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Old 05-12-2011, 06:34   #1066
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Re: Long-Distance WiFi Device

There are two parts to any successful WiFi system - first is reception of the signal from the shore based system. This is pretty much a factor of the type antenna you are using.

- - Built in WiFi in your lapbook/netbook/etc. uses an extremely small wafer type antenna usually located at the hinges of the display. External antenna vary from "rubber ducky" omni-directional sticks of various "db" ratings. Then there are corner reflector and even highly directional "yagi" antennas that look like horizontal tubes.

- - The receiving antenna is rarely a limiting factor as the shore based systems involve rather powerful transmitters. What you see on your "signal meter" is normally just the strength of the shore based system transmission.

- - What is the most limiting factor is the "return signal" - that is, the signal your computer sends back to the shore based system. Since WiFi is a "2-way" system, like a VHF radio - your computer or antenna system must be powerful enough to broadcast a signal back to the shore based system.

- - Built-in WiFi in portable computers average around 50 milliwatts or so - that is really a weak signal and as I am sure you have noticed you need to be really close to the shore based system be it in an internet cafe or marina.

- - Over the last year or so, external "powered" antennas have really come up in the world with transmitting power increasing from a couple hundred milliwatts and up to as much as 2000 milliwatts for the pure USB powered systems. Besides the raw power increase put out by the powered antenna systems, their use of high "db" antennas seems to effectively also boost transmission range - or at least they claim.

- - The original RadioLabs systems were about 400 mw; the Engenious EU362 is listed at 200 mw; the Alfa systems come in 500 mw, 1000mw, and 2000mw. Generally the more milliwatts the better, but you can also use antenna db to increase effectiveness. So a lower milliwatt system with a high db antenna may perform as well or better than a larger milliwatt system with a low db antenna.

- - Amongst the many variables overlooked is the fact that WiFi signals are very "straight-arrow" and must have an unblocked line of sight to the shore based system. Things like trees, aluminum masts, light poles, etc. can all negate or hamper getting a good "lock-on". Boat masts are particulary vexing as they tend to move - swaying back and forth or rotating into or out of the line of sight path between your system and the shore system. Here is where antenna elevation can make a serious difference. Getting your antenna up high like mast top or whatever, can get you a clear line of sight whereas an antenna down low has more obstacles in its way.

- - Getting your antenna up high introduces more problems of cables and power losses due to cable length. (Nothing is ever easy). USB active extension cables can give you up to about 80 feet (25 meters) of extension. But that introduces the problem of getting power to the "active" part of the cable. Since computer USB ports are limited to about 500 mw is not uncommon for the computer to cycle the power on and off when the powered antenna wants too much.

- - So systems like Ubiquiti and others use outdoor rated ethernet cable to connect the masthead antenna system to your computer - and - use POE (power over ethernet) power supplies to keep the system running. The computer cannot put out enough power through the USB port to do the job. This solves a lot of problems and the systems work quite nicely.

- - Other systems use auxillary USB hubs powered from a separate power supply to get the "juice" to the antenna system. Data Alliance has a lot of Alfa system stuff and some rather long active USB extension cables. Antenna Cables: Use USB Cable as alternative (if possible) for More Gain

- - Bottom line, it is normally not so much which brand of WiFi antenna system you use, but the components in that system that make the difference - not to forget environmental obstacles to your line of sight requirements.

- - We have had very good performance from RadioLabs systems including their Captifi 1000mw bulb system - which we still use. But with most all things - computer - everyday or week something new and "better" comes along. So we are migrating to a permanently installed masthead system with supplemental power supply. Remember computer USB available power is just not enough for the big systems.

- - Standing back and looking at various cruising boats these days - more and more they are starting to look like NASA antenna farms. I remember when sailboat masts used to be used for hauling up just sails rather than also a farm of antennas.
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Old 05-12-2011, 06:51   #1067
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Re: Long-Distance WiFi Device

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Originally Posted by osirissail View Post

- - So systems like Ubiquiti and others use outdoor rated ethernet cable to connect the masthead antenna system to your computer - and - use POE (power over ethernet) power supplies to keep the system running. The computer cannot put out enough power through the USB port to do the job. This solves a lot of problems and the systems work quite nicely.
Well, I can agree with that one point.

