A 300 km link between your payload and you
To allow an error free communication channel between the satellite and ground station, we use the concatenated code (7,1/2). This coding scheme is still used in NASAs Deep Space Network to communicate with Voyager 1, which is 149 AU (Earth-Sun distance) away from Earth. (2020)
More information: Butman 1981: Performance of concatenated codes for deep space missions
We chose a carrier frequency of 868 MHz (UHF), which equals a wavelenght of 34.53 cm wavelength.
Our self-developed radio module has a maximum TX power of 100 mW (20 dBm). The components in the signal path are carefully chosen to have a minimum signal loss.
Because eSat will be deployed in LEO (Low earth orbit), we do not need the big 30m radio antennas like used in the Deep Space Network. For communicating with eSat, a handheld 13dBi yagi antenna, which is included in our kit, is sufficient.
Because eSatv2 does not have pointing capabilities, we have to use a simple antenna dipole, to be able to communicate with the satellite from all directions. To store and deploy the antenna safely in space, we use a custom formed antenna made out of a shape-memory alloy. This special metal will be freely deformable when cold to store, but will change to its desired shape when heated by the sun in space.
We tested the hysteresis memory effect with a heart-shaped wire, as visible in the picture.
