Software Measurement And Control The Answering Machine Of A Preliminary Study

Miniature satellite is one of the most important research fields in the modern aeronautic technology. Formation flying miniature satellites are composed of many miniature satellites, which fly in a fixed formation and finish the complicated aeronautic tasks by their cooperation. There are two kinds of problems related to the formation flying miniature satellites. One is to measure and control the satellite track from the ground, and the other is to decide the relative position of the miniature satellite in the formation. How to implement these two functions under the condition of limited volume and power is one of the problems to be considered. Software defined radio is an efficient solution to this question.Software defined radio is a new developed technology due to the development of the microelectronics field in recent several years. The traditional realization way of the radio is focused on the hardware and purposed on some specific application. However, software defined radio employs the software on a hardware platform to realize the tasks of the radio.The technology of software define radio could be applied in the TT&C transponder. After careful design, the transponder carrying the system to track the ground carriers could have the same hardware structure as the one using PN codes to measure the distance between two satellites. The change of its software could realize these two functions. Therefore, formation flying miniature satellites only need to have such a transponder, and run different software if necessary to realize the functions of the above two transponders respectively.The overview of this paper is shown as follows:1, Analyze two different modulation schemes: the demodulation principles of thephase- modulated signal and the BPSK-modulated signal, analyze the differencebetween them, and present a general hardware platform. This hardware includes theanalog part and the digital part. The analog part is composed of RF receiver andtransmitter.2n In the signal receiving part, coherent carrier extraction is predominant; In the transmission part, there is carrier tracking transmission to estimate the speed. In this paper, we employ the structure of the embedded nested loops, which are made up of carrier tracking loop and phase-locked frequency synthesizer, and could do the carrier tracking and recovery. Then, we could extract the carrier coherent to the received signal to change the frequency and mix the frequency. This paper present the way to extract the carriers of PM signal and BPSK signal, respectively.3 % This paper utilizes the idea of software defined radio. The baseband processing is finished in the digital circuit part, including the phase-locked loop filter, the distance-measuring signal splitter and tranpond, etc. Employing the digital circuit to do the baseband part could improve the flexibility of the system. Different signals could be received by different loop filters and baseband correlators, which makes one platform receive, lock and demodulate different signals.4- Signal modulation employs zero-IF (intermediate frequency) modulation scheme, which could simplify the system structure and lower the consuming power. Meantime, using the I/Q modulated chip, we could control the signal inputted to the chip by the baseband processing part, then adjust the output signal form.