I think that if wifi is important to you, you will have a range of options. Sometimes, with all the firepower I have available to me, the alpha with a hi-gain omni hanging up in the cockpit is the only thing that works. This seems contrary to all the engineering "facts" on the topic and yet... there it is.

George

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Old 05-12-2011, 06:54   #1068
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Re: Long-Distance WiFi Device

Actually, the receive sensitivity is the most important quality for good connections - not the transmitting power. Transmitting power is almost inconsequential after a point. Those big antenna on AP's also receive as well as transmit. Getting a good signal reception on the boat end is the whole game. The "return" signal from the boat back to the access point is rarely the limiting factor.

While you are correct that a clear line of sight is preferable, masts and trees don't block radio signals very much. Instead, they disrupt the signal polarization and create multi-path propogation - which is the real problem.

And these systems have been out for many years - not just in the past year. Any place you have used an access point over the past 6-7 years, you have used these systems. However, it seems that they have just been "discovered" by cruisers in the past couple of years.

In choosing a system, there is really only three fundamentals to keep in mind:

1. Coax kills. If the system has more than a 6" pigtail of coax connecting the radio to the antenna, run away.

2. If you want the radio/antenna more than 15' away from your computer, get either an ethernet-based system or a wireless access point system.

2a. If you think you can use externally powered long active USB cables to mount a USB client a long way away from your computer, you will be disappointed in practice.

3. Actual transmitting power is inconsequential after a point. If your total signal output (radio output multiplied by antenna gain) is greater than 500mW, you won't gain much more by going higher. Luckily, you don't really need to think about this last point because all systems being sold now are higher than this.

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Old 05-12-2011, 06:56   #1069
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Re: Long-Distance WiFi Device

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Originally Posted by thatboatguy View Post
Well, I can agree with that one point.

I think that if wifi is important to you, you will have a range of options. Sometimes, with all the firepower I have available to me, the alpha with a hi-gain omni hanging up in the cockpit is the only thing that works. This seems contrary to all the engineering "facts" on the topic and yet... there it is.

George

George
That isn't contrary to any engineering "facts" at all. That is a valid and widely used type of wifi system.

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Old 05-12-2011, 09:39   #1070
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The most difficult problem to deal with is what is called the "hidden node" problem. Google it for specifics, but it basically means that your wifi must not just be able to communicate with the AP but also receive every other client that is using the same AP. The longer distance people try to work, the tougher this gets.

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Old 06-12-2011, 08:33   #1071
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Re: Long-Distance WiFi Device

Coming to you *live* over fifty feet of USB extension cable! heh heh

I hope that next week I'll have time to complete the totally wireless Alfa option. And I mean no wires at all, hoist the thing as high as you like.

George
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Old 06-12-2011, 08:55   #1072
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Quote:
Originally Posted by thatboatguy
Coming to you *live* over fifty feet of USB extension cable! heh heh

I hope that next week I'll have time to complete the totally wireless Alfa option. And I mean no wires at all, hoist the thing as high as you like.

George
Are you eluding to a wireless repeater type setup?

All fhe tech talk is interesting but I am lurking here in the hopes to pick up some concrete equipment recommendations.

I want to anchor near some wifi, have a unit on my boat that picks up the wireless signal at "long" ranges and then repeat that signal as my own boat based, shared local wireless network. Ipads and iphones dont have usb or ethernet ports.

I gotta believe this technology exists but I don't know what to buy.
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Old 06-12-2011, 09:02   #1073
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Re: Long-Distance WiFi Device

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Are you eluding to a wireless repeater type setup?

All fhe tech talk is interesting but I am lurking here in the hopes to pick up some concrete equipment recommendations.

I want to anchor near some wifi, have a unit on my boat that picks up the wireless signal at "long" ranges and then repeat that signal as my own boat based, shared local wireless network. Ipads and iphones dont have usb or ethernet ports.

I gotta believe this technology exists but I don't know what to buy.
Yes, I'm building an Alfa based repeater type setup which I intend to document openly. Not looking to break anyone's rice bowl but this is just how I roll.

