Satgen 115   Radio Sport RM1 Oscar 21 Mode B   by GM4IHJ  9th June 91

RM1 has been on mode B lately using transponder No.2 with beacon at
145.948 , uplink 435.123 to  435.043, downlink  145.866 to 145.946  MHz
Performance seems as good as old Oscar 7. Have been working out just when
to try for US DX. States from Maine, Vermont, N York, N Jersey,
Maryland,Delaware , Virginia, the Carolinas, Georgia and (just) Florida,
should be in range. Plus, more westerly states out to the Dakotas,
Minnesota, Iowa, Illinois, Kentucky and Tennessee at extreme edge of
footprint. Possible American orbits marked below by  * .
         1991 ORBIT WINDOW OF RM1 . VERY APPROX ORBIT TIMES
 0 UTC 2 time4     6ut   8ut  10ut  12ut  14ut  16ut  18ut  20ut  22ut  24
 .3    4*    5*   6.    7.   8 .  9  . 10* . 11* June Orbits .  1  .  2  .
 . 4*  . 5*  .6    .7    8     9   10*    July Orbits  . 1   . 2   . 3   .
 .   7 .  8  . 9   10*   .  August Orbits  . 1   .2    3     4*   5*    6.
 .   10*  11* September Orbs 1 .  2  .  3  .  4* . 5*  . 6   .7    8    9.
 .October Orbits  1.   2 .  3  . 4*  .5*   6    7.   8 .  9  . 10* . 11* .
 .Orbit.1    2    3.   4*.   5*.  6  . 7   .8    .9    .10*  .11*  Nov   .
 .  2  .  3  .  4* . 5*  . 6   .7    .8    9    10*  11* December  . 1   .
..........................................................................

To use the above chart , please note that RM1 has 10 or 11 orbits in range
UK each day . These orbits are about 109 minutes apart and occupy an orbit
window about 18 hours wide. Because of perturbation of the RAAN the window
drifts about 7.3 minutes earlier each day. The orbits in the window are
numbered consecutively. So orbit one always has roughly the same path but
occurs gradually earlier week by week. The next table details roughly what
each orbit covers. So by using these two tables you can predict what sort
of DX to expect each day . Eg Orbit 1 occurs in September 91 sometime
around 0900 and as shown below, East Africa is in range at the start of
orbit 1 and the Arctic is in range at the end of orbit 1.By contrast orbit
6 in June 91 occurs around 0600 ut and starts with Eastern Canada in range
and finishes with the Soviet Arctic in range, all at very low northern
elevation with high arctic absorption.

                  DX LOCATIONS ON RM1 ORBITS
Orbit No.     Begins UK in range of   Middle     Ends UK in range of
1                East Africa         Caspian      Soviet  Arctic
2                West Africa         Europe       Soviet Arctic
3                West Africa         Europe       Sov + Alaskan Arctic
4               *North East USA   Western Europe  Arctic
5               *Eastern USA       Scandinavia    Soviet Arctic
6                Eastern Canada    Scandinavia    Soviet Arctic
7                Hudson's Bay      Scandinavia    Persian Gulf
8                Hudson's Bay        N Europe     North Africa
9                N Alaska            N Europe     West Africa
10               N Alaska            *NE USA      Newfoundland
11               Canada             *East USA    *Florida to S Dakota

Note ......... Orbit 11 does not come in range of UK every day .Thanks to
all for excellent blather at Mid Lanark rally. 73 de John GM4IHJ @ GB7SAN