cOMMUNICATIONS OPTIONS?

[daybrown]

Out in my neck of Ozark woods, the only high speed bandwith option is satellite. the hardware is expensive, the monthly service is 50$ or more per month, and the speed sux. Hughes.net mite be a little faster than wildblue.net and the higher power punches thru rain better, but no VPN and there's problems with Linux.

Before that, I tried the long range wireless at 900 mhz, which worked... until the forest leafed out. Folks out here need a wireless link with a wavelength longer than wet pine needles. 400 mhz on down. And if you down in a canyon by a nice fishing hole, then 100 mhz or less. Nothing else will go over a ridge much less dip into the valleys.

Course, the ham operatators suggest packet radio. That's 9.6kbps, compared to 56k dialup. Helloooo?

Like steep forested mountainous areas all over the planet, there's lotsa dead zones with virtually no FM/VHF/UHF reception. If the population density was higher there'd be closer transmitters, but then they'd bring in the cable. With farms that average 200 acres, that'd be 1/4 mile of buried cable per user. Or more if there's an area of national forest.

But then, I thot of an RF tank circuit with the coil center tapped. No sin wave, no carrier, much less an IF. just a series of pulses, pos for zero, neg for one, with dead air for the stop bits. Since data varies so much between pos/neg, it wouldnt look like a sin wave, and regular tuners would ignore it. And with tuned Yagi on each end, say 12db, prolly get 15 mi on 5 watts, 50 mi on 20 watts.

Seems like I read about pulse detectors that'd pick up on it. A modern version of the 'spark transmitter' used on HMS Titanic. This seem reasonable?

 

[Sceadwian]

In isolated areas you don't have much in the way of options. You can not transmit high bandwidth RF communications over low frequencies without breaking multiple laws due to the distance those frequencies can travel and the number of licensed users of those frequencies that it would displace. You're talking about a couple of dozen users displacing thousands of licensed users. Laser communication might be an option but snow/rain can effect that and it only works from line of site. A 5 watt signal might only give you 15 miles of valid signal, but the noise floor is going to be raised 10 times that distance or more, depending on the frequency and propogation methods.

 

[daybrown]

Pulse wave.

Maybe I'm not as clear as I hope to be, but no way would this interfere with the licensed bandwidth of anyone. Its not a *sin* wave. None of the tuners, which would not be hooked up to a tuned Yagi anyway, would lock on to it. PLL would not see it because of the *phase* changes every time the signal went from a zero to a one.

Laser wont penetrate the canopy either. Could you clarify what you mean by 'propagation methods'?

What I have in mind is not 'one size fits all'. Thats for where you have clear line of sight.

If you drive up us65 from Leslie to Marshall AR, and hit 'scan' on your FM, it'll stop at the Christian fundy station in Marshall, no more than 8 miles away. Hit scan again, and after 20 seconds or so, it'll find.... the same Christian fundy station. There are stations in Little Rock and Springfield MO that put 100k wats on a channel that dont get here. How is 5 watts here going to do anythiung to them?

There are fringe areas like this all over the planet. The dozen users you mention are not enough of a market to waste the watts trying to reach. They are not enough to be worth burying cable. and they are not at all interested in cutting trees down to create a clear line of sight. Besides, lots them live down in the valleys on trout streams. They can fish off the back porch. They like that, and they'd like to get online too.

There is a way to do this that wont piss anyone off. Besides, the FCC does not run the planet; there are lotsa remote rural areas who'd like to have this. Its time consuming to put up a yagi, but lotsa poor folks would bother to provide online education for their kids.

i am worried that the Yagi itself would have some resonance. But at this low wattage, it'd be easy to stick the transceiver in a cigarbox and mount it right on the antenna, and eliminate all the harmonics from a cable. Something with extremely short VSAT mite be needed seems like some MOSFETs are nowadays, but I havent worked with them outside of SMPS or DC-DC. Then, last nite, I was reminded of SCR; but if anyone has been tinkering with waveforms, I'd like to hear what they had to say.

Another issue I've wondered about is whether a Yagi could have both a driven and a driver element, with the driver acting like a reflector at the base with a less steep pulse rise, while the remote has the opposite with the less steep pulse on a director. Otherwise, I havta put up two yagis for full duplex.

 

[Nigel Goodwin]

Maybe I'm not as clear as I hope to be, but no way would this interfere with the licensed bandwidth of anyone. Its not a *sin* wave. None of the tuners, which would not be hooked up to a tuned Yagi anyway, would lock on to it. PLL would not see it because of the *phase* changes every time the signal went from a zero to a one.

To transfer broadband it would be a high power wideband signal, it would interfere with a huge range of licenced frequencies, and would be HIGHLY illegal.

 

[Sceadwian]

The transmit method you're talking about would put out a large amount of unwanted RF on every frequency the data stream created, just because it's not a sine wave and doesn't have a carrier doesn't mean it's not creating noise and RF energy in unwanted spectra, especially if you're feeding it a square wave. And what I mean be propagation methods is low frequency RF signals (bellow the FM radio you're using as an example) follow the curves of the earth better and will go into valleys and up over hills. You're basically talking about directly modulating a broadband carrier between 1 and 20mhz or so. Aside from the fact that you would need very large broadband antennas on both ends to do the transmit and receive, even low power transmission could travel incredible distances. HAM DX'ers use these frequencies a lot because the signals will actually bounce off the earths ionosphere and transmit over the horizon.

 

[Qrpmonk]

I am also remote country with dial-up and the only practical way for now. One thing being worked on is a thing called BPL. It is a technology based on broadband over power lines.
Hams are really up in arms over the trials being done in some test cities claiming interference, but clearly, if there is such interference I bet they will find a way to resolve that.
BPL would give a huge segment of the worlds population a way to have fast service at hopefully a low cost.
What a world changing solution if this could be developed so that anyone with electricity could have broadband.

 

[Sceadwian]

There is no way of resolving the problems with broadband over power lines Qrpmonk, it's high frequency broadband communication over miles and miles of wire, there is no way to prevent the wires from acting as antennas and transmitting the signal into the air, and at even halfway decent speeds a couple hundred feet of wire will be a VERY good antenna. I hope sincerely that it never gets anywhere. If it ever becomes wide spread I'll be the kind of person that will go around tossing bolo style RF chokes onto power lines to kill the signals.

 

[Aloefundi]

In ZA there has been much talk of BPL of the last few years with the slow introduction of of a second Telco operator. We have had many roumours whith various theorys being bandied about.

However the route that is taken in ZA is as follows. Fibre is either strung along existing powerlines or the fibre is actually wound within the existing power cables. The key is that the data stream is via optic within the power line and not the physical powerline itself. So as for BPL the question is "Whats your definition?"

 

[Nigel Goodwin]

In ZA there has been much talk of BPL of the last few years with the slow introduction of of a second Telco operator. We have had many roumours whith various theorys being bandied about.

However the route that is taken in ZA is as follows. Fibre is either strung along existing powerlines or the fibre is actually wound within the existing power cables. The key is that the data stream is via optic within the power line and not the physical powerline itself. So as for BPL the question is "Whats your definition?"

This was done years back in the UK, with robot machines spinning fibreoptic cables along the high voltage wires on the pylons. However, this is only for backbone, not for individual connections - BPL uses the power lines to transfer broadband directly into the home via the existing incoming mains wiring, actually using the same copper - in a similar way to ADSL piggy-backing on the phone lines.

As already suggested, it's a seriously bad idea - and will radiate interference over large parts of the RF spectrum, as such it hasn't gained any popularity.

 

[j.p.bill]

Don't feel too cut off - I'm up in southern Cooper County and am just out of DSL range. There's no alternative. We've been on a list for assymetrical satellite for 18 months with no action. I volunteer to help with the computers at a public school, so I can get downloads on their T1 line. Even there, I see speeds from over 1 Mbit/sec to 39Kbit/sec. As long as the profit margin governs every aspect of life, it's just going to stay like this.

 

[mneary]

We live in different areas for different reasons. Profit is maybe the reason that you can't get broadband in rural Missouri. It looks like your area has fields ranging from 50 acres and more.

The same profit motive is why I have DSL in the suburbs of Los Angeles but can't afford a 100-acre backyard.

 

[Oznog]

Like people say, you can't possibly get away with an unlicensed transmitter. Not only is it illegal, you lack the necessary understanding of radio transmitters to do something this powerful.

In fact I think it's worth pointing out that if you had understanding of radio transmitters, you might determine that transmitting over this distance without a clear line of sight is impractical.

There are web pages documenting people's attempts to run broadband over HUGE distances even with commercially available routers, using well designed, highly directional antennas and a clear line of sight.

I wouldn't dismiss the idea of running cable. If you can somehow find the cable cheap and know how to use it, it'd be a hack system but still do the job.

