Who is the Most Sailor-Friendly Iridium Service Provider?

[svseachange]

Originally Posted by goboatingnow

Can you elucidate the reasons for your prepaid over bill pay decision, as you see it , I'm a bill pay iridium and could never see the economy of pre pay , my annual usage bill is under that $800 cost

Dave

Sure.

The Monthly 30 contract costs $60/month or $720 year. The 30 minutes expire at the end of each month unless you pay an extra $5/month, bringing the total cost for 360 minutes for 12 months to $770/year. Plus tax and shipping this is more than $800. The same $800 gets 500 prepaid minutes (inc tax and shipping).

The fine print of the satphonestore contract says you must pay the cost of the contract for the remainder of the year if you cancel early. For satphonestore the monthly contract seems to make no sense unless you are short on money upfront.

[svseachange]

Originally Posted by Paul Elliott

These features and optimizations make a huge difference in the usability of satphone digital services. It's not snake-oil.

Thanks, I was wondering about the snake oil factor.

I'm interested to see how downloading the data via zyGrib works before paying for a compression service. Will report back.

Regarding getting emailed grib files from saildocs, getting the data from saildocs via email feels like adding unnecessary packaging. Why does it make sense to get the data packaged as an attachment to an email when you can use zyGrib to download the data directly via ftp?

[Paul Elliott]

Originally Posted by shanedennis

Thanks, I was wondering about the snake oil factor.

I'm interested to see how downloading the data via zyGrib works before paying for a compression service. Will report back.

Regarding getting emailed grib files from saildocs, getting the data from saildocs via email feels like adding unnecessary packaging. Why does it make sense to get the data packaged as an attachment to an email when you can use zyGrib to download the data directly via ftp?

I should look into the zyGrib FTP method. As long as the FTP is running on top of a satphone-optimized lower layer protocol it should work well. As for email, the basic email overhead in byte count is pretty minimal when compared to even a small GRIB.

When evaluating satphone digital protocols, we need to look at not just compression efficiencies, but also handshake overhead and turn-around times. If the protocol is not optimized the long latencies of satphone connections these can really add up and substantially increase the connection time. Since we pay for satphone connect-time this can make a significant difference in cost.

ZyGrib / FTP may be doing all of this very well -- I don't know.

[Edit:] I just looked at the zyGrib website. It just uses standard FTP, so the optimization will need to be done via a satphone gateway proxy or something. Does anyone have any details about how this might work? It's all a bit over my head.

[Palarran]

Originally Posted by shanedennis

Regarding getting emailed grib files from saildocs, getting the data from saildocs via email feels like adding unnecessary packaging. Why does it make sense to get the data packaged as an attachment to an email when you can use zyGrib to download the data directly via ftp?

I agree. This advise is always posted and I can't figure out why except that some guys are living in the past or haven't used the 9555. It takes 5 minutes to download a grip - how much more can you save using saildocs, 1 minute? Whooptidoo here's your dollar $

I used ugrib but zygrib appears to be exactly the same.

[svseachange]

I probably need to do a test. I assume the services use a server to compress data before sending and then decompress it using some kind of client software on the end users machine.

For old timers, compression kind of works like shorthand. Since grib files are already written in another type of shorthand I wonder how much is gained in compression.

A simple test would be to zip a crib file and see how small it becomes. This should provide an approximation of the time (and money) savings to be gained by using a compression service for ftp.

Will report back.

[svseachange]

Did the test, and now I remember doing it a few months back. I am getting old...

The zyGrib server compresses the files using bzip2 before sending it to the zyGrib client. zyGrib then decompresses the file before loading it. The "tech"s know already, the bzip2 files are already tightly compressed.

In effect, this means zyGrib acts just like a compression service. For this reason I doubt a compression service would make a lick of difference. I suspect using the compression service would simply add overhead making a zyGrib download slower. Using saildocs email grib service does not seem to make any sense if you are using zyGrib.

[Paul Elliott]

Originally Posted by shanedennis

Did the test, and now I remember doing it a few months back. I am getting old...

The zyGrib server compresses the files using bzip2 before sending it to the zyGrib client. zyGrib then decompresses the file before loading it. The "tech"s know already, the bzip2 files are already tightly compressed.

In effect, this means zyGrib acts just like a compression service. For this reason I doubt a compression service would make a lick of difference. I suspect using the compression service would simply add overhead making a zyGrib download slower. Using saildocs email grib service does not seem to make any sense if you are using zyGrib.

What are you using for the Iridium data service connection? Is it Iridium's "Direct Internet 3"? Has anybody done a comparison of this to XGate or other accelerator services? I have to admit that I haven't tried the "native" Iridium data services since my initial experience with their completely unusable offering about ten years ago, after which I signed up with XGate.

