Satgen104    HF Supersats II     by GM4IHJ      22nd March 1991

Thanks for all mail and questions on this subject. It is good to know that
so many people worldwide are interested in the subject of long range sub
horizon HF satellite propagation using quite simple ground station
equipment. Contrary to some opinion, this is not a new subject. It began
when Sputnik 1 orbited the earth in 1957 , with its HF beacon signal being
heard in UK and USA when Sputnik was on the opposite point of the earth (
antipodeal ) to the receiving stations. When Amateur Oscars came along ,
more data was added particularly by Oscar 6 (1972/1976) and the long
series of RS1 to RS8 added even more data in the 1980s.

If you check old papers on the subject you will read of the gradual
acceptance than these long range sub horizon contacts can be predicted.
Cosmos 1686 was particularly useful in this respect because it used a
19.955 MHz beacon which propagated very effectively at both sunspot
minimum 1986 and sunspot max 1989/90 , flying for two years at 340 kms
height and then moving up to 440 kms for the last three years.

More recently RS10 has been heard regularly this last year or so when
10,000 kms from UK. Following its progress from UK has made interesting
comparisons with concurrent HF terrestrial signal propagation particularly
as it flew over and west of South Africa in our UK afternoons and early
evenings when the satellite was just east of the Greyline Day/Night line
in the ionosphere near the satellite. Very few of the signals were tone 9
. Most were about tone 4 with almost none tone 1.

There is lots of interesting historical and general propagation data in
the following publications :-

Proceedings of IRE (USA) for 1958/59 particularly March 58 by Owen Garriot

Getting to know Oscar (ARRL) page 23

Satellite Experimenters Handbook by Martin Davidoff Edition 1 page 10-6

Orbit Magazine Amsat NA Jan/Feb 81 page 4 by W2RS 

IERE Journal (Brit) Aug 82 page 411 Uosat data on phase locked receivers
for harmonically related beacon studies.

Practical Wireless Sept 87 page 32 shows some antipodeal results
See also Pat Gowen's regular columns in PW for more reports

Radio Communications Nov 89 page 25 shows how doppler measurement can
enhance these studies.

Most of all , keep listening. Both RS10 29.357 and RS12 29.408 MHz are
radiating beacon telemetry at the moment. 73 de John GM4IHJ @ GB7SAN