# Конструктор спутника "ОрбиКрафт"

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VHF transmitter
Virtual consumption - 210mA

The spacecraft telemetry transmitter is most often a VHF transmitter operating at either the 145 or 436 MHz range and providing a low data rate with an omnidirectional or near-omnidirectional on-board antenna. A high data rate is not needed here as the amount of telemetry information from the device is usually much lower than the data rate from the payload for which this satellite was launched into space. Additionally, if there are problems on-board and if the device loses its orientation, this communication channel will remain available in order to obtain critical information about the state of the on-board service systems and restore the satellite's operability.

In case of board abnormalities, any and all information is extremely important. The information allows the operational control group that is on duty at the MCC and working with the satellite in communication sessions to identify problems and decide how to solve those problems. In this case, the low-speed communication channel consumes a small amount of energy in comparison with the HF radio channel.

As part of the construction set, the VHF radio channel is implemented in the form of two modules: the on-board transmitter module and the ground receiver module. Data transfer to the ground is carried out using the following function:

int32_t transceiver_send(uint16_t tx_num,uint16_t rx_num,const uint8_t *data,uint16_t len);

Under the experimental conditions the transmitter has the number “2” (marked on the body), and the receiver (ground) is number “1”. The array of data transmitted from the board to the Earth is a byte array of arbitrary length and composition that can be transmitted to the Earth, indicating its length. On Earth, messages received during a communication session are displayed in real time in the MCC software interface “as is,” so it is most advantageous to transmit telemetry in text form.