The effect of IF (intermediate frequency) analog AGC on QPSK/OQPSK signal detection is evaluated for LEO satellite system where Doppler drift, large dynamic range of signal power and low Eb/No condition are difficult ...
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The effect of IF (intermediate frequency) analog AGC on QPSK/OQPSK signal detection is evaluated for LEO satellite system where Doppler drift, large dynamic range of signal power and low Eb/No condition are difficult to deal with. The way of setting reference value of logarithmic power based AGC is discussed. Coherent accumulation and non-coherent accumulation are used for detecting, while signal's PDF and performance vs. accumulation times are derived mathematically. Experiment shows that with 60 KHz Doppler offset, Eb/No=0dB under QPSK/OQPSK, only 16 bits was consumed to detect the signal with 99.9% detection probability and 0.1% false alarm probability.
Silicon solid-state small satellite (or nano satellite) is a new kind of aerospace aircraft, which adopts ideas greatly different from the conventional method. The small satellite is composed of ASIMs, which make the ...
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Silicon solid-state small satellite (or nano satellite) is a new kind of aerospace aircraft, which adopts ideas greatly different from the conventional method. The small satellite is composed of ASIMs, which make the conventional complex system into a single system with IC and MEMS technologies. The fundamental principle of how to improve the silicon-solid state small satellite is discussed, as well as its application in special data store and forward communication. We also introduce our research on MEMS application in space. A practical design of a data communication nano satellite about 15 kG in weight and 10 inch in line length is also given.
Time-encoded imaging could be useful for searching potential radioactive sources for preventing illicit trans-portation and trafficking of nuclear materials. A 2-D, dual-particle, time-encoded imager was developed for...
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Time-encoded imaging could be useful for searching potential radioactive sources for preventing illicit trans-portation and trafficking of nuclear materials. A 2-D, dual-particle, time-encoded imager was developed for gamma-ray and neutron source imaging. The influence of central detector and coded mask rotation speed to imaging performance, such as angular resolution, signal-to-noise ratio and detection time, was investigated by Am-Be neutron source imaging experiments. The EJ276 plastic scintillator (Size: phi 5.08 cm x 5.08 cm) and CLYC scintillator (Size: phi 2.54 cm x 2.54 cm) couple to photomultiplier tubes was set as the central detector, respectively. Under the experiment conditions (Am-Be neutron source;300 mCi;1.8 m), for the neutron and gamma-ray images with EJ276 detector, the best horizontal and vertical angular resolution was (3.7 degrees, 4.8 degrees) and (5.9 degrees, 6.6 degrees), minimum detection time was 100 s and 600 s, respectively;for the neutron and gamma-ray images with CLYC detector, the best horizontal, vertical angular resolution was (3.1 degrees, 3.1 degrees) and (3.5 degrees, 3.3 degrees), minimum detection time was 2200 s and 1600 s, respectively. For different central detector, the results showed that the smaller volume of detector, the better angular resolution;the lower detection efficiency, the longer detection time. For different rotation speed, too fast rotation speed can lead to failure to locate the source.
Silicon solid-state small satellite(or nano satellite) is a new kind of aerospace aircraft,which adopt ideas greatly different from the conventional *** small satellite is composed of ASIMs, which make the conventiona...
详细信息
Silicon solid-state small satellite(or nano satellite) is a new kind of aerospace aircraft,which adopt ideas greatly different from the conventional *** small satellite is composed of ASIMs, which make the conventional complex system into a single system with IC and micro electronic mechanical system(MEMS) *** fundamental principle of how to improve silicon-solid state small satellite in China is discussed here,as well as its application in special data store and forward *** also introduce our research of MEMS and its application in space.A practical design of data communication nano satellite about 15KG in weight and 10 inch in line length is also given out.
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