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Old 21-05-2008, 12:29   #1
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e-mail via Iridium Phone, w/o X-Gate

I've done a cost analysis of X-Gate and the upshot is if you're using e-mail a lot and out cruising for months at a time, then X-Gate is a very good idea.

But for my particular situation, it's not. I'm going to be sending e-mail once a day at most. I'll be doing this for 18 days. In fact, the mail I have to send every day (position update, course and speed) I can do over the Iridium phone with free SMS messaging. So it just doesn't make sense to spend $140-something bucks to send e-mail every other day or every third day for 18 days.

HOWEVER....I hear that *without* X-Gate, at least a few years ago, e-mail transmimssion was very, very iffy, and truly almost impossible to do over an Iridium telephone. So my questions is, Who here has actual Real Time experience sending and receiving e-mail over an iridium phone without X-Gate or any other fancy compression? What's the deal?

MORE INFORMATION:

I'm a geek. I do tech support for a living. I am setting up a POP/SMTP mail server on a spare machine at work. It will be the Mercury POPmail server running on Windows 2003 server and I will use Pegasus as my POP client on ly laptop. I am renting the Iridium 9505a and also the serial/USB data interface.

There are no fancy graphical doo-dads, here on the mail server. No nifty little yahoo or hotmail graphics get sent with this mail. It's handshake-text transfer and that's it. Nobody will have this address but my wife, a backup person and the Race Committee. Oh, and I'll request saildocs GRIB files 2-3 times, so Saildocs will have it.

i am setting up auto-forwarding on the server so that when I want to send e-mail updates to a mess of people, the server handles it, not my mail client. I don't have to send mail 3x to get it to three people, or even handshake 3x with the server for the 3 cc's, the server just auto-forwards the mail to the addresses I specify.

OK with all that information in place....WHAT SAY?
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Old 28-11-2008, 05:53   #2
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Hi Alan
i was wondering about the same thing. I am ordering a phone and see that is you use there "Direct internet data" server they claim you can get 10kbs as opposed to 2.4. Aparently the server uses is own compression software too. Do you know anything about this or have you found out anything since your april post?

BTW mailasails service looks very similar to x-gate and around half the price
thanks,
Rijk
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Old 28-11-2008, 10:48   #3
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I used Iridum and their skyfile email service during my crossing from San Fran tom Hi two years ago. We had no problems at all. I sent it to multiple address's. Still have the phone and service It is useful in some anchorages where there is no cell coverage. I had a weather guy sending weather every other dax with weather charts yes it is slow. I was not using it to surf the web, just like you letting everyone know where we were.

Mike
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Old 28-11-2008, 12:35   #4
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iridium

Quote:
Originally Posted by Alan H View Post

HOWEVER....I hear that *without* X-Gate, at least a few years ago, e-mail transmimssion was very, very iffy, and truly almost impossible to do over an Iridium telephone. So my questions is, Who here has actual Real Time experience sending and receiving e-mail over an iridium phone without X-Gate or any other fancy compression? What's the deal?
Mine seems to work just fine. I use mozilla thinderbird for email and saildocs for grib. Haven't used it offshore yet, just a couple of times in port to make sure it works.
PS Just timed (by counting) thunderbird using mobile phone connection and saildocs took about 20 secs to send request and download grib.
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Old 28-11-2008, 16:04   #5
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OK, so here's how it worked. I did the 2008 Singlehanded TransPac race from San Franacisco to Hawaii, last July. About every 3-4 days I sent pretty long updates via e-mail WITHOUT X-Gate to the race committee website. You can see the messages by reading here: 2008 SHTP - Log Reports

I'm "Ankle Biter"..

I used a very old Pentium II laptop with only MS WordPad (Not Word) as my text editor. I sent mail through a g-mail account, which I set up and only shared the account name with 2-3 people. NO SPAM. I didn't use X-Gate. It would take 4-5-6-7 minutes to send my mail and download the 4-5 messages I was getting, as well. I only tried downloading GRIB files once, and it was before I really got things figured out all that well, so I never completed that download.

Upshot is, for a short trip, just sending and receiving text, I wouldn't bother with X-Gate. But if you're out there for a year or more and you're sending and receiving a lot of attachments, that's a whole different story.
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Old 29-11-2008, 11:08   #6
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Geeky reply to why XGate is a good idea

There are several things you should know about iridium. Here are a few facts.
1. it takes about 20 secconds to bring up a ppp connection with iridium
2. the line turn around latency varies with the number of satellites in the link and can be as long as 3 seconds. This means that when you do ping over an iridium connection the ping could take 2-3 seconds. This is very important (see below). The closer you are to AZ and the fewer the satellites in the link the faster the line turn around.
3. Currently only one gateway is used for all civilian communication.
4. the nominal raw rate for iridium is 2400 baud which translates to about 18Kbytes per minute. It actually runs between 12 and 15Kbytes per minute for an average connection.
5. the iridium connection is duplex which means that you can send and receive concurrently over the link.

So what does this all mean for a user wanting to do e-mail over Iridium using standard internet tools.

1. Most e-mail clients do not support compression. This means that after you bloat your e-mail by converting it to mime format (mime increases a binary attachment size by as much as 40%) you transfer it over the link with 0 compression. On average text files compress by 50% which means that you could save 2x in your air time bill if you simply compressed the data before it is transmitted. If you compress multiple files into one block then your compression factors go up and your corresponding transmission costs go down. So... adding compression is a good idea.

2. Direct internet, provided for free by iridium, does compression. So... by adding direct internet to the equation you gain in performance.. However, there are something you should know about direct internet.
a. it only does run length encoding compression. Since it doesnt know the amount of data the compression cant be as efficient as that done by an application to application block compression scheme.
b. It doesnt work on vista
c. The dialup connection to the internet needs to be brought up manually. Once the connection is up it takes direct internet a while to negotiate with the compression server before the system is in place. This means that instead of looking at 20 second connection times, you must wait about 45 seconds before you start transmitting data. If you start transmitting data before the compression agent has finished initializing itself then the data connection runs without compression.
d. once you are finished with your session you must bring the connection down manually.

because of (c) there is no practical way to configure the auto dialers in e-mail clients such as outlook express to dial, send/receive, disconnect. when using Direct internet.

d. SSL mail connections (for both sending and receiving) cant be compressed. By definitiion encrypted data is randomized and cant be compressed. This means that if your e-mail service uses SSL you gain absolutely nothing by using Direct Internet. Actually... your performance is works since compressing a compressed stream results in a larger amount of data to be transfered.

e. Direct internet does no mid file restart, large attachment handling, header pruning, pipelining, or spam filtering. See below.

3. latency is a killer. As mentioned above 2-3 seconds for line turn arounds is typical over iridium. Looking at the SMTP protocol which is used by common mail clients such as thunderbird and outlook express you will note that 5 line turn arounds are required to setup the transfer and one line turn around is required for each email address. So... if you are sending an e-mail to 5 recepients then at works (5 + 5)*3 ==> 30 connections of air time are lost before you send a single characeter of your email over the link.

Receiving mail is also bad and latency is still a problem. After you do the pop authentication (which takes 5 line turn arounds) you have one line turn around for the directory listing and then one line turn around for the request of every file. Once the files are all downloaded then you have one line turn around for every file requesting the delete.

4. No mid file restart.

The killer here is that since the POP deletes come after all the files have been received, if you have a connection drop in the middle of your transmission you must start all over again! Sending mail is not as bad since the client gets an ACK from the server for every mail sent so you dont have to resend mails that have already been sent. If, however, you get a drop in the middle of an e-mail you are sending then you must resend that e-mail from the start.

5. no duplex operation.

Thunderbird and outlook express as well as most e-mail clients in the market run in simplex mode. They send mail first, then receive. This means that you dont have full use of all the available bandwidth. a 40% in time savings can be had if you were to send/reveive mail at the same time.

