太阳系天体地面VLBI观测的相对论时延模型

以太阳系质心参考系为基础，根据太阳系的质心参考系和非旋转地球质心参考系的坐标转换关系，推导了太阳系天体地面VLBI观测的相对论时间延迟模型，给出了一个通用的解析表达式．根据这一公式可以得到平劲松博士所采用的公式，以及当地心与源的距离无限大时，可得河外射电源VLBI观测的Zhu—Groten模型、Shapiro模型和IERS(92，96)推荐模型．所推导的公式严格解析且无误差，在实际应用中建议采用这一公式．同时详细地讨论了所推导公式的实用范围和各种舍掉项的量级估计，并详细给出了时间延迟理论模型的计算步骤．     

Degradation due to Quantization Noise in Radio Astronomy Phased Arrays

In this article, a model is developed for determining the probability distribution of the output of a digital adder in case of 2-, 3- and 4-level quantization before summation. This probability distribution is then used to determine the efficiency of a system which determines the total power of the signal at the output of the digital adder.The sum-signal is also used in a VLBI correlation mode where the sum-signal is correlated with the signal from a VLBI partner. The efficiency, expressed in so-called Degradation Factors, is determined for 1- and 2-bit correlation and 2-, 3- and 4-level quantization before summation.Furthermore, the application of the calculated values (Total Power Detector Efficiencies and Degradation Factors) is illustrated.     

利用DiFX处理CVN天文观测数据进展

相关处理机是VLBI观测数据处理的核心单元,相关处理机的输出结果可以直接作为天文成图、测地学以及航天器干涉测量等应用的输入。DiFX是运行在分布式计算、共享存储单元的集群环境下最成功的软件相关处理机之一。首先介绍上海天文台DiFX综合平台的现状;然后介绍利用DiFX相关处理机处理中国VLBI网(CVN)天文观测数据的进展:最后简短展望了DiFX平台为CVN及国际VLBI天文观测提供相关处理服务的前景。可为利用该平台的相关处理结果开展科学研究提供参考。     

VLBI监控系统的改进

对Mark5B监控系统软件的设计思想、软件功能、通讯机制等几个方面作了介绍。Mark5B记录系统是当今世界VLBI观测台站中广泛使用的最为先进的记录系统之一,也是VLBI终端系统的重要组成部分。研制Mark5B监控系统软件的主要目的是进一步提高VLBI终端记录系统的可靠性,保障VLBI联测数据有效和高质量。该软件是在Qt开发环境下采用signals/slots的安全类型机制,并在Qt creator IDE上设计图形界面,完成数据采集和网络通信工作。Mark5B监控系统不仅适用于VLBI天体物理测量观测、VLBI测地观测,而且适用于中国VLBI网(The Chinese VLBI Network,CVN)联测。     

嵌入式千兆以太网传输系统在VLBI硬件相关处理机中的应用

甚长基线干涉测量（VLBI）是重要的射电天文技术，具有极高的空间分辨率，是国际上广泛采用的深空探测器高精度测量手段。硬件相关处理机则是VLBI数据预处理的核心设备。随着以FPGA（Field Programmable Gate Array）为实现平台的嵌入式系统的不断发展，用FPGA和嵌入式系统作为实现方式成为硬件相关处理机研究的一个方向。研究了如何利用嵌入式千兆以太网传输系统对硬件相关处理机的长期累加子系统（LTA）进行改进。     

Resolving the Degeneracy: Experimental Tests of the New Self Creation Cosmology and a Heterodox Prediction for Gravity Probe B

The new theory of Self Creation Cosmology has been shown to yield a concordant cosmological solution that does not require inflation, exotic non-baryonic Dark matter or unknown Dark Energy to fit observational constraints. In vacuo there is a conformal equivalence between this theory and canonical General Relativity and as a consequence an experimental degeneracy exists as the two theories predict identical results in the standard tests. However, there are three definitive experiments that are able to resolve this degeneracy and distinguish between the two theories. Here these standard tests and definitive experiments are described. One of the definitive predictions, that of the geodetic precession of a gyroscope, has just been measured on the Gravity Probe B satellite, which is at the present time of writing in the data processing stage. This is the first opportunity to falsify Self Creation Cosmology. The theory predicts a ‘frame-dragging’ result equal to GR but a geodetic precession of only 2/3 the GR value. When applied to the Gravity Probe B satellite, Self Creation Cosmology predicts an E–W gravitomagnetic/frame-dragging precession, equal to that of GR, of 40.9 milliarcsec/yr but a N–S gyroscope (geodetic + Thomas) precession of just 4.4096 arcsec/yr.     

乌鲁木齐天文站Mark 5系统实施及其研究

分析了VLBIMark5磁盘记录系统的硬件结构和软件结构。对其软件实现做了设计层面上的分析。给出了乌鲁木齐天文站Mark5系统实施后的操作流程图。分析了Haystack天文台e VLBI软件的结构。     

Apparent proper motions of radio sources from geodetic VLBI data

According to the most recent geodetic VLBI data, some of the radio sources that define the fundamental celestial reference frame are astrometrically unstable. In contrast to the stellar proper motions described by a linear function, the apparent proper motions of quasars are more complex. Therefore, they are difficult to approximate by a particular model. Being disregarded, the positional instability of the defining quasars can lead to a bias in the estimates of other parameters from observations, for example, the nutation angle corrections.     

Study of a Bistatic Radar System Using VLBI Technologies for Detecting Space Debris and the Experimental Verification of its Validity

Space debris are increasing around the Earth. The observation of space debris is a key issue for the investigation and monitoring of space environment. But the observation opportunities and the detection ability are limited in existing monostatic radar systems. This paper proposes a bistatic radar which is composed of a transmitting station and a receiving-only station. A carrier wave modulated by PN-PSK signals is used in combination with a VLBI (Very Long Baseline Interferometry) recorder for range measurement between space debris and stations. The receiving radio wave is processed on the basis of VLBI techniques. Accordingly, the system is shown to have significant advantages over a monostatic radar. We actually formed a bistatic radar system, and observed a satellite in order to experimentally verify the validity. The configuration of the system, data analysis and the experimental results are described.     

AO 0235＋164的喷流在旋转吗？

本文给出BLLac天体AO0235＋164在SGDz的多历元VLBI观测所得到的图象．在一定的假设条件下，根据VLBI观测结果可推算出该源的子源以税超光速速率向外扩展，最大的扩展速率为（27±6）C．从AO0235＋164喷流位置角的变化，我们推测该源的喷流可能在旋转和中央“引擎”有过动的可能性．进一步的多历元VLBI观测将被用来证实这种推断．为了得到更精细的射电结构，我们准备对AO0235＋164做空间VLBI观测．我们已做了相应的模拟试验．