Reply With QuoteThanks vk6xlr,
My girlfriend reported only a couple of days ago that there was a disruption to her Foxtel service, & a Foxtel message came up, saying something about due to solar interference,
Solar conjunctions.
Solar conjunctions are/will be affecting our satellite receptions this month.
Just came home from shopping and one of my prized birds was missing
Went checked the dish, lo and behold, the LNB shadow was dead centre.
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Thanks vk6xlr,
My girlfriend reported only a couple of days ago that there was a disruption to her Foxtel service, & a Foxtel message came up, saying something about due to solar interference,
Last edited by OSIRUS; 12-09-09 at 07:59 PM.
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With eastern birds, it'll happen in the morning, western birds, the afternoon.Originally Posted by OSIRUS
So, of course, it will happen at different times depending where the bird is in the clarke belt.
OSIRUS (12-09-09)
Yes, about 10.30 - 11.00am Sydney Time it happened
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Solar outages occur twice per year, in the equinoxes, March and September.
Such outages are caused by the sun tracking the same position as the Clarke belt, the area over the equator, where all communications satellites are located. Outages occur for ten to twenty minutes, as the sun's radiation progressively obscures each satellite, one by one.
Solar energy, overrides or "blanks out" the signals coming from such satellites.
An excellent discussion is available at
Satellite Solar Outage or Sun Outage
- summary, overview or tutorial of the basics of what is a satellite solar outage or sun outage that occurs at various times of the year.
One problem that can occur with satellite systems is what is termed a "Satellite Solar Outage" or "Sun Outage". During a solar outage it may not be possible to receive the signal from the satellite, or alternatively the signal will be degraded.
Solar outages affect all satellite systems, and they are quite predictable and they arise from the basic physics behind the operation of a satellite system, and indeed any radio communications link.
Satellite solar outage basics
Satellite solar outages occur because the Sun which is a powerful broadband microwave noise source passes directly behind the satellite (when viewed from Earth) and the receiver with the beam directed towards the satellite picks up both the satellite signal and the noise from the Sun.
The degree of interference caused by a satellite solar outage varies from slight signal degradation to complete loss of signal as the downlink is swamped by the noise from the Sun.
Mechanics behind a solar outage
Mechanics behind a solar outage
For geostationary satellites, the solar outage can typically cause disruption to the received signal for a few minutes each day for a few days. The exact date, time and duration of such events depends on a variety of factors including:
* Receiver location
* Location of the particular satellite
* Size, or more specifically the beamwidth of the antenna
* The apparent radius of the Sun as seen from the earth (about 0.25°).
* Accuracy of alignment of the antenna direction towards the satellite
Parameters such as the antenna directivity can make large differences to the amount of time of the solar outage. Antennas with a very wide beamwidth could be affected for as much as half an hour, whereas antennas with higher gain and directivity levels as are more commonly used for satellite reception will be affected for much shorter periods of time. Typically only a few minutes.
The effect of the solar noise causing the outage is very marked. Even at times of low solar activity, the effect is very noticeable and can result in noise levels of between 10 and 20 dB above the signals from transponders, dependent upon a host of factors.
It is possible to defined what is termed and outage angle of the receiving antenna. The solar outage angle of the antenna angle is defined as the separation angle (measured from the ground station antenna) between the satellite and the Sun at the time when sun outage or signal degradation begins or ends.
It is not always possible to exactly predict the duration of a solar outage. The exact point at which the solar outage begins and ends is a gradual transition. In addition to this there are many differences between different installations and systems. Accordingly some stations may experience a complete loss of signal while others may only experience a tolerable degradation of signal. In view of this it is not possible to exactly determine the exact solar outage angles without complete information about the ground station equipment and the satellite parameters. However an approximation can be gained from the following equation:
Outage angle = 11
(Frequency) x (Diameter) + 0.25°
Where (Frequency) = Downlink Frequency in GHz
Where (Diameter) = Receiver parabolic reflector or dish antenna diameter in metres
When do satellite solar outages occur
For geostationary satellites, solar outages occur around the equinoxes, i.e. March / April and then again in September / October. At these times of year the Sun crosses the equator and it traces an arc that places it directly behind geostationary satellites.
It is found that the in the Northern Hemisphere, solar outages usually occur in early March and October as a result of the geometry and relative positions of satellites and the solar transit of the Sun. In the Southern Hemisphere, outages normally occur in early September and April. The time of day varies mainly with the longitude of the satellite and receiving station, while the exact days vary mainly with the station's latitude. Stations along the equator will experience solar transit right at the equinoxes, because the satellites in geostationary orbit are located directly over them.
The exact dates and times of the solar outages are easy to predict and many calculators are available. All that is needed is a knowledge of the satellite position (sometimes just the satellite is needed as its coordinates may be held within the calculator), the position of the receiver in latitude and longitude. The beamwidth of the antenna is often needed as it will enable the time of the satellite solar outage to be determined.
Summary
While satellite solar outages, or satellite sun outages can be annoying, they are normally short lived and they are totally predictable. They affect all satellites, and in particular these solar outages are commonly experienced as a result of the widespread use of satellite direct broadcast TV reception. However all satellites are affected, whether geostationary or in other orbits, and the effects can cause short lived disruption to the radio communications.
BillyGoat (14-09-09),gordon_s1942 (14-09-09),gulliver (14-09-09),mohan76 (13-09-09),OSIRUS (12-09-09)
The same happened to me yesterday,Saturday at 2.30 pm.I was checking Chinasat6b and all of a sudden, all chanels had no signal.I went outside and saw the shadow right in the centre,got inside ,took the camera and took a picture of it. Went inside and all was back to normal at 2.35 p.M. Sydney time.( mod.why can't I post attachments????)
Last edited by gulliver; 13-09-09 at 06:36 PM.
No-one can post attachments, they need to be hosted at an external site and displayed in the forum using IMG tags. If you check below the thread there is am area called "Upload your images to ImageShack", click the browse button, find the image on your PC then click host it. A new page will open and copy the url in Thumbnail for forums (1). Paste this url in your post.
I hope this works and thank you very much for your help and explanations ssrattus.
BillyGoat (14-09-09)
Ahh, now the yearly barage of phone calls from the little old Italian, Spanish and Portuguese women. If it was only 30 years earlier.....
30 years ago you wouldnt have known what to do with it.......................OOOOHHH, you mean THEM ????
sorry bout that. heheheheheh
Happened to my C Band dish on Telstar 18 3559Ghz for two consecitive days last week.
First day at about 2.00pm to 3.10pm lost signal/level down to 18%, no pics.
Next day about same time only went down to 35% with pixalization,broken pics.
Sat is AZ 328deg, EL 55.6deg to my house, NW direction probably straight into the Sun as you say.
Didn"t know this could happen. Will take a look tomorrow at that time to check the sun angle.
you like hairy women do youAhh, now the yearly barage of phone calls from the little old Italian, Spanish and Portuguese women. If it was only 30 years earlier.....
Yeah, the portuguese women are actually Brazilians.
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