© Electronic Systems Laboratory 1999
by Buchan Milne
WWW:sunsat.ee.sun.ac.za
Last week end (6 June), good strength amateur signals (particularly from ZS1CT) were heard on the first afternoon pass. On the second pass, no activity from amateurs was apparent. The Sunsat transponder was functioning, broadcasting noise from the uplink receiver.
13 June
transponder passes
13:21 to 13:35
15:01 to 15:12
(Monday morning 14 June)
00:31 to 00:44
02:10 to 02:22
Announcement of amateur transponder service passes starting 30 June
SUNSAT in-orbit testing has reached a stage where it is possible to make more time available for South African Amateur Radio use of SUNSAT, and to let our ground station teams spend more week-end time with friends and family.
Our normal plan will thus be to program SUNSAT to support South African Radio Amateur transponder mode operation during passes starting late Saturday evening and ending early Monday morning. SUNSAT will thus activate its 436.291 MHz receiver and 145.825 MHz transmitter during these South African passes. The transmitter will be continuously keyed, and be NBFM modulated by the the receiver's audio output.
The 2m transmitter should give a good signal on hand-helds, which is a benefit of operating UHF up, VHF down (mode J reversed). Previous tests used a 145.950 MHz uplink and 436.25 MHz downlink, but we believe the new plan will enable more amateurs to hear SUNSAT than if we use the UHF downlink.
We uplink to SUNSAT with a 20W transmitter and 9 turn (13dBc?) tracking RHCP helix antenna. We would be keen to hear what EIRP other people use to get in to SUNSAT's UHF receivers. Pass predictions as seen from Stellenbosch are on http://sunsat.ee.sun.ac.za. This week end's transponder operation passes are: