Amateur Radio!

JoshNH4H · 2013-11-22 10:39:46

In the USA, as well as many other countries, there are certain bands in the radio spectrum reserved for use by amateurs, which is to say people operating in nonprofessional capacities. I haven't started studying yet but I know that there are all sorts of bands, done for voice or data and I've even heard of AV signals (Think TV) being broadcast over these bands.

In the USA, the license is free and doesn't expire for ten years. The test seems pretty simple (I was about 80% of the way to passing without doing any kind of studying), so it's an easy license to get.

My question is, does anyone have any suggestions for what to do with the license, once I have it?

GW Johnson · 2013-11-22 12:39:40

I had two friends in college who were "hams" (amateur radio operators). One is long dead, the other spent his engineering career in avionics. For them ham radio was a hobby, and they enjoyed talking to other operators all over. Just fun.

There is another aspect to it that I know of. In times of disasters, often normal communications are knocked out. Some of the hams with their own power supplies can still provide the emergency communications pathway that sets up disaster relief.

Never was a ham myself. I did some CB radio long ago, but that's about all. CB was 11 m, close enough to my friend's 10 m ham rig that he and I could CB over longer ranges when he used his big 10 m antenna coupled to a CB radio.

GW

Terraformer · 2013-11-22 15:19:17

Ah, I'm more interested in packet radio. I want to set up an alternative mesh network, that can be expanded by anyone who wants to. Sort of an alternative to the internet, that's impossible to censor. Have meshes covering local areas, then another mesh layer on top of that that allows communication between those networks (the internet ). Maybe even add in some relay cubesats to take it global.

But packet radio is quite constrained, I gather. I wonder how much bandwidth would be available for such a system? Could we get data rates comparable with mid-90s internet?

It all ties into a wider plan of mine, don't worry.

JoshNH4H · 2013-11-22 16:29:13

Actually I was thinking that one thing I would want to apply it to would be to make some kind of basic data net that could be reached from Baltimore City and surrounding areas. I'd want it to have a range of about 25-30 km (My job is about 20 km from my apartment and that's as far as I travel on a regular basis). Assuming it's accessible to within 25 km of where I live, that would contain the entire area of Baltimore City (630,000 people) and much of the population of Baltimore County (about 810,000 people in the county, of which I'd bet around 650,000 live within that radius) giving a total potential reach of over a million people. Seeing as the UK is pretty densely populated, I'd expect that you would have a similar reach.

It occurs to me that 25 km may be overly ambitious given that amateur broadcasting is limited to 1500 W. I'm not really sure. Regardless, I should be able to reach most of Baltimore City.

I don't know what the process for getting an amateur broadcaster license is in the UK but perhaps we could work together on establishing similar networks in the two countries.

GW Johnson · 2013-11-22 17:36:23

Your effective range depends upon your frequency, and upon atmospherics. Sometimes 10 to 80 m FM ham radio reached several dozen miles, sometimes it would bounce intercontinental. It's inherently iffy.

AM broadcast is fairly reliable for dozens to hundreds of miles at several KW transmitted power. But it's low-quality, noisy, and subject to easy disruption.

GW

Terraformer · 2013-11-22 17:45:01

Some sort of Bulletin Board System, perhaps? Depending on data rate ability, it could go even more ambitious and let people create their own pages, accessible by anyone in the mesh. I'm trying to find out what the data rate that's achievable using freely available frequencies is. I think it's somewhere around 9.6kbit/s? We should be able to achieve 1KB/s then, between devices. Call it 200 words/second, if each word is an average of 5 characters long. Maybe 150 words/s. No-one is going to type that fast, so implementing an instant messaging system shouldn't be too much of a hog, and given that it would be an average figure... yeah, I think it could support some simple BBSs, and maybe basic pages (but don't put many images on...!). It wasn't that long ago that a "T1" connection was 1.3Mbit/s both ways...

JoshNH4H · 2013-11-23 01:24:16

GW- It's tough, of course. But I don't want to go too much farther than the horizon, so I actually don't end up with such unreasonable results. If I put my transmitter on the highest shelf in my apartment, it will be 7 m above the ground and a formula I found on wikipedia suggests that the geometrical horizon will be 10 kilometers away. Radio waves get refracted, so it could go even farther than that of course. There are some tall buildings right by me so that might block the signal some. If I can make a friend at the top of the 12 story building across the street from me, even the geometrical horizon is 25 km away. But we all know that radio signals can travel significantly farther than the geometrical horizon. Look at

Terraformer- It sounds like you know about as much as I do, which is to say that we have a lot to learn before we can even think of setting up any kind of network

GW Johnson · 2013-11-23 11:03:10

I know you can send encoded data over radio like that. I just don't have a clue how. But I've heard the varying hum of a carrier with data encoded on it, for decades on short wave radio. I know they have done it, as far back as the 1960's, and likely a decade or so before then.

