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Jon Hacking · 26-07-2011, 08:18

Quote:

Originally Posted by David_Old_Jersey

... can anyone give me a rough idea of how far it is possible nowadays to get WIFI access with basic (and cheapish!) technology? ... 100 yards / 5 miles?

One problem with long distance WiFi is that it implies that you're pirating someone's signal. That's probably OK in the US where bandwidth is free, but it's not nice if someone else has to pay for the bandwidth you're using. I'd rather go with a 3G modem (I think this is what folks have been calling Net-Sticks). The modem itself is about the size of your finger with a USB jack on one end. They cost about $40 these days, & data plans are usually under $1/day. You have to buy it a SIM in each new country (like your phone) which is usually easy (except in Europe?) We get a usable signal up to 18nm from a cell tower. Basically, if you've got cell-phone signal, you've got internet. Speeds here in Malaysia are typically 50KB/sec - not blazing but very usable, & almost all of the coast has coverage. Thailand has good coverage but speeds are slower (& cheaper).

SatPhones can certainly be used for offshore internet access but they're dog slow (2400 baud at best, no matter what they advertise) expensive to buy (~$1200 for an iridium handset) & even more expensive to use ($700/yr for 500 minutes). Iridium is worldwide because their satellites can talk to each other, so your signal gets relayed through several satellites before coming down to a ground station. With GlobalStar, the satellite you are talking to must itself be able to see a ground station, so they don't work very far offshore -Maybe 200nm.

We've used Winlink (Ham radio) for email for 10 years & we love it (see our Radio Email page for costs, etc). We limit attachments to 50KB but it works anywhere in the world (OK, coverage gets a bit thin towards the bottom of South America). We can't surf the web but if we know the exact URL we can request it be sent to us (a service we never use). We get GRIB weather charts sent to us whenever we're on passage.

Winlink is free for licensed Hams & the test is much easier now that they've removed the code requirements, but if you don't want to take the test you can use SailMail for $300/yr, which provides a similar service but on the Marine SSB bands.

zeehag · 26-07-2011, 08:33

there is no wifi at sea. there is sailmail via ssb. there is iridium there is sat ---and all at a big price. surfing the web at sea??? LOL..i dont think so unless you are willing to pay thru nose. there isnt time at sea to play internetz----

in port there is wifi, with a half mile range. YOU add the boost. sometimes the free wifi actually works.

dial up broadband and use of smart fone as a modem need cell towers in range-- preferably within sight. not all cell towers will give you a signal--depends on the ownership and all that. sprint doesnt work with at&t towers.. go figger.
have fun and smooth sailing.

**FrankZ** · 26-07-2011, 08:48

Quote:

Originally Posted by virginia boy

I got tired of weak, or inaccessible wifi connections (anchored in Potomac River wash dc) and decided to pay the extra 20 dollars to tether my iphone. I get 4 gigs for that $20 and for each additional gig after that it's $10 more. Virginia Girl can now work from the boat instead of spending the day at the library or starbucks. My bill for the past month was $180 USD. Worth every penny.

Get the same plan but change to an Atrix and get 4G speeds as well.

I recently got one and it has mobile hot spot capability. It needs to be plugged in (or you won't get but an hour or two of use) but you "tether" with WiFi.

svcambria · 26-07-2011, 09:19

Quote:

Originally Posted by David_Old_Jersey

Without getting all technical

..........can anyone give me a rough idea of how far it is possible nowadays to get WIFI access with basic (and cheapish!) technology? (I don't want an antenna array that can double as part of SETI

).

100 yards / 5 miles? (all things being equal, blah blah

).

Without getting too technical...

With a home-assembled system like the Rogue Wave (antenna, bullet ethernet converter, amplifier, ethernet cable) I can transmit for a couple of miles. Receiving depends on the station I am communicating with.
I see the Rogue Wave people are very coy about their prices, but with a little legwork I got my system working for about $170 US. I got a lot of useful information from here:
http://www.cruisersforum.com/forums/...rks-36478.html

You get to struggle with what kind of antenna, but most of them are pretty small. Mine is "directional" (works pointing in one direction with about a 60 degree aperture) and is about a 20 cm square, 3 cm thick, clamps onto a stanchion.

