Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 13-11-2019, 12:40   #16
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 3,651
Send a message via Skype™ to Auspicious
Re: Iridium Go Reception

Quote:
Originally Posted by Snore View Post
First did some more testing. If you know the longitude, you can orientate the small antenna to “see” that way. This allows 5-bar coverage for longer periods. I will be putting the longitudes of the orbits in the front of my log book.
Wellll... *grin*

The Iridium constellation is inclined at 86.4° (Globalstar is inclined at 54°). That's the angle each of the six orbital planes of eleven active satellites crosses the equator. So you can use that number to aim a directional antenna parallel to the orbital planes. To my knowledge the planes, 30° apart, march around the planet. The longitudes are not constants to my knowledge. Accordingly you need a dynamic model using ephemerides to adjust within the bounds of +/- 15° to point at the place on the horizon where the satellites rise, stay pointed as the satellite pass, and be pointed where the satellites set. That's a lot of work. Add in the fact that while scheduled maintance is performed over the poles repairs and unscheduled maintenance may take any given satellite off line. In those cases the strongest signal may come from a satellite in an adjacent plane. On the basis of good system engineering Iridium external antennas are omnidirectional in the horizontal plane with most gain on the horizon and less as elevation increases. In short, the only role for any directionality in a Iridium or Globalstar external antenna is if you have a very fast fire control pointing system like those of KVH TV and Inmarsat antennas.
__________________
sail fast and eat well, dave
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Old 13-11-2019, 13:02   #17
Marine Service Provider
 
Snore's Avatar

Join Date: Jan 2011
Location: St. Petersburg, FL
Boat: Retired Delivery Capt
Posts: 3,683
Send a message via Skype™ to Snore
Re: Iridium Go Reception

Quote:
Originally Posted by Auspicious View Post
Wellll... *grin*



The Iridium constellation is inclined at 86.4° (Globalstar is inclined at 54°). That's the angle each of the six orbital planes of eleven active satellites crosses the equator. So you can use that number to aim a directional antenna parallel to the orbital planes. To my knowledge the planes, 30° apart, march around the planet. The longitudes are not constants to my knowledge. Accordingly you need a dynamic model using ephemerides to adjust within the bounds of +/- 15° to point at the place on the horizon where the satellites rise, stay pointed as the satellite pass, and be pointed where the satellites set. That's a lot of work. Add in the fact that while scheduled maintance is performed over the poles repairs and unscheduled maintenance may take any given satellite off line. In those cases the strongest signal may come from a satellite in an adjacent plane. On the basis of good system engineering Iridium external antennas are omnidirectional in the horizontal plane with most gain on the horizon and less as elevation increases. In short, the only role for any directionality in a Iridium or Globalstar external antenna is if you have a very fast fire control pointing system like those of KVH TV and Inmarsat antennas.


Ahhhh weedhopper patience. Read entire thread

Corrected myself when I was writing it up. There are apps that allege they track the iridium sats- but do not tie with websites. The websites show more sats.
__________________
"Whenever...it requires a strong moral principle to prevent me from deliberately stepping into the street, and methodically knocking people's hats off- then, I account it high time to get to sea..." Ishmael
Snore is offline   Reply With Quote
Old 13-11-2019, 13:32   #18
Registered User

Join Date: Oct 2015
Posts: 2,007
Re: Iridium Go Reception

Quote:
Originally Posted by Snore View Post
Well- I took the leap and purchased an Iridium GO.

To get familiar with it before heading out on some deliveries, it is being tested on my personal boat. Reception appears to be wonky. On a calm day, below decks I can have 5 bars of strength, then two and then it is searching for satellites.

Thinking it was an issue with being below decks, I moved the device up on deck. Clear view of sky, light clouds- same results. I then purchased what was supposed to be a "Good" portable antenna, the stubby black one (see below). There appears to be no significant improvement.

https://www.bluecosmo.com/iridium-po...RoCBPgQAvD_BwE



Any tips from you guys running GO devices? The mast mounted antenna on an upcoming delivery will likely be better. But for now I am working on getting the portable package that will be used for deliveries more efficient.

thanks
As an additional thought to the others you have gotten: We have had a our Go! for over 5 years, and never had a connection problem anywhere while underway, and we used it a lot to up- and down- load data from the Eastern North Pacific to the North Atlantic.

BUT... we consistently get poor to mediocre reception in marinas. We never actually try to use it in marinas, but we do keep it on so our position gets updated and pinged to our blog site. It frequently loses connection and needs to find a satellite link again. Something that very rarely happens underway.

I could speculate as to why this is true, but it would be just that, speculation.
billknny is offline   Reply With Quote
Old 13-11-2019, 14:40   #19
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 3,651
Send a message via Skype™ to Auspicious
Re: Iridium Go Reception

Quote:
Originally Posted by Snore View Post
Ahhhh weedhopper patience. Read entire thread

Corrected myself when I was writing it up. There are apps that allege they track the iridium sats- but do not tie with websites. The websites show more sats.
I often get distracted when I start a reply and it may take me a few hours to actually post.

There are a number of hot spare satellites in orbit. They're up a little higher so they orbit more slowly. That means with some planning they can time dropping a satellite down into the active constellation. I think there are eleven spares in orbit but that may be based on the original Iridium plan (77 is the atomic number of the element iridium which is where the name came from). The spare satellites are probably what you are seeing on the websites. <- speculation on my part as I don't know what you are looking at.

Remember all this is radio - just like GPS, WiFi, VHF, HF/SSB, Bluetooth, microwave ovens, garage door openers, ad infinitum. See https://www.ntia.doc.gov/files/ntia/...3-allochrt.pdf
__________________
sail fast and eat well, dave
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Reply

Tags
iridium, reception

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale: Iridium 9505a and Iridium 9555 sat phones Renewal Classifieds Archive 2 26-08-2013 18:10
Iridium 9555, Iridium Extreme or IsatPhone Pro? svseachange Marine Electronics 10 23-03-2013 08:02
Iridium Phone - ISatPhone Pro VS Iridium Extreme Fauvel Navigation 1 24-12-2011 10:47
Testing SSB Radio Reception Loose Ends Marine Electronics 33 27-09-2006 16:26
HF/SSB selection and reception Rick B. Marine Electronics 10 08-08-2006 11:07

Advertise Here


All times are GMT -7. The time now is 02:23.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.