SUNSAT LEWER NOU OOK DIGITALE DIENSTE AAN RADIO-AMATEURS

Sunsat Oscar-35 is 'n mikrosatelliet wat tussen 1992 en 1998 aan die
Universiteit van Stellenbosch ontwikkel is.  Die satelliet is op 23
Februarie 1999 met 'n Delta II vuurpyl vanaf die Kaliforniese
Vandenberg-lugmagbasis gelanseer.

Sunsat word sedert 30 Junie 1999 oor naweke opgestel as 'n Modus B
herhaler, vir gebruik deur radio-amateurs oor die wêreld.  Ook 'n
Modus J herhaler of BHF papegaai-herhaler word by geleentheid
geskeduleer.  'n Verbeterde drywingsbegroting, weens die veranderende
sonhoek, het daartoe gelei dat herhaler-verbyvlugte onlangs uitgebrei
kon word tot weeksdae, mits ander sendingdoelwitte dit toelaat.

Uiters suksesvolle toetse van digitale dienste, wat gelyktydig aktief
kan wees, is onlangs voltooi.  Opregte dank aan WB4APR vir sy leeue-
aandeel in die toetsproses.  Besondere bydraes is gemaak deur WB3ANQ,
N7SFI, KB2WQM, KB0VBZ, N5ZNL, N4QWF, N3KTP en VK3JFK.

Benewens die analoog herhalers, sal die volgende dienste voortaan 
geskeduleer word:

*  Wanneer die wentelbaan die neem van hoëresolusie beelde toelaat,
   word die beelddata in 'n ongekonnekteerde AX.25-datastroom regoor
   die węreld uitgesaai.  Die data kan in KISS-formaat deur radio-
   amateurs versamel en via die Internet saamgevoeg word.  Dit sal
   die aflaai van die 50 MG beelde aansienlik bespoedig.  Satelliet-
   operateurs met PACSAT-stasies is welkom om by die projek aan te
   sluit.  Besoek gerus die Sunsat-tuisblad vir meer inligting:
   http://sunsat.ee.sun.ac.za/index.html.

*  Periodiese aankondigings, bulletins, statusinligting en
   gekalibreerde telemetrie word uitgesaai as ongekonnekteerde AX.25-
   pakkies, om in 'n mens-leesbare formaat deur terminaalsagteware
   vertoon te word.

*  Digi-herhaling van ongekonnekteerde AX.25-pakkies word geaktiveer.
   Dit sou onder meer gebruik kon word vir die herhaling van lae
   bandwydte APRS data.

Dié dienste sal geaktiveer word tydens alle verbyvlugte oor Dayton,
in die VSA, tydens hul jaarlikse 'Hamvention' van 19 tot 21 Mei.  Die
skedule sal gedurende die komende weke uitgebrei word tot 'n voltydse
diens, behalwe vir wanneer die analoog herhaler aktief is.

Oor Suid-Afrika word weekdag-verbyvlugte deur die Sunsat-grondstasie
benut.  Die analoog herhaler se naweekskedule gaan normaal voort. 
Een verbyvlug per naweekdag sal tipies vir beheerdoeleindes gebruik
word.  Digitale dienste sal aktief wees tydens oorblywende naweek-
verbyvlugte.  Skedules word gepubliseer op die Sunsat-tuisblad.

                                                   [ZR1CBC 19/5/2000]

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SUNSAT NOW ALSO OFFERS DIGITAL SERVICES TO RADIO AMATEURS

The Sunsat Oscar-35 micro satellite was developed at the University
of Stellenbosch, South Africa, between 1992 and 1998.  On 23 February
1999 it was launched from the Vandenberg AFB, California, by a Delta
II rocket.

Since 30 June 1999 Sunsat has provided a Mode B repeater during
weekends, for the benefit of radio amateurs across the world.  A
Mode J repeater or VHF parrot repeater is also scheduled for special
events.  An improvement in the power budget, caused by the changing
sun angle, recently led to the extension of repeater passes to
weekdays when other mission objectives permits this.

Extremely successful tests of digital services, which can be active
concurrently, were completed recently.  Sincere thanks to WB4APR for
his lion's share in the testing process.  Exceptional contributions
were made by WB3ANQ, N7SFI, KB2WQM, KB0VBZ, N5ZNL, N4QWF, N3KTP and
VK3JFK.

Apart from the voice repeaters, the following services will be 
scheduled in future:

*  When the orbit permits the acquisition of high resolution images,
   image data will be broadcast in an unconnected AX.25 data stream
   across the world.  Radio amateurs can collect data in KISS format
   and merge it via the Internet.  This process will reduce the
   download times of the 50 MB images considerably.  Satellite
   operators with PACSAT stations are invited to join this project.
   Visit Sunsat's web page, http://sunsat.ee.sun.ac.za/index.html,
   for more information.

*  Periodic announcements, bulletins, status information and
   calibrated telemetry will be transmitted as unconnected AX.25
   packets, to be displayed in human readable format by terminal
   software.

*  Digipeating of unconnected AX.25 packets will be activated.  It
   could, for example, be used for relaying low bandwidth APRS data.

These services will be enabled for all non-voice passes over Dayton,
in the USA, during their annual Hamvention from 19 to 21 May.  During
the next few weeks the schedule is to be extended to a continuous
service, except for when the voice repeater is active.

For South Africa, week-day/night passes will be used by the Sunsat
control station.  On weekends, the voice repeater will operate as at 
present.  Typically one pass per day will be used for control 
purposes.  On remaining weekend passes, digital services will be 
active.  Schedules are published on the Sunsat web page.

                                                   [ZR1CBC 19/5/2000]