I have now installed Direct Internet 3 and will try it out. I don't know if I will have to work on my firewall settings. Also, if I use this for email (instead of XGate) I will need an email service with file-size limiting, etc. Getting an email with a huge attachment can otherwise effectively kill your Iridium service.

zyGrib looks good, but there are some Saildocs features that zyGrib doesn't seem to have:

With Saildocs I can set up a subscription where a file, or set of files are automatically mailed to me at a specific time or times every day. I can also specify non-uniform GRIB intervals: for example, I often get the present conditions, then the forecasts at 6 and 12 hours, then 24, 48, 72, and 96 hours (I figure that fine-grain forecasts are pretty useless after a few days, but the general trends might be accurate enough for rough planning). These aren't show-stopping features, but I like having them. With Saildocs I can (and do) also get the synoptic WFAX charts.

[svseachange]

Originally Posted by Paul Elliott

What are you using for the Iridium data service connection? Is it Iridium's "Direct Internet 3"?
.......
With Saildocs I can set up a subscription where a file, or set of files are automatically mailed to me at a specific time or times every day. I can also specify non-uniform GRIB intervals: for example, I often get the present conditions, then the forecasts at 6 and 12 hours, then 24, 48, 72, and 96 hours (I figure that fine-grain forecasts are pretty useless after a few days, but the general trends might be accurate enough for rough planning). These aren't show-stopping features, but I like having them. With Saildocs I can (and do) also get the synoptic WFAX charts.

I set up the phone as a generic 19200 baud modem and dial 008816000025. With no external antenna, just the phone sitting on my chart table, download of a 50Kb compressed grib from Zygrib takes about four minutes. Sometimes the connection to the Zygrib server is not maintained because of the slow/unreliable connection and I have to start the download again (expensive).

I am new to this and did not know about Direct Internet 3.0. I installed it after seeing your post. Time taken to download the file is the same as using the generic 19200 baud modem method. I suspect this is because the Zygrib server already compresses the file before sending. However I am betting the Direct Internet 3.0 connection is more stable and I hope it will keep the connection with the Zygrib server if the connection drops momentarily and this reduce the need to restart downloads (ie: save money).

I mostly agree with your analysis of Zygrib - no emails, no WFAX. In terms of gribs I think the services are about equivalent. I've been looking for sources for WFAX, but it is hard to get around the fact that these are image files and are going to be big (ie: very expensive via Iridium).

[LakeSuperior]

We used XGATE and Saildocs extensively. XGATE will not try to resend the whole GRIB file if the connection is dropped. It will seamlessly pickup where it left off on the reconnect.

The bottom line is that the GRIBs will provide you with all the "actionable" weather information you will need.

I will say that an external installation (at the chart table nerve center) with handset and external antenna is more or less a requirement. Plus the external antenna seems to have more gain which makes for faster data transfer so I was told.

[Paul Elliott]

Here is more info on getting WFAX charts via Saildocs. As you will see, the filesize is about one-half of the normal NOAA WFAX chart (16kBYtes vs 32 kBytes). This is larger than your typical small GRIB, but not ludicrously so.

Note that Saildocs only has the ".TIF" format images. If you request the .GIF version it comes up "not found".

-----------

WFAX via Saildocs
If you get the wfax files through Saildocs, the filesize is compressed by about 50% from the original NOAA files. The resolution isn't quite as good, but they are still very usable -- and probably still look better than if you had received them off the air.

Here is the NOAA catalog: Index of /pub/fax

This is their list of files for the Atlantic: http://weather.noaa....fax/rfaxatl.txt
Pacific: http://weather.noaa.gov/pub/fax/rfaxpac.txt


Once you figure out which files you want, you can get them through Saildocs.

If I want to see the PYBA01.TIF (Pacific Surface Analysis), I send email to:

[to:] query@saildocs.com
[subject:] doesn't matter
[message body:] send PYBA01.TIF

The file I get is about 16 kBytes, while the NOAA version is about 32 kBytes. Note that I am not requesting the file with the full path to the NOAA ftp site, but just the filename. I assume that Saildocs is keeping a local cache of these files in compressed format, or perhaps they do the compression on the fly. It's definitely not the same file as I get directly from the NOAA server. Instead of "send" you can also use the subscribe method.

http://weather.noaa.gov/pub/fax/robots.txt
ftp://tgftp.nws.noaa.gov/fax/Amaster_index.html

[svseachange]

Originally Posted by LakeSuperior

We used XGATE and Saildocs extensively. XGATE will not try to resend the whole GRIB file if the connection is dropped. It will seamlessly pickup where it left off on the reconnect.

The bottom line is that the GRIBs will provide you with all the "actionable" weather information you will need.

I will say that an external installation (at the chart table nerve center) with handset and external antenna is more or less a requirement. Plus the external antenna seems to have more gain which makes for faster data transfer so I was told.

Thanks. So far Direct Internet 3.0 looks good. If it does not work out I will take another look at XGATE.

We have an external antenna but I get such good reception I have not been bothering with it. Sounds like I need to break it out. I'm really impressed by reception of the sat phone, and after listening to the stories of people with non-Iridium phones glad we paid the premium for Iridium.

Sent from my GT-P3113 using Tapatalk

[svseachange]

Thanks Paul. That is great information. I will be referring back to your post.

Sent from my GT-P3113 using Tapatalk

[Navigation Mac]

Last release of tutorial iBook " Get Weather Forecast with Satphone at Sea" available on iBook Store. Updated satphone and airtime pricing and added new IsatPhone2 description.