Study on a high performance and multifunictional software receiver for plasma wave instrument

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We studied optimal algorithms for a software receiver onboard scientific satellite. For the purpose of designing optimal onboard software which obtains the maximum scientific output of the plasma physics, we examined several algorithms for data selection and data compression as well as signal processing for spectral analysis to be performed on a plasma wave instrument onboard the satellite. The main conclusions are summarized as follows:1. In order to obtain spectral data from wideband waveform capture using software installed on an onboard CPU, we proposed an optimal analyses method, especially for very low frequency range with a high frequency resolution.2. Data compression algorithm is also important to achieve higher data compression ratio as well as to keep fine data quality for scientific objectives. Both lossless and lossy algorithms are taken into account for the spectrum data. We demonstrated that higher data quality can be obtained by JPEG applying to higher time resolution data than by adaptive range-coder applying to nominal resolution data. As for the waveform data, we proposed a new sub-band ceding method.3. Onboard software processing was simulated using a small CPU, which is compatible to the one used for a scientific satellite. We measure execution times for the proposed data processing methods, and showed optimal parameters for the data processing.4. Automatic data detection and estimation of the dispersion characteristics of the lightning whistlers was developed. We demonstrated that the proposed method is applicable for the data selection for lightning whistlers, and the derived dispersion properties are useful for the reconstruction of a spatial profile of electron density in the plasma sphere.