Michael

Jon Hacking · 26-07-2011, 19:37

Quote:

Originally Posted by svcambria

...You get to struggle with what kind of antenna, but most of them are pretty small. Mine is "directional" (works pointing in one direction with about a 60 degree aperture) and is about a 20 cm square, 3 cm thick, clamps onto a stanchion. Michael

Directional antennas, of course, don't work well when you're swinging around at anchor. There's always a trade off here. Your antenna will only transmit the power you feed it - the trick is making that power go in the direction you want. A flat "patch" antenna like Michael's will direct your energy into a cone but you'll probably still find yourself adjusting it often unless you're tied to a dock. The angle of that cone depends mostly on the size of the antenna, so you should read the specs. A larger, higher gain flat antenna will transmit further but will have a narrower cone, so will need more adjustment.

A vertical antenna will radiate in all directions. I'm going to use a VHF antenna analogy here, but it's the same for WiFi. The shorter, low-gain antennas will radiate a fair amount of power up & down as well as horizontally. That's why sail-boats have to use short 3dB whip antennas for our VHF radios, while power boats (& also multihulls, that don't heel) can use longer VHF antennas with higher gain. Monohulls need their VHF radios to work even when they're heeled over, so they have to use low-gain VHF antennas. If you think of the radiation pattern as a donut (with the antenna sticking up through the hole) then the higher gain antennas flatten that donut, squashing it down so it doesn't radiate as much up & down but goes further out to the sides. This is probably a better type antenna for WiFi - a high-gain vertical that radiates in a thin horizontal plate & doesn't waste power up & down. Put it as high up as practical to get over obstructions. It won't work well while you're sailing, but that's probably OK.

BTW, antenna gain affects both transmit & receive. A high-gain antenna will improve both the same amount. But getting a high power transmitter won't help you receive any better (& you need to do both) so that's probably of limited usefulness unless you're talking to another high-power transmitter.

Also, at WiFi frequencies (1-5GHz) you will lose most of your power, transmit & receive, in your co-ax cabling if you're not very careful. You either need very short co-ax runs, or very large cable like RG8 or RG213. The best configuration is to put your WiFi transceiver right at the antenna, even if that's up the mast. Then run a long USB cable to it, because USB is digital & won't suffer any signal loss (if you use a good quality cable). Of course, this means that everything must be waterproof.

David, I hope that's not too technical...

Yofy · 27-07-2011, 03:33

Great detailed explanations Jon.

And FYI SIM's are available all over the Med these days including Turkey, Greece, Israel, etc....
Manny

svcambria · 27-07-2011, 11:50

Quote:

Also, at WiFi frequencies (1-5GHz) you will lose most of your power, transmit & receive, in your co-ax cabling if you're not very careful. You either need very short co-ax runs, or very large cable like RG8 or RG213. The best configuration is to put your WiFi transceiver right at the antenna, even if that's up the mast. Then run a long USB cable to it, because USB is digital & won't suffer any signal loss (if you use a good quality cable). Of course, this means that everything must be waterproof.

Or perhaps even better - a long ethernet cable which is not restricted by length... (I thought there were timing issues using USB which couldn't be overcome after so much distance which is also "so much time" travelling through the wire.)

Yes, the directional antenna certainly has some drawbacks at anchor - which promotes short sessions "on-line" - which is a good thing...

Michael

sabray · 27-07-2011, 12:20

Ethernet cable is only good for about 365 feet. You will need a fiber cable. Ruckus wireless did something ally smart. Because they are limited in broadcast strength their ap antenna is actually 8 separate units the ap senses the client and puts all the owere where it is being used. What we need is a smart uni directional antenna.