针对月面着陆信标辅助导航中存在的信标位置不确定问题,提出了一种基于稀疏扩展混合滤波(SEHF)的信标辅助导航方法。首先采用稀疏扩展信息滤波(SEIF)进行量测更新过程,实现对着陆器当前位置、速度及月面信标位置的联合估计。在此基础上...针对月面着陆信标辅助导航中存在的信标位置不确定问题,提出了一种基于稀疏扩展混合滤波(SEHF)的信标辅助导航方法。首先采用稀疏扩展信息滤波(SEIF)进行量测更新过程,实现对着陆器当前位置、速度及月面信标位置的联合估计。在此基础上,进一步采用"均值矢量+信息矩阵"的混合形式进行状态预测过程,以提高算法在异步量测下的计算效率。仿真结果表明,所提出方法的收敛速度和估计精度均优于传统扩展卡尔曼滤波(EKF),且相较于原始SEIF可缩短16%左右的计算耗时;此外,当信标位置存在150 m (1σ)初始误差时,所提出方法的着陆点位置估计优于50 m (CEP)。展开更多
High efficiency audio compression is the basic technology in audio involved multimedia communications. Downmixing and parametric coding is efficient coding scheme with wide applications in some up-to-date audio codecs...High efficiency audio compression is the basic technology in audio involved multimedia communications. Downmixing and parametric coding is efficient coding scheme with wide applications in some up-to-date audio codecs such as Parametric Stereo (PS) in EAAC+ and MPEG-Surround. Principle Component Analysis (PCA) stereo coding followed this idea to map two channels to one channel with maximum energy and parameterize the secondary channel. This paper investigates the conventional PCA method performance under general stereo model with multiple sound sources and different directions, and then proposes a Polar Coordinate based PCA (PC-PCA) stereo coding method. It has been proved that when multiple sound sources exist with different directions, PC-PCA is better than the conventional PCA method when Mean to Standard deviation Ratio (MSR) is large. A stereo codec based on PC-PCA is proposed to validate the performance improvement of proposed method. Objective and subjective tests show the proposed method achieves a comparative quality and saves 50% parameter bit rate comparing with conventional PCA method, and obtains a 4-8 MUSHRA scores improvement comparing with state-of-the-art stereo codec at the same parameter bit rate.展开更多
In this paper, a low-cost dualtone radio interferometric positioning system using a single mobile anchor is proposed to locate multiple targets at the same time. We name it mDRIPS. In mDRIPS, each target continuously ...In this paper, a low-cost dualtone radio interferometric positioning system using a single mobile anchor is proposed to locate multiple targets at the same time. We name it mDRIPS. In mDRIPS, each target continuously transmits a dual-tone signal with its dedicated frequencies, and the mobile anchor receives the signals at different positions along its trajectory, Neither time synchronization between the mobile anchor and the targets nor time synchronization among the targets is required. We take the instability of targets clocks into consideration and develop an ESPRIT-type algorithm to estimate frequencies of each dual-tone signal. Furthermore, the time of arrival （TOA） of each target signal is extracted from the phase estimates of the received dual-tone signals. After measuring several TOAs at different locations along the anchor＇s trajectory, each target can be located. Since the frequency difference of the two tones of each dualtone signal is designed to be smaller than the channel coherence bandwidth, the same fading effect on these two tones can be eliminated. Moreover, the integer ambiguity problem due to phase wrapping is investigated, and a localization algorithm to deal with a simplified ambiguity problem is proposed. Numerical results demonstrate the efficiency of the proposed mDRIPS.展开更多
文摘针对月面着陆信标辅助导航中存在的信标位置不确定问题,提出了一种基于稀疏扩展混合滤波(SEHF)的信标辅助导航方法。首先采用稀疏扩展信息滤波(SEIF)进行量测更新过程,实现对着陆器当前位置、速度及月面信标位置的联合估计。在此基础上,进一步采用"均值矢量+信息矩阵"的混合形式进行状态预测过程,以提高算法在异步量测下的计算效率。仿真结果表明,所提出方法的收敛速度和估计精度均优于传统扩展卡尔曼滤波(EKF),且相较于原始SEIF可缩短16%左右的计算耗时;此外,当信标位置存在150 m (1σ)初始误差时,所提出方法的着陆点位置估计优于50 m (CEP)。
基金supported by National Natural Science Foundation of China under Grants No. 61231015, No. 61102127 No. 61201340, No. 61201169Major National Science and Technology Special Projects under Grant No. 2010ZX03004-003-03+2 种基金Natural Science Foundation of Hubei Province under Grant No. 2011CDB451Wuhan ChenGuang Science and Technology Plan under Grant No. 201150431104the Fundamental Research Funds for the Central Universities
文摘High efficiency audio compression is the basic technology in audio involved multimedia communications. Downmixing and parametric coding is efficient coding scheme with wide applications in some up-to-date audio codecs such as Parametric Stereo (PS) in EAAC+ and MPEG-Surround. Principle Component Analysis (PCA) stereo coding followed this idea to map two channels to one channel with maximum energy and parameterize the secondary channel. This paper investigates the conventional PCA method performance under general stereo model with multiple sound sources and different directions, and then proposes a Polar Coordinate based PCA (PC-PCA) stereo coding method. It has been proved that when multiple sound sources exist with different directions, PC-PCA is better than the conventional PCA method when Mean to Standard deviation Ratio (MSR) is large. A stereo codec based on PC-PCA is proposed to validate the performance improvement of proposed method. Objective and subjective tests show the proposed method achieves a comparative quality and saves 50% parameter bit rate comparing with conventional PCA method, and obtains a 4-8 MUSHRA scores improvement comparing with state-of-the-art stereo codec at the same parameter bit rate.
基金partially supported by the National Nature Science Foundation of China under Grants 61301223,61174127,61221003, and 61273181the Nature Science Foundation of Shanghai under Grant 13ZR1421800the New Faculty Foundation of Ministry of Education of China under Grant 13Z102090106
文摘In this paper, a low-cost dualtone radio interferometric positioning system using a single mobile anchor is proposed to locate multiple targets at the same time. We name it mDRIPS. In mDRIPS, each target continuously transmits a dual-tone signal with its dedicated frequencies, and the mobile anchor receives the signals at different positions along its trajectory, Neither time synchronization between the mobile anchor and the targets nor time synchronization among the targets is required. We take the instability of targets clocks into consideration and develop an ESPRIT-type algorithm to estimate frequencies of each dual-tone signal. Furthermore, the time of arrival （TOA） of each target signal is extracted from the phase estimates of the received dual-tone signals. After measuring several TOAs at different locations along the anchor＇s trajectory, each target can be located. Since the frequency difference of the two tones of each dualtone signal is designed to be smaller than the channel coherence bandwidth, the same fading effect on these two tones can be eliminated. Moreover, the integer ambiguity problem due to phase wrapping is investigated, and a localization algorithm to deal with a simplified ambiguity problem is proposed. Numerical results demonstrate the efficiency of the proposed mDRIPS.
