Shortwave HF Station: Filling in the gaps

branko · 2014-11-08T07:38:22.104Z

Ben:

Support for general file transfer would let just about any technique transfer the database.

Outernet transfers files, nothing else. What happens with those files later is completely up to the user. Librarian is just one way of working with them. It’s not even required to receive Outernet’s signal.

Ben · 2014-11-08T11:11:22.869Z

KR0SIV:

isn’t the entire idea of outernet to bring information to people without internet access?

Yes, it absolutely is. I was thinking that there may be places with informal network structures or ham radios that could complete the puzzle.

branko:

Outernet transfers files, nothing else.

Is there somewhere online they can be pulled from?

branko · 2014-11-08T19:29:39.048Z

Ben:

Is there somewhere online they can be pulled from?

Yes, from here. The !file_list.txt doesn’t list all the files, though. I haven’t gotten around to having the server monitor this folder and regenerate the file.

KR0SIV · 2014-11-10T20:27:34.980Z

I would be happy to write some simple software to demo this, it could grab data and transmit it at pre-configured (or imediate) times.

Is there a way to grab the data that would go out without having access to a dish? I could setup a recieve station I just don’t have the money for the DVB reciever or a place to mount my dish at the moment.

Ben · 2014-11-11T04:07:43.152Z

KR0SIV:

Is there a way to grab the data that would go out without having access to a dish?

branko:

Yes, from here.

Im learning python and am in the middle of writing a short script to download the data base from here for android.

cj5 · 2014-11-11T06:38:52.134Z

Hi all. I am a licensed ham operator (KJ6BBS), and I can provide some pointers and ideas. First, if you are considering shortwave as some kind of source for digital data, you should consider utilizing multiple transmitters/receivers across the globe. Us Hams use technology called packet radio. It is limited in range, but if you utilize multiple transmitters/receivers throughout the globe, then packets can be easily relayed. Second, another factor to consider over long distances on HF is measuring signal integrity over propagation. Whenever I prepare for working stations around the world, I always check several resources for signal reports, one of which is a digital mode called WSPR (http://wsprnet.org/drupal/). The neat thing about this, is that you can listen for a station or stations anywhere in the world, receive a signal strength report, and the app will upload reports to others on who is heard or being heard. Applying this to outernet, receivers could ping this network of transmitters/receivers and use that data to acquire the optimal signal or transmitter location. In the past this has been done using modes like ALE, which is pertinent to this case.

Anyhow, that’s my two cents. I would love to contribute to this project if I can. I have a background in library and info science, a license in amateur radio since 2009, and I also am a professional programmer, so this project is perfect! look forward to talking more about this.

KR0SIV · 2014-11-11T14:27:11.149Z

Great idea cj5, we could implement something along the lines of wspr directly into the protocol for this software what would allow us to understand how and were we are propagating, we could even setup a dedicated page to show the propagation of our radio network.

I believe it would be a good idea to have hams involved even if we get a large SW broadcaster to work with us, they don’t propagate everywhere anyway. Likewise would could have a SW station send out some prop data for us as well and add it to the map.

Syed · 2014-11-11T16:45:35.277Z

This might just be one of my favorite threads so far. I’ll try to make this a comprehensive post, but I’m sure I’m forgetting something, so feel free to ping me if I do.

Shortwave is important–really important–and it will definitely be a part of Outernet’s multi-frequency approach. Although the precise frequency list is not yet available, reception of Outernet by a receiver with multiple tuners will likely the following bands:

Ku-band (downcoverted to L-band by an LNB)
L-band
UHF (around 433 MHz)
Shortwave (2 MHz - 30 MHz)
MW/AM (500 kHz - 1700 kHz)
Carrier pigeons

As you may have noticed, Outernet has no allegiance to technology, infrastructure, or modulation scheme. Our goal is to build a universal information service that is accessible to all of humanity. We use whatever hammers and shovels allows us to do this is the fastest and most cost effective way possible.