6. Standard e-mail clients/servers do not do header pruning. Take a look at a standard internet mail header. They can be huge. 5 Kbytes is not uncommon. Standard mail clients do nothing about reducing the size of the mail headers. Chopping the mail headers so that the contain the minimum amount of info (date, from, to, subject) can tremendously reduce the amount of data that is transfered over the link.

7. No intelligent attachment control... What would happen if someone were to send you a 1Mb picture as an attachment while you were out at sea? Your e-mail would be stuffed. Sure... you could configure you e-mail client to only list the headers of e-mail but this is a tremendously inefficient use of bandwidth and its expensive in air time.

8. No intelligent spam controll. Over 80% of all internet mail is spam. On average in a 24 hour period our service filters out 30 spam e-mails per active user on the system. Some users (i.e. me) can receive as much as several hundred spam e-mails in a 24 hour period if the system does not support intelligent spam control. There are many services that include this but you want to be certain that the system you use is friendly to satellite phones.

So... why is XGate (and other application to application compression systems) worth using? Because they address all of the deficiences mentioned amove.

XGate does the following.
1. It does block compression for maximum compressibility of the data trasnmitted.
2. it does mid file restart... after a disconnect XGate will start the transfer of data exactly where it left off.
3. I does protocol overhead removal removing all the dead time in standard internet clients by pipelining the ACKS. XGate has a total of 3 line turn arounds total for a connection independent of the number of files being sent/received.
4. duplex operation for maximum bandwidth utilization
5. intelligent and efficient large mail management
6. great spam controll offering several levels of server side customizable services.
7. convinient link control. With the push of a single button XGate will dial the connection, bring up the internet connection, send/receive, and disconnect.

So... if you are doing more than a single occassional text e-mail over iridium then XGate should be considered. XGate will save you considerable $$ in air time and reduce the frustration of doing e-mail over a slow expensive and contanquerous link.

XGate runs natively under windows, Mac OSX, and Debian Linux. All features are supported on all platforms.

One last thing... receiving SMS on iridium is free. up to 160 characters can be received for free on the phone. Sending SMS, however, is not free. it costs about $0.50 (varies with your plan) to send up to 160 character SMS from your phone. Using XGate to send e-mail is much more cost effective than using SMS for your messaging.

Take care.

--luis

Luis Soltero, Ph.D., MCS
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Old 29-11-2008, 22:34   #7
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I'm sure that everything that Luis Soltero says is correct. Absolutely, no argument.

However...

Iridium airtime costs $1.75 a minute. So if it take 5 minutes to send an e-mail to your friends, delivered to five address, that message cost you $8.75.

If you send three messages like that a week, that's $26.75. If you're doing a three week passage from California to Hawaii, you will spend $78.75 in airtime to send these nine messages to family and friends.

If you send an e-mail every other day, and you have a 4 week passage across the North Atlantic, then you will spend $122.50.

If you go Here: GMN-COMPRESSED SATELLITE EMAIL FOR IRIDIUM,GLOBALSTAR,R-BGAN, BGAN AND OTHER SATELLITE PHONES; ALSO WIRELESS E-MAIL FOR HF SSB PACTOR MODEMS

You will see that the shortest time you can get an X-Gate subscription is three months, and that it will cost you $139.

Spending that $139 will cut your airtime in half thus saving you roughly half of that $78.75, or half of the $122.50. Uh... do the math?

This is why I say that for short trips... one-time ocean races for a month or less, X-Gate doesn't make sense if you are just sending text-only e=mail. If you are getting text-only weather, the same thing goes.

If you are cruising for 3 months +, and sending 3-4 e-mails a day, including perhaps graphical weather files, that's a whole different story. Then absolutely X-Gate makes sense.
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Old 30-11-2008, 00:00   #8
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I've been using X-Gate, for about five years and have very happy with the service. However, when on passage I probably send a several email messages per day, and receive about 100KBytes of email - mostly gribs and compressed wfax via saildocs, so it probably makes more sense for me than for you (Alan).

