-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Richard Bown wrote: > Time to stick my oar in ! > > A few facts as satellite coms are above 1 GHz, there will be no effect > on them > In a large solar event that was pointing directly 'at' us, it could destroy satellites and kill astronauts but these are both unlikely.
Satellites can malfunction during these events. Not all satellite coms are at 1Gc or higher, although most are much higher. (Often 14Gc or so going up, and around 12 Gc coming back down) The trend in newer satellites is toward higher freqs. but we still have a lot of stuff up there talking to us on the VHF and UHF bands. There are freqs in use in both the 2m (144Mc) and 70cm (440Mc) bands and radios being sold to work them : http://www.icomamerica.com/amateur/satellite/index.html You are probably refering to the commercial, communications satellites and I don't know all of the link frequencies for these but I think you are right about these being > 1Gc. > I'll explain why > > the increase in magnetic flux caused by a solar flare has several effect > 1. it changes the properties of the ionosphere, which short wave comms > relies on , hence the short wave black out. It increases the level of ionization and reduces the heights of the layers of the ionosphere. This reduces the skip-distance for frequencies below the MUF (maximum freq. that is reflected back from the sky, dependent on the angle of incidence of the signal with respect to the layer) and increases the MUF. Lower amatuer bands ([EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED]) that can normally be worked for long distances suddenly can't be since the layer that you are trying to reflect off is much lower, the skip distance shorter, the number of hops to get somewhere is higher so the loss gets higher. The noise level goes up also. 28Mc is good for local work only more of the time, under 'normal' conditions, than otherwise. When solar activity is (moderately) higher things change and 28Mc can be used for some impressively long distances. (I've worked Australia from the US using about 100W SSB and a simple 1/4 wave vertical antenna) When 'the skip is rolling' on the 27Mc CB band in the US local comm can become almost impossible, because of the noise level from distant stations booming in. It can take you more power to talk 5 or 10 miles than it does to talk thousands of miles. I've worked clear across the country with only 4 watts... > AM based transmission are very susceptible to this this includes TV > transmissions.. This visual portion of the TV signal is AM, the audio is FM. All of the parts of a given TV signal fit within a 6Mc wide band of frequencies. (US channel 6 is 82Mc-88Mc) The frequency of the signal makes a much bigger difference in this case than the type of modulation. The AM broadcast band is 0.55Mc to 1.7Mc. The FM broadcast band is 88Mc to 108Mc. The 'AM' band is always reflected by the ionosphere, the 'FM' band only during very unusual conditions. and AM radio. > FM transmissions are less susceptible but are still effected. > As the amont of doppler shift is randomised the tonal quality of speech > on a AM transmission will sound like a whisper. > TV pictures will be effected but not dramatically. TV stations, normally well out of range, may be received. This is generally a short-term effect though. > As for mobile phones, no effect as these are all short range comms and > are all above 800MHz and use either gMSK or WBCDMA. The telco's depend on leased satellite services to tie their sites and networks together. Skytel's service was wiped out for a day or so a while back, because of satellite problems. Local services can get disrupted by unusually high noise levels also. > Right time to stop boring the list I agree with you on this one also... at least we aren't talking about winders(tm). - -- KevinO If Microsoft built cars, If you were involved in a crash, you would have no idea what happened. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQE/mP59WOfRC7Rnmv8RAgjkAJ9bnnYbtpOh8EqNYTugmq/95kWIsQCeNvB4 1w5EpIqpL0IsLqvmea87Qnw= =8osT -----END PGP SIGNATURE-----
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