration magic to display it from the main AREDN node status page.
Part 3 - Configuration of a link to display
(Apologies that this next part is terse - I want to capture it before I forget these fiddly bits.)
Go to Setup, Advertise a Service.
- Name Box: (what name you want to appear under the Services column next to your node in the Mesh Status page) I put N8GNJ Simple Web.
- Click the Link checkbox (it will appear as a clickable link)
- First box - HTTP (pulldown, I think)
- Second Box - select your node from the pulldown. In my case it's N8GNJ-1.
- Third box (after the :) 80 (port number, apparently; Port 80 is universal for HTTP).
- Fourth box is the name of the file in /www. In my case it's n8gnj-test1.html. (Apparently the /www is prepended and no need to have it in the string - just the filename.)
- Click the Add button. It'll take a few seconds for it to update.
- Click the Save Changes button (above). It'll take a few seconds to save this new configuration.
Normally, this capability is used to advertise a service on another system; there are dozens of examples. Mine was going to be a web server running on a Raspberry Pi, but what I wanted to display is pretty simple, and it seemed like this should be possible, but there were only the vaguest of hints that this was possible, and how to actually do it, on the AREDN pages and forums.
Part 4 - Display the Web page
Now, in the mesh status page, next to my node N8GNJ-1, there is an advertised service - N8GNJ Simple Web that is clickable. When clicked, it displays the very simple HTML text that I put in there. What's really unique about this is that it's a web page that's stored on the AREDN node, and it's being served by the AREDN node.
Thanks again Bill!
Update 1 - 2021-02-22 - AR-750 can offer Wi-Fi on 5 GHz in addition to AREDN on 2.4 GHz
In a running conversation I'm having with another Amateur Radio operator, it occurred to me that the GL-iNet GL-AR750 has a unique capability vs other ARDEN nodes because it has a 2.4 GHz radio and a 5 GHz radio. When you flash an AR750 to AREDN firmware, the 2.4 GHz radio is reprogrammed into AREDN's configuration for meshing with other AREDN nodes. But the 5 GHz radio isn't reprogrammed - it remains compatible with Wi-Fi. That capability enables this (theoretical) scenario:
- The big one happens - earthquake, power failure, ice storm, etc. Cellular service is out. This isn't THAT theoretical; I was without cell service for a week in Woodinville WA in the aftermath of a severe winter storm that toppled MANY trees onto the power lines. Power was out for that week, and the small cell sites that service most of Woodinville didn't have standby generators, only batteries, and those were depleted after 12 hours or so.
- People need to communicate their status - email is the most practical.
- A "package" of an AREDN AR-750 with a high capacity battery pack, is put into a tree or other high, central point.
- The AR-750's 2.4 GHz radio meshes with others.
- The AR-750's 5 GHz radio is avilable for access by "civilians". (Yes, this is legal because a ham is in charge of the network - a "control operator".)
- Civilians are able to use their phones to connect to the 5 GHz Wi-Fi Access Point on the AR-750.
- Civilians then open the web browser on their phones and are greeted with a "splash page". That capability requires some development.
- Civilian fills out a form on the web page and then that's upload to a control operator on a laptop somewhere in the mesh.
- Civilian gates out the email into the Winlink system and Winlink handles delivery of the email.
Blast from the Past - Linux Routers and Amateur Radio Spread Spectrum
In doing some research for another article here on SuperPacket, I ran across a prescient statement I made to Linux Gazette (later, Linux Journal?) that routers and gateways used in Amateur radio would be based on Linux. My statement must have made an impression because Linux Gazette posted it on their website.
Subject: TAPR SS Position Statement
Date: Thu, 26 Sep 1996 12:18:44 -0700 (PDT)
From: Steve Stroh
To: Phil Hughes WB6SWR
I suspect that the "Intranet" described below will be built on Linux-based IP routers, possibly a simple implementation that can be booted from floppy or Flash Card.
It's going to be very, very interesting.
Steve N8GNJ, <old email address redacted>
Amateur Radio TCP/IP <old email address redacted>
| Amateur Spread Spectrum is the wave of the present!
...
Fast forward sixteen years... When the Raspberry Pi computers came along in 2012, I knew that they were going to be very popular in Amateur Radio. Finally we had a powerful (enough) inexpensive embeddable computer that ran a powerful operating system that could be "headless" and scriptable and stable. Before then we had embeddable computers that were expensive, Linux was fussy and non-standard on embedded devices, and most Amateur Radio software was running on Windows.
Below is the meat of that email to Linux Gazette.
...
TAPR's Statement on Spread Spectrum Technology Development
http://www.tapr.org/
TAPR was founded in 1982 as a membership supported non-profit amateur radio research and development organization with specific interests in the areas of packet and digital communications. In the tradition of TAPR, the Board of Directors at their Fall 1995 meeting voted that the organization would begin to actively pursue the research and development of amateur radio spread spectrum digital communications. At the Spring 1996 board of directors meeting, the following statement of purpose was passed:
"TAPR believes that the technical facts support our conviction that conventional and spread spectrum systems can coexist without detriment to conventional systems on all frequencies from MF to EHF. To this end, TAPR will begin to research spread spectrum systems that will develop technology for future deployment."
As stated above, the TAPR board feels strongly about TAPR's focus on spread spectrum technology and especially how it relates to the potential coexistence on frequencies that will have increased number of users occupying them. The amateur radio bands, like other spectrum will become more heavily utilized in the future. It is in the interest of amateur radio to develop systems that are interference-resistant while not interfering with other primary or secondary users on those frequencies.
TAPR understands the concerns many have with the new technology, and believes that efforts in both education and research is necessary in order to allay the fears about interference and to demonstrate the benefits of the technology.
TAPR believes that todays' communications technology is moving toward all digital transmitters and receivers. These advances in technology, combined with the swift evolution of cell based transmission and switching protocols, are opening up a new set of possibilities for unique new services utilizing intelligent networks. These will contain smart transmitters, receivers, and switches. Today's Internet is perhaps the best example of a self-regulating structure that embodies these new technological approaches to communications in the networking domain. However, to date, many of these innovations have not moved into the wireless networking arena. TAPR will work on moving these innovations into the amateur radio community.
TAPR feels that the VHF/UHF/SHF radio networks of the future will involve a mixture of links and switches of different ownership, which terminate at the end-user via relatively short-distance links. What will then be required is a built-in, distributed, self-governing set of protocols to cause the network's behavior to make more efficient use of a limited, common shared resource, the radio spectrum. Creating such a self-regulating structure for the optimal sharing of spectrum will require much effort.
One of the major problems which stands in the way of these new approaches today is the current FCC regulatory environment and the manner in which spectrum is managed and allocated under its rules.
Historically, the current regulatory approach to radio has been based upon the technology that was in use at the time that the Communications Act of 1934 was framed, basically what we would call today, 'dumb' transmitters speaking to 'dumb' receivers. The technology of that time required reserved bandwidths to be set aside for each licensed service so that spectrum would be available when needed. Given this regulatory approach, many new applications cannot be accommodated since there is no available unallocated spectrum to 'park' new services. However, given the new set of tools available to the entrepreneur with the advent of digital technology, what once were 'dumb' transmitters and receivers can now be smart devices which are capable of exercising greater judgment in the effective use and sharing of spectrum. The more flexible the tools that we incorporate in these devices, the greater the number of uses that can be accommodated in a fixed, shared spectrum.
Therefore, TAPR will focus its spread spectrum effort in the following areas:
TAPR will work to promote rules and technologies to make the most efficient use of the spectrum through power control, forward error correction, and other means to minimize interference among spread spectrum users and existing communications systems.
TAPR will work on issues and efforts with other national organizations to change the regulatory environment and rules in order to promote the experimentation, development, and later deployment of spread spectrum technology.
TAPR will work to develop information on the topic to help educate members and the amateur community as a whole about spread spectrum technology, and to disseminate this information via printed publications, the World Wide Web, presentations at conferences and meetings, and other means.
TAPR will work to foster experimentation, development, and design of spread spectrum systems, and to facilitate the exchange of information between the researchers and other interested parties.
TAPR will work to develop a national intra-network to foster the deployment of future high-speed spread spectrum systems into regional and local communities, including the development of suitable protocols and guidelines for deployment of these systems.
TAPR will work with commercial companies who manufacture spread spectrum devices which operate in spectrum shared by the amateur radio service (ARS), in order to make them more aware of the nature of ARS operations on those bands with the goal to work towards the deployment of devices which will minimize interference between all spectrum sharing partners.
TAPR will work with commercial companies who manufacture spread spectrum devices in order to identify equipments that can be either used or modified for use for Part 97 operation.
Adopted by the TAPR Board on September 20th, 1996 at Seatac, Washington Board Meeting.
Spread Spectrum Statement Committee:
Greg Jones, WD5IVD
Dewayne Hendricks, WA8DZP
Barry McLarnon, VE3JF
Steve Bible, N7HPR
...
TAPR joined an existing Special Temporary Authority (STA) investigation to operate Spread Spectrum in Amateur Radio spectrum. If memory serves there was a second STA established solely by TAPR. Both STAs concluded with a report to the FCC that Spread Spectrum operations were usable in Amateur Radio spectrum. Years later, the FCC finally made some rule changes regarding Spread Spectrum in Amateur Radio spectrum. The FCC's new rules were overly cautious regarding Spread Spectrum operations by Amateur Radio operators with onerous restrictions on power levels that the American Radio Relay League insisted on to protect legacy modes. In 2021 Spread Spectrum operation in Amateur Radio is "common", but only in the bands that Amateur Radio shares with / adjacent to Part 15.247 devices, namely in the 902-928 MHz, 2.4 GHz, and 5 GHz bands.
I participated in one or both of the STAs. In my report to the FCC, I concluded that Frequency Hopping Spread Spectrum (FHSS), even at high power levels, was completely compatible with Amateur Radio operations in Amateur Radio VHF and UHF bands, due to the minimal "dwell time" on any one portion of an Amateur Radio band. In 2021... due to the very minimal use of repeaters for voice communications, my conviction of the usability of FHSS in Amateur Radio is even stronger.
Amateur Radio dreamed bigger back then. I hope that with some new capabilities, Amateur Radio can dream big again.
Thanks for reading!
Steve Stroh N8GNJ
Bellingham, Washington, USA
2021-05-07
Posted by Steve Stroh on May 07, 2021 at 11:26 AM in Amateur Radio Future, AREDN, General Commentary, Microwave, Regulatory | Permalink