SNR and equinoxes.

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belter-one
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SNR and equinoxes.

Post by belter-one » Tue Sep 24, 2019 11:23 am

Hello,

I have noticed that our maximum SNR on NASA 127W has gone from 14.8 to 15.8, over the past week, which includes the fall equinox. There is a transponder on 123W which also peaks at 15.8 SNR. Since the true azimuth of the clarke belt lies somewhere between these two satellites I am assuming that our dish is aligned correctly with the azimuth. So does SNR tend to increase by about 5% around the equinoxes and perhaps decrease by 5% around the solstices?

Quite fascinating,

belter-one

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Re: SNR and equinoxes.

Post by tek2000 » Tue Sep 24, 2019 2:07 pm

belter-one wrote:
Tue Sep 24, 2019 11:23 am
So does SNR tend to increase by about 5% around the equinoxes and perhaps decrease by 5% around the solstices?

Quite fascinating,

belter-one

No, it should do the opposite and decrease. Remember, during the equinox and solstice, the clarke belt plane which holds the satellites is coincident with the sun's equatorial plane. This means the sun will be directly behind some satellites and overwhelm their communication signals with random noise. Just before sunset, aim your dish at the most westerly satellite and monitor your signal strength. It should go from maximum to minimum and then back to maximum in about 15 minutes. The satellite operators publish tables by location showing the dates of when to expect the worst interference.

Fascinating indeed!!
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Re: SNR and equinoxes.

Post by rusty » Wed Sep 25, 2019 8:30 pm

12' Cosmos Primestar (refurbished)36" SuperJack Actuator
Chaparral Corotor Feed (Norsat 8115, 4106A)
ZGemmaH7 UHD, OctagonSX88 HD, Edision UHD, DSR-6000, DSR-6050
Clarke Belt: 22W - 133W

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