In the meantime, I can highly recommend to you the Island Time setup that I and many others have recommended here. It's a great set of hardware that comes with great tech support. Don't hold your breath on me actually doing *anything* in a timely manner. I am in cruising mode and might find more interesting stuff to do in Freeport next week than I expected. After that we will be in the boonies with no wifi (I think) for a week or more before we get into the Exumas.

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Old 06-12-2011, 09:06   #1074
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Quote:
Originally Posted by thatboatguy

Yes, I'm building an Alfa based repeater type setup which I intend to document openly. Not looking to break anyone's rice bowl but this is just how I roll.

In the meantime, I can highly recommend to you the Island Time setup that I and many others have recommended here. It's a great set of hardware that comes with great tech support. Don't hold your breath on me actually doing *anything* in a timely manner. I am in cruising mode and might find more interesting stuff to do in Freeport next week than I expected. After that we will be in the boonies with no wifi (I think) for a week or more before we get into the Exumas.

George
Cool! I wont hold my breath :-)
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Old 06-12-2011, 11:43   #1075
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Re: Long-Distance WiFi Device

Hi All,
Thanks for all the great info posted on this thread.
My wifi setup has been working for 4 years now. It is in Revision 2 with the introduction of the Nanostation M2. Here is a video of it in motion.

https://picasaweb.google.com/1032711...80744861715842

It provides onboard hotspot and a directional link using Ubiquiti products.
The key for me was to keep the Nanostation pointed at the Access Point. The rotator has a digital compass inside that is used to keep the servo pointing at the same place regardless of how the boat swings.

I currently use Bluetooth to talk to the controller and set the heading.
The only wire going to it is power (+12v,Gnd) Nothing else.

Version 3 will have slip rings so it will have unlimited rotation capability.
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Old 06-12-2011, 12:23   #1076
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Re: Long-Distance WiFi Device

The Alfa R36 router/repeater can take a signal from a simple USB adapter like the AWUS036H and repeat it as a wifi hotspot in your boat. Cool little device.

It only repeats wifi B&G signals, not N yet. They say they have an engineer or two working on that. . . .
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Old 06-12-2011, 14:00   #1077
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The Alfa R36 router/repeater can take a signal from a simple USB adapter like the AWUS036H and repeat it as a wifi hotspot in your boat. Cool little device.

It only repeats wifi B&G signals, not N yet. They say they have an engineer or two working on that. . . .
Oh no... Pls. stop, that's about the worst setup. Repeaters kill the bandwidth that needs to be shared by all.

It's in this thread a zillion times: if you need to ask, go to Island Time PC or wififorboats.com and get the kit.

cheers,
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Old 06-12-2011, 14:07   #1078
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Re: Long-Distance WiFi Device

Sorry -- I should've prefaced my post with "Advice from a Wifi Dummy." As Ex-Calif said, all the tech talk is interesting but. . . . A lot of what gets tossed around here is Greek to the average guy. The R36 is simple, cheap, and it works like a miracle for me. I look forward to seeing what the proper equipment can do.
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Old 06-12-2011, 14:37   #1079
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Sorry -- I should've prefaced my post with "Advice from a Wifi Dummy." As Ex-Calif said, all the tech talk is interesting but. . . . A lot of what gets tossed around here is Greek to the average guy. The R36 is simple, cheap, and it works like a miracle for me. I look forward to seeing what the proper equipment can do.
Yep, that is why I say to buy the kit. It's complete and comes with instructions and support. Not being an expert is no valid reason to use bad systems or setups. You just buy the right kit and be happy. Performance will be incomparable to toys like repeaters and usb-sticks.

cheers,
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Old 06-12-2011, 16:25   #1080
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Re: Long-Distance WiFi Device

Nick, a repeater isn't necessarily a bad thing. If it is designed to be hoist up your own mast, for your own boat, if could be suitably low power so that someone 100 yards away wasn't bothered by it. Sizing the bubble...maybe automatically stepping the power just to match the user connection? Could make it a good neighbor.

Or, stepping it up to max power and letting all the nieghbors share on it.<G>
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