Scott Tilley

@coastal8049

Looking up to set myself free of other's alternative facts... Opinions are my own or anyone else's that take the time to look for themselves...

Roberts Creek, BC
Vrijeme pridruživanja: prosinac 2014.

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  1. Prikvačeni tweet
    22. lis 2018.
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  2. prije 18 sati
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  3. 4. velj

    Pretty darn cool gizmo these NanoVNAs! Good to 1500MHz and seems to work great on antennas I have here. This a dual band 2m/70cm handheld antenna. Now to tweak the antennas on the roof.

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  4. 4. velj

    Is anyone aware of active satellite ground station(s) in the Seattle area (NW Washington State) that may service missions on S-band?

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  5. 3. velj

    After an epic 'pineapple express' our community has had major disruptions to roads and property as run off waters undermine culverts and cause damming on local creeks flooding out homes. Our road access was severed for 24 hours yesterday. Thanks Hawaii :-)

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  6. 2. velj

    Nice one Daniel! The Salyut 7 recovery was simply the most awesome manned space event in my memory.

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  7. 2. velj

    Nuclear RTG geosat LES-9 continues to emit a CW carrier, not it's usual BPSK TT&C beacon. Since noting this on Jan 29th, no change in spacecraft status has been noticed. Here's a sample of what it normally sounded like until between Jan 13th thru 29th.

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  8. 2. velj

    Here's a week long comparison of the active Meridian constellation satellites in their fixed planes and the behaviour of Meridian 2 which is outside the constellation yet active. As you can see its apogee drifts around and it doesn't have a fixed ground track.

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  9. 2. velj

    developed the decoder to display these frames.

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  10. 2. velj

    Lastly, the Meridian 3 'GAP' is present on both apogees. launched into Meridian 3's orbital plane M8 has not demonstrated any operational behaviour on 278, 484MHz or X-band. Observations by have showed limited C-band activity from M8.

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  11. 2. velj

    The fact that Meridian 6 doesn't seem to comply with constellation behaviour is interesting as it could be the reason why Meridian 9 appears to be targeting this orbital plane and slot in the constellation and not Meridian 4 which is a much old satellite.

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  12. 2. velj

    Meridian 6 is an outlier that doesn't conform to these general observations. It simply jumps into the UHF apogee frequency and X-band unique frame ID upon start up. Note no opposite UHF transponder behaviour and absence of X-band start frame.

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  13. 2. velj

    Once the s/c makes the switch to a unique frame used only by that particular spacecraft, the UHF transponder switches to its respective apogee frequency. The timing of this switch is not exact for both bands but is very closely related. The image here provides a frame summary.

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  14. 2. velj

    The image above shows the sequence of the X-band beacon for Meridian 4 on start up. It starts with a carrier, then sends a generic frame used by almost all active Meridian's upon start up, on UHF 484 the opposite apogee freq is used.

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  15. 2. velj

    The behaviour of Meridian 4 and 7 is directly related to the X-band TTY beacon believed to transmit a space craft ID. Upon start up these spacecraft use the generic ID frame, but as the UHF transponder switches to proper apogee freq. The s/c ID becomes unique.

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  16. 2. velj

    Fifth, the sidereal locked mean motion of the satellites Meridian 4, 6 and 7 is clear in the animation. Indicating they are actively in the satellite constellation. Where Meridian 2 is clearly not drifting out of sync. Hence why it has it's own frequency for ease of management.

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  17. 2. velj

    Fourth, when Meridian 4 and 7 come on they appear to start transponder transmissions on the opposite apogee frequency. The image below shows Meridian 4 starting on Russian apogee frequency and switching to North American one a few minutes later. [sub thread]

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  18. 2. velj

    Third, on UHF even at my latitude of almost 50 degrees north I can hear the Russian apogee on UHF. The attenuation from trees etc are not a severe as on higher bands and allow for analysis of the signal. 483.75MHz is in use on the Russian apogee.

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  19. 2. velj

    Second, Meridian 2 which was placed into the wrong orbit due to a final stage malfunction during launch occupies the 484MHz slot all to it self as it slips in and out of sync with the rest of the constellation.

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  20. 2. velj

    First, the Meridian constellation uses the 484.25MHz slot for it's North American apogee. Where the spacecraft hover over North America for about 6 hours each.

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  21. 2. velj

    Russian Meridian military communication satellite constellation monitoring continues. More operational info has been gleaned from long term monitoring of the transponders on ~484MHz. As you can see from this animated GIF there's a lot going on here. [thread]

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