satellite communications

[captjohn360]

direct tv and dish offer tv plus internet.can i get a mobile satelite receiver and cruise and still receive service? if not why not.and is there anny one doing it....jt

[Pblais]

Depends on where you cruise. You can check out the coverage area for TV. Internet is another matter.

For Internet, I had it here in VA for a year at our house not on the boat. The the equipment was $2000. The download was good at 1 mb but the upload was far far less. Mostly about the same as a good dial up modem connection. WE had terrible phone service here too. From anything other than a rigid platform the antenna will never work. Even the "mobile" systems need a stable platform to mount them on and the satellites are lower in the sky than the TV. That makes it harder to lock. The fact that you transmit on it too makes it even harder. I have seen the Internet dish mounted to a pylon in a marina. The TV dishes are small and more portable and far far easier to calibrate. There are lots of different TV systems that can work well aboard even under way if you have the power to run them.

The Internet dishes are wider and use far more power than the TV dishes. For the Internet service I used DirecWay at a low commercial level since I used it for business and it was $129 / month. TV is the same price you can get a price off the web and they do not share the same dish or equipment at all.

The really high level commercial service uses a larger fixed dish and works great and costs a lot. You see them mounted on top of convenience stores and are used to report sales information.

You'll only be able to run the Internet service at a marina and then you'll need a southern view to the horizon. The dish has to be mounted on something attached to land. The mobile version for vehicles is not that great and is very expensive and you need to be parked.

For communication and data at sea you need to think "US Navy". They own their own satellites and don't share them with anyone. There really is nothing available nor likely to be available from satellite coverage that is affordable. Sat phone service isn't going to get cheaper. Splitting the bandwidth is about as good as it gets now. The phones are rugged and relatively cheap, but the service is not. Buying large 1000 - 5000 minute bundles can save some money.

For global Internet service there is nothing really out there except sat phone and SSB radio. The SSB coverage is limited to plain text and weather and is affordable. The sat phone is easy to use and you pay by the minute and is not cheap at all. For really cheap you can get a USB drive loaded with a U3 launcher and just attach it to a land computer at a local Internet cafe. You can find them in more far away places than you might think.

[Harriet]

We just put our DirecTV dish and receiver in storage, as we are heading for the Caribbean. We tried to use it in the southern Bahamas last winter, and we basically got 3 channels (how many reruns of CSI can you watch?). The farther south you go, the less reception you get. Although we could perhaps get a new receiver in the Caribbean, most the of channels will broadcast in French or Spanish. For the space and weight vs. utility, we decided to leave it ashore. And Paul is absolutely correct about the internet dish - it is much too big for the average cruising boat.

[Radio University]

From what I just read from the DirecTV website, it looks like the High Speed Internet is a DSL telephone line and NOT through the dish and satellite like DirectWay. They are saying that they "partnered" with someone to provide internet access. I am guessing that it is the same with DishNetwork. Just a DSL bundled package. Not internet through satellite...

If you are looking for text based email, the SSB and a pactor modem, Globalstar phone or Skatmate are really the only affordable options.

[captjohn360]

hey thanks direct tv offers tv and internet via satellite some friends in n.c. use it they dont have a land line. direct also has direct satellite llc in the carribbean so i thought it would work....jt

[FrankZ]

Another problem with sat internet connections is latency. One packet has to travel about 48,000 miles and the acknowledgement does the same. There are certian applications that are just not friendly to that. Downloading a file is ok, once you get it moving. Streaming might not be as happy. Any sort of terminal application is horrible.

[Pblais]

Another problem with sat Internet connections is latency. One packet has to travel about 48,000 miles and the acknowledgment does the same.

The latency isn't so much the distance traveled but the queue you wait in to use the satellite for data coming from the Internet to you. The stuff is going speed of light. No difference than emailing from my house to OZ.

The transmission starts with you and goes up then down to Ohio but when the response comes back they can only send one data stream to the satellite from the Network Operations Center in Ohio but it is a very high bandwidth signal using a really big dish with lots of power. What they do is your request for a file or web page to be sent to you gets split into many requests so they can in effect gather them quicker then send you bigger packages. Your package has to wait in line to be transmitted and that is where the latency comes in. I used it for a year and it's normally not that bad for web surfing. What is bad is the uploads from you to say an FTP site because the ACK that comes back to you when you send data has a longer latency than normal and it artificially makes the speed you can transmit a file lower than it really is because your target on the other side can't send the ACK's as fast as you could receive them. Your system has to wait for the ACK after each packet is send and with the latency delay it makes it seem dog slow. The bottom line is downloads are OK but uploads tend to suck.

The original Hughes satellite system used a telephone for the upstream side and the dish for download. DirecWay does it both ways. The really nice stuff called SpaceWay is higher bandwidth up and down but it's not cheap, and uses a bigger dish than even DirecWay. It's really meant for large companies out in the boonies.

[FrankZ]

Part of the latency is directly related to the distance. Light is fast but it only goes so fast and with the distances that occur the times add up. Most sat connections see latency of more than 700ms which is huge in networking. Couple that with any manipulations that happen at the provider and it adds up even more. I was in SC recently to help an exec with his connection. He uses directway and I was seeing ping times of more than 1 second. Couple that with anything that is packet intensive (Citrix in this case) and it makes for a very poor user experience.

Anther applications that would be of interest is VOIP. VOIP tends to use lots of small packets which doesn't lend itself to efficent packet shaping. That coupled with timeouts that can occur causing TCP retransmits helps to compund the issues.

Another issue is sat connections tend to be asymetric with the upload speeds very low compared to the download speeds. This can cause issues if you try to do more than one thing at a time. Browsing websites while waiting for a file to download can saturate the upload channel as it sometimes isn't large enough to handle the number of ACKs. This happens on some cheaper broadband connections as well where you see 1.5M/96K speeds.

[Pblais]

This happens on some cheaper broadband connections as well where you see 1.5M/96K speeds.

That is what DirecWay seems to be nominally. The upload can actually be less at times. I would agree a Citrix session would be bad news. Downloads and surfing worked quite well though.

[captjohn360]

thanks guiesfor the info i guess you are saying it will work just slow....jt

[thefantasea]

So, do I understand that there is really no reasonable alternative to SSB for internet access while at sea, and the acceptance of the stringent limitations involved?

[SilentOption]

Sorry to butt in

How are the guys who race around the world getting weather and email?

If I am planning to sail primarily from Virginia north as far as Canada out to Bermuda and no farther south than St Croix, St T area what are my options for weather and email?

Thanks

[Radio University]

SkyMate is a great alternative. Take a look...

SkyMate | Wherever you go. Whatever you need.

[yotphix]

Interesting program! Do I understand correctly that this system is somehow using vhf to transmit data? How is this possible offshore? The "how it works page isn't up yet!"

[Radio University]

SkyMate uses the ORBCOMM low-earth satellite system which is about 32 satellites...

This is how they get away with using a 38" vertical VHF antenna tuned for the SkyMate system.