Or, directional towers and a line-of-sight with either a central tower or even hopping from neighbor to neighbor may be the only other way. I know you will say "this is not as cheap and practical as I wanted" but this really is a difficult task and a shortcut to get performance without complexity and expense may simply not exist.

 

[Aloefundi]

Hi Nigel

100% Correct, most of the powerline transmissions are for backbone only. The buzz running around the industry here was that they wanted to provide trippel and quad play to users with an IP termination via a wall outlet in the home, however as previous posts have explained RF bleed is an issue. This was tried in one of our local municipalities (Tshwane - Pretoria) however it worked quite well until they added a large number of users then it fell over.

There is a Swiss company (forget the name) that is developing/developed a similar technology but for internal use on small installations using the electrical wiring within the home as a LAN. this would still require a conventional external DSL connection to the ISP. I undertand that it works along the line of a hub and not a switch.

The next best options are 3G (4G to come soon) EDGE, GPRS or HSDPA for mobile apps if you have coverage, or if fixed the WIMAX technologies. WIMAX uses 802.16d, which is only for fixed installations. However the newer (not ratified) 802.16e with be for mobile WIMAX, thats the one to wait for but you still need coverage for it to work.

We have done a few WIMAX installation in Southern Africa where a single WIMAX tower providing a small town with broadband. However shared resource/service issues still apply.

 

[Aloefundi]

Hi Nigel

However the newer (not ratified) 802.16e with be for mobile WIMAX, thats the one to wait for but you still need coverage for it to work.

Sorry 802.16e Has been ratified by the IEEE

Aloefundi

 

[gramo]

As already suggested, it's a seriously bad idea - and will radiate interference over large parts of the RF spectrum, as such it hasn't gained any popularity.

I thought that was just a roomer someone started? Is it actually true?

 

[Nigel Goodwin]

I thought that was just a rumour someone started? Is it actually true?

As far as I know it is, certainly sticking RF down the power lines is going to radiate somewhere!.

 

[Sceadwian]

Gramo, think of the length of a wifi antenna. About what, 4-6 inches? Power cables are not shielded, which effectivly makes them an antenna. Now attach something that is capable of wifi speeds to it. Bad things happen =) I wined about this extensivly in a previous post a few months ago. Even if you share a common branch network to 10 or more homes the harmonics you're going to create from the mismatched transmitters extend well past even the maximum bandwidth of the lines because it's a digital signal. Every single user bleeds out that much more of a percentage of the bandwidth they have available, regardless of weather or not it's used. At human scale ranges even time dialation effects on clock phase bleed becomes an issue, and that doesn't include whatever universal or freak capacitive or inductive reactance that is native to the local system. Makes over the air RF look simple, and most people die without ever understanding that on anything more than the most trivial of levels.

 

[ex-navy]

Set up a wireless bridge

A common practice as we did in the military is to set up a wifi bridge.

It's a simple wifi repeater system, (leap frog) using 2 or 3 seperate routers.

For example, from the ISP provider's last ethernet point, install a Linksys router with a yagi antenna pointed in the direction of your home.

Have that router set up with DHCP disabled and assign only one static IP address. This will be the IP address of the next station.

This is the transmitter router.

Install another Linksys router with a directional yagi, pointed in the direction of the transmitting yagi.

Set up the 2nd router to use the DHCP and have it's IP address as the same as the one assigned by the transmitter. Set up the DHCP so it only assigns two IP addresses. Take the ethernet cable out to a 3rd router. This will be the last one.

Using a yagi off of the 3rd router, point it at your house. Assign an Ip address that was one of the 2 from the second router.

The 2nd Ip address will be your house wifi units.

I think you might get the picture of what is happening.

If you have to do 2 hops, you need 3 routers, 3 hops, 4 routers, etc.

This is the same as we used in the Navy for satellite hopping.

The routers do not need to be 2.4Ghz Wifi, you can mix and match from 2.4 or 5 GHZ ISM bands.

 

[Super_voip]

As each router is "store and forwad" the baud rate drops with each hop.
The BPL option is very bad as the power lines are very unbalanced cable as there is an earth connection to the neutral wire every couple of poles, having said that I'm applying for a job with a power provider to investigate just this option.
On a positive note there are some long range data transmitters available. I have been using NextG modems (850MHz HSPDA WCDMA) from a telco which will have a data speed of 22Mb available this year and 42Mb next year. I think this is equivlent to WiMax but I haven't really looked at WiMax as it isn't available here.