A new iterated decoding algorithm is proposed for differential frequency hopping (DFH) encoder concatenated with multi-frequency shift-key (MFSK) modulator. According to the character of the frequency hopping (FH) pat...A new iterated decoding algorithm is proposed for differential frequency hopping (DFH) encoder concatenated with multi-frequency shift-key (MFSK) modulator. According to the character of the frequency hopping (FH) pattern trellis produced by DFH function, maximum a posteriori (MAP) probability theory is applied to realize the iterate decoding of it. Further, the initial conditions for the new iterate algorithm based on MAP algorithm are modified for better performance. Finally, the simulation result compared with that from traditional algorithms shows good anti-interference performance.展开更多
An innovative method of cooperative frequency domain differential modulation and demodulation is presented.This method applies the prior knowledge of channel propagation to selecting the variable differential length a...An innovative method of cooperative frequency domain differential modulation and demodulation is presented.This method applies the prior knowledge of channel propagation to selecting the variable differential length and carrying out frequency domain modulation.This strategy optimizes the design of system parameters to effectively improve the anti-interference ability of the differential system in time-varied multipath channel circumstance without making the execution more complicating.The simulations and comparisons demonstrate the proposed method is effective,and the results show that it is especially suitable for the fading channel with strong propagation and fast time-variation.展开更多
A closed form expression for the bit error rate (BER) performance of frequency domaindifferential demodulation(FDDD) for orthogonal frequency division multiplexing system in flat fadingchannel is derived.The performan...A closed form expression for the bit error rate (BER) performance of frequency domaindifferential demodulation(FDDD) for orthogonal frequency division multiplexing system in flat fadingchannel is derived.The performance is evaluated by computer simulation and compared with the timedomain differential demodulation(TDDD).The results indicate that the performance of FDDD is betterthan that of TDDD,and the lower band of BER in the former is lower than that of the latter.展开更多
The transformation between time and space is discussed. To improve real-time response speed of intelligent measuring system, the concept of exchanging program execution time with more circuitry is presented working in...The transformation between time and space is discussed. To improve real-time response speed of intelligent measuring system, the concept of exchanging program execution time with more circuitry is presented working in cycle mode. Displacement measuring by magnification is achieved with period measurement by magnification. To change the condition that traditional precision measurement depends on machining precision greatly, the concept of measuring space with time and theory of time-space coordinate transformation are proposed. Guided by the idea of measuring space with time, differential frequency measurement system and time grating displacement sensor are developed based on the proposed novel methods. And high-precision measurement is achieved without high-precision manufacture, which embeds the remarkable characteristics of low cost but high precision to the devices. Experiment and test results conform the validity of the proposed time-space concept.展开更多
The endogenous hormones (EHs) content of different explants (anther, young panicle, young embryo and mature embryo) and calli with different culture capability were analyzed by means of high performance liquid chromat...The endogenous hormones (EHs) content of different explants (anther, young panicle, young embryo and mature embryo) and calli with different culture capability were analyzed by means of high performance liquid chromatography (HPLC). The results showed that the contents and ratio of endogenous hormones were one of the key factors affecting callus induction frequencies (CIF) and green plantlet differentiation frequencies (GPDF). The influence of endogenous hormones of different explants on CIF represented as: Zoatin ribosile (ZR) showed negative effect, indole-3-acetic acid (IAA) did positive effect, and gibberellic acid (GA) did negative effect except for mature embryos. The influence of endogenous hormones on green plantlet differentiation frequency (GPDF) showed: IAA and GA were negative effect; abscisic acid (ABA) and zeatin+ zeatin riboside (Z+ZR) were positive effect. The mixture ratio of endogenous hormones played a role on CIF and GPDF. IAA/Z+ZR had a positive effect on CIF, and there was a notable positive correlation between Z+ZR/ IAA and GPDF, so was between ABA/IAA and GPDF.展开更多
文摘A new iterated decoding algorithm is proposed for differential frequency hopping (DFH) encoder concatenated with multi-frequency shift-key (MFSK) modulator. According to the character of the frequency hopping (FH) pattern trellis produced by DFH function, maximum a posteriori (MAP) probability theory is applied to realize the iterate decoding of it. Further, the initial conditions for the new iterate algorithm based on MAP algorithm are modified for better performance. Finally, the simulation result compared with that from traditional algorithms shows good anti-interference performance.
基金supported by the National Basic Research Program of China (973 Program) (2007CB310605)
文摘An innovative method of cooperative frequency domain differential modulation and demodulation is presented.This method applies the prior knowledge of channel propagation to selecting the variable differential length and carrying out frequency domain modulation.This strategy optimizes the design of system parameters to effectively improve the anti-interference ability of the differential system in time-varied multipath channel circumstance without making the execution more complicating.The simulations and comparisons demonstrate the proposed method is effective,and the results show that it is especially suitable for the fading channel with strong propagation and fast time-variation.
基金Supported by National Natural Science Foundation of China(No.60272009)and National 863 Plan Project(NO.2001AA1230131)
文摘A closed form expression for the bit error rate (BER) performance of frequency domaindifferential demodulation(FDDD) for orthogonal frequency division multiplexing system in flat fadingchannel is derived.The performance is evaluated by computer simulation and compared with the timedomain differential demodulation(TDDD).The results indicate that the performance of FDDD is betterthan that of TDDD,and the lower band of BER in the former is lower than that of the latter.
基金National Natural Science Foundation of China(No.59575095,No.59675089,No.50075091,No.50575235)
文摘The transformation between time and space is discussed. To improve real-time response speed of intelligent measuring system, the concept of exchanging program execution time with more circuitry is presented working in cycle mode. Displacement measuring by magnification is achieved with period measurement by magnification. To change the condition that traditional precision measurement depends on machining precision greatly, the concept of measuring space with time and theory of time-space coordinate transformation are proposed. Guided by the idea of measuring space with time, differential frequency measurement system and time grating displacement sensor are developed based on the proposed novel methods. And high-precision measurement is achieved without high-precision manufacture, which embeds the remarkable characteristics of low cost but high precision to the devices. Experiment and test results conform the validity of the proposed time-space concept.
文摘The endogenous hormones (EHs) content of different explants (anther, young panicle, young embryo and mature embryo) and calli with different culture capability were analyzed by means of high performance liquid chromatography (HPLC). The results showed that the contents and ratio of endogenous hormones were one of the key factors affecting callus induction frequencies (CIF) and green plantlet differentiation frequencies (GPDF). The influence of endogenous hormones of different explants on CIF represented as: Zoatin ribosile (ZR) showed negative effect, indole-3-acetic acid (IAA) did positive effect, and gibberellic acid (GA) did negative effect except for mature embryos. The influence of endogenous hormones on green plantlet differentiation frequency (GPDF) showed: IAA and GA were negative effect; abscisic acid (ABA) and zeatin+ zeatin riboside (Z+ZR) were positive effect. The mixture ratio of endogenous hormones played a role on CIF and GPDF. IAA/Z+ZR had a positive effect on CIF, and there was a notable positive correlation between Z+ZR/ IAA and GPDF, so was between ABA/IAA and GPDF.
