(Manned Amateur Radio Experiment, North American Division)
Slow Scan Television
International Space Station
Amateur Radio Project
G. Miles Mann WF1F
Web version March 8, 2001
The MAREX-MG SPACECAM-1 System is an entry-level PC based Slow Scan Television system designed to be used on board the International Space Station. The SPACECAM-1 system will support multiple common SSTV transmission modes. And has been specifically designed to be accessible to as many stations as possible around the world. The original proof-of-concept system was built by the MAREX-MG team and successfully flown on the Russian Space Station Mir (December 1998 till present). The proof-of-concept system has proven the ability of the hardware design and it has taught us how to make additional improvements for the next generation SSTV system for ISS.
The MIREX/MAREX-MG team had over 9 years of experience in continuous support of Manned Amateur Radio Space Flight projects. This experience has prove over and over again in our ability to anticipate potential problems and to make corrections to avoid problems.
With minimal assistance and support from the amateur radio community and sponsors it should be possible for MAREX-MG to deliver flight quality software and hardware to Russia for safety testing in Q2 2001.
This project will satisfy some of the project requirements requested by Energia's Chief of Cosmonaut Amateur Radio Department Sergej Samburov in their fax proposals in June 1998. The original project request from Energia had a specific request for a Slow Scan TV project.
The MAREX-MG SPACECAM-1 uses a very common mode of image transmission format, which is commonly used on HF and VHF frequencies. SSTV has already been used through several Amateur Radio satellites, including the Space Shuttle and the Russian Space Station Mir. The FM transmission mode has proven to be easy to use and helps reduce interference and will allow easier Doppler frequency tracking.
External Antenna Connections:
The MAREX-MG ISS SPACECAM-1 system will need to be connected to one of the existing 5 Amateur Radio external antenna ports on ISS. The preferred operational amateur radio band would be the 2-meter band. The MAREX-MG ISS SPACECAM-1 system will be capable of operating on either the 2-meter or 70 centimeter bands. The frequency flexibility of the system is a desirable feature. The feature will allow the ISS HAM Technical team great flexibility in choosing frequencies. The actual frequency and band can be changed while in flight.
The MAREX-MG SPACECAM-1 system will need to be connected to 12-14 VDC power source. At the present time, the MAREX-MG team has been informed by Energia/MAREX-RU, that the 28 VDC power converters will be provide by a commercial power supply company.
The ISS SPACECAM-1 project development is well under way. Existing PC-SSTV software is being modified specifically for the SPACECAM-1 Project. The software chosen has been on the public market for over a year and has proven to be very stable. Specific modifications are being made to make the SPACECAM-1 system easier to use. Sponsors for the ISS SPACECAM-1 project have been contacted and was are negotiation additional hardware for the ISS SPACECAM-1 project. The first beta release of the SPACECAM-1 software has already been delivered to ARISS and MAREX-RU.
System Control Tabs
When placed into manual mode, the SPACECAM-1 system will stay in this mode until the ISS crew manually makes a change or the SPACECAM-1 system receives a Sysop DTMF command.
When placed into BEACON mode, the SPACECAM-1 system will stay in this mode until the number or beacons transmission has completed. After the beacons have completed, the SPACECAM-1 system will switch to Slide Show mode
REPEATER MODE (a few variations here)
When activated, the SpaceCam system will automatically repeat the image it just received. This will enable users to send an image from earth to ISS and have it rebroadcast over a 1500 mile radius.
SLIDE SHOW (camera or disk)
When placed into Slid Show mode, the SPACECAM-1 system will repeat every image in the directory for the number of loops requested.
The computer being used on ISS is an IBM-760XD, running Window-95 OS. This computer has a built-in RS-170 composite video input and output connection (just like a VCR). This connection will allow the ISS crew to connect any standard video device, (camcorder, Digital Camera, etc) directly to the PC. The live video images can then be selected as a video source for SpaceCam1
The above sequence repeats every 74 seconds, automatically acquiring a new picture every transmission. For example, if camera was pointed to Earth, a different image would be acquired and Transmitted each time. If camera is viewing inside of spacecraft, then unless camera is moved or the inside scene changes, the same picture keeps repeating. In Slide-Show mode, SpaceCam1 will send every image from the selected disk directly and then repeat the process over again for a pre selected number of loops.
The SpaceCam-1 System will listen to the radio channel for a 1750 HZ frequency tone. If the tone is heard, the SpaceCam-1 system will transmit the letter "K" in Morse code to tell the Earth station the SpaceCam-1 system is ready for receive a new SSTV image. After a successful reception of an SSTV image from Earth the SpaceCam-1 system will then send the image back to Earth for everyone to see, in Robot 36 mode of transmission.
The SpaceCam1 system is designed to read many of the common image storage format including GIF, JPG etc. This will allow the crew to use their own digital cameras to to take pictures and save these images on the SpaceCam1 PC and send these images back to earth later via SSTV.
When Audio Save is enabled, all new images received by Spacecam1 will be saved to the PC disk drive. Each image will automatically be saved in a directory on the PC. Each image will have a unique name which will include the date and time. Spacecam1 will also track the number if images stored in the "Default Image" directory. The ISS crew can set a maximum image counter which will tell SpaceCam1 when to start deleting old images to help save disk space.
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