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XM1 keps and footprint



Somebody wrote:

The xm1 and xm2 satellites are on the air, xm1 at 85 west provides some pretty strong data carriers, at 2333.5 and 2444.5 at -52 dbm, noise -87 at that wide bandwidth.
Just turned over to xm1 in a 3khz bw (about a 1 meg bandwidth to the carrier)
So this signal is 25 db stronger than ao40 ought to be good for some testing or something.

Wayne replies:

This is great!  Geosynchronous satellites are easy to find because they have a fixed  Az/El for any given location and there is no Doppler, but I still want my tracking program to tell me where to point the antenna.  So I found the keps on TS Kelso's web site.

XM-1                    
1 26761U 01018A   01185.28344152 -.00000211  00000-0  00000+0 0   856
2 26761   0.0517 168.7279 0001025 339.1506 151.3995  1.00270197   642

The footprint covers all of the Americas except the northwestern third of Alaska.  It also covers Hawaii, most of the Atlantic Ocean, plus Portugal and Westernmost Africa (the edge of the footprint passes through eastern Morocco, and eastern Ivory Coast).

The 2444.5 MHz signal is very convenient because I can receive it with my FT-847 and TranSystem downconverter (original crystal, 2278 MHz L.O.).  The 166.5 MHz IF frequency is in the tuning range of my FT-847.  If I had swapped the crystal to move the L.O. to 2256 MHz, then neither XM1 signal would be within the tuning range of my FT-847.

It will be great to have (in the Americas, anyway) a consistent signal to verify operation of S-band receiving systems.  No need to worry about varying range, squint angle, or Doppler.  It's even better than sun noise because the signal is much stronger and is available even at night.

Wayne Estes W9AE
Mundelein, IL, USA
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