Inmarsat 25 Degrees East

[Radioman712000]

Hi guys have Been having great fun listening to voice calls from inmarsat 25 degrees east from The United Kingdom in kent . My observation is this its very very active with every couple of minutes voice is coming through . I took note that most of the calls are non English language? Is there any reason for that ? My working equipments are rtl patch antenna, RSP1B using sdruno .

 

[littona]

I'd think that has a lot to do with the customer base. Consider who has access to a reliable cellular infrastructure and who doesn't.

• The satellite is designed to cover the Europe, Middle East, and Africa (EMEA) region.
• The consolidated/global beam spans:
  • All of Europe
  • Most of Africa (north, central, and much of southern)
  • Middle East into western Asia
  • Atlantic and Indian Ocean edges adjacent to these landmasses

 

[jom79]

I have always wondered why 25E with its huge coverage only has 6 voice channels when 54W has well over 40.. I have seen all 6 channels occupied at once.

Does the 54W satellite have an insane amount of voice traffic compared to 25E? Or is it just the fact that it covers most of the Atlantic ocean where there is no other coverage?

John

 

[Radioman712000]

I have always wondered why 25E with its huge coverage only has 6 voice channels when 54W has well over 40.. I have seen all 6 channels occupied at once.

Does the 54W satellite have an insane amount of voice traffic compared to 25E? Or is it just the fact that it covers most of the Atlantic ocean where there is no other coverage?

John

Hi John I have only seen 3 so far from London in England UK. Will it be possible to share those 6 channels with me ?

 

[dlwtrunked]

Hi John I have only seen 3 so far from London in England UK. Will it be possible to share those 6 channels with me ?

6? The place to look for frequencies for this is https://acars-vdl2.groups.io/g/main/attachment/6442/0/INMARSAT frequency list.pdf
Sergei coordinated putting it together. I helped. Spread throughout the globe, we did not just listen for voice, we decoded controlling data. It was complete at the time.

 

[jom79]

Hi John I have only seen 3 so far from London in England UK. Will it be possible to share those 6 channels with me ?

I used the frequency list on the bottom of this page:
How to build an L-Band ground station.

I have not seen more than 6 8400bps voice channels. Are the 21000 bps LPC channels around 1545 active? If so is there a decoder available for them?

John

 

[Hutchp]

I have always wondered why 25E with its huge coverage only has 6 voice channels when 54W has well over 40.. I have seen all 6 channels occupied at once.

Does the 54W satellite have an insane amount of voice traffic compared to 25E? Or is it just the fact that it covers most of the Atlantic ocean where there is no other coverage?

John

Hi
The 54w satellite using multiple spot beams rather than the Global beam on 25E hence lots of voice channels required on 54W. That being said 54W is an old legacy satellite. There is very little voice traffic on it now. The bulk of the traffic for that region is across the 98W and 25E satellites as there is quite an overlap on the footprint.
In the gap on 25E between the lower 3 voice channels and the upper 3 channels is the I-6F1 83.4E voice traffic. Using a very large C band antenna I have occasionally locked to voice traffic in these slots.

BTW for dlwtrunked, in the freq. list you have a typo . The Inmarsat I-4A-F4 is at 25E not 25W. If you are interested I have all the C band voice channel frequencies and transponder translation freqs for 25E

Forgot to add the 21000bps are active , RAF A-400 aircraft are frequent users for example. Not decodable with Jaero is all I will say on that.

Hutch