GW

JoshNH4H · 2013-11-23 15:58:38

As you can imagine, they've developed a few ways to do it. These are Amplitude Shift Keying, Frequency Shift Keying, and Phase Shift Keying. Effectively, each one turns the frequency, amplitude, or phase of the wave into a binary signal. Simple but effective.

Terraformer · 2013-11-23 17:08:11

Amateur digital radio? Can you tune multiple aspects of the wave, encoding multiple bits at once? Not necessarily for actually sending more information, but for correcting it.

But yes, amateurs do use digital radio. I wonder, since that frees up a lot more space, could we get a lot higher bit rate? Maybe even 100kbit/s? Comparable with early widespread internet use, and definitely enough to support decent BBSs. Maybe even route the signal through voluntary nodes, to mask the origin...

JoshNH4H · 2013-11-23 18:35:15

My expectation would be that there would be nothing preventing triply keyed radio transmissions in terms of physics, but if we're looking at commercially available devices then that would probably represent a very significant increase in cost both for the receiver and transmitter. This is bad if you want the system to propagate.

Another thing: If you want the system to work like the Internet, it would have to involve two way communication on more than one band. The central broadcaster would also have to have an algorithm to broadcast pages as requests for them are sent.

What I'm thinking is a system with extensive local caching with a primarily one-way broadcast system. What you would have would be a central broadcaster (supplemented by as many rebroadcasters as want to involve themselves) continually sending out the totality of the information on the network, page/document by page/document. At the end of each document, any changes that have been made to the system in the interim can be broadcast. The changes can be recieved either through the Internet or, more in line with the systems goals, through a different band. This would be somewhat less strenuous than an Internet type system in terms of technological requirements and would have the benefit of making caching universal, theregore making the system recoverable.

I don't know about you, but if I accomplished half of the programming for that kind of system I would be extremely happy.

Terraformer · 2013-11-24 03:29:16

What about tracking changes, instead? Say, you have a copy of a page from 7 days ago, and request the new page. Rather than sending out the entire page again, the system (which will have maintained a log of all changes) sends out a file of the changes, which updates the local one. Think about it as storing the NewMars forums on your computer, and then only updating new posts when you refresh, rather than redownloading everything. Combined with a P2P system, so you can get the page from the nearest system with it...

JoshNH4H · 2013-11-24 12:00:36

Terraformer wrote:

What about tracking changes, instead? Say, you have a copy of a page from 7 days ago, and request the new page. Rather than sending out the entire page again, the system (which will have maintained a log of all changes) sends out a file of the changes, which updates the local one. Think about it as storing the NewMars forums on your computer, and then only updating new posts when you refresh, rather than redownloading everything. Combined with a P2P system, so you can get the page from the nearest system with it...

I'm gonna bring up the programming issue again. It's tough, especially if we're talking about a project between two or three people. Also, I don't think you're quite understanding how radio networks work. When you broadcast on a given frequency, the chances are good that everyone at least to the horizon can hear you on that frequency, unless there are a bunch of other people also using it, in which case there will be a lot of interference and data transfer will be exceedingly poor. However, for this kind of system to work, you need to specify a band for these kinds of communications, meaning that if you try to do a peer-to-peer network you're just going to turn your chosen band into white noise.

In terms of datarate, television signals can be sent over the amateur bands, so we can kind of take our pick (Digital TV is about 20 Mbps). In the interests of being a good neighbor (The FCC tends to get very unhappy if you are messing with other peoples' communications, even on the amateur bands. I'd say there's a fairly good reason to do so, insofar as they're supposed to be a shared public resource.) I would think we wouldn't want to, or need to, use more than 100 kbps down and perhaps 16 kbps up (1000 users typing at 120 words per minute is 12 kbps). 100 kbps is 12.5 kB/s, let's say you'll actually be able to use 10 kB/s. That's 1667 words/second. For comparison, it would take a typical novel about 39 seconds to be broadcast. If we're going text only, which seems logical to me, this should be more than enough. If our network manages to get to the size of Newmars (About 2 GB, I've been told), it would take 55.6 hours to broadcast. Admittedly, that's rather large (2 GB=335,000,000 words! I think a lot of these 2 GB are duplicates or pictures*...) But for my proposed architecture that would be the initial setup time and for the most part wouldn't be too important thereafter.

*With 116,084 posts on the forums as of right now, 335,000,000 words total would be 2900 words per post. I realize that I'm rather more long-winded than many of our other posters, and this post is 475 words including quoted text.

JoshNH4H · 2013-11-24 14:25:17

It occurs to me also that another benefit of my proposed system is that while you do need to be a broadcaster in order to make any changes or additions to the network, literally anyone able to set up the receiver and install the program would be able to access the network. This is a major benefit in terms of usefulness and reach.

JoshNH4H · 2013-11-24 14:31:27

It occurs to me that another benefit of the system I propose is that you don't need to be licensed at all to take part in it, because there's no limitations on who can receive transmissions, only on those who can send them. This would give the system a wider reach and make it cheaper for new people to operate.

Terraformer · 2013-12-31 08:39:43

Actually, what I have in mind is a mesh network, perhaps made like this - http://www.dd-wrt.com/wiki/index.php/Linking_Routers.

Add in a few "super-routers" every few hundred metres, or perhaps even up to a kilometre, that connect the meshes together into a bigger network. That's where the radio operators come in. Maybe we can use WiMAX for that. But if you just want to cover a small town with a network, you can probably just use off the shelf hardware and standards.

Of course, it requires an unbroken chain of routers to a super-router, but for most people, that won't be a problem. Perhaps we can even use a different band that's unlicensed, if it would interfere too much with existing systems. But I don't think that will be a problem.

To join onto the network, you'll just need to configure your own router to add to it. Perhaps the network can automatically assign a unique address when you download the software and first set it up? I'm thinking a two part one based on the local mesh and the super-router used to connect to the global mesh.

The end result, I hope, will be a system that's a lot more resilient to disruption, be it deliberate or accidental, and is a lot harder to censor. It would be by nature peer to peer, and I expect local caching would be used extensively (storage is a lot cheaper than transmission; a terabyte only cost about $30 last time I checked, so whatever passes for the local hackerspace/library/anarchy port can probably afford to cache the most common stuff accessed, not including peoples habit of never deleting anything they download).

JoshNH4H · 2014-01-01 11:12:38

Well, that's quite ambitious. Haha. Having said that, you really do need an uncensored Internet there in the UK. Have Sealand do the broadcasting perhaps?

Terraformer · 2014-01-01 11:34:04

Eh, we need an uncensored internet everywhere. The system I propose would be a proper internet, being a network of networks. Accessing something on the local net shouldn't take that long, needing only a few hops to go a couple of kilometres (using maxed out WiFi, at 500m range), but to get something from another network will need to go through a bridge, probably using ham radio. Lower data rate though. Code has to be very efficient.

But it has to be a network anyone can join. That's where most prefixpunks have gone wrong. Hardly anyone will want to use free and open source technology if they have to spend ages fiddling with it to get it to work. But if it's a question of buying a device and running a setup wizard on it, then leaving it be, they'll be a lot more open to joining the networks.

JoshNH4H · 2014-01-02 00:45:22

Well, no argument. You could probably get it to work with extensive caching. The issue that I can see is that it's hard to get going, so you may want to start it off so that the wifi/wimax routers improve performance on top of the ham radios, which have longer range.

Terraformer · 2014-01-02 05:27:41

Well, if you're aiming to create a local wireless network, you probably don't need to actually involve ham radio, not if you can get enough people to set up routers. Ideally, the central server (containing a BBS and links to other peoples sites on the net?) would be located at the centre, to minimise the number of hops required. We could use WiFi, which has the advantage of being off the shelf - and there are already dedicated devices for setting up such networks available (to increase the access to a DSL), so it would be mainly a programming exercise I think. Or we could use some of the non-licensed bands, which would require more effort but which would make it entirely open source.

If we could get a system like that set up, I'm fairly certain someone will try to use Ham radio to connect two of them together.

Of course, if it gets big enough, you'd probably be able to crowdfund the purchase of some radio spectrum for running it...

Terraformer · 2014-01-02 08:40:09

Naturally, I'm not the first person to suggest such a system, nor would I be the first to implement it - https://en.wikipedia.org/wiki/Wireless_user_group. Though I'd like to move away from the use of IP addresses in the system, towards a decentralised assignment system.

I've had a look at available frequencies in the UK, and it seems to be possible for Ham radio to be done using the microwave spectrum. So running a system of microwave links between meshes may be feasible... the aim of providing 100kbit/s to everyone on the network isn't looking too daunting...

100kbit/s is ~2000 words/second, so you could download the entirety of Worm in under 15 minutes. Unless someone else on your local network already has, in which case you'd be copying from them at a much faster rate...

JoshNH4H · 2014-01-02 11:33:35

I don't think microwaves are good as a ham radio frequency because they're absorbed by water vapor in the air. But perhaps I'm mistaken on this?

Terraformer · 2014-01-02 11:50:06

Well, they're not good if you want to talk to people over long distances. But for connecting mesh networks together, they're great - microwave links such as WiMAX are used as part of the internet's backbone. We could perhaps get 10-20km with them, at gigabit speeds; no good if you're living more than that distance away from a router, but most people won't be. The bigger problem would be getting permission to set the routers up (people are a bit funny about microwaves, and often, those people are in government). But we don't even need to go 10km, probably no more than 2km, so we might be able to mount them in places that are already somewhat high up (church towers, perhaps?).

I can definitely see speeds of 100kBit/s being feasible. Maybe, after the system has been operational for a few years, with people improving it all the time, we'll start to get back to modern internet speeds.

Encryption as standard, of course. Possibly onion routing as well.

JoshNH4H · 2014-01-02 12:22:20

Sounds like you need to start an open source project. The outrage is there, I bet, to set something like this up.

Terraformer · 2014-01-02 14:18:50

Well, I see myself as being more of a Satoshi Nakamoto - outline the basic standards and system, do a bit of work, and then retire out to work on something else whilst other people further it. Just maintain my local super-router and cache. I'm sure Wikipedia won't mind their most popular articles being cloned. But I would hope people would start to add new content in. For a small website such as NewMars, you could just use the standard data rate; if you were working on something like Wikipedia, it would make sense to stick a super-router in.

Or maybe I'll come back in, if it takes off, to work on something like a telephone system using it (VoIP, except the addresses won't be IP).

I don't know what data rate would be achievable using available frequencies. If we get the same efficiency as WiFi, of over 400baud/hz, and a bandwidth of 0.5GHz (if you can push the boundary between microwave and far-infrared, you can gain access to 10GHz bandwidth as a ham, but there's a good reason why those frequencies aren't used by anyone else... still, if the relays are close enough together...), then that would be a connection of up to 200Gbit/s. Eh. Getting extreme there, you'd be starting to compete with superfast broadband... which is why I set that as a middling goal.

New Mars Forums

Announcement

#1 2013-11-22 10:39:46

Amateur Radio!

#2 2013-11-22 12:39:40

Re: Amateur Radio!

#3 2013-11-22 15:19:17

Re: Amateur Radio!

#4 2013-11-22 16:29:13

Re: Amateur Radio!

#5 2013-11-22 17:36:23

Re: Amateur Radio!

#6 2013-11-22 17:45:01

Re: Amateur Radio!

#7 2013-11-23 01:24:16

Re: Amateur Radio!

#8 2013-11-23 11:03:10

Re: Amateur Radio!

#9 2013-11-23 15:58:38

Re: Amateur Radio!

#10 2013-11-23 17:08:11

Re: Amateur Radio!

#11 2013-11-23 18:35:15

Re: Amateur Radio!

#12 2013-11-24 03:29:16

Re: Amateur Radio!

#13 2013-11-24 12:00:36

Re: Amateur Radio!

#14 2013-11-24 14:25:17

Re: Amateur Radio!

#15 2013-11-24 14:31:27

Re: Amateur Radio!

#16 2013-12-31 08:39:43

Re: Amateur Radio!

#17 2014-01-01 11:12:38

Re: Amateur Radio!

#18 2014-01-01 11:34:04

Re: Amateur Radio!

#19 2014-01-02 00:45:22

Re: Amateur Radio!

#20 2014-01-02 05:27:41

Re: Amateur Radio!

#21 2014-01-02 08:40:09

Re: Amateur Radio!

#22 2014-01-02 11:33:35

Re: Amateur Radio!

#23 2014-01-02 11:50:06

Re: Amateur Radio!

#24 2014-01-02 12:22:20

Re: Amateur Radio!

#25 2014-01-02 14:18:50

Re: Amateur Radio!

Board footer