- Author: Mugdadi Mu’ayyad
The work presented in this thesis is dedicated to the development of a remote sensor for HUMSAT which is a development of a nano-satellite constellation .
The HUMSAT system architecture is composed of three segments ; space segment , ground segment , and user segment . the user segment formed by the sensors freely deployed and developed by users and by the facilities that users shall design and construct by their own in order to retrieve and send the data.
Data transmission between sensors and the satellite could be Non-bi-directional , bi-directional and full-bi-directional , this thesis describes the non-bi-directional data transmission so a single sensor transmits continuously the frames that it has generated previously until a spacecraft collects them .
A temperature sensor (NTC thermistor ) has been created in order to take part of the user segment , for this goal it has been designed an electronic circuit and its’ PCB , using mentor circuit designer , the circuit is built of a temperature sensor which is connected with a microcontroller ( MSP430F5438 ) and a transceiver ( Si4464 ) , the sensor will relieve the temperature every a defined period and send it to the microcontroller , the microcontroller will recognize if this temperature is in a certain defined range , if the temperature is out of the range the microcontroller will communicate the transceiver to send the data packet .
Some specifics has to be taken into consideration for the data transmission , frequency band is 401-402 MHz , GMSK modulation , EIR is about +27 dBm , for these specifics the Si4464 transceiver has been chosen , the output power of the transceiver was not sufficient , in order to increase the output power of the transceiver a power amplifier is implemented .
Two RF switches is implemented to isolate the transmission and reception chains .
For low power consumption , it is thought to deactivate the transceiver and the PA when it is not necessary to be active , like while the microcontroller is still reading temperature from the sensor , and if the temperature is in the range defined .
In order to configure the microcontroller , the transceiver , and generally reading and transmitting data , C programming codes is written in IAR Embedded workbench .
- Year: 2013
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