TUMnanoSAT communication module is designed to operate in the amateur frequency band 430 to 440 MHz (Tx/Rx). The modulation used is GMSK, at a rate of 9600 bps. The diagram of communication subsystem is presented below.
By default, the transceiver works in half-duplex mode with configurable data rate and modulation index (m). It has the option to transmit a beacon signal with predefined information.
The UHF Antenna module is designed to cover the amateur satellite band 435-438 MHz. The antenna is circularly polarized, and uses a burn wire mechanism with feedback for the deployment of the antenna rods. The module has an internal microcontroller to control and monitor the release of the antenna rods. Communication to the module is via an I2C interface.
The module uses a triple redundant system to ensure deployment of the antenna rods. The burn wire mechanism has double redundancy. In addition, the microcontroller can be bypassed to control the burn resistors directly via general purpose inputs on the module interface.
Antenna pattern of antenna in free space is presented in the next figure
The link budget for TUMnanoSAT can be accessed through the following link: Up-Down link Communication TUMnanoSAT: