May 30, 2008 at 10:08 pm #2749
Ultrasound is nto feasible for long distance data connections. The bandwidth is too low and there is too much noise to signal ratio.May 31, 2008 at 2:39 am #2757
An option for over-the-horizon communications is to bounce it off the troposphere. This is sort like two guys communicating by shining lights on clouds, but instead of lights on clouds it is microwaves on the troposphere. I imagine a link from Anguilla (where I live) out to a floating community in the Sargasso Sea.
There are groups working on blimps and UAVs for communications relays. I think there will be off-the-shelf products in a few years.May 31, 2008 at 8:49 am #2764May 31, 2008 at 9:25 am #2768
Might be fun to go to the “basement” and shout to your neighbours 300 meters away, who could answer the same way. As an emergency communication method it might have some usefulness – the universal wirephone of the seaMay 31, 2008 at 9:30 am #2770May 31, 2008 at 9:32 am #2771
We use VSATS. They are the ones I was talking about. Tens of thousands per month for fractional T1. One dish, transmit and receive to the satellite, not receive from satellite and transmit via phone or ground station. they are effective in places with no infrastructure, and not too terribly difficult to set up and maintain, but the bandwidth on the satellite is bloody expensive.June 1, 2008 at 11:38 am #2801
Note: TSI could easily become a shore station dedicated to Seasteaders, and as noted by some of the existing commercial providers, this could be spun off into a for-profit business at some point.June 2, 2008 at 6:31 am #2837
Cool. It looks like there’s some kind of Sat coverage almost everywhere.
On another note: is AX.25 as easy as it seems?
Heres what I did…
1. I apt-got the relevent packages
2. ran `soundmodemconfig`
3. set both modulation both ways to psk (i have no idea if this is ideal, it just looks familiar from my reading)
4. flipped through the possible sound card settings until the scope started wigging out
5. Entered bogus callsign
6. ran `soundmodem`
…and I get this…
sm0 Link encap:AMPR AX.25 HWaddr QWERT
inet addr:10.0.0.1 Bcast:10.0.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:256 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
All it’s hooked up is my headset, so there’s no meaningful signal going into it.June 2, 2008 at 6:57 am #2839
It’s pretty easy. It’s just got limited usefulness, with the low speed/bandwidth. But “useful” depends on where you’re standing. When a lion is standing in front of you, a rock is better than a bare hand, and a gun is better than a rock. It’s all relative. Want email someplace where better solutions are not available? I’ll take the slow route over nothing.June 2, 2008 at 7:59 am #2841
It just dawned on me that even when satellite is running full boar, routing DNS thru AX.25 will make the satellite latency a lot more tolerable.
imagine being on sat and the dns requests are cascading so to speak… dns request, page loads necessitating another dns request and so on
Of course there are a lot more tricks that can be employed…
RSS – so browsing for news and whatnot can at least seem instant
Cache of Wikipedia.. it’s only like 7 gigs or something. bummer that they don’t let you get the images anymore though
precrunching jpegs like the so called accelerators doJune 2, 2008 at 9:54 am #2843
You would definitely want a caching proxy server, no matter what. HF is not a great format for web browsing. I can be done if the site you’re browsing doesn’t use file that are so big they time out downloading. But it’s primarily a text-based system. It’s excellent for data like weather, text-email, GPS, etc. Theoretically, yes, you can run different services through different gateways- DNS requests over HF AX.25, or even HTTP requests which then download from Satellite. The implementation is a little tricker. You’re not going to beat satellite latency that way though.
June 2, 2008 at 3:45 pm #2858
- HF is far lower bandwidth than the high frequencies used by satellite
- You’re still bouncing a light-speed signal off the ionosphere and around th world to a ground station. Not quite as far as a satellite, but not close either
- You’re going to get more re-transmits due to signal/noise ratio
How can I get a real AX.25 connection going?
I was thinking that I could just feed sound from one box into the other. I have a two identical servers I could wire up. Will this make my soundcards asplode?
Or, can I just (cough) point the Speaker A at Mic B and Mic A at Speaker B?
Google didn’t give any hints.
If it works, I’m gonna move on to bonding via `ifenslave`, it looks really easy.
Here’s the example from the manpage…
# modprobe bonding # ifconfig bond0 192.168.0.1 netmask 255.255.0.0 # ifenslave bond0 eth0 eth1
Edit: and I don’t think bonding has much ,if any, overhead. It just does round robin on the interfaces, therefore I think it will work with AX.25.June 2, 2008 at 3:48 pm #2859
I’d go for mobile cellphone technology instead of HF. It’s mature and has decent bandwidth, and is especially easy to set up in a flat and open environment such as the ocean (no more expensive refraction / reflection study for placing the stations and setting up their respective power). Of particular interest is the radio uplink technology used for connecting the cell stations, they have huge bandwidth and, too, are very easy to set up when the view is devoid of obstacles. However they would require tracking equipment in order to compensate for movement.June 2, 2008 at 5:16 pm #2866
What about using a combination of GPS linked in with the locations of friendly seasteads (or even boats) and radio transmittion (or even the optic option discussed earlier). The satellite would configure the shortest, most energy effective route between friendlies to the desired end receiver, and the message would be sent through this series of seasteads to the end location. It would be less energy intensive and cheaper than sending from point A to point B I would think. A big downside would be the perceived loss of autonomy and independance but sacrifices are going to have to be made sometimes.
I hope that made sense.June 2, 2008 at 5:50 pm #2867
That’s basically what 802.11s is.
The reference implementation is finally going somewhere.
When it starts to mature, it won’t hurt one bit to add it to everything else!
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