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Scott Tilley 🇺🇦 Profile picture
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Mar 12 • 4 tweets • 2 min read
Russian military MERIDIAN 7 C-band this evening. There's now a 100KHz non-regenerative transponder on the band. I've seen these appear rarely on X-band but until now not on C-band.
MERIDIAN 7 with the usual TTY beacon on 3610MHz.
Here's what I think is the MERIDIAN 7 regenerative transponder. ~500KHz wideband data on 3625MHz.
The MERIDIAN 7 upper TTY beacon (marker). 3640MHz. Like X-band the upper marker is much weaker than the lower marker.

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More from @coastal8049

Scott Tilley 🇺🇦 Profile picture
Mar 6
Here's how to understand the RADAR data I'm sharing.

The Russian MERIDIAN satellites are in High Earth Orbit and have their apogees fixed above the Northern hemisphere over Russia and North America. This allows the spacecraft to see both places at once.

THREAD
1.
Being in a highly elliptical orbit the MERIDIAN satellite is actually visible to observers on the opposite side of the world at a very low elevation in their sky. Here's an example plot of simulation of MERIDIAN 8 at the North American apogee visible from Ukraine.
2.
Examining geometry you can easily see that the satellite is visible to both stations in North America and Europe/Asia. The geometry below is when MERIDIAN 8 is setting over Ukraine. Satellite footprint is the yellow circle on the Earth. Anything within that can see satellite.
3.
Read 8 tweets
Scott Tilley 🇺🇦 Profile picture
Mar 5
Some details on what is known about the MERIDIAN 990MHz transponder system. This transponder seems to be a legacy of the older Soviet MOLNIYA system as evidenced by this excerpt from a report to the US congress in the 1980s.
THREAD
When the last of the MOLNIYA's were still operational amateurs noted transponder activity from them while the spacecraft were on the Russian/European apogee. But by 2011 MOLNIYA went silent and was replaced by MERIDIAN and during the gap no one looked...
Amateurs lost track of the 990MHz transponder and it wasn't until the Breakthrough Listen Candidate 1 signal was reported on 982MHz that I began searching the band in an effort to determine if there was satellite activity that we noted there actually was.
Read 15 tweets
Scott Tilley 🇺🇦 Profile picture
Mar 4
It's March 4th.

Today a piece of humanity's cast off technology will impact the Moon in a event that would have gone unnoticed had it not been for the work of a few folks looking up in unpaid and normally unnoticed toil... (1/4)
In order to explore the Moon and for all of humanity to share in the potential positive aspects of that exploration and utilization we need to be able to monitor activity around the Moon in a more transparent and accessible way.

(2/4)
We shouldn't need to rely on the reports of amateurs, astronomers focused on other research and defence systems focused on other priorities. We need a focused cislunar space situational awareness asset to enable humanities growth in this realm.

(3/4)
Read 4 tweets
Scott Tilley 🇺🇦 Profile picture
Feb 27
Based on research here's the layout of Russian military satellite communications at this time from Ukraine. 1st image is a sky view as you would see it from ground looking at the GEO satellites, 2nd a chart view of all assets visible and 3rd a map view. (1/n) ImageImageImage
Understanding where command and control assets would need to view these satellites limits their tactical options to hide and helps one hunt them. (2/n)
More skyview perspectives showing all assets with elevations and azimuth grid on. ImageImage
Read 5 tweets
Scott Tilley 🇺🇦 Profile picture
Feb 27
A primer on the Russian military's MERIDIAN satellite constellation.

MERIDIAN is an High Earth Orbit (HEO) Russian military satellite designed to provide communications to northern latitudes (I.e. Russia et. al.). It is a modern version of the MOLNIYA constellation. Image
The MERIDIAN constellation is primarily designed to offer communications to high northern latitudes where access to GEO satellites could be difficult or impossible.
MERIDIAN satellites are known to operate on the following bands:
~279MHz, 484MHz, 990MHz (non-regenerative)
TT&C ~3410MHz
3400-3900MHz and 7500MHZ (+/- 80MHz) regenerative transponders.
Russian Geostationary assets are known to mirror these transponders to some extent.
Read 4 tweets
Scott Tilley 🇺🇦 Profile picture
Feb 26
This could be very well be a beacon of hope, the sound of resistance that can be heard around the world.

Russian military satellite MERIDIAN 8 reveals radar emissions that most are coming from Ukrainian forces defending themselves. After days of onslaught Ukraine stands.
Multiple RADAR signals are being heard.
Read 4 tweets

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