Satgen 555 Track RS13 SubHorizon  by GM4IHJ  (BID SGEN555)  1999-11-13

While the present rise in solar output does not seem likely to reach
the heights attained in the previous cycle 88/89 ( Sunspots 150, Solar
Flux 200)). Results so far in respect of subhorizon access to
satellite RS13, have been good enough to suggest that we are going to
have an interesting northern hemispheres winter DX. But if you are to
get good results, you have to be lucky, and you have to be able to
appreciate how the gradual daily shift west of RS13s orbit plane ,
affects when and where ,you hear the satellite and, who you may be
able to contact through it.

As regards operating technique, CW is king. Meaningful SSB qsos are
all but impossible presently, and this will not improve unless there
is a marked increase in solar flux. There are 3 reasons for this CW
only, statement at the moment. Firstly signals coming from subhorizon
locations are rarely if ever tone 9. T1 or T2 signals are much more
the daily fare at this time. Secondly signal propagation is highly
variable. For example recent reception from RS13 when it was south of
Adelaide in Australia , was doppler shifting 150 Hz in just over 1
minute, then jumping back 150 Hz and staring the downward doppler
drift all over again. Experience in previous solar cycles suggests
this is a feature caused by the marginal solar flux. In previous
cycles the signals have been much less disturbed. However if the solar
flux does improve, the third problem will get worse. Mornings on 29.46
to 29.5 searching for signals are already being shattered by Russian
FMers. Whilst afternoons are being blasted by FMing Gs , EAs, DLs,
9H1s , Ws and VEs. None of whom have ever heard of band plans. 

But all is not lost provided you can second guess where the signals
will be propagating from, get on a narrow band filter and screen out
much of the QRM. Then given RS13s westward shift this has meant,
signals in early October afternoons utc coming to GM from the Easter
North Pacific. By end October these afternoon contacts were fom the
North West Pacific , and now in mid November, they are coming from the
Indian Ocean, unfortunately hopelessly disturbed as they pass west of
Perth Australia going north.

Here in Scotland the winter days are getting shorter and shorter. Dawn
is around 0800 and sunset is around 1600, but in spite of this the DX
comes in even when RS is flying over the the night side of earth
beyond the terminator. RS can get at least 3000 kms into the night
side and still see the underside of a sunlit ionosphhere. So no one
should be surprised by predawn or post sunset contacts . Indeed whilst
discussing the solar terminator it is worth pointing out that for
reasons which are not at all clear , RS13 sometimes tracks across
antarctica in silence until it crosses the terminator into the night
side heading east. It then quite often begins to put good signals into
GM with very little distortion for several minutes. A trick which can
occur on up to 3 successive orbits. Unfortunately these good signals
have a disasterous habit of disappearing completely just before the
satellite reaches VK or ZL. Please note however that doppler shift on
these signals usually suggests that they are coming by non great
circle paths.