Sirius Weather Service

[mikepremiere]

Anyone out there have any experience with using the Sirius weather service, and what do you think about it?

[Pblais]

The only serious issue is the reception is limited to within 100 miles of the lower 48 states. If you mainly travel in that area then it should be very nice to have it.

[TritonSailor]

I was looking into it to supplement my Raymarine E80 Nav set, but you have to put out some serious money just to use the service. For my Nav set, I would have to spend $1000.00 just for the receiver. I think I'm going to stick with radiofaxes and forcast's. What happens when I want to cruise the Carribbean, or head for the South Pacific via the canal. It looks very pretty, but like Paul said, if your going to be cruising beyond the coastal range of the US, then why bother.

Thanks

Jeff

[mikepremiere]

I agree but I though that since it was sat based it would work like your GPS everywhere. Why only 100 mile max

[TritonSailor]

I'm only guessing here, but maybe the satellites are in geosynchronous orbit and are only for the continental US and just happen to extend that far out in the ocean.

Jeff

[GordMay]

Both Sirius & XM Satellite* radio are intended (and licenced) to provide service to only North America.

Siruis utilizes inclined elliptical geosynchronous orbiting satellites, which provide a larger coverage area than XM’s geostationary satellites.

Neither system actually “turns off” their up-down link at the equator ~ the satellites just lose their line-of-site.

Notwithstanding, as currently configured, Sirius is generally available through Mexico & Pueto Rico, while XM has an even smaller footprint.

Satellite Radio Coverage Maps:
http://www.dogstarradios.com/sirasasecoma.html

All communications satellites are space-based repeaters that receive an uplinked signal, which is translated to another frequency and retransmitted back to earth.

There are two basic ways to cover a given area with satellites. The traditional approach is to put up a geostationary satellite over the desired area. Geostationary satellites are put into a circular orbit around the equator about 22,300 miles from earth. In such an orbit, the satellite speed matches the rotation of the earth, so the satellite is always overhead to any observer or station on earth. Sirius' competitor XM Radio uses this system with two satellites providing full U.S. coverage. The equatorial geostationary orbit is unique and currently jammed with satellites side by side only a few degrees apart. As with the frequency spectrum, we're simply running out of space.

Sirius takes the other approach of using elliptical orbits. The company has three elliptical orbits over the U.S. They are geosynchronous, meaning that their rotational period is 24 hours just like a geostationary satellite. The satellite apogee (high point) is 29,200 miles over Canada and the perigee (low point) is 14,900 miles. The orbits function in a way where two satellites are over the U.S. at all times. The satellites are spaced eight hours from one another, and each satellite is over the U.S. for about 16 hours. All three transmit the same data.

The elliptical orbits offer the advantage of a very high angle of coverage. With a conventional geostationary satellite, the line-of-sight path runs at a very low angle of elevation above the equator (about 30̊) to the south from the U.S. Because microwave transmissions are direct-line-of-sight, signals from geostationary satellites encounter many more obstacles like trees and buildings. With elliptical orbits, the satellites are more directly overhead (always above 60̊) and thereby avoid most earth obstacles. Yet at such distances, the attenuation from satellite to earth is enormous.

Under current international satellite-licensing regulations, a geostationary orbiting satellite has priority over a non-geostationary orbiting satellite.

[Sunset]

Originally Posted by mikepremiere

Anyone out there have any experience with using the Sirius weather service, and what do you think about it?

I have been using Sirius on my Raymarine E80 chartplotter for two years. It was installed on the boat when I bought it. I really like it, especially in the Bahamas where NOAA wont come in on the VHF. Since I mainly sail in Florida and the Bahamas the range is not a problem. I was able to get reception all the way to the Jumentos in the Bahamas so I believe 100 miles might be a little low.