IsatPhone Pro versus Iridium (continue)

As promised in my post on 15 July, here are the results of the comparative test conducted aboard "Prince d'Oc" for our trip from Port Leucate to Dubrovnik.

Thanks to the loan of a full IsatPhone Pro, with cradle and external antenna (big thanks to PYG @Voilier_xhosa, who sent me all this from Belgium), and the presence of a similar facility Iridium on board Olivier's boat : Iridium 9575 with fixed external antenna Sailor, we were able to test in real use.

Prince d'Oc vers la Croatie

Prince d'Oc en route to Croatia

Principle of implementation

Two types of tests were performed :

  • MacBook USB connection with Iridium and IsatPhone through GMN XGate application.
  • iPad 1 WiFi connection via GMN Redport Optimizer, featured onboard.

Three identical GRIB file queries have been made, file 32 KB compressed in all cases 27 KB by the same algorithm (bz2). In each case XGate application was used (MaxGate with MacBook and XGate with iPad). Two tests were carried out at anchor (in the Bouches de Bonifacio) and a navigation test. In all cases the tests are relatively similar.

IsatPhone et Iridium



The tests confirm the claims of GMN times in my previous post (¹) while specifying the real-time communication. The IsatPhone is penalized by the fact that the establishment of each connection requires 50 seconds up to 1 minute for calibration, probably the time that the satellite receives the GPS position to lock its mobile antennas, before transmitting data. Then transfer times are relatively similar.

We noted that the Iridium external antenna, Sailor brand, was particularly effective. Throughout the course, most connections have been completed successfully without using prediction tool satellite pass (²) in Weather4D PRO.

Costing the IsatPhone (³) was confirmed by the invoice received in July by the owner of the device. This shows, as mentioned in my previous post, that communication costs are significantly higher with Inmarsat than with Iridium. Especially the connection time, as receiving the file 27 KB, appears to vary considerably with the IsatPhone based on movements of the boat.

Hopefully, for holders of IsatPhone, that prices will decline in the future by the competition.

(¹) IsatPhone Pro versus Iridium, choose which ?
(²) Iridium Mail & Web : GRIB weather files on iPhone and iPad in open sea
(³) The price per minute are those of a prepaid card 500 minutes for both operators.


2 Replies to “IsatPhone Pro contre Iridium (continue)”

  1. hello

    In tests with your Mac at anchor and route you're talking about units of (actually 2), this means that the units are different iridium or ISAT ?
    In’ Data such as (on iridium), with a card 500 prepaid minutes, after your tests at anchor and navigation, has been charged to 4,40 Minutes of its 500 (2 Once 2m20s) therefore 4,40 minutes 54Kb effective transfer (2*27KB), is that right?
    Could you briefly we (me) explain billing iridium Data and voice ? THANK YOU
    The final one sending mail SkyFile of 10Kb, 50KB, 100How Kb cost ?
    D"in your opinion, what is the way to optimize the ratio in our emails Kb / price ?
    Have you a comparison of your test with those made under windows PC and SkyFile?

    1. The answer to most of your questions can be found in previous post regarding the choice Iridium / IsatPhone. On Skyfile, I am not able to answer, I dont mind that solutions Mac or iPad / iPhone.
      I can only say that any file> 45/50Ko require more than one pass Iridium, therefore an additional cost for each transfer resume.

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