VSAT Sun Outages

What is a Sun Outage?

A sun outage (or sometimes called a solar transit event or sun fade) happens twice a year during the equinox in March and September, when the Sun is directly above the Equator. Each outage lasts for several minutes for a few days and is caused by the satellite passing directly in front of the Sun as the Earth rotates.

 

Satellite Sun Outage

The antenna can see the Sun behind the satellite for these short periods, and the LNB receivers are briefly overwhelmed with radio noise (RF) from the Sun. The noise floor of the link will be increased swamping out the signal from the satellite for a few minutes. This might cause a total outage of communications or poor throughput depending on the robustness (MODCOD, power) of the link. All frequency bands experience increased RF noise.

Larger dishes (normally at the teleport/hub end) have a narrower, more focused beam and experience shorter outage periods, repeating over a shorter number of days than smaller antennas. But an outage of the hub antenna will affect multiple customers, while an outage at the remote VSAT antenna only affects the link on that antenna.

So, this means each VSAT communication link will experience two sun outages per equinox.

A 2.4m C-band dish will typically see about 11-minute outages daily, recurring at the same time
over the course of a week. The outage time will peak in the middle of the outage cycle.

How to calculate your outages

Enter the antenna location coordinates, frequency band and size for both antennas.Sun Outages can be calculated using web tools, such as this tool.

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    […] link performance are due to atmospheric conditions like rain (rain fade), changes in the RF levels, solar events, noise or interference. Previously these conditions could result in the link dropping out of […]

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