But I really like the "resume dropped connection" feature of X-Gate. Before I had X-Gate it was really tedious to receive any large email (gribs, for example). A significant percentage of them would be interrupted and any partially-received data would be lost. This was with a good antenna, too.

Whatever you decide to use, I suggest that you test it to see how it behaves with a real-world Iridium connection.

Also, and I've argued this point with others, the Iridium system coverage nearer the equator is not quite as good as it is closer to the poles. Your dropped-call rate may be slightly worse as you sail towards the tropics. I've had good results at 10 deg South, and 20 deg North, but I think it's somewhat better near San Francisco. Perhaps the difference isn't enough to matter, but I think there is one.
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Old 30-11-2008, 15:57   #9
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When we had an Iridium phone I used mailasail compression software and was very pleased with the results and also the personal service we got from Ed Wildgoose who was excellent at helping us with any problems.

My business is 100% internet based and I used to send/recieve a minimum of 4-5 emails a day and I think it took about 2 minutes to do so. It isn't worth sending only one at a time as it does take time for Iridium to connect. Although expensive I reckoned each email cost less than a postage stamp (remember them?) We never used anywhere near our 500 minute quota in a year

I recommend contacting mailasail and seeing what they say. You'll find most of the ARC boats now use mailasail.

It has other features as well, like a great webdiary linked to google earth I also found the archive feature really useful. The standard mailasail email is stripped of all attachments, but you can go on line to download the attachment when you have a cheap internet connection.

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Old 26-10-2012, 06:17   #10
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Re: e-mail via Iridium Phone, w/o X-Gate

Luis, legend status confirmed! I think you did that without taking a breath too.
Cheers mate
mike
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Old 26-10-2012, 07:32   #11
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Re: e-mail via Iridium Phone, w/o X-Gate

Quote:
Originally Posted by Paul Elliott View Post
Also, and I've argued this point with others, the Iridium system coverage nearer the equator is not quite as good as it is closer to the poles. Your dropped-call rate may be slightly worse as you sail towards the tropics. I've had good results at 10 deg South, and 20 deg North, but I think it's somewhat better near San Francisco. Perhaps the difference isn't enough to matter, but I think there is one.
Iridium uses a network of 66 polar orbiting satellites. These satellites converge at the poles. So... as you move towards the poles the average satellite pass moves up in the sky ending up directly over head when at the poles. So... as you move north the amount of atmosphere interfering with your communication decreases, the probability of occlusions decreases and the number of satellites to switch to should there be an occlusion increases. As you move towards the equator the average pass is much lower on the horizon, satellite overlap is greatly decreased, satellites on average are further away from you, and there there is more atmosphere to contend to (remember that water absorbes microwave energy). So.. yes... iridium is at its worst at the equator and gets much better as you move n/s towards the poles.

Note that converse is true for Inmarsat that uses geostationary satellites. This is especially true for the isatphone. The further north you get the more difficult it is to use that hand held device.

Take care.

--luis
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Old 26-10-2012, 08:12   #12
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Re: e-mail via Iridium Phone, w/o X-Gate

Luis, that definitive! Paul knows why now, he's prob been wondering since 2008! well done and thanks.
Mike
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Old 26-10-2012, 10:30   #13
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Re: e-mail via Iridium Phone, w/o X-Gate

I'm glad this thread got revived -- it's a good one. I was pretty sure about the geometry of the polar orbits, but I hadn't considered the atmosphere effects. Don't get me wrong, Iridium works well near the equator, it just works even better closer to the poles.

Luis, during my Hawaii trip this summer I seemed to have more dropouts than in previous years. Have there been any changes in the satellite constellation? In early July we did have a solar storm that really hammered the system for a day, and perhaps the general solar levels being increased from the 2008 - 2010 sunspot minimum is having an adverse effect?
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