Launch of EASAT-2 and HADES satellites
The camera chip is the Omnivision OV2640, which provides a resolution of up to 2M pixels and compressed output in JPEG. Resolution is limited by the CPU’s internal memory (MCU) that controls the camera to 320×240 (typical) or 640×480 maximum. The MCU selected for the control is the STM32F446RET6, which has the smallest possible footprint with connection to DCMI peripheral, necessary for connection with the camera.
Images can be stored on a 2 MB serial flash memory. The complete SSTV encoder has managed to be implemented in a 4-layer PCB with dimensions of only 38x38mm.
The MCU can be fully controlled from ground stations. The firmware allows the sending of images of the camera live,of imágenes previously saved in the flash memory or of images encoded in ROM. It also provides advance programming of image acquisition and PSK telemetry with the current status (event counters, temperature, voltage, light conditions, etc.) and a brief summary.
The described module has been developed and manufactured at the Department of Radioelectronics of the Brno University of Technology in the Czech Republic. Both hardware and firmware designs with the source codes will be available on Github under the MIT license (https://github.com/alpov/SatCam).
Initially only the EASAT-2 repeater is active. Hades’ will be activated by telecommand a few days after launch.
The frequencies coordinated with IARU for both satellites are as follows:
- 145.875 MHz uplink, Modes: VOICE FM (without undertone) and FSK 50 bps, AFSK, AX.25, APRS 1200 / 2400 bps
- 436.666 MHz downlink, Modes: FM voice, CW, FSK 50 bps, FM voice beacon with AM5SAT callsign
- 145.925 MHz uplink, Modes: VOICE FM (without undertone) and FSK 50 bps, AFSK, AX.25, APRS 1200 / 2400 bps
- 436.888 MHz downlink, Modes: FM voice, CW FSK 50 bps, SSTV Robot 36, FM voice beacon with AM6SAT callsign
The description of the transmissions can be found in the following document:
AMSAT-EA appreciates the reception of telemetry, voice beacons and SSTV images. A paper QSL is sent to those who send their transmissions. It can be done through the following link: http://data.amsat-ea.org
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