 UoSAT-OSCAR 22
(UoSat 5)
Spacecraft Summary
| OSCAR Designation: |
UoSAT-OSCAR 22 |
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Oscar Number: |
UO-22 |
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| International Designator: |
1991-050B |
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Norad Number: |
21575 |
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| Common Name: |
UoSat 5 |
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Satellite Type: |
Microsatellite |
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| Launch Date: |
17 July, 1991 |
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Launch Location: |
French Guiana |
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| Launch Vehicle: |
Ariane 4 |
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Apogee: |
766.00 |
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| Perigee: |
754.00 |
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Inclination: |
98.28 |
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| Period: |
100.03 |
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Weight: |
0.000 Kg |
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| Organization: | University of Surrey |
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Frequency Information
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| Mode V/U (J) PacSat BBS: Non-Operational |
| Uplink: |
145.9000 MHz FSK 9600 BPS |
| Downlink |
435.1200 MHz FSK 9600 BPS |
| Callsign(s)| Broadcast: | UOSAT5-11 | | BBS: | UOSAT5-12 |
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Current Keplerian Elements
UO-22
1 21575U 91050B 09325.53132574 .00000020 00000-0 20397-4 0 6943
2 21575 98.4677 272.3852 0006512 268.4166 91.6276 14.39692011963341
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Detailed Description
UoSAT-OSCAR-22 is in a series of Amateur Radio communications satellites designed and built by the Department of Electrical Engineering at the University of Surrey in Guildford, Surrey, England.
UoSAT-OSCAR-22 was launched on July 17, 1991 on an Ariane rocket along with four "microsatellites", one of which is an amateur astronomy satellite called "SARA". UoSAT-OSCAR-22 is a multiple mission spacecraft designed to serve several audiences. One mission was to carry out experiments originally slated for UoSAT-OSCAR-15, whose on-board electronics failed shortly after the spacecraft reached Earth orbit. The primary purpose of UoSAT-OSCAR-22, however, was to provide non-amateur radio related store-and-forward digital communications for VITA and SatelLife, a non-profit, humanitarian organization.
UoSAT-OSCAR-22's primary role in space was later modified when the satellite played a part in Amateur Radio's first "role reversal" with another spacecraft, UoSAT-OSCAR-14. One of the most unique aspects of UoSAT-OSCAR-22 is its Earth Imaging System (EIS), designed by University of Surrey doctoral student Marc Fouquet. The Earth System was designed to capture Earth images from low-Earth orbit using a charge coupled device (CCD) camera, and broadcast those images to ground stations using amateur frequencies and the AX.25 packet radio "Pacsat Broadcast Protocol" when the spacecraft was not providing service to SatelLife.
The monochrome CCD imager produces a CCIR video image having a resolution of 578x576 pixels with an aspect ratio of 4:3. Images taken by the CCD camera are first digitized using an 8-bit half-flash analog to digital converter, and then stored in RAM for later processing and transmission over the downlink transmitter. Received images can be captured and displayed using a personal computer with suitable graphics capability. The images can also be converted to popular GIF and JPEG formats and viewed in those forms if so desired.
The Big Switch
While UoSAT-OSCAR-22 was serving the needs of SatelLife, UoSAT-OSCAR-14 was providing the Amateur Radio Service with its only 9600 baud packet radio store-and-forward communications satellite. In late December 1991, UoSAT spacecraft controllers introduced an enhanced broadcast server on UoSAT-OSCAR-14 which did a lot to reduce congestion on the satellite's single uplink frequency. However, since OSCAR-14 had only 256 kilobytes of memory, the spacecraft used a RAMDISK system which could only store 400 packet messages at a time. With uplink contention reduced, packet gateways on line, and more than 150 stations regularly active on OSCAR-14, the 400 message limit was often exceeded. When the satellite message space became full, new messages could not be uploaded and older messages had short lifetimes before being deleted automatically to make way for new messages.
After some initial use, it became clear that OSCAR-22's CCD imager success and the less than optimum conditions on OSCAR-14 required that some operating changes to both UoSAT-OSCAR-14 and UoSAT-OSCAR-22 be made. Amateur stations around the world were downloading CCD Earth images several times per week, with each image containing more than 300 kilobytes of data. Furthermore, it was discovered that OSCAR-22's high power amplifier which produced excellent output on amateur frequencies, did not work reliably on the non-amateur frequencies used by SatelLife operations.
Taking into account the resources available and the obligations to SatelLife, HealthNet and VITA, UoSAT controllers decided to swap the roles of UoSAT-OSCAR-14 and UoSAT-OSCAR-22 in a attempt to optimize the capabilities and resources of each spacecraft. On February 5, 1992, all non-amateur traffic, both SatelLife and VITA, moved from OSCAR-22 to OSCAR-14, which no longer transmitted on its amateur downlink frequency. All amateur traffic moved from OSCAR-14 to OSCAR-22, and OSCAR-22 then operated as a dedicated amateur radio satellite transmitting constantly on its amateur downlink frequency.
UO-22 Ground Station Requirements
Hardware requirements for full access to OSCAR-22 include a 9600 baud packet radio modem, a pair of low-gain directional antennas for the satellite's Mode JD link frequencies, a 2-Meter FM uplink transmitter, and a 70-cm FM downlink receiver. Pacsat terminal software such as PB, PG, PHS, and PFHADD are used with OSCAR-22 just as they are with PACSAT-OSCAR-16 and LUSAT-OSCAR-19. Programs such as these, along with a KISS mode capable TNC allow ground stations to access the mailbox and file server available on the satellite, as well as capture CCD imager data from the spacecraft. Both text and executable binary files may be downloaded from the satellite or fed into a queue for broadcast to all stations within the footprint of the satellite using the Pacsat broadcast protocol. Pacsat terminal software is widely available for MS-DOS compatible computers as "freeware" on many dial-up BBS systems that carry Amateur Radio related software. UoSAT-OSCAR-22 is currently the only 9600 baud store-and-forward packet radio satellite available for amateur radio use.
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Reference Documents:
- Jeff Ward, "UoSAT Oscar 22 in Orbit," QST, Sep 1991, p. 70.
- Jeff Ward, "The UO-22 Earth Imaging System," The AMSAT Journal, Vol. 14, No. 6, Nov/Dec 1991, p. 1.
- John A. Magliacane, " Spotlight On: UoSAT-OSCAR-22," The AMSAT Journal, Vol. 15, No. 3, May/Jun 1992, p. 17.
- Daniel, Walter, KE3HP, "Computer Processing of UO-22 and KO-23 Images," The AMSAT Journal, Vol. 16, No. 1, Jan/Feb 1993, pp. 8-10.
- Mike Crisler, PACSAT Beginner's Guide, AMSAT.
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