Wednesday, February 9, 2011

Packet Radio: App For The Apocalypse

In "Apps for the Appocalypse" (sic), Bre Pettis says this:

"Local wifi IRC: I want an app that creates a localized IRC channel that anyone within wifi range can join. The idea here is that wifi can't be jammed locally, so it would be nice to set up a localized network to chat with your neighbors without leaving the house. Bonus points if it can act as a node. This may already be possible, but it's definitely not easy. I'd like to just open my phone, turn on wifi, run the app and see IRC chat rooms within wifi range of my device. Bonus points for being able to make the nodes into a network. Extra bonus points for sending a message chained via wifi devices across a continent."

That sounds a lot like packet radio, to me. I'm not the only one who thinks so, either: in "Get Internet Access When Your Government Shuts It Down," Patrick Miller and David Daw have this to say:
"Given enough time and preparation, your ham radio networks could even be adapted into your own ad-hoc network using Packet Radio, a radio communications protocol that you can use to create simple long-distance wireless networks to transfer text and other messages between computers. Packet Radio is rather slow and not particularly popular (don't try to stream any videos with this, now), but it's exactly the kind of networking device that would fly under the radar."

It actually takes very little time, and doesn't require any pre-existing networks. A packet modem connected via three wires to any radio transceiver instantly becomes a stand-alone BBS, and is capable of connecting with any other such BBS it hears on the frequency, thus becoming the start of a network. It's not limited to ham radio, either; any radio transceiver will work. Its use on CB and FRS is not currently legal in the US, but I have heard of people doing it regardless. In a societal breakdown, such statutes would be irrelevant anyway.

Back in the early to mid '90s, I progressed from dial-up BBSes to packet radio on the 2 Meter ham radio band. What drew me to packet radio was that it worked from anywhere and was completely libertarian in nature. That is, it didn't rely on any paid or public-served networks, such as the utility grid or telephone lines. I don't have anything against the telephone lines, but they can be cut and at any rate must be paid for. Besides, I have spent large portions of my life without access to a landline. Right now, for instance.

Packet radio doesn't even require a computer. A packet TNC (terminal node controller) is a smart modem, with a built-in processor, memory and firmware. All you need is a two-way audio and keyline connection to a radio; and a terminal of some sort when you wish to log on. That terminal can be any old computer or even a dumb terminal. I used dumb terminals that I got for free, and also TRS-80 aka Trash-80 Radio Shack computers that I also got for free. I picked up a half dozen of the latter from the side of the road where they were being thrown away. They had one major advantage over the terminals: they allowed me to store emails and text files after I downloaded and read them. I even had a portable packet system consisting of a TNC, 2 Meter HT (walkie-talkie) and an HP100LX (later upgraded to an HP200LX) palmtop computer. Because 2 Meter networks are accessible just about everywhere in North America (much more so than cellphone networks), I could log on and send and receive email even while backpacking.

So how does packet radio work, from a practical standpoint? Pretty much the same way a dial-up BBS works, except via the airwaves instead of phone lines. But there's more, too. Every TNC has the ability to digipeat, or act as an automated relay for any signal it hears. That is a function that the city dweller might not enable, because it would really offer no advantages in an area containing many stations; but those in outlying areas would enable, to act as a relay for a station that is out of range of the BBS. And because every TNC also has the inherent ability to function as a BBS, there doesn't even have to be a central BBS in a given area. Of course, in a highly populated area, at least one operator elects to set up a dedicated BBS; but in a sparsely populated area, each station can be a mini-BBS.
The linking technology goes beyond digipeating, too. Most TNCs have the built-in capacity to become a node (similar to the nodes found on Fidonet), thereby automatically making every station it hears part of a transparent, user-friendly network.

Packet is not a replacement for the modern Internet. The basic plug-and-play TNC that is suitable for use with a VHF FM transceiver operates at a transfer speed of 1200 baud. Higher speeds are possible, but are more technically involved and require more radio spectrum, which limits use to microwave frequencies. For that stuff you can still set up a network of wireless routers, but a wireless router will not cover a 3000 square mile area with a simple station. VHF packet will. At 1200 baud, it is pretty much text files only.
In fact, the average person already uses packet radio. It is called SMS. That's right; the text messaging system in your cellphone. The cellphone has a built-in TNC, and it stores messages for you to view later, if necessary. But it has three disadvantages: it relies on a commercial network that may be overloaded or shut down; it is a paid service; and there is no BBS. Packet radio uses exactly the same technology, but without a central network that all messages must be routed through, without the paid access, and with the addition of BBSes. In short, it gives you the technology of text messaging, email and an online bulletin board, but without the middleman.

Packet TNCs have another aspect too, for those who are concerned about an SHTF event: security. Think about SHTF fiction like "I Am Legend" or AMC's recent show "The Walking Dead". One thing the survivors did was to get on the radio on some kind of set schedule, and try to make contact with other survivors. This has a few problems. First, there is the problem of range. It is not like in "The Walking Dead" where somebody whispers into a walkie-talkie from wherever they happen to be, and at whatever time they feel like it, and someone out there will hear them. It just doesn't work that way. Those walkie-talkies work now only because there is a central repeater with a high tower, that hears the weak signal from the walkie-talkie and retransmits it. Without that repeater, the range of that police radio depicted in "The Walking Dead" wouldn't be much over a mile or two, unless you can get to the top of a ridge or tall building. And therein lies the second problem. If I were a bad guy trying to find the protagonist of such a story, I would look around for the best place to transmit from, then I would just hide and wait for the guy to return. That doesn't even require triangulation. A better option for the survivor would be to program a TNC to transmit a short beacon every hour, both as a packet text and a short Morse code message for those who may not be equipped with packet radio. Then connect the TNC to a radio, which can be a simple single-channel, crystal controlled radio. Place this, along with a battery pack, in an ammo can with an antenna mounted to it. Then place the ammo can atop a building, or in a tree on a hilltop. Maybe add a solar panel to keep it charged. Now all you have to do is log on remotely with a portable packet station. You could do this from 50 miles away, by pointing a directional antenna at the hill or building. The Morse code signal could direct listeners without packet capability to transmit from the vicinity of the digipeater at a certain time each day, and you could use the same directional antenna to listen for them.  

A complete packet networking station

Even if you are not a ham, if you include a CB, MURS, GMRS or even FRS radio transceiver in your preparations (and you should), you might want to consider adding a TNC and perhaps a book about packet networking. That way if the Internet gets shut off, tightly controlled, or fails due to power grid problems, you still have the ability to network via computer. Even if the power grid failed, a deep-cycle battery and a single solar panel would keep a system like this on the air indefinitely.
For more information, check out Kantronics. They made the TNC shown in the photo, and packet radio is their specialty.
If you want an even simpler setup, Alinco makes a radio with a built-in TNC.

5 comments:

T.B.S. said...

I'll have to check into HAM now. I had no idea the technology for such sustainable networks was so readily available.

Nan said...

Interesting article. IMHO, it would be difficult in the US to pull off a shut-down like the Egyptian government did, or to control internet traffic as thoroughly as in China because our "network" is actually multiple networks with fewer choke points. It's much, much easier to simply control the information most people see and/or read. Just keep the sheeple entertained with celebrity gossip -- Charlie Sheen's latest escapades -- and 90% of the populace will ignore everything else.

Nathan said...

What software do you have on the HP200 and how do you connect it to the KPC-3??

Tracy said...

I just use the factory OS that is in the firmware. It includes a terminal emulation that is simple to configure to the TNC. I bought a serial cable that fits the HP200LX and interfaces to the RS232 port on the back of the TNC. It is no big deal; the HP200LX uses the same line levels and connections as any other serial port.

somchy said...

I used to use packet radio years ago. With the right radio, high frequency, you can send and receive messages from around the world.

The store and forwarding aspect of this system is amazing.