For me, Iridium did not drop calls with an external antenna.
1.2 megabytes is quite big. I used UUPlus for email compression
, which reports your link speed after every call, and I think with Iridium we tended to get around 20K/minute. So 1.2 megs would take an hour.
But I was able to get the weather I "needed" (I won't harp on this, but before I had this system I survived just fine at sea without daily GRIB files...), in less than 1 minute. You just have to request as little weather as you need-- so lower resolution, a smaller geographic area, fewer days into the future, fewer predictions for every day you request, less layers, and etc-- will make much smaller GRIB files. It took some experimentation, but eventually you have a little "request" sentence that you can cut and paste that gives you what you like without being a huge file.
We usually uploaded tiny baby pictures (more like thumbnails) to the grandparents while downloading GRIB files, since we would be connected for ~60s anyways and may as well use the upstream bandwidth for something fun.
You can use Sailmail's email autoresponders without subscribing to their service
. They are nice like that. You send an email to one of their computers
, which responds with the GRIB file you want.
People who subscribe to Sailmail can also use them to access email through their satellite phone
. This is much, much better and faster than using Outlook or whatever to get email through the satellite phone
, but does not have as many features as UUPlus, XGate, or etc.