Surprisingly (at least to me), broadcasting bits by satellites is considerably cheaper than doing the same over a 100 kW shortwave transmitter. The largest private shortwave installation in the country, WRMI in Florida, is very keen to work with Outernet, but we still need to work through the issue of cost, considering that it will take at least four antennas to delivery a global MB. And 100,000 watts of power is a lot of electricity.

If anyone is curious, we would not be using DRM with these transmitters because high-power DRM exciters are actually not available for purchase. Instead, we would essentially be broadcasting audible noise that can be demodulated by even a feature phone. We think it’s possible to manufacturer a $10 audio jack receiver, which would feed the signal to a simple Java app. The benefit of this approach–which is just one of several for shortwave–is to allow feature phones and existing consumer-grade shortwave radios to receive the signal. The downside to this is the bitrate: 60 bps. But over the course of a day, that’s 500 kB, or an entire ebook.

To learn more about this approach, check out the work of Dr Kim Elliott at the VOA. http://voaradiogram.net

To be clear, Outernet is in no way affiliated with VOA. We’re just pointing out some very interesting research that is being done there.

But like I said, this is only one path–and all other paths are definitely on the table.

Syed · 2014-11-11T16:45:53.462Z

cj5 · 2014-11-11T18:19:54.579Z

Indeed, this is my favorite thread as well.

I had no idea you guys were teamed up with VOA. I know that Florida station very well, as I hear it all the time from California. Granted AM transmitters are expensive, and is the main reason why they are not used as much anymore as a broadcast medium, the delivery of data could be cheaper if the data was distributed. Maybe because I am excited to hear that there is an opportunity for shortwave radio to have a place in a modern application, that I am biased towards utilizing it, but I have to agree with @KR0SIV, that SW radio would be a great way to complement the entire Outernet network.

A lot of Hams I communicate with use packet radio, ALE, WSPR, JT65, PSK31, RTTY, and various FSK modes to communicate, and these would be great modes to use as an exchange. In other words, these modes, since they can’t handle lots of data in a short amount of time, would be great for simply supplying a user’s receiver with a status of the network. If propagation does not allow for optimal conditions, supply the receiver with satellite information to link up. If conditions are good enough to go over SW, have the receiver link up to several SW stations. This group is doing a lot of work already in this area http://robust-packet.net/ and the Robust-Packet is a lot faster than HF packet.

What is Outernet’s goal with having a single ground-based transmission point? To me that seems that we’d be limiting ourselves to a single source of transmission, and that’s not what the mission is, right? Ground-based transmissions would not need to derive from a single source, and would not require anywhere near 100kW output. I’ve worked QRP (low power voice and data transmitting) in Ham radio, and you would be surprised what even 2.5 watts could do. If you planted a small unmanned station in each US state running at 100 watts, supplied by a small solar or wind power source, you could easily get data anywhere within North America over HF. Using an AM radio stations infrastructure from a single point with that much power is unreasonable.

Satellite sources are just as important to a well engineered network, but let’s not depend too much on one thing, like you said. Obviously, UHF, L and Ku bands can deliver more bandwidth over a single source, but going with the theme of not having to depend on a single tech infrastructure is the smart way to go, and utilizing as many technologies as possible to perform one task or various ones would definitely be a benefit to Outernet’s vision.

Thanks, for sharing that information.

Syed · 2014-11-11T19:17:20.675Z

cj5:

I had no idea you guys were teamed up with VOA.

To be clear, we have no official working relationship. But they are aware of us and we are aware of them. And I’ve spoken with Dr. Elliott to learn more about what he is doing with existing transmission equipment, cheap shortwave receivers, GFSK, and the open source fldigi

cj5:

What is Outernet’s goal with having a single ground-based transmission point?

The goal is to simply have a global beacon–exactly as you described. It would be ideal if there was a permanent channel that could relay basic system information. If we can do that exact thing at lower cost and better quality of service with a truly global ground network of lower power transmitters, then all the better!

cj5:

I’ve worked QRP (low power voice and data transmitting) in Ham radio, and you would be surprised what even 2.5 watts could do.

How about those qQRP guys? Bouncing signals across the world from and Altoids tin and less than 1W!

Satellite sources are just as important to a well engineered network, but let’s not depend too much on one thing, like you said.

In my dreams, we have autonomous, solar-powered, sea-faring whitespace multicasters. Those broadcast bots are in addition to backpacks on pigeons.

Trevor · 2014-11-11T20:09:47.155Z

Kind of like Firechat for ham radio.

KR0SIV · 2014-11-11T21:45:43.017Z

The nice thing is that a lot of amateur based digital radio modes already have decoders available for both android and iOS. This would allow anyone with a cheap shortwave reciever and a cellphone/tablet to decode our transmissions.

That being said of course a raspi, computer, etc can do this as well.

It would be great to have a SW station for primary SW broadcast, however in addition hams could use the 30meter band (a 10mhz digital only no contest band) to relay the transmissions in parts of the world the major SW station can’t hit.

Hams could also transmit more frequently on a volunteer basis without the cost of the broadcast station.

Trevor · 2014-11-11T22:24:53.821Z

Would it be possible to use this band to extend the range of a local Pillar?

Syed · 2014-11-12T01:37:35.797Z

Can you describe your scenario in a little more detail? I want to make sure I understand it correctly.

One thing to remember, though, is that shortwave just can’t propagate the avalanche of bits that Ku-band can.

KR0SIV · 2014-11-12T09:00:33.649Z

Indeed, we’re talking 300 baud here… more or less depending on the mode and if we use error correction.
So a condensed version would likely be needed for SW/HF

cj5 · 2014-11-12T15:36:19.589Z

@KR0SIV yes! Hams have been busy building their own decoders for many years. =)

I was thinking more along the lines of automating this. If you are aware of the COTHEN system, it has manned stations as well as a majority of unmanned automated relay stations (nodes). I think at most you would need a controller software that would respond to smaller message packets like an ALE call (i.e. similar to WSPR, JT65 modes), and that receiver could ideally push/pull data from the Outernet, and serve info to receivers in the field over a more robust mode (this probably is similar to internet network hubs). The onsite automated stations would house a receiver/transmitter for controls, a receiver/transmitter for data, a tower, an power source, and possibly a file server that mirrors whatever data a primary station sends (this way there is no need to wait for data to be received from the “mothership”, and then be sent to user’s receiver).

The 30 meter band would be a perfect spot to test on.

KR0SIV · 2014-11-12T18:12:47.200Z

I hadn’t heard of the Cothen system, sounds interesting.
It might also be beneficial to have hams setup UHF/VHF nodes in their towns that transmit data pulled from the outernet satellites or the HF modes.

So for example I could have a receive station in my town with a VHF rig about 200’ up on a tower that could then transmit this data over AX25 (much faster mode) where the range could be increased to cover several counties or in the case of using the 6 meter band possible the whole state.

cj5 · 2014-11-12T18:52:54.900Z

Yes. Exactly. These set ups could be leased too (similar to leasing solar panels and wind generators to power agencies). Rent would cover maintenance and such by the amateur radio operator. I would think these stations would be great for being primary nodes to/from satellite based data. I like the AX25 idea.

I know of the COTHEN system because of my experience with using Ham ALE (http://hflink.com/). If you have the proper antenna configuration, a quick tuning apparatus, and a radio, establishing links can be done. This allows for optimal conditions depending on which band propagation is favoring. Using the data modes like packet is great because the system will tell you if conditions are getting worse, data will stop, the software will QSY the radio to a better band, and data will pick up where it left off. I assume COTHEN works in the same fashion.

Syed · 2014-11-16T02:59:17.014Z

What is the total cost of a cheap, long-